Environmental Review of the Proposed Mattawoman Energy Center

Transcription

PSC Case No. 9330
PPRP Exhibit____(FSK-3)
Environmental Review of the
Proposed Mattawoman Energy
Center Project
DRAFT
July 10, 2015
TABLE OF CONTENTS
LIST OF ACRONYMS
VII
EXECUTIVE SUMMARY
1.0
2.0
3.0
1
INTRODUCTION
1-1
1.1
BACKGROUND
1-1
1.2
DOCUMENT ORGANIZATION
1-2
PROJECT DESCRIPTION
2-1
2.1
SITE DESCRIPTION
2-2
2.2
PROPOSED PROJECT COMPONENTS
2-3
2.3
LINEAR FACILITIES
2.3.1
Electrical Interconnection Facilities
2.3.2
Natural Gas Facilities
2.3.3
Water Supply/Wastewater
2-7
2-7
2-8
11
EXISTING SITE CONDITIONS
3-1
3.1
TOPOGRAPHY, SOILS, AND GEOLOGY
3.1.1
Topography
3.1.2
Soils
3.1.3
Regional Geology
3-1
3-1
3-1
3-1
3.2
WATER RESOURCES
3.2.1
Hydrogeologic Units
3.2.2
Groundwater Conditions
3.2.3
Groundwater Use in the Vicinity of the Mattawoman Site
3-4
3-4
3-4
3-10
3.3
SURFACE WATER RESOURCES
3-11
3.4
CLIMATOLOGY AND AIR QUALITY
3.4.1
Weather and Climate
3.4.2
Ambient Air Quality
3-12
3-12
3-12
3.5
BIOLOGICAL RESOURCES
3.5.1
Project Site
3.5.2
Linear Facilities and Substation
3-15
3-15
3-20
MD PPRP
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MATTAWOMAN ENERGY CENTER–CASE 9330-07/10/15
4.0
3.6
REGIONAL SOCIOECONOMIC SETTING
3.6.1
Population Trends
3.6.2
Employment and Income
3.6.3
Land Use and Zoning
3.6.4
Recreational, Scenic, and Cultural Sites
3.6.5
Public Services and Safety
3.6.6
Transportation
3-32
3-32
3-33
3-34
3-36
3-39
3-41
3.7
NOISE
3.7.1
3.7.2
3-43
3-43
3-45
Definition of Noise
Existing Noise Levels
AIR QUALITY IMPACTS
4-1
4.1
AIR QUALITY IMPACT ASSESSMENT BACKGROUND AND
METHODOLOGY
4.1.1
Overview
4.1.2
Regulatory Considerations
4-1
4-1
4-1
4.2
PROPOSED PROJECT SOURCE CHARACTERIZATION
4.2.1
Combustion Turbines
4.2.2
Ancillary Units
4-3
4-3
4-4
4.3
PROJECT AIR EMISSIONS
4.3.1
CTs/HRSGs and Duct Burners
4.3.2
Auxiliary Boiler
4.3.3
Fuel Gas Heater
4.3.4
Emergency Generator and Fire Water Pump
4.3.5
Cooling Tower
4.3.6
Circuit Breakers
4.3.7
Natural Gas Component Fugitive Emissions
4.3.8
Ammonia Emissions
4.3.9
HAP Emissions
4.3.10
Summary of Project Emissions
4.3.11
Construction Emissions
4-8
4-8
4-17
4-18
4-19
4-21
4-22
4-22
4-23
4-23
4-24
4-28
4.4
PREVENTION OF SIGNIFICANT DETERIORATION (PSD)
4.4.1
Applicability
4.4.2
Best Available Control Technology (BACT) Analyses
4.4.3
NAAQS and PSD Increment Compliance Demonstration
4-29
4-29
4-30
4-65
4.5
NONATTAINMENT NEW SOURCE REVIEW (NA-NSR)
4.5.1
LAER Evaluation
4.5.2
Offsets
4.5.3
Additional NA-NSR Requirements
MD PPRP
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4-90
4-91
4-103
4-104
4.6
5.0
6.0
REGULATORY APPLICABILITY ANALYSIS
4.6.1
Federal Regulatory Requirements
4.6.2
State Regulatory Requirements
4.6.3
Maryland Toxic Air Pollutants (TAPs) Analysis
ANALYSIS OF OTHER ENVIRONMENTAL IMPACTS
4-105
4-105
4-113
4-120
5-1
5.1
IMPACTS TO BIOLOGICAL RESOURCES
5.1.1
Overview
5.1.2
Project Site
5.1.3
5.1.4
General Recommendations
5-1
5-1
5-1
5-4
5-34
5.2
IMPACTS TO GROUND WATER
5.2.1
Construction Impacts
5.2.2
Dewatering for Linear Facilities
5.2.3
Routine or Accidental Releases to Groundwater
5.2.4
Recommendations
5-36
5-36
5-48
5-49
5-50
5.3
SOCIOECONOMIC IMPACTS
5.3.1
5.3.2
Population and Housing
5.3.3
Land Use
5.3.4
Transportation
5.3.5
Visual Quality
5.3.6
Fiscal
5-54
5-54
5-55
5-56
5-61
5-66
5-69
5.4
CULTURAL IMPACTS
5-71
5.5
NOISE IMPACTS
5.5.1
Summary of Regulatory Requirements
5.5.2
Estimate of Noise Impacts
5-73
5-74
5-74
5.6
ANALYSIS OF OTHER ENGINEERING IMPACTS
5.6.1
Water Supply
5.6.2
Fuels and Chemicals Delivery, Handling, and Storage
5.6.3
Solid and Hazardous Waste Handling and Disposal
5.6.4
Construction Activities Near the DRMO Superfund Site
5.6.5
Stormwater Management
5-77
5-77
5-87
5-89
5-89
5-92
CONCLUSIONS AND RECOMMENDATIONS
6-1
6.1
AIR QUALITY
6-1
6.2
WATER SUPPLY
6-2
MD PPRP
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7.0
6.3
6-3
6.4
6-10
6.5
NOISE IMPACTS
6-15
REFERENCES
7-1
LIST OF TABLES
Table 3-1
Table 3-2
Table 3-3
Table 3-4
Table 4-1
Table 4-2
Geologic Units Beneath the Mattawoman Site
Sensitive Resources in the Four Watersheds in Southern Maryland
Typical Sound Levels for Common Sources (dBA)
Average L90 Sound Levels at Mattawoman Site
Mattawoman Project Air Emission Sources
Maximum Short-Term Emission Rates for Normal Operation – For One
CT/HRSG
Projected Number of Annual Startup and Shut down Events
Projected Emissions During Startup and Shutdown Periods – For One
CT/HRSG
Maximum Annual Emissions from Two CT/HRSGs Combined
Projected HAP Short-Term Emissions from Normal Operation of One
CT/HRSG
Summary of Annual HAP Emissions – Two CT/HRSGs Combined
Potential Emissions from the Auxiliary Boiler
Potential Emissions from the Fuel Gas Heater
Potential Emissions from the Emergency Generator and the Fire Water Pump
Potential Emissions from the Cooling Tower
Potential Fugitive Emissions from Natural Gas Components
Total Potential HAP Emissions from All Proposed Project Sources
Summary of Short-Term Emissions from the Project
Summary of Annual Emissions from the Project (tpy)
Emissions Associated with Construction Activities
PSD Applicability Analysis for the Project
Proposed PM, PM10, and PM2.5 BACT Determinations
Proposed CO BACT Determinations
Proposed SAM BACT Determinations
Recent GHG Permit Determinations
Proposed GHG BACT Determinations
Micrometeorological Variables Comparison
Data Characteristics of KDCA Meteorological Data
KDCA Monthly Snowfall and Maximum Snow Depth (Inches)
Table 4-3
Table 4-4
Table 4-5
Table 4-6
Table 4-7
Table 4-8
Table 4-9
Table 4-10
Table 4-11
Table 4-12
Table 4-13
Table 4-14
Table 4-15
Table 4-16
Table 4-17
Table 4-18
Table 4-19
Table 4-20
Table 4-21
Table 4-22
Table 4-23
Table 4-24
Table 4-25
MD PPRP
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Table 4-26
Table 4-27
Table 4-28
Table 4-29
Table 4-30
Table 4-31
Table 4-32
Table 4-33
Table 4-34
Table 4-35
Table 4-36
Table 4-37
Table 4-38
Table 4-39
Table 4-40
Table 4-41
Table 4-42
Table 4-43
Table 4-44
Table 4-45
Table 4-46
Table 5-1
Table 5-2
Table 5-3
`
Table 5-4
Table 5-5
Table 5-6
Table 5-7
KDCA Monthly Surface Moisture Assignments
Stack Characteristics Defined by Mattawoman
Emissions Parameters for Mattawoman Sources Used in PPRP and MDEARMA’s Modeling Analysis
Background Monitor Concentrations
NACAA PM2.5 Ratio Calculation Methodology
Offsite NOX Facilities Modeled by PPRP and MDE-ARMA
Offsite PM2.5 Facilities Modeled by PPRP and MDE-ARMA
Offsite CO Facilities Modeled by PPRP and MDE-ARMA
Summary of Class II SIL Analysis Conducted by Mattawoman
Summary of Class II SIL Analysis Conducted by PPRP and MDE-ARMA
Summary of NAAQS Analysis Conducted by Mattawoman
Summary of Increment Analysis Conducted by Mattawoman
Summary of NAAQS Analysis Conducted by PPRP and MDE-ARMA
Summary of Increment Analysis Conducted by PPRP and MDE-ARMA
Summary of Class I Analysis Conducted by Mattawoman
NANSR Applicability Analysis for the Project
Proposed NOX LAER Limitations
Proposed VOC LAER Determinations
Emission Standards for the Emergency Engines (g/bhp-hr)
TAP Screening Thresholds and Allowable Emission Rates
Cooling Tower Worst-Case Ammonia and Phosphorus Emission Rates
Cumulative Constraint Map Scale
Dewatering Calculation
Distance-Drawdown Calculations for One Year at the Annual Average
Withdrawal Rate and Month of Maximum Use Rate (Specific Yield = 0.2)
Distance-Drawdown Calculations for One Year at the Annual Average
Withdrawal Rate and Month of Maximum Use Rate (Specific Yield = 0.1)
Maximum Allowable Noise Levels (dBA) for Receiving Land Use Categories
Predicted Sound Pressure Levels (dBA)
Water Quality Parameters in Piscataway WWTP Effluent
LIST OF FIGURES
Figure 1-1
Figure 2-1
Figure 2-2
Figure 2-3
Figure 2-4
Figure 2-5
Figure 3-1
Figure 3-2
Figure 3-3
Figure 3-4
Mattawoman Energy Center Site Location
Topographical Map of Site Location
Mattawoman Site Layout
Proposed Mattawoman Substation
Natural Gas Pipeline Route
Reclaimed Water Pipeline
Geologic Cross-Sections A-A’ and B-B’
Conceptual Groundwater Contours for the Brandywine Formation
Watershed Boundaries on the Brandywine DRMO Site
Groundwater Users in the Vicinity of the Mattawoman Site
MD PPRP
v
Figure 3-5
Land Use and Limits of Disturbance on the Mattawoman Energy Center
Project Site
Watersheds in Vicinity of Proposed Site
Proposed Substation Site located on Cherry Tree Crossing Road, adjacent
to the PEPCO 230-kV transmission line corridor
Noise Monitoring Locations
Recommended Approach to Estimating Emissions
5-year Wind Rose (2009-2013): Reagan National Airport (KDCA)
Speciation of Annual PM2.5 Concentration – 2012 PM2.5 Design Value
– Prince George’s Equestrian Center Monitor
Limits of Disturbance for Site Plan
Proposed Reclaimed Water and Natural Gas Pipeline Route and the
Eleven Environmentally Sensitive Areas
Green Infrastructure and FIDS Habitat along the Proposed Mattawoman
Reclaimed Water and Natural Gas Pipeline Corridors and the Generator
Lead Line Right-Of-Way
Cumulative Environmental Constraints Map
Mattawoman Creek Area Showing the Location of the Proposed Natural
Gas Pipeline Route
Map of Environmentally Sensitive Areas of Jordan Swamp
Watershed Boundary for the Unnamed Tributary
Existing and Proposed Monitoring Well Locations on the Mattawoman
and Brandywine DRMO Sites
Height, Accident Potential, and Noise Intensity Zones South of Joint
Base Andrews
Andrews Tri-Link Facilities
Noise Receptor Locations
Water Balance – Summer Maximum
Water Balance – Winter Maximum
Proposed Lift Station at Piscataway WWTP
Transmission Pole Foundations Proposed for DRMO Site
Figure 3-6
Figure 3-7
Figure 3-8
Figure 4-1
Figure 4-2
Figure 4-3
Figure 4-4
Figure 5-1
Figure 5-2
Figure 5-3
Figure 5-4
Figure 5-5
Figure 5-6
Figure 5-7
Figure 5-8
Figure 5-9
Figure 5-10
Figure 5-11
Figure 5-12
Figure 5-13
Figure 5-14
Figure 5-15
LIST OF APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Initial Recommended Licensing Conditions
Detailed Air Emission Calculations
Summary of EPA’s RBLC Database and Recent Permit Determinations
Responses to Data Requests
Surficial Aquifer Hydraulic Conductivity and Distance-Drawdown
Calculations
Evaluation of Potential Impacts to the Remediation of the Brandywine
DRMO Superfund Site
Appendix F
MD PPRP
vi
LIST OF ACRONYMS
AASHTO
American Association of State Highway
Transportation Officials
AB
Auxiliary Boiler
AER
Allowable Emission Rate
AERMOD
EPA air model used in analysis
AGL
Above Ground Level
ALS
Advanced Life Support
ANSI
American National Standards Institute
APE
Area of Potential Effect
AQRS
Air Quality Related Values
AQS
Air Quality System
ARM
Ambient Ratio Method
ASME
American Society of Mechanical Engineers
ASOS
Automated Surface Observation System
AST
Aboveground storage tank
ATHA
Anacostia Trails Heritage Area
AVO
Audio/visual/olfactory
BACT
Best available control technology
BGS
Below ground surface
BIONET
Biodiversity Conservation Network
BMP
Best Management Practice
BOD
Biological Oxygen Demand
BPIP
Building Input Profile Program
CAA
Clean Air Act
CAIR
Clean Air Interstate Rule
CAM
Compliance Assurance Monitoring
CB
Circuit Breaker
CBCA
Chesapeake Bay Critical Area
CCCT
Combined Cycle Combustion Turbine
CCS
Carbon Capture and Sequestration
CEMS
Continuous Emissions Monitoring System
MD PPRP
vii
CFC
Chlorofluorocarbons
CFR
Code of Federal Regulations
CH4
Methane
CHA
Certified Heritage Areas
CHP
Combined Heat and Power
CI
Compression Ignition
CO
Carbon monoxide
CO2
Carbon dioxide
CO2e
Carbon dioxide equivalent
COMAR
Code of Maryland Regulations
CPCN
Certificate of Public Convenience and Necessity
Cr
Chromium
CSAPR
Cross State Air Pollution Rule
CSXT
CSX Transportation, Inc.
CT
Combustion Turbine
CTBR
Cooling tower blowdown and recovery
CTG
Combustion Turbine Generator
CTP
Consolidated Transportation Program
CWP
Circulating Water Pipe
DB
Duct Burner
DER
Prince George’s County Department of
Environmental Resources
DLLR
Maryland Department of Labor, Licensing, and
Regulations
DLN
Dry low-NOx
DNR
Maryland Department of Natural Resources
DOD
U.S. Department of Defense
DOT
Maryland Department of Transportation
DPW&T
Prince George’s County Department of Public Works
and Transportation
DPZ
Prince George’s County Department of Planning and
Zoning
DRMO
Defense Reutilization and Marketing Office
MD PPRP
viii
ECT
Environmental Consulting & Technology, Inc.
EDI
Electrodeionization
EGU
Electric Generating Unit
EMS
Emergency Medical Service
ENR
Enhanced nutrient removal
EPA
U.S. Environmental Protection Agency
ERC
Emission Reduction Credit
ERD
Environmental Review Document
ERM
Environmental Resources Management, Inc.
ESP
Electrostatic precipitators
FAA
Federal Aviation Administration
FCA
Forest Conservation Act
FEMA
Federal Emergency Management Agency
FGD
Flue Gas Desulfurization
FGR
Flue Gas Recirculation
FIDS
Forest interior-dwelling species
FLM
Federal Land Managers
FR
Fuel reburning
FY
Fiscal Year
GEP
Good Engineering Practice
GHG
Greenhouse gas
GI
General industrial
GI
Green Infrastructure
GIS
Geographic Information System
GSU
Generator Step Up
GWP
Global Warming Potential
HAP
Hazardous air pollutant
HDD
Horizontal Directional Drilling
HFC
Hydrofluorocarbons
HHV
Higher Heating Value
HRSG
Heat Recovery Steam Generator
ICE
Internal Combustion Engine
MD PPRP
ix
ILUC
Interim Land Use Code
ISO
International Organization for Standardization
JBA
Joint Base Andrews, United States Air Force
JEDI
Jobs and Economic Development Impacts
JLUS
Joint Land Use Study
KDCA
Reagan National Airport
LAER
Lowest achievable emission rate
LDAR
Leak Detection and Repair Program
LNB
Low NOx Burner
LOS
Level of service
MAA
Maryland Aviation Administration
MACT
Maximum Achievable Control Technology
MALPF
Maryland Agricultural Land Preservation Foundation
MDE
Maryland Department of the Environment
MDE-ARMA
Maryland Department of the Environment Air and
Radiation Management Administration
MDE-WMA
Maryland Department of the Environment Water
Management Administration
MDOT
Maryland Department of Transportation
MGS
Maryland Geological Survey
MHT
Maryland Historical Trust
MHAA
Maryland Heritage Areas Authority
MIHP
Maryland Inventory of Historic Properties
MIOZ
Military Installation Overlay Zone
MNCPPC
Maryland National Capital Park and Planning
Commission
MOA
Memorandum of Agreement
MOT
Maintenance of Traffic
N2O
Nitrous oxide
NAAQS
National Ambient Air Quality Standard
NACAA
National Association of Clean Air Agencies
NAMS
National Air Monitoring Stations
NA-NSR
Non-Attainment New Source Review
MD PPRP
x
NCDC
National Climate Data Center
NCore
National Core
NED
National Elevation Dataset
NEPA
National Environmental Policy Act
NERC
North American Electric Reliability Corporation
NESHAP
National Emissions Standards for Hazardous Air
Pollutants
NG
Natural gas
NHP
Natural Heritage Program
NMHC
Non-methane hydrocarbons
NOAA
National Oceanic and Atmospheric Association
NO2
Nitrogen dioxide
NOx
Nitrogen oxides
NPDES
National Pollutant Discharge Elimination System
NPL
National Priorities List
NPS
Nominal Pipe Size
NSPS
New Source Performance Standard
NTWSSC
Nontidal Wetlands of Special State Concern
NWA
National Wildlife Area
NWR
National Wildlife Refuge
NWS
National Weather Service
O3
Ozone
OAQPS
Office of Air Quality Planning and Standards
OEM
Office of Emergency Management
O&M
Operations & Maintenance
OSHA
Occupational Safety and Health Administration
PAMS
Photochemical air monitoring stations
Pb
Lead
PCBs
polychlorinated biphenyls
PEPCO
Potomac Electric Power Company
PFA
Priority Funding Area
PFC
Perfluorocarbons
PGCPD
Prince George’s County Planning Department
MD PPRP
xi
PGCPS
Prince George’s County Public Schools
PJM
PJM Interconnection, LLC
PM/PM10
Particulate matter; 10 microns in diameter
PM2.5
Particulate matter; 2.5 microns in diameter (Fines)
PPRP
Power Plant Research Program
PRC
Patuxent River Commission
PSC
Maryland Public Service Commission
PSD
Prevention of Significant Deterioration
RACT
Reasonably Available Control Technology
RBLC
U.S. EPA RACT/BACT/LAER Clearinghouse
RC
Rural Conservation
RICE
Reciprocating Internal Combustion Engine
RMP
Risk Management Practice/Plan
ROW
Right-of-way
RTE
Rare, Threatened, and Endangered Species
SAM
Sulfuric acid mist
SCR
Selective catalytic reduction
SER
Significant Emission Rate
SF6
Sulfur hexafluoride
SGCN
Species of Greatest Conservation Need
SHA
State Highway Administration
SIL
Significant Impact Levels
SIP
State Implementation Plan
SLAMS
State and local air monitoring stations
SMC
Significant Monitoring Concentrations
SMECO
Southern Maryland Electric Cooperative
SMHA
Southern Maryland Heritage Area
SNCR
Selective Non-Catalytic Reduction
SOP
Standard operating procedures
SO2
Sulfur dioxide
SO3
Sulfur trioxide
SPCC
Spill Prevention, Control, and Countermeasure
MD PPRP
xii
SSPRA
Sensitive Species Project Review Area
STG
Steam Turbine Generator
SUSD
Startup/shutdown
SVOC
Semi-volatile organic compounds
SWM
Stormwater management
SWPPP
Stormwater Pollution and Prevention Plan
TAP
Toxic air pollutant
TCL
U.S. EPA Target Compound List
TDS
Total dissolved solids
TIS
Traffic Impact Study
TSP
Total suspended particulates
ULSD
Ultra low-sulfur diesel
USACE
U.S. Army Corps of Engineers
USAF
U.S. Air Force
USGS
U.S. Geological Survey
USFWS
U.S. Fish and Wildlife Service
VHB
Vanasse Hangen Brustlin
VOC
Volatile organic compounds
WHS
Maryland Wildlife and Heritage Service
WIA
Prince George’s County Workforce Information
Authority
WMA
MDE Wastewater Management Administration
WPRP
Prince George’s County Watershed Protection and
Restoration Program
WRAS
Watershed Restoration Action Strategy
WSSC
Washington Suburban Sanitary Commission
WSSC
Wetlands of Special State Concern
WWTP
Wastewater treatment plant
ZLD
Zero liquid discharge
MD PPRP
xiii
UNITS
Btu/ft3
British thermal units per cubic foot
°F
degrees Fahrenheit
dB
decibel
dBA
A-weighted decibels
ft
feet
ft/d
feet per day
ft-msl
feet above mean sea level
FTU
formazin turbidity units
gpd
gallons per day
gpm
gallons per minute
gpy
gallons per year
g/hp-hr
grams per horsepower hour
g/kW-hr
grams per kilowatt hour
gr S/100 scf
grains sulfur per 100 standard cubic feet
hp
horsepower
hr
hour
km
kilometer
kPa
kilopascal
kV
kilovolt
kW
kilowatt
lb
pound
lb/MWh
pounds per megawatt hour
Leq
equivalent sound pressure level
L90
sound pressure level that is exceeded 90% of the time
m
meter
mgd
million gallons per day
mg/L
milligrams per liter
MMBTU
millions of British thermal units
MW
megawatt
NTU
nephelometric turbidity units
ppm
parts per million
MD PPRP
xiv
ppmv
parts per million by volume
ppmvd
parts per million by volume on a dry basis
scf
standard cubic foot
tpy
tons per year
yr
year
MD PPRP
xv
EXECUTIVE SUMMARY
On July 19, 2013, Mattawoman Energy, LLC (Mattawoman) submitted an
application to the Maryland Public Service Commission (PSC) for a
Certificate of Public Convenience and Necessity (CPCN) that would
authorize the construction and operation of the Mattawoman Energy
Center Project (Project). This Project is identified as PSC Case No. 9330.
The proposed Project will consist of a new nominal 990-megawatt (MW),
two-on-one, combined-cycle electric generating facility configured with
two combustion turbines (CTs), two heat recovery steam generators
(HRSGs) with supplemental duct firing, and one steam turbine generator
(STG) in a multi-shaft arrangement to be located in southern Prince
George’s County, Maryland. The proposed Project will be constructed
and operated on an 88-acre parcel located near Brandywine, Maryland.
Each combustion turbine generator (CTG) has the potential to generate up
to 286 MW of electric energy. The CTG exhaust gases will be used to
generate steam in the HRSGs, which will use reheat design with duct
firing. Steam from the HRSGs will be admitted to a reheat, multi-shell,
condensing STG capable of generating 436 MW of electric energy. The
total gross capacity of the plant will be 1,008 MW; subtracting 18 MW for
auxiliary load yields the nominal rating of 990 MW. The proposed Project
will also use a wet-cooled condenser for steam turbine generator cooling.
The HRSG will include a selective catalytic reduction (SCR) system and an
oxidation catalyst system. The Project will use a multi-cell wet cooling
tower for heat rejection. Project construction will include site
development, the generating unit, and the balance of plant.
The proposed CTGs will be fired by natural gas transported via a new
pipeline that will interconnect with the Dominion Transmission, Inc. Cove
Point gas transmission line located approximately 7 miles south of the
Project Site. Cooling water for the Project will consist of reclaimed
wastewater from the Piscataway Wastewater Treatment Plant (WWTP)
located approximately 9 miles west of the Project Site. The Project will use
a zero liquid discharge (ZLD) system; there will be no discharge of
industrial wastewater to surface or groundwater.
The proposed Project will deliver electricity to the grid via interconnection
with a new 230-kilovolt (kV) transmission line designed and built by
Mattawoman. Mattawoman will own the portion of the transmission line
to the point of interconnection on the existing PEPCO 230-kV transmission
line located approximately 2.3 miles north of the proposed Project where a
new substation will be built. PEPCO will design and construct the new
MD PPRP
ES-1
230-kV substation/switchyard and Mattawoman will design, build, and
own a disconnected switch, breaker and associated facilities within the
PEPCO substation/switchyard. Mattawoman will be responsible for
property acquisition for the new substation.
The Department of Natural Resources (DNR) Power Plant Research
Program (PPRP), coordinating with other State agencies, performed this
environmental review of the Project as part of the licensing process
administered by the Maryland PSC. Before the proposed Project can be
constructed, Mattawoman must obtain a CPCN from the PSC. PPRP’s
review was conducted to evaluate the potential impacts to environmental
and cultural resources for the proposed facility, pursuant to Section 3-304
of the Natural Resources Article of the Annotated Code of Maryland. The
review of the proposed Project was based on information filed by the
company in its original CPCN application, supplemental filings,
supplemental direct testimony, and responses to PPRP Data Requests
Nos. 1 through 17.
PPRP used the analysis of potential impacts as the basis for establishing
recommended licensing conditions for operating the proposed facility,
pursuant to Section 3-306 of the Natural Resources Article. The initial
recommended licensing conditions are included as Appendix A. PPRP’s
recommendations are made in concert with other units within DNR, as
well as the Maryland Departments of Environment, Agriculture, Business
and Economic Development, Planning, and Transportation, and the
Maryland Energy Administration.
MD PPRP
ES-2
1.0
INTRODUCTION
1.1
BACKGROUND
On July 19, 2013, Mattawoman Energy, LLC (Mattawoman) filed for an
Application for a Certificate of Public Convenience and Necessity (CPCN)
to construct a nominally rated 859 megawatt (MW) combined-cycle
combustion turbine/heat recovery steam generator electric generating
facility. Since then, plans for the Project have undergone several updates,
and it is being proposed as a nominally rated 990-MW plant. The Project
will be located at 14175 Brandywine Road, Brandywine, Prince George’s
County, Maryland, on an 88-acre site owned by Mattawoman (see Figure
1-1). The Project will consist of an 990-MW, two-on-one, combined-cycle
electric generating facility configured with two combustion turbines
(CTs), two heat recovery steam generators (HRSGs) with supplemental
duct firing, and one steam turbine generator (STG) in a multi-shaft
arrangement.
On June 30, 2014, Mattawoman filed supplemental direct testimony and
substitute Environmental Review Document (ERD) Appendix A-1 to
support its original CPCN application with the Public Service
Commission (PSC). The supplemental filing was intended to clarify issues
associated with the proposed routing for the linear facilities, and
contained updated information and environmental analyses pertaining to
the electrical interconnection, natural gas pipeline, and reclaimed water
pipeline.
Mattawoman filed further supplemental testimony and a Supplemental
Environmental Review Document in January 2015 to include the generator
lead line as part of the CPCN review. This January 2015 Supplemental
Filing also reflected changes in the combustion turbine make and model,
and thus changes to projected environmental impacts of the Project.
Mattawoman filed an additional substation Supplemental Filing in April
2015 to address impacts of the new substation construction for the
generator lead line. Figure 1-1 shows the regional and site specific
location of the Mattawoman site.
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Figure 1-1
Mattawoman Energy Center Site Location
Source: Mattawoman CPCN 2013
1.2
DOCUMENT ORGANIZATION
This report synthesizes the evaluations that PPRP has conducted to
evaluate potential impacts to environmental and cultural resources from
the Project. The information is organized into the following sections:
•
MD PPRP
Section 2 provides a description of the proposed Project;
1-2
•
Section 3 describes the existing environmental and socioeconomic
conditions at the Site and in the vicinity;
•
Section 4 describes the air impacts associated with the proposed
Project and the relevant regulatory requirements;
•
Section 5 addresses other impacts, including terrestrial, ground
water from construction and operation, socioeconomic, and noise;
•
Section 6 summarizes the findings of PPRP’s evaluations.
Six appendices are also included in the report, as follows:
•
Appendix A provides reference to the State’s Letter of
Recommendation and the recommended licensing conditions for
the proposed Mattawoman Energy Center Project;
•
Appendix B contains the detailed air emissions calculations;
•
Appendix C provides a summary of the EPA’s RBLC database and
recent permit determinations;
•
Appendix D provides Mattawoman’s responses to data requests
that are specifically referenced in this document;
•
Appendix E provides PPRP’s surficial aquifer hydraulic
conductivity and distance drawdown calculations to support the
construction dewatering evaluation; and
•
Appendix F provides PPRP’s evaluation of potential impacts to the
remediation of the Brandywine DRMO Superfund Site.
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2.0
PROJECT DESCRIPTION
Mattawoman proposes to develop a new nominally rated 990-MW, twoon-one combined cycle, natural gas-fired, electric generating facility. The
generating units will include two HRSGs with supplemental duct firing,
and one STG in a multishaft arrangement. The Project will include an
SCR system and an oxidation catalyst system for air pollution control. A
multi-celled wet cooling tower will be used for heat rejection. The Project
equipment will be entirely outdoors, with manufacturer-supplied
enclosures provided for the CTs, STG, and HRSG. The CTs will be
Siemens SGT6-8000H machines, each capable of producing a nominal 286MW of electricity, and a Siemens SST-5000ST steam turbine with a
nameplate rating of 436 MW. The combustion turbine net heat rate in
combined cycle mode at base load International Organization for
Standardization (ISO) conditions with duct burner firing is 6,793
Btu/kWh. The CTs will run solely on natural gas and will be capable of
operating at 50% to 100% load. For this Project, the CTs will operate at
75% to 90% capacity. There will be two emergency oil-fired diesel
engines, one for fire protection that will include an emergency firewater
pump and the other for emergency power during loss of electrical power.
The Project will also include a heat input auxiliary boiler, fuel gas heater,
and the associated ancillary equipment necessary for the generation of
electricity.
The Project and associated facilities will encompass approximately 28
acres of the 88-acre Site with limits of disturbance of 38.8 acres.
Mattawoman will design, build, own, and permit an electric generator
lead line as a part of this Project for interconnection to the electricity grid.
The generator lead line will interconnect at a point on the existing
Potomac Electric Power Company (PEPCO) 230-kV transmission line
located 2.3 miles north of the Site. PEPCO will construct and own a new
substation/switchyard at the point of interconnection; Mattawoman will
design, build, and own a disconnected switch, breaker and associated
facilities within the PEPCO substation/switchyard.
The Project will require water for cooling tower makeup, HRSG makeup,
evaporative cooler makeup, NOx emissions control, periodic equipment
washes, and sanitary uses, with cooling tower makeup being the largest
use. The water supply for the Project will be obtained from reclaimed
wastewater effluent from the nearby Piscataway WWTP. A 10-mile long
pipeline will carry reclaimed water from Piscataway to the proposed
Project.
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2-1
2.1
SITE DESCRIPTION
The Project will be located at 14175 Brandywine Road, Brandywine, Prince
George’s County, Maryland, on an 88-acre Site owned by Mattawoman.
The Site will be located approximately 12.1 miles southeast of
Washington, D.C., 6 miles northeast of Waldorf, MD, and 0.3 miles east of
Brandywine, MD. The Project with associated facilities will develop a 28acre area. The Project Site is bordered on the north by Brandywine Road
and on the south by a heavily forested 1,635‒acre tract of land owned by
the United States Government, United States Air Force (USAF) which
houses the Brandywine Radio Receiver (Globecom). The CSX
Transportation, Inc. (CSXT) rail line is located on the eastern boundary of
the Project Site and an automotive salvage yard is located to the west. The
Project Site is located in an industrially zoned district within the
Developing Tier land use designation. The surrounding land uses are
heavy industrial, military, public institutional, commercial, undeveloped,
and limited residential.
The USAF property located just to the north of Brandywine Road is the
Brandywine Defense Reutilization and Marketing Office (DRMO)
Superfund site, previously a U.S. Department of Defense (DOD) storage
area for electrical equipment and hazardous waste. The U.S.
Environmental Protection Agency (EPA) placed the Brandywine DRMO
site on the National Priorities List (NPL) in 1999.
Figure 2-1 shows the Site boundaries superimposed on a U.S. Geological
Survey (USGS) topographical map (Brandywine, Maryland quadrangle).
The elevation is approximately 235 feet above mean sea level (ft-msl). The
entire Site is at elevations above the 100-year floodplain, according to the
floodplain information from the Federal Emergency Management Agency
(FEMA 1985). Terrain elevations in the immediate area reach a maximum
of approximately 260 ft-msl. The topography of the 88-acre Project Site is
generally flat.
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2-2
Figure 2-1
Topographical Map of Site Location
Source: Mattawoman CPCN 2013
2.2
PROPOSED PROJECT COMPONENTS
Figure 2-2 shows the proposed Site layout. The Project will contain the
following components:
• Two Siemens SGT6-8000H CTs, 286-MW each
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•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
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Two HRSGs with supplemental duct firing and constant-speed
motor-driven feed water pumps
One Siemens SST-5000 ST 436-MW steam turbine generator (STG)
One 42-million-British-thermal-units-per-hour (MMBtu/hr) (higher
heating value [HHV]) heat input auxiliary boiler
One 230-kilovolt (kV) switchyard; two main step-up transformers
for the CTs and one for the steam turbine generator
Two 100-foot (ft)-tall stacks
One 12-cell mechanical cooling tower
A condensate system with two constant-speed motor-driven
pumps
One natural gas fuel system with filters, pressure control, metering,
and heating (if required) system
One service water treatment system consisting of multimedia filter
and reverse osmosis/mixed bed demineralization system with
portable trailers; two service water pumps; one raw/service/fire
water aboveground storage tank (AST); and one demineralized
water AST
A potable water system with an interface to the municipal public
water supply
An instrument and service air system
A closed cooling water system for cooling auxiliary equipment,
including two closed cooling water pumps, two closed cooling
water plate-type heat exchangers, and one expansion tank
One boiler feed water chemical injection system
One sanitary waste collection system to an existing sewage line
located near the Project Site boundary
A zero liquid discharge wastewater treatment system
A stormwater drainage system including an existing, 10-acre
stormwater pond and associated oil/water separator
Two selective catalytic reduction (SCR) systems for nitrogen oxides
(NOx) emissions control, including one 19% solution aqueous
ammonia system and associated AST
One ultra low-sulfur diesel (ULSD) fuel oil AST
Two thermal oxidation reaction systems for carbon monoxide (CO)
and volatile organic compounds (VOC) emissions control
One 13.8-MMBtu/hr (HHV) fuel gas heater
2-4
•
•
•
•
•
•
•
•
MD PPRP
One 1,490-horsepower (hp) diesel fuel-fired emergency generator
engine
A fire protection system, including one 305-hp diesel fuel-fired
emergency firewater pump engine and associated pump, one
motor-driven pump, and one jockey pump
Building structures, including an
administration/control/warehouse building, water treatment
building, main electrical/switchgear building with battery room,
and electrical switchgear and continuous emissions monitoring
system (CEMS) modules
A perimeter fence, lighting, gate, and guardhouse
A facility loop, interior roads, and personnel/visitor parking.
An electric interconnection to Potomac Electric Power Company’s
(PEPCO’s) existing transmission line
An electric interconnection (including lead line and substation) to
Potomac Electric Power Company’s (PEPCO’s) existing
transmission line
An interconnection to the existing Washington Suburban Sanitary
Commission’s (WSSC’s) Piscataway WWTP for the supply of
reclaimed water effluent as cooling water supply to the Project
2-5
Figure 2-2
Source: Mattawoman Supplemental Testimony, Exhibit ST-7, January 2015
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2.3
LINEAR FACILITIES
The Project will require a new electrical interconnection, a new reclaimed
water supply pipeline, and a new natural gas pipeline. Potable water
supply will be obtained from the existing water pipeline that services the
town of Brandywine.
2.3.1
Electrical Interconnection Facilities
The Project will be interconnected to the PEPCO electric transmission
network at the point of interconnection on the 230-kV existing PEPCO
Burches Hill to Talbert transmission line about 2.3 miles north of the
Project. Mattawoman will construct and own the generator lead line to
the point of interconnection. The proposed route for the generator lead
line moves in a northwesterly direction adjacent to the right-of-way
(ROW) for Brandywine Road. The route makes a couple of turns and
proceeds northeast along the CSXT railroad right-of-way, within the 69kV Southern Maryland Electrical Cooperative (SMECO) corridor, until it
reaches the PEPCO 230-kV transmission line. This segment of the route
also crosses an existing PEPCO 500-kV line, which traverses the route in
an east/west direction. Mattawoman is in the process of negotiating an
agreement with SMECO under which SMECO will relocate the 69-kV subtransmission line 39 ft east of its current location within the SMECO
easement.
PEPCO will construct and own the new substation/switchyard at the
point of interconnection. To avoid an agricultural preservation easement
that does not allow for the construction of a substation/switchyard, the
proposed location of the structure will be located on the southwest corner
of the intersection of the existing PEPCO 230-kV easement with Cherry
Tree Crossing Road. Within the PEPCO substation/switchyard,
Mattawoman will design, build, and own a disconnected switch, breaker
and associated facilities for interconnection with the proposed Project.
Mattawoman has included this new transmission line in the CPCN
application, and the environmental impacts associated with the
transmission line are within the scope of this review. Mattawoman
submitted a Substation Supplemental Environmental Review Document
in April 2015. Figure 2-3 shows the proposed layout of the new
substation.
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2-7
Figure 2-3
Proposed Mattawoman Substation
Source: Mattawoman Substation Supplemental ERD 2015
2.3.2
Natural Gas Facilities
Natural gas supply for the Project will be provided by a gas connection to
the existing Dominion Cove Point pipeline via a new radial line to the
Project to be constructed by Mattawoman.
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2-8
The proposed natural gas pipeline route is approximately 7.4 miles long
and will connect to an existing 36-inch interstate gas transmission line
south of the Mattawoman Site. From the Site, the proposed gas pipeline
route exits the eastern boundary of the Site, crosses the CSX
Transportation, Inc. (CSXT), railroad track, turns southeast, and follows
along the east side of the railroad track within a SMECO easement for
approximately 1.2 miles, at which point it turns southwest and crosses
back over the railroad track. From there, the gas route continues parallel
to the railroad track toward the southeast, but it is located on private
property approximately 250 feet south of the track. The proposed pipeline
route then extends approximately 0.25 mile to the intersection with a
PEPCO transmission line corridor. From there, the gas pipeline route
turns south/southwest and follows the west side of the electric
transmission line right-of-way for approximately 5 miles. At that point,
the route turns southeast, leaves an existing corridor, and travels a
greenfield route for approximately 0.9 mile to its intersection with the
existing 36-inch natural gas transmission line, which is located in Charles
County, Maryland. Overall, 85% of the route is located adjacent to an
existing linear corridor. The 0.9-mile greenfield route was chosen to avoid
crossing Jordan Swamp, a Wetland of Special State Concern (WSSC).
Figure 2-4 shows the proposed natural gas pipeline route.
MD PPRP
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Figure 2-4
Natural Gas Pipeline Route
Source: Mattawoman Supplemental CPCN Filing 2014.
MD PPRP
2-10
2.3.3
Water Supply/Wastewater
With the exception of potable water, the water supply for the Project will
be obtained from reclaimed wastewater effluent from the Piscataway
Wastewater Treatment Plant (WWTP). This will necessitate construction
of a new approximately 10.2-mile-long reclaimed water supply line from
the Piscataway WWTP to the Mattawoman Site. The proposed alignment
from the Site follows west along Brandywine Road for approximately 2
miles to Accokeek Road. From there, it follows Accokeek Road
approximately 6 miles to Berry Road. It turns northwest and follows
Berry Road approximately 2 miles to County Road 210, where it turns
south and runs approximately 0.2 mile to the Piscataway WWTP. The
intent is to construct the pipeline within the existing rights-of-way,
assuming there is sufficient room. Figure 2-5 shows the reclaimed water
pipeline route.
Only the reclaimed water supply pipeline will be constructed along this
route; there will be no return pipeline from the Site to the Piscataway
WWTP. Sanitary wastewater from the Project will be discharged via a
new pipeline interconnection to WSSC’s existing sewer system (the
Western Branch WWTP serves the Project site area). Only sanitary wastes
will be discharged via the new pipeline interconnection to WSSC. The
Project’s zero liquid discharge (ZLD) system avoids the need for larger
quantities of wastewater discharge. Periodic wastewater discharges
associated with turbine washes will be collected in an onsite tank and
disposed off site via truck transport.
MD PPRP
2-11
MATTAWOMAN ENERGY CENTER–CASE 9330- 7/10/15
Figure 2-5
Reclaimed Water Pipeline Route
Source: Mattawoman Supplemental CPCN Filing 2014
MD PPRP
2-12
3.0
EXISTING SITE CONDITIONS
3.1
TOPOGRAPHY, SOILS, AND GEOLOGY
3.1.1
Topography
The proposed Mattawoman Site is located approximately 235 feet above
mean sea level (ft-msl) (USGS 2011) in Prince George’s County, Maryland.
The Site topography is generally flat. Terrain elevations in the immediate
area reach a maximum of approximately 260 ft-msl. The majority of the
Site was prepared for site development by the previous land owner who
planned to develop the Site into a recycling center and business park. The
previous land owner had the Site cleared and graded, constructed a
stormwater management pond, and developed several access roads across
the property. The Site currently exists as open land.
3.1.2
Soils
The Site is located within the Coastal Plain region that typically consists of
sandy and loamy-textured soils. The soils in the proposed area for
development (southeastern portion of the Site) are classified as Aquasco
silt loam (ApA, zero to two percent slopes) and Lenni and Quindocqua
soils (LQA, zero to two percent slopes) (NRCS 2009). The Aquasco silt
loam is a fine to medium grain silty loam ranging in color from dark gray
to light brown, is poorly drained, and can be sticky when wet. The Lenni
and Quindocqua soils are found atop intrastream divides, are dark gray
loams, and are poorly drained.
3.1.3
Regional Geology
The Mattawoman Site is located within the Western Shore Uplands
Region in the Atlantic Coastal Plain Physiographic Province of Maryland.
The Coastal Plain consists of sediments that are unconsolidated and
interbedded sands, silts, and clays forming a wedge that thickens
eastward (Wilson 1986). The Coastal Plain sediments are approximately
2,000 feet thick beneath the Site and are underlain by pre-Cretaceous
consolidated sedimentary or metamorphic basement rock. These
sediments are composed of generally unconsolidated gravel, sand, silt,
and clay of the Cretaceous, Tertiary, and recent ages that were deposited
in fluvio-deltaic or marine environments. Table 3-1 summarizes the
geology and hydrogeology in the Site vicinity.
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3-1
The shallow (0-30 feet) surficial sediments consist of undifferentiated
Quaternary-age deposits. The Calvert, Nanjemoy, Marlboro, and Aquia
formations underlie the surficial sediments. Beneath these formations are
unconsolidated sediments of the Monmouth, Matawan, Magothy,
Patapsco, Arundel and Patuxent formations, which are underlain by
crystalline basement rock.
The Upland Deposits outcrop at the Mattawoman Site. The Upland
Deposits are known locally as the Brandywine Formation. The Upland
Deposits and Brandywine Formation nomenclature are used
interchangeably herein. The Upland Deposits are fluvial sediments
deposited in late Miocene and Pliocene Epochs presumably by the
ancestral Potomac River (Cleaves, et al. 1968; Glaser 2003). The deposits
mainly consists of poorly sorted medium to coarse sand (predominately
quartz) and medium to coarse gravel (predominantly quartzite, sandstone
and chert). The deposits are pale-gray, tan or buff in color and weather to
a yellow, orange, or shades of brown. The thickness of the formation
ranges from 0 to 50 feet (Cleaves, et al. 1968). Table 3-1 describes the the
geology of the units beneath the Mattawoman site.
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3-2
Table 3-1
Geologic Units Beneath the Mattawoman Site
Approximate
System
Quaternary
Series
Thickness (ft)
Hydrology
Lithology
25
Confining bed to poor
aquifer.
Sand, gravel, silt,
and clay. Surficial
unit.
Calvert and
Nanjemoy
Formations
250
Confining bed with
some sand lenses.
Domestic well use.
Silt, fine sand, and
clay.
Marlboro Clay
30
Confining bed.
Clay.
Holocene and
Pleistocene
Miocene and
Eocene
Tertiary
Unit
Paleocene
Aquia Formation
160
Major regional aquifer.
Glauconitic sand,
separated in places
by thin layers of silt
and clay.
Brightseat, Severn,
Monmouth and
Matawan
Formations
100
Confining bed.
Silt and clay, with
thin layers of sand.
Upper Cretaceous Magothy Formation
Cretaceous
Lower Cretaceous
50
Laterally extensive
sands, interbedded
Major regional aquifer.
with thin layers of
clay.
Alternating confining
Sand layers
beds and sandy aquifers. interbedded with
Major aquifers at Chalk
thick clay and silt
Point at 850 and 1000layers.
Upper Patapsco
Formation
600
Lower Patapsco
Formation
>500
Alternating confining
beds and sandy aquifers.
Major aquifer at Chalk
Point at 1500-foot sand.
Sand layers
interbedded with
thick clay and silt
layers.
540
Alternating sands and
clay confining beds.
Thicker sands toward
top of aquifer, minor
sands toward bottom.
Sand layers
interbedded with
thick clay layers.
Progressively more
clay toward the
bottom of formation.
Patuxent Formation
After Mack 1976, 1983.
The Calvert Formation, which underlies the Upland Deposits, consists of
sediments deposited in deep marine waters during the Miocene Epoch
(Cleaves, et al. 1968; Glaser 2003). The sediments consist of largely
variable clayey, very fine- to fine-grained sand and silt with diatomaceous
silt and trace amounts of clay. The base of the formation is a bed of
diatomaceous silt, up to 10 feet thick with the upper portion consisting of
relatively homogeneous sand and silty sand. The deposits are commonly
green to olive-gray in color and weather to a pale-gray, tan brown, yellow,
or orange hue. The maximum thickness of the formation is around 100
feet (Cleaves, et al. 1968).
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3.2
WATER RESOURCES
3.2.1
Hydrogeologic Units
Mattawoman installed nine soil borings at the site in the Quaternary
Upland Deposits to depths ranging between 25 and 30 feet, and collected
continuous soil samples between five feet and the bottom of the boring to
log the lithology (Trihydro 2014). The Upland Deposits at the site are
composed of clay, silt, sand, and gravel. Figure 3-1 presents the geologic
cross sections A-A’ and B-B’ based on the lithology of the materials found
in the soil borings. Based on the lithology obtained from the soil borings,
three distinct strata were identified within the Upland Deposits beneath
the Mattawoman site, in descending order:
•
•
•
10 to 12 feet of clayey sand to silty clay;
16 to 18 feet of silty sand and gravel; and
Sandy clay below the silty sand and gravel layer to a depth of at
least 35 feet.
As shown in cross-section A-A’, the composition of the geologic materials
is consistent across the 90-acre property. Further, the same geologic
materials were found at identical depths on the Brandywine DRMO
Superfund site property, and beyond the property.
The Miocene Calvert Formation of the Chesapeake Group lies
immediately beneath the Upland Deposits and consists of clay with minor
amounts of silt, clayey sand, and silty clay with interbedded fine sand. At
the Mattawoman site, based on the results from Mattawoman boring SB-5,
the top of the Calvert Formation is estimated to be below 35 ft. bgs. SB-5
was completed at a depth of 35 feet and did not encounter the distinctive
composition and color of the Calvert Formation.
The Nanjemoy Formation lies beneath the Calvert Formation and consists
of interbedded fine sand, silt, sandy silt, and silty clay. The Marlboro Clay
underlies the Nanjemoy Formation and consists of dense reddish-brown
silty clay. The Aquia Formation lies beneath the Marlboro Clay and
consists of greenish-gray glauconitic sand and silt, and is located 350 bgs.
3.2.2
Groundwater Conditions
Mattawoman installed seven monitoring wells in the nine soil borings
(MW-1 through MW-7). The wells were installed to a depth of 25 feet and
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constructed with 2 inch diameter PVC, with 20 feet of 0.010 inch slotted
well screen. The top of casing well elevations were surveyed to a relative
elevation to establish a temporary datum.
Groundwater occurs under unconfined or water table conditions in the
Upland Deposits. On 10 September 2014, depth to groundwater
measurements were collected from the seven onsite wells. The depth to
the water table below the ground surface ranged from approximately 6 to
12 feet bgs across the site.
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Figure 3-1
MD PPRP
Geologic Cross-Sections A-A’ and B-B’
3-6
Figure 3-2 presents a conceptual groundwater elevation contour map for
the Brandywine Formation generated from the 25 September 2014 water
level elevation data collected by Mattawoman from the seven on-site
wells, and the 23 September 2014 water level elevation data collected from
monitoring wells located on and near the Brandywine DRMO site. The
map presents conceptual groundwater contours because: 1) the water
level elevation data collected by Mattawoman were not collected from
wells surveyed to a mean sea level datum, so while the contours for the
respective sites are accurate, the interpretation of the groundwater
contours between the Mattawoman and DRMO sites is conceptual; and 2)
the water levels for both sites were collected a few days apart and
therefore are not synoptic.
Figure 3-2
Conceptual Groundwater Contours for the Brandywine
Formation, September 2014
The groundwater contours for the Mattawoman site indicate an apparent
groundwater flow divide present between the proposed power block
where dewatering will occur and the northern portion of the site. In
general, groundwater flow in the vicinity of the construction area is
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3-7
towards the southeast, and surficial groundwater flow in the vicinity of
the northern portion of the site is towards the northwest. The apparent
groundwater divide is created by the presence of the headwaters to the
unnamed tributary to Mattawoman Creek. Based on the conceptual
groundwater flow contours shown in Figure 3-2, groundwater flow is
southward from the southern end of the Brandywine DRMO site towards
the Mattawoman site; however, groundwater discharges to the unnamed
tributary to Mattawoman Creek and does not continue southward toward
the power block.
With respect to the groundwater flow contours on the Brandywine DRMO
site, the September 2014 groundwater flow contours indicate the presence
of a hydrologic divide on the DRMO property. Groundwater flow is
interpreted to be both southward toward the Mattawoman site and
northeast. A groundwater recovery trench that operated on the
Brandywine DRMO site was shut down in 2013 and the groundwater flow
pattern has recovered to static conditions measured prior to the
installation and operation of the recovery trench. The presence of the
groundwater divide on the Brandywine DRMO site is consistent with the
interpretation provided by URS (2006) based on groundwater elevation
data collected in August 2003. The groundwater divide on the
Brandywine DRMO site reflects the location of the site between three
watersheds (Figure 3-3). Further detail regarding the interpretation of
groundwater flow on the Brandywine DRMO site is described in
Appendix F.
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Figure 3-3
Watershed Boundaries on the Brandywine DRMO Site
Mattawoman conducted short-term aquifer drawdown tests (Trihydro,
2014) to measure the hydraulic conductivity of the water-bearing zone of
the Brandywine Formation. The aquifer tests were initiated on 9
September 2014. Five wells were tested using a submersible pump and
pressure transducer/data logger. The results of the tests and analysis
conducted to calculate the hydraulic conductivity is described further in
Appendix E. The results of the drawdown analyses estimated site-specific
hydraulic conductivity values that range from about 0.2 to 13.2 ft/day,
which are within the range of regional values. The average hydraulic
conductivity value was roughly 3.8 ft/day.
Mattawoman described the results of the investigation of groundwater
quality conditions on the northern part of the Mattawoman site in
Mattawoman’s response to PPRP Data Request 8-2. In July 2012,
Mattawoman conducted a site assessment to evaluate any potential
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contamination of soils and groundwater within the Mattawoman site as a
result of past spills under previous ownership and the nearby Brandywine
DRMO Superfund Site. Four temporary groundwater monitoring wells
were installed for groundwater sampling. Groundwater samples were
collected and submitted for analysis using the U.S. Environmental
Protection Agency (EPA) Method 8260B for volatile organic compounds
(VOCs); EPA Method 8270C for polycyclic aromatic hydrocarbons (PAHs)
and semivolatile organic compounds (SVOCs); EPA Method 8082 for
polychlorinated biphenyls (PCBs); and EPA Method 6020 for priority
pollutant metals arsenic, cadmium, chromium, lead, and mercury. The
analytical results did not identify contaminants of concern associated with
the Brandywine DRMO site on the Mattawoman site, or any other
anthropogenic impacts to groundwater quality.
3.2.3
Groundwater Use in the Vicinity of the Mattawoman Site
There is no current on-site use of groundwater on the Mattawoman Site,
nor does Mattawoman propose to use groundwater to support the
operation of the power plant. Water and sewer service in the vicinity of
the Mattawoman site is provided to Prince George’s County residents by
the Washington Suburban Sanitary Commission (WSSC) or through
individual wells and septic systems. According to the adopted 2008
Prince George’s County water and sewer plan, the Mattawoman Site is
located within the sewer and water service envelope. Furthermore, the
Mattawoman Site is located in sewer and water Categories S-3 and W-3,
respectively, according to the Prince George’s County Description of the
Site and surrounding areas (Mattawoman 2013).
However, the residential properties that surround the Site, including the
properties on Brandywine Road, Tower Road, Old Indian Head Road and
North Keys Road, rely on individual wells for a potable water supply. A
well inventory obtained from the MDE indicates that the depths of wells
positively identified to be located on surrounding properties range from
324 to 535 feet below ground surface, suggesting that the majority of wells
tap the Aquia and Magothy aquifers (Figure 3-4). However, a number of
properties in the vicinity of the Site appear to have wells with depths
ranging from 25 to 35 feet below ground surface, indicating these wells are
completed in the Upland Deposits. Additionally, there are likely older
homes with wells that pre-date the well permitting process and are not
included in the well inventory database. Note the MDE WMA well
permit database typically does not include street addresses for the
permits, making it difficult to locate the precise location of a residential
MD PPRP
3-10
well. Thus, there is not complete information regarding the types of wells
used on the nearby properties.
Figure 3-4
Groundwater Users in the Vicinity of the Mattawoman Site
The Brandywine DRMO site is not a groundwater user per se, but does
represent an area where use of groundwater has to be managed to ensure
that the ongoing remediation and institutional control boundary (shown
in Figure 3-2) is not impacted. Detailed analysis regarding the potential
for the construction dewatering to impact the Brandywine DRMO
remediation is included in Appendix F.
3.3
SURFACE WATER RESOURCES
The Project site itself is located within the upper reaches of the
Mattawoman Creek watershed. An approximately 10-acre stormwater
pond was constructed by the previous owner of the Project site to
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3-11
accommodate potential site development for a solid waste recycling
facility, which was never built. The pond is located in the southwestern
corner of the site and will be incorporated into the stormwater
management (SWM) plan as the Project site’s detention pond for the
proposed power plant. The pond includes a discharge control structure
that drains to an unnamed tributary of Mattawoman Creek. The
unnamed tributary extends onto the Mattawoman site. The unnamed
tributary drains into Mattawoman Creek 3,000 feet southwest of the
Mattawoman site.
3.4
CLIMATOLOGY AND AIR QUALITY
3.4.1
Weather and Climate
This discussion of the climatology in the area of the Mattawoman Project
is based on summarized data observed at the Reagan National Airport
(KDCA). KDCA is the closest National Weather Service (NWS) station to
the proposed Project Site, located approximately 24 kilometers (<15 miles)
to the northwest of the Site.
The climate in southern Maryland is classified as temperate with maritime
influences from the Atlantic Ocean and Chesapeake Bay. Based on a 69year period of records through 2014, the average annual temperature in
the region is 57.9 degrees Fahrenheit (°F) (NCDC, 2014). Summers are
warm and relatively humid, and winters are generally mild because of the
warming influence of the Gulf Stream. The lowest mean daily minimum
temperature, 28.4°F, occurs in January; the highest mean daily maximum
temperature, 88.1°F, occurs in July.
Rainfall distribution throughout the year is generally uniform; however,
the greatest intensities are confined to the late spring and summer, the
season for severe thunderstorms. Average annual precipitation is 39.74
inches.
3.4.2
Ambient Air Quality
Air quality measurements have been taken at thousands of monitoring
stations across the country for several decades, producing data that
reflects ambient air concentrations of the “criteria” pollutants, nitrogen
oxides (NOx), sulfur dioxide (SO2), particulate matter (PM10 and PM2.5),
ozone (O3), carbon monoxide (CO), and lead (Pb). State, local and tribal
air quality agencies operate and maintain most of the stations following
MD PPRP
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nationally consistent procedures established by the EPA. Data are
routinely reported to and summarized by EPA in its Air Quality System
(AQS) that can be accessed on the internet 1.
The pollutant monitors are situated above the ground to represent the
human breathing height. If ambient air quality monitoring indicates that
the concentration of a pollutant exceeds a National Ambient Air Quality
Standard (NAAQS) in any area of the country, that area is classified as a
“nonattainment area” for that pollutant, meaning that the area is not
meeting the NAAQS. Conversely, any area in which the concentration of
a criteria pollutant is below the NAAQS is classified an “attainment area”
indicating that the NAAQS are being met.
The attainment/nonattainment designations are made by states and EPA
on a pollutant-by-pollutant basis. Therefore, the air quality in an area may
be designated attainment for some pollutants and nonattainment for other
pollutants at the same time. For example, many cities are designated
nonattainment for ozone, but are in attainment for the other criteria
pollutants.
Since the late 1980s, the NAAQS for particulate matter covered “PM10,”
which represents PM less than 10 microns in diameter. In 1997, EPA
revised the NAAQS for PM and added a standard for a new form of PM
known as PM2.5, PM that is less than 2.5 microns in diameter. Further
revisions to the PM2.5 NAAQS were published in 2006 (24-hour NAAQS)
and in 2012 (annual NAAQS). PM2.5, or “fine particulates,” is of concern
because the particles’ small size allows them to be inhaled deeply into the
lungs and these fine particles contribute to haze and other air quality
issues. In December 2014, EPA published updated designations of PM2.5
for the 2012 annual PM2.5 standard.
EPA and states make attainment designations based on air quality
surveillance programs that measure pollutants in a network of nationwide
monitoring stations. Historically, these networks were known as the State
and Local Air Monitoring Stations (SLAMS), National Air Monitoring
Stations (NAMS), and Photochemical Air Monitoring Stations (PAMS)
(EPA, 1998). The SLAMS network designation is still maintained;
however, NAMS and PAMS have been folded into the National Core
1
http://www.epa.gov/airdata/
MD PPRP
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(NCore) Multipollutant Network and the PM2.5 Chemical Speciation
Network that provide specialized measurements focused on
understanding the underlying causes of (and potential solutions to)
nonattainment of the ozone and PM2.5 NAAQS.
EPA’s six stated objectives for the monitoring network design for the
SLAMS are to (EPA, 1998):
•
Determine highest concentrations expected to occur in the area
covered by the network;
•
Determine representative concentrations in the areas of high
population density;
•
Determine the impact on ambient pollution levels of significant
sources or source categories;
•
Determine general background concentration levels;
•
Determine the extent of Regional pollutant transport among
populated areas, and in support of secondary standards; and
•
Determine the welfare-related impacts in more rural and remote
areas (such as visibility impairment and effects on vegetation).
EPA further explains that SLAMS monitors are intended to be located so
that the samples they collect are representative of air quality over the
entire area they are intended to cover. The EPA established “spatial scales
of representativeness” to ensure that monitoring of specific pollutants is
appropriate and representative. The scales of representativeness include
microscale, middle scale, neighborhood scale, urban scale, and regional
scale. The scale takes into consideration such factors as local terrain,
pollutant-specific criteria, and population density. EPA reviews the
program annually to “…improve the network to ensure that it provides
adequate, representative, and useful air quality data” (EPA, 1998).
In summary, EPA and state air agencies have established a monitoring
network designed to allow collection of monitoring data sufficient for
EPA to determine ambient air quality of criteria pollutants. The
monitoring data are used to determine background ambient
concentrations of criteria pollutants, and to classify all areas of the county
as attainment or nonattainment of the NAAQS.
MD PPRP
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All of the State of Maryland, including Prince George’s County, is in
attainment of the NAAQS for all criteria pollutants with the exception of
ozone. Some counties in Maryland are designated ozone attainment areas
and some are nonattainment areas; however, because ozone is a regional
issue, EPA treats the Northeastern United States (from northern Virginia
to Maine) as an ozone nonattainment area known as the Northeast Ozone
Transport Region.
Prince George’s County is designated a “moderate” ozone nonattainment
area (on a scale that ranges from worst to best air quality of extreme –
severe – serious – moderate – marginal). EPA recently changed the air
quality designation of Prince George’s County with respect to PM2.5
NAAQS from nonattainment to attainment. On October 6, 2014, EPA
issued a final rule redesignating the Washington DC area (which includes
Prince George’s County) to attainment for the 1997 annual PM2.5
NAAQS. The EPA final rule became effective on November 5, 2014.
3.5
3.5.1
Project Site
The proposed Project Site is an 88-acre plot situated in a developed
portion of Prince George’s County. It is bordered on the north by
Brandywine Road, on the south by a heavily forested 1,635-acre tract of
land owned by the US Government, on the east by a CSX Transportation,
Inc. (CSXT) rail line, and on the west by an automotive salvage yard.
Most of the Site was cleared and graded by a previous owner, who also
developed several access roads across the property. This previous owner
also had a stormwater management (SWM) system constructed, including
a stormwater pond located in the southwest corner of the Site. A large
berm is located on the southeast corner of the cleared area of the Site, near
the terminus of the access road. The majority of the Site is open land or
gravel road (72%) and the SWM pond covers 12% of the Site. Upland
mixed forest accounts for 4% of the Site and wetlands account for 12% of
the area (see Figure 2-2 for general Site layout).
3.5.1.1
Surface Waters and Aquatic Resources
The Project Site is located in the headwaters area of the Mattawoman
Creek watershed, which ultimately drains into the Potomac River at
Indian Head, Maryland. Mattawoman Creek is a Maryland DNRdesignated Stronghold Watershed that contains numerous
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environmentally sensitive areas and is an important biodiversity center
for the State. A more detailed description of the Mattawoman Creek
watershed is in Section 3.4.2. Aquatic resources on the Site include an
approximately 10.3-acre stormwater pond constructed by the previous
owner. This pond is located in the southwestern corner of the site and
will be incorporated into the SWM plan as the Project’s detention pond for
the proposed power plant. The pond includes a discharge control
structure that drains to an unnamed and intermittently flowing tributary
to Mattawoman Creek (Mattawoman, 2013). This tributary also drains
nearby herbaceous and forested wetlands, which is highlighted in Figure
3-5.
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Figure 3-5
Land Use and Limits of Disturbance on the Mattawoman Energy Center Project Site
Source: Mattawoman’s Response to PPRP Data Request No. 12-15, Attachment 12-15-1.
MD PPRP
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3.5.1.2
Vegetation and Land Cover
Most of the Site has been previously cleared and stabilized with early
successional grasses and legumes such as bent grass, lespidiza, fox tail,
panic grass, and broomsedge. This vegetation community has a low
diversity and structural complexity, but may support communities of
small mammals or ground nesting birds.
There are natural vegetation communities associated with the wetlands
onsite, and there has been some supplemental tree planting to satisfy
county forest conservation plan requirements of the previous property
owner. The Tree Conservation Plan for the Site was approved by the
Maryland National Capital Park and Planning Commission (M-NCPPC),
which required 8.65 acres of afforestation and 7.66 acres of woodland
preservation. Split rail fencing was also installed to delineate and protect
these areas. Approximately 4% of the Project Site is comprised of upland
mixed forest. Narrow strips of forest are located along the southern
boundaries of the Site. There is also an area of upland planted forested on
the north side of a wetland that bisects the north-central part of the Site.
The dominant vegetation species in this community include white oak,
red oak, red maple, sweet gum, Virginia pine, red cedar, Japanese
honeysuckle, and blackberry. The forested areas on the Site are integral
with extensive surrounding forests and buffer the forest interior regions of
those forests as well as provide a connecting corridor to an otherwise
isolated forest patch to the north and west of the Site. Loss of the onsite
forest areas would diminish both the Green Infrastructure Network and
the amount of Forest Interior Dwelling Species (FIDS) habitat, and would
have a negative impact on the species that use these resources.
The approximately 10 acre SWM pond on the Project Site is relatively
shallow and largely vegetated with herbaceous wetland species including
cattails, soft rush, wool grass, and various other sedges and rushes. There
is a much smaller pond on the eastern side of the Site that appears to
function only as a sediment trap (Mattawoman, 2013).
3.5.1.3
Wetlands
A Project Site wetlands delineation was performed by a previous owner to
obtain approvals and permits to construct the access road. That
delineation was checked by a Mattawoman contractor in a March 2013
field survey and found to be still largely accurate (Mattawoman, 2013);
however, several additional wetland areas located along the western
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property boundary were delineated by Environmental Consulting &
Technology, Inc. (ECT) on behalf of Mattawoman.
These additional wetlands areas are primarily forested wetlands
associated with the unnamed tributary to Mattawoman Creek and the
wetland that bisects the north-central part of the Site. Dominant
vegetation species include red maple, pin oak, willow oak, sweetgum,
loblolly pine, high bush blueberry, greenbrier, and Japanese stilt grass.
Several wetland areas are vegetated primarily by herbaceous species.
These areas include natural wetlands, as well as two drainages that
appear to be manmade and associated with the constructed SWM system.
Dominant vegetation includes cattails, common reed, reed canary grass,
Japanese stilt grass, wood grass, soft rush, caric sedges, greenbrier, and
blackberry.
Two of the headwaters tributaries of Mattawoman Creek originate in a
large forested wetland complex (approximately 100 acres in size)
immediately east of the Project Site. Although the edge of this complex is
separated from the Site by a railroad ROW, it could be affected by any
airborne construction dust, emissions from operations of the plant, or
deposition of combustion or cooling system byproducts.
3.5.1.4
Wildlife and Rare, Threatened and Endangered Species
Mattawoman initially conducted field surveys for wildlife species on the
Project Site in November 2011 and March 2013. Few species were found
because of the season. The Site is within a large area that is classified as
potential FIDS habitat by DNR. Although the Site itself has been cleared,
the large forested tracts required by FIDS to breed successfully surround
the Site, except along the western boundary. The Site forms an edge
habitat wedge that may allow invasive species to penetrate into interior
areas, reducing their habitat value.
The DNR Wildlife and Heritage Service (WHS) stated in a letter (L. Byrne
to V. Brueggemeyer, December 21, 2011) that no State or Federal rare,
threatened or endangered (RTE) species are known to occur within the
Site boundary, but there are database records for four State-listed plant
species in close proximity to the Site: racemed milkwort (threatened),
sandplain flax (threatened), Midwestern gerardia (endangered), and
Buxbaum’s sedge (threatened). None of these species were observed on
or near the Site during the 2011 and 2013 site visits, or during an
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additional survey that was conducted by ECT on behalf of Mattawoman
in September/October of 2014.
3.5.2
Proposed linear facilities associated with the Project include an
approximately 10-mile-long reclaimed wastewater pipeline to bring
treated effluent from Piscataway WWTP, an approximately 7.4-mile-long
natural gas pipeline, and a 2.3 mile generator lead line extending from the
power plant site north to PEPCO’s Burches Hill to Talbert 230-kV PEPCO
transmission line. Mattawoman will also construct a substation at this
interconnection point, linear routes are shown in Figure 3-6.
Mattawoman's June 2014 Substitute Appendix A-1 Filing and January
2015 Supplemental Filing, indicate that the proposed reclaimed water
pipeline will be built within existing roadbeds for most of its length.
Leaving the Project Site, it traverses west along Brandywine Road for
approximately 1.8 miles to Accokeek Road. From there, it follows
Accokeek Road approximately 5.8 miles to Barry Road. The route then
turns northwest and follows Barry Road approximately 1.2 miles to
Farmington Road, where it turns south and runs along the north side of
Farmington Road approximately 0.7 mile across Indianhead Highway and
into the Piscataway WWTP.
The proposed gas pipeline route as described in the Linear Facilities ERD
(June 2014 Substitute Appendix A-1 and January 2015 Supplemental
Filing) exits the eastern boundary of the Project Site, crosses the CSXT
railroad track, and then continues southeast for approximately 1.2 miles
along the east side of the railroad track within a Southern Maryland
Electric Cooperative (SMECO) easement. At that point, it crosses back
under the railroad track and runs southeast through new right of way
approximately 250 feet from the CSXT ROW to the intersection of
PEPCO's Talbert-Morgantown transmission line ROW. The pipeline then
runs south/southwest along the western side of this ROW for about 5
miles, then veers southeast through a new ROW for about a mile to an
existing natural gas interstate transmission pipeline. This route crosses
through Cedarville State Forest and the watershed of Jordan Swamp, a
Non-Tidal Wetland of Special State Concern (NTWSSC).
MD PPRP
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Figure 3-6
MD PPRP
Watersheds in Vicinity of Proposed Site
3-21
The proposed 230-kV generator lead line will interconnect to PEPCO’s
existing Burches Hill to Talbert 230-kV transmission line located
approximately 2.5 miles north of the power plant Site. Mattawoman will
construct and own the generator lead line to the point of interconnection.
The proposed route proceeds in a northwesterly direction adjacent to the
ROW for Brandywine Road. The route makes a couple of turns and
proceeds northeast for approximately 2.3 miles along the CSXT railroad
ROW, within the 69-kV SMECO corridor, until it reaches the PEPCO 230kV transmission line. This segment of the route also crosses an existing
PEPCO 500-kV line, which traverses the route in an east/west direction.
Mattawoman is in the process of negotiating an agreement with SMECO
under which SMECO will relocate the 69-kV sub-transmission line 39 ft
east of its current location within the SMECO easement. Mattawoman
plans to purchase land adjacent to the SMECO ROW, clear the existing
vegetation and pay to rebuild the SMECO line.
Vegetation along the generator lead line corridor and substation consists
of upland forest and open land, a portion of which is cleared/maintained
right-of-way. Common tree species present along the generator lead line
include white oak (Quercus alba), southern red oak (Q. falcata), blackjack
oak (Q. marlandrica), red maple (Acer rubrum), Virginia pine (Pinus
virginiana), sweetgum (Liquidambar styraciflua), red cedar (Juniperus
virginiana), and American holly (Ilex opaca). Shrubs and understory
species include high bush blueberry (Vaccinium corymbosum), greenbriar
(Smilax spp.), Japanese honey suckle (Lonicera japonica), and multiflora
rose (Rosa multiflora).
The proposed substation site is located on Cherry Tree Crossing Road,
adjacent to the PEPCO 230-kV transmission line corridor. The site
contains approximately 8 acres of predominately upland forest (Figure 37). The substation is proposed to be located in the northeastern portion of
the site. Approximately 6 acres of land will be used for the substation and
the tie-in of the generator lead line, which is defined as the approximately
300-ft north-northwestern most portion of the generator lead line.
Forested wetlands associated with an unnamed headwater stream to
Piscataway Creek are also present on the western side of the substation
site.
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Figure 3-7
Proposed Substation Site Located on Cherry Tree Crossing
Road, adjacent to the PEPCO 230-kV transmission line
corridor
Source: Mattawoman April 2015 Substation Supplemental Filing
The area in which biological resources may be affected by the
Mattawoman Project is bounded by the Potomac and Patuxent Rivers.
The Project Site is located very near the center of this area, where six
watersheds or drainage areas originate (see Figure 3-6). In this nearly flat
headwaters area, water can flow in almost any direction, with surface
drainage patterns frequently determined by the built environment.
Western Branch, Patuxent River Middle, and Patuxent River Lower
watersheds all drain into the Patuxent Scenic River 2, although Western
2 The Patuxent River watersheds drawn on the map are composed of the western
subwatersheds of the complete Patuxent River watersheds defined by Maryland.
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Branch and Patuxent River Lower will probably not receive any runoff
from the Project Site. The remaining three watersheds – Piscataway
Creek, Mattawoman Creek, and Zekiah Swamp – which will be affected
by the Project facilities, drain to the Potomac River. While not all six
watersheds are subject to direct impacts from the Project, they form a
single regional ecological system in which links between watersheds may
cause indirect impacts.
The proposed water pipeline affects the Mattawoman Creek and
Piscataway Creek watersheds, while the proposed natural gas pipeline
affects the Mattawoman Creek and Zekiah Swamp watersheds, and the
generator lead line and substation affect the border of Patuxent River
middle and Piscataway Creek watershed. Table 3-2 summarizes the
sensitive features in the four watersheds. Sections 3.4.2.1 through 3.4.2.4
review the detailed nature of each watershed including the general
distribution of land use and resource areas (such as Green Infrastructure
or Tier II streams), as well as the sensitive species present and the overall
contribution of the affected watersheds to biodiversity and ecosystem
preservation within the State. Section 3.4.2.5 discusses how the linear
facilities affect the resources in these watersheds.
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Table 3-2
Watershed
Sensitive Resources in the Four Watersheds in Southern Maryland
Scenic
Stronghold
Tier II Streams
Bionet
Green
River
Watershed Species
Area
Infrastructure
Mattawoman
Creek
Fish Species of Greatest
Conservation Need (SGCN):
Warmouth (Lepomis gulosus)
Reptile and amphibian SGCN: 3
known.
Zekiah
Swamp
Largest
tributary to
the
Wicomico
Scenic
River
Fish SGCN: Least Brook
Lamprey(Lampetra aepyptera),
Warmouth (Lepomis gulosus),
and Bluespotted Sunfish
(Enneacanthus gloriosus)
known.
State-listed threatened species:
American Brook Lamprey
(Lampetra appendix), Comely
Shiner (Notropis amoenus)
Piscataway
Creek
Patuxent
River
Middle
Flier (Centrarchus macropterus)
Patuxent
Scenic
River
known.
American Brook Lamprey
(Lampetra appendix)
Mattawoman Creek 1, Old
Woman’s Run 1, Old
Woman’s Run 2,
Mattawoman Creek UT 1,
Mattawoman Creek UT 2,
Mattawoman Creek UT 3
58% of
watershed
Corridors: 4% of
watershed
Zekiah Swamp Run 1, Wolf
Den Branch 1, Zekiah
Swamp Run 6, Zekiah
Swamp Run 2, Zekiah
Swamp Run UT 2, Mill Dam
Run 1, Zekiah Swamp Run
3, Zekiah Swamp Run UT 3,
Piney Branch 1 Charles
County, Zekiah Swamp Run
UT 1, Zekiah Swamp Run 5,
Smoots Pond Run 1
Piscataway Creek 1 and
Piscataway Creek 2
54% of
watershed
Hubs: 55% of
watershed
Corridors: 6% of
watershed
Wetlands
of Special
State
Concern
SSPRA
(Sensitive
Species
Project
Review Area)
<1% of
watershed
50% of
watershed
9% of
watershed
38% of
watershed
<1% of
watershed
16% of
watershed
5% of
watershed
16% of
watershed
Hubs: 50% of
watershed
34% of
watershed
Corridors: 5% of
watershed
Hubs: 36% of
watershed
Mattaponi Creek UT 1
8% of
watershed
Corridors: 8% of
watershed
Hubs: 31% of
watershed
Fish SGCN: Bluespotted Sunfish
(Enneacanthus gloriosus), Least
Brook Lamprey (Lampetra
aepyptera), Rosyside Dace
(Chaenobryttus gulosus), and
Warmouth (Lepomis gulosus)
Reptile and amphibian SGCN:
1 known
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3.5.2.1
Mattawoman Creek
Mattawoman
Creek is a
tributary of the
Potomac River
that drains
portions of
Prince George’s
and Charles
Counties. The
land use in the
60,300-acre
watershed is
predominantly
forested,
followed by
urban
development.
Protected lands
in the
Mattawoman
Creek watershed
include portions
of Chapman
State Park, Smallwood State Park, the Mattawoman State Natural Environmental
Area, and Myrtle Grove Wildlife Management Area. Protected lands (County,
State, or Federally Protected) account for 14% of the land area in the watershed.
Green Infrastructure Corridors account for 4% of the watershed area; while
Green Infrastructure Hubs account for 55% of the land area.
Mattawoman Creek contains six Tier II stream segments: Mattawoman Creek 1,
Old Woman’s Run 1, Old Woman’s Run 2, Mattawoman Creek UT 1,
Mattawoman Creek UT 2, and Mattawoman Creek UT 3. It is a Stronghold
Watershed, known to contain one fish Species of Greatest Conservation Need
(SGCN) and three amphibian and reptile SGCN (Table 3-2). Fifty percent (50%)
of the watershed is designated Sensitive Species Project Review Area (SSPRA)
and 58% of the watershed is in a designated Bionet diversity zone. In addition,
Kazyak et al. (2005) ranked Mattawoman Creek 33rd on the list of 84 Maryland
watersheds for biodiversity importance.
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3.5.2.2
Zekiah Swamp
Zekiah Swamp is the main
tributary of the Wicomico
River, draining portions of
Prince George’s and
Charles Counties. The
land use in the 69,770-acre
watershed is
predominantly forested,
followed by agriculture.
Protected lands in the
Zekiah Swamp watershed
include Zekiah Swamp
Natural Environmental
Area and Cedarville State
Forest. Protected lands
(County, State, or
Federally Protected)
account for 7% of the land
area in the watershed.
Green Infrastructure
Corridors account for 6%
of the watershed area;
while Green Infrastructure Hubs account for 50% of the land area.
Zekiah Swamp Run is a tributary to the Wicomico River, which was designated
as a Maryland Scenic River by the Maryland legislature. A Scenic River
Management Plan for the Wicomico River watershed, including Zekiah Swamp,
was developed in 1994. Zekiah Swamp contains 12 Tier II stream segments:
Zekiah Swamp Run 1, Wolf Den Branch 1, Zekiah Swamp Run 6, Zekiah Swamp
Run 2, Zekiah Swamp Run UT 2, Mill Dam Run 1, Zekiah Swamp Run 3, Zekiah
Swamp Run UT 3, Piney Branch 1 Charles County, Zekiah Swamp Run UT 1,
Zekiah Swamp Run 5, and Smoots Pond Run 1.
Zekiah Swamp is a Stronghold Watershed, known to contain three fish SGCN
and five amphibian and reptile SGCN (Table 3-2). Thirty-eight percent (38%) of
the watershed is designated Sensitive Species Project Review Area (SSPRA) and
54% of the watershed is in a designated Bionet diversity zone. In addition,
Kazyak et al. 2005 ranked Zekiah Swamp first on the list of 84 Maryland
watersheds for biodiversity importance.
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3.5.2.3
Piscataway Creek
Piscataway Creek is
a tributary of the
Potomac River that
drains portions of
Prince George’s
County. The land
use in the 43,579acre watershed is
predominantly
forested (48%),
followed by urban
development (34%).
Sixteen percent
(16%) of the land
area is accounted for
by agriculture and
2% of the land is
wetlands.
Seventeen percent
(17%) of the
watershed is
impervious surface (i.e. roads, buildings, parking lots, and other paved surfaces).
Protected lands in the Piscataway Creek watershed include Piscataway Creek
Stream Valley Park. Protected lands (County, State, or Federally Protected)
account for 14% of the land area in the watershed. Green Infrastructure
Corridors account for 5% of the watershed area; while Green Infrastructure Hubs
account for 36% of the land area.
Piscataway Creek contains two Tier II stream segments: Piscataway Creek 1 and
Piscataway Creek 2. It is a Stronghold Watershed, known to contain two Statelisted threatened fish species and five amphibian and reptile species of Greatest
Conservation Need (Table 3-2). Sixteen percent (16%) of the watershed is
designated Sensitive Species Project Review Area (SSPRA) and 34% of the
watershed is in a designated Bionet diversity zone. In addition, Kazyak et al.
2005 ranked Piscataway Creek 15th on the list of 84 Maryland watersheds for
biodiversity importance.
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3.5.2.4
Patuxent River Middle (Western Shore)
The middle pA portion of the Patuxent
River drains Prince George’s
and parts of Anne Arundel
Counties. The land use in
the 39,804-acre watershed is
predominantly forested,
followed by agriculture and
urban development.
Protected lands in the
Patuxent River Middle
watershed include the
Patuxent River Park.
Protected lands (County,
State, or Federally
Protected) account for 16%
of the land area in the
watershed. Green
Infrastructure Corridors
account for 8% of the
watershed area; while GI
Hubs account for 31% of the
land area.
The Patuxent River was designated as a Maryland Scenic River by the Maryland
legislature. A Scenic River Plan for the Patuxent River has not been developed,
but the Patuxent River Commission (PRC) has developed a Patuxent River Policy
Plan, with an updated draft containing goals for 2015 (Patuxent River). In
addition, there is a Watershed Restoration Action Strategy (WRAS) report for
Western Branch. The WRAS report was developed by Prince George’s County
government, as well as the City of Bowie, in close concert with DNR. The
Patuxent River Middle watershed contains one Tier II stream segment:
Mattaponi Creek UT 1.
Patuxent River Middle is a Stronghold Watershed, known to contain one statelisted threatened species and four fish species of Greatest Conservation Need, as
well as one amphibian and reptile species of Greatest Conservation Need.
Sixteen percent (16%) of the watershed is designated Sensitive Species Project
Review Area (SSPRA) and 8% of the watershed is in a designated Bionet
diversity zone.
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3.5.2.5
Resources Affected by the Linear Facilities and Substation
The proposed reclaimed water and natural gas pipelines for the Project
will cross streams in the Mattawoman Creek, Piscataway Creek, and
Zekiah Swamp watersheds that are upstream of Tier II stream segments of
Mattawoman Creek, Piscataway Creek, Jordan Swamp, and Zekiah
Swamp Run. The water pipeline route crosses two tributaries to
Mattawoman Creek, including Timothy Branch, and four tributaries to
Piscataway Creek, including Burch Branch. The natural gas pipeline route
crosses Mattawoman Creek, two tributaries to Wolf Den Branch, two
tributaries to Zekiah Swamp Run, and three headwater ravines that drain
into Jordan Swamp. Trenching for pipeline installation at any of these
stream crossings will also involve construction in their 100-year
floodplains.
The proposed reclaimed water and natural gas pipeline routes also cross
several non-tidal wetland systems located in Prince George’s County or
Charles County, Maryland. Construction of the water pipeline will have
impacts on a total of 0.23 acres of emergent wetlands and 0.11 acres of
forested wetland through conversion to emergent wetlands (January 2015
Supplemental Filing, Appendix D). The gas pipeline wetland crossings
occur adjacent to or within existing disturbed corridors associated with
the CSXT railroad track, SMECO easement or PEPCO transmission line,
and along the portion of the route that runs parallel to Jordan Swamp, a
NTWSSC, at a distance of 500 to 800 feet, for almost 1 mile.
Approximately 3.6 acres of emergent wetlands, 5.82 acres are forested
wetlands, and 0.04 acres of surface waters will be affected by the gas
pipeline (Mattawoman January 2015 Supplemental Filing, Appendix C).
The water and gas pipeline routes cross several streams located in the
Piscataway Creek, Mattawoman Creek, and Zekiah Swamp watersheds.
The Piscataway watershed contains two State-threatened fish species: the
American Brook Lamprey and the Comely Shiner. The Zekiah Swamp
watershed contains the State-threatened Flier (Table 3-2). These four
watersheds also contain several species designated as Species of Greatest
Conservation Need (SGCN; Table 3-2).
DNR WHS has stated that there were no RTE plant species known to
occur in close proximity to the proposed reclaimed water pipeline route
(WHS 2014). DNR WHS review noted that for the proposed gas pipeline
route, there is a record for the State-listed threatened racemed milkwort
and State-listed threatened Buxbaum’s sedge located within the northern
segment of the Project route, in the existing railroad ROW.
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In addition, there are records for the following RTE plant species known
to occur in close proximity to this Project, near the Brandywine Receiving
Station:
Scientific Name
Carex buxbaumii
Common Name
Buxbaum’s Sedge
State Status
Threatened
Linum intercursum
Sandplain Flax
Threatened
Polygala polygama
Racemed Milkwort
Threatened
Agalinis skinneriana
Midwestern Gerardia
Endangered
Where the Project route crosses State land at Cedarville State Forest, there
are records for RTE species associated with the WSSC associated with
Wolf Den Branch/Zekiah Swamp Run. These species are known to occur
downstream of the Project route and could potentially occur on the route
itself: State-rare deciduous holly and State-endangered kidney-leaf grassof-Parnassus. Also occurring in close proximity to the gas pipeline route,
near the WSSC associated with Jordan Swamp, are multiple records for
the State-rare primrose willow.
Surveys for RTE species, performed by ECT on behalf of Mattawoman in
May/June 2014, did not identify any RTE plant species in either the
reclaimed water or natural gas pipeline routes. However, recommended
survey times for several of the plant species were between August and
October, and additional surveys were recommended for this time period
by DNR WHS; therefore, ECT on behalf of Mattawoman conducted
addition RTE surveys in September and October of 2014. The WHS has
accepted the findings of the rare species survey report, which indicated no
rare species were observed in the Mattawoman Project areas surveyed.
The report also stated that surveys for the spring blooming sedge, Carex
buxbaumii (State Threatened), would be conducted. WHS supports this
additional survey work, and recommended that this survey be done the
first week of June 2015.
Three herbaceous wetlands, two forested wetlands, one stream, and one
pond were delineated within the generator lead line corridor. The
herbaceous wetlands were dominated woolgrass (Scirpus cyperinus), soft
rush (Juncus effuses), smartweed (Polygonum spp.), cattail (Typha latifolia),
spike rush (Eleocharis spp.), wooly sedge (Carex lanuginosa), and reed
canary grass (Phalaris arundinacea). The forested wetland was vegetated
by sweetgum, red maple, and willow oak (Q. phellos). There are no
wetlands of special state concern within the electric generator lead line
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corridor. The generator lead line crosses a tributary to Mataponi Creek,
which ultimately drains into Patuxent River.
A baseline ecological assessment of the revised substation site was
conducted in March 2015. The assessment included vegetation
community mapping, a general wildlife inventory, a wetland and water
body delineation, and a survey for potential listed species habitat or
presence (April 2015 Substation Supplemental Filing). Constructing the
substation and the tie-in will require a permanent loss of approximately
4.6 acres of upland forest, 1.3 acres of open land, and 0.02 acre of forested
wetland. Additional species survey of the revised substation site are
scheduled for June 2015, and the results will be submitted to the Maryland
PSC to update the record (April 2015 Substation Supplemental Filing).
3.6
REGIONAL SOCIOECONOMIC SETTING
Prince George’s County is located within the Baltimore/Washington
corridor. Comprising 482 square miles, the County borders the District of
Columbia to the west and is 37 miles south of Baltimore City. Established
in 1696, Prince George’s County was formed from Calvert and Charles
Counties by an act of the General Assembly. There are 27 municipalities
in Prince George’s County. The oldest, Bladensburg, was incorporated in
1854. Upper Marlboro is the county seat. There are no municipalities in
the southern part of the county.
3.6.1
Population Trends
Prince George’s County’s population was 890,081 in 2013, an increase of
3.1% from April 2010 (Census 2015). In 2009, 26.8% of the population
resided in municipalities (MNCPPC 2010). The population of Prince
George’s County is projected to increase to more than 995,000 by 2040
with much of the growth to be absorbed within the Developing Tier.
There were 329,324 dwelling units in Prince George’s County in 2013, of
which 67.5% were single unit structures. Most housing in the county is
owner-occupied.
The population of Subregion 6 where the facility would be located was
63,155 in 2008, an increase of 5% from 2000. Most of the population
(53,712) resided in the Developing Tier. The subregion’s population is
expected to grow by 24% between 2008 and 2030, to more than 78,000. Of
the approximately 21,000 dwelling units in 2008, 3,325 were in the Rural
Tier (MNCPPC, 2010).
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Brandywine, the community closest to the Mattawoman Energy Center
Project Site, had a population of 1,451 in 2010, but is poised for growth
due to two large mixed-use developments proposed for the area. One, the
Villages at Timothy Branch, would include 1,200 residential units and
305,000 square feet of commercial space. The preliminary plan for this
project was approved by the Prince George’s County Planning Board in
October 2010. Stephen’s Crossing would build 1,400 residential units and
300,000 feet of commercial space. These developments straddle
Brandywine Road at Mattawoman Drive.
3.6.2
Population growth in Prince George’s County has been accompanied by
significant employment growth. Total jobs by place of work exceeded
423,000 in 2010, a number which is expected to grow to more than 519,000
by 2040. The civilian labor force in Prince George’s County was 449,371 in
2010 with an unemployment rate of 7.4% (PGCPD 2011). There were
14,250 private non-farm establishments in the county in 2010 (Census
2012).
Most employed persons living in Prince George’s County (21.4%) are in
educational services, health care, and social assistance with another 15% in
professional, scientific, and management services (Census, 2012). More
than 36,000 county residents were employed in construction in 2010.
More than 57% of the workforce was employed in jobs outside the county
in 2010. The University System of Maryland is the county’s largest
employer (16,014 in 2010), followed by Joint Base Andrews 3 (8,473) and
the Internal Revenue Service (5,539).
In the vicinity of Brandywine, major employers include the Joint Base
Andrews Globecom Receiver Site, several auto salvage establishments and
big-box retailers at the Brandywine Crossing shopping center (MNCPPC
2011).
Median household incomes in the county are comparable to Maryland as
a whole. In 2010, median household income was $69,947 (2010 dollars)
compared to $69,272 for the State (PGCPD 2011).
3
Joint Base Andrews is a military facility under the jurisdiction of the United States Air Force,
formed from the 2009 merger of Andrews Air Force Base and Naval Air Facility Washington.
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3.6.3
Land Use and Zoning
The Site for the proposed facility lies within the Subregion 6 planning
region which occupies the southeastern portion of Prince George’s
County. While hosting a major military facility in Joint Base Andrews and
an attendant military-industrial complex, Subregion 6 is the most rural
part of the county with a significant amount of land in agriculture or
within environmentally sensitive areas.
Land development in Prince George’s County is guided by Plan Prince
George’s 2035 (MNCPPC 2014), an update to the 2002 Prince George’s
County Approved General Plan (MNCPPC 2002a), adopted by the Prince
George’s County Council in May 2014. The plans provide policy guidance
for major land use elements including environmental infrastructure,
transportation, public facilities, economic development, and historic
preservation. In addition, the Approved Subregion 6 Plan and Proposed
Sectional Plan Amendment recommends goals, strategies and actions for
guiding land use, zoning, rural preservation, transportation, historic
preservation, and other development activities within the region
(MNCPPC 2009). Of other plans that address specific development issues
within the county, three are within the Project’s area of potential effect
(APE). The Brandywine Revitalization and Preservation Study (MNCPPC
2011) focuses on enhancements to preserve the character of the
community in the face of rapid suburban development approaching from
the west. The Joint Base Andrews Joint Land Use Study (MNCPPC 2009b)
addresses encroachment issues and recommends policies for guiding
future development in the vicinity of the military facility. Finally, the 2009
Subregion 5 Plan and Proposed Sectional Plan Amendment recommends
goals and zoning changes to an area that includes part of Brandywine and
major transportation routes that would be affected by the Project
(MNCPPC 2009c).
In Prince George’s County, land use falls within one of three policy areas:
Developed Tier, Developing Tier, and Rural Tier. While the Developed
Tier, located substantially within the Capital Beltway, contains more than
half the county’s population and much of its economic activity, the
Developing Tier encompasses much of the county’s land and has
experienced rapid suburban expansion and employment growth over the
past two decades. The Rural Tier comprises the eastern and southern
portions of the county and contains most of the county’s remaining farms
and environmentally sensitive areas. Parts of the Developing and Rural
tiers are within Subregion 6. The Project would be located within Tier 1 of
the Developing Tier, and is approved for sewer service.
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The vision for the Developing Tier is “to maintain a pattern of low- to
moderate density suburban residential communities, distinct commercial
Centers, and employment areas that are increasingly transit serviceable.”
Land use, environmental, transportation, and public facilities policies
recommended for the Developing Tier are intended “to balance the pace
of development for new communities and businesses with the demands
for adequate roads and public facilities” (MNCPPC 2002a). The 2002
Prince George’s County Approved General Plan anticipates that the
private sector will pay a greater share of the costs for infrastructure. The
Mattawoman property was reclassified from the Rural Tier to the
Developing Tier in the Approved Subregion 6 Master Plan and Proposed
Sectional Map Amendment (MNCPPC 2009) and was placed in Water and
Sewer Category 3 in the December 2010 Cycle of Amendment (MNCPPC
2013).
The closest community to the Mattawoman Site is Brandywine, which is
less than one-half mile from the Project Site. Located within both
Subregion 5 and Subregion 6, Brandywine has attributes of a small town
and contains several historic resources, but is threatened by continued
suburban expansion. A planning study for the revitalization and
preservation of Brandywine was completed in 2011 (MNCPPC 2011). The
Project is within the Brandywine study area and would be accessed from
MD 381 which is a major focus for transportation enhancements in the
plan.
The Mattawoman property that would host the generation facility is
currently vacant. The Site was previously reviewed in 2001 by Prince
George’s County for a recycling facility, but the application was
subsequently withdrawn by the developer. Subsequent to completion of
the Brandywine Revitalization and Preservation Study, the recycling
facility project was opposed by the community because of anticipated
truck traffic on local roads, limited employment potential and less than
optimal use of the Site (MNCPPC 2013). The property is in the I-2 (Heavy
Industrial) Zone. Although Maryland’s CPCN process preempts local
zoning, public utility uses or structures are a permitted use in the I-2 zone.
Mattawoman’s reclaimed water pipeline would be buried under existing
road ROWs for most of its length, where adjacent land uses are primarily
commercial, industrial, and institutional. The natural gas pipeline is
mostly within a railroad ROW and transmission corridor. Private
properties crossed by the pipeline in Charles County are unoccupied and
zoned RC (Rural Conservation). The generator lead line is routed through
lands zoned I-1 (Light Industrial), R-R (Rural Residential) and O-S (Open
Space). One property is protected under a MALPF easement. The
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property chosen for the substation is currently occupied and zoned R-E
(Residential-Estate).
Maryland’s Smart Growth initiative is a set of policies designed to target
development in designated growth areas to protect rural areas. One of the
requirements of the 1997 Smart Growth Act on Maryland’s counties is to
geographically identify Priority Funding Areas (PFA). PFAs provide the
focus for development by targeting State and local resources in areas
where there is public infrastructure to support it. Prince George’s County
PFAs are concentrated in the Developed and Developing tiers, including
one PFA encompassing Brandywine. The Project Site is within the
Brandywine PFA.
Special land uses in the vicinity of the Project include Joint Base Andrews
and the Globecom Receiver Site, an associated installation. Concern about
suburban encroachment upon these facilities prompted the Joint Base
Andrews Naval Air Facility Washington Joint Land Use Study (JLUS) in
2008 (MNCPPC 2009b) which resulted in recommendations for promoting
compatible land use policies around the facility. In 2012, Prince George’s
County implemented an Interim Land Use Code (ILUC) which governs
development in areas impacted by height limitations, high noise levels,
and high accident potential resulting from flight patterns at Joint Base
Andrews for an interim period while long term regulations are being
developed. ILUCs were established to prevent the intensification of
existing land uses while the Military Installation Overlay Zone (MIOZ) is
being developed as proposed in the JLUS and supported by
recommendations in the Air Installation Compatibility Use Zone Study
(AICUZ 2007). Legislation included a zoning bill (CB-3-2012) establishing
boundaries of the ILUC area and controls for uses closest to Joint Base
Andrews, and a subdivision bill (CB-4-2012) to bring development rules
into the subdivision ordinance.
3.6.4
Recreational, Scenic, and Cultural Sites
Located between the Patuxent and Potomac rivers, Prince George’s
County has probably been occupied for at least 10,000 years, as evidenced
by documented Early Archaic sites in Charles and Calvert counties. The
first recorded European visit to Prince George’s County was in 1608 with
the arrival of John Smith on this first voyage of the Chesapeake Bay when
the expedition ascended the Potomac River as far as Great Falls.
Settlement of Prince George’s County followed the founding of Saint
Mary’s City by Lord Calvert through the migration of farms and
plantations along the Patuxent and Potomac rivers. Prince George’s
County was established from parts of Calvert and Charles counties on
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April 23, 1696. Through the 18th and 19th centuries the economy of Prince
George’s County was predominantly agricultural, primarily based on
tobacco cultivation, and began its transformation to a suburban economy
as the 1800’s came to a close with the establishment of satellite towns
along its borders with the District of Columbia. The social and economic
structure of the county was also profoundly influenced by the
Revolutionary War, the War of 1812 and the War Between the States.
Throughout the 20th century to the present Prince George’s County has
further evolved from a suburban outgrowth of the District of Columbia to
a major economic force within the greater Washington metropolitan area.
Many of the cultural resources in southern Prince George’s County reflect
the county’s agricultural heritage including some of the earliest plantation
sites in Brandywine and Aquasco, historic properties overlooking the
Patuxent River and agricultural buildings such as hay and tobacco barns.
These sites overlay numerous pre-historic Native American sites that span
several periods of inhabitation, most near the Patuxent or Potomac rivers.
Known cultural resources near the Mattawoman Site include the historic
communities of T.B. and Brandywine, examples of early crossroads
settlements that developed during the 19th century to service surrounding
populations, and the Gibbons Methodist Church site and cemetery which
thematically relates to the African-American heritage in Prince George’s
County. The closest National Register property, Early Family Historic
District in Brandywine, is about one-half mile from the Mattawoman Site.
Cultural resource preservation in Prince George’s County is guided by the
2010 Approved Historic Sites and Districts Plan (MNCPPC 2010b), an
element of the 2002 General Plan. The plan articulates multiple goals
related to resource protection through designation, preservation planning,
regulation, incentives and partnerships; protection of environmental
settings and cultural landscapes; community revitalization; and heritage
tourism. The Plan places a high priority on protecting historic sites and
their environmental settings, historic resources, cemeteries, archeological
resources, and cultural landscapes from development impacts.
In southern Prince George’s County, partial realization of the Plan is seen
in the Brandywine Revitalization and Preservation Study (MNCPPC 2011)
and the many designated historic and scenic roads in Subregions 5 and 6.
The Brandywine study, for example, seeks to capitalize on its historic
resources and physical setting as a gateway to the Rural Tier to enhance
the community’s overall visual character; improve the streetscape and
roadway conditions, particularly along MD 381 (Brandywine Road); and
revitalize existing business using a historic preservation-based economic
development approach.
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A scenic road is defined in Subtitle 23 of the Prince George’s County Code
as: “a public or private road, as designated by the County Council, which
provides scenic views along a substantial part of its length through
natural or man-made features, such as forest or extensive woodland,
cropland, pasturage, or meadows; distinctive topography including
outcroppings, streambeds and wetlands; traditional building types;
historic sites; or roadway features such as curving, rolling roadway
alignment and leaf tunnels.” A historic road is defined in Subtitle 23 as: “a
public or private road, as designated by the County Council, which has
been documented by historic surveys or maps, and which maintains its
historic alignment and historic landscape context through views of natural
features, historic landscape patterns, historic sites and structures, historic
farmstead groupings, or rural villages” (MNCPPC 2009d).
Guidelines for the treatment of scenic and historic roads in Prince
George’s County have been developed by the Department of Public
Works and Transportation (DPW&T 2006) and a list of all scenic and
historic roads is published in the countywide Master Plan of
Transportation (MNCPPC, 2009d). All development applications
involving scenic and historic roads are reviewed by the Planning
Department’s Environmental Planning Division (MNCPPC 2010b) which
may recommend mitigation through siting of a development or vegetation
buffers. Utility facilities along scenic and historic roadways must also be
designed to have minimal or no impact upon their significant
characteristics. Scenic easements have been established along some scenic
and historic roadways to permanently protect their viewsheds (DPW&T
2007).
The Project has frontage on Brandywine Road, a designated historic road
(MNCPPC 2009). There are no Maryland Scenic Byways in the vicinity of
the Site hosting the generation facility. However, both the reclaimed
water pipeline and natural gas pipeline intersect Booth’s Escape Scenic
Byway.
The Maryland Heritage Areas Program preserves the State’s historical,
cultural, archeological, and natural resources for sustainable economic
development through heritage tourism. This is accomplished through the
local designation and State certification of Heritage Areas, defined by a
distinct focus or theme that makes a place or region different from other
areas of the State. Activities in each Heritage Area are governed by a
management plan that sets forth the strategies, projects, programs,
actions, and partnerships that will be involved in achieving its goals. Once
certified, a Heritage Area management entity becomes eligible for Statematching grants for operating assistance and marketing activities. Local
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jurisdictions and non-profit organizations in a Heritage Area may also
qualify for State matching grants for planning, design interpretation, and
programming. The Maryland Heritage Areas Authority (MHAA), within
the Division of Historical and Cultural Programs of the Maryland
Historical Trust (MHT), is responsible for administering Maryland’s
Heritage Areas program.
There are 13 Certified Heritage Areas (CHAs) in Maryland including the
Anacostia Trails Heritage Area (ATHA) in Prince George’s County. The
ATHA comprises 83.7 square miles and is located in the northern part of
the county. One cluster (Cluster 2) of the Southern Maryland Heritage
Area extends into Prince George’s County from Charles County. The
cluster encompasses the Cedarville State Forest and is traversed by the
Project’s proposed natural gas pipeline.
3.6.5
Public Services and Safety
Prince George’s County’s potable water is a combination of surface water
and groundwater. Surface water is sourced from both the Potomac and
Patuxent rivers and from two storage areas, the Jennings Randolph
Reservoir and Little Seneca Lake, during periods of low flow. The
Washington Suburban Sanitary Commission (WSSC), City of Bowie and
the Beltsville Agricultural Research Center are the major suppliers of
water to Prince George’s County (DER 2008). Community water in
southern Prince George’s County is supplied by the WSSC.
Water and sewer service in Prince George’s County is governed by the
2008 Water and Sewer Plan (DER 2008). Two defining features of the Plan
are the Sewer Envelope and Water & Sewer Categories. The Sewer
Envelope is “a boundary beyond which no community water and sewer
facilities will be approved”. Water & Sewer Categories are the product of
State regulation (COMAR 26.03.01.04) and define the type of water and
sewer service available to a property in the county. Although six
categories are defined in COMAR, Prince George’s County uses only four:
Category 3
Category 4
Category 5
Category 6
Community System
Community System Adequate for Development
Planning
Future Community System
Individual Systems – Well and Septic Systems or
Shared Facilities
In general, public water and sewer service is or will be available to
properties in categories 3, 4 or 5, while properties designated category 6
must use private wells and septic systems. A water category map and
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sewer category map are integral parts of the Plan. Although the Plan
placed the Mattawoman Site in Category 6, the December 2010 Cycle of
Amendment changed both the water and sewer categories of the property
to Category 3 (MNCPPC 2013).
There is a 16-inch water main under Brandywine Road that would service
the Project. The WSSC has identified low pressure sewer issues that will
have to be addressed before the Mattawoman Site can be connected to the
system. Drainage will be to the Mattawoman trunk sewer and wastewater
treatment plant in Charles County, where interceptor capacity has been
determined to be deficient (MNCPPC 2013).
Prince George’s County Police Department is the county’s primary law
enforcement agency, employing more than 1,500 officers. The
Mattawoman Energy Center Project is located in District V which is based
in Clinton. The Maryland State Police serve southern Prince George’s
County (south of US 50) from Barrack L in Forrestville. The Office of the
Sheriff in Upper Marlboro provides additional civil and criminal related
services to the community.
Fire protection and emergency medical services are provided by more
than 1,200 active career and volunteer personnel from 47 fire/rescue
stations. The Site falls within the 35 square mile service area of the
Brandywine Volunteer Fire Department. Currently less than one-quarter
mile from the Site, in June 2012 ground was broken for a new Brandywine
Fire/EMS Station 840 approximately 2.5 miles west of the existing facility.
Emergency management is under the direction of the Office of Emergency
Management (OEM), one of the agencies within the Office of Homeland
Security. OEM coordinates the county’s response during emergencies,
prepares and maintains its Emergency Response Plan, provides
emergency preparedness education to the public and serves as the liaison
to the Maryland Emergency Management Agency.
Prince George’s County is home to five general and medical surgical
hospitals. Southern Maryland Hospital Center in Clinton is the closest
facility, approximately six miles from the Mattawoman Energy Center
Site. Southern Maryland Hospital Center is a 300-bed full-service acute
care and 24-bed sub-acute care facility with a 35-bed emergency center
open 24 hours a day.
Solid waste collection in Prince George’s County is a combination of
county, municipal, and private services. The county does not provide
refuse collection service to commercial or industrial establishments,
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apartments, or other non-county institutional uses. Refuse is currently
hauled to the Brown Station Road Sanitary Landfill, two miles northwest
of Upper Marlboro. The landfill commenced operation in 1968 and now
comprises about 1,450 acres. As permitted, the landfill is expected to
operate to 2020. There are numerous other solid waste facilities such as
recycling centers, rubblefills, special facilities for construction and
demolition waste and yard waste composting, and hazardous materials
located throughout Prince George’s County. Two of these facilities, a
rubblefill and fly ash fill, are located in Brandywine.
Prince George’s County has one of the largest school populations in
Maryland with an enrollment of more than 133,000 full- and part-time
students, a decline of about 13% over the past 10 years. As of September
2011, there were 202 schools in the Prince George’s County public school
system. The FY 2013 Capital Improvement Program request to the State
includes funding for the construction of one new school and three
replacement schools (PGCPS, 2012). Schools in Brandywine are the
nearest public schools to the Site.
3.6.6
Transportation
Several major highways traverse Prince George’s County. The Capital
Beltway (I-95) is a carrier of regional and interregional traffic, and encloses
most of the county’s Developed Tier. US 301 (Crain Highway) is a major
transportation corridor in Southern Maryland and a primary north-south
commuter route from fast-growing suburban communities in Prince
George’s and Charles counties. Near Brandywine, US 301 connects to MD
5 (Branch Avenue), a north-south artery connecting Southern Maryland to
the Capital Beltway. Numerous other major highways serve other parts of
the county. The county’s transit network comprises rail and bus facilities
for Metrorail, MARC, Metrobus, and local (TheBus) services, most of
which are in the Developed Tier, although bus services extend to the
Developing Tier.
Automobile is the primary mobility option in southern Prince George’s
County, with the regional linkages via US 301 and MD 5. MD 381
(Brandywine Road), which accesses the Site, is a roughly west-east
highway linking US 301 and MD 5 to Charles County near the Patuxent
River. The Pope’s Creek Secondary, part of the CSXT rail system, extends
from the Charles County line to a mainline connection in Bowie and
primarily serves the Morgantown Generating Station. At Brandywine, the
CSXT Herbert Secondary connects the Chalk Point Generating Station to
the Pope’s Creek line. There are four general aviation airports in Prince
George’s County, none within five miles of the Mattawoman Energy
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Center Site. There are limited helicopter operations from the adjacent
Globecom Receiver Site.
Traffic experiences severe delays in the US 301 corridor due to high
volumes and inadequate capacities. Furthermore, projected population
and employment growth in Southern Maryland is expected to exacerbate
the problem. In recognition of this, Governor Schaefer and Transportation
Secretary Lighthizer appointed a task force in 1993 to develop
recommendations to address transportation and related problems in the
US 301 corridor from US 50 to the Potomac River Bridge (MDOT, 1996).
Among recommendations addressing land use, jobs, transit and
transportation demand management, the US 301 Transportation Study
task force recommended converting US 301, from the US 301/MD 5 split
at Brandywine to US 50, to a six-lane freeway with service roads by 2020.
Additional recommendations were made for US 301 segments in the
Waldorf and La Plata areas, and south of La Plata to the Potomac River.
Subsequently, National Environmental Policy Act (NEPA) approval for
proposed highway and other transportation improvements was obtained
following the acceptance of Tier I draft and final environmental impacts
statements which recommended the existing US 301 corridor as the
preferred alternative. Tier I approval meant that right-of-way could be
purchased with federal funds for corridor preservation. Rights-of-way
have been acquired since the Record of Decision for the project was
approved in 2001. In the MDOT Consolidated Transportation Program,
the State Highway Administration (SHA) identifies the entire project
(from the Potomac River Bridge to US 50) as the US 301 South Corridor
Transportation Study. Currently, project planning is on hold for the entire
corridor although right-of-way funding is programmed through 2019
(SHA, 2013).
US 301 is the focus of the US 301 Access Management Plan, a collaborative
effort between SHA, Prince George’s County Department of Public Works
and MNCPPC (for the Prince George’s County segment) which is used as
a guide by Prince George’s County and SHA to protect the future US 301
right-of-way from development along the corridor until formal studies are
complete (SHA, undated).
Two transportation projects near the Site are in development, however, to
mitigate severe traffic congestion during peak hours. The MD 5 at MD
373/MD 381 interchange project would relocate Brandywine Road to a
new interchange at MD 5 and MD 373. Engineering and right-of-way
acquisition for this project is currently underway (SHA, 2013). In
addition, SHA is undertaking a study to upgrade MD 5 to a multi-lane
MD PPRP
3-42
freeway from US 301 to the Capital Beltway. This project is in the project
planning phase (SHA, 2013).
On a local scale, the Approved Subregion 6 Master Plan and Proposed
Sectional Map Amendment envisions capacity improvements to
Brandywine Road in the future although such improvements are not in
the county’s Capital Improvement Program (MNCPPC, 2009). The
Brandywine Revitalization and Preservation Study identified several
opportunities along Brandywine Road to improve the existing
infrastructure and manage anticipated increases in traffic volumes
including truck restrictions, traffic calming features, traffic signal warrant
studies at intersections of Brandywine Road with Missouri Avenue and
with Mattawoman Drive, turn lanes, and other improvements (MNCPPC,
2011). A plan for implementing these recommendations has not been
formalized, nor have funding sources been identified.
Before any preliminary plat may be approved in Prince George’s County,
a land developer must show there are adequate access roads available to
serve traffic generated by a proposed subdivision or such roads are
scheduled and funded within the county’s Capital Improvement Program
or within the State’s Consolidated Transportation Program. Criteria for
assessing traffic impacts from land development proposals are
documented in “Guidelines for the Analysis of the Traffic Impact of
Development Proposals” (MNCPPC, 2002b). These guidelines are
currently in the process of being updated (MNCPPC, 2012).
3.7
NOISE
3.7.1
Definition of Noise
Noise generally consists of many frequency constituents of varying
loudness. Three decibels (dB) is approximately the smallest change in
sound intensity that can be detected by the human ear. A tenfold increase
in the intensity of sound is expressed by an additional 10 units on the dB
scale, a 100-fold increase by an additional 20 dB. Because the sensitivity of
the human ear varies according to the frequency of sound, a weighted
noise scale is used to determine impacts of noise on humans. This Aweighted decibel (dBA) scale weights the various components of noise
based on the response of the human ear. For example, the ear perceives
middle frequencies better than low or very high frequencies; therefore,
noise composed predominantly of the middle frequencies is assigned a
higher loudness value on the dBA scale. Subjectively, a tenfold increase in
sound intensity (10 dB increase) is perceived as an approximate doubling
MD PPRP
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of sound. Typical A-weighted sound levels for various noise sources are
shown in Table 3-3.
Table 3-3
Typical Sound Levels for Common Sources (dBA)
Noise Source
Typical Sound
Pressure Level
Lowest sound audible to human ear
10
Soft whisper in a quiet library
30-40
Light traffic, refrigerator motor, gentle breeze
50
Air conditioner at 6 meters, conversation
60
Busy traffic, noisy restaurant, freight train moving 30 mph at 30 meters
70
Subway, heavy city traffic, factory noise
80
Truck traffic, boiler room, lawnmower
90
Chain saw, pneumatic drill
100
Rock concert in front of speakers, sand blasting, thunder clap
120
Gunshot, jet plane
140
Noise monitoring is typically conducted continuously over a period of
time to obtain a representative picture of the acoustic environment. The
length of time required for noise monitoring, and the frequency of
individual measurements, will vary depending upon a number of factors,
including surrounding land use, time of day, the purpose of noise
monitoring, the number of locations at which sound levels are being
measured, and the capabilities of the monitoring equipment being used.
Ambient sound pressure levels can also be expressed in various ways.
Quite often, noise levels are measured or reported as equivalent sound
levels, Leq, over a given time period. A one-hour Leq, for instance, is the
constant sound level that has the same energy content as the actual sound
variations over a one-hour monitoring period. Monitoring of the ambient
noise levels in a community is often reported as Leq as well as L90, the
sound pressure level that is exceeded ninety percent (90%) of the time.
The L90 is also called the “noise floor,” the minimum background noise
level that is characteristic of that monitoring location. The difference
between the L90 and the Leq is an indication of the variability of noise at a
given location.
MD PPRP
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Because sound levels are expressed as relative intensities, multiple sound
sources are not directly additive. Rather, the total noise is primarily a
result of the source of highest intensity. For example, two sources, each
having a noise rating of 50 dBA, will together be heard as 53 dBA; a source
of 65 dBA combined with a source of 85 dBA will result in a noise level of
85.1 dBA. As the intensity difference between the two sources increases,
the effect of the lower sound source becomes negligible.
3.7.2
Existing Noise Levels
The applicant conducted a comprehensive ambient noise survey over a 10day period in January 2013. The survey consisted of a combination of
continuous automatic noise monitoring and a series of manual sampling
where frequency content and valuable observations were made as to the
nature and sources of the measured levels. Measurements were taken at
four locations: Position 1, Brandywine Road; Position 2, Project Site
Entrance Gate; Position 3, Air Force Road; and Position 4, Whistlestop
Road (see Figure 3-8).
MD PPRP
3-45
Figure 3-8
MD PPRP
Noise Monitoring Locations
3-46
Table 3-4 summarizes the average L90 sound levels measured at all four
monitoring positions.
Table 3-4
Average L90 Sound Levels at Mattawoman Site
Position
Average L90 (dBA)
1
39
2
42
3
37
4
40
Hessler Associates conducted the noise analysis for Mattawoman, and the
report was provided in Appendix A-3 to the CPCN application. The
applicant provided the following general conclusions regarding existing
noise conditions at each monitoring location:
•
Position 1 indicated background sound levels that vary with time
of day and traffic volume on Brandywine Road. The L90 level
drops to approximately 30 dBA just after midnight on most nights.
Wind does not significantly affect sound levels, as it normally does
in most rural areas, suggesting that man-made road noise is
essentially dominant at this location.
•
Position 2 sound levels are somewhat similar to those at Position 1,
varying with time and traffic volume. The L90 at Position 2 is
higher, possibly due to more activity of all kinds closer to the center
of Brandywine compounded by truck traffic on the initial portion
of Air Force Road.
•
Position 3 sound levels indicate that this area experiences extended
periods of more or less constant sound interrupted intermittently
by rather loud events, most likely trains or occasional heavy trucks.
•
Position 4 reflects a number of anomaly periods where the sound
level remained relatively elevated in the 55- to 65-dBA range for
extended periods of time. The cause of these high levels is not
known. Outside of these periods, the L90 levels range between 45
and 35 dBA, going as low as 31 dBA on certain nights.
MD PPRP
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4.0
AIR QUALITY IMPACTS
4.1
AIR QUALITY IMPACT ASSESSMENT BACKGROUND AND
METHODOLOGY
4.1.1
Overview
As part of the CPCN application process, PPRP, in conjunction with the
Maryland Department of Environment-Air and Radiation Management
Administration (MDE-ARMA), evaluates potential impacts to air quality
resulting from proposed projects to be licensed in Maryland under Code
of Maryland Regulations (COMAR) 20.80. This evaluation includes
emissions investigations and other studies, including air dispersion
modeling assessments, to ensure that impacts to air quality from proposed
projects are acceptable. PPRP and MDE-ARMA also conduct a complete
air quality regulatory review for two purposes: 1) to assist in the impact
assessment, since air quality regulatory standards and emissions
limitations define levels to protect against adverse health, welfare, and
environmental effects, and 2) to ensure that the proposed project will meet
all applicable regulatory requirements.
PPRP and MDE-ARMA conducted an air quality evaluation of the
proposed Mattawoman Project, to confirm that projected maximum
potential air emissions would meet applicable regulatory thresholds and
limits. The proposed Project was evaluated to determine whether
emissions from the Project would have significant impacts on the existing
ambient air quality in the region. Effects on current ambient air quality
were assessed by performing air dispersion modeling analysis to predict
the future ambient air concentrations resulting from emissions from the
proposed Project.
4.1.2
Regulatory Considerations
EPA defines concentration-based National Ambient Air Quality Standards
(NAAQS) for several pollutants, which are set at levels considered to be
protective of public health and welfare. Specifically, the NAAQS have
been defined for six “criteria” pollutants, including particulate matter
(PM), sulfur dioxide (SO2), carbon monoxide (CO), nitrogen dioxide
(NO2), ozone, and lead (Pb). Two forms of PM (or “total particulates”)
have specific NAAQS: particulate matter less than 10 microns (PM10),
and particulate matter less than 2.5 microns (PM2.5).
MD PPRP
4-1
Air emissions limitations and pollution control requirements are generally
more stringent for sources located in areas that do not currently meet a
NAAQS for a particular pollutant. Areas not meeting a NAAQS for a
pollutant are designated as “nonattainment areas”, areas achieving the
NAAQS are known as “attainment areas”.
Prince George’s County, the location for the Mattawoman Project, is
currently designated as attainment for all pollutants except ozone. EPA
treats the Northeastern United States, from northern Virginia to Maine, as
an ozone nonattainment area known as the Northeast Ozone Transport
Region. Because of the elevated levels of ozone historically measured in
Prince George’s County during the ozone season (May-October), Prince
George’s County has been designated “moderate” ozone nonattainment
area for the 8-hour ozone standard. Emissions of the two pollutants that
contribute to the formation of ozone, volatile organic compounds (VOCs)
and nitrogen oxides (NOx), are regulated more stringently in ozone
nonattainment areas such as Prince George’s County to ensure that air
quality is not further degraded (i.e., the ambient air concentration of
ozone does not continue to increase as new sources of ozone forming
pollutant emissions are constructed). EPA recently changed the air
quality designation of Prince George’s County with respect to PM2.5
NAAQS from nonattainment to attainment. On October 6, 2014, EPA
issued a final rule re-designating the Washington DC area (which includes
Prince George’s County) to attainment for the 1997 annual PM2.5
NAAQS. The EPA final rule became effective on November 5, 2014.
Potential emissions from new and modified sources in nonattainment
areas are evaluated through the nonattainment New Source Review
(NA-NSR) regulatory program. Major new and modified sources in
NA-NSR in Maryland must meet the regulatory requirements of COMAR
26.11.17. The goal of the NA-NSR program is to allow construction of
new emission sources and modifications to existing sources, while
ensuring that progress is made towards meeting, or attaining, the
NAAQS. NA-NSR requires major sources to limit emissions of affected
pollutants through the implementation of the most stringent levels of
pollution control, known as Lowest Achievable Emission Rate (LAER). In
addition, NA-NSR requires pollutant “offsets” to be obtained for every
ton of pollutant emitted at a given ratio (1.3 to 1.0 in Prince George’s
County) as noted in COMAR 26.11.17.03B(3)(a)).
Potential emissions from new and modified sources located in attainment
areas are evaluated through the Prevention of Significant Deterioration
(PSD) program. The goal of the PSD program is to ensure that emissions
from major sources do not degrade air quality in areas where NAAQS are
MD PPRP
4-2
currently being met. Triggering PSD requires use of the Best Available
Control Technology (BACT) and requires affected sources to evaluate
impacts usually through dispersion modeling analysis.
Activities associated with the proposed Project have the potential to emit
the following regulated pollutants: PM, PM10, PM2.5, CO, NOx (nitrogen
monoxide (NO)and nitrogen dioxide (NO2), SO2, sulfuric acid mist (SAM),
lead (Pb), ozone precursors (VOC and NOx), greenhouse gases (GHGs)
expressed as carbon dioxide equivalent (CO2e), and hazardous air
pollutants (HAPs). The potential emissions associated with the Project are
discussed in Section 4.3. The applicability of and compliance with the
major New Source Review regulations is discussed in Section 4.4 for PSD
requirements and Section 4.5 for NA-NSR requirements.
Other federal and state air quality regulations also apply to the Project.
These regulations apply either as a result of the type of emission source
that is to be constructed, or the pollutants to be emitted. These
regulations, discussed in Section 4.6, specify pollutant emission limitations
and specify notification, monitoring, testing, recordkeeping, and reporting
requirements.
4.2
PROPOSED PROJECT SOURCE CHARACTERIZATION
The Mattawoman Project involves the construction of a new combined
cycle combustion facility with a nominal net rated capacity of 990 MW.
The combustion turbines will be fired on natural gas at all times. The air
emission sources to be installed as part of the Project are described below
and summarized in Table 4-4.
4.2.1
Combustion Turbines
The Project will include two Siemens H-class version 1.4 (SGT6-8000H)
combustion turbine (CTs) generators each with a nominal 286 MW
operating capacity (CT1 and CT2). Each CT will include a heat recovery
steam generator (HRSG) equipped with duct burners with a rated
capacity of 687.3 million British thermal units per hour (MMBtu/hr) (DB1
and DB2). The heat in the exhaust gas from the CTs will be recovered in
the HRSGs and heated further using the duct burners to produce steam,
which will be used to run a steam turbine generator (STG) rated at 436
MW (STG1). This 2 x 1 configuration (2 CTs feeding one STG) will be
operated to generate electricity to be supplied to the PJM power grid.
MD PPRP
4-3
The exhaust from the CT/HRSGs would be controlled using a selective
catalytic reduction (SCR) system for NOx and an oxidation catalyst system
for CO and VOC. The NOx emissions will also be controlled using dry
Low NOx (DLN) combustors. The use of pipeline quality natural gas at
≤0.25 grains per 100 standard cubic feet (gr/100 scf) 4 on an annual basis
and ≤1.0 gr/100 scf on a short-term (24 hours or less) basis will limit the
emissions of SO2, PM10, and PM2.5.
4.2.2
Ancillary Units
In addition to the generating units, the Project will include the following
support equipment.
Auxiliary Boiler (AB1)
The Project will include one auxiliary boiler rated at 42 MMBtu/hr fueled
exclusively with natural gas. The boiler will be equipped with low-NOx
burners (LNB) and designed to operate using good combustion practices.
Fuel Gas Heater (FG1)
The Project will include a 13.8-MMBtu/hr natural gas-fired heater to
condition the natural gas prior to combustion in the CTGs. The fuel gas
heater is expected to operate 24 hours/day. 365 days/year (8,760 hours
per year) and will be fueled exclusively on natural gas.
Emergency Engines (EG1 and FWP1)
The Project will include one 1,490-horsepower (hp) diesel-fired emergency
engine intended to provide back-up power to the facility, and a 305 hp
diesel-fired fire water pump engine to be used for emergency purposes.
The emergency engines will combust ultra-low sulfur diesel fuel.
Cooling Tower (CTW1)
One 12-cell, wet, mechanical draft cooling tower will be installed to
remove heat from the water associated with the steam turbine. Reclaimed
water from the Piscataway WWTP will be used as water supply for the
project operations. The reclaimed water will potentially contain some
4 July 2013 CPCN Application
MD PPRP
4-4
total dissolved solids (TDS) which could be emitted from the cooling
tower resulting in PM emissions. The cooling tower will be equipped
with high efficiency drift eliminators with a drift rate of 0.0005% of the
circulating water rate, which is considered state-of-the-art for cooling
towers.
Circuit Breakers (CB1)
Four new 230-kV circuit breakers will be installed as part of this Project.
The circuit breakers will contain sulfur hexafluoride (SF6), which is
considered a greenhouse gas (GHG). The circuit breakers will be sealed
and designed with density alarms to operate with minimal leaks.
Fugitive Pipeline Components (FUG1)
The Project will include various pieces of equipment (i.e., connectors,
valves, flanges, etc.) associated with the on-site portions of the natural gas
pipeline. These equipment components are potential sources of fugitive
leaks of volatile compounds.
Fuel Storage Tanks
The Project also includes the installation and operation of two small diesel
fuel tanks to support the emergency engines. The storage tank capacities
are 2,400 gallons for the emergency generator and 550 gallons for the fire
pump. These will be fixed roof tanks with negligible VOC emissions.
Table 4-1 summarizes the proposed emissions units included as part of the
Mattawoman Project.
MD PPRP
4-5
Table 4-1
Emissions
Units (Number
of Units) (ID #)
Type/Model
Rated Capacity
of Each Unit
Fuel
Maximum Allowable
Operations
Combustion
Turbines (2)
(CTG1 and
CTG2)
Siemens SGT6-8000H
286 MW nominal
Natural gas
8,760 hours per year per
CTG
Duct Burners
/Steam
Generator(2)
(DB1 and DB2)
To be determined prior
to construction
687.3 MMBtu/hr
each (at 59°F)
Natural gas
8,760 hours per year per
duct burner
Auxiliary Boiler
(1) (AB1)
Cleaver Brooks
42 MMBtu/hr
Natural gas
8,760 hours per year
Fuel Gas Heater
(1) (FG1)
to construction
13.8 MMBtu/hr
Natural gas
1,490 hp
Ultra low-sulfur
diesel fuel
Limited to emergency
use and 100 hours per
year for maintenance
and readiness testing
Limited to emergency
use and 100 hours per
year for maintenance
and readiness testing
Emergency
Generator (1)
(EG1)
1
Mattawoman Project Air Emission Sources1
Cummins - DQFAD
Emergency Fire
Water Pump
Engine (1) (FP1)
Clark – JU6H-UFADX8
305 hp
Ultra low-sulfur
diesel fuel
Cooling Tower
(1) (CTW1)
to construction
180,000 gallons
per minute
recirculation rate
-
Circuit Breakers
(CB1)
to construction
Four 230 kV
-
Pipeline
Components
(FUG1)
to construction
-
-
July 2013 Mattawoman CPCN Application and responses to PPRP Data Requests.
Mattawoman provided background information in the CPCN application
on the methods used to calculate potential emissions for the Project. PPRP
independently calculated emissions from the proposed facility, with
results of this analysis summarized in Section 4-3. The State’s evaluation
MD PPRP
4-6
of emissions was based on the recommended hierarchy of emission factors
discussed in EPA’s AP-42 emission factors introduction document 5 as
shown in Figure 4-1. Potential emissions from the Project were estimated
using vendor data, AP-42 emission factors, material balance calculations,
New Source Performance Standards (NSPS) emission standards, and/or
engineering calculations. Detailed backup emissions calculations
performed by PPRP and MDE-ARMA are presented in Appendix B.
PPRP and MDE-ARMA are generally in agreement with the
methodologies adopted by Mattawoman to determine emissions for the
proposed Project. There are some differences in emission estimates, which
are noted in this document.
Figure 4-1
5
Recommended Approach to Estimating Emissions
USEPA, 1995. Introduction to AP-42, Volume I, Fifth Edition. January 1995
MD PPRP
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4.3
PROJECT AIR EMISSIONS
4.3.1
CTs/HRSGs and Duct Burners
Potential emissions for most pollutants emitted by a Siemens H-class CTs
and associated HRSGs and duct burners are based on vendor
specifications provided by Siemens in response to PPRP Data Request No.
15-1. As noted in Mattawoman’s January 2015 Supplemental Filing, the
normal operation of the CTs is expected to consist of both CT/HRSG units
operating at base load with or without supplemental duct burner firing.
As is common with CT/HRSG operations, depending on power demands,
alternate facility operating modes could include evaporative cooling of the
inlet air, duct burner firing, and reduced load for either of the CT/HRSG
units. The CTs are not designed with bypass stacks and will operate only
in combined cycle mode. Furthermore, the CTs/HRSGs are designed to
operate up to 8,760 hours per year and may operate up to a 100 percent
(100%) annual capacity factor.
In the January 2015 Supplemental Filing and subsequent responses to
PPRP Data Requests, Mattawoman provided emission estimates from the
Project for 14 operational cases associated with the CTs and duct burners,
which represent a combination of different ambient temperatures (deg F)
and operational loads (MW). These 14 operational cases include predicted
emissions resulting from operating the CTs at various loads with and
without duct burner firing. Certain operational cases also include the use
of inlet air evaporative cooling.
The concentration based emissions, in ppm, for NOx, CO, and VOC were
based on guarantees provided to Mattawoman by the manufacturer,
Siemens. As presented by Mattawoman, short-term lb/hr and lb/MMBtu
emission rates were based on the ppm emission rate with a ten percent
(10%) margin added to account for flowrate variability and to provide
conservative emission rates for the air quality modeling compliance
demonstration. Hourly (lb/hr) emission rates for NOx, CO, and VOC
were based on the ppm limit for each pollutant without any additional
margin added.
For calculation purposes, PM emissions are assumed equivalent to the
filterable portion of PM only; by definition in Maryland PM10 and PM2.5
include both the filterable and condensable portions of PM 6. The annual
6
COMAR 26.11.01.01
MD PPRP
4-8
PM10 and PM2.5 emission factors were based on specifications provided
to Mattawoman by Siemens in response to PPRP Data Request No. 15-1,
and account for an annual average pipeline natural gas sulfur content of
0.25 gr per 100 scf. PM emissions (filterable emissions) were
conservatively estimated by Mattawoman as fifty percent (50%) of PM10
and PM2.5 emissions (filterable and condensable). Maximum short-term
PM, PM10, and PM2.5 emission factors account for a worst-case shortterm sulfur content of pipeline natural gas of 1.0 gr/100 scf and also
include a ten percent margin to account for stack test variability.
The SO2 short–term and annual emission rates were based on the worstcase short-term sulfur content of natural gas of 1.0 gr/100 scf and the
expected annual average sulfur content of 0.25 gr/100 scf, respectively.
The sulfur content of pipeline quality natural gas, by definition, is 0.5 gr or
less per 100 scf 7.
Sulfuric Acid Mist (SAM) emissions were estimated based on CT/HRSG
inlet natural gas short-term and annual sulfur rates and subsequent sulfur
conversion rates to SAM due to the CT combustion process and control
technologies.
The vendor specification for the CTs/HRSGs did not include emission
rates for GHGs. GHG is defined by EPA to include carbon dioxide (CO2),
methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6),
hydrofluorocarbons (HFCs), chlorofluorocarbons (CFCs),
perfluorocarbons (PFCs), and other fluorinated greenhouse gases 8. For
the CTs/HRSGs, the total GHG emissions are calculated as the sum of
CO2, CH4, and N2O, expressed as carbon dioxide equivalent (CO2e). Each
GHG pollutant has varying potential to contribute to global warming,
which is expressed in terms of a global warming potential (GWP). The
GWP potential for CO2 is 1, CH4 is 25, and N2O is 298. Mattawoman
calculated future projected GHG emissions from the CTs/HRSGs using
emission factors from EPA’s Mandatory GHG Reporting Rule for
combustion sources codified at 40 CFR Part 98 Subpart C (CH4 and NO2)
and 40 CFR Part 75 Appendix G (CO2). The heat inputs for the CTs and
HRSGs provided on the vendor specification sheets, along with the
emission factors were used to calculate short-term (lb/hr) and annual
emissions (tpy). A 9.5% degradation factor was applied to all CO2, CH4,
N2O, and CO2e emissions calculations to account for design margin,
turbine degradation between maintenance overhauls, measurement
7
40 CFR §72.2
8
USEPA, 2010. 40 CFR Part 98, 74 FR 16621
MD PPRP
4-9
uncertainty, and variations in the fuel gas quality. The design margin was
developed based on:
•
Design margin of 3.3% to reflect equipment as actually constructed
and installed.
•
Performance degradation of 6% to reflect reduced efficiency from
normal wear and tear of equipment between major maintenance
overhauls.
As previously mentioned, Siemens provided data for 14 normal
operational cases. Short-term emissions for the CTs/HRSGs were
calculated for each of the different operational cases to determine the
worst-case short-term emission rate for each pollutant at any normal
operational case. The maximum short-term emission rates with and
without DBs are provided in Table 4-2 in both lb/hr and lb/MMBtu, with
the operational cases that each emission rate represents. Due to the
variability of total heat input from the CTs/HRSGs across the 14 different
cases (1,448 MMBtu/hr to 3,637 MMBtu/hr) the worst case lb/hr and
lb/MMBtu emission rates may result from different operational cases for
each pollutant.
MD PPRP
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Table 4-2
Pollutant
NOx
CO
VOC
SO2
PM10/
PM2.5
PM
(filterable)
GHG
(CO2e)
Maximum Short-Term Emission Rates for Normal
Operation – For One CT/HRSG
Duct
Burner
(DB) Firing
Maximum
Short-term
Emissions
(lb/hr)
Maximum
Short-term
lb/hr
Emission
Rate Case
Maximum
Short-term
Emissions
(lb/MMBtu)
Maximum
Short-term
lb/MMBtu
Emission
Rate Case
With DB
30.14
MEC-2
0.00829
MEC-2
Without DB
24.86
MEC-1
0.00833
MEC-11
With DB
18.37
MEC-2
0.00505
MEC-2
Without DB
15.18
MEC-1
0.00509
With DB
10.01
MEC-2
0.00275
MEC-10
MEC-12
Without DB
4.40
MEC-1
0.00148
MEC-11
With DB
9.91
MEC-2
0.00273
All Cases
Without DB
8.15
MEC-1
0.00273
All Cases
With DB
27.7
MEC-2
0.00784
MEC-12
Without DB
17.9
MEC-1
0.00790
MEC-9
With DB
13.9
MEC-2
0.00392
MEC-12
Without DB
8.9
MEC-1
0.00395
MEC-9
With DB
473,394
MEC-2
Without DB
388,911
MEC-1
130.17
All Cases
In addition to normal operation of the CTs/HRSGs, Mattawoman
calculated emissions associated with startup and shutdown periods for
the CTs/HRSGs. Three separate startups are defined for these Siemens
combined cycle combustion turbines. For each of the three types of
startups, the duration of the startup event is the expected time necessary
for the HRSG, SCR, and oxidation catalyst to reach the necessary
temperatures for compliance with all normal operation emission limits.
The various startup scenarios are defined below, with durations of each
scenario noted.
•
Cold startup – a CT has been down for at least 64 hours after a
shutdown or when the steam turbine rotor temperature is less than
or equal to 485 °F. A cold startup is expected to take up to 49
minutes.
•
Warm startup – a CT has been idle for less than 64 hours and
greater than 16 hours or when the steam turbine rotor temperature
is between 485 °F and 675 °F. A warm startup is expected to take
up to 51 minutes.
MD PPRP
4-11
Hot startup – a CT has been idle for less than 16 hours after a
shutdown or when the steam turbine rotor temperature is greater
than 675 °F. A hot startup is expected to take up to 46 minutes.
•
The numbers of projected startup and shutdown events for the Project
CTs for a given year are summarized in Table 4-3 from information
provided by Mattawoman in the January 2015 Supplemental Filing.
Table 4-3
Type
Startup
Shutdown
Projected Number of Annual Startup and Shutdown Events
Sub-Type
Duration
(min/event)
No. Events
per Year
Total Hours/
year
Cold
Warm
Hot
-
49
51
46
13
10
50
250
310
8.2
42.5
191.7
67.2
Emission factors associated with startup and shutdown events from the
CT vendor were used to calculate emissions. Future projected annual
emissions (in tons per year) associated with startup and shutdown events
for one CT/HRSG are summarized in Table 4-4.
Table 4-4
Projected Annual Emissions During Startup and Shutdown
Periods For One CT/HRSG
Pollutants
Cold
Startup
Emissions
(tpy)
Warm
Startup
Emissions
(tpy)
Hot
Startup
Emissions
(tpy)
Shutdown
Emissions
(tpy)
Total Startup and
Shutdown Annual
Emissions (tpy)
NOx
0.8
3.3
13.1
3.6
20.8
CO
8.9
36.5
152.0
24.2
221.6
VOC
1.5
6.5
25.9
9.8
43.6
SO2
0.01
0.08
0.39
0.11
0.6
PM10/PM2.5
0.05
0.27
1.24
0.39
1.9
PM (filterable)
0.02
0.14
0.63
0.20
1.0
CO2
585
3,666
16,848
4,823
25,921
CH4
0.01
0.07
0.31
0.09
0.48
N2O
0.00
0.01
0.03
0.01
0.05
CO2e
585
3,669
16,865
4,828
25,947
The maximum annual (tons per year) emissions from the CT/HRSGs were
calculated as the worst case of the 14 normal operating scenarios plus
three startup/shutdown scenarios. In addition to the normal operations
MD PPRP
4-12
associated with the CTs/HRSGs, the potential emissions associated with
startup and shutdown conditions were included. As discussed above, a
cold startup assumes 64 hours of downtime prior to the startup event
beginning and a warm startup assumes 16 hours of downtime prior to the
startup event beginning. Based on these estimates of downtime, and the
number of startup events in a year, Mattawoman estimated that the
CTs/HRSGs will have downtime of approximately 1,689.5 hours per year
associated with 10 cold startups, 50 warm startups, and 250 hot startups.
The following three annual operating scenarios were considered to
determine the worst case annual emissions from the Project:
•
Scenario 1 - CTs operating for 8,760 hours per year without startup
and shutdown events or duct firing;
•
Scenario 2 - CTs operating for 2,760 hours per year without duct
firing, CTs operating for 6,000 hours per year with duct firing, and
no startup and shutdown events;
•
Scenario 3 - CTs operating for 761 hours per year without duct
firing, CTs operating for 6,000 hours per year with duct firing,
1,689.5 hours per year of downtime, and 309.5 hours per year of
startup and shutdown events.
For all three scenarios, emissions were calculated using emission factors
from operational cases MEC-6 (without duct firing) and MEC-7 (with duct
firing), which represent the CT/HRSG operating at 100 percent (100%)
load at 59ºF. The worst-case emissions on a pollutant-by-pollutant basis
from any scenario were then determined and used to estimate worstcase
annual emissions. A summary of the maximum annual emissions from
the two CT/HRSGs is presented in Table 4-5. The annual emissions from
the CT/HRSGs associated with each scenario are presented in Appendix
A.
MD PPRP
4-13
Table 4-5
Maximum Annual Emissions from Two CT/HRSGs
Combined
Maximum
Annual
Emissions for
Two CT/HRSGs
Combined (tpy)
Estimation
Methodology
Basis for Annual WorstCase Emissions
(Operating Scenario)
NOX
213.6
Vendor specifications
Scenario 2: CTs: 2760 hours
CTs/HRSGs: 6,000 hours
CO
547.7
SU/SD events: 309.5 hours
VOC
141.6
SO2
19.4
Sulfur content and
engineering
calculations
SU/SD events: 309.5 hours
144.8
72.4
SAM
10.9
Sulfur content and
engineering
calculations
CO2
3,705,409
CH4
68.6
N2O
6.9
40 CFR 98
Subpart C
GHG(CO2e)
3,709,170
Regulated
Pollutant
PM10/
PM2.5
PM
(filterable)
Notes: SU = Startup; SD = Shutdown
In addition to criteria pollutants and GHGs, Mattawoman presented
estimated HAP emissions for the Project. There were no vendor provided
emission factors available for HAPs for the CT/HRSGs; therefore,
Mattawoman used emission factors from EPA’s AP-42 Section 3.1 for
Stationary Gas Turbines to reflect normal operation associated with the
CTs for all HAPs with the exception of formaldehyde and lead.
Formaldehyde emissions from normal operation of the CTs were based on
the 95th upper percentile formaldehyde emission factor for lean premix
CTGs from EPA’s August 21, 2001 memorandum (Roy, Sims). Lead
emissions from normal operations of the CTs were conservatively based
on EPA’s AP-42 Section 1.4 lead emission factor for Natural Gas
Combustion.
MD PPRP
4-14
Mattawoman did not provide separate HAP emissions calculations
associated with the operation of the duct burner. Therefore, PPRP
calculated HAP emissions from normal operation of the duct burner based
on EPA’s AP-42 Section 1.4 for Natural Gas Combustion, with the
exception of hexane. Hexane emissions from normal operation of the duct
burner were calculated on a mass balance approach based on the natural
gas composition provided by Siemens in response to PPRP Data Request
15-1.
The worstcase HAP emission rates on a pollutant-by-pollutant basis were
determined by multiplying the lb/MMBtu HAP emission factors for
normal operation of the CTs and duct burners by the heat inputs for
normal operating cases with the highest heat inputs. A summary of the
HAP lb/MMBtu emission factors and the worstcase lb/hr emission rates
from one CT and one duct burner during normal operation is included in
Table 4-6.
MD PPRP
4-15
Table 4-6
Projected HAP Short-Term Emissions from Normal
Operation of One CT/HRSG
HAP
1,3-Butadiene
Acetaldehyde
Acrolein
Benzene
Dichlorobenzene
Ethylbenzene
Formaldehyde
Hexane
Naphthalene
POM
Propylene Oxide
Toluene
Xylene
HAP Metals
CT
Emission
Factor
(lb/MMBtu)
4.3E-07
4.0E-05
6.4E-06
1.2E-05
NA
3.2E-05
2.0E-04
NA
1.3E-06
2.2E-06
2.9E-05
1.3E-04
6.4E-05
4.9E-07
DB Emission
Factor
(lb/MMBtu)
NA
NA
NA
2.1E-06
1.2E-06
NA
7.4E-05
1.1E-05
6.0E-07
8.6E-08
NA
3.3E-06
NA
5.4E-06
Maximum
Emission Rate for
One CT + One DB
(lb/hr)
1.29E-03
1.20E-01
1.91E-02
3.72E-02
8.09E-04
9.56E-02
6.51E-01
7.46E-03
4.27E-03
6.63E-03
8.67E-02
3.91E-01
1.91E-01
5.03E-03
Mattawoman assumed that the HAP emission factors for normal
operation were representative of HAP emissions during startup and
shutdown in their January 2015 Supplemental Filing. However, based on
the information provided by Siemens for other pollutants such as CO and
VOC, there can be a significant increase in emission rates during startup
and shutdown events.
Typically, CTs/HRSG vendors do not provide estimates of HAP
emissions during startup and shutdown conditions. Therefore, the use of
a surrogate, or empirical data, is commonly used to derive estimates of
HAP emissions during these events. Based on an understanding of
combustion processes, the CO and VOC emissions generated during
combustion change linearly; in other words, CO and VOC emissions
increase and decrease together. The use of CO as a surrogate to determine
the trend in VOC emissions is considered appropriate. Since many of the
HAP pollutants generated during the combustion process are also
considered VOCs, HAPs are generally considered a subset of VOC.
Therefore, CO will alos be used as a surrogate for HAPs. The ratio of CO
to HAPs during normal operation and uncontrolled CO emissions
estimated during startup and shutdown conditions were used to calculate
HAP emissions during these events.
Annual worst case HAP lb/hr CT/HRSG emission rates were also
calculated on a pollutant-by-pollutant basis from any of the different 14
MD PPRP
4-16
operating cases, and assuming 8,760 hours of operation per year. The
HAP emission calculations for startup and shutdown events are included
in the Scenario 3 emission totals. The results of these annual HAP
emissions calculations are presented in Table 4-7.
Table 4-7
Summary of Annual HAP Emissions – Two CT/HRSGs
Combined
HAPs
1,3-Butadiene
Acetaldehyde
Acrolein
Benzene
Dichlorobenzene
Ethylbenzene
Formaldehyde
Hexane
Naphthalene
POM
Propylene Oxide
Toluene
Xylene
HAP Metals
Total HAPs
4.3.2
Using Maximum
lb/hr rates at
8760 hrs/yr
(tpy)
Annual
Scenario 1
(tpy)
Annual
Scenario 2
(tpy)
0.01
1.05
0.17
0.33
0.01
0.84
5.71
0.07
0.04
0.06
0.76
3.42
1.68
0.04
0.01
0.98
0.16
0.29
NA
0.78
4.94
NA
0.03
0.05
0.71
3.18
1.56
0.01
0.01
0.98
0.16
0.30
0.005
0.78
5.24
0.04
0.03
0.05
0.71
3.19
1.56
0.03
Annual
Scenario 3
(includes
SU/SD)
(tpy)
0.01
0.97
0.16
0.30
0.005
0.78
5.20
0.06
0.03
0.05
0.70
3.17
1.55
0.03
14.17
12.70
13.10
13.02
Auxiliary Boiler
The auxiliary boiler will be used to provide steam during periods of CT
startup. At the time of the January 2015 Supplemental Filing,
Mattawoman had not identified a specific vendor for the auxiliary boiler.
The emissions associated with the auxiliary boiler were either based on
regulatory requirements, such as BACT or LAER, which are discussed
elsewhere in this report, or on EPA’s AP-42 emission factors.
The emissions of NOx, CO, and VOC were based on applicable BACT or
LAER limits. Emissions of PM, PM10, PM2.5, and lead were based on AP42 emission factors. Mattawoman conservatively assumed that PM10 and
PM2.5 emissions, including both filterable and condensable particulate,
would be equal. SO2 short–term and annual emissions were based on the
worst-case short-term sulfur content of natural gas of 1.0 gr/100 scf and
the expected annual average sulfur content of 0.25 gr/100 scf. SAM
MD PPRP
4-17
emissions from the auxiliary boiler were calculated based on the SO2
emission rate and the molecular weight of SO2 and SO3. Emissions of
GHGs were based on EPA’s GHG Reporting Rule (40 CFR Part 98 Subpart
C, Tables C-1 and C-2). In addition, AP-42 factors were used to estimate
emissions of HAPs from the auxiliary boiler, with the exception of hexane,
which was calculated based on mass balance using the natural gas
composition and AP-42 VOC emission factor.
Potential emissions from the auxiliary boiler were calculated based on
8,760 hours of total operation per year and assumed a natural gas heat
content of 1,048 Btu/scf (Table B-20 of the January 2015 Supplemental
Filing). A summary of potential short-term and annual emissions from
the auxiliary boiler is presented in Table 4-8.
Table 4-8
Potential Emissions from the Auxiliary Boiler
Pollutant
NOX
CO
VOC
PM10/PM2.5
PM
(filterable)
SO2
SAM
Lead
CO2
CH4
N2O
GHG (CO2e)
HAPs
4.3.3
Short Term
Emissions
(lb/hr)
Annual
Emissions
(tpy)
0.42
1.55
0.13
0.31
1.84
6.81
0.55
1.37
0.078
0.34
0.11
0.18
2.06E-05
4,914
0.09
0.01
4,919
3.97E-03
0.13
0.19
9.02E-05
21,523
0.41
0.04
21,545
1.74E-02
Fuel Gas Heater
The fuel gas heater will be used to heat natural gas fuel lines and prevent
them from freezing. At the time of the January 2015 Supplemental Filing,
Mattawoman had not identified a specific vendor for the fuel gas heater.
The emissions associated with the fuel gas heater were based on
regulatory requirements, such as BACT or LAER, or on EPA’s AP-42
emission factors.
The emissions of NOx, CO, and VOC were based on applicable BACT or
LAER limits. Emissions of PM, PM10, PM2.5, and lead were based on AP42 emission factors. Mattawoman conservatively assumed that PM10 and
MD PPRP
4-18
PM2.5 emissions, including both filterable and condensable particulate,
will be equal. SO2 short–term and annual emissions were based on the
worst-case short-term sulfur content of natural gas of 1.0 gr/100 scf and
the expected annual average sulfur content of 0.25 gr/100 scf. SAM
emissions from the fuel gas heater were calculated based on the SO2
emission rate and the molecular weight of SO2 and SO3. Emissions of
GHGs were based on EPA’s GHG Reporting Rule (40 CFR Part 98 Subpart
C, Tables C-1 and C-2). In addition, AP-42 factors were used to estimate
emissions of HAPs from the fuel gas heater, with the exception of hexane,
which was calculated based on mass balance using the natural gas
composition and AP-42 VOC emission factor.
Fuel gas heater emissions assume that the unit could operate for the entire
year (8,760 hr/yr) and assume a 1,048 Btu/scf natural gas heat content per
Table B-20 of the January 2015 Supplemental Filing. A summary of
potential short-term and annual emissions from the fuel gas heater is
presented in Table 4-9.
Table 4-9
Potential Emissions from the Fuel Gas Heater
Pollutant
NOX
CO
VOC
PM10/PM2.5
PM (filterable)
SO2
SAM
Lead
CO2
CH4
N2O
GHG (CO2e)
HAPs
4.3.4
Short Term
Emissions
(lb/hr)
Annual
Emissions
(tpy)
0.48
0.29
0.07
0.10
0.026
0.038
0.06
6.76E-06
1,615
0.03
0.003
1,616
1.30E-03
2.12
1.27
0.33
0.45
0.11
0.04
0.06
2.96E-05
7,072
0.13
0.01
7,079
5.71-03
Emergency Generator and Fire Water Pump
Both engines proposed as part of the Project, one emergency generator
and one emergency fire water pump, will be diesel-fired and will operate
only for testing purposes and in the event of an emergency. The
emergency generator is rated at 1,490 hp and the fire water pump is rated
at 305 hp. Both engines are considered compression ignition (CI)
reciprocating internal combustion engines (RICE) and are subject to the
MD PPRP
4-19
New Source Performance Standard (NSPS) for RICE codified at 40 CFR
Part 60 Subpart IIII.
NSPS Subpart IIII specifies emission limits for non-methane hydrocarbon
(NMHC)+NOX, CO, and PM depending on the size and the model year of
the engine. Total hydrocarbons are made up of methane (which typically
form the majority of the hydrocarbons) and non-methane hydrocarbons,
which are typically considered equivalent to VOC. NOx emissions were
conservatively assumed equal to 70% of the combined (NMHC+NOx)
emission limit and VOC was assumed to be the remaining 30% of the
emissions limit. It should be noted that the NSPS limit for PM is based on
filterable emissions only. The condensable emissions portion of PM10 and
PM2.5 was conservatively calculated using EPA’s AP-42 Section 3.4-1
condensable particulate emission factor for large uncontrolled stationary
diesel engines. The sulfur content of the fuel and hourly rated fuel
throughputs were used to calculate the SO2 emissions from the engines.
SAM emissions from the engines were calculated based on their SO2
emission rate and the molecular weight of SO2 and SO3.
HAP emissions from the engines were calculated using EPA’s AP-42
emission factors (Section 3.4 for engines greater than 600 hp, and Section
3.3 for the fire water pump engine). GHG emissions from the engines
were calculated using emission factors in EPA’s GHG Reporting Rule (40
CFR Part 98 Subpart C).
Both the emergency generator and fire water pump emissions assume a
maximum annual operation of 500 hours per year for testing and
emergency use. A summary of potential short term and annual emissions
from the emergency generator and fire water pump is presented in Table
4-10.
MD PPRP
4-20
Table 4-10
Potential Emissions from the Emergency Generator and the
Fire Water Pump
Pollutant
NOX
CO
VOC
SO2
SAM
PM10, PM2.5
PM
GHG (CO2e)
HAPs
4.3.5
1,490 hp Emergency
Generator
Short Term
Annual
Emissions
Emissions
(lb/hr)
(tpy)
11.2
2.8
8.5
2.1
4.6
1.15
305 hp Fire Water Pump
Short Term
Annual
Emissions
Emissions
(lb/hr)
(tpy)
1.41
0.35
1.75
0.44
0.61
0.15
0.015
0.004
0.0031
0.0008
0.024
0.570
0.493
1,636.4
1.70E-02
0.006
0.142
0.123
409.1
4.26E-03
0.0047
0.12
0.10
327.3
7.92E-03
0.0012
0.029
0.025
81.8
1.98E-03
Cooling Tower
The Project will involve the operation of a 12-cell mechanical draft cooling
tower to cool the exhaust water before discharge. The source of cooling
water will be the Piscataway WWTP Operation of the cooling tower will
result in PM, PM10 and PM2.5 emissions. Particulate emissions from
cooling towers are influenced by the water circulation rate, TDS content of
the circulating cooling water, and the efficiency of the drift elimination
system.
For the proposed Project, the cooling tower will have a water circulation
rate of 180,000 gallons per minute (gpm) and will be equipped with drift
elimination systems designed to achieve a drift loss rate of less than or
equal to 0.0005 percent (0.0005%). Mattawoman reviewed historic water
sampling data to determine the TDS content of the cooling water, and
used a TDS of 5,000 parts per million (ppm) as the average measured
value.
To estimate emissions of fine particulate matter (PM10 and PM2.5)
fractions of PM, Mattawoman applied the Reisman/Frisbie methodology,
calculated to be 30% for PM10 and 0.2% for PM2.5 (Reisman). A summary
of potential emission estimates for the cooling tower is presented in Table
4-11.
MD PPRP
4-21
Table 4-11
Potential Emissions from the Cooling Tower
Hourly (lb/hr)
Daily (lb/day)
Annual (tpy)
1
2
4.3.6
PM1
2.3
54.1
9.9
PM102
0.67
16.2
3.0
PM2.52
0.004
0.104
0.019
PM calculated based on flow rate, drift rate, and total dissolved solids.
Reisman, J. and Frisbie, G., “Calculating Realistic PM10 Emissions From Cooling Towers.”
Circuit Breakers
As a part of the Project, Mattawoman proposes to install circuit breakers
that contain a GHG, sulfur hexafluoride (SF6). Mattawoman proposes to
install four, 230-kV circuit breakers. There is a potential for minor leaks of
SF6 from circuit breakers resulting in SF6 emissions to the atmosphere.
The volume of any such emissions is expected to be small; however, given
the high GWP for SF6 which is 22,800, even small emissions of SF6
emissions can result in increased levels of GHG emissions on a CO2e basis.
Potential SF6 emissions from the circuit breakers were calculated based on
a leak rate of a 0.5% of total SF6 charge in the circuit breakers, which
equates to a potential GHG emission rate from the circuit breakers of 45.6
tpy CO2e. A leak rate of a 0.5% is based on other similar sized circuit
breakers approved in prior permits issued around the country in the last
few years and is considered conservative for this type of source.
4.3.7
Natural Gas Component Fugitive Emissions
The proposed Project will involve certain equipment related to natural gas
pipelines, including components such as valves, flanges, relief valves,
compressors, and sampling lines. Operation of the pipeline has the
potential for fugitive releases of natural gas, and components of natural
gas, including VOC, CO2, methane, and hexane from these types of
components. Fugitive emissions from pipeline components are
minimized by routine and frequent inspection of the lines to detect leaks
to enable timely repair of the leaks.
Emissions of CO2 and methane associated with fugitive leaks from system
components were calculated using component counts and emission
factors based on EPA’s Mandatory Reporting Rule, 40 CFR 98, Table
W-1A. Emissions of VOC and hexane were calculated using component
counts, gas composition, and emission factors from Table 2-4 of EPA’s
Protocol for Equipment Leak Emission Estimates (EPA Emissions). A
MD PPRP
4-22
summary of potential emissions associated with fugitive components is
Table 4-12
4.3.8
Potential Fugitive Emissions from Natural Gas Components
Component
Type
Component
Count
CO2
(tpy)
CH4
(tpy)
CO2e
(tpy)
VOC
(tpy)
Hexane
(tpy)
Valves
234
0.075
1.019
25.56
0.24
0.010
Flanges
Relief
Valves
370
0.013
0.179
4.49
0.03
0.001
19
0.009
0.123
3.07
0.04
0.002
Total
623
0.097
1.321
33.12
0.32
0.013
Ammonia Emissions
Ammonia is not a federally or State of Maryland regulated air pollutant;
however, ammonia reacts with nitric acid and sulfuric acid in the
atmosphere to form fine particulate matter. For this Project, Mattawoman
proposes to use aqueous ammonia as a reagent in the SCR system. The
catalyst bed provides active sites where, as the gases pass through the
bed, ammonia reacts with NOx in the exhaust stream. SCR systems utilize
ammonia reagents efficiently, as evidenced by the fact that only one mole
of ammonia is required to reduce one mole of NOx for a properly
designed unit. Unreacted ammonia that passes through the catalyst and is
emitted to the atmosphere is known as “ammonia slip.” The proposed
SCR system will be limited to an ammonia slip of 5 ppm. Given the
expected operation of the CTs and the SCR, emissions associated with the
ammonia slip are calculated to be 198 tpy.
4.3.9
HAP Emissions
Table 4-13 presents an estimate of the total HAP emissions from all
proposed Project sources. A facility is considered a “major” source of
HAPs if the potential to emit is 10 tpy or more of any individual HAP, or
25 tpy or more of all HAPs combined. As presented in Table 4-13,
maximum total HAPs from the proposed Project are estimated to be less
than 25 tpy and all individual HAPs are estimated to be less than 10 tpy;
therefore, the facility is not considered a major source of HAPs.
MD PPRP
4-23
Table 4-13
4.3.10
Total Potential HAP Emissions from All Proposed Project
Sources
HAP Pollutant
Facility Total
(tpy)
1,3-Butadiene
Acetaldehyde
Acrolein
Benzene
Dichlorobenzene
Ethylbenzene
Formaldehyde
Hexane
Naphthalene
POM
Propylene Oxide
Toluene
Xylenes
HAP Metals
0.01
1.05
0.17
0.33
0.01
0.84
5.72
0.08
0.04
0.06
0.76
3.42
1.68
0.05
Total HAPs
14.21
Max Individual HAP
5.72
Summary of Project Emissions
Summaries of short-term (lb/hr) and annual emissions (tpy) associated
with all proposed Project sources are presented in Tables 4-14 and 4-15..
Small variations in emissions were noted between the January 2015
Supplemental Filing and PPRP Data Request responses, and those
estimated by PPRP and MDE-ARMA. However, the differences in
emission estimates are generally within rounding tolerances with two
exceptions.
Mattawoman provided estimates of SAM emissions for the CT/HRSGs,
but did not provide estimates of SAM from for any of the other
combustion sources. PPRP and MDE-ARMA’s calculations include
estimates of SAM emissions for the auxiliary boiler, fuel gas heater,
emergency generator and fire water pump.
The second exception relates to the annual emissions of PM, PM10, PM2.5,
NOx, CO, and VOC from the CT/HRSGs. Mattawoman included a 10%
margin in their annual emissions calculations of these pollutants from the
CT/HRSGs. PPRP’s calculations do not include this 10% margin in the
annual emissions. While a margin to account for variability in short-term
MD PPRP
4-24
emissions may be justifiable due to uncertainty related to stack tests and
vendor emission estimates, PPRP and MDE-ARMA believe that the
application of a margin on an annual basis is inappropriate, and would
result in an annual emissions profile that is exaggerated and not
representative of potential to emit. Any short-term variability in
emissions cannot be expected to apply to every hour of operation for the
entire year. Therefore, the annual emissions from the CT/HRSGs
calculated by PPRP and MDE-ARMA reflect vendor estimates and do not
include an additional margin.
MD PPRP
4-25
Table 4-14
Unit
CT/HRSG
(each)
Without DB
CT/HRSG
(each)
With DB
Summary of Short-Term Emissions from the Project
Units of
Mearure
NOX
VOC
CO
PM
PM10/ PM2.5
SOX
Lead
Sulfuric
Acid Mist
CO2e
2.0
1.0
2.0
-
-
-
-
-
-
24.9
4.4
15.2
8.9
17.9
8.1
1.46E-03
4.6
388,911
lb/MMBtu
ppm @15%
O2
lb/hr
0.0083
0.0015
0.0051
0.0040
0.0079
0.0027
4.90E-07
0.0015
130.17
2.0
1.9
2.0
-
-
-
-
-
-
30.1
10.0
18.4
13.9
27.7
9.9
1.78E-03
5.6
473,394
ppm @15%
O2
lb/hr
lb/MMBtu
0.0083
0.0028
0.0050
0.0039
0.0078
0.0027
4.90E-07
0.0015
130.17
Auxiliary
Boiler
lb/MMBtu
0.010
0.003
0.037
0.0019
0.0075
0.0027
4.9E-07
4.2E-03
117.1
lb/hr
0.42
0.13
1.55
0.08
0.31
0.11
2.1E-05
0.18
4,919
Fuel Gas
Heater
lb/MMBtu
0.0350
0.0054
0.021
0.0019
0.0075
0.0027
4.9E-07
4.2E-03
117.1
1,490 hp
Generator
305 hp Fire
Water Pump
Cooling
Tower
Circuit
Breakers
Natural Gas
Components
Fugitives
MD PPRP
lb/hr
0.48
0.07
0.29
0.03
0.10
0.04
6.8E-06
0.06
1,616
g/bhp-hr
3.4
1.4
2.6
0.15
0.17
0.0047
-
0.0071
-
lb/MMBtu
-
-
-
-
-
-
-
-
163.6
lb/hr
11.2
4.6
8.5
0.5
0.6
0.02
-
0.0235
1,636
g/bhp-hr
2.1
0.9
2.6
0.15
0.17
0.0046
-
0.0071
-
lb/MMBtu
-
-
-
-
-
-
-
-
163.6
lb/hr
1.4
0.6
1.7
0.1
0.003
-
0.0047
327.3
lb/hr
-
-
-
2.3
0.1
0.67 (PM10)
0.0043 (PM2.5)
-
-
-
-
lb/hr
-
-
-
-
-
-
-
-
10.4
lb/hr
-
0.07
-
-
-
-
-
-
7.56
4-26
Table 4-15
Summary of Annual Emissions from the Project (tpy)
NOX
VOC
CO
PM
PM10
PM2.5
SO2
Pb
SAM
CO2e
2 CTs/HRSGs
213.6
141.6
547.7
72.4
144.8
144.8
19.4
0.01
10.9
3,709,170
Auxiliary Boiler
1.84
0.55
6.81
0.34
1.37
1.37
0.13
9.0E-5
0.19
21,545
Fuel Gas Heater
2.12
0.33
1.27
0.11
0.45
0.45
0.04
3.0E-5
0.06
7,079
Emergency Generator
2.79
1.15
2.13
0.12
0.14
0.14
0.004
-
0.006
409.1
Fire Water Pump
0.35
0.15
0.44
0.03
0.03
0.03
0.001
-
0.001
81.8
Cooling Tower
-
-
-
9.87
2.96
0.02
-
-
-
-
Circuit Breakers
Natural Gas
Components Fugitives
-
-
-
-
-
-
-
-
-
45.6
-
0.32
-
-
-
-
-
-
-
33.1
220.7
144.1
558.4
82.9
149.8
146.8
19.6
0.014
11.2
3,738,364
242.1
149.5
568.8
90.1
164.2
161.3
19.6
0.014
11.0
3,738,498
Facility Total
Mattawoman
Estimated Facility
Total Emissions1
MD PPRP
4-27
4.3.11
Construction Emissions
In the July 2013 CPCN Application, Mattawoman stated that construction
activities for the Project would generate emissions from several activities:
land clearing, site preparation, earth moving and material handling,
vehicle movement on unpaved roads, and use of fossil fuel-fired
construction equipment and vehicles. The January 2015 Supplement
Filing did not change any of the estimates related to construction
emissions.
Site preparation activities, including excavation, fill, grading, and vehicle
use on unpaved roads, may generate particulate matter (PM, PM10, and
PM2.5) emissions for the duration of the construction activities, which is
estimated to last over a three-year period. To minimize the effects of this
fugitive dust, Mattawoman intends to utilize appropriate dust
suppression control methods, as necessary.
Other sources of emissions during construction result from the
combustion of fuel in construction equipment and vehicles. Construction
equipment and vehicle engines combust fuel that generate emissions of
NOx, CO, SO2, VOCs, HAPs, and particulates. To minimize pollutant
emissions, Mattawoman will fire ultra-low sulfur diesel fuel and employ
EPA Tier 2 or 3 approved engines.
Site preparation emissions were estimated based on AP-42 Section 11.9
equations for construction grading and earth moving operations, and the
hours of operation and vehicle miles traveled as provided by
Mattawoman. Unpaved road emissions were estimated based on AP-42
Section 13.2.2 equations and the number of vehicle miles travelled during
each year of construction activities. Emissions from diesel-fired
construction equipment and vehicles were based on EPA Tier 3 emission
rates, AP-42 Section 3.3, fuel use, and estimated hours of operation as
provided by Mattawoman.
Emissions associated with the construction activities as estimated by PPRP
are presented in Table 4-16. PPRP estimated emissions for particulate
were slightly lower than those estimated by Mattawoman, the State
accounted for annual rainfall under AP-42 Section 13.2.2 in unpaved haul
road emission calculations.
MD PPRP
4-28
Table 4-16
Emissions Associated with Construction Activities
Emissions (tpy)
Pollutant
Grading and
Earth
Moving
NOx
NMHC/VOC
SO2
CO
PM
PM10
PM2.5
HAPS
2.94
1.59
0.08
-
Construction
Traffic –
Unpaved
Roads
1.04
0.30
0.03
-
Construction
Equipment
Engines
Total
22.6
9.7
0.01
27.9
1.61
1.61
1.61
0.03
22.6
9.7
0.01
27.9
5.60
3.50
1.72
0.03
4.4
PREVENTION OF SIGNIFICANT DETERIORATION (PSD)
4.4.1
Applicability
Applicability of Prevention of Significant Deterioration (PSD) program for
the proposed Project is determined by evaluating whether there is a
“significant net emissions increase” of each PSD regulated pollutant
associated with the installation and operation of sources presented in
Mattawoman’s July 2013 CPCN application. As discussed in Section 3.4 of
this document, the Project is located in an attainment area for all
pollutants except ozone; therefore, applicability with PSD regulations is
evaluated for attainment pollutants against their respective Significant
Emissions Rate (SER). Under PSD, a project is considered major if the
project results in a significant emissions increase of any pollutant greater
than the SER for that pollutant. Pollutants with emissions equal to or
greater than the SER are subject to PSD requirements. Potential Project
emissions and PSD applicability thresholds are presented in Table 4-17.
MD PPRP
4-29
Table 4-17
PSD Applicability Analysis for the Project
Potential
Emissions
(tpy)
220.7
558.4
82.9
Significant
Emission Rate
(tons)
40
100
25
PSD
Triggered?
(Yes/No)
Yes
Yes
Yes
PM10 (Filterable and Condensable)
149.8
15
Yes
PM2.5 (Filterable and Condensable)
SO2
GHGs (as CO2e)
Hydrogen Sulfide
Sulfuric Acid Mist (SAM)
Lead
146.8
19.6
3,738,364
Negligible
11.2
0.014
100
40
100,000
10
7
0.6
Yes
No
Yes
No
Yes
No
Pollutants
NOX
CO
PM (TSP) (Filterable Only)
As noted in Table 4-17, potential NOX, CO, PM, PM10, PM2.5, SAM, and
GHG emissions exceed their pollutant-specific SER; therefore, the
proposed Project triggers PSD requirements and must:
4.4.2
•
Demonstrate use of BACT for pollutants with significant
emissions (Section 4.4.2);
•
Assess the ambient impact of emissions through the use of
dispersion modeling or other means. If the impacts are
significant, evaluate (through cumulative multi-source
modeling analysis) compliance with the NAAQS and
consumption of PSD increments (Section 4.4.3); and
•
Conduct additional impact assessments that analyze
impairment to visibility, soils, and vegetation as a result of the
modification, as well as impacts on Class I areas (Section 4.4.3).
Best Available Control Technology (BACT) Analyses
Based on potential emission estimates, the application of BACT is required
for NOx, CO, PM, PM10, PM2.5, SAM and GHG emissions from all
proposed Project emissions sources (combustion turbines and associated
HRSGs and duct burners, auxiliary boiler, emergency generator, fire water
pump engine, fuel gas heater, cooling tower, circuit breakers, and
equipment components). In the July 2013 CPCN application,
Mattawoman presented a control technology analysis for these sources,
which was supplemented with the January 2015 Supplemental Filing.
PPRP and MDE-ARMA reviewed Mattawoman’s control technology
analyses and requested clarification on certain aspects of the analyses.
MD PPRP
4-30
PPRP and MDE-ARMA’s BACT determination was developed based on
the information presented in Mattawoman’s July 2013 CPCN Application,
January 2015 Supplemental Filing, and additional information provided
by Mattawoman in response to PPRP Data Requests. This section
summarizes the BACT determination for the pollutants that trigger PSD
applicability.
NOx is reviewed for applicability with PSD for direct NOx emissions and
NA-NSR (along with VOCs) as a precursor to ozone. NA-NSR regulations
require the application of Lowest Achievable Emission Rate (LAER),
which is more stringent than BACT. The LAER determinations discussion
for NOx and VOCs is presented in Section 4.5 as those pollutants exceed
the significant emission levels for NA-NSR. In this section, a BACT
analysis for CO, PM, PM10, PM2.5, SAM, and GHG emissions is
presented.
4.4.2.1
BACT Analysis Process
BACT for any source is defined in COMAR 26.11.17.01(B)(5) as:
(a)…an emissions limitation, including a visible emissions
standard, based on the maximum degree of reduction for
each regulated NSR pollutant which would be emitted from
any proposed major stationary source or major modification
which the [MDE-ARMA], on a case-by-case basis, taking into
account energy, environmental, and economic impacts and
other costs, determines is achievable for that source or
modification through application of production processes or
available methods, systems, and techniques, including fuel
cleaning or treatment or innovative fuel combination
techniques for control of the pollutant.
(b) Application of best available control technology may not
result in emissions of any pollutant which would exceed the
emissions allowed by an applicable standard under 40 CFR
60 and 61.
(c) If the [MDE-ARMA] determines that technological or
economic limitations on the application of measurement
methodology to a particular emissions unit would make the
imposition of an emissions standard infeasible, a design,
equipment, work practice, operational standard, or
combination of these, may be prescribed instead to satisfy
the requirement for the application of best available control
MD PPRP
4-31
technology. This standard shall, to the degree possible, set
forth the emissions reduction achievable by implementation
of the design, equipment, work practice, or operation, and
shall provide for compliance by means which achieve
equivalent results.
BACT analyses are conducted using EPA’s “top-down” BACT
approach, as described in EPA’s Draft New Source Review Workshop
Manual (EPA, 1990). The five basic steps of a top-down BACT
analysis are listed below:
Step 1: Identify potential control technologies;
Step 2: Eliminate technically infeasible options;
Step 3: Rank remaining control technologies by control effectiveness;
Step 4: Evaluate the most effective controls and document results; and
Step 5: Select BACT.
The first step is to identify potentially “available” control options for each
emission unit triggering PSD, for each pollutant under review. Available
options consist of a comprehensive list of those technologies with a
potentially practical application to the emission unit in question. The list
includes technologies used to satisfy BACT requirements, innovative
technologies, and controls applied to similar source categories.
For this analysis, PPRP investigated the following sources to verify the
potential control technologies presented by Mattawoman as BACT:
•
EPA’s RACT/BACT/LAER Clearinghouse (RBLC) database;
•
EPA’s New Source Review website;
•
In-house experts;
•
State permits issued for similar sources that have not yet been
entered into the RBLC; and
•
Guidance documents and personal communications with state
agencies.
After identifying potential technologies, the second step is to eliminate
technically infeasible options from further consideration. To be
MD PPRP
4-32
considered feasible for BACT, a technology must be both available and
applicable.
The third step is to rank the technologies not eliminated in Step 2 in order
of descending control effectiveness for each pollutant of concern. If the
highest ranked technology is proposed as BACT, it is not necessary to
perform any further technical or economic evaluation. Potential adverse
impacts, however, must still be identified and evaluated.
The fourth step entails an evaluation of energy, environmental, and
economic impacts for determining a final level of control. The evaluation
begins with the most stringent control option and continues until a
technology under consideration cannot be eliminated based on adverse
energy, environmental, or economic impacts. The economic or
“cost-effectiveness” analysis is conducted in a manner consistent with
EPA’s OAQPS Control Cost Manual, Sixth Edition and subsequent revisions
(EPA, 2002).
The fifth and final step is to select as BACT the emission limit from
application of the most effective of the remaining technologies under
consideration for each pollutant of concern.
Mattawoman employed the five-step BACT process in their assessment of
BACT for the proposed Project. PPRP and MDE-ARMA agree with the
approach utilized in Mattawoman’s CPCN application submittals, and
supplemented with responses to data requests that were generated during
PPRP and MDE-ARMA’s review of the BACT assessment. A summary of
our analysis of Mattawoman’s conclusions to the BACT assessment is
discussed herein by emission source for each of the PSD pollutants.
PPRP and MDE-ARMA used the information provided in Mattawoman’s
July 2013 Application, January 2015 Supplemental Filing, and subsequent
responses to data requests to review the BACT determination for each
source, for each pollutant triggering PSD. These determinations are
summarized in Table 4-18 for PM, PM10, and PM2.5; Table 4-19 for CO;
Table 4-20 for SAM; and Table 4-21 for GHGs.
PPRP reviewed Mattawoman’s BACT analysis and have supplemented
this analysis with additional information based on review of the RBLC,
recently issued permits and other agency BACT determinations. PPRP
and MDE-ARMA’s review utilizes Mattawoman’s BACT analysis
approach, and either agrees with the BACT conclusions, supplements
Mattawoman’s conclusions, or indicates where we disagree with the
MD PPRP
4-33
conclusions and provides justification for the resulting BACT
determination for the proposed Project.
4.4.2.2
BACT Determinations
4.4.2.2.1
PM, PM10 and PM2.5 BACT
Particulate matter emissions are generated from each combustion source
and the mechanical draft cooling tower proposed by Mattawoman. The
following provides a summary of the BACT evaluation conducted for
each source of PM, PM10, and PM2.5 emissions.
Combustion Turbines
Filterable PM
There are several post-combustion particulate matter control systems
potentially feasible to reduce the filterable portion of PM, PM10, and
PM2.5 emissions from CTs. These including the following, listed below in
order of decreasing potential control efficiency:
•
Fabric filters/baghouse;
•
Electrostatic precipitators (ESPs);
•
Scrubber technologies; and
•
Cyclones/centrifugal collectors.
Fabric Filters/Baghouse
Fabric filters/baghouses use a filter material to remove particles from a
gas stream. The polluted gas stream flows through filters/bags onto
which particles are collected. Baghouses are typically employed for
industrial applications to provide particulate control at a relatively high
efficiency.
Electrostatic Precipitators (ESPs)
ESPs serve as a particulate collection devices and are used on a wide
variety of industrial sources, including boilers. An ESP is a particulate
control device that uses electrical forces to move particles out of the
flowing gas stream onto collector plates. The particles are given an
electric charge by forcing them to pass through a region of gaseous ion
flow. The term for this region of gaseous ion flow is the corona. An
MD PPRP
4-34
electrical field generated by electrodes at the center of the gas stream
forces the charged particles to the walls or plates of the ESP.
Removal of the particles collected on the plates of an ESP is required to
maintain sufficient area to continuously clean the flowing gas stream. The
removal of particles from the plates must be done in a manner to
minimize re-entrainment of the particles collected. The particles are
removed from the plate by “rapping” or knocking loose the particles from
the collector plates and the particles collected in a hopper, which is below
the plates.
Scrubber
Scrubbers can be employed to control particulate matter in certain
industrial applications. Wet scrubbers operate in such a manner that flue
gas passes through a water (or other solvent) stream whereby particles in
the gas stream are removed through inertial impaction and/or
condensation of liquid droplets on the particles in the gas stream.
Cyclones/Centrifugal Collectors
Cyclones/centrifugal collectors are generally used in industrial
applications to control large diameter particles (>10 micron). Cyclones are
designed based on the principle of imparting a centrifugal force on the gas
stream and entrained particles outward toward an outer wall. Upon
contact with an outer wall, the particles slide down the cyclone wall and
are collected at the bottom of the unit. The design of a centrifugal
collector provides for a means of allowing the clean gas to exit through the
top of the device. Cyclones are inefficient for the removal of small
particles.
Condensable PM
There are two types of add-on controls for controlling the condensable
portion of PM10 and PM2.5: catalytic oxidation and thermal oxidation.
These oxidation technologies are available to combust certain high
molecular weight condensable organics, thereby reducing condensable
PM emissions.
Thermal Oxidation/Catalytic Oxidation
Oxidation technologies involve the elevation of the temperature of a vent
stream to a sufficiently high enough level to allow for complete
combustion of condensable materials. Thermal oxidation typically
MD PPRP
4-35
requires temperatures in excess of 1,400°F for a residence of at least 0.5
seconds to achieve high destruction efficiency of condensables. Catalytic
oxidation systems employ a catalyst to accelerate the oxidation of
condensables and thereby require lower combustion chamber
temperatures (i.e., <1,000°F) to achieve destruction of condensables;
however, such systems require routine catalyst replacement.
Feasibility
Each of the technologies introduced in this section for controlling the
filterable portion of PM are generally available for application to CTs.
However, PPRP determined based on a review of the RBLC and other
recent permits issued for similar sources, that no gas-fired CTs have
installed post-combustion control technologies for PM. BACT for gasfired CTs is the use of good combustion practices to minimize PM
emissions. At this time, given that no post-combustion control sources
have been demonstrated in practice on a gas-fired CT, such technologies
are not deemed available for the Mattawoman CTs.
Thermal oxidation and catalytic oxidation are generally available to
control the condensable portion of PM from certain sources. However,
Mattawoman proposes to combust natural gas exclusively in an efficient
combustion unit. Adding a process to oxidize condensables from the
combustion of the natural gas fired in the CTs would generally only
introduce additional combustion emissions without any discernible
reduction in condensable PM. Given that the proposed CTs are highly
efficient combustion sources that would already have combusted available
condensables in the fuel stream, the use of an additional combustion
source (such as an oxidation control system) is not considered feasible for
the Mattawoman CTs.
In the July 2013 CPCN application and January 2015 Supplemental Filing,
Mattawoman also identified control technologies that could potentially be
used to reduce particulate matter emissions from combustion turbines.
Based on a review of EPA’s RBLC database and other recent permits,
Mattawoman determined that add-on emission controls for PM, PM10
and PM2.5 have yet to be installed on any gas-fired combustion turbine.
Therefore Mattawoman, presented in their application that installation of
add-on controls for particulate matter were not commercially
demonstrated on natural gas-fired CTs.
MD PPRP
4-36
BACT Proposal
Mattawoman proposed the use of pipeline quality natural gas and good
combustion practices as BACT for PM, PM10 and PM2.5 from the CTs.
The combustion of natural gas, with a lower ash and sulfur content than
other commonly used fuels (i.e., fuel oil, and coal), generates lower levels
of particulate matter emissions compared to other fuels. Mattawoman
proposed to achieve emissions of PM (filterable) of 8.9 lb/hr (0.0040
lb/MMBtu) without duct firing, and 13.9 lb/hr (0.0039 lb/MMBtu) with
duct firing, per CT. Mattawoman also proposed to achieve emissions of
PM10/PM2.5 of 17.9 lb/hr (0.0079 lb/MMBtu) without duct firing, and
27.7 lb/hr (0.0078 lb/MMBtu) with duct firing, per CT.
PPRP and MDE-ARMA confirmed, based on a review of the RBLC and
other recent permits for CTs (included in Appendix B), that there are no
instances of add-on controls determined as BACT for PM, PM10 or PM2.5
for CTs. PPRP’s review identified that lower PM, PM10 and PM2.5
emission limits have been included in permits for other CTs within the
US. However, these permits are for CTs of a different manufacturer, CT
type, model, or capacity (Brunswick, Calpine Russell City Energy Center,
Pioneer Valley Energy Center, Chugach, Effingham, Invenergy Nelson,
and Bridgeport Energy), or have yet to demonstrate the ability to achieve
the lower limits in practice (Palmdale, Oregon Clean Energy Center,
Moundsville, Moxie Energy-Freedom, CPV Wawayanda, Midland,
Thetford, and Woodbridge).
Certain other permits appear to have lower emission rates than proposed
by Mattawoman; however, the limits for these facilities are based solely on
filterable PM rather than Maryland’s definition of PM10 and PM2.5 which
includes filterable and condensable PM. These facilities include Carty
Plant, Kalama Energy Center, Moxie Patriot Generating Station, and
Rocky Mountain Energy.
Emission limits of PM, PM10, and PM2.5 from the proposed CTs are
dependent on the sulfur content of gas. Determination of sulfur content is
based on sampling data from fuel suppliers, as noted in the Mattawoman
CPCN application materials. The annual average sulfur content of the
natural gas supplied to Mattawoman for use in the CTs is projected to 0.25
grains/100 standard cubic feet (0.25 gr/100 scf). Comparison with the
sulfur contents in natural gas that are listed in the RBLC and other
recently issued permits indicates that the level proposed by Mattawoman
is equivalent to other recently permitted projects.
MD PPRP
4-37
PPRP and MDE-ARMA concur that the use of good combustion practices
and the exclusive use of pipeline quality natural gas constitutes BACT for
PM, PM10, and PM2.5. Mattawoman’s proposed BACT limits are based
on the CTs operating at 100 percent (100%) load, with and without duct
firing, and at an ambient temperature of 0 degrees F, which represents the
worst-case emissions associated with the CTs/HRSGs.
PPRP and MDE-ARMA recommend BACT emissions limits for particulate
matter including PM (filterable) of 8.9 lb/hr (0.0040 lb/MMBtu) without
duct firing, and 13.9 lb/hr (0.0039 lb/MMBtu) with duct firing per CT, as
well as PM10/PM2.5 of 17.9 lb/hr (0.0079 lb/MMBtu) without duct firing,
and 27.7 lb/hr (0.0078 lb/MMBtu) with duct firing per CT.
Mattawoman will be required to perform initial stack testing for PM using
EPA Method 5, and for PM10 and PM2.5 using EPA Method 201A/202 to
demonstrate compliance with the BACT limits. The averaging period for
PM by Method 5 will be based on a 3-hour block average (average of three
1-hour stack testing runs). However, given the longer run times
potentially required for Methods 201A/202, the averaging period for
PM10 and PM2.5 will be based on the duration of the three individual
stack test runs, the duration of which could run up to 8-hours each. PPRP
and MDE-ARMA is not providing a specific averaging period for PM10
and PM2.5 as the duration of the stack test could vary depending on the
ambient and stack conditions at the time of the test. Continuous
compliance with the BACT limits will be demonstrated based on data
from the annual stack tests.
Based on the information presented in the CPCN application, the
emissions of PM, PM10 and PM2.5 during startup and shutdown
conditions are expected to be no greater than during normal operations.
During periods of startup and shutdown, Mattawoman will be required to
take all reasonable efforts to minimize emissions. Startup and shutdown
emissions will be included in the facility-wide emissions cap.
Auxiliary Boiler
The auxiliary boiler will be fueled exclusively by pipeline quality natural
gas and will be designed to operate for 8,760 hours per year.
The combustion of natural gas, with a lower ash and sulfur content than
other commonly used fuels (i.e., fuel oil, and coal), generates lower levels
of particulate matter emissions compared to other fuels. In the July 2013
CPCN application, Mattawoman determined that add-on controls are not
considered commercially demonstrated for auxiliary boilers of a similar
MD PPRP
4-38
size firing natural gas only. Mattawoman proposed the use of pipeline
quality natural gas and good combustion practices as BACT for PM,
PM10, and PM2.5.
PPRP reviewed recent permits as well as determinations listed in the
RBLC database and concluded that there are no small natural gas-fired
boilers (10-100 MMBtu/hr) that currently employ post-combustion control
technologies for PM, PM10, or PM2.5 emissions. The determinations for
small boilers indicate that the use of clean fuels (i.e., low-sulfur, low-ash
content) and good combustion practices represents BACT for PM, PM10,
and PM2.5.
Mattawoman proposes a PM BACT emission limit of 0.0019 lb/MMBtu,
and PM10 and PM2.5 BACT emission limits of 0.0075 lb/MMBtu for the
auxiliary boiler. Based on a review of RBLC database, the PM, PM10, and
PM2.5 emission limits from similar-sized auxiliary boilers were generally
at or above the BACT limits proposed by Mattawoman for the auxiliary
boiler of 0.0019 lb/MMBtu for PM and 0.0075 lb/MMBtu for
PM10/PM2.5. Certain permits have limits lower than those proposed by
Mattawoman; however, those units are either much larger in heat input
capacity (Iowa Fertilizer Company), or have yet to be built or
demonstrated in practice (Berks Hollow, Pioneer Valley, CPV
Wawayanda, Thetford, Cricket Valley), or have limits that are based on
filterable PM rather than Maryland’s definition of PM10 and PM2.5 which
include filterable and condensable PM (Caithness). Therefore, these are
not comparable units to the proposed Mattawoman auxiliary boiler.
Two other boilers (Holland Board of Public Works, Warren County) had
slightly lower limits for PM10/PM2.5 at 0.007 lb/MMBtu. Similar to the
Mattawoman auxiliary boiler, these two units are natural gas fired and
employ good combustion practices to achieve the prescribed limits. PPRP
and MDE-ARMA consider that the minimal difference in emission limit
does not constitute a significant net environmental benefit, in particular
given that the proposed auxiliary boiler will fire exclusively pipeline
natural gas and employ good combustion practices.
PPRP and MDE-ARMA recommend BACT emission limits of 0.0019
lb/MMBtu for PM, and 0.0075 lb/MMBtu for PM10 and PM2.5, based on
a 3-hour block average basis. Mattawoman shall be required to obtain
vendor guarantees to demonstrate compliance with these BACT limits.
Fuel Gas Heater
MD PPRP
4-39
The fuel gas heater will be fueled exclusively by pipeline quality natural
gas. BACT for PM, PM10, and PM2.5 for the fuel gas heater is proposed
by Mattawoman as the exclusive use of pipeline quality natural gas and
good combustion practices. PPRP and MDE-ARMA reviewed the RBLC
database and recent permit determinations to evaluate if add-on controls
have been required to reduce particulate matter emissions from fuel gas
heaters. Based on this review, it was determined that the use of natural
gas and good combustion practices is considered BACT for PM, PM10,
and PM2.5 emissions for the fuel gas heater.
Mattawoman proposes a PM BACT emissions limit of 0.0019 lb/MMBtu,
and PM10 and PM2.5 BACT emissions limits of 0.0075 lb/MMBtu. Based
on PPRP and MDE-ARMA’s review of RBLC database, there were no
permits found with lower emissions limits than the proposed PM limit of
0.0019 lb/MMBtu, and PM10/PM2.5 BACT limit of 0.0075 lb/MMBtu for
similar-sized fuel gas heaters (10-100 MMBtu/hr firing rate).
PPRP and MDE-ARMA recommend BACT emission limits of 0.0019
lb/MMBtu for PM, and 0.0075 lb/MMBtu for PM10 and PM2.5, based on
a 3-hour block average basis. Mattawoman shall be required to obtain
vendor guarantees to demonstrate compliance with these BACT limits.
Emergency Engines
Mattawoman proposes to fuel the emergency generator and fire water
pump engine with ultra low sulfur diesel (ULSD) and employ good
combustion practices to maintain a maximum PM emission rate of 0.15
g/bhp-hr (0.20 g/kW-hr), and maximum PM10 and PM2.5 emission rates
of 0.18 g/bhp-hr. The PM emission rate represents a filterable portion
equivalent to the New Source Performance Standards (NSPS) for Internal
Combustion Engines under the 40 CFR Part 60 Subpart IIII PM limit.
PPRP calculated a BACT emission limit for PM10/PM2.5 of 0.17 g/bhp-hr
(0.23 g/kw-hr) which represents a filterable portion equivalent to the
NSPS Subpart IIII PM limit and a condensable portion equivalent to 0.02
g/hp-hr, as estimated based on EPA’s AP-42, Section 3.4 (October 1996).
A review of the RBLC and other recently permitted emergency engines
concludes that there are currently no facilities employing post-combustion
controls on internal combustion (IC) engines of similar size to those
proposed by Mattawoman to achieve BACT for particulate emissions.
Technologies that are listed in the summary of RBLC and recent permits
review, provided in Appendix B, rely on the use of good combustion
practices, NSPS compliant engines, limited operating hours, and fuels
such as ULSD, to achieve BACT for PM (filterable) and PM10/PM2.5
MD PPRP
4-40
(filterable and condensable). PPRP and MDE-ARMA concur with
Mattawoman’s proposed BACT for PM, PM10 and PM2.5 for the
emergency engines as compliance with NSPS for IC engines.
PPRP’s review found a wide-range of emissions rates for emergency
generators, with the lowest being 0.02 g/bhp-hr at both the Moxie Energy
and Moxie Liberty facilities. These facilities have not been built, nor have
the limits been demonstrated in practice. However, even if emissions
from the Mattawoman engines were limited to these lower levels (a
difference of 0.13 g/bhp-hr), the reduction would result in a decrease of
less than 0.11 tpy of emissions for the emergency generator (assuming 500
hours/year for emergency purposes, maintenance, and readiness testing).
PPRP’s review also found a range of emissions for fire water pump
engines, with the lowest being 0.07 g/bhp-hr at the Mankato Power
facility. This is a difference of 0.08 g/bhp-hr for PM and 0.1 g/bhp-hr
compared to the PM10/PM2.5 emission rates. If emissions from the fire
water pump were limited to these lower limits, it would result in an
emissions decrease of 0.01 tpy for PM, and 0.017 tpy for PM10/PM2.5
based on 500 hours of operation for emergency purposes, maintenance,
and readiness testing. PPRP and MDE-ARMA determined that there is no
material environmental benefit associated with requiring lower emission
rates for the emergency engines, given that these sources will be used for
emergency and testing purposes only.
PPRP and MDE-ARMA have determined that BACT for the emergency
generator and fire water pump engine is the exclusive use of ULSD fuel
along with good combustion practices, and limited hours of operation,
designed to achieve a PM emission limit of 0.15 g/bhp-hr (0.20 g/kW-hr),
and a PM10 and PM2.5 emission limit of 0.17 g/bhp-hr. The emergency
engines will be designed to meet these emission limits, and Mattawoman
will be required to supply a certification or similar information to
demonstrate compliance with these limits. To monitor hours of operation,
Mattawoman will be required to install a non-resettable operating hour
meter (or equivalent software) on each emergency engine.
Cooling Tower
Actual drift loss rates from wet cooling systems, including those proposed
by Mattawoman for this project, are affected by a variety of factors,
including the type and design of the cooling system, capacity, velocity of
air flow, density of the air in the cooling tower, and the total dissolved
solids (TDS) concentration in the circulating water.
MD PPRP
4-41
Mattawoman proposes to install a cooling tower equipped with highefficiency drift eliminators that will achieve a minimum of a 0.0005
percent (0.0005%) of the circulating water rate (0.0005 percent drift), based
on a review of the RBLC data and several other recently permitted cooling
towers in the U.S. PPRP and MDE-ARMA conclude that the levels
proposed by Mattawoman were either equivalent to or lower than those
for other permitted sources. Therefore, PPRP and MDE-ARMA concur
that BACT for the cooling towers is the installation of the high efficiency
drift eliminators with a drift loss of 0.0005 percent (0.0005%) of the
circulating water rate.
To ensure that the high efficiency drift eliminators are continued to
operate as designed and support the proposed BACT limit, Mattawoman
will be required to develop a maintenance procedure noting how often
and what procedures will be used to ensure the integrity of the drift
eliminators prior to operation of the equipment. This maintenance
procedure will be maintained on-site and made available to the State upon
request, as part of the operations and maintenance plan for the facility as
stated in the recommended licensing conditions.
Paved and Unpaved Roads
In the CPCN application, Mattawoman addressed fugitive dust emissions
associated with construction of the site on paved and unpaved roads
within the facility boundary. Mattawoman will utilize dust suppression
control methods that will include placement of gravel on roads, applying
dust suppressing chemicals or water to roads and other exposed surfaces,
or other methods, as needed. PPRP independently reviewed the
applicability of BACT for paved/unpaved roads.
Fugitive emissions from these activities are expected to be negligible, but
are required to be addressed as part of the PM/PM10/PM2.5 BACT.
Therefore, PPRP and MDE-ARMA determined PM /PM10/PM2.5 BACT
for these operations will be taking all reasonable precautions to minimize
particulate matter emissions from onsite roadways including, but not
limited to, the use of water or chemical suppression and sweeping (or best
management practices).
Proposed BACT determinations for PM, PM10 and PM2.5 are presented in
Table 4-18.
MD PPRP
4-42
Table 4-18
Proposed PM, PM10, and PM2.5 BACT Determinations
Emission
Source
Proposed BACT Limit
BACT Determination
PM (filterable):
8.9 lb/hr (without duct firing) and 13.9 lb/hr (with duct firing) (3hour block avg., Method 5 stack test or equivalent method
approved by MDE-ARMA)
CTs/HRSGs
PM10/PM2.5 (filterable + condensable): 17.9 lb/hr (without duct
firing) and 27.7 lb/hr (with duct firing) (3-test runs, Method
201A/202 stack test or equivalent method approved by MDEARMA)
All reasonable efforts shall be taken to minimize emissions during
startup and shutdown events. Startup and shutdown emissions
will be included in a facility-wide emissions cap.
PM (filterable): 0.0019 lb/MMBtu
(3-hour block average), Vendor provided performance guarantee
Auxiliary
Boiler
PM10/PM2.5 (filterable + condensable): 0.0075 lb/MMBtu (3-hour
block average), Vendor provided performance guarantee
PM (filterable): 0.0019 lb/MMBtu,
Vendor provided performance guarantee
Fuel Gas
Heater
PM10/PM2.5 (filterable + condensable): 0.0075 lb/MMBtu;
Vendor provided performance guarantee
PM (filterable): 0.15 g/bhp-hr (0.20 g/kW-hr)
Design specification and installation of a non-resettable hour meter
Emergency
Generator
PM10/PM2.5 (filterable + condensable): 0.17 g/bhp-hr (0.23 g/kWhr), Design specification and installation of a non-resettable hour
meter
PM (filterable): 0.15 g/bhp-hr (0.20 g/kW-hr)
Fire Water
Pump
Engine
PM10/PM2.5 (filterable + condensable): 0.17 g/bhp-hr (0.23 g/kWhr)
Cooling
Tower
NA
Paved/Unp
aved Roads
NA
MD PPRP
Exclusive use of pipeline
quality natural gas and good
combustion practices
Use of pipeline quality
natural gas and good
Use of pipeline quality
natural gas and good
Exclusive use of ULSD fuel,
good combustion practices,
limited hours of operation,
and designed to achieve
emission limits
Exclusive use of ULSD fuel,
good combustion practices,
limited hours of operation,
and designed to achieve
emission limits
High efficiency drift
eliminators (0.0005% drift rate
efficiency)
Minimize particulate matter
emissions from onsite
roadways including, but not
limited to, the use of water or
chemical suppression and
sweeping
4-43
4.4.2.2.2
CO BACT
Combustion Turbines
There are two practical methods for controlling CO emissions from
combustion processes: efficient combustion (also referred to as good
combustion) and add-on control equipment. Efficient combustion is
inherent in the design of a combustor system to enhance the combustion
reaction and minimize the formation of CO. Control equipment for CO
emissions from combustion turbines are described below. They are listed
in order of decreasing potential control efficiency.
•
Catalytic Oxidizer/Oxidation Catalyst;
•
Dry low-NOx (DLN) Combustors; and
•
EMxTM (formerly SCONOx).
Catalytic Oxidizer/Oxidation Catalyst
Catalytic oxidizers/oxidation catalyst are pollution control devices
installed downstream of a combustion system. This is a post-combustion
control process where CO emissions are reduced by allowing unburned
CO to react with oxygen at the surface of a precious metal. Combustion of
CO starts at about 300ºF, with an efficiency of ninety 90%occurring at
temperatures above 600ºF. The oxidation catalyst can be located directly
after the CT, with catalyst size dependent upon the exhaust flow,
temperature, and desired efficiency. Both efficient combustion and addon control can be used, alone or in combination, to achieve the various
degrees of CO emissions required.
Catalytic oxidation is the control technology most often used with gas
turbines and consists of a catalyst bed located in the HRSG downstream of
the burner where the temperature is in the range of 700 – 1100°F. The
oxidation catalyst causes a small pressure drop (approximately 1.5 inches
of water), which causes a slight loss in power output from the turbine. No
additional reactants are required since there is sufficient oxygen in the gas
stream for the oxidation reactions to proceed in the presence of the
catalyst. The catalyst is subject to loss of activity over time due to physical
deterioration or chemical deactivation. Oxidation catalyst vendors
typically guarantee catalyst life for three years. Oxidation catalysts are
considered technically feasible and available for CTs.
MD PPRP
4-44
Dry low-NOx (DLN) Combustors/Good Combustion Practices
While used primarily to minimize NOx emissions, DLN combustors and
good combustion practices in combination have surrogate impacts in
reducing CO emissions. DLN combustors and good combustion practices
are feasible and available for CTs.
EMxTM (formerly SCONOx)
One other add-on control technology that results in minor reductions in
CO emissions for CTs is EMxTM (formerly SCONOx). EMx™ is a catalytic
oxidation and absorption control technology that uses a platinum-based
oxidation catalyst coated with potassium carbonate (K2CO3) to oxidize
and remove both NOx and CO without a reagent such as ammonia. The
EMx™ system reduces CO emissions by oxidizing the CO to CO2. This
technology is primarily used for NOx reduction, but there has been
measurable oxidation of CO to CO2 with use of EMx™. However, the
demonstrated application for EMx™ is currently limited to combined
cycle combustion turbine units under 50 MW in size 9. The CTs proposed
for this Project are significantly larger, and as such, EMx™ is considered
technically infeasible for this proposed Project.
BACT Proposal
In the CPCN application, Mattawoman identified several control
technologies that could be installed to reduce CO emissions from the
combustion turbines. Oxidation catalyst systems have the highest control
efficiency of the control options available and applicable to CTs/HRSGs.
Mattawoman proposes the use of good combustion practices, oxidation
catalyst, and the use of efficient combustion turbine design as BACT for
CO. This control system is the most stringent emission control (highest
emission reduction), and therefore PPRP and MDE-ARMA agree with
Mattawoman’s determination on CO BACT.
Mattawoman proposed a BACT limit of 2.0 ppm @ 15%O2 with and
without duct firing. In Data Request No. 3-5, PPRP requested additional
justification from Mattawoman to support the proposed CO limits, as the
limits were greater than certain other comparable combustion turbines
(including non-Siemens units). In response to PPRP Data Request No. 3-5,
9
http://emerachem.com/application/gas-turbine/
MD PPRP
4-45
Mattawoman provided the following justification for the proposed CO
BACT limits:
•
Mattawoman indicated that it was not appropriate to compare the
proposed Siemens units with other make/model combustion
turbines as the operations and emission profiles are different; and,
•
The proposed BACT limits are consistent with the emissions
guarantees provided by Siemens.
The CTs identified by PPRP in the RBLC and other recently issued permits
with lower CO emission limits are either for CTs of a different
manufacturer, CT type, model, or capacity (Brunswick, Kleen Energy,
Warren County, Astoria Energy), or have not been built or demonstrated
in practice (Palmdale, Cove Point).
PPRP and MDE-ARMA concur that BACT for CO is the exclusive use of
an oxidation catalyst system and efficient combustion to achieve an
emission limit of 2.0 ppmvd @ 15% O2 with and without duct firing on a 3hour block average basis. This block 3-hour averaging period is consistent
with recently issued PSD permits. CO CEMS will be required to
demonstrate continuous compliance with the CO BACT limit.
During periods of startup and shutdown, CO emissions are higher due to
limitations surrounding both the ability to ensure good combustion
practices and the inability of the oxidation catalyst to operate efficiently at
lower temperature levels. The rate at which the CT starts up is
particularly affected by the ability of the corresponding HRSG to accept
heat. Therefore, a fast startup rate for the CT reduces the ability of the
HRSG to operate optimally.
To ensure optimal performance during normal operation, the CT startup
is designed such that it is held in a startup mode until it reaches a certain
operating point when good combustion practices can be achieved. This is
also the minimum temperature for operation of the oxidation catalyst.
PPRP and MDE-ARMA determined based on a review of other permits
and the RBLC database that post-combustion controls are not considered
technically feasible during startup and shutdown conditions. Therefore,
BACT for natural-gas fired CTs for startup and shutdown emissions is to
ensure that correct procedures are followed to allow for optimal
performance during normal operations, and that the emissions during
each startup and shutdown event will be minimized.
MD PPRP
4-46
PPRP and MDE-ARMA determined that the CTs will be subject to the
following limits during startup and shutdown:
•
CO emissions will be limited to 1,772 pounds per cold startup event,
1,461 pounds per warm startup event, and 1,216 pounds per hot
startup event, as determined by CEMS;
•
CO emissions will be limited to 156 pounds per shutdown event, as
determined by CEMS.
Compliance with all CO emission limits for the CTs will be demonstrated
using a CO CEMS. Emissions during startup and shutdown events must
be included in the facility-wide annual emission limit for CO.
Auxiliary Boiler
The control technologies available for CTs are also applicable for the
auxiliary boiler. Mattawoman proposed the use of good combustion
practices and exclusive use of natural gas as BACT for CO. Based on
PPRP and MDE-ARMA’s review of the RBLC database and other recent
permits, add-on controls for reducing CO emissions from auxiliary boilers
of similar size proposed for this project, have not been required to comply
with BACT.
In the CPCN application, Mattawoman proposed a CO BACT limit of
0.037 lb/MMBtu. PPRP reviewed RBLC database, and identified other
permits for auxiliary boilers with lower CO BACT limits, and required
Mattawoman to provide additional justification for the proposed CO
BACT limit. In response to PPRP Data Request 2-3, Mattawoman
provided information regarding a range of boilers found in the RBLC and
it was determined that while several boilers had lower CO limits than that
proposed by Mattawoman, these limits were in the Las Vegas CO
nonattainment area, and therefore met lower CO limits to avoid NA-NSR
permitting. In response to PPRP Data Request No. 3-6, Mattawoman
noted that generally for boilers of this size, as CO emissions decrease, NOx
emissions increase. Furthermore, in PPRP Data Request No. 3-6
Mattawoman noted that boilers with lower CO emissions limits have not
been demonstrated in practice.
PPRP and MDE-ARMA recommend a CO BACT limit of 0.037 lb/MMBtu
on a 3-hour block average basis for the auxiliary boiler. Mattawoman
shall obtain vendor guarantees to demonstrate compliance with the BACT
limit and emissions shall be calculated using fuel measurements.
Mattawoman shall also conduct annual combustion analysis and tune-ups
to ensure good combustion practices are maintained.
MD PPRP
4-47
Fuel Gas Heater
Similar to the auxiliary boiler, Mattawoman proposed the application of
good combustion practices as BACT for CO emissions from the fuel gas
heater. Based on a review of RBLC database and other recent permits,
PPRP and MDE-ARMA determined that add-on controls for reducing CO
emissions have not been installed for a small-sized heater such as that
proposed in this project.
Mattawoman proposes a CO BACT limit of 0.021 lb/MMBtu on a 3-hour
block average basis. PPRP and MDE-ARMA concurs that BACT is the
use of good combustion practices to achieve an emissions limit of 0.021
lb/MMBtu for the fuel gas heater based on a 3-hour block average basis.
Mattawoman shall obtain vendor guarantees to demonstrate compliance
with the BACT limit and emissions shall be calculated using fuel
measurements. Mattawoman shall also conduct annual combustion
analysis and tune-ups to ensure good combustion practices are
maintained.
Emergency Engines
Mattawoman proposed that BACT for CO for the 1,490 hp emergency
generator and the 305 hp fire water pump engine is an emission rate
equivalent to the engine limits provided in 40 CFR Part 60, Subpart IIII,
which is a value of 2.6 g/bhp-hr (3.5 g/kW-hr). The facility proposes to
operate the emergency equipment using ULSD fuel, with a fuel sulfur
content no greater than 15 ppm by weight.
Generally, for engines of the sizes proposed for the proposed Project, good
combustion practices are utilized to limit the generation of CO emissions.
Review of recent permits and the RBLC for similar equipment indicates
that good combustion practices have been determined to be BACT.
Certain BACT determinations identify lower emissions levels using good
combustion practices. For example, the lowest permitted limit found for
an emergency generator is for the Moxie Liberty project (which is not yet
constructed) that lists an emission rate for an emergency generator of 0.13
g/bhp-hr.
If emissions from the emergency generator were limited to these lower
limits, it would result in an emissions decrease of 2 tpy for CO (assuming
500 hours of operation for emergency purposes, maintenance, and
readiness testing).
MD PPRP
4-48
The lowest limit found for an emergency fire water pump is for Mankato
Energy that lists an emission rate of 0.25 g/bhp-hr. If emissions from the
fire water pump were limited to these lower limits, it would result in an
emissions decrease of 0.4 tpy for CO (based on 500 hours of operation for
emergency purposes, maintenance, and readiness testing).
Based on these findings, PPRP and MDE-ARMA concur that CO BACT for
the 1,490 hp emergency engine and 305 hp fire water pump is good
combustion practices to achieve NSPS Subpart IIII emission limit of 2.6
g/bhp-hr. Mattawoman will demonstrate compliance through the
implementation of the requirements listed under 40 CFR 60, Subpart IIII
for the emergency engines. The emergency engines will be designed to
meet these emission limits. To monitor hours of operation, Mattawoman
will be required to install a non-resettable operating hour meter (or
equivalent software) on each emergency engine.
A summary of proposed CO BACT determinations are presented in Table
4-19:
MD PPRP
4-49
Table 4-19
Proposed CO BACT Determinations
Emission
Source
Proposed BACT Limit
BACT Determination
2.0 ppmvd @ 15% oxygen (with and without duct firing) (3hour block average), except startup and shutdown events,
and demonstrated through the use of CO CEMS.
CTs/HRSGs
1,772 lb/event (cold startup), 1,461 lb/event (warm startup),
1,216 lb/event (hot startup), and 156 lb/event (shutdown) for
the entire plant
quality natural gas, use of an
oxidation catalyst and
efficient combustion
Take reasonable efforts to minimize emissions during startup
and shutdown periods. Emissions during startup and
shutdown events shall be measured using CO CEMS. Startup
and shutdown emissions shall be added to facility-wide
emissions cap and reported quarterly to MDE-ARMA.
Auxiliary
Boiler
0.037 lb/MMBtu (3-hour block avg.), vendor provided
performance guarantees
Fuel Gas
Heater
0.021 lb/MMBtu (3-hour block avg.), vendor provided
performance guarantees
Emergency
Generator
2.6 g/bhp-hr (3.49 g/kW-hr)
Design specification and installation of a non-resettable hour
meter
Good combustion practices
and designed to meet
emission limit
Fire Water
Pump Engine
2.6 g/bhp-hr (3.49 g/kW-hr)
Design specification and installation of a non-resettable hour
meter
Good combustion practices
and designed to meet
emission limit
4.4.2.2.3
Sulfuric Acid Mist (SAM) BACT
Combustion Turbines
Mattawoman proposes the exclusive use of pipeline quality natural gas
(0.25 gr S/100 scf annual average and 1.0 gr S/100 scf short-term
maximum) as BACT for the SAM emissions from the CTs/HRSGs. There
are two technologies potentially available to control SAM emissions from
combustion sources: fuel treatment and flue gas desulfurization (FGD)
systems. Fuel treatment is not technically feasible for the CT given that
MD PPRP
4-50
natural gas is already treated to remove sulfur compounds by pipeline gas
distributors. A review of recent permits and RBLC determinations
indicates that there are no applications of FGD technology to CTs.
Therefore, the exclusive use of natural gas is considered BACT for SAM.
PPRP and MDE-ARMA recommend separate BACT limits for the
CTs/HRSGs with and without a duct burner and propose a BACT limit of
4.6 lb/hr (without duct firing) and 5.6 lb/hr (with duct firing), except
during periods of startup and shutdown. These limits are specified on a
3-hour block average basis. Compliance with the BACT limits will be
demonstrated based on initial and annual stack tests using EPA Method 8
or equivalent method approved by MDE-ARMA.
Auxiliary Boiler/Fuel Gas Heater
There are no available add-on controls for controlling SAM from the
auxiliary boiler or fuel gas heater. Mattawoman proposes the exclusive
use of natural gas (0.25 gr S/100 scf annual average and 1.0 gr S/100 scf
short-term maximum) and good combustion practices as BACT for the
auxiliary boiler and fuel gas heater. PPRP and MDE-ARMA reviewed
RBLC database and other permits and agree with Mattawoman’s
determination on BACT for SAM emissions for the auxiliary boiler and
fuel gas heater.
Mattawoman did not propose short-term emission limits for the boiler or
fuel has heater. PPRP and MDE-ARMA calculated short-term SAM
emission levels based on SO2 emissions to establish emission limits. Based
on the natural gas sulfur content limit, BACT for SAM is determined to be
an emission limit of 0.18 lb/hr (0.004 lb/MMBtu) for the boiler and 0.058
lb/hr (0.004 lb/MMBtu) for the fuel gas heater. Mattawoman will obtain
vendor guarantees to demonstrate compliance with the BACT limits for
the auxiliary boiler and fuel gas heater. SAM emissions will be calculated
using fuel measurements and the vendor guaranteed emission rates.
Emergency Engines
There are no available add-on controls for controlling SAM from the
emergency diesel engines. Mattawoman proposes BACT for the
emergency engines as the use of ultra-low sulfur diesel fuel (0.0015 wt%
S), limited hours of operation and good combustion practices. PPRP and
MDE-ARMA agree with Mattawoman’s determination on BACT for SAM
emissions from the emergency generator and fire water pump engine.
MD PPRP
4-51
Mattawoman did not propose short-term emission limits for the
emergency engines. PPRP and MDE-ARMA recommend a BACT limit of
0.007 g/bhp-hr each for both the emergency generator and fire water
pump engine. The emergency engines will be designed to meet the
emission limit and Mattawoman will obtain vendor guarantees to
demonstrate compliance with the BACT limit. To monitor hours of
operation, Mattawoman will be required to install a non-resettable
operating hour meter (or equivalent software) on each emergency engine.
A summary of SAM BACT determinations is presented in Table 4-20.
Table 4-20
Emission Source
Proposed SAM BACT Determinations
Proposed BACT Limit
BACT Determination
Sulfur Content: 0.25 gr S/100 scf annual average
and 1.0 gr S/100 scf short-term maximum
CTs/HRSGs
Auxiliary Boiler
Fuel Gas Heater
4.6 lb/hr (without duct firing) and 5.6 lb/hr (with
duct firing); 3-hour block average basis; stack tests
using EPA Method 8 or equivalent method
approved by MDE-ARMA
0.18 lb/hr; 3-hour block average basis; vendor
performance guarantee
0.058 lb/hr; vendor performance guarantee
ULSD: 0.0015 wt% S
Emergency
Generator
Fire Water Pump
Engine
4.4.2.2.4
0.007 g/bhp-hr; Design specification and
installation of a non-resettable hour meter
ULSD: 0.0015 wt% S
0.007 g/bhp-hr; Design specification and
Exclusive use of pipeline-quality
natural gas
Exclusive use of pipeline quality
natural gas and good combustion
practices
natural gas and good combustion
practices
Use of ULSD fuel, good
combustion practices, and limited
hours of operation
Use of ULSD fuel, good
combustion practices, and limited
hours of operation
GREENHOUSE GAS BACT
Six individual greenhouse gases are regulated under PSD as GHGs: CO2,
CH4, N2O, hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and
sulfur hexafluoride (SF6). Typically, GHG emissions are listed in terms of
carbon dioxide equivalents (CO2e). GHG emissions associated with
MD PPRP
4-52
combustion equipment are limited to CO2, CH4 and N2O. In order to
calculate GHG emissions, global warming potential (GWP) values are
used to normalize emissions of pollutants such as CH4 and N2O that are
deemed to have a greater detrimental impact on a per pound basis than
CO2. The GWP for CO2 has a value of 1.0, CH4 have a value of 25, N2O
has a value of 298, and SF6 has a value of 22,800. The evaluation of
technologies to minimize GHG emissions from combustion sources
typically focuses on CO2 emissions and mechanisms to reduce CO2
emissions. This dominates the GHG emission value for combustion
equipment. As such, the BACT evaluation presented in this document
refers to CO2 as the primary GHG pollutant for the proposed
Mattawoman combustion equipment. Other non-combustion sources of
GHGs include components of the gas pipeline and circuit breakers that
contain SF6.
In general, there are two strategies available to minimize GHG emissions
from combustion equipment: add-on control via carbon capture systems
to strip CO2 from the flue gas stream for subsequent re-use or
sequestration and/or energy efficiency methods.
Carbon Sequestration and Capture
In general, the availability is limited for add-on control options to
potentially remove GHGs from an exhaust stream. Carbon capture and
sequestration (CCS), or re-use is the only potentially available add-on
control option at this time, and even this technology is limited in its
development.
In order to capture CO2 emissions from the flue gas, CO2 must first be
separated from the exhaust stream. A variety of technologies can
accomplish this, and may include the following:
•
Pre-combustion systems designed to separate CO2 and hydrogen in the
high-pressure syngas typically produced at integrated gasification
combined cycle power plants; and
•
Post-combustion systems that separate CO2 from flue gas such as:
o Chemical absorption through the use of an aqueous solution
of amines as chemical solvents; or
o Physical absorption through the use of an absorption process
called Rectisol or Selexol.
MD PPRP
4-53
Oxygen combustion can make separation easier. It employs oxygen
instead of ambient air for make-up air supplied for combustion in the
boiler.
While numerous carbon capture, storage, and beneficial CO2 use
demonstration projects are in various stages of planning and
implementation across the globe, including several in the U.S. that are
funded by the Department of Energy (DOE), the technologies needed for a
full-scale generating facility are not yet commercially demonstrated in
practice. In fact, President Obama formed an Interagency Task Force on
Carbon Capture and Storage, co-chaired by DOE and EPA, in early 2010 to
develop a federal strategy for overcoming the barriers to the widespread,
cost-effective deployment of CCS within 10 years. The Task Force’s
ultimate goal is to bring five to ten commercial demonstration projects
online by 2016.
After CO2 is separated, it must be prepared for beneficial reuse or
transport to a sequestration or storage facility, if a storage facility is not
locally available for direct injection. In order to transport CO2, it must be
compressed and delivered via pipeline to a storage facility. Although
beneficial reuse options are developing with solutions such as the use of
captured material to enhance oil or gas recovery from well fields in the
petroleum industry. However, currently, the demand for CO2 for such
applications is well below the quantity of CO2 that is available for capture
from electric generating units (EGUs).
Without a market to use the recovered CO2, the material would instead
require sequestration, or permanent storage. The geological formations in
the vicinity of the proposed Project provide limited if any alternatives to
adequately and permanently store recovered CO2. Sequestration of CO2 is
generally accomplished via available geologic reservoirs that must be
either local to the point of capture, or accessible via pipeline to enable the
transportation of recovered CO2 to the permanent storage location.
Storage facilities may include any of the following:
•
Geologic formations;
•
Depleted oil and gas reservoirs;
•
Unmineable coal seams;
•
Saline formations;
•
Basalt formations; or
•
Terrestrial ecosystems.
MD PPRP
4-54
There is active on-going research in Maryland for potentially suitable
geologic storage formations in the State. However, extensive
characterization studies are still needed to determine their extent and
storage potential for CO2. These studies would take several years of
investigation, including drilling characterization wells, and would likely
require small-scale injection testing before determining their full-scale
viability.
There are neither local geologic reservoirs, nor pipelines, dedicated to CO2
transport that is available in the vicinity of the proposed Project at this
time. In addition, carbon capture technologies have yet to be
demonstrated for a facility of similar size to the proposed Project. Even if
CCS was considered technically available, given the guidance from DOE
(August 2010 Report of the Interagency Task Force on Carbon Capture
and Storage), CCS for a 550 MW natural gas-fired CCCT facility increases
capital cost by an estimated $340 million and adds a 15% energy penalty.
Since the proposed Project CT capacity is similar to the unit presented in
the study, the estimated $340 million increase in capital cost to
accommodate CCS would be a significant portion of the total cost for the
CT systems. In addition, the annual operating costs for the system would
increase, given the 15% energy penalty associated with operating a CCS
system.
Therefore, options involving carbon capture and sequestration are not
currently considered feasible for any of the equipment proposed in the
CPCN Application.
Energy efficiency methods to minimize GHG emissions are provided on a
source-by-source basis. These are described in the following paragraphs.
Combustion Turbines
In the CPCN application, Mattawoman reviewed several emission control
options for reducing GHG emissions. These included CCS, clean fuels,
energy efficiency design, practices and procedures, insulation, minimizing
fouling of heat exchange surfaces, minimizing vented steam and repairing
steam leaks. Based on this review, Mattawoman determined that add-on
control technologies or CCS were either not technically feasible or were
cost prohibitive, and PPRP and MDE-ARMA agree with this conclusion.
PPRP and MDE-ARMA identified the following available technologies for
consideration in minimizing GHGs from CTs which focus on energy
efficiency solutions and clean fuel options. An emissions reduction
strategy focused on energy efficiency options primarily focuses on
MD PPRP
4-55
increasing the thermal efficiency of a combustion turbine that would
thereby require less fuel for a given output, resulting ultimately in lower
emissions of GHGs. There are several potential strategies for improving
energy efficiency, including: selection of a more efficient electric
generating unit, combustion air cooling, or cogeneration/combined heat
and power techniques. Separately, the selection of lower carbon
containing fuels, such as natural gas, provides the opportunity for
additional GHG emission reductions. This is in contrast to coal-fired
combustion units. This section outlines these potential strategies with
respect to feasibility for the proposed Project.
More Efficient EGU
Maximizing EGU efficiency is an alternative available to reduce the
consumption of fuel required to generate a fixed amount of output. There
are efficiency losses inherent in a combined cycle CT design of the turbine
and the heat recovery systems. The mechanical input to the compressor
consumes energy and is integral to how a CT works. Therefore, there is
no opportunity for efficiency gains other than the differences in design
between manufacturers or models. Heat recovery in the exhaust is
another point of efficiency loss that is dependent on design of the heat
recovery system and varies between manufacturers and models.
Efficiency of turbines employed as part of an EGU can vary widely. One
alternative to reduce CO2 emissions is to maximize turbine efficiency
through various design techniques. Any increase in energy efficiency
within the operation of the turbine yields reductions in the generation of
CO2 emissions on a per unit output basis. For example, turbine suppliers
offer several different models of combustion turbines having a variety of
efficiency ratings.
EPA published guidance that evaluated the availability of high efficiency
combustion turbines with recognized thermal efficiencies in the range of
50% to over 56%. While the guidance addressed applications where an
increased efficiency was achieved via design, there are a variety of other
factors that may render an alteration to the combustion turbine design
infeasible for certain applications. This is true in the case of the proposed
Project. However, at this time, the selection of a more efficient EGU is
considered a technically feasible option for the proposed Project.
Combustion Air Cooling
During summer months, a common method used to improve energy
efficiency of combustion turbines is to cool the combustion air prior to
MD PPRP
4-56
entering the combustion turbine. Cooling the combustion air via heat
exchange systems maximizes the expansion of the air molecules and
enhances the work these expanding gases perform on the turbine blades.
Hence higher amounts of electricity are produced. A higher amount of
electricity generated improves the overall efficiency of the EGU. Based on
general guidance available with respect to combustion air cooling,
achievable reductions in fuel usage and CO2 emissions could be in the
range of 10% to 15% (RTP, 2009). As such, while this technology is
considered technically feasible, other options - such as a more efficient
EGU - are considered more effective in terms of overall net environmental
benefit.
Cogeneration / CHP as a CO2 Reduction Technique
Combined Heat and Power (CHP) is a technique involving the operation
of a combustion system to generate heat for electric power generation, as
well as to provide thermal energy to a process. The electric power is
distributed for use, while thermal energy is used locally to support
heating systems or industrial processes. A CHP system allows for the use
of energy in the form of heat to provide thermal energy that would
otherwise be lost in cooling water for a traditional EGU. For combustion
turbine systems, the more likely CHP technique would be to provide
space heating for nearby buildings or to provide makeup heat to nearby
coal-fired EGUs (likely application for power plants with CT and coal
fired EGUs onsite). The use of this otherwise lost heat would thereby
improve the overall efficiency of the EGU or process and, subsequently,
reduce overall CO2 emissions, on an equivalent basis.
The use of a CHP system provides an opportunity to extract additional
energy from heat otherwise lost in a traditional EGU. This type of system
however does require the removal of steam from the steam turbine, which
would thus reduce the magnitude of electric power generation recognized
in the CHP. This electrical energy is instead transformed to thermal
energy for use on a more local basis. The advantage of a CHP system over
a traditional EGU operation is the net improvement of overall fuel
efficiency.
Since Mattawoman is already employing HRSGs as a means to recover
otherwise lost heat, there is no remaining heat for use in a CHP system.
For a CHP system to be beneficial there must be a local need for thermal
energy, as thermal energy cannot be effectively transported over extended
distances. Given the proposed selection of a more efficient CT by
Mattawoman for the proposed Project, there is no reasonable net
environmental benefit of a CHP system for this application.
MD PPRP
4-57
Use of Lower Carbon-Containing Fuels
CO2 is produced as a combustion product of any carbon-containing fuel.
All fossil fuels contain varying amounts of fuel bound carbon that is
converted during the combustion process to produce CO and CO2. The
use of gaseous fuels (such as natural gas, process gas, refinery gas, or
syngas derived from higher carbon containing solid fuels) instead of
higher carbon-containing fuels (such as coal, pet-coke or fuel oils (residual
or distillate)) is an additional potentially feasible alternative to reduce the
generation of CO2 emissions from combustion turbines.
Natural gas combustion results in lower GHG emissions than coal
combustion (117 lb/MMBtu versus 210 lb/MMBtu, based on 40 CFR 98
Subpart C). The use of lower carbon containing fuels in combustion
turbines is an effective means to reduce the generation of CO2 during the
combustion process. The use of lower carbon-containing fuels is a
potentially technically feasible option for the proposed Project.
Mattawoman proposes the exclusive use of pipeline-quality natural gas,
which is a lower carbon containing fuel and installation of a highefficiency CT model (Siemens “H” class) as BACT for the GHG pollutants.
PPRP reviewed the RBLC database and recent permits issued for
combined cycle CTs to identify what BACT limits have been permitted.
In the CPCN application, Mattawoman proposed a GHG BACT limit of
865 lb of CO2/MWh (gross) with and without duct firing on a 12-monthly
rolling average basis, as well as a heat rate limit of 6,793 Btu/kWh (net,
LHV).
PPRP reviewed recent permits to identify applicable BACT limits and
associated compliance demonstration approaches. Table 4-21 summarizes
the determinations of GHG BACT for these recently permitted projects
and displays the heat rates for the CTs. The heat rates summarized below
demonstrate that the value proposed by Mattawoman is among the lowest
documented for CTs, at a level of 6,793 Btu/kWh. The operational
conditions specified for the CTs vary significantly. For example, some
limits were specified for no duct firing (Moxie Energy LLC’s Liberty and
Freedom facilities). Additionally, there were different compliance
margins assumed in the establishment of heat rate limits. In particular,
the degradation factors to account for the limits which can be achieved
over the life of the equipment significantly influence the heat rate limits.
maintenance overhauls.
MD PPRP
4-58
Initial compliance with the heat rate limitation shall be demonstrated
using ASME PTC 46 test method. Mattawoman will be required to
evaluate thermal efficiency of the turbines by conducting an annual
thermal efficiency test, and comparing the results to the design thermal
efficiency value. The results of the annual test shall be submitted to MDEARMA.
In addition to the heat rate limitation, PPRP and MDE-ARMA are also
proposing an emission rate limitation of 865 lb of CO2/MWh (gross) on a
12-month rolling average basis. This emission rate is less than the
proposed GHG NSPS limitation of 1,000 lb/MWh 10.
Mattawoman proposed compliance with the emission rate through
continuous measuring and recording of fuel flow rates using certified flow
meters and carbon content of the fuel combusted to determine CO2 mass
emission rates (40 CFR Part 75). PPRP and MDE-ARMA propose that
Mattawoman demonstrate compliance with the emission rate by
measuring the CO2 emissions using a certified CO2 CEMS and
contemporaneous generation load (MWh) to calculate the emission rate
(lb/MWh). Furthermore, a GHG facility-wide emission cap of 3,738,364
tons CO2e will be required on a 12-monthy rolling emissions basis,
measured utilizing a CO2 CEMS to continuously monitor and record CO2
emissions at all times when the CTs/HRSGs are operating, including
startup and shutdown events.
The CO2 CEMS will be installed and operated as specified in 40 CFR 75 to
monitor CO2 emissions. The CO2 CEMS will operate at all times,
including during periods of startup and shutdown, and data from the
CEMS will be used to calculate CO2 emissions from the CTs. Methane and
N2O emissions from the CTs will be calculated in accordance with the
methodology and emission factors noted in 40 CFR 98, Subpart D. On a
monthly basis, fuel consumption, coupled with the appropriate emission
factors and global warming potentials (currently 25 for CH4 and 298 for
N2O), will be used to calculate CH4 and N2O emissions. These emission
rates, summed with the monthly CO2 emissions from the CEMS, will
establish GHG emissions from the CTs on a CO2e basis. GHG emissions
will be calculated for the CTs utilizing the methodology and emission
factors noted in 40 CFR 98, Subpart D.
10 EPA, 2012. Standards of Performance for Greenhouse Gas Emissions for New Stationary
Sources: Electric Utility Generating Units, FR 22392.
MD PPRP
4-59
Table 4-21
Recent GHG Permit Determinations
Degradation
BACT Heat
Rate
%
Btu/kWh
Mitsubishi M501 GAC ; 3442
MMBtu/hr ; 1400 MW NGCC
3.4% - CT
1.2% - Aux Power
7.1% Steam Turbine
7500
Cricket Valley Energy Project,
Dover, NY
F-class CT; 2000 MMBtu/hr, NG
only
12.80%
7605
Calpine Corporation Channel
Energy Center
Siemens FD3-Series 501F CTG; 180
MW
Calpine Corporation Deer
Park Energy Center
Siemens FD3-Series
6%
FPL Port Everglades
NG Turbine, 500 MW, 8424
MMBtu/hr
5%
Green Power Stonewall
GE 7FA.05 or Siemens SGT6-5000F5
3.4% CT
1.2% Aux Power
7.1% Steam Turbine
Huntington Beach Energy
Project
Mitsubishi 501DA
10%
Lower Colorado River
Authority
GE 7FA, 195 MW, NG CC CT
5%
Oregon Clean Energy Center
TBD, 2277 MMBtu/hr max
7409
Palmdale
GE 7FA NG CTG
7319
Russell City Energy Center
Siemens/Westinghouse 501F, 2038.6
MMBtu/hr, NG
Sevier Power Company
GE Frame 207FA or Siemens 5000F(4)
St. Joseph Energy Center
2300 MMBtu/hr CCCT
12.80%
Wolverine Sumpter Power
Plant
NG CC CT, 922.78 MMBtu/hr
6%
Woodbridge Energy Center
GE 207FA.05, 2307 MMBtu/hr
3.3% design
6% efficiency loss
3% variability in
operation
Pacificorp Energy Lake Side
Power Plant
NG CC CTG
Facility
Turbine
Virginia Electric and Power
Company - Brunswick Plant,
VA
MD PPRP
7730
12.80%
7728
7340 (w/o DB)
7780 (w/DB)
7720
7730
7515
7646
7605
8095
4-60
Degradation
BACT Heat
Rate
%
Btu/kWh
Facility
Turbine
Tenaska Brownsville Partners
LLC
Mitsubishi 501GAC, 2903
MMBtu/hr
7,874
Moundsville Combined Cycle
Power Plant
GE 7FA.04, 2159 MMBtu/hr
6,772
Palmdale Hybrid Power
Plant
GE 7FA, 1736 MMBtu/hr
7,319
Brunswick County Power
Station
Mitsubishi 501GAC, 3442
MMBtu/hr
7,500
Auxiliary Boiler and Fuel Gas Heater
Mattawoman indicated in their application that there is currently no
technically feasible add-on control technology to reduce GHG emissions
from the auxiliary boiler and fuel gas heater, given the current technical
and economic issues discussed for the CTs with respect to the use of CCS
techniques. Other methods to reduce GHGs from the auxiliary boiler and
fuel gas heater include efficient boiler design, cleaner fuels and good
combustion practices, all of which Mattawoman proposes for the auxiliary
boiler and fuel gas heater.
Based on a review of recent permits, PPRP and MDE-ARMA determined
that Mattawoman’s proposed BACT is consistent with other permits for
auxiliary boilers and fuel gas heaters. Therefore, PPRP and MDE-ARMA
agree with Mattawoman’s BACT determination. GHG emissions from the
auxiliary boiler and fuel gas heater will be minimized through the use of
pipeline-quality natural gas, as well as good combustion practices and the
selection of an efficient design.
To demonstrate compliance with GHG BACT, Mattawoman will conduct
annual combustion tuning on the auxiliary boiler and fuel gas heater, as
well as monitor fuel use. GHG emissions on a CO2e basis from the
auxiliary boiler and fuel gas heater will be calculated based on the
methodology included in 40 CFR 98, Subpart C, with the emissions
included in the 12-month rolling CO2e limit for the Project.
Emergency Engines
Mattawoman indicated that there is currently no technically feasible addon control technology to reduce GHG emissions from emergency engines.
Therefore, Mattawoman proposes to limit GHG emissions from the 1,490MD PPRP
4-61
hp emergency generator and 305-hp fire water pump engine through the
use of good combustion practices and limited hours of operation. Based
on a review of recent permit determinations, PPRP and MDE-ARMA
agree with Mattawoman’s BACT determination.
This GHG BACT requirement is similar to recently permitted projects that
include diesel fuel-fired emergency engines. To demonstrate compliance
with the GHG BACT determination, Mattawoman will maintain the
emergency generator and fire water pump engine in accordance with
manufacturer’s specifications. GHG emissions on a CO2e basis from the
emergency engines will be calculated based on the methodology included
in 40 CFR 98, Subpart C and included in the 12-month rolling CO2e limit
for the Project.
Equipment Leaks
Leaks from natural gas piping components have been identified as
potential sources of GHG emissions. Natural gas piping components
include potential fugitive emissions of CH4 and CO2 from rotary shaft
seals, connection interfaces, valve stems, and similar points. Mattawoman
provided a BACT determination for fugitive components in response to
PPRP Data Request No. 1-2 which outlines the implementation of an
Audio, Visual, Olfactory (AVO) program to detect the presence of fugitive
leaks and mitigating emissions from fugitive components.
Currently, there are two levels of leak monitoring programs available to
mitigate GHG emissions from fugitive components: AVO monitoring or a
Leak Detection and Repair (LDAR) program. L detection and repair
(LDAR) programs utilizing handheld analyzers or alternative remote
sensing technology are available; given the small amount of fugitive GHG
emissions projected from the natural gas pipeline (0.0013% of the total
facility-wide potential GHG emissions on a CO2e basis), an AVO program
is suitable. Due to the presence of mercaptans in the natural gas, an AVO
program provides an effective method of detecting, identifying and
correcting leaks in the natural gas pipeline system. PPRP and MDEARMA recommend a condition that requires the AVO program to be
developed, conducted, and documented on a weekly basis. Leaks
identified from the AVO inspections shall be repaired within five days of
discovery, and the repairs documented and records maintained.
Fugitive emissions from the natural gas pipeline will be calculated
utilizing the methodology and emission factors of 40 CFR 98, Subpart W,
Petroleum and Natural Gas Systems, Table 2-4 of EPA’s Protocol for Equipment
Leak Emission Estimates or other methods approved by MDE-ARMA.
MD PPRP
4-62
Monthly GHG emissions associated with fugitive components will be
added to the facility wide total to determine compliance with the 12month rolling total emissions cap.
Circuit Breakers
Mattawoman indicated that state-of-the-art circuit breakers circuit
breakers containing SF6 will be used and proposes GHG BACT as the use
of leak detection and density alarms to minimize GHG emissions from
circuit breakers. The circuit breakers are designed to meet American
National Standards Institute (ANSI) C37.013 standard for high voltage
circuit breakers. PPRP and MDE-ARMA agree that circuit breakers
designed to meet ANSI C37.013 or equivalent and density alarms to detect
and minimize SF6 leaks and implement repair of any identified leaks
within five days of discovery, represents BACT.
Fugitive emissions from the circuit breakers will be calculated utilizing the
methodology of 40 CFR Part 98 Subpart DD, Electrical Transmission and
Distribution Equipment Use and will be added to the facility wide total to
determine compliance with the 12-month rolling period emissions cap.
Facility-Wide CO2e Limit
GHG emissions from the CTs/HRSGs, auxiliary boiler, fuel gas heater,
emergency generator, fire water pump engine, circuit breakers, and
fugitive emissions from the natural gas piping components shall be
limited to 3,738,364 tons (CO2e) in any consecutive rolling 12-month
period, as part of GHG BACT for the project.
CO2 emissions for the CTs/HRSGs shall be based on the use of a CO2
CEMS. CH4 and N2O emissions from the CTs will be calculated in
accordance with the methodology and emission factors noted in 40 CFR
98, Subpart D.
CO2, CH4, and N2O emissions from the remaining sources will be
calculated in accordance with the methodology and appropriate emission
factors noted in 40 CFR 98, Subparts C, D, W, and DD. On a monthly
basis, fuel consumption, coupled with the respective emission factors and
global warming potentials (25 for CH4 and 298 for N2O), will be used to
calculate the CH4 and N2O emissions on a CO2e basis.
Mattawoman will be required to track fuel usage in all the combustion
sources, and calculate consecutive rolling 12-month CO2e emissions to be
included in the quarterly reports submitted to MDE-ARMA.
MD PPRP
4-63
A summary of proposed GHG BACT limitations for all sources is
MD PPRP
4-64
Table 4-22
Emission
Source
Proposed GHG BACT Determinations
Proposed BACT Limit
BACT Determination
865 lb/MW-hr (gross), rolling 12-month period, CO2
CEMS;
CTs/HRSGs
Heat rate: 6,793 Btu/kWh (net, LHV)
Facility-wide CO2e emissions limit of 3,738,364 tons
(12-month rolling period)
Use of exclusively pipeline-quality
natural gas and installation of highefficiency CT model (Siemens “H”
Class)
Auxiliary Boiler
Annual combustion tuning.
CO2e emissions using 40 CFR Part 98 Subpart C to
comply with facility-wide emissions cap
natural gas, efficient boiler design
and good combustion practices
Fuel Gas Heater
Annual combustion tuning.
natural gas, efficient heater design
and good combustion practices
Emergency
Generator
Use of good combustion practices
Fire Water Pump
Engine
Use of good combustion practices
Equipment
Leaks
CO2e emissions using 40 CFR Part 98 Subpart W or
EPA’s Protocol for Equipment Leak Emission
Estimates or other MDE-ARMA approved methods
to comply with facility-wide emissions cap
Implement an AVO program
Circuit Breakers
CO2e emissions using 40 CFR Part 98 Subpart DD to
State-of-the-art circuit breakers with
leak detection and density alarms.
4.4.3
NAAQS and PSD Increment Compliance Demonstration
4.4.3.1
Prevention of Significant Deterioration Air Quality Modeling Analysis
The proposed Mattawoman project triggers New Source Review (NSR)
and Prevention of Significant Deterioration (PSD) permitting
requirements. The project triggers PSD requirements for GHG, NO2,
PM10, PM2.5, and CO. Mattawoman consequently completed relevant
modeling analyses for NO2, PM10, PM2.5, and CO using the most recent
version of the EPA approved AERMOD (Version 14134) refined
dispersion model.
MD PPRP
4-65
Mattawoman has also conducted Class I area modeling using CALPUFF
version 5.8, the EPA approved version of the CALPUFF dispersion model
suitable for long range modeling analyses (i.e., distances greater than 50
km). Class I areas included in the modeling analysis are Shenandoah
National Park, Brigantine National Wildlife Refuge (NWR), James River
Face NWR, Dolly Sods National Wilderness Area (NWA), and Otter Creek
NWA.
Mattawoman submitted an air quality modeling protocol to PPRP and
MDE-ARMA on September 25, 2012. The modeling methodologies
detailed in the protocol were approved by PPRP and MDE-ARMA in an
email to Mattawoman’s consultant dated November 26, 2012 from John
Sherwell at PPRP.
In November 2014, the Washington DC, VA, MD PM2.5 nonattainment
area was redesignated to maintenance/attainment from a status of
nonattainment. Consequently, emissions from the proposed Project
became applicable to PSD requirements. In anticipation of the
redesignation, Mattawoman submitted a PM2.5 air quality modeling
protocol to PPRP and MDE-ARMA in October 2014. The protocol was
accepted by PPRP and MDE-ARMA in November 2014, with the
assumption that EPA Region III comments would be addressed in the air
quality modeling analysis and report.
4.4.3.2
Review of Air Quality Modeling Methodology
4.4.3.2.1
Model Selection
Mattawoman utilized the latest version of the AERMOD (version 14134)
dispersion model for all analyses conducted in the CPCN application,
with the exception of the Class I analyses which used CALPUFF version
5.8. Mattawoman utilized all the latest versions of the supporting
processing programs for AERMOD, including AERMET version 14134,
AERSURFACE version 13016, AERMINUTE version 14337 (for
meteorological data processing), and AERMAP version 11103 (for receptor
elevations and hill scales). PPRP and MDE-ARMA approve of the use of
the selected models and supporting processing programs, and agree that
the use of these models represents a best practice approach for
determining the impacts of the proposed Project on air quality.
MD PPRP
4-66
4.4.3.2.2
Meteorological Data for Air Quality Modeling
AERMOD requires the use of representative meteorological data.
Mattawoman used meteorological data from Reagan National Airport
(KDCA) in Washington, DC as the source of surface-based input
meteorological data in the air quality modeling analysis. MDE-ARMA has
supplied Mattawoman with the meteorological data for KDCA processed
through AERMET for use in their air quality modeling analysis. MDEARMA processed the KDCA data for 2009-2013 in conjunction with upper
air data from Sterling, VA, and followed all EPA recommended practices
outlined in the AERMOD Implementation Guidance, including the use of
AERSURFACE and one-minute ASOS archive data. As part of the review
of the CPCN application, PPRP has independently processed the
meteorological data from KDCA and Sterling, VA, as outlined in the
following sections of this report.
4.4.3.2.2.1
Meteorological Data Representativeness
The Automated Surface Observation System (ASOS) station at Reagan
National Airport (KDCA) is located approximately 24 km to the northwest
of the proposed Mattawoman Energy Center. Meteorological data from
KDCA have previously been utilized by CPCN applicants for this region
of lower Maryland, notably the recent CPCN application for the Keys
Energy Center, located less than 2 km to the northeast of the proposed
Mattawoman Energy Center site. There are no terrain features between
the KDCA ASOS station and the proposed Mattawoman Energy Center
that would significantly affect regional wind patterns, and there are no
local terrain features present at either site that would significantly affect
local winds.
Differences in land use characteristics between KDCA and the
Mattawoman Energy Center were investigated to determine if these
differences could significantly affect AERMOD modeled concentrations.
The AERMET land use processor AERSURFACE was used to summarize
the Bowen ratio, albedo, and surface roughness values associated with
KDCA and the proposed site. A general comparison of these values is
provided in Table 4-23. It should be noted that these values were
determined for comparison purposes only. The procedures used in
AERSURFACE to support the actual AERMET processing are described in
Section 4.4.3.1.2.2 of this report.
MD PPRP
4-67
Table 4-23
Micrometeorological Variables Comparison
Airport - KDCA
Month
1
2
3
4
5
6
7
8
9
10
11
12
Albedo
0.16
0.16
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.15
0.16
Bowen
Ratio
0.74
0.74
0.6
0.6
0.6
0.58
0.58
0.58
0.74
0.74
0.74
0.74
Surface
Roughness
0.007
0.007
0.009
0.009
0.009
0.01
0.01
0.01
0.009
0.009
0.009
0.007
MEC Site
Albedo
0.16
0.16
0.15
0.15
0.15
0.16
0.16
0.16
0.16
0.16
0.16
0.16
Bowen
Ratio
0.83
0.83
0.58
0.58
0.58
0.4
0.4
0.4
0.83
0.83
0.83
0.83
Surface
Roughness
0.38
0.38
0.48
0.48
0.48
0.569
0.569
0.569
0.569
0.569
0.569
0.38
Table 4-23 shows notable differences for Bowen ratio and surface
roughness between the two sites, largely due to the presence of water
from the Potomac River at KDCA. PPRP conducted a screening analysis
using AERMET and AERMOD to determine the effect these differences in
micrometeorological variables would have on modeled concentrations. In
order to conduct this sensitivity analysis, AERMOD was executed for the
Project sources using two versions of AERMET meteorological data, one
version processed using the assumptions presented in Section 4.4.3.1.2.2 of
this report, the other with the same assumptions with the exception of the
micrometeorological variables, which were based on an AERSURFACE
run associated with the Mattawoman Energy Center Site rather than
KDCA. It was discovered that when micrometeorological variables
associated with the proposed Site were input into AERMET, the resulting
highest 1-hr modeled concentration in AERMOD were approximately
thirty-four percent (34%) lower than the result from AERMOD using
KDCA micrometeorological variables. Similarly, the highest 24-hr
AERMOD modeled concentrations were approximately forty-six percent
(46%) lower using the proposed Site data. PPRP believes these AERMOD
sensitivity results indicate that the KDCA meteorological data are
conservatively representative of the proposed Mattawoman Energy
Center Site.
As discussed above, the differences in land use and resulting
micrometeorological variables result in an inherent conservativeness with
respect to maximum modeled concentrations. Also, the lack of significant
terrain around both KDCA and the proposed site, indicate that KDCA is
regionally representative of the winds in the area of the proposed Project.
MD PPRP
4-68
PPRP asserts that the meteorological data from KDCA are adequately
representative of the region of lower Maryland, and are appropriate for
use in an air quality modeling analysis in support of the Mattawoman
Energy Center CPCN application.
4.4.3.2.2.2
AERMET Processing
PPRP has processed the meteorological data for KDCA (WBAN 13743)
with 5 years of recent data (2009-2013) with corresponding upper air data
from the NWS station in Sterling, VA (WBAN 93734). The latest version
of the EPA AERMET (version 14134) meteorological data processor was
used. Table 4-24 shows the data characteristics of the KDCA
meteorological data. A high level of data completeness and few calm data
are observed. A 5-year wind rose for KDCA is presented in Figure 4-2.
The prevailing wind is from the south and southwest. The specific
procedures and assumptions used by PPRP to process the KDCA
meteorological data in AERMET are described in the following
paragraphs.
Figure 4-2
MD PPRP
5-year Wind Rose (2009-2013): Reagan National Airport
(KDCA)
4-69
Table 4-24
Data Characteristics of KDCA Meteorological Data
Distance from Proposed
Mattawoman Energy Center
Approximately 24 km
Average Wind Speed
7.75 knots
Pct. Calm Hours
2.13%
Data Completeness
99.72%
AERMET was run using EPA recommended settings to produce the
meteorological data needed for AERMOD. The AERMET analysis
included the use of both the AERMINUTE and AERSURFACE
preprocessors. The AERMINUTE (version 14337) meteorological data
processor was used to produce wind speed and direction data based on
archived 1-minute ASOS data for KDCA, for input into AERMET Stage 2.
A 0.5 m/s wind speed threshold was applied to the 1-minute ASOS
derived wind speeds in AERMET. The AERSURFACE (version 13016) run
was based on USGS NLCD 1992 land use data. AERSURFACE was
configured assuming 12 wind direction sectors and a monthly temporal
resolution. The following additional settings were used to implement
AERSURFACE:
•
•
•
•
•
•
•
•
•
•
•
•
Center Latitude (decimal degrees): 38.847200
Center Longitude (decimal degrees): -77.034500
Datum: NAD83
Study radius (km) for surface roughness: 1.0
Airport? Y, Continuous snow cover? Variable
Surface moisture? Variable, Arid region? N
Month/Season assignments? Default
Late autumn after frost and harvest, or winter with no snow: 12 1 2
Winter with continuous snow on the ground: Variable
Transitional spring (partial green coverage, short annuals): 3 4 5
Midsummer with lush vegetation: 6 7 8
Autumn with unharvested cropland: 9 10 11
To specify whether continuous snow cover should be assumed for any of
the winter months over the five year modeled period, the month by
month snowfall records available from the Annual Climatological
Summary product available from National Climatic Data Center (NCDC)
MD PPRP
4-70
for KDCA were reviewed. Table 4-25 presents the snowfall data for each
month of the five year modeled period and identifies which months were
selected as representative of continuous snow cover in AERSURFACE.
Table 4-25 KDCA Monthly Snowfall and Maximum Snow Depth (Inches)
Monthly Snowfall and Maximum Snowth Depth (Inches) - KDCA
Month
1
2
3
4
5
6
7
8
9
10
11
12
2009
Snowfall Depth
1.9
1
0.1
0
5.5
4
----------------16.6
16
2010
Snowfall Depth
7.4
6
32.1*
21*
------------------2.1
2
2011
2012
Snowfall DepthSnowfall Depth
7.3
4
1.7
1
0.5
2
0.3
0
0.2
-------------------------------------0.2
0
2013
Snowfall Depth
0.9
0
0.4
0
1.6
1
----------------1.5
0
* - Continuous snow cover option in AERSURFACE selected
The surface moisture indicator in AERSURFACE (a choice of wet, dry, or
average) was determined on a month by month basis per EPA guidance
(EPA, 2008). The guidance suggests that the 30-year rainfall record be
examined, and the period in question be compared to the 30 year record to
determine the appropriate moisture description. Dry moisture is assumed
if the month is in the lower 30th percentile of that particular month over
the 30 year record. Similarly, average moisture is assumed for the 30th to
70th percentile, and wet moisture is assumed for the 70th percentile and
greater. The percentile values for each month, and an indication of
whether the month fell in the dry, average or wet categories in presented
in Table 4-26.
MD PPRP
4-71
Table 4-26 KDCA Monthly Surface Moisture Assignments
Month
2009
January
53.3%
February
0.0%
March
16.6%
April
86.6%
May
96.6%
June
83.3%
July
3.3%
August
43.3%
September 43.3%
October
83.3%
November 66.6%
December 100.0%
4.4.3.2.3
2010
10.0%
70.0%
50.0%
6.6%
26.6%
23.3%
76.6%
50.0%
73.3%
50.0%
36.6%
23.3%
2011
30.0%
33.3%
76.6%
56.6%
13.3%
16.6%
36.6%
100.0%
96.6%
60.0%
30.0%
80.0%
2012
23.3%
50.0%
6.6%
20.0%
46.6%
40.0%
30.0%
56.6%
63.3%
86.6%
3.3%
53.3%
2013
46.6%
66.6%
33.3%
46.6%
33.3%
96.6%
70.0%
16.6%
13.3%
90.0%
46.6%
93.3%
Dry
Average
Wet
Receptor Grid
Mattawoman utilized the AERMAP terrain processor to develop elevation
and critical hill elevations for each receptor used in the air quality
modeling analyses. Mattawoman utilized National Elevation Dataset
(NED) data as the source of input elevation data. The receptor grid
developed by Mattawoman is as follows:
•
25-meter spacing around the facility fence line;
•
100-meter spacing from the fence line out to 2-km from the facility;
•
500-meter spacing from 2-km to 5-km from the facility; and
•
1000-meter spacing from 5-km to 25-km of the facility.
The receptor grid utilized by Mattawoman is sufficient to determine
maximum predicted impacts from AERMOD. However, PPRP and MDEARMA have also compiled a receptor grid to use in verification runs for
the Mattawoman project. This receptor grid was constructed as follows:
•
25-meter spacing around the facility fence line and out to 500-m;
•
100-meter spacing from 500-m to 2-km from the facility;
•
500-meter spacing from 2-km to 5-km from the facility; and
•
1000-meter spacing from 5-km to 25-km from the facility.
PPRP utilized this receptor grid to aid in the verification of the modeling
analyses during the review of the CPCN application. PPRP and MDE-
MD PPRP
4-72
ARMA also utilized AERMAP, with NED terrain data as the source of
elevations in this analysis.
4.4.3.2.4
Treatment of NO2 in AERMOD
Mattawoman has relied on the EPA recommended Ambient Ratio Method
(ARM) for evaluating concentrations of NO2 from emissions of NOX in
AERMOD. This method is referred to as the EPA Tier II NO2 modeling
approach. The Tier II assumption is that 80% of emitted NOX converts to
NO2 in the atmosphere for the 1-hr averaging period, and 75% of emitted
NOX converts to NO2 in the atmosphere for the annual averaging period.
The Tier II method is a refinement over the Tier I method, which
conservatively assumes % NOX to NO2 conversion. PPRP and MDEARMA approve of Mattawoman’s use of the recommended ARM method.
4.4.3.2.5
Mattawoman Source Characteristics, Load Analyses, and Intermittent
Emissions
The Project related sources of emissions and their stack characteristics
used by Mattawoman are presented in Table 4-27.
MD PPRP
4-73
Table 4-27
Stack Characteristics Defined by Mattawoman
UTM Coordinates
m
m
Description
Combustion Turbine 1
340028.43 4284212
Combustion Turbine 2
340005.32 4284172
Auxilliary Boiler
339997.54 4284153
Fuel Gas Heater
340105.94 4284176
Emergency Generator
339907.67 4284186
Emergency Fire Water Pump 340000.38 4284068
Cooling Tower Cell 1
340084.1 4284148
340096.71 4284141
340075.78 4284134
340088.59 4284126
340067.41 4284120
340080.16 4284112
340059.12 4284105
340071.93 4284098
340050.95 4284091
340063.5 4284084
340042.58 4284077
340055.17 4284070
Base
Elevation
m
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
70.104
Stack
Height
m
30.48
30.48
30.48
11.89
3.66
2.56
15.8
15.8
15.8
15.8
15.8
15.8
15.8
15.8
15.8
15.8
15.8
15.8
Stack
Diameter
m
5.64
5.64
0.81
0.86
0.2
0.15
10.85
10.85
10.85
10.85
10.85
10.85
10.85
10.85
10.85
10.85
10.85
10.85
Mattawoman characterized the normal operation of the two CTs with 14
different operating scenarios, with loads ranging from 40% to 100%, with
and without the use of duct burners.
In addition to the normal operating scenarios for the CTs, Mattawoman
also addressed warm startups in their modeling analysis. The full
emission rates of NOX and CO for a “warm start” condition were modeled
for the 1-hr CO and 1-hr NOX averaging periods. Mattawoman did not
model the cold start scenario. The cold start scenario will only occur 10
times per year or less for each CT. Despite this, PPRP and MDE-ARMA
have included the cold start scenario in the verification air quality
modeling analyses, as well as hot starts and shutdowns.
Mattawoman also included the emergency equipment in the modeling
analyses, except for the 1-hr NO2 and 1-hr and 8-hr CO. PPRP and MDEARMA have requested that Mattawoman include the emergency
equipment in the 1-hr and 8-hr CO runs, and have included this in their
verification runs. Modeled emission rates and stack parameters used by
MD PPRP
4-74
PPRP and MDE-ARMA for the fourteen different operating scenarios are
shown in Table 4-28.
Table 4-28
Emissions Parameters for Mattawoman Sources Used in PPRP and MDEARMA’s Modeling Analysis
CT
Load
(%)
100
100
75
40
100
100
100
75
40
100
100
100
75
45
Source
CTs Case1
CTs Case2
CTs Case3
CTs Case4
CTs Case5
CTs Case6
CTs Case7
CTs Case8
CTs Case9
CTs Case10
CTs Case11
CTs Case12
CTs Case13
CTs Case14
CT Cold Startup1,2
CT Warm Startup1,3
CT Hot Start1,4
CT Hot Start and Shutdown
CT Shutdown1,5
AUXBLR
FGHTR
COOL 1-12
EGEN7
1,6
Emissions (g/s)
NO2
CO
PM10
24-hr
Annual
8-hr
1-hr
Annual 1-hr
3.14
2.85
1.92
1.92
2.26
1.58
3.79
3.45
2.32
2.32
3.49
2.44
1.23
2.47
2.24
1.51
1.51
1.76
1.00
1.00
1.44
1.01
1.63
1.47
1.71
1.71
2.07
1.45
2.82
2.57
2.66
1.79
1.79
2.09
1.46
2.92
3.59
3.26
2.19
2.19
3.39
2.37
2.24
2.04
1.37
1.37
1.68
1.17
0.91
0.91
1.44
1.01
1.49
1.35
2.37
1.60
1.60
1.93
1.35
2.61
2.80
2.55
1.70
1.70
1.98
1.39
2.32
3.49
3.18
2.12
2.12
3.31
2.08
1.89
1.27
1.27
1.59
1.11
1.49
1.35
0.91
0.91
1.44
1.01
223.7
19.97
29.99
3.42
17.2
184.43
25.08
3.42
-
24-hr
2.26
3.49
1.76
1.44
2.07
2.09
3.39
1.68
1.44
1.93
1.98
3.31
1.59
1.44
3.42
3.42
PM2.5
Annual
1.58
2.44
1.23
1.01
1.45
1.46
2.37
1.17
1.01
1.35
1.39
2.32
1.11
1.01
-
Stack Exit
Exit
T
Velocity
(K)
(m/s)
358.15
28.07
357.04
28.22
353.71
22.25
352.59
16.12
359.82
26.85
359.26
27.13
357.59
27.22
354.82
21.31
353.15
15.42
25.30
360.93
360.93
26.24
358.15
26.27
357.04
20.57
355.93
15.82
16.34
348.87
355.85
26.81
356.64
27.76
348.54
18.23
355.98
26.98
356.68
27.81
14.11
5.87
0.053
0.060
-
0.053
0.060
-
153.76
21.47
0.202
0.037
-
44.97
0.202
0.037
-
3.33
0.039
0.013
0.007
0.039
0.013
0.007
3.33
0.039
0.013
4.52E-05
0.039
0.013
4.52E-05
346.48
354.84
356.30
353.71
477.59
699.82
305.37
16.76
25.33
27.26
15.24
9.94
6.46
6.37
-
0.016
1.08
0.13
0.003
8.03E-04
0.003
8.03E-04
749.82
109.73
0.002
0.22
0.028 6.00E-04 1.64E-04 6.00E-04
1.64E-04
789.26
36.21
EFWP7
1
- Durations of the startup and shutdown operations for the CTs are as follows: Cold Startup: 49 minutes, Warm Startup: 51 minutes, Hot
Startup: 46 minutes, Shutdown: 13 minutes.
2
- Emissions for the Cold Startup scenario reflect 153 lb of NOX, 1772 lb of CO, and 9.4 lb of PM10/PM2.5 for the cold startup added to the
worst case normal operation scenario (Case 2) emission rates of 30.1 lb/hr of NOX, 18.4 lb/hr of CO, and 27.7 lb/hr of PM10/PM2.5 for the
remainder of the averaging period duration where the CTs are operating normally.
3
- Emissions for the Warm Startup scenario reflect 132 lb of NOX, 1461 lb of CO, and 10.8 lb of PM10/PM2.5 for the warm startup added to
the worst case normal operation scenario (Case 2) emission rates of 30.1 lb/hr of NOX, 18.4 lb/hr of CO, and 27.7 lb/hr of PM10/PM2.5 for
the remainder of the averaging period duration where the CTs are operating normally.
4
- Emissions for the Hot Startup scenario reflect 105 lb of NOX, 1216 lb of CO, and 9.9 lb of PM10/PM2.5 for the hot startup added to the
worst case normal operation scenario (Case 2) emission rates of 30.1 lb/hr of NOX, 18.4 lb/hr of CO, and 27.7 lb/hr of PM10/PM2.5 for the
5
- Emissions for the Shutdown scenario reflect 23 lb of NOX, 156 lb of CO, and 2.5 lb of PM10/PM2.5 for the shutdown added to the worst
case normal operation scenario (Case 2) emission rates of 30.1 lb/hr of NOX, 18.4 lb/hr of CO, and 27.7 lb/hr of PM10/PM2.5 for the
6
- The hot start and shutdown scenario includes 2 hot starts and 2 shutdowns within the averaging period time. Emission rates and stack
parameters are blended with the worst case normal operation scenario (Case 2).
7
- Emergency equipment is assumed to operate for 1 of 8 hours for the 8-hr runs, 1 hr/day for the 24-hr runs, and 100 hrs/yr for the annual
runs.
MD PPRP
4-75
4.4.3.2.6
Building Downwash
Mattawoman used the Building Input Profile Program (BPIP, version
04274) to develop the parameters necessary to account for the effects of
building downwash on the modeled sources. It should be noted that no
sources in the modeling analysis are proposed with stack heights that
exceed the Good Engineering Practice (GEP) stack height. For new
sources, the GEP stack height is defined as the greater of 65 m or the
“formula height” calculated by BPIP. No formula heights in the BPIP
analysis exceeded 65 m, and all stacks are proposed at heights of less than
65 m. PPRP and MDE-ARMA conclude that Mattawoman has correctly
applied the downwash parameters necessary for use in AERMOD, and
have satisfied GEP stack requirements. The building and stack layout
proposed by Mattawoman is shown in Figure 4-3 below.
Figure 4-3
4.4.3.2.7
Background Pollutant Concentrations
Mattawoman has included representative background values of NO2 for
the 1-hr averaging period for use in the NAAQS analyses. The 1-hr NO2
value is based on monitoring data from the James S. Long Park
MD PPRP
4-76
monitoring station in Prince William County, VA. Details of the 1-hr NO2
background value are provided in Table 4-29.
The PM2.5 24-hr and annual averaging period background values used in
the NAAQS analysis are based on monitoring data from the Prince
George’s Equestrian Center monitoring station in Prince George’s County,
MD. The background PM2.5 values identified are shown in Table 4-29.
PPRP and MDE-ARMA have also identified a conservative representative
background value for 1-hr CO to be used in the cumulative modeling
analysis. The background value for 1-hr CO concentrations is taken from
the Alexandria City, VA monitoring station. The design value for this
monitor is provided in Table 4-29 below.
Table 4-29
Background Monitor Concentrations
Averaging
Period
Pollutant
Monitor ID
NO2
1-hr
51-153-0009 James S. Long Park
PM2.5
24-hr
24-033-8003
PM2.5
Annual
CO
1-hr
Location Name
Prince George's
Equestrian Center
Prince George's
24-033-8003
Equestrian Center
51-510-0021 Alexandria
Monitor
Distance to
County, State
Site (km)
Prince William
71.4
County, VA.
Prince George's
15.8
County, MD.
Prince George's
15.8
County, MD.
Alexandria City,
25
VA.
Background
Value
Design Value
3
Basis
(µg/m )
2011-2013
52
Design Value
2011-2013
21
Design Value
2011-2013
8.2
Design Value
2013 Design
5610.5
Value
PPRP and MDE-ARMA note that the Prince William County, VA monitor
has been previously recommended for use to represent background NO2
concentrations for other recent CPCN applications in rural southeast
Maryland. This monitor is located away from localized sources of NOX
emissions (due in large part to heavily congested traffic) that occur at
monitoring stations located closer to the Washington, DC and Baltimore,
MD, metropolitan areas. PPRP and MDE-ARMA agree that the Prince
William County, VA NO2 monitor is adequately representative of
background NO2 concentrations in rural Prince George’s County.
In January 2013, the Significant Monitoring Concentrations (SMCs) for
PM2.5 were vacated by the DC Circuit Court. The SMCs are
concentrations that are used to determine if a project subject to PSD
regulations needs to consider preconstruction ambient monitoring to
determine existing air quality conditions at the project site.
Preconstruction monitoring is typically required when a project’s modeled
impacts exceed the SMCs and the existing air quality monitoring network
in the region is inadequate to characterize existing air quality. Since there
is no SMC for PM2.5, it is critical to establish that representative PM2.5
MD PPRP
4-77
baseline air quality data for the region are available. The greater
Washington DC, VA, MD area has ten PM2.5 monitors across the region.
The closest monitor to the proposed Mattawoman Project is the Prince
George’s Equestrian Center monitor. This monitor is situated in a semirural area, removed from the suburban Washington DC area, similar to
the project setting. PPRP and MDE-ARMA believe the Prince George’s
Equestrian Center monitor is adequately representative of existing PM2.5
air quality in Prince George’s County, and therefore satisfies the
requirement to establish baseline air quality data for PSD permitting
purposes.
4.4.3.2.8
PM2.5 Secondary Formation
Mattawoman’s air quality modeling analysis addressed the formation of
secondary PM2.5 due to emissions of precursors from the Project. PM2.5
precursor emissions are NOX, SO2, and Ammonia. MDE’s May 2013
Maintenance Plan 11 for the 1997 PM2.5 NAAQS addressed Ammonia’s
role in the formation of PM2.5 in the Washington, DC, VA, MD PM2.5
nonattainment area. Specifically, as stated in the plan, it was determined
that ammonia does not play a significant role in the formation of PM2.5 in
this region, therefore, ammonia was not addressed as a PM2.5 precursor
in the air quality modeling analysis. Consequently, the secondary PM2.5
analysis focused on emissions of NOX and SO2 from the proposed Project
as precursors for PM2.5.
The first step to addressing the potential formation of secondarily formed
PM2.5 due to the Project emissions is to qualitatively assess the Project’s
emissions compared to known levels of related PM2.5 species in the
region. Speciated PM2.5 data have been compiled by EPA for the 2012
design values across the country. The speciated data for the Prince
George’s Equestrian Center PM2.5 monitor are presented in Figure 4-4.
These data were acquired from EPA’s SANDWICHed PM2.5 speciation
database. 12
11 Washington DC-MD-VA 1997 PM
– May 22, 2013
2.5
Maintenance Plan – Metropolitan Council of Governments
12 http://www.epa.gov/pmdesignations/2012standards/techinfo.htm
MD PPRP
4-78
Figure 4-4
Speciation of Annual PM2.5 Concentration – 2012 PM2.5
Design Value – Prince George’s Equestrian Center Monitor
Figure 4-4 shows that particulate nitrate plays a relatively insignificant
role in the total PM2.5 concentration at the monitor (only 5% of the total
annual PM2.5 concentration), while particulate sulfate is dominant. The
proposed Project has significant emissions of NOX with respect to PSD,
whereas the emissions of SO2 are insignificant and not subject to PSD
review. Since particulate nitrate plays a minor role in the formation of
PM2.5 in this region, it can be concluded that the proposed Project, with
major emissions of NOX would be unlikely to significantly contribute to
secondary PM2.5.
Although the PM2.5 speciation profile for the region indicates that the
formation of significant secondary PM2.5 due to emissions from the
Project is not likely, the emissions of NOX due to the project (242.1
tons/yr) are well in excess of the PSD Significant Emission Rate (SER),
and therefore additional analyses should be conducted to ensure that the
formation of secondary PM2.5 could not possibly endanger the PM2.5
NAAQS or PSD increment. Mattawoman has proposed a semi-qualitative
analysis to address secondary PM2.5 formation. Specifically, the approach
specified by the National Association of Clean Air Agencies (NACAA) in
their January 2011 report was utilized, with conservative assumptions
selected.
The NACAA approach for secondary formation of PM2.5 is to apply
pollutant offset ratios between PM2.5 and PM2.5 precursors.
Mattawoman utilized the worst-case ratios cited by NACAA in their
MD PPRP
4-79
analysis, 15:1 SO2 to PM2.5 and 77:1 NOX to PM2.5. These ratios are used
to calculate an equivalent primary PM2.5 ratio, a factor that will be
applied to the Project-related emissions of direct PM2.5 to account for the
effect of additional PM2.5 from secondary formation. The methodology
used to calculate the appropriate ratio is presented in Table 4-30 (NACAA,
2011).
Table 4-30
NACAA PM2.5 Ratio Calculation Methodology
Keys Energy Center
Mattawoman Energy
(Proposed Project, Not
CPV St. Charles (Proposed
Primary PM2.5 Emissions
SO2 Emissions
Units
tons/yr
tons/yr
Center
172.3
39.2
Constructed)
94.5
10.7
Project, Not Constructed)
99.9
12.2
NOX Emissions
tons/yr
242.1
157.1
145.5
NACAA Worst Case Pollutant Ratios:
15 tons SO2 /ton Primary PM2.5
77 tons NOX/ton Primary PM2.5
Secondary PM2.5 due to
SO2 1 tons/yr
Secondary PM2.5 due to
2.61
0.71
0.81
NOX1 tons/yr
3.14
2.04
1.89
5.76
2.75
2.70
178.06
97.25
102.60
1.033
1.029
1.027
Total Secondary PM2.5
tons/yr
Total Project Related PM2.5 tons/yr
(Primary + Secondary)
Primary PM2.5 Multiplier
(Total PM2.5/Primary
PM2.5)
1
Secondary PM2.5 Calculation Example: 39.2 tpy SO2 x 1 tpy PM2.5/15 tpy SO2 = 2.61 tpy Secondary PM2.5
As shown in Table 4-30, contribution to PM2.5 formation due to SO2
precursors was assumed to potentially occur due to the proposed Project,
but also two additional proposed major sources that have yet to be
constructed. For the purposes of this analysis, it is assumed that the
existing PM2.5 background concentrations measured at the Prince
George’s PM2.5 monitor already inherently account for the contribution of
existing NOX and SO2 sources in the region with respect to PM2.5
formation. The primary PM2.5 multiplier values presented in Table 4-30
were applied to the maximum modeled 24-hr and annual concentrations
from each of the facilities, and conservatively paired with the maximum
overall model design values for primary PM2.5. More detail on the
background sources considered in the cumulative air quality modeling
analyses is presented in the following section of the ERD.
MD PPRP
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4.4.3.2.9
Modeling Background Source Inventory
Mattawoman compiled a detailed and comprehensive background
inventory for use in the 1-hr NO2, 24-hr PM2.5, and annual PM2.5
cumulative air quality modeling analyses, based on modeling inventory
data received from MDE. Mattawoman developed the appropriate short
or long term emission rates for each facility included in the cumulative
analysis. All facilities that could potentially emit greater than 100 tpy
NOX located within 30 km of the Project Site were included in the NOX
cumulative analysis. Mattawoman provided a detailed discussion in the
air quality modeling protocol that described the sources that were
included in as well as excluded from the cumulative analysis.
PPRP and MDE-ARMA believe the background NO2 inventory, while
comprehensive and thorough, is unrealistically conservative for use in a
modeling analysis for the 1-hr NO2 NAAQS. EPA guidance on air quality
modeling for the 1-hr NO2 NAAQS suggests that “…sources to include in
the [cumulative 1-hr NO2] modeling analysis should focus on the area
within about 10 kilometers of the project location in most cases” (EPA,
2011). Since the proposed Project site is not situated in a setting with
significant complex terrain, PPRP and MDE-ARMA feel the EPA guidance
should be considered. Therefore, PPRP and MDE-ARMA have limited the
background inventory to sources identified by Mattawoman within 10 km
of the Project site, with the exception of those sources outside 10 km,
which are known by PPRP and MDE-ARMA to be nearly continuous in
operation and also significant contributors to the overall emissions of NOX
in the region from stationary sources, namely existing and proposed
power plant sources. The background NOX source selected by PPRP and
MDE-ARMA are shown in Table 4-31.
MD PPRP
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Table 4-31
Offsite NOX Facilities Modeled by PPRP and MDE-ARMA
Model ID
Facility
MD22-MD29 Chalk Point Generating Station
Panda Brandywine Generating
MD32
Station
Proposed CPV St. Charles
MD36-MD37 Generating Station
MD38-MD40 Proposed Keys Energy Center
MD47
Thomas Stone High School
MD48
Southern Maryland Hospital
Distance to
Mattawoman
(km)
Emissions (lb/hr)
18.56
3,322.2
3.65
512.0
14.22
1.62
9.49
7.07
39.5
44.7
34.1
24.0
Modeled NO X
The PM2.5 cumulative modeling inventory focused on the area within 10km of the proposed Project, as proposed in the PM2.5 air quality modeling
protocol. This area was determined through consultation with PPRP and
MDE-ARMA, and is believed to be consistent with EPA air quality
modeling guidance for PM2.5 (EPA, 2014), which stresses the
appropriateness of professional judgment and cautions against the
uncritical application of past guidance in compiling cumulative modeling
inventories, notably the recommendations found in EPA’s draft 1990 New
Source Review Workshop Manual. Major sources of PM2.5 outside of 10
km from the Project were also included, similar to the approach used to
develop the 1-hr NO2 cumulative inventory. Similar to the 1-hr NO2
cumulative modeling inventory, the PM2.5 cumulative inventory includes
two proposed facilities within 20 km of the Project Site that are proposed
and not yet constructed. The complete offsite inventory modeled for
PM2.5 is displayed below in Table 4-32.
Table 4-32
ARMA
Model ID
KEYS
BRANDY
KIRBY
CPV
CHALK
Offsite PM2.5 Facilities Modeled by PPRP and MDEDistance to
Mattawoman
Facility
(km)
Proposed Keys Energy Center
1.62
Panda Brandywine Generating Station
3.65
Aggregate Industries - Kirby Road Asphalt Plant
11.5
Proposed CPV St. Charles Generating Station
14.22
Chalk Point Generating Station
18.56
Modeled PM2.5
Emissions (lb/hr)
30.8
60.0
4.7
48.3
915.9
A background inventory for CO was also created by PPRP and MDEARMA for use in the cumulative modeling. As presented in the following
section of the ERD, the 1-hr CO SIL was exceeded for the combustion
turbine cold startup case. Mattawoman has not provided a cumulative
MD PPRP
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modeling analysis of 1-hr CO impacts due to this modeled SIL
exceedance, citing the infrequent nature of cold startups (eight per year,
per turbine), and the low probability that a worst case cold startup
operation would occur during meteorological conditions that would cause
a modeled exceedance of the SIL. Although PPRP and MDE-ARMA agree
that the cold startups would in reality be very unlikely to endanger the 1hr CO NAAQS, an independent verification of 1-hr CO NAAQS
compliance was conducted to ensure that no modeled violations of the 1hr CO NAAQS would be possible. An inventory of nearby sources of CO,
namely the existing Panda Brandywine station and the proposed Keys
Energy Center was compiled for use in the 1-hr CO NAAQS analysis for
the cold startup scenario, as shown in Table 4-33.
Table 4-33
Model ID
KEYS
BRAN
Offsite CO Facilities Modeled by PPRP and MDE-ARMA
Facility
Proposed Keys Energy Center
Panda Brandywine Generating Station
4.4.3.3
Air Quality Modeling Analysis Results
4.4.3.3.1
Class II Significance Analysis
Distance to
Mattawoman
(km)
1.62
3.65
Modeled CO
Emissions (lb/hr)
33.4
1710.0
The first step of PSD air quality modeling analysis is to establish which
pollutants that have triggered PSD review have modeled concentrations in
excess of established SILs. The results of the SIL analyses provided by
Mattawoman are presented in Table 4-34 below.
MD PPRP
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Table 4-34
Summary of Class II SIL Analysis Conducted by
Mattawoman
Pollutant
PM2.5
PM10
NO2
Warm Startup
CO
Warm Startup
Averaging
Period
24-hour
Annual
24-hour
Annual
1-hour
Annual
1-hour
1-hour
8-hour
1-hour
Class II SIL
Maximum
Modeled
Concentration
µg/m3
1.2
0.3
5
1
7.5
1
7.5
2000
500
2000
µg/m3
2.60
0.22
3.60
0.34
10.0
0.38
96.9
15.6
6.60
1971
The results of the modeling analyses provided by Mattawoman indicate
that maximum modeled 1-hr NO2 and 24-hr PM2.5 concentrations exceed
the SIL. Therefore, 1-hr NO2 and 24-hr PM2.5 NAAQS analyses were
conducted. A cumulative annual PM2.5 analysis was also conducted to
ensure compliance with the annual PM2.5 NAAQS and PSD increment,
since secondary impacts of PM2.5 are also being considered as part of this
analysis. The results of the verification analyses conducted by PPRP and
MDE-ARMA for the SILs are presented in Table 4-35 below. These results
show that the maximum 1-hr CO concentration also exceeds the SIL, and
so a NAAQS analysis should be conducted.
MD PPRP
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Table 4-35
Summary of Class II SIL Analysis Conducted by PPRP and
MDE-ARMA
24-hour
Annual
µg/m3
1.2
0.3
Maximum
Modeled
Concentration
µg/m3
2.63
0.21
Cold Startup1
24-hour
1.2
2.15
1
24-hour
1.2
2.12
24-hour
1.2
2.14
24-hour
Annual
5
1
3.06
0.28
Cold Startup1
24-hour
5
2.39
1
24-hour
5
2.39
24-hour
5
2.39
1-hour
Annual
7.5
1
11.24
0.43
Cold Startup2
Warm Startup
1-hour
7.5
1-hour
7.5
122.00
87.1
Hot Startup
2
1-hour
7.5
83.6
Shutdown
2
1-hour
7.5
41.4
1-hour
8-hour
2000
500
714.7
26.8
Cold Startup2
1-hour
2000
3019.2
Warm Startup
2
1-hour
2000
2293.6
Hot Startup
2
1-hour
2000
2053.6
Shutdown
2
1-hour
2000
714.7
1
8-hour
500
70.1
8-hour
500
58.5
8-hour
500
114.4
Averaging
Period
Pollutant
PM2.5
Warm Startup
Hot Startup &
Shutdown1,3
PM10
Warm Startup
Hot Startup &
Shutdown1,3
NO2
CO
Cold Startup
Warm Startup1
Hot Startup &
Shutdown1,3
Class II SIL
1
- 8-hr and 24-hr Startup/Shutdown scenarios were modeled with blended emission
rates and stack parameters. The startup/shutdown emission rates, stack exit velocities
and stack exit temperatures were blended with the worst case normal operation
scenario (Case 2) for the respective averaging period.
2
- 1-hr Startup/Shutdown scenarios were modeled with blended emission rates. The
startup/shutdown emission rates were blended with the worst case normal operation
scenario (Case 2) for the 1-hr period.
3
- The hot start and shutdown scenario includes 2 hot starts and 2 shutdowns within
the averaging period time. Emission rates and stack parameters are blended with the
worst case normal operation scenario (Case 2).
MD PPRP
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4.4.3.3.2
NAAQS and Increment Analysis
A NAAQS analysis was conducted for NO2 for the 1-hr averaging period
and for PM2.5 for the annual and 24-hr averaging periods to demonstrate
compliance with their respective NAAQS. The results of Mattawoman’s
analysis are provided in Table 4-36. It should be noted that there is no
PSD increment for 1-hr NO2. The warm start scenario was modeled for
the 1-hr NO2 scenario, while Case 9 was modeled for the 24-hr PM2.5
scenario and Case 12 was modeled for the annual PM2.5 scenario to
demonstrate compliance with the NAAQS and PSD increment, since the
SIL modeling analyses indicated that these scenarios had the largest
impacts on concentrations.
Table 4-36
Summary of NAAQS Analysis Conducted by Mattawoman
Maximum
Modeled
Background
Concentration Concentration
Scenario
NO2 1-hr
μg/m3
μg/m3
Secondary
PM2.5
Emissions*
Total
Concentration NAAQS
μg/m3
μg/m3
μg/m3
Maximum Mattawoman
Contribution to any
NAAQS Exceedance
μg/m3
4,532
52
-
4584
188
4.5
PM2.5 24-hr
1.4
21
0.040
22.48
35
N/A
PM2.5 Annual
0.4
8.2
0.007
8.56
12
N/A
*Secondary PM2.5 emissions are due to SO2 and NOX emissions from Mattawoman, CPV and Keys
Mattawoman also conducted an increment analysis for 24-hr and annual
PM2.5. The results of this analysis are provided in Table 4-37 below.
Table 4-37
Summary of Increment Analysis Conducted by Mattawoman
Secondary
Emissions**
Total
Concentration
Allowable
Increment
Maximum Mattawoman
Contribution to any
Increment Exceedance
μg/m3
μg/m3
μg/m3
μg/m3
2.35
0.077
2.42
9
N/A
0.296
0.009
0.31
4
N/A
Modeled
Concentration
μg/m3
PM2.5 24-hr*
PM2.5 Annual
Scenario
PM2.5
* Highest 2nd Highest
** Secondary PM2.5 emissions are due to SO2 and NOX emissions from Mattawoman, CPV and Keys
PPRP and MDE-ARMA conducted verification analyses of the NAAQS
and increment analyses provided by Mattawoman, as well as a NAAQS
analysis for 1-hr CO. The verification run for 1-hr NO2 only considered
receptors where the proposed Project caused a modeled concentration in
excess of the SIL, while the PM2.5 and CO verification runs included all
receptors. The results of the PPRP and MDE-ARMA verification of the
NAAQS and increment analyses are presented below in Table 4-38 and
Table 4-39.
MD PPRP
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Table 4-38
Summary of NAAQS Analysis Conducted by PPRP and MDEARMA
Maximum
Modeled
Background
Concentration Concentration
Scenario
Secondary
PM2.5
Emissions*
Total
Concentration NAAQS
Maximum Mattawoman
Contribution to any
NAAQS Exceedance
μg/m3
μg/m3
μg/m3
μg/m3
μg/m3
μg/m3
NO2 1-hr Case 4
128.2
52
-
180.2
188
N/A
NO2 1-hr Case 12
128.2
52
-
180.2
188
N/A
NO2 1-hr Cold Start
128.2
52
-
180.2
188
N/A
NO2 1-hr Hot Start
128.2
52
-
180.2
188
N/A
NO2 1-hr Shutdown
128.2
52
-
180.2
188
N/A
NO2 1-hr Warm Start
128.2
52
-
180.2
188
N/A
PM2.5 24-hr Case 9
3.9
21
0.092
25.0
35
N/A
PM2.5 24-hr Case 12
3.9
21
0.090
25.0
35
N/A
PM2.5 24-hr Cold Start
3.9
21
0.089
25.0
35
N/A
PM2.5 24-hr
Hot Start/Shutdown
3.9
21
0.089
25.0
35
N/A
PM2.5 24-hr Warm Start
3.9
21
0.089
25.0
35
N/A
PM2.5 Annual (Case 9)
0.6
8.2
0.014
8.8
12
N/A
3047.3
2081.7
2293.7
5610.5
5610.5
5610.5
-
8657.8
7692.2
7904.2
40000
40000
40000
N/A
N/A
N/A
CO 1-hr Cold Start
CO 1-hr Hot Start
CO 1-hr Warm Start
*Secondary PM2.5 emissions are due to SO2 and NOX emissions from Mattawoman, CPV and Keys
Table 4-39
Scenario
Summary of Increment Analysis Conducted by PPRP and MDEARMA
Modeled
Concentration
Secondary
PM2.5
Emissions**
Total
Concentration
Allowable
Increment
Maximum Mattawoman
Contribution to any
Increment Exceedance
μg/m3
μg/m3
μg/m3
μg/m3
μg/m3
PM2.5 24-hr*
5.00
0.15
5.15
9
N/A
PM2.5 Annual
0.71
0.02
0.73
4
N/A
* Highest 2nd Highest
**Secondary PM2.5 emissions are due to SO2 and NOX emissions from Mattawoman, CPV and Keys
In both the Mattawoman analysis and the PPRP analyses, the proposed
Project does not contribute to any exceedance of the 1-hr NO2 or the 24-hr
PM2.5 NAAQS. The PPRP analysis also shows that the Project does not
contribute to any exceedance of the 1-hr CO NAAQS. The allowable
increment for 24-hr and annual PM2.5 is also not exceeded. Since the
proposed Project does not contribute to any modeled NAAQS exceedance,
the conclusion of the analysis is that the proposed Project will not
endanger the applicable NAAQS and PSD increments.
MD PPRP
4-87
Due to the less conservative approach used to select sources for the
background NOX modeling inventory, results from PPRP and MDEARMA do not show the excessive concentrations found in the
Mattawoman analysis. The nature of the background inventory
developed by Mattawoman and used in their 1-hr NO2 NAAQS analysis
caused large modeled predictions due to various smaller NOX sources,
often due to conservative assumptions made by Mattawoman (e.g.,
assuming daily emissions are equivalent to hourly emissions) using the
data provided by MDE. As stated previously, PPRP and MDE-ARMA
revised the background modeling inventory to include only those sources
within 10 km of the Project Site and other regional power plant sources
outside of 10 km from the Project Site.
4.4.3.3.3
Class I Significance Analysis
The proposed Project is located within 300 km of five federally protected
Class I areas. These areas are listed below, with the distance from
Mattawoman noted:
•
Dolly Sods Wilderness Area – 218.5 km
•
Otter Creek Wilderness Area – 241.5 km
•
Shenandoah National Park – 115.7 km
•
James River Face Wilderness Area – 255.5 km
•
Brigantine Wilderness Refuge – 227.3 km
The Federal Land Managers (FLMs) have adopted a threshold for new
sources of air pollution to use to assist in the determination of whether an
analysis of air quality related values (AQRVs) such as deposition and
visibility impacts should be required for Class I areas. This threshold is
referred to as the Q/D ratio, where Q is the total emissions of NOX, SO2,
PM, and Sulfuric Acid from the proposed project in tons, and D is the
distance to the Class I area of concern in km. A Q/D ratio of less than 10
generally indicates that a project is unlikely to adversely affect AQRVs in
the Class I area. The highest Q/D ratio for the proposed Project is 5.7.
PPRP and MDE-ARMA agree that an AQRV analysis should not be
required for the proposed Project.
Although an AQRV analysis is not required for the proposed Project,
Mattawoman has completed an analysis to demonstrate that the proposed
Project emissions will have a minimal impact in relation to Class I PSD
increments by demonstrating impacts less than the Class I SILs for NO2,
MD PPRP
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PM10 and PM2.5. Mattawoman used CALPUFF version 5.8 and
CALPOST version 6.221 along with meteorological data from the VISTAS
Domain 5 CALMET data set, for 2001, 2002, and 2003 to assess compliance
with the Class I SILs for NO2 and PM2.5. PPRP and MDE-ARMA agree
that the use of CALPUFF along with VISTAS Domain 5 meteorological
data represents best practice for Class I area analyses for sources in
Maryland. Mattawoman’s results of the Class I analysis are summarized
in Table 4-40. PPRP and MDE-ARMA confirmed that none of the receptors
in Class I areas exceeded the applicable Class I SILs.
Table 4-40
Pollutant
Summary of Class I Analysis Conducted by Mattawoman
2001 Maximum 2002 Maximum 2003 Maximum
Modeled
Modeled
Modeled
Class
I
SIL
Averaging
Concentration Concentration Concentration
Period
3
24-hour
Annual
Annual
PM2.5
NO2
4.4.3.3.4
µg/m
0.3
0.2
0.1
3
µg/m
0.0242
0.0013
0.0005
3
µg/m
0.0268
0.0009
0.0005
3
µg/m
0.0583
0.0014
0.0008
Secondary Impacts Analysis
Mattawoman provided a qualitative assessment of the Project’s potential
impacts on growth, soils, vegetation, wildlife, and visibility. PSD
regulations require that projects assess their impact on these media. The
analysis provided by Mattawoman included the following conclusions:
•
Emissions of regulated pollutants from the Project will not be
expected to adversely affect air quality, as evidenced by the air
quality modeling analyses. Therefore, impacts on soils vegetation,
and wildlife are expected to be minimal since the PSD air quality
modeling analysis, which is based on more stringent human health
standards, demonstrates acceptable impacts.
•
No significant industrial, commercial, or residential growth is
expected due to the Project. The emissions of pollutants due to
construction activity are expected to be minimal and temporary in
nature. Once the facility is operational, it is expected to require
approximately 30 employees, which will not have a substantial
effect on residential growth in the region.
PPRP and MDE-ARMA also note that Mattawoman will be required to
comply with the visible emissions limitation of COMAR 26.11.09.05A,
MD PPRP
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which will help ensure that visible plumes (other than condensed water)
from the Project sources will not adversely impact local visibility.
4.4.3.4
Conclusions
The air quality modeling analyses conducted by Mattawoman in support
of the proposed Project are adequate to demonstrate compliance with
applicable Class I and Class II PSD Increments and NAAQS. The air
quality modeling analyses conducted by Mattawoman have been
independently verified by PPRP and MDE-ARMA. It should be noted
that PPRP and MDE-ARMA also performed additional analyses to ensure
compliance with the 1-hr CO NAAQS. The conclusion of the air quality
modeling analysis is that the scope of the analysis is sufficient to address
air quality with respect to the proposed Project, and the results indicate
that the proposed Project will not adversely impact air quality in the
region.
4.5
NONATTAINMENT NEW SOURCE REVIEW (NA-NSR)
The proposed Project is located in Prince George’s County, which is
designated as a marginal nonattainment area for ozone. NOx and VOCs
are regulated by EPA and MDE as ozone pre-cursor pollutants. Table 4-41
presents a summary of Project potential emissions compared to the
applicability threshold for NA-NSR.
Table 4-41
Pollutants
NANSR Applicability Analysis for the Project
Potential
Emissions
(tpy)
NOX
VOC
220.7
144.1
NANSR
Applicability
Threshold
(tons)
25
25
NANSR
Triggered?
(Yes/No)
Yes
Yes
As identified in Table 4-41, potential NOx and VOC emissions from the
Project are greater than 25 tpy; therefore, the Project triggers the
requirements of the NA-NSR program. Potential emissions from the
Project are presented in Table 4-15.
As a part of NA-NSR for NOx and VOC, Mattawoman is required to
comply with the following:
•
Implement LAER level of pollution control from all Project sources;
MD PPRP
4-90
•
Obtain emissions reductions (offsets) for projected potential emissions;
•
Certify that all other sources in Maryland owned by Mattawoman
comply with all applicable requirements of the Clean Air Act (CAA);
and
•
Demonstrate through an analysis of alternative sites, sizes, production
processes, and environmental control techniques that benefits of the
proposed source significantly outweigh the environmental and social
costs imposed as a result of its location, construction, or modification.
The following sections review the Project in relation to these NA-NSR
requirements.
4.5.1
LAER Evaluation
LAER is defined in COMAR 26.11.17.01(B)(15) as:
(a) … for any emissions unit, the more stringent rate of
emissions based on the following:
(i) The most stringent emissions limitation which is
contained in the implementation plan of any state for the
class or category of stationary source, unless the owner or
operator of the proposed stationary source demonstrates
that these limitations are not achievable; or
(ii) The most stringent emissions limitation which is
achieved in practice by the class or category of stationary
sources, with this limitation, when applied to a modification,
meaning the lowest achievable emissions rate for the new or
modified emissions units within the stationary source.
(b) The application of this definition does not permit a proposed
new or modified emissions unit to emit any pollutant in excess of
the amount allowable under 40 CFR Part 60.
In general, the procedure used to identify and determine LAER
requirements are similar to, but more stringent than, the procedure to
determine BACT requirements (see Section 4.4). For example, in addition
to reviewing available control technologies, all applicable emissions limits
in effect in any State Implementation Plan (SIP) must also be considered as
part of the procedure to determine LAER requirements.
MD PPRP
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PPRP and MDE-ARMA reviewed Mattawoman’s LAER determination
and prepared this analysis with additional information based on review of
recently issued permits and LAER determinations. Mattawoman’s NOx
and VOC LAER evaluations were conducted in accordance with EPA’s
guidance in the draft New Source Review Workshop Manual 13 and applicable
federal and State regulations. The objective of the LAER analyses was to
identify applicable Federal and State of Maryland air regulations and
“achieved in practice” limitations for each piece of proposed equipment
with the potential to emit NOx or VOCs.
of the State considered NOx and VOC LAER emission limits that have
already been established for identical or similar equipment as
documented in the RBLC. The review also included identifying and
assessing other recently issued permits for the construction of new power
generation facilities, which have not yet appeared in the RBLC. NOX and
VOC LAER emission limit background information is provided in
Appendix B.
4.5.1.1
NOX LAER
4.5.1.1.1
Combustion Turbines
PPRP assessed the following control technologies as part of the NOX
LAER evaluation:
•
Selective Catalytic Reduction (SCR);
•
Selective Non-Catalytic Reduction (SNCR);
•
EMXTM/SCONOXTM;
•
Low-NOx (DLN) Combustors;
•
Catalytic Combustion (XONONTM);
•
Water/Steam Injection; and
•
Good Combustion Practices.
Both XONONTM and EMXTM/SCONOXTM were determined to be
technically infeasible. XONONTM is not available for the CTs, and
EMXTM/SCONOXTM has not been demonstrated to operate on larger CTs.
13
EPA 1990
MD PPRP
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In addition, these technologies are not capable of achieving NOx
reductions at the level that SCR can accommodate on CTs.
Of the remaining control technologies that were technically feasible, a
combination of SCR and DLN results in the lowest NOx achievable
emission rate. In the CPCN application, Mattawoman proposes to install
low NOx combustors and a SCR system to reduce NOx emissions from the
CTs/HRSGs. Other potentially available technologies do not provide a
means to reduce NOx emissions to the levels achievable through the use of
SCR and DLN. Therefore, no additional controls were evaluated as a part
of this analysis.
Mattawoman proposes a NOx LAER emission rate for each of the
CTs/HRSGs with and without duct firing of no greater than 2.0 ppmvd at
15% O2, on a 3-hour average basis, except during periods of startup and
shutdown. Based on a review of RBLC database and other permits issued
for combined cycle power generating CTs, the lowest permitted and
demonstrated NOx emission rate was 2.0 ppmvd at % O2.
As a result of our analysis, PPRP and MDE-ARMA agree that the
following meets LAER for the CTs: a NOx emission limit of 2.0 ppmvd at
15% O2, based on a 3-hour block average for normal operation to be
achieved through the use of the use of pipeline natural gas, SCR, and
DLN. This proposed LAER limit applies during normal operation only
(excluding periods of startup and shutdown). Continuous compliance
demonstration requires operation of a NOx CEMS. In addition,
Mattawoman will be required to perform initial and annual stack testing
through the use of Method 7E, or an equivalent test method requiring
MDE approval.
PPRP determined based on a review of other permits and the RBLC
database that post-combustion controls are not considered technically
feasible during startup and shutdown conditions. Therefore, LAER for
natural-gas fired CTs for startup and shutdown emissions is to ensure that
correct procedures are followed to allow for optimal performance during
normal operations, and that the emissions during each startup and
shutdown event will be minimized.
PPRP and MDE-ARMA have determined that the CTs will be subject to
the following limits during startup and shutdown, as provided to
Mattawoman by the manufacturer, Siemens:
MD PPRP
4-93
•
•
•
NOx emissions will be limited to 153 pounds per event for each
cold startup, 132 pounds per event for each warm startup, and 105
pounds per event for each hot startup, as determined by CEMS.
NOx emissions will be limited to 23 pounds per shutdown event, as
determined by CEMS.
The startup and shutdown emissions must also be included in the
facility-wide annual emission limits.
For compliance demonstration, Mattawoman will be required to measure
the emissions from the CTs/HRSGs at all times when the CTs/HRSGs are
operating, including periods of startup and shutdown, using a certified
NOx CEMS. The emissions from startup and shutdown events will be
added to the emissions from normal operation to calculate monthly
emissions to demonstrate compliance with the facility-wide emission
limit. These emissions will be reported to MDE-ARMA on a quarterly
basis.
4.5.1.1.2
Auxiliary Boiler
Mattawoman proposes the use of good combustion practices, low NOx
burners (LNB), and flue gas recirculation (FGR) as LAER for controlling
NOx emissions from the auxiliary boiler. Mattawoman proposed a NOx
LAER emission rate for the auxiliary boiler of 0.01 lb/MMBtu.
PPRP’s evaluation of the NOx limit proposed by Mattawoman was based
on comparison with similar-sized boilers (10-100 MMBtu/hr). Review of
the RBLC and recently permitted boilers identified small boilers burning
exclusively pipeline quality natural gas with LNBs with NOx LAER
permitted emission rates as low as 0.01 lb/MMBtu on a 3-hour block
average basis. One permit was identified with a limit of 0.0035 lb/MMBtu
(Minnesota Steel); however, the emission limit for the boiler has not yet
been demonstrated in practice, as this unit is not yet operational.
PPRP and MDE-ARMA agree with the proposed NOx LAER emissions
limit of 0.01 lb/MMBtu to be achieved through the use of low-NOx
burners and FGR. The boiler will fire exclusively pipeline quality natural
gas and employ good combustion practices. Mattawoman must obtain
vendor guarantees to demonstrate compliance with the NOx LAER limit
and emissions will be calculated based on fuel measurements.
Mattawoman will also be required to conduct annual combustion analyses
and tune-ups to ensure good combustion practices are maintained.
MD PPRP
4-94
4.5.1.1.3
Fuel Gas Heater
Mattawoman proposes the use of good combustion practices and LNB for
controlling NOx emissions from the fuel gas heater. The proposed NOx
LAER emissions limit is 0.035 lb/MMBtu. Mattawoman proposes to be
operate the unit for 8,760 hours per year.
PPRP’s evaluation of the NOx LAER and emission limit proposed by
Mattawoman was based on comparison with similar-sized fuel gas
heaters. For the purposes of this analysis, heaters less than 100
MMBtu/hr were considered comparable to the fuel gas heater at the
proposed facility. As indicated in the RBLC and recent permit review
provided in Appendix B, fuel gas heaters burning exclusively pipeline
quality natural gas and LNBs are permitted with NOx emission rates as
low as 0.035 lb/MMBtu. Two facilities, the White Pigeon compressor
plant and Warren County, are permitted with lower emission limits for
NOx; however, the White Pigeon unit is a 3.0 MMBtu/hr heater, and the
Warren County unit has not been demonstrated in practice; therefore,
these units are not considered comparable for this LAER analysis.
PPRP and MDE-ARMA recommend a NOx LAER emission limit of 0.035
lb/MMBtu on a 3-hour block average basis. Mattawoman must obtain
vendor guarantees to demonstrate compliance with the NOx LAER limit
and emissions will be calculated based on fuel measurements.
4.5.1.1.4
Emergency Engines
The project includes the operation of two emergency diesel engines,
including one emergency generator and one fire water pump engine.
Operation of the engines will be for emergency purposes only, and no
more than 100 hours per year for maintenance and readiness testing.
Mattawoman proposes a NOx emissions limit of 4.8 g/bhp-hr for the
emergency generator, which is consistent with the NSPS Subpart IIII
limits. Mattawoman proposes a NOx limit for the fire water pump engine
of 3.0 g/bhp-hr. Note that in NSPS Subpart IIII the emission limits listed
are for combined NOx plus non-methane hydrocarbons (NOx+NMHC).
For the purposes of this Project, NMHC is equivalent to VOC emissions
and accounts for 30% of the NOx and NMHC total. Mattawoman
proposes LAER as the use of ultra-low sulfur fuel and good combustion
practices to achieve the Subpart IIII emission limits.
MD PPRP
4-95
PPRP’s review of the RBLC and other recent permits identified emergency
generators with limits lower than the proposed NOx emission rate for the
Project, with the lowest being 0.21 g/bhp-hr from the Avenal Energy
Project. However, this unit has yet to be built so the emission limit has not
yet been demonstrated in practice. The next lowest identified emission
rate is 2.6 g/bhp-hr for the Kalama Energy Center emergency generator
achieved using good combustion practices.
If emissions from the emergency generator were limited to this lower
limit, it would result in an emissions decrease of 0.7 tpy for NOx based on
500 hours per year of operation for emergency purposes, maintenance,
and readiness testing. PPRP and MDE-ARMA agree that an emission
limit of 4.8 g/bhp-hr based on a combination of NOx and NMHC
emissions to be achieved through the use of good combustion practices for
the 1490-hp emergency generator is LAER for NOx.
Review of the RBLC and other permits displayed NOx emission limits
equivalent to the 2.1 g/bhp-hr (70% of NOx+NMHC total of 3.0 g/bhp-hr)
LAER limits proposed by Mattawoman and therefore is determined to be
LAER for the emergency fire water pump.
PPRP and MDE-ARMA agree that an emission limit of 3.0 g/bhp-hr based
on a combination of NOx and NMHC emissions to be achieved through
the use of good combustion practices for the 305 hp fire water pump
engine is LAER for NOx.
Mattawoman will demonstrate compliance through the implementation of
the requirements listed under 40 CFR 60, Subpart IIII for the emergency
engines. The emergency engines will be designed to meet these emission
limits. To monitor hours of operation, Mattawoman will be required to
install a non-resettable operating hour meter (or equivalent software) on
each emergency engine.
Table 4-42 provides a summary of the NOx LAER determinations for the
Mattawoman Project.
MD PPRP
4-96
Table 4-42
Proposed NOX LAER Limitations
Emission
Source
Control Technology
Proposed LAER for NOX
Use of dry low-NOX combustor turbine
design, use of pipeline natural gas and
SCR system
CTs/HRSGs
Emissions during startup and shutdown
events shall be measured using a certified
NOX CEMS.
2.0 ppmvd @15% O2 on 3-hour block average
basis, except startup and shutdown periods;
Compliance demonstration via NOx CEMS
Startup and shutdown emissions limited to:
153 lb/event (cold startup), 132 lb/event
(warm startup), 105 lb/event (hot startup,
and 23 lb/event (shutdown).
Auxiliary Boiler
Exclusive use of pipeline quality natural
gas, LNB, FGR and good combustion
practices
0.01 lb/MMBtu, 3-hour block avg, vendor
provided guarantees
Fuel Gas Heater
Exclusive use of pipeline quality natural
gas, and good combustion practices
0.035 lb/MMBtu, 3-hour block avg, vendor
provided guarantees
Emergency
Generator
Good combustion practices and designed
to achieve emission limit
Fire Water Pump
Engine
Good combustion practices and designed
to achieve emission limit
4.5.1.2
VOC LAER
4.5.1.2.1
Combustion Turbines/HRSGs
4.8 g/bhp-hr (6.40 g/kW-hr) combined NOX
and NMHC design specification and
VOC emissions from combustion turbines are primarily the result of the
incomplete combustion of fuel. For the VOC LAER analysis conducted by
PPRP, the following control technologies were assessed.
•
Oxidation Catalyst;
•
Thermal Oxidation; and
•
Good Combustion Practices.
Thermal oxidation is technically infeasible given that the level of VOCs for
an already efficient combustion device firing gas, such as the Siemens CT
proposed by Mattawoman, would already be minimized as much as
possible via combustion. The addition of a thermal oxidizer would only
result in additional emissions from the burning of fuel, with no discernible
reduction in VOC emissions. Of the remaining control technologies that
were technically feasible, a combination of oxidation catalyst and good
combustion practices represent the most effective VOC control.
MD PPRP
4-97
Mattawoman proposes the use of oxidation catalyst along with good
combustion practices to reduce VOC emissions from the combustion
turbines. The use of an oxidation catalyst is considered the most stringent
emissions control and therefore no additional control technologies were
evaluated by Mattawoman.
Mattawoman proposes a VOC emission limit of 1.0 ppmvd @ 15% O2
without duct firing and 1.9 ppmvd @ 15% O2 with duct firing based on a
3-hour average as LAER.
Upon conducting a review of available permits and determinations for
CTs, PPRP identified recent permits with VOC limits lower than those
proposed by Mattawoman. Certain permits identified are for CTs of a
different manufacturer, CT type, model, or capacity (Brunswick,
Chouteau, Catoctin, Kalama), or are for units that have not been built or
demonstrated in practice (CPV Wawayanda, ODEC Wildcat Point, Green
Energy, Hickory Run, Huntington Beach, Marshalton, Moxie Patriot, St
Joseph).
A series of discussions and correspondence transpired with Mattawoman
with respect to the proposed VOC LAER limit. In response to PPRP Data
Request No. 3-5, Mattawoman noted that the projects identified by PPRP
and MDE-ARMA are either different vendor CTs, or CTs which utilize
Siemens SGT6-5000F series units. Mattawoman is proposing a SGT68000H series unit and the proposed units are significantly larger than the
SGT6-5000F units and have different combustion and emission
characteristics. In addition, Mattawoman introduced in response to PPRP
Data Request No. 15-4, that the proposed units will employ larger duct
burner capacity (687.3 MMBtu/hr) than other projects identified. The
larger heat input rate of the duct burner introduces a higher rate of natural
gas for combustion resulting in increased VOC emissions. However,
although the duct burner heat input is higher than other CT projects, there
is only a marginal increase in volumetric flow rate associated with the
increased duct burner capacity. As a result, the VOC concentration
increases due to the higher heat input rate of the duct burner with only a
marginal increase in exhaust flow rate for the CTs.
The Mattawoman CTs will employ state of the art oxidation catalyst
control technology to reduce VOC emissions, which provides the
maximum level of control currently available for this application.
Mattawoman further emphasized that the proposed VOC LAER limits of
1.0 ppmvd @ 15% O2 without duct firing and 1.9 ppmvd @ 15% O2 with
duct firing (based on a 3-hour block average) are consistent with other
LAER determinations given the duct burner capacity. These VOC levels
MD PPRP
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are the lowest emission rates included in the Siemens specification sheets
for the SGT6-8000H CTs.
PPRP and MDE-ARMA concur that VOC LAER is an emissions limit not
to exceed 1.0 ppmvd @ 15% O2 without duct burning, and 1.9 ppmvd @
15% O2 with duct burning on a 3-hour block average basis. Mattawoman
shall achieve compliance with the VOC LAER limits through the use of
good combustion practice, the use of pipeline natural gas, and operation
of an oxidation catalyst at all times when the CTs/HRSGs are operating,
except during startup and shutdown events. Compliance will be
demonstrated based on three 1-hour stack tests (3-hour block average)
through the use of Method 18, 25A, or other test method requiring MDE
approval.
To ensure continuous compliance with VOC LAER, except during periods
of startup and shutdown, Mattawoman will utilize CO CEMS data as a
surrogate for VOC emissions. Mattawoman will develop a correlation
between CO and VOC emissions during an initial stack test following EPA
Reference Method 18, 25A or equivalent and with use of the CO CEMS,
and then will operate the CO CEMS to demonstrate compliance with the
VOC limits. Stack testing of the CT/HRSG will be conducted annually
after the initial test to verify the CO and VOC emission correlation or to
establish a new correlation should conditions have changed.
PPRP and MDE-ARMA determined based on a review of other permits
and the RBLC database, that post-combustion controls are not considered
technically feasible during startup and shutdown conditions. Therefore,
LAER for natural-gas fired CTs for startup and shutdown emissions is to
ensure that correct procedures are followed to allow for optimal
performance during normal operations, and that emissions during each
startup and shutdown event will be minimized.
PPRP and MDE-ARMA have determined that the CTs will be subject to
the following limits during startup and shutdown, as provided to
Mattawoman by the manufacturer, Siemens:
•
•
•
MD PPRP
VOC emissions will be limited to 301 pounds per event for each
cold startup, 258 pounds per event for each warm startup, and 207
pounds per event for each hot startup, as determined by CEMS.
VOC emissions will be limited to 63 pounds per shutdown event,
as determined by CEMS.
The startup and shutdown emissions must also be included in the
facility-wide annual emission limits.
4-99
During periods of startup and shutdown, Mattawoman will be required to
take all reasonable efforts to minimize emissions. Mattawoman will be
required to design the CTs to meet the startup and shutdown emission
limits. Mattawoman will be required to calculate startup and shutdown
emissions based on the number of these events and the projected emission
factor. Mattawoman will be required to include these emissions in the
facility-wide cap to minimize emissions during those times.
4.5.1.2.2
Auxiliary Boiler
Similar to the CTs, VOC emissions from auxiliary boilers are primarily the
result of the incomplete combustion of fuel. The auxiliary boilers are
expected to provide efficient combustion of natural gas. Mattawoman
proposes the exclusive use of pipeline-quality natural gas and good
combustion practices to achieve a VOC LAER emissions limit of 0.003
lb/MMBtu for the auxiliary boiler.
PPRP reviewed the RBLC database and other recent permits issued for
small-sized natural gas-fired boilers (10-100 MMBtu/hr) to identify VOC
emission limits permitted at other facilities. Several small boilers with
lower emission limits than the 0.003 lb/MMBtu proposed by Mattawoman
were identified. These facilities include Harrah’s Operating Company
and MGM Mirage. MGM Mirage and Harrah’s had reduced emission
rates based on their Las Vegas location in a CO nonattainment area. The
co-benefit of more stringent CO control was reduced VOC emissions
limits. There are no other facilities that have a VOC LAER emissions limit
for an auxiliary boiler in this size range below 0.003 lb/MMBtu which has
been demonstrated in practice. Therefore, PPRP and MDE-ARMA concur
with the proposed VOC LAER limit of 0.003 lb/MMBtu for the auxiliary
boiler.
Mattawoman will be required to meet the VOC emissions limit of 0.003
lb/MMBtu on a 3-hour block average. Mattawoman will be required to
obtain vendor guarantees to demonstrate compliance with the VOC LAER
limit and emissions will be calculated using fuel measurements.
4.5.1.2.3
Fuel Gas Heater
Similar to the CTs and auxiliary boiler, VOC emissions from the fuel gas
heater are primarily the result of the incomplete combustion of fuel.
Mattawoman proposes the use of good combustion practices and
exclusive use of natural gas as fuel to result in a VOC LAER emission rate
MD PPRP
4-100
of 0.0054 lb/MMBtu. PPRP independently reviewed the RBLC database
and other permits issued for fuel gas heaters of similar size. Based on this
review, PPRP and MDE-ARMA concur with the VOC LAER emission
limit of 0.0054 lb/MMBtu for the fuel gas heater.
Mattawoman will be required to meet the VOC emissions limit of 0.0054
lb/MMBtu on a 3-hour block average. Mattawoman will be required to
obtain vendor guarantees to demonstrate compliance with the VOC LAER
limit and emissions will be calculated using fuel measurements.
4.5.1.2.4
Emergency Engines
The Project includes the operation of two emergency diesel engines,
including one emergency generator and one fire water pump engine.
Operation of the engines will be for emergency purposes only, and no
more than 100 hours per year for maintenance and readiness testing.
Mattawoman proposes a VOC limit for the emergency generator based on
the emission rates specified in EPA’s NSPS Subpart IIII regulation. The
proposed NOx + NMHC LAER limit for the emergency generator is 4.8
g/bhp-hr. Mattawoman estimated that VOC emissions account for 30% of
this combined total, the VOC emission rate proposed as LAER is equal to
1.4 g/bhp-hr. A review of the RBLC and recent permits identified
emergency engines with VOC limits below the NSPS-based NOx and VOC
emission limit proposed for the project, with the lowest being 0.01
g/bhp-hr for the Moxie Liberty LLC and Moxie Energy LLC facilities.
Based on a more detailed review of these permits, the combined NOx and
VOC limit was 4.94 g/bhp-hr which is higher than the limit of 4.8 g/bhphr proposed for the proposed Project. Similarly, for the next lowest limit
identified (Sabine Pass), the combined NOx and VOC emission limit is
12.27 lb/hr or 8.4 g/hp-hr. This is also higher than the 4.8 g/hp-hr limit
for the proposed Project. GP Allendale is the only other facility that
appears to have a lower emission limit. GP Allendale has a combined
NOx and VOC emission limit of 11.72 lb/hr or 3.8 g/hp-hr. Should
Mattawoman be required to comply with a limit as low as 3.8 g/hp-hr, the
net potential decrease in VOC emissions would be 0.82 tpy. Given the
degree of emission reduction associated with achieving lower VOC limits,
PPRP and MDE-ARMA believe that there is no environmental benefit in
establishing emission limits for the emergency generator below the NSPS
limit.
MD PPRP
4-101
Mattawoman proposes a VOC limit for the fire water pump engine based
on the emission rates specified in EPA’s NSPS Subpart IIII regulation. The
proposed VOC LAER limit for the firewater pump is 0.90 g/bhp-hr based
on the VOC emission estimate accounting for 30% of the NOx + NMHC
total of 3.0 g/bhp-hr. A review of the RBLC and recent permits identified
emergency engines with VOC limits below the NSPS-based NOx and VOC
emission limit proposed for the Project, with the lowest being 0.05
g/bhp-hr at the Crescent City facility in Louisiana. However, the Crescent
City facility has a combined NOx and VOC limit of 9.5 g/bhp-hr which is
much greater than that proposed for this Project. The Moxie Liberty and
Freedom facilities in Pennsylvania have a lower VOC limit permitted for
the fire water pump as well, but the combined NOx and VOC emissions
are 3.6 g/bhp-hr, which is above that proposed by Mattawoman.
PPRP and MDE-ARMA concur that LAER for the emergency generator is
a limit of 4.8 g/hp-hr (6.4 g/kW-hr) based on a combination of NOx and
NMHC emissions that will be achieved through the use of good
combustion practices. PPRP and MDE-ARMA also concur that LAER for
the fire water pump engine will be the limit of 3.0 g/hp-hr (4.0 g/kW-hr)
based on a combination of NOx and NMHC emissions that will be
achieved through the use of good combustion practices.
Mattawoman will be required to design the emergency engines to meet
these emission limits. To monitor hours of operation, Mattawoman will
install a non-resettable operating hour meter (or equivalent software) on
each emergency engine.
4.5.1.2.5
Equipment Leaks
The proposed Project will result in fugitive VOC emissions from potential
leaks in the natural gas piping equipment components. These
components include pumps, flanges, connectors, pump seals, and
pressure relief valves. A review of recent permits and the RBLC by PPRP
determined that VOC LAER is to implement an LDAR program. To meet
VOC LAER, PPRP and MDE-ARMA require that Mattawoman will
implement an LDAR Audio, Visual, Olfactory (AVO) program to detect
the presence of fugitive leaks and to mitigate fugitive emissions from
components.
PPRP and MDE-ARMA recommend a condition that requires the AVO
program to be developed, conducted, and documented on a weekly basis.
Leaks identified from the AVO inspections must be repaired within five
days of discovery, and the repairs documented and records maintained.
MD PPRP
4-102
Table 4-43 provides a summary of the VOC LAER determinations for the
Mattawoman Project.
Table 4-43
Proposed VOC LAER Determinations
Emission
Source
Control Technology
Proposed LAER for VOC
The use of pipeline natural gas, good
combustion practices, and use of an oxidation
catalyst
CTs/HRSGs
Startup and shutdown emissions limited to:
301 lb/event (cold startup), 258 lb/event
(warm startup), 207 lb/event (hot startup,
and 63 lb/event (shutdown).
Auxiliary
Boiler
The exclusive use of pipeline quality natural
gas and good combustion practices
0.003 lb/MMBtu, 3-hour block avg., vendor
provided guarantee
Fuel Gas
Heater
The exclusive use of pipeline quality natural
gas and good combustion practices
0.005 lb/MMBtu, vendor provided guarantee
Emergency
Generator
Firewater
Pump
Equipment
Leaks
4.5.2
Take reasonable efforts to minimize
emissions during startup and shutdown
periods. Include emissions during startup
and shutdown events in the facility-wide
emissions cap.
1.0 ppmvd at 15% O2 (without duct firing)
1.9 ppmvd at 15% O2 (with duct firing)
3-hour block avg., Method 18, 25A stack test
or equivalent method approved by
MDE-ARMA
Use only ULSD, good combustion practices,
designed to achieve emission limit, and
limited hours of operation
Use only ULSD, good combustion practices,
designed to achieve emission limit, and
limited hours of operation
Implement LDAR Program
Facility-Wide VOC Emissions Cap of 144.1
tons per 12-month rolling period
Offsets
In addition to achieving NOx and VOC LAER requirements, triggering
NA-NSR requires Mattawoman to obtain NOX and VOC emission offsets
for the Project. In accordance with COMAR 26.11.17, Mattawoman must
meet the “reasonable further progress requirements” of the CAA by
attaining NOx and VOC creditable emission offsets at a ratio of 1.3 to 1.0.
The NOx and VOC offsets may be from sources within the ozone
nonattainment area in which the proposed facility will be located.
Specifically, under COMAR 26.11.17.04D:
(1) Generally, ERCs are acceptable if obtained from within the same
area as the new or modified emissions unit. The [MDE-ARMA]
Department may allow the owner or operator to obtain VOC or
NOx emission reductions from other areas if:
MD PPRP
4-103
(a) The other area has an equal or higher nonattainment
classification than the area in which the emissions unit is
located; and
(b) Emissions of the particular pollutant from the other area
have been demonstrated to contribute to a violation of the
National Ambient Air Quality Standard in the area in which the
new emissions unit is located.
(2) The Department shall give preference to ERCs from emissions
units located as close to the proposed emissions unit site as
possible.
Projected NOx emissions from the Project are 220.7 tpy, which will require
287 tpy of offsets, and projected VOC emissions are 144.1 tpy, which will
require 187 tpy of offsets. Mattawoman will need to provide
documentation to MDE-ARMA and ensure that the necessary offsets are
identified and obtained as required prior to commencement of
construction.
4.5.3
Additional NA-NSR Requirements
NA-NSR requires Mattawoman to certify that all existing sources owned
or operated in the same state as the proposed source are in compliance
with all emission limitations and standards under the CAA. Mattawoman
provided certification in response to a data request that all existing
sources owned or operated in the State of Maryland are in compliance
with all emission limitations and standards under the CAA.
Mattawoman conducted an alternative analysis in their July 2013 CPCN
application in which they evaluated alternate sites and alternative
technology for the CTs/HRSGs to meet the purpose of the Project,
meeting the purpose of the Project though conservation of other energy
sources, and/or changing the location of the Project. PPRP and
MDE-ARMA reviewed this analysis and consider it to be adequate.
The applicant is also required to demonstrate that the benefits of the
proposed source outweigh the environmental and social costs imposed by
the construction of the source. Neither potential air emissions from the
operation of the Project, nor from the temporary construction activities
that will take place during installation of the Project are expected to result
in significant, adverse local or regional impacts to air quality, or to local
vegetation (see Section 4.4.3). Socioeconomic impacts associated with the
MD PPRP
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Project are described in Section 5.3 of this Environmental Review
Document.
4.6
REGULATORY APPLICABILITY ANALYSIS
As a part of its review of the CPCN application, PPRP and MDE-ARMA
determined the applicable air regulatory requirements for all air emission
sources proposed to be installed as a part of this Project. The applicable
regulatory requirements and the associated compliance demonstration
approaches are discussed in this section of the document.
4.6.1
Federal Regulatory Requirements
4.6.1.1
New Source Performance Standards (NSPS)
4.6.1.1.1
Standards for Stationary Combustion Turbines (40 CFR Part 60 Subpart
KKKK)
The CTs, HRSG, and duct burners are subject to 40 CFR §60 Subpart
KKKK, “Standards of Performance for Stationary Combustion Turbines.”
All stationary gas turbines with a heat input at a peak load equal to or
greater than 10.7 gigajoules per hour (10 MMBTU/hr), based on the
higher heating value of the fuel, which commenced construction,
modification, or reconstruction after 18 February 2005 are subject to this
Subpart. As per §60.4305(b), stationary CTs regulated under Subpart
KKKK are exempt from the requirements of Subpart GG, and HRSGs and
duct burners regulated under Subpart KKKK are exempt from the
requirements of NSPS Subparts Da, Db, and Dc.
Applicable Requirements
The NSPS includes the following requirements: general compliance
requirements (§60.4333), monitoring requirements (§60.4335-§60.4370),
reporting requirements (§60.4375-§60.4395), and performance testing
(§60.4400-§60.4415). Mattawoman will also be subject to applicable
notification, monitoring and reporting and related applicable provisions
of 40 CFR §60.7 and §60.8.
The CTs are subject to a NOx limit of 15 ppmvd at 15% oxygen or 0.43
lb/MWh gross energy output and SO2 emissions limit of 0.90 lb/MWh
gross energy output or 0.060 lb/MMBTU.
MD PPRP
4-105
Recommended Compliance Demonstration Approach
a.
Monitoring –
Mattawoman will install and operate a continuous emission
monitoring system (CEMS) at the outlet of the CT/HRSG stacks.
The system should continuously analyze, monitor, and record the
concentrations of NOX.
Compliance with the SO2 emission standard shall be demonstrated
by either of the following:
i.
The fuel quality characteristics in a current, valid purchase
contract, tariff sheet or transportation contract for the fuel,
specifying that the maximum total sulfur content for natural gas
is 20 grains of sulfur or less per 100 standard cubic feet, has
potential sulfur emissions of less than 26 ng SO2/J (0.060 lb
SO2/MMBTU) heat input.
ii.
Representative fuel sampling data which show that the sulfur
content of the fuel does not exceed 26 ng SO2/J (0.060 lb
SO2/MMBTU) heat input. At a minimum, the amount of fuel
sampling data specified in Section 2.3.1.4 or 2.3.2.4 of Appendix
D to 40 CFR §75 is required.
If Mattawoman elects to comply with the minimum fuel sulfur
content limit under 40 CFR§ 60.4330, Mattawoman must monitor the
total sulfur content of the CT’s fuel using the methods described in
40 CFR §60.4415 at a frequency described in 40 CFR §60.4370.
Alternatively, if the total sulfur content of the gaseous fuel during the
most recent performance test was less than half the applicable limit,
ASTM D4084-82, 94, 05, D4810-88 (1999), D5504-01, or D6228-98
(2003), or Gas Processors Association Standard 2377-86, may be used
to assess compliance with the applicable fuel sulfur limit [40 CFR
§60.4360].
b.
MD PPRP
Reporting – Mattawoman must submit reports of excess emissions
and monitor downtime, in accordance with §60.7(c). Excess
emissions must be reported for all periods of unit operation,
including start-up, shutdown, and malfunction. Units that perform
an annual performance test must submit these reports within 60 days
of testing.
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c.
4.6.1.1.2
Performance Testing – As per §60.8, Mattawoman is required to
conduct an initial performance test. Subsequent NOx performance
tests shall be conducted on an annual basis (no more than 14
calendar months following the previous performance test. EPA
Method 7 or 7E will be used for performance testing.
NSPS for Small Industrial-Commercial-Institutional Steam Generating
Units (40 CFR Part 60 Subpart Dc)
NSPS Subpart Dc is applicable to all steam generating units greater than
10 MMBtu/hr and less than 100 MMBtu/hr. The auxiliary boiler will be
subject to these requirements. Mattawoman must address the reporting as
indicated by 40 CFR §60.48c(a). The auxiliary boiler is not subject to the
SO2 emission limits or particulate emission limits as it does not combust
coal or oil.
As mentioned earlier, the duct burners are exempt from the requirements
of this NSPS as they are covered by NSPS Subpart KKKK. The fuel gas
heater is also exempt from this requirement according to the 40 CFR
§60.41c definition of steam generating units.
Notification: Mattawoman is required to notify EPA and MDE-ARMA of
the date of completion of construction and actual startup (§60.48c(a)).
Compliance Demonstration
Recordkeeping: Mattawoman is required to maintain records of natural gas
fuel use (§60.48c(g)(1) – (3)).
Work Practice Standards: Mattawoman is required to maintain records of
any maintenance performed on the boiler for two years from the date of
the record (§60.48c(i)).
4.6.1.1.3
NSPS for Stationary Compression Ignition Internal Combustion Engines
(40 CFR Part 60 Subpart IIII)
The emergency generator (1,490 hp) and the firewater pump (305 hp)
engines are subject to the requirements of this regulation as they are
considered compression ignition (CI) reciprocating internal combustion
engines (RICE) installed after July 2005. These engines are subject to the
application monitoring, compliance, testing, notification, reporting, and
recordkeeping requirements (40 CFR §60.4200 et seq.) and related
applicable provisions of 40 CFR §60.7 and §60.8. Emission limits for these
engines are noted in Table 4-44. Note that the engines are not subject to
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the Tier 4 requirements under Subpart IIII given the engines have cylinder
displacement less than 10 liters per cylinder.
Table 4-44
Emission Standards for the Emergency Engines (g/bhp-hr)
Emergency Engine
Model Year
NMHC+NOX
CO
PM
305 hp Fire Water Pump
225<kW<450 (300<hp<600)
2009+
3
2.6
0.15
1,490 hp Emergency Generator
Displacement <10 and <2,237kW
(3,000hp)
2007+
4.8
2.6
0.15
Notifications
As the emergency generator and firewater pump engines are used only for
emergency purposes, they are not subject to the initial notification
requirements of the rule.
a.
Fuel: The sulfur content in the distillate fuel oil is limited to 15 ppm
(0.0015%).
b.
Compliance: Mattawoman is required to install a non-resettable
hour meter prior to the startup of each engine as per 40 CFR
§60.4209(a).
c.
Recordkeeping: Mattawoman is required to maintain the following
records:
i.
A copy of each notification submitted to comply with this
subpart.
ii.
Records of the occurrence and duration of each malfunction of
operation or the air pollution control and monitoring equipment.
iii.
Records of all required maintenance on the air pollution control
and monitoring equipment.
iv.
Records of hours of operation and the reasons for operating the
engines (maintenance, readiness, or emergency).
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v.
4.6.1.1.4
Records of actions taken during periods of malfunction to
minimize emissions in accordance with 63.6605(b), including
malfunctioning process and air pollution control and monitoring
equipment to its normal or usual manner of operation.
NSPS for Steam Generating Units for Greenhouse Gases (40 CFR Part 60
Subpart TTTT)
On April 13, 2012, EPA proposed NSPS for greenhouse gases (GHGs)
from fossil fuel-fired electrical utilities. The proposed rule limits GHG
emissions from new electrical utility units to 1,000 lb/MWh. A revised
version of the regulation was proposed on September 20, 2013.
At this time, there are no applicable requirements associated with this
regulation for the proposed sources at the facility. However, upon
promulgation, the proposed NSPS limit will become the “BACT floor” for
GHG emissions; i.e., the GHG BACT limit will be required to be at least as
stringent as the NSPS limit. Compliance with the NSPS limit will be
demonstrated using a certified continuous emissions monitoring system
(CEMS). The proposed BACT limit of 865 lb/MWh would comply with
the NSPS emission limit of 1,000 lb/MWh, as identified in the proposed
rule.
4.6.1.2
National Emission Standards for Hazardous Air Pollutants (NESHAPs)
NESHAPs are federal HAP requirements in 40 CFR §63 that apply
generally to "major" sources of HAPs, defined as facilities with the
potential to emit 10 tpy or more of any single HAP, or 25 tpy or more of
two or more HAPs. HAP standards, known as Maximum Achievable
Control Technology (MACT) standards, for major HAP sources are
established for classes or categories of sources. There are, at present, no
source category MACT standards for CTs such as those proposed by
Mattawoman. Some MACT standards, known as “area source MACT”
standards, apply to minor source HAP facilities.
The total potential HAP emissions for the facility are projected to be less
than 25 tpy for all HAPs combined; therefore, the proposed Project is not
considered a major HAP source and so no source-specific MACT
standards apply.
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4.6.1.2.1
NESHAP for Combustion Turbines (40 CFR Part 63 Subpart YYYY)
NESHAP Subpart YYYY applies to stationary CTs located at a major
source of HAP emissions. As an area source of HAPs, the requirements of
this subpart do not apply to the proposed Project.
4.6.1.2.2
NESHAP for RICE (40 CFR Part 63 Subpart ZZZZ)
The emergency generator and firewater pump engine are subject to the
requirements of NESHAP Subpart ZZZZ for reciprocating internal
combustion engines (RICE). Pursuant to 40 CFR §63.6590(c)(1), a new
stationary RICE located at an area source is required to meet the
applicable requirements under 40 CFR Part 60 Subpart IIII.
Mattawoman is required to use diesel fuel that meets the requirements in
40 CFR 80.510(b) for non-road diesel fuel, except that any existing diesel
fuel purchased (or otherwise obtained) prior to January 1, 2015, may be
used until depleted (63.6604(b)). As per §80.510(b), the sulfur content of
the diesel fuel is limited to 15 ppm.
The generator is required to be operated to minimize emissions at all
times in a manner consistent with safety and good air pollution practices.
Notifications
No additional notification is required for emergency units.
4.6.1.2.3
NESHAP for Industrial, Commercial, Institutional Boilers and Process
Heaters (40 CFR Part 63 Subpart DDDDD)
The rule is applicable to all boilers and process heaters located at a major
source of HAP emissions. The proposed auxiliary boiler and fuel gas
heater are therefore not subject to this rule. This rule is commonly
referred to as the Major Source Boiler MACT rule.
4.6.1.2.4
NESHAP for Industrial, Commercial, Institutional Boilers and Process
Heaters (40 CFR Part 63 Subpart JJJJJJ)
There is an area source MACT for industrial, commercial and institutional
boilers and process heaters (40 CFR §63, Subpart JJJJJJ), known as the
“Boiler GACT”. The Boiler GACT does not apply to any of the proposed
combustion sources because the only source considered an “affected
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source” under Subpart JJJJJJ is the auxiliary boiler and according to 40
CFR §63.11195, a gas fired boiler is not subject to any requirements in this
subpart.
4.6.1.2.5
NESHAP for Coal- and Oil-fired Electrical Utilities (40 CFR Part 63
Subpart UUUUU)
The rule is applicable only to coal-and oil-fired electrical utility systems.
Since the CTs and duct burners will be fired on exclusively natural gas,
they are exempt from applicability to this rule.
4.6.1.3
Acid Rain Program (40 CFR Parts 72 through 76)
The proposed CTs meet the definition of an “affected unit” as defined in
40 CFR §72.6, and are therefore subject to the requirements of the Acid
Rain program, including emissions standards (40 CFR §72.9) and
monitoring requirements (40 Part 75), among other requirements. In
addition, Mattawoman is required to apply for, and obtain, an Acid Rain
permit (under 40 CFR 72.30); terms of the Acid Rain permit will be
incorporated into the facility’s Title V operating permit by MDE-ARMA.
Mattawoman is required to submit a complete Acid Rain permit
application at least 24 months prior to start of operation of the
CTs/HSRGs.
Mattawoman is required to install CEMs for NOx and SO2 to meet the
monitoring requirements of 40 Part 75. As a surrogate to installing SO2
CEMS, Mattawoman can opt to monitor the sulfur content of the fuel.
Mattawoman will be required to maintain documentation of the sulfur
content through fuel receipt records.
4.6.1.4
Clean Air Interstate Rule (CAIR)/Cross-State Air Pollution Rule (CSAPR)
The Clean Air Interstate Rule (CAIR) was a federal rule promulgated in
March 2005 that implements a cap and trade program on power plant
NOX and SO2 emissions in the eastern half of the United States. This rule
was promulgated for implementation under 40 CFR §97. Maryland has
promulgated implementing regulations under COMAR 26.11.28.
According to 40 CFR §97.4, CAIR applied to any emission unit that, at any
time after January 1, 1995, has a nameplate generating capacity of greater
than 25 MW and sells any amount of electricity or has a maximum design
heat input of greater than 250 MMBtu/hr.
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On July 6, 2011, the U.S. EPA finalized the Cross-State Air Pollution Rule
(CSAPR), which replaces CAIR. The first phase of compliance was
scheduled to begin January 1, 2012 for annual SO2 and annual NOX
emissions and May 1, 2012 for ozone season NOX emissions. In August
2012, CSAPR was vacated pending appeal. On April 29, 2014, the
Supreme Court reversed the lower court’s decision and reinstated the
CSAPR.
Compliance with CSAPR Phase 1 emission budget program is required in
2015 and 2016, while the program’s Phase 2 emission budgets and
assurance provisions are effective in 2017 and beyond.
4.6.1.5
Compliance Assurance Monitoring (CAM) Plan
Compliance Assurance Monitoring (CAM) applies to emissions units at
“major” sources that are required to obtain a Title V operating permit, and
that meet all three of the following criteria (40 CFR §64.2a):
“(1) The unit is subject to an emission limitation or standard
for the applicable regulated air pollutant (or a surrogate
thereof), other than an emission limitation or standard that is
exempt under paragraph (b)(1) of this section;
(2) The unit uses a control device to achieve compliance with
any such emission limitation or standard; and
(3) The unit has potential pre-control device emissions of the
applicable regulated air pollutant that are equal to or greater
than 100 percent of the amount, in tons per year, required for
a source to be classified as a major source.”
The only air emission source at the proposed Mattawoman facility
which meets all three criteria described above is the CTs/duct
burners. However, since the CTs/duct burners are subject to NSPS
and MACT standards, no additional CAM requirements are
applicable to these units (§64.2(b)(1)(i)).
4.6.1.6
Risk Management Planning
This regulation covers the requirements for owners or operators of
stationary sources concerning the prevention of accidental releases, and
the State accidental release prevention programs approved under section
112(r) and codified as 40 CFR 68. This regulation applies to owners and
operators of facilities, which store regulated substances in a process
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greater than certain threshold quantities. Under Subpart G of the
regulation, a facility is required to develop a Risk Management Plan
(RMP) if the quantity of regulated substances exceeds the threshold
quantities. Ammonia is one of the regulated substances covered by the
regulation and is proposed to be used in the SCR system associated with
the CTs. However, under 40 CFR §68.130, only ammonia stored in
concentration greater than 20% is covered by the regulation. Mattawoman
is proposing to use ammonia at concentrations of less than twenty percent
(20%) and therefore, the requirements of this regulation do not apply to
the facility.
4.6.2
State Regulatory Requirements
In addition to the federal regulatory requirements, the proposed Project
will be subject to several State of Maryland air regulations which are
codified at Code of Maryland Air Regulations (COMAR) 26.11. The
requirements are listed below for the entire facility and for specific pieces
of equipment, as applicable.
a) COMAR 26.11.01.03 - Delineation of Areas
The proposed Project is located in Area IV of the State, which means
the Washington metropolitan area of the State comprising the counties
of Montgomery and Prince George's.
b) COMAR 26.11.01.04A-Requirements for Testing:
MDE-ARMA may require Mattawoman to conduct or have conducted
testing to determine compliance with the permit. MDE-ARMA, at its
option, may witness or conduct these tests. This testing will be done at
a reasonable time, and all information gathered during a testing
operation will be provided to both parties.
c) COMAR 26.11.01.04B-Requirements for Monitoring:
MDE-ARMA or the control officer (appropriate health officer at Prince
George’s County under COMAR 26.11.01.01B.12) may require
Mattawoman to install, use, and maintain monitoring equipment or
employ other methods as specified by MDE-ARMA or the control
officer to determine the quantity or quality, or both, of emissions
discharged into the atmosphere and to maintain records and make
reports on these emissions to MDE-ARMA or the control officer in a
manner and on a schedule approved by MDE-ARMA or the control
officer.
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i. MDE-ARMA or the control officer, at reasonable times, shall have
access to and be permitted to copy any records, inspect any
monitoring equipment or methods required under this section.
ii. Except when otherwise specified by MDE-ARMA or the control
officer, records required under this regulation shall be available
for inspection by MDE-ARMA and the control officer for a period
of not less than 90 days.
iii. All records and reports submitted to MDE-ARMA or the control
officer required under this regulation shall be available for public
inspection.
d) COMAR 26.11.01.04C-Emissions Test Methods:
Compliance with the emissions standards and limitations in these
Conditions shall be determined by the test methods designated and
described in these Conditions or other test methods submitted to and
approved by MDE-ARMA.
e) COMAR 26.11.01.05-1 and COMAR 26.11.02.19C and COMAR
26.11.02.19D - Emissions Certification Report:
i. Requires Mattawoman to certify annual emissions of regulated
pollutants from the facility on a calendar year basis.
1)
The certification shall be on forms obtained from the
Department and submitted to MDE-ARMA not later than
April 1 of the year following the year for which the
certification is required;
2)
The individual making the certification shall certify that the
information is accurate to the individual’s best knowledge.
The individual shall be:
a. Familiar with each source for which the certifications
forms are submitted, and
b. Responsible for the accuracy of the emissions
information.
ii. Mattawoman is required to maintain records necessary to support
the emission certification, including the following information if
applicable:
1) The total amount of actual emissions of each regulated
pollutant and the total of all regulated pollutants;
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2) An explanation of the methods used to quantify the emissions
and the operating schedules and production data that were
used to determine emissions, including significant
assumptions made;
3) Amounts, types, and analyses of all fuels used;
4) Emission data from continuous emission monitors that are
required by COMAR 26.11 or EPA regulations, including
monitor calibration and malfunction information;
5) Identification, description, and use records of all air pollution
control equipment and compliance monitoring equipment,
including significant maintenance performed, malfunctions
and downtime, and episodes of reduced efficiency of this
equipment;
6) Limitations on source operation or any work practice
standards that significantly affect emissions;
7) Other relevant information as required by MDE-ARMA; and
8) The logs and other records of information required by
COMAR 26.11.02.19C(1) shall be retained for a period of 5
years and made available to MDE-ARMA upon request.
f) COMAR 26.11.01.07C-D-Malfunctions and Other Temporary
Increases of Emissions:
i. Requires Mattawoman, in the case of any occurrence of excess
emissions expected to last or actually lasting for 1 hour or more,
to report the onset and the termination of the occurrence to MDEARMA by telephone. Telephone reports of excess emissions shall
include the following information:
1) The identity of the installation and the person reporting;
2) The nature or characteristics of the emissions (for example,
hydrocarbons, fluorides);
3) The time of occurrence of the onset of the excess emissions
and the actual or expected duration of the occurrence; and
4) The actual or probable cause of the excess emissions.
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ii. When requested by MDE-ARMA, Mattawoman shall submit a
written report to MDE-ARMA within 10 days of receiving the
request regarding excess emissions; the report shall contain the
information required in COMAR 26.11.01.07D(2).
g) COMAR 26.11.01.08 - Determination of Ground Level
Concentrations
Mattawoman is required to demonstrate compliance with all
applicable NAAQS. As a part of compliance with the PSD
requirements, Mattawoman has performed an air quality analysis
which demonstrates compliance with the NAAQS.
h) COMAR 26.11.01.11 - Continuous Emission Monitoring
Requirements
Before installing a CEM, Mattawoman is required to submit to
MDE-ARMA a plan containing the CEM design specifications,
proposed location, and a description of a proposed alternative
measurement method. The location of the CEM, the amount and
recording of measurements, and reporting requirements are specified
by COMAR 26.11.01.11.
i) COMAR 26.11.03.01- Applicability and General Requirement:
Requires Mattawoman to apply for and obtain a Part 70 operating
permit.
j) COMAR 26.11.04.02 - Ambient Air Quality Standards, Definitions,
Reference Conditions, and Methods of Measurement
Mattawoman shall comply with applicable NAAQS using dispersion
modeling.
k) COMAR 26.11.06.01 - Definitions (General Emission Standards,
Prohibitions, and Restrictions)
B.(1) "Installation", for the purpose of COMAR 26.11.06, means an
installation as defined in COMAR 26.11.01.01 that can operate
independently and that causes VOC emissions to the atmosphere. If
equipment at premises does not operate independently but operates as
part of a process line, the process line is considered to be the
installation. All the air emission sources proposed in this Project are
considered an installation.
l) COMAR 26.11.06.02C -Visible Emissions Standards
Mattawoman is located in Area IV (Prince George’s County). In Areas
III and IV a person may not cause or permit the discharge of emissions
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from any installation or building, other than water in an uncombined
form, which is visible to human observers.
m) COMAR 26.11.06.03B(2) - Particulate Matter Emissions from
Confined Sources – The Project air emission sources including the
CTs/HRSGs, auxiliary boiler, fuel gas heater and diesel generators are
subject to this requirement. Mattawoman may not cause or permit
particulate matter to be discharged into the outdoor atmosphere from
any other installation, particulate matter in excess of 0.03 gr/SCFD
(68.7 mg/dscm).
n) COMAR 26.11.06.03C – Particulate Matter Emissions from
Unconfined Sources - Prohibits Mattawoman from causing or
permitting emissions from an unconfined source without taking
reasonable precautions to prevent particulate matter from becoming
airborne. These reasonable precautions shall include, when
appropriate as determined by MDE-ARMA, the installation and use of
hoods, fans, and dust collectors to enclose, capture, and vent
emissions. In making this determination, MDE-ARMA shall consider
technological feasibility, practicality, economic impact, and the
environmental consequences of the decision.
o) COMAR 26.11.06.03D-Particulate Matter From Materials Handling
and Construction - Prohibits Mattawoman from causing or permitting
any material to be handled, transported, or stored, or a building, its
appurtenances, or a road to be used, constructed, altered, repaired, or
demolished without taking reasonable precautions to prevent
particulate matter from becoming airborne.
p) COMAR 26.11.06.05 - Sulfur Compounds from Other than FuelBurning Equipment – Prohibits Mattawoman from causing or
permitting the discharge into the atmosphere from installations other
than fuel burning equipment of gases containing more than 500 ppm
of sulfur dioxide.
q) COMAR 26.11.06.08-Nuisance - Prohibits Mattawoman from
operating or maintaining a source in such a manner that a nuisance or
air pollution is created. This is a state-only enforceable requirement.
r) COMAR 26.11.06.09- Odors- Prohibits Mattawoman from causing or
permitting the discharge into the atmosphere of gases, vapors, or
odors beyond the property line in such a manner that a nuisance or air
pollution is created. This is a state-only enforceable requirement.
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s) COMAR 26.11.06.12-Control of NSPS Sources - Prohibits
Mattawoman from constructing, modifying, or operating, or causing to
be constructed, modified, or operated, a New Source Performance
Standard (NSPS) source as defined in COMAR 26.11.01.01B(23), which
results or will result in violation of the provisions of 40 CFR §60, as
amended;
t) COMAR 26.11.06.14-Control of PSD Sources- Prohibits Mattawoman
from constructing, modifying, or operating, or causing to be
constructed, modified, or operated, a Prevention of Significant
Deterioration (PSD) source, as defined in COMAR 26.11.01.01B(37),
which will result in violation of any provision of 40 CFR §52.21, as
published in the 2009 edition, as amended by the “Prevention of
Significant Deterioration and Title V Greenhouse Gas Tailoring Rule”
(75 FR 31514);
u) COMAR 26.11.07 – Open Fires - Prohibits Mattawoman from causing
or permitting an open fire except as provided in COMAR 26.11.07.03
through COMAR 26.11.07.05.
v) COMAR 26.11.09.05 - Visible Emissions
A.(2) Areas III and IV. Mattawoman may not cause or permit the
discharge of emissions from any fuel burning equipment, other than
water in an uncombined form, which is visible to human observers.
w) COMAR 26.11.09.07 - Control of Sulfur Oxides From Fuel Burning
Equipment
This requirement is applicable only to equipment burning diesel fuel
which includes the emergency generator and the firewater pump.
Mattawoman may not burn, sell, or make available for sale any fuel
with a sulfur content by weight in excess of or which otherwise
exceeds 0.3 percent (0.3%) for distillate fuel oils.
x) COMAR 26.11.09.08B(1)(a) – NOX Standards for Fuel Burning
Equipment
Mattawoman may comply with the NOX emission limits in COMAR
26.11.09.08B(1)(c) or the applicable NOX requirements in COMAR
26.11.09.08C - J.
y) COMAR 26.11.09.08E - Fuel Burning Equipment with a Rated Heat
Input of 100 MMBTU/hr or Less
This requirement is applicable to the auxiliary boiler and fuel gas
heater. Requires Mattawoman to annually conduct a combustion
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analysis for each installation and requires operators conducting the
analyses to attend operator training programs every three years.
z) COMAR 26.11.09.08G - Control of NOX Emissions for Major
Stationary Sources, Requirements for Fuel-Burning Equipment with
a Capacity Factor of 15 Percent or Less, and Combustion Turbines
with a Capacity Factor Greater than 15 Percent
This requirement is applicable to the combustion turbines, the
emergency generator and the fire pump engine. Requires that
Mattawoman, as the owner/operator of a CT with a capacity factor
greater than 15%, shall meet an hourly average NOX emission rate of
not more than 42 parts per million (ppm) when burning gas (dry
volume at 15% oxygen) or to meeting applicable PSD limits, whichever
is more restrictive. Requires Mattawoman, for fuel-burning equipment
with a capacity factor of 15% or less, to annually certify the capacity
factor of the equipment to MDE-ARMA in writing, and if the
equipment operates for more than 500 hours during a calendar year, to
conduct a combustion analysis and optimize combustion for that
equipment.
ab) COMAR 26.11.15 and COMAR 26.11.16 - Toxic Air Pollutants and
Procedures Related to Requirements for Toxic Air Pollutants
Requires Mattawoman to determine the applicability of the TAPs
requirements and perform facility-wide air quality analyses, if
applicable. This is a state-only enforceable requirement.
ac) COMAR 26.11.17.03B(3)a, COMAR 26.11.17.03B(1)-(7) –
Nonattainment Provisions for Major New Sources and
Modifications, General Conditions
Requires Mattawoman to meet the reasonable further progress
requirements in §173(a)(1)(A) of the Clean Air Act by satisfying the
conditions in COMAR 26.11.17.03B(1)-(7), including obtaining
emission reductions (offsets) of the same pollutant from existing
sources in the area of the proposed source, whether or not under the
same ownership, at a minimum ratio of 1.3 to 1 for sources of NOX and
VOCs in Prince George’s County, Maryland.
ad) COMAR 26.11.28-Clean Air Interstate Rule Authority
Mattawoman is required to comply with all applicable requirements of
the Clean Air Interstate Rule (CAIR). Mattawoman is subject to the
allowance requirements in CAIR and is required to apply for these
allowances by March 15 of the year following the start of operation.
ae) COMAR 26.11.36 - Distributed Generation
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The emergency diesel generator is required to meet all applicable
Distributed Generation requirements, including, but not limited to, the
following regulations:
i. Mattawoman shall not operate the emergency generator except for
emergencies, testing, and maintenance purposes. [COMAR
26.11.36.03A(1)]
ii. Mattawoman shall not operate the emergency diesel generator
engine for testing and engine maintenance purposes between 12:01
a.m. and 2:00 p.m. on any day on which MDE-ARMA forecasts that
the air quality will be a code orange, code red, or code purple
unless the engine fails a test and engine maintenance and a re-test
are necessary. [COMAR 26.11.36.03A(5)]
af) COMAR 26.09-The Regional Greenhouse Gas Initiative (RGGI)
Requires Mattawoman to participate and adhere to the requirements
of COMAR 26.09. An initial CO2 Budget Permit will be issued in
conjunction with the Part 70 permit. Mattawoman is required to
submit an initial CO2 budget permit application 12 months before the
date on which the CO2 budget source commences operation. This is a
state-only enforceable requirement.
4.6.3
Maryland Toxic Air Pollutants (TAPs) Analysis
Sources of Toxic Air Pollutant (TAP) emissions in Maryland must comply
with COMAR 26.11.15 and 16. The evaluation begins by classifying the
pollutant as either a Class I or Class II TAP. Class I TAPs, which are
known, probable, or potential human carcinogens, are listed in COMAR
26.11.16.06.
The regulations allow for sources to be evaluated to determine if they can
be classified as a small quantity emitter as listed COMAR 26.11.15.03B(3).
For Class I TAPs, a source is considered a small quantity emitter if the
TAP emission rates are less than or equal to 0.5 lb/hr and 350 lb/yr and
the short-term (1-hr and 8-hr) and long-term screening levels are greater
than 200 μg/m3 and 1 μg/m3, respectively. In addition for Class II TAPs, a
source is considered a small quantity emitter if the emission rate is less
than or equal to 0.5 lb/hr and the short-term screening level is greater
than 200 μg/m3. Screening levels for Class I and II TAPs can be found on
the MDE’s website at:
http://www.mde.maryland.gov/programs/permits/airmanagementper
mits/toxicairpollutantregulationdocuments/pages/index.aspx.
If a source does not meet the definition of a small quantity emitter, the
second step is to determine the allowable emission rate (AER) for the TAP.
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If the maximum premise-wide emission rate of a TAP is less than the
calculated AER, then the TAP would be in compliance with the ambient
impact requirement. For stack sources with no downwash, the annual
(lb/yr) and hourly (lb/hr) AER are calculated by dividing the long term
screening level (μg/m3) by 0.0006 and dividing the short-term screening
level 62.5. For non-stack sources or sites where downwash can occur, the
annual (lb/yr) and hourly (lb/hr) AER are calculated by dividing the long
term screening level (μg/m3) by 0.00274 and dividing the short-term
screening level by 279. MDE provided a sample TAPs demonstration,
including a small quantity generator and AER example, at
http://www.mde.state.md.us/programs/Permits/AirManagementPermi
ts/ToxicAirPollutantRegulationDocuments/Documents/enforce.pdf.
The TAPs regulation in COMAR 26.11.15 do not apply to fuel burning
equipment, therefore, emissions of TAPs from the CT/HRSGs, auxiliary
boiler, fuel gas heater, emergency generator, and fire pump engine are not
subject to the regulation. Emissions of TAPs from the cooling tower, if
present, need to be addressed.
PPRP and MDE-ARMA requested that Mattawoman address the
applicability of the TAPs regulation to emissions from the cooling tower.
Mattawoman’s response to PPRP Data Request No. 6-4 indicated that
water from the Piscataway WWTP facility, to be used in the cooling tower,
did not contain any detectable concentrations of priority pollutants,
according to water samples taken to support the NPDES permit for the
WWTP facility. Therefore no TAPs are expected to be present. After
review of the effluent analysis provided by Mattawoman for the
Piscataway WWTP, two analytes with MDE screening levels were
discovered. These compounds are ammonia and phosphorus. While
these compounds are not Class I TAPs, PPRP investigated whether these
compounds could potentially be emitted from the cooling tower in excess
of the applicable AERs. Table 4-45 shows the TAP screening thresholds
and allowable emission rates for ammonia and phosphorus. Table 4-46
presents the worst case emission rate of both of these pollutants from the
cooling tower, using the worst-case analysis for each pollutant provided
in the WWTP effluent analysis. The emissions presented in Table 4-46 are
lower than the AER for ammonia and phosphorus in Table 4-45, which
means that emissions of TAPs are in compliance with the requirements of
COMAR 26.11.15, and no further analyses are necessary.
MD PPRP
4-121
Table 4-45
TAP Screening
Thresholds
and Level
Allowable
Emission
Rates Rate
MDE TAP
Screening
Allowable
Emission
(µg/m 3 )
TAP
Ammonia
Total Phosphorus
Table 4-46
1-hour
8-hour
243.78
174.13
(lb/hr)
Annual
1.01
1-hr
8-hour
0.87
0.62
0.004
Cooling Tower Worst-Case Ammonia and Phosphorus Emission
Rates
TAP
Maximum
Maximum
WWTP Analysis
Emission Rate
g/L
0.00512
0.00122
lb/hr
2.31E-03
5.50E-04
Ammonia
Total Phosphorus
Cooling Tower
Recirculating Water Flow
Rate (gal/min):
Drift Loss Rate:
180,000
0.0005%
Emissions Calculation:
lb Ammonia/gal =
0.00512
𝑔
𝑙𝑏
∗0.002205
𝐿
𝑔
0.26417 𝑔𝑎𝑙/𝐿
𝑙𝑏
lb Ammonia/hr = 4.27𝐸 − 05
MD PPRP
𝑔𝑎𝑙
= 4.27E − 05
∗ 180,000
𝑔𝑎𝑙
𝑚𝑖𝑛
4-122
lb
gal
𝑚𝑖𝑛
∗ 60
ℎ𝑟
∗ 0.0005% = 0.0023 lb/hr
5.0
ANALYSIS OF OTHER ENVIRONMENTAL IMPACTS
5.1
IMPACTS TO BIOLOGICAL RESOURCES
5.1.1
Overview
Environmental impacts of the proposed construction and operation of the
generation facility, associated linear facilities, and substation on biological
resources include potential impacts to aquatic resources; rare, threatened,
or endangered species; wetlands; and vegetation. Cumulatively, the
Project will directly impact approximately 40 acres of forest, 6 acres of
forested wetland, 4 acres of emergent wetland, and more than 1 acre of
stream and water body habitat. Potential impacts related to the
construction and operations on the Project Site are discussed in Section
5.1.2. Section 5.1.3 focuses on the impacts to environmentally sensitive
areas along the linear feature corridors and substation, including an
assessment of cumulative regional impacts.
5.1.2
Project Site
5.1.2.1
Surface Waters and Aquatic Resources
A tributary of Mattawoman Creek, wetlands, and a stormwater pond are
located on the Project Site. Potential impacts to surface waters from site
preparation and plant construction activities include erosion and
sedimentation associated with site grading, material placement, and
access road improvements. The facility will be located on areas of the Site
that are currently open land or gravel road. The facility layout was
updated in Mattawoman’s January 2015 Supplemental Filing, and limits
of site disturbance include 53.19 acres of open land and 0.27 acres of pond
as illustrated in Figure 5-1.
According to Mattawoman’s CPCN application, erosion and
sedimentation impacts will be controlled and minimized through the use
of Best Management Practices (BMPs) and a detailed stormwater
management system (SWM) and erosion and sediment control plan
(Mattawoman, 2013, Section 4.3, p. 4-4). The SWM plan for the Site was
submitted to and approved by the Prince George's Soil Conservation
District, which is included as Appendix A-5 of Mattawoman’s 2013 CPCN
application. Stormwater runoff from the Site will be collected in
constructed trenches to an existing SWM pond onsite. Silt fences and
other system components of a stormwater management plan will be
implemented, minimizing stormwater impacts to surface waters. In
MD PPRP
5-1
addition, Mattawoman indicated that it will comply with the
requirements of MDE’s General Permit for Stormwater Associated with
Construction Activity, which includes the development and
implementation of a Stormwater Pollution Prevention Plan (SWPPP) for
construction activities (Mattawoman, 2013, Section 4.3, p. 4-5).
Figure 5-1
Limits of Disturbance for Site Plan
Source: Mattawoman Response to PPRP Data Request No. 12-15, February 24, 2015,
Attachment 12-15-1
To ensure that impacts to surface water and aquatic resources are
minimized, PPRP recommends licensing conditions requiring compliance
with Maryland’s Stormwater Design Manual and the MDE sediment and
erosion control guidelines during construction for water quality control.
Additionally, Mattawoman should comply with Prince George’s County’s
new Watershed Protection and Restoration Program (WPRP). PPRP also
recommends that a Spill Prevention, Control and Countermeasure (SPCC)
Plan be prepared and implemented to ensure adequate protection of
surface waters during construction. See Section 5.6.4 for further details on
stormwater management for the Site.
5.1.2.2
Wetlands
Mattawoman anticipates that there will be no significant impacts to the
onsite wetlands or the unnamed tributary to Mattawoman Creek as a
result of facility construction or operation (Mattawoman, 2013). Although
the site disturbance plan indicates that wetland areas will be avoided
MD PPRP
5-2
(Figure 5-1), indirect impacts to forested wetlands on and adjacent to the
Site will need to be minimized through approved BMPs and detailed
SWM and erosion and sediment control plans that meet all county and
State requirements. No surface water withdrawals will be necessary for
the Project. Potential impacts resulting from dewatering are discussed in
Section 5.2. Erosion and sediment control measures will need to be
installed prior to commencement of construction activities and monitored
to protect surface water quality. A Joint Wetlands and Waterways Permit
Application will be required to be submitted to MDE and the U.S. Army
Corps of Engineers (USACE).
5.1.2.3
Vegetation and Land Cover
Based on information provided in the Mattawoman CPCN application
(Mattawoman, 2013), site clearing and construction activities will occur in
previously disturbed vegetation communities, including open land and
gravel roads. An existing M-NCPPC approved Tree Conservation Plan
for the Site from the previous land owner required 8.65 acres of
afforestation and 7.66 acres of woodland preservation. Construction
activities should avoid these areas. The construction of the generator lead
line will also require the clearing of approximately 0.94 acres of forest
clearing along the northwestern edge of the site along Brandywine Road
(see Figure 5-1). Mattawoman has prepared a Forest Conservation Plan for
the site (Electronic Link provided in Appendix G of the January 2015
Supplemental Filing). PPRP recommends licensing conditions that will
protect forests, streams and wetlands, including maintaining maximizing
native vegetation on the banks of the unnamed tributary to Mattawoman
Creek and any afforestation or protected areas in the Tree Conservation
Plan for the Site.
5.1.2.4
Primary impacts of construction activities on local wildlife resources
include the temporary and permanent displacement of species from the
construction area due to noise, traffic, and human presence and the
permanent loss or alteration of habitat. Wildlife, such as grassland birds
that use the open meadow habitat, will be affected by the permanent loss
of habitat resulting from the construction and operation of the Project.
Forested areas on or adjacent to the Project Site contain Forest Interior
Dwelling Bird habitat. Populations of many Forest Interior Dwelling Bird
Species (FIDS) are declining in Maryland and throughout the eastern
United States (see Section 5.1.3.4 on Green Infrastructure and FIDS, and
Site E in Section 5.1.3.6).
MD PPRP
5-3
It is possible that rare, threatened and endangered (RTE) habitat is present
on the Site and appropriate consultations with Wildlife and Heritage
Service (WHS) must be conducted if any such habitat or species are
encountered during construction. WHS has determined that there are
records for RTE species documented in close proximity to the Project Site
that could potentially occur on the Site itself, where appropriate habitat is
present (WHS 2014). These RTE species documented occurrences include
the State-threatened Buxbaum’s Sedge (Carex buxbaumii), Sandplain Flax
(Linum intercursumz), and Racemed Milkwort (Polygala polygama), and the
State-endangered Midwestern Gerardia (Agalinis skinneriana), which are
known to occur along the northern segment of proposed gas pipeline in
the CSXT ROW or near Brandywine Receiving Station. Mattawoman
conducted additional surveys in September and October 2014 (Appendix
E of the January 2015 Supplemental Filing). The DNR WHS has accepted
the findings of the rare species survey report, which indicated that no rare
species were observed in the Mattawoman project areas surveyed. The
report also stated that surveys for the spring blooming sedge, Carex
buxbaumii (State Threatened), would be conducted. WHS supports this
additional survey work, and recommended that this survey be done the
first week of June 2015. PPRP recommends licensing conditions that
protect FIDS habitat and any RTE species habitat found on site.
5.1.3
The linear facilities required for the proposed Project are generally
collocated along existing infrastructure such as roads, railroads, and
transmission line corridors, with the exception of areas of new ROW
proposed for the gas pipeline: the Mattawoman Creek Crossing, and the
almost one-mile segment that parallels the main channel of Jordan
Swamp. Additionally, the proposed substation site is comprised of
predominately upland forest, and contains wetlands and headwaters of
Piscataway Creek. These areas are discussed in Sections 5.1.3.5, and are
identified as Site F, I, and K in 5.1.3.6.
The proposed reclaimed water pipeline will mostly be constructed under
existing roads and their right of ways, and within disturbed areas of the
Site. Based on the updated design plans, construction of the reclaimed
water pipeline will affect 6.46 acres of upland forest, 0.23 acres of
herbaceous wetland, 0.11 acres of forested wetlands, and 0.5 acres of
ditches, streams, or waterbodies (January 2015 Supplemental Filing, ERD
p.3-50). Most of the route was previously disturbed for road construction,
and impacts from excavating, placing the pipe, and reconstructing the
road surface are expected to be temporary. At culvert crossings along the
water pipeline route, installation will be done using either jack and bore
MD PPRP
5-4
or horizontal directional drilling (HDD), pending final engineering and
review of individual crossings (January 2015 Supplemental Filing).
Mattawoman plans to use standard BMPs to minimize impacts to
wetlands and waterways and to restore them to preconstruction
conditions once the pipeline has been installed. Subsequently, the
permanent maintenance easement will be routinely mowed or cut to
prevent root growth that could be damaging to the pipeline. PPRP
recommends no mowing in the permanent ROW within 100 foot buffer
zones around these stream crossings and associated wetlands.
The proposed construction ROW for the gas pipeline will vary in width
from 75 feet, where it will be constructed in new areas, to a 65-ft-wide
temporary construction corridor and a 25-ft-wide permanent corridor
through the PEPCO right-of-way, 60 feet in the SMECO easement, and 40
feet in wetland areas. Mattawoman indicated that these disturbance
estimates could potentially change depending on final ROW use
agreements. Based on these ROW widths, construction of the natural gas
pipeline will impact approximately 16 acres of upland forest, 5.82 acres of
wetland forest, 3.66 acres of herbaceous wetland, and 0.4 acres of stream
(January 2015 Supplemental Filing). Temporary impacts from vegetation
clearing, temporary excavation of wetland soils, and ground disturbance
from construction vehicles will account for most of the disturbance, with
the exception of 14 acres of forested habitats, including 2.7 acres of
forested wetlands in the permanent maintenance easement that will be
converted to emergent or scrub/shrub wetlands.
Trees will not be allowed to be reestablished in the PEPCO ROW or in
Mattawoman’s permanent easement in order to minimize potential for
damage to pipe integrity from deep-rooted, woody vegetation. These
areas will be routinely mowed or cut (Response to PPRP Data Request No.
8-6, Exhibit 8-6-3, Section 4.1.2, p. 43). Such plans raise concerns, because
the loss or functional downgrading of wetlands requires mitigation under
Maryland's Non-Tidal Wetlands Act, in proportion to the amount of
wetland function lost, and mowing in wetlands is not an acceptable
maintenance practice. PPRP recommends no mowing in the permanent
ROW within 100 foot buffer zones around these stream crossings and
associated wetlands.
Mattawoman’s proposed generator lead line and the SMECO 69-kV line
are located east of the CSXT railroad tracks for the entire lead line route,
with the exception of the area north/northeast of the PEPCO 500-kV line,
where the SMECO 69-kV line turns west at the intersection with the
PEPCO 500-kV line. The PEPCO 230-kV line that interconnects the
Brandywine project to the Burches Hill substation is located on the west
MD PPRP
5-5
side of the CSXT railroad tracks. Mattawoman is negotiating an
agreement with SMECO to relocate SMECOS’s 69-kV sub-transmission
line 39 feet (ft) east of its current location within the SMECO easement.
Mattawoman will purchase the additional ROW, and clear vegetation in
this corridor for the SMECO line and pay to have the line rebuilt. The
eastward shift will be made with respect to the north/northeast segment
of the lead line route to the crossing of the PEPCO 500-kV line. Nineteen
transmission poles are proposed to be located along the generator lead
line route; the poles will be approximately 140 ft high, and the spans
between them will be between 700 and 900 ft long.
Construction of the generator lead line, as proposed, would impact
approximately 12 acres of upland forest, 1.31 acres of wooded hedgerow,
0.02 acres of forested wetland, and 0.24 acres of herbaceous wetland.
Mattawoman states that this area will be permanently maintained as open
land to meet North American Electric Reliability Corporation (NERC)
guidelines (April 2015 Substation Supplemental Filing). PPRP
recommends reducing the clearing by 20 feet along the eastern edge of the
new 69-kV SMECO ROW, given that a second circuit will not be
constructed concurrently with the Mattawoman generator lead line. PPRP
also recommends that HDD be used under the 500 kV crossing, if feasible,
and tree clearing near the headwaters of Picataway Creek at the substation
site is minimized. Constructing the proposed substation and the tie-in a
the terminus of the generator lead line, at PEPCO’s 230 kV Burches Hill to
Talbert transmission line, will require a permanent loss of approximately
5 acres of upland forest, and 0.02 acre of forested wetland. Building the
substation in a more open area to minimize forest loss, and wetland and
stream impacts is also recommended. Mattawoman stated in their April
2015 Supplemental Filing that they were unable to obtain the property
rights to use PEPCO’s 230-kV right-of-way for a portion of the substation.
Our analysis of Mattawoman’s proposed linear features has identified 11
particularly sensitive areas (see Figure 5-2 for general locations) that are
described in more detail in Section 5.1.3.6. Specific resource impacts are
described in Sections 5.1.3.2 through 5.1.3.5. The pipeline will traverse
several parcels of State of Maryland property that are included in
Cedarville State Forest, which will require additional evaluation and
easement conditions regarding use of the land. Although the pipeline will
nominally be within a Pepco transmission line corridor, it will entail
significant construction ground disturbance, loss of forest habitat, and
affect the future use of the property. Mattawoman is in the process of
obtaining an easement agreement with the State that specifies the
permitted disturbances, protections, and appropriate mitigation for the
loss of use of state property. Approval of the easement agreement by the
Board of Public Works is required before construction can proceed.
MD PPRP
5-6
Figure 5-2. Proposed Reclaimed Water and Natural Gas Pipeline Route and the Eleven Environmentally Sensitive Areas
MD PPRP
5-7
5.1.3.1
Streams
Construction and maintenance of the linear facilities and their associated
rights-of-way (ROWs) will affect freshwater streams through trenching,
loss of vegetation and shading, bank erosion and sedimentation during
construction, and herbicide contamination during maintenance activities.
Long-term effects of increased water temperature due to clearing, erosion,
and runoff from maintenance treatments also elicit concern. These effects
can be reduced with alternative construction techniques such as
horizontal directional drilling (HDD) and good maintenance practices.
In total, the proposed reclaimed water and natural gas pipelines, and
generator lead line cross 11 mapped streams (Figure 5-2) plus several
smaller tributaries and headwaters drainages. The crossings are located
upstream of several stream segments classified as Tier II waterways,
including Mattawoman Creek, Piscataway Creek, Wolf Den Branch,
Jordan Swamp, and Zekiah Swamp Run, and will cause direct impacts to
0.9 acres of streams, ditches, and waterbodies (January 2015 Supplemental
Filing). Tier II waters are defined by the Maryland Department of the
Environment (MDE) as high quality streams where water quality is better
than the minimum standards specified by State water quality standards.
In order to maintain this conditions, direct impacts to Tier II streams
require an anti-degradation review by the State (COMAR 26.08.02.04).
Sensitive stream crossings include areas A-D and F-J shown in Figure 5-2
and described in detail in Section 5.1.3.6. At this time, construction details
concerning stream crossings are not available from Mattawoman,
although it is expected that they will propose using open trenching in
most areas.
Any development in the Mattawoman Creek watershed is of concern to
the State of Maryland. As noted on the Department of Natural Resources
Fisheries Service web pages
(http://dnr2.maryland.gov/fisheries/Pages/FHEP/mattawoman.aspx):
Mattawoman Creek, a 30 mile long tributary to the Potomac River,
is located within Prince George's and Charles Counties and
supports a diverse, high quality aquatic ecosystem. In fact,
Mattawoman Creek Watershed (encompassing 94 square miles) is
ranked 8th out of the 137 watersheds in Maryland for freshwater
stream biodiversity and is one of the most productive spawning
areas for anadromous (shad and herring) and a diverse tidal fish
community. Furthermore, Mattawoman Creek is a well-known area
prized for its largemouth bass fishery, drawing high-profile
MD PPRP
5-8
tournaments and anglers from all over the country throughout the
year. Mattawoman Creek is filled with abundant and rare natural
resources, offering residents and visitors the chance to observe a
stunning environment that once surrounded the entire Chesapeake
Bay. Unfortunately the Chesapeake Bay, including Mattawoman
Creek, is deteriorating due to increased development.
Particular concern attends projects that increase the amount of impervious
surface in the watershed, fragment forest habitat, or directly affect stream
condition and water quality. Such impacts are best avoided by protecting
undeveloped areas of the watershed and giving the highest level of
protection to stream areas where RTE species habitat is present (Part 3:
Summary of recommendations for non-tidal streams in the Mattawoman
Creek watershed, p. 74 in The Case for Protection of the Watershed
Resources of Mattawoman Creek, The Interagency Mattawoman
Ecosystem Management Task Force, March 15, 2012). . For these reasons,
PPRP recommends that the pipeline crossing of Mattawoman Creek and
the associated forest wetlands be accomplished through HDD, with
minimal surface disturbance or vegetation removal.
The Wicomico River/Zekiah Swamp Run System is a State-designated
Scenic River. Maryland's Scenic and Wild Rivers System Act (Section 8401 of the Natural Resource Article) recognizes that many rivers or
portions of rivers in Maryland, and their tributaries and watersheds,
possess outstanding scenic, geological, ecological, historical, recreational,
agricultural, cultural, and other similar values. The State's policy is "…to
preserve and protect the natural values of these rivers, enhance their
water quality, and fulfill vital conservation purposes by the wise use of
resources within their surrounding environment." According to the Act,
each unit of State and local government is required to take whatever
action is necessary to protect and enhance the qualities of a designated river.
To fulfill this intent, PPRP recommends that Mattawoman use enhanced
BMPs during construction at all stream and tributary crossings that affect
the Zekiah Swamp System (Sites G, H, and I on Figure 5-2), use HDD
wherever feasible at these sites, and restore and maintain the crossings in
the best possible ecological condition through long-term integrated
vegetation management plans. Mowing in the permanent ROW should
not occur within 100 foot buffer zones around these stream crossings and
associated wetlands. The almost 1-mile long new ROW segment parallel
to Jordan Swamp (Site I) will have particularly detrimental effects, and
rerouting along the existing PEPCO ROW using HDD beneath Jordan
Swampor an alternative route for the last approximately 1-mile segment
following Poplar Hill Road and Gardiner Road would be preferable.
MD PPRP
5-9
PPRP also recommends that Mattawoman use HDD at Site J on Figure 5-2,
the portion of the generator lead line that crosses under PEPCO’s 500 kV
line at the tributary of the Mattawoman Creek. Enhanced BMPs to reduce
impacts to the headwaters of Piscataway Creek should also be used at Site
K, the proposed Substation for the project.
In general, at all the streams crossed by the proposed pipeline,
appropriate BMPs should be used to control erosion and sedimentation
that might otherwise be caused by construction activities, including the
design and placement of runoff-control features implemented in a
stormwater management plan. Stream banks and stream bottoms should
be restored to their previous condition and function, supporting local
biological communities and providing protection to downstream Tier II
streams. Additionally, restored areas should be monitored and treated for
several years to ensure the re-establishment of sustainable native species
communities in and adjacent to the streams.
5.1.3.2
Construction and maintenance of linear facilities and their associated
rights-of-way (ROWs) primarily affect RTE species through the
elimination of the species themselves or through the degradation of their
habitat. To avoid impacts, preliminary research is conducted prior to the
construction of a proposed project in order to investigate the occurrence of
both State and federally listed RTE species in or near the Site. If any
potential habitat for RTE species is identified, then field surveys are
required to determine whether populations of those species are present.
Impacts to sensitive species can usually be avoided or minimized by
redesigning or relocating the project, applying Best Management Practices
(BMPs), or limiting the time of construction to specific seasons.
The water and gas pipeline routes cross several streams located in the
Piscataway Creek, Mattawoman Creek and Zekiah Swamp watersheds.
The generator lead line crosses a tributary of Mattawoman Creek, and the
substation site is located upstream of a Tier II segment and headwaters of
Piscataway Creek. There are two State-threatened fish species in
Piscataway watershed: the American Brook Lamprey and the Comely
Shiner. The State-threatened Flier is known to occur the Zekiah Swamp
watershed. PPRP recommends minimal surface disturbance or vegetation
removal at stream crossings in these sensitive watersheds, in conjunction
with MDE permit requirements.
The DNR WHS identified two RTE plant species known to occur within
the northern segment of this gas pipeline route, in the existing CSX
MD PPRP
5-10
railroad ROW: the State-listed threatened Racemed Milkwort (Polygala
polygama) and State-listed threatened Buxbaum’s Sedge (Carex buxbaumii)),
and seven RTE plant species in close proximity to the proposed route
including the four species documented near Brandywine Receiving
Station discussed in Section 5.1.2.4 (WHS 2014). The State-rare Deciduous
Holly (Ilex decidua) and the State-endangered Kidneyleaf Grass-ofParnassus (Parnassia asarifolia) are known to occur within close proximity
to the part of the gas pipeline route that goes through State land at
Cedarville State Forest associated with a branch of Wolf Den
Branch/Zekiah Swamp Run. Also occurring in close proximity to the gas
pipeline route, near Jordan Swamp, are multiple records for State rare
Primrose Willow (Ludwigia decurrens).
Surveys for RTE species, performed by ECT on behalf of Mattawoman in
May/June 2014, did not identify any RTE plant species in either the
reclaimed water or natural gas pipeline routes. However, recommended
survey times for several of the plant species were between August and
October. ECT conducted addition RTE surveys in September and October
of 2014. The WHS has accepted the findings of the rare species survey
report, which indicated no rare species were observed in the Mattawoman
project areas surveyed. The report also stated that surveys for the spring
blooming sedge, Carex buxbaumii (State Threatened), would be conducted.
WHS supports this additional survey work, and recommended that this
survey be done the first week of June 2015. No RTE species are known to
occur in the generator lead line route, Mattawoman submitted a request
for the new substation site to WHS in April 2015, and ECT will conduct a
listed species survey of the revised substation site in June 2015 (April 2015
Substation Supplemental Filing, p.8). Following recommendations made
by WHS for the protection of RTE plant species, a management plan for
any RTE species potentially affected by construction will be required.
Mitigation of any impacts to RTE species will also be required.
The proposed reclaimed water and natural gas pipelines are located
within Biodiversity Conservation Network areas (BIONET) and areas that
have been identified as potential habitat for FIDS by the DNR WHS (WHS
2014). The proposed Project will widen the existing gaps in FIDS habitat
within the PEPCO/SMECO transmission line ROW and create new gaps
in areas of new ROW. The almost 1-mile long new ROW segment parallel
to Jordan Swamp (Site I) will create a nearly 0.5 mile long new 75-foot
wide ROW through sensitive forested areas surrounding the swamp
(Response to PPRP Data Request 8-6, Exhibit 8-6-1, Sheet 13-14).
Evaluating rerouting along the existing PEPCO ROW using HDD beneath
Jordan Swamp or considering an alternative route following Poplar Hill
Road and Gardiner Road was recommended by PPRP. At a minimum,
MD PPRP
5-11
PPRP recommends reducing the width of the permanent ROW, using of
HDD under WSSC and streams connected to WSSC, stream bank and
bottom restoration, wetlands vegetation management, special protection
of Tier II streams, and at least three years of post-construction monitoring
in this sensitive area.
5.1.3.3
Wetlands
Construction and maintenance of the Mattawoman linear facilities and
their associated ROWs will affect wetlands and their associated buffers in
a variety of ways. Overall the project will result in about 10 acres of
wetland impacts (April 2015 Substation Supplemental Filing).
Additionally, disturbing soil in upland areas may allow runoff to convey
loosened soil into streams and associated wetland areas. Construction
noise and dust could disrupt nearby wetland habitat; therefore,
construction in wetlands areas should be avoided during critical
reproductive periods for the plants and animals that make up the
wetlands’ ecosystems. Protective matting should be used to avoid
destruction of wetland areas. After construction, it is particularly
important to use integrated vegetation management techniques that avoid
using inappropriate herbicides in or near wetland areas and to refrain
from using mowers or other equipment directly in wetlands areas and
their buffers.
Mattawoman states that the only permanent impacts that will result are
the permanent conversion of 2.82 acres of forested wetland in the
permanent maintenance easement. Following construction, these areas
will be maintained as emergent or scrub/shrub wetlands, and there will
be no net loss of wetlands, just a change in wetland type according to
Mattawoman. PPRP concludes that, while there may be no overall
decrease in wetland area, the functionality of the wetland would be
drastically changed owing to the removal of the larger shade trees that
will thereby impact the wildlife and understory plant community.
Forested wetlands also provide benefits such as soil stabilization.
Approximately 0.02 acre of forested wetland within the substation site
that will need to be permanently filled (April 2015 Substation
Supplemental Filing, p.10). Mattawoman proposes to mitigate this
permanent loss of the filled wetland by creating wetlands along the same
drainage, outside the proposed limits of disturbance, at a ratio approved
by MDE, and protect stream channels during construction to minimize
sediment erosion. However, the streams on the site are the headwaters of
a Tier II segment of Piscataway Creek. The loss of 4.6 acres of upland
forest in the headwaters area cannot be addressed by onsite mitigation.
Forests and forested wetlands in the headwater drainage area of a stream
MD PPRP
5-12
enhance downstream conditions by sequestering excess nutrients,
increasing groundwater absorption, reducing stream temperatures and
runoff flows, in addition to providing necessary food resources to aquatic
biota.
Wetlands are prevalent along the proposed reclaimed water and natural
gas pipeline routes and the revised substation site, and are associated with
the stream systems. Particularly sensitive wetland areas include Sites A
through K highlighted in Figure 5-2, and described in detail in Section
5.1.3.6. The proposed natural gas pipeline crosses the headwaters of
Mattawoman Creek, two tributaries to Wolf Den Branch, two tributaries
to Zekiah Swamp Run, and three headwater ravines that drain into Jordan
Swamp. Both Zekiah Swamp Run and Jordan Swamp are designated as
Wetlands of Special State Concern (WSSC). WSSC wetlands provide
habitat for RTE species; are unique natural areas; or contain ecologically
unusual natural communities and receive enhanced legal protection under
COMAR 26.23.06. At the time of this writing, Mattawoman has not
provided specific construction details regarding the headwater crossings
of the WSSC, but plans to trench a majority of the gas pipeline. PPRP
recommends that restored wetlands and reforested areas be monitored to
ensure the establishment of sustainable native species communities
including RTE species, where present. To further minimize impact to
wetlands, PPRP recommends that Mattawoman consider HDD to
construct the gas pipeline under Mattawoman Creek, and also under
Jordan Swamp in the existing PEPCO ROW, as an alternative to creating a
new 1-mile long ROW in the forested headwaters of Jordan Swamp.
5.1.3.4
Forests, Green Infrastructure, and FIDS
DNR has established land conservation strategies to preserve and restore
the State’s ecological health. One of DNR’s programs, the Green
Infrastructure (GI) Assessment is designed to identify and map large areas
of contiguous forest habitat hubs and narrower natural corridors that
connect the hubs and allow movement among faunal and floral
populations. Additional information on this program can be found at
http://www.dnr.state.md.us/greenways/gi/gi.html. GI and FIDS
habitat along the proposed gas pipeline ROW is shown in Figure 5-3.
The GI Network is important to the State because the size of forest patches
correlates directly with the species of plants and animals that inhabit them
and the diversity that the patch of forest can support. The protection of
FIDS is also crucial. High quality FIDS habitat is comprised of
predominantly mature hardwood or mixed hardwood-pine forest in the
vicinity of the ROW. Forests with greater amounts of edge (i.e., habitats
MD PPRP
5-13
less than 300 feet from the outer edge of the forest) tend to have larger
populations of generalists and invasive species.
Additionally, DNR’s Wildlife and Heritage Service's Natural Heritage
Program (NHP) has mapped and ranked terrestrial and freshwater areas
throughout the State for biodiversity conservation. A specific set of
criteria is used to identify the most irreplaceable species and habitats, as
well as the habitats that concentrate larger numbers of rare species,
thereby forming a statewide Biodiversity Conservation Network
(BIONET).
The proposed reclaimed water and natural gas pipeline corridors lie
almost entirely within GI and FIDS habitat as shown in Figure 5-3, and the
gas pipeline will widen the existing gaps associated with the
PEPCO/SMECO transmission line ROW. As proposed, the gas pipeline
will require approximately 16 acres of upland forest, and 5.82 acres of
forested wetlands to be cleared. Constructing the generator lead line,
substation, and the tie-in will impact approximately 17 acres of forest and
0.04 acre of forested wetland. DNR requires mitigation for the clearing
and cutting of forests under the Forest Conservation Act (FCA). In
addition, this area is located in a Green Infrastructure Hub, where PPRP
recommends a post-construction vegetation management plan in order to
minimize impacts to the watershed. To minimize impacts to FIDs habitat,
the removal or disturbance of forest habitat during April-August, the
breeding season for most FIDS, is not recommended. This seasonal
restriction may be expanded to February-August if certain early nesting
FIDS (e.g., Barred Owl) are present. PPRP would prefer that Mattawoman
use HDD to construct the gas pipeline at the Mattawoman Creek and
Jordan Swamp crossings, or consider an alternative route for the last
approximately 1-mile segment following Poplar Hill Road and Gardiner
Road.
MD PPRP
5-14
Figure 5-3
MD PPRP
Green Infrastructure and FIDS Habitat along the Proposed Mattawoman Reclaimed Water
and Natural Gas Pipeline Corridors and the Generator Lead Line Right-Of-Way
5-15
5.1.3.5
Regional Cumulative Impacts
Sensitive watersheds are often near their capacity to withstand additional
stressors, and even small impacts may push them over thresholds into a
more degraded or less resilient state. Because of the close linkages
between watershed ecosystems in the area surrounding the proposed
Mattawoman Project and linear facilities, local impacts may also cascade
throughout the region. It is therefore necessary to assess impacts at a
cumulative, regional-scale. Quantitative measures such as acres of forest
lost or miles of stream affected are inadequate for this task, because it is
difficult to develop a common scale or baseline. However, the sensitivity
of each resource to disturbance can be characterized, mapped, and
combined in a Geographic Information System (GIS) into an overall
depiction of regional development constraints. The areas affected by the
proposed Project can be evaluated in terms of this baseline.
To create the constraints map, the sensitivity of each resource to
disturbance was ranked from 1 to 9. The features considered include:
floodplains, streams and wetlands, public lands, land cover, wildlife
habitat, agriculture, historical sites, slope, and zoning. For each feature
type, background areas where development would not affect the resource
represented are rated 1 and resource areas that are physically unusable for
construction or in which development is legally prohibited are rated 9.
These ranked feature maps are then combined in a way that calculates the
overall sensitivity to development at each point using the same scale.
Each additional resource or legal protection that is present at a point
increases the combined sensitivity level in a graduated way, so that the
output map captures the cumulative effects.
Figure 5-4 shows the results of this analysis for the entire region. The
numerical scale used in developing the map has been converted to three
colors (Table 5-1) that show the sensitivity to or availability for ROW
construction at each point. What is most obvious from this map is the
dominance of restricted (green) areas; low impact areas suitable for
construction (yellow and ivory) are scattered within a background matrix
of sensitive or unavailable areas. This is reflective of the pattern of
existing development, the large areas of wetlands and forest, and the
many protected sensitive resource areas that characterize the region. In
the northwestern part of the area, intensive residential development and
zoning drive the restrictions, while in the less developed southern and
eastern sections, protected forests, streams, and wetlands are more
important.
MD PPRP
5-16
Figure 5-4 Cumulative Environmental Constraints Map
MD PPRP
5-17
Table 5-1
Cumulative Constraint Map Scale
Color
Numerical
Range
Included
How Area Would be Affected by a ROW
Ivory
1 to 3.5
ROW development will have little to no
impact other than transient effects that can
be controlled or easily addressed.
Yellow
3.5 to 6.5
There will be permanent disturbance that
should be minimized and may require
mitigation.
Green
6.5 to 9
Severe impacts requiring replacement,
unacceptable destruction of unique
protected resources, or areas unsuitable
for construction because of ecological,
physical, or legal constraints.
The proposed Mattawoman Site itself is not in a high-impact area. The
map shows, however, why the development of the associated linear
facilities raises significant environmental concerns. The Site is located at a
point where three watersheds abut, potentially affecting the headwaters of
them all. There are nearly continuous high-impact regions to the west of
this area.
The high-impact regions to the south of the proposed linear facilities are
also extensive, with limited low-impact routing options through the
headwaters of the Mattawoman Creek and Zekiah Swamp watersheds.
The transmission line ROWs through this area are mostly in the highimpact zone, and not designed or sited to accommodate pipeline ground
disturbance, so using them does not significantly alleviate the expected
impacts.
In addition, most of the proposed Mattawoman natural gas pipeline will
lie in the western edge of PEPCO’s Oak Grove-Talbert-Morgantown
transmission line ROW, which runs just east of the Project location in the
Mattawoman watershed at the headwaters to Mattawoman Creek, and
then through the Zekiah Swamp watershed. The Regional Transmission
Organization, PJM, has indicated that PEPCO must rebuild the
transmission line in this ROW by June 2018. The PEPCO project would
entail removal and replacement of towers, requiring significant
disturbance from construction and staging areas and heavy equipment
access. Because this ROW traverses the Mattawoman and Zekiah Swamp
watersheds, including portions of the Cedarville State Forest, any
MD PPRP
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construction activity will affect multiple sensitive resources within the
same watershed and general time frame as the Mattawoman Project.
One such location along the Mattawoman natural gas pipeline where
multiple impacts to resources at one location can have severe downstream
impacts is the crossing of the headwaters of the Mattawoman Creek
mainstem. The proposed pipeline route, including the forested wetland
just southeast of the Mattawoman Site itself (Figure 5-2, Site F) crosses the
Creek upstream of a protected Tier II stream segments and involves a
forested wetland complex, some of which will be converted to herbaceous
wetland after construction is complete. Figure 5-5 shows Mattawoman’s
proposed gas pipeline ROW at the Mattawoman Creek crossing, which
will run adjacent to the proposed gas pipeline route for the Keys Energy
Center facility. The construction of the pipelines via trenching, as
proposed in their respective CPCN applications, would result in the
clearing of 2.44 acres of forested wetlands in the immediate vicinity of
Mattawoman Creek crossing. PPRP prefers that forested wetland
disturbance be minimized in this area through the use of HDD, if feasible
and approved by MDE, and by positioning Mattawoman’s gas pipeline
beneath the railroad at a 45-degree angle rather than the proposed 90degree crossing (See Figure 5-5).
MD PPRP
5-19
Figure 5-5
Mattawoman Creek Area Showing the Location of the Proposed Natural
Gas Pipeline Route
Note: Figure 5-5 shows the highlighted location of the proposed Mattawoman
gas pipeline route (ROW and disturbance area highlighted in purple), a portion
of which will be adjacent to the proposed Keys Energy Center gas pipeline
(construction ROW outlined in yellow).
This area is also Sensitive Species Project Review Area (SSPRA),
containing known occurrences of the State-threatened racemed milkwort
and Buxbaum’s sedge. It also is possible habitat for at least two additional
RTE plants and contains FIDS habitat, as indicated in a letter from MD
DNR Wildlife and Heritage Service dated July 29, 2014, although none
were detected during the RTE Species Surveys conducted in September
and October of 2014. Surveys will be conducted in June of 2015 for the
sedge, Carex buxbaumii (State Threatened). This area is in a Green
Infrastructure Hub, where PPRP recommends a post-construction
MD PPRP
5-20
vegetation management plan in order to minimize impacts to the
watershed.
As the natural gas pipeline approaches the tie-in to the Dominion
Pipeline, it turns to the southeast and parallels the main channel of Jordan
Swamp, which is designated as a Tier II stream segment in the Zekiah
Swamp Scenic River watershed (see Figure 5-2, Site I and Figure 5-6enlargement of the Jordan Swamp area near the southern end of proposed
gas pipeline route). For almost one mile between the PEPCO 230-kV
ROW and the Dominion Pipeline, the proposed route passes through
several wetland/stream complexes that drain directly to Jordan Swamp,
only 500 to 800 feet from the boundary of the Jordan Swamp WSSC,
designated as such due to unique habitat value the presence of RTE
species. This area is also a designated SSPRA.
Figure 5-6
Map of Environmentally Sensitive Areas of Jordan Swamp
Note: Figure 5-6 provides a map of the environmentally sensitive areas of Jordan
Swamp near the southern end of the proposed natural gas pipeline route,
including Tier II waters, Green Infrastructure and FIDS habitat.
MD PPRP
5-21
The consultation letter with DNR Wildlife and Heritage Service dated July
29, 2014 states that there are multiple records for the State-rare primrose
willow in close proximity to the pipeline route near Jordan Swamp, and
that this area also contains designated FIDS habitat, although no RTE
species were found during subsequent surveys (January 2015
Supplemental Filing, Appendix E). In addition, this area is located in a
Green Infrastructure Hub, where PPRP recommends a post-construction
watershed. This proposed span of pipeline will also include
approximately 8-10 acres of forest clearing, requiring consultation with
the Forest Service and mitigation under the Forest Conservation Act.
This clearing will create a ROW parallel to the drainage of the Swamp,
affecting the hydrology of the downstream watershed in multiple
locations along the route. Multiple impacts to ecological resources in one
relatively small area can have far reaching impacts downstream, affecting
both the Tier II stream segment and the environmentally sensitive Zekiah
Swamp Scenic River downstream. To reduce these effects, PPRP
recommends that Mattawoman minimize its proposed temporary and
permanent ROW widths and use HDD below streams and wetlands in
order to minimize surficial disturbance within this ecologically important
watershed. A route that avoids this area completely, or that uses HDD
below the Swamp along the existing ROW, is preferable to creating a new
ROW.
The center of the region, both geographically and ecologically, is the
Zekiah Swamp watershed (enhanced watershed outline on Figure 5-4).
The Mattawoman Project will affect the natural resources of this
designated Scenic River watershed through miles of gas pipelines across
headwaters streams and drainages. These impacts will be added to
impacts from other power facility construction, including the nearby Keys
Energy Center and the Talbert-Morgantown transmission line. Without
mitigation, there will be permanent impacts that include the loss of tens of
acres of Green Infrastructure forest, displacement of wetlands soils and
conversion of dozens of forested wetlands to herbaceous wetlands,
alteration of numerous stream bottom and bank areas, and loss of use of
State parkland. Each individual impact diminishes the "natural values" of
the river system that are protected by the Scenic River Act, and in total
they degrade the system instead of improving it as called for by the Act.
MD PPRP
5-22
5.1.3.6
Environmentally Sensitive Sites
Site A – Multiple stream crossing at the intersection of Livingston Road
and Accokeek Road
(Streams 5, 6, 7, and 8)
Site Description: This area encompasses the crossing of three small
tributaries (easternmost tributary is crossed two times) to Piscataway
Creek by the reclaimed water pipeline. The area also contains FIDS
habitat.
PPRP Concerns:
1. FIDS habitat
2. Multiple wetland crossings
3. Multiple stream crossings
Recommendations
•
Stream bank and bottom restoration
•
Wetlands vegetation management
•
At least three years of post-construction monitoring
Map Illustration of Site A stream crossing, wetlands, and geometry from revisions of
Figure 11, sheets 17 and 18, Appendix A-1, Response to PPRP Data Request 8-6,
Exhibit 8-6-3
MD PPRP
5-23
Site B – Stream Crossing on Accokeek Road, south of Danville Road
(Stream 4)
Site Description: This area encompasses the crossing of a small tributary
to Mattawoman Creek by the reclaimed water pipeline. This tributary is
directly upstream of a Tier II segment of Mattawoman Creek. The area
also contains FIDS habitat.
PPRP Concerns:
1. FIDS habitat
2. Wetland crossing
3. Stream crossing
4. Upstream of Tier II segment
Recommendations
•
Stream bank and
bottom restoration
•
Wetlands vegetation
management
•
At least three years
of post-construction
monitoring
•
Special protection
of Tier II stream
Map Illustration of Site B stream crossing, wetlands, and geometry from revisions of Figure
11, sheets 10 and 11, Appendix A-1, Response to PPRP Data Request 8-6, Exhibit 8-6-3
MD PPRP
5-24
Site C – Crossing of Burch Branch on Accokeek Road, Southwest of
Branch Avenue
(Stream crossing is not numbered in Mattawoman CPCN application,
Figure 11)
(Burch Branch) to Piscataway Creek by the reclaimed water pipeline. A
small lake (Ruth Lake) is located just south (upstream) of the crossing.
This tributary is upstream of a Tier II segment of Piscataway Creek. The
area also contains a Green Infrastructure Hub and FIDS habitat.
PPRP Concerns:
1. FIDS habitat
2. Green Infrastructure
3. Wetland crossing
4. Stream crossing
Recommendations
• Stream bank and bottom restoration
• Wetlands
vegetation
management
• At least three
years of postconstruction
monitoring
• Special
protection of
Tier II stream
Map Illustration of Site C stream crossing, wetlands, and
geometry from revisions to Figure 11, sheet 6, of Appendix A1, Response to PPRP Data Request 8-6, Exhibit 8-6-3
MD PPRP
5-25
Site D – Crossing of Timothy Branch on Brandywine Road, Southeast of
Branch Avenue, at the Brandywine Area Recreation Area
(Stream 1)
(Timothy Branch) to Mattawoman Creek by the reclaimed water pipeline.
This tributary is upstream of a Tier II segment of Mattawoman Creek. The
area also contains a Green Infrastructure Hub and FIDS habitat.
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
Recommendations
•
Stream bank and
bottom restoration
•
Wetlands
vegetation
management
•
At least three years
of postconstruction
monitoring
•
Special protection
of Tier II stream
Map Illustration of Site D stream crossing, wetlands, and
geometry from revisions to Figure 11, sheet 2, of Appendix A1, Response to PPRP Data Request 8-6, Exhibit 8-6-3
MD PPRP
5-26
Site E – Mattawoman Project Site
Site Description: This area encompasses the location of the Mattawoman
Site, which includes a small tributary to Mattawoman Creek. This
tributary is upstream of a Tier II segment of Mattawoman Creek. The area
also part of a Green Infrastructure Hub and FIDS habitat.
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
Recommendations
•
Stream bank and bottom restoration
•
Wetlands vegetation management
•
•
Special protection of Tier II stream
•
Vegetation Management plan for Green Infrastructure area and any
mitigation areas planned for site
Map Illustration of Site E, the Mattawoman Project Site,
highlighting area of disturbance, Mattawoman Response to PPRP
Data Request No. 12-15, February 24, 2015, Attachment 12-15-1
MD PPRP
5-27
Site F – Crossing of Mattawoman Creek at the CSXT rail line, south of
Brandywine Road
(Stream 1)
Site Description: This area encompasses the crossing of the headwaters
of Mattawoman Creek, upstream of the Tier II segment, by the natural gas
pipeline. The area also contains a Green Infrastructure Hub and FIDS
habitat, as well as a Sensitive Species Project Review Area (SSPRA).
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
5. Upstream of Tier II
segment
6. Sensitive Species
Project Review Area
Recommendations
•
Stream bank and
bottom restoration
•
Wetlands vegetation
management
•
At least three years of
post-construction
monitoring
•
Special protection of
Tier II stream
•
Vegetation
Management plan for Green Infrastructure area
•
Protection for RTE species
MD PPRP
Map Illustration of Site F stream crossing, wetlands,
and geometry from revised, Response to PPRP Data
Request 12-22, Exhibit 12-22-3
5-28
Site G – Multiple stream crossings in PEPCO 500 kV ROW, in
Cedarville State Forest at the Prince George’s/Charles County Line, near
Bee Oak Road
(Stream 1)
Site Description: This area encompasses the crossing
by the natural gas pipeline of the two tributaries that are
headwaters of Wolf Den Branch, upstream of the Tier II
segment. Wolf Den Branch is a tributary to Zekiah
Swamp, a Maryland Scenic River. It is also located
upstream of a Wetland of Special State Concern (WSSC).
The area also contains a Green Infrastructure Hub and
FIDS habitat, as well as an SSPRA.
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
6. Sensitive Species
Project Review Area
7. Maryland Scenic River
8. State Land Crossing
9. WSSCS
Recommendations
•
Stream bank and bottom
restoration
•
Wetlands vegetation
management, especially for
WSSC
•
•
•
Vegetation Management plan for Green Infrastructure area
•
•
Coordination with State Park
MD PPRP
Map Illustration of Site G stream crossing,
wetlands, and geometry from revised Figure
10, of Appendix A-1, Response to PPRP Data
Request 8-6, Exhibit 8-6-3 (sheets 7 and 8).
5-29
Site H – Multiple stream crossings in PEPCO 500 kV ROW, in
Cedarville State Forest, near St. Peter’s Church Road, Havensbrook
Drive and Holly Spring Road
Site Description: This area encompasses the crossing by the natural gas
pipeline of the two tributaries that are headwaters of Wolf Den Branch,
upstream of the Tier II segment. Wolf Den Branch is a tributary to Zekiah
Swamp, a Maryland Scenic River. It is also upstream of a Wetland of
Special State Concern
(WSSC). The area also
contains a Green
Infrastructure Hub and FIDS
habitat, as well as an SSPRA.
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
segment
6. Sensitive Species Project
Review Area
8. WSSC
Recommendations
•
Stream bank and
bottom restoration
•
Wetlands vegetation
management,
especially for the
WSSC
•
•
•
•
•
Coordination with State Park
MD PPRP
Map Illustration of Site H stream crossing, wetlands,
and geometry from revised Figure 10, of Appendix A-1,
Response to PPRP Data Request 8-6, Exhibit 8-6-3
(sheets 9 and 11).
5-30
Site I – Wetland Crossing upstream of Jordan Swamp
(Wetlands 30 and 31, Stream 5)
Site Description: This area encompasses the crossing by the natural gas
pipeline of several wetland/stream complexes that are in the headwaters
of Jordan Swamp, a Wetland of Special State Concern (WSSC). The
crossing is also upstream of several Tier II stream segments in Zekiah
Swamp, a Maryland Scenic River. The area also contains a Green
Infrastructure Hub and FIDS habitat, as well as an SSPRA.
PPRP Concerns:
1. FIDS habitat
3. Wetland crossing
4. Stream crossing
6. Sensitive Species Project
Review Area
8. WSSC
9. Forest Clearing
10. Potential RTE species
habitat
Recommendations
•
Stream bank and bottom
restoration
•
Wetlands vegetation
management
•
At least three years of postconstruction monitoring
•
Special protection of Tier II
stream
•
Vegetation Management
plan for Green
Infrastructure area
•
MD PPRP
Map Illustration of Site I stream crossing,
wetlands, and geometry (update to Figure
10, sheet 14, Appendix A-1, Mattawoman
Supplemental CPCN Filing 2014; (DNR
wetland layer including WSSC and wetland
buffers highlighted in green).
5-31
Site J – Stream Crossing-Tributary of Mataponi Creek at PEPCO 500 kV
crossing
Site Description: This portion of the proposed generator lead line route
passes under the existing PEPCO 500 kV line, which crosses the lead-line
route in an east/west direction. A tributary to Mattaponi Creek also
crosses the PEPCO ROW at this location. Mattaponi Creek and its
tributaries are headwaters streams for the Patuxent River, a state
designated Scenic River, protected under Maryland's Scenic and Wild
River Act. The proposed construction plan for this area will require
clearing 100 linear feet of forested riparian buffer along the Creek.
PPRP Concerns:
1. FIDS habitat
2. Green
Infrastructure
3. Stream crossing
4. Forest Clearing
Recommendations
•
Stream bank and
bottom
restoration
•
At least three
years of postconstruction
monitoring
•
Vegetation
management
plan for riparian
corridor
MD PPRP
Map Illustration of Site J stream crossing,
wetlands, Mattawoman Supplemental CPCN
Filing 2015).
5-32
Site K – Project Substation
Site Description: This proposed substation site is located on Cherry Hill
Crossing Rd, and is adjacent to PEPCO’s 230 kV transmission line.
Approximately 6 acres of land will be used for the substation and the tiein of the generator lead line. Development of the site will result in a
permanent loss of approximately 4.6 acres of upland forest, 1.3 acres of
open land, and 0.02 acre of forested wetland, which are the headwaters of
a Tier II stream segments of Piscataway Creek. The area also contains
Green Infrastructure and FIDS habitat.
PPRP Concerns:
1. FIDS habitat
2. Wetlands
3. Streams
segment
5. Forest Clearing
Recommendations
•
Sediment and
Erosion Control
Plan for site
•
Stream bank and
bottom restoration
•
Wetlands vegetation
management
•
Mitigation for forest
clearing per FCA
requirements
•
•
•
MD PPRP
Map Illustration of Project Substation
(Mattawoman Substation Supplemental
Environmental Review Document CPCN Filing
April 2015)
5-33
5.1.4
General Recommendations
Maryland has adopted policies and regulations that ensure no net loss of
wetlands and forest areas, and no degradation of high quality streams
(e.g., Nontidal Wetlands Act, Forest Conservation Act, and Scenic and
Wild River Act). Moreover, Maryland’s Scenic and Wild River Act
instructs State and local agencies to use any means necessary to not only
protect but also enhance the qualities of the designated river systems
including the Wicomico River and Zekiah Swamp. Avoidance is the most
effective approach to protecting sensitive biological resources. Where
avoidance is not feasible, minimizing disturbances through the utilization
of enhanced best management practices (BMPs) and alternative
construction techniques such as horizontal directional drilling (HDD)
under stream or wetlands is recommended. Minimization, however, does
not negate the need for mitigation of the disturbances to ecologically
sensitive areas.
The disturbance to wetlands, streams, and forests from the gas pipeline
construction in the extremely sensitive Zekiah Swamp watershed will
have to be mitigated, preferably with in kind replacement within the
watershed itself. The Scenic and Wild Rivers Act reinforces and gives
added strength to the non-tidal wetlands and forest conservation
regulations, and overrides any utility exemptions. PPRP therefore
recommends that licensing conditions be imposed on any CPCN issued
for construction of the Mattawoman Project and linear facilities that
require:
•
The total acreage of trees removed for construction of the power
plant and its associated linear facilities and substation shall be
mitigated in the amount determined by the Maryland Department
of the Natural Resources (MDNR) Forestry Service according to the
FCA specifications.
•
All clearing of forest from wetlands areas that will be retained as
herbaceous wetlands shall be mitigated by restoration of an equal
or greater amount of forested wetland within the same watershed.
Any wetland area that is completely drained or destroyed shall be
mitigated according to the provisions of the Nontidal Wetlands Act
and as approved by MDE.
•
Managed conversion of the cleared wetland areas to herbaceous
wetlands containing sustainable populations of native species
similar to those found in existing wetlands in the watershed.
Monitoring and treatment of the wetlands as necessary, for a
MD PPRP
5-34
period of several years, to ensure this result and to prevent a
takeover by invasive species.
•
No disturbance in WSSC or their 100-foot buffers, as determined by
MDE and the Maryland Department of Natural Resources (DNR),
by using Horizontal Directional Drilling (HDD), with approval
from MDE, to avoid any vegetation disturbance or removal.
•
Construction to be avoided during critical reproductive periods for
the plants and animals of the wetlands ecosystem.
•
All stream bottoms and banks that are trenched during
construction will be restored to their original contours and soil
composition, stabilized, and monitored for a period of years to
ensure, and address as necessary, any erosion, scouring, or other
deterioration.
•
100-foot no-mow zones to be established around all wetlands and
streams within the pipeline ROWs. Any necessary vegetation
removal in these areas will be by hand or by MDE-approved
herbicide treatment.
•
Minimization of impacts on forest interior dwelling species (FIDS)
and other native forest plants and wildlife by time-of-year
restrictions on disturbance of forest habitat during April-August,
the breeding season for most FIDS, which may be expanded to
February-August if certain early nesting FIDS species are present.
•
Completion of all surveys of known RTE plant species in the
vicinity of the Project prior to construction, and the protection of
RTE species and habitat through avoidance and monitoring during
construction.
MD PPRP
5-35
5.2
IMPACTS TO GROUND WATER
This section describes the impacts to groundwater quantity associated
with construction activities, and impacts to groundwater quality
associated with operation of the power plant.
5.2.1
Construction Impacts
5.2.1.1
Dewatering Estimate
Dewatering of groundwater during construction of footers, foundations
and subgrade structures will require a groundwater appropriation permit
if dewatering exceeds 30 days or an average of 10,000 gallons per day, in
accordance with COMAR 267.17.06.03.B(3). The withdrawal of
groundwater for dewatering requires a new appropriation issued by the
Maryland PSC through this CPCN proceeding.
This section describes the estimated amount of groundwater that will be
withdrawn for dewatering, and evaluates the potential impacts from
dewatering to: 1) the Quaternary Upland Deposits (also referred to locally
as the Brandywine Formation), 2) surrounding groundwater users, and 3)
surface water and wetlands. In addition, the section describes the results
of the evaluation of potential impacts to the ongoing remediation at the
Brandywine DRMO Superfund Site, and discusses the Project’s interaction
with the institutional controls that have been identified as part of the
remedy for the Brandywine DRMO site.
The presence of the water table at a depth of six to seven feet below
ground surface (bgs) (measured in September 2014 in on-site monitoring
wells) in the area of the proposed power block creates the need to dewater
to support the construction of selected subgrade structures. The depth to
the water table is expected to be as high as five feet bgs during high water
table conditions in the spring season. According to Mattawoman’s
Response to PPRP Data Request No. 11-2, the current power block design
will require dewatering to facilitate construction of seven individual
subgrade structures, as follows.
•
Four subgrade structures are associated with the circulating water pipe
(CWP) and circulating water forebay in the cooling tower. These four
subgrade structures will require excavation to depths between 19 and
20 feet bgs and dewatering to five feet below that depth.
•
Three plant features were identified as requiring dewatering to
support construction: steam turbine (STG FDN), steam turbine
MD PPRP
5-36
generator/step up transformer (STG XFMR), and combustion turbine
generator/step up transformer (CTG Aux XFMR). These three
subgrade structures will require excavation to depths between 7 and 8
feet bgs and dewatering to two to three feet below that depth.
In Mattawoman’s Response to PPRP Data Request No. 11-2, the estimated
amount of dewatering that will occur during construction was calculated.
The method used by Mattawoman to estimate the amount of construction
dewatering was based on the Dupuit-Forcheimer equation for steady-state
flow in an unconfined aquifer (Power, 1992). The equation includes the
estimates of the excavation length, width, and depth, saturated thickness
to be excavated, and hydraulic conductivity of the geologic materials
within the dewatered zone, as well as the duration of the dewatering
event.
Mattawoman provided hydraulic conductivity values based on nine
individual short-term aquifer tests conducted in five separate monitoring
wells (Mattawoman Response to PPRP Data Request 10-2). The hydraulic
conductivity values obtained from the short-term aquifer tests were based
on the Cooper-Jacob method and ranged from 0.3 to 13.2 ft/day. The
average value is approximately 4 ft/day. The hydraulic conductivity of 4
ft/day was used to calculate the dewatering amount and is considered to
be a reasonable estimate for the sands and gravels found in the Upland
Deposits present at the Site. Further, the 4 ft/day value is similar to
values obtained from aquifer testing conducted in the Upland Deposits on
the nearby Brandywine DRMO site (URS 2006). PPRP independently
verified the calculations used by Mattawoman to determine hydraulic
conductivity based on the results of the short-term aquifer tests
(Appendix E).
Table 5-2 below presents a summary of the dewatering amount
determined by Mattawoman in their response to PPRP Data Request 11-2,
and verified by PPRP.
MD PPRP
5-37
Table 5-2
Dewatering Calculation
Aquifer
Aquifer Radius of
Saturated Thickness Equiv.
Width Dewatering Depth to
Avg
Hydraulic
Radius of
Q
Well - Ae Conductivity - Influence (ft)
to
W
Depth
Base of Depth to Thickness design
Length - L
Depth - D Duration
H
Dewatering
(ft)
(ft)
Aquifer
WT
K (ft/d)
- Ro
(ft)
(ft)
(days)
No.
Excavation
Q (gpd) (gpm)
(ft)
1
CW Forebay
80
40
20.5
75
20.5
35
5
30
9.5
36
4
267
37,990
26
2
CW Pipe - 2 pipes
400
32
19
120
19
35
5
30
11
72
4
286
53,080
37
3
CW Pipe- 1 pipe
140
18
19
45
19
35
5
30
11
32
4
246
35,872
25
4
CW Pipe at CT
260
18
19
75
19
35
5
30
11
44
4
258
41,189
29
Annual Total (gal)
Annual Avg (gpd)
Peak Month Total (gal)
Peak Monthy Daily Rate (gpd)
5
6
7
STG FDN
STG XFMR
CTG & Aux XFMR
140
60
60
70
75
100
8
7
7
30
30
30
5
5
5
35
35
35
5
5
5
30
30
30
25
25
25
63
43
49
4
4
4
Total
Peak Month
withdrawn
Total
design
Withdrawn
(gal)
(gal)
2,849,257
1,139,703
6,369,642
1,592,410
1,614,252
1,076,168
3,089,174
1,235,670
13,922,325
38,143
5,043,951
168,132
119
40,469
28 1,214,071
99
30,724
21 921,731
106
33,921
24 1,017,615
Annual total (gal)
3,153,417
Annual Avg (gpd)
8,639
Peak Month Total (gal)
Peak Month Pumping Rate (gpd)
Annual Avg Pumping Rate (gpd)
Peak Month Pumping Rate (gpd)
Table 5-2 shows 17,076,000 gallons as the total estimated volume of
groundwater to be removed during construction dewatering from seven
subgrade structures based on the Dupuit-Forcheimer equation (13,922,325
gallons from the first four subgrade structures plus 3,153,417 gallons from
the next three subgrade structures). The annual average daily dewatering
rate of approximately 46,783 gallons per day (gpd) (17,076,000 gallons/365
days) is calculated based on the need to dewater all seven subgrade
structures and normalizing the dewatering amount over an entire year in
accordance with MDE WMA methods to calculate the average annual
amount of the appropriation.
Mattawoman provided the estimated duration to dewater each unit based
on the estimated time to excavate and construct the foundation of each
structure. If each subgrade structure were dewatered sequentially, the
dewatering would take 13.5 months. The time periods listed in Table 5-2
for the duration of the dewatering are considered by Mattawoman to be
conservative. Additionally, the location of the subgrade structures
requiring dewatering are in close proximity to each other, and therefore,
will likely be dewatered concurrently. In fact, Mattawoman indicates that
the STG FDN structure will be constructed concurrently with the CW
Pipe-2 Pipe structure and will not need additional dewatering. Thus for
the purpose of assessing impacts, the period of dewatering is assumed to
last 12 months.
To confirm the reasonableness of the construction dewatering estimate,
Mattawoman estimated the dewatering flow rate using the alternative
method (Section 5.3 and Appendix D, October 3, 2014 Trihydro Report,
MD PPRP
5-38
1,214,071
921,731
1,017,615
3,153,417
105,114
46,783
273,246
submitted in Mattawoman’s response to PPRP Data Request 10-2). The
alternative approach is based on two equilibrium equations used to
estimate dewatering rates presented in Groundwater and Wells (Driscoll,
1986). The equations calculate the equilibrium dewatering rates based on
the dimensions (an effective radius) of the dewatered structure, the radius
of influence for the proposed dewatering scenarios, and the dewatering
depth requirements and hydraulic conductivity for the aquifer. The first
equation provides an estimate of the dewatering rate required to produce
a certain drawdown, and the second equation can be used to estimate the
dewatering rate from one side of a trench per unit length. The first
equation yields a higher flow rate and is typically more representative of
the early dewatering flow rates, while the latter equation yields a lower
flow rate that is more representative of the later time
(maintenance/sustaining) flow rate. The resulting average annual
dewatering rate for the first four subgrade structures on Table 5-2 is 27,044
gpd, which is 40 percent less than the dewatering rate calculated using the
Dupuit-Forcheimer equation. This approach is more reflective of how
dewatering will occur compared to the calculation based on the DupuitForcheimer equation.
Mattawoman requested an appropriation of 52,077 gpd average daily use
for a dewatering withdrawal (Appendix F, October 3, 2014 Trihydro
Report, submitted in Mattawoman’s response to PPRP Data Request 10-2).
This amount is based on the dewatering of the first four structures listed
on Table 5-2, plus an addition of between 0.9 to 4.7 gpm for each structure
to account for a 100 percent capture of a two inch per hour rainfall event,
and the application of a 25 percent contingency. Even though the three
subgrade structures listed at the bottom of Table 5-2 were added in
Mattawoman’s response to PPRP Data Request 11-2, Mattawoman
indicated that the requested appropriation was sufficient because of
multiple conservative contingencies and the low probability that all seven
subgrade structures would be dewatered simultaneously. Mattawoman
requested a month of maximum use amount of 230,400 gpd which was
based on the assumption that dewatering occurs simultaneously for one
month at all four structures.
Based on the dewatering amounts calculated in Table 5-2, MDE WMA
recommends the following appropriation amounts for construction
dewatering, which are somewhat higher than the amounts requested by
the applicant:
•
Average Daily Use. The annual average water requirement is 60,000
gpd; and
MD PPRP
5-39
•
Month of Maximum Use. During the month of maximum use, the
allocated quantity is an average of 275,000 gpd.
The average daily use amount of 60,000 gpd (58,479 gpd and rounded) is
based on the application of a 25 percent contingency value to the 46,783
gpd calculated in Table 5-2 to account for uncertainties associated with the
estimates at this stage of the construction process, as well as potential
rainfall that falls into the excavation. The dewatering value proposed by
MDE WMA is conservative because of the overlap of dewatering that will
occur in the individual excavations during construction and decrease in
higher initial withdrawal rates once the initial cone of depression is
established at each subgrade structure.
The addition of the 25 percent contingency value to the average daily use
number is further supported when the amount of precipitation that falls
on the excavations is considered. Annual rainfall in Prince George’s
County measured in Upper Marlboro is 43.24 inches per year (NOAA,
2014). There is uncertainty associated with the amount of rainfall that will
evaporate versus the amount that will be captured in the excavation.
Assuming two-thirds of the rainfall evaporates and one-third is captured
in the excavated areas, the 14 inches spread over the estimated three acres
of excavation area will generate about 760,000 gallons per year or 2,100
gpd over a 365-day period. The 2,100 gpd is much less than the 11,696
gpd added by the 25 percent contingency, demonstrating the level of
conservancy added by the contingency because there is low probability
that all seven excavations will be dewatered simultaneously.
The month of maximum use value of 275,000 gpd is based on the
conservative assumption that all seven excavations listed in Table 5-2
need to be dewatered concurrently within 30 days (8,197,368 gallons/30
days, rounded). The 25 percent contingency was not added to the month
of maximum use value.
Groundwater in excavations will be controlled through a series of shallow
dewatering wells or trenches with sump pumps designed to lower the
water table and control groundwater flowing into excavations until
construction below the water table is complete. Mattawoman is proposing
to collect the water generated during dewatering, temporarily store water
in tanks, and once the water quality is verified, discharge the water to the
stormwater pond (Mattawoman Response to JBA Data Request 1-3). The
effluent from the stormwater pond will be regulated by a general
stormwater permit for construction, which includes dewatering effluent
(Mattawoman Response to PPRP Data Request 8-1).
MD PPRP
5-40
5.2.1.2
Impact Evaluation
The total estimated annual withdrawal associated with the dewatering
appropriation is 22,000,000 gallons if dewatering occurs at a rate of 60,000
gpd for a full year. Dewatering the water table by 22,000,000 gallons per
year (gpy) could lead to four potential impacts to ground and surface
water quantity, albeit limited to one year:
•
Impacts to the amount of water in the aquifer;
•
Impacts to off-site groundwater users;
•
A reduction in the amount of groundwater that discharges to
streams and wetlands; and
•
Impacts to the Brandywine DRMO remediation.
Distance-Drawdown Evaluation
A conservative estimate of potential distance-drawdown values associated
with the short-term dewatering impacts to other users was determined
using a method developed for drawdown in an unconfined aquifer
(Boulton 1954, 1963). The Boulton method was used to evaluate the
potential short-term withdrawal impacts to off-site users, surface water
and the Brandywine DRMO remediation associated with drawdown
caused by the average annual dewatering rate of 60,000 gpd for a 12month period. For the purpose of determining drawdown impacts, it is
assumed that the groundwater withdrawal occurs at one location. Note
that the Boulton method is very conservative in that it does not account
for recharge from precipitation over a one-year period; such recharge
could mitigate dewatering impacts. Appendix E presents the description,
assumptions and input values used for this method, and the results of the
calculations.
Worst-case impacts from the month of maximum use rate of 275,000 gpd
would occur at the end of the year. The worst-case impacts are calculated
by using the output from the Boulton analysis for 215,000 gpd over a 30day period and adding these results to the drawdown values calculated
for the 60,000 gpd withdrawal. The 215,000 gpd represents the
incremental increase in pumping above the average annual amount of
60,000 gpd.
Table 5-3 presents the results of the distance-drawdown calculations
based on the 60,000 gpd annual average, with the 215,000 gpd incremental
MD PPRP
5-41
increase in pumping occurring in the last month of the year. In addition
to the pumping rate (60,000 gpd) and duration (one year), the distancedrawdown calculations include the hydraulic conductivity and specific
yield values used as inputs. A hydraulic conductivity value of 4 ft/day
and a specific yield of 0.2 were used as input values for the calculated
drawdown shown in Table 5-3. The rationale for using these values is as
follows:
•
Hydraulic Conductivity. The hydraulic conductivity value of 4 ft/day
was discussed above and is based on the results of the on-site single
well pumping tests.
•
Specific Yield. Specific yield measures the volume of water that an
unconfined aquifer releases from storage per unit surface area of
aquifer per unit decline in the water table (Freeze and Cherry, 1979).
Specific yield values cannot be determined from a single well pumping
test. The usual range of specific yields for an unconfined aquifer is
0.01 to 0.30 (Freeze and Cherry, 1979). The rationale for using a value
of 0.2 for the specific yield is based on the visual and grain size
analysis of the aquifer materials (Trihydro Report, Mattawoman’s
response to PPRP Data Request 10-2).
Table 5-3
Distance-Drawdown Calculations for One Year at the
Annual Average Withdrawal Rate and Month of Maximum
Use Rate (Specific Yield = 0.2)
Distance from
Pumping Well
250
500
600
700
800
900
1000
1500
2000
3000
4000
Calculated
Drawdown for
60,000 gpd for
365 days (feet)
11.57
5.05
3.64
2.61
1.85
1.30
0.90
0.11
0.01
0.00
0.00
Calculated
Drawdown for
215,000 gpd for
30 days (feet)
5.15
0.12
0.02
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Total Calculated
Drawdown for 365
days (feet)
16.72
5.17
3.67
2.62
1.85
1.30
0.90
0.11
0.01
0.00
0.00
The distance-drawdown calculations will vary depending on the
hydraulic conductivity and specific yield values used as input values. For
example, use of a higher hydraulic conductivity value will result in a
smaller predicted drawdown at the dewatered excavations, but will cause
the drawdown to propagate outward a further distance. A lower specific
MD PPRP
5-42
yield value results in greater drawdown both at the dewatered excavation
and at distances outward from the excavation. MDE WMA recommends
that a value of 0.1 be used for the specific yield in unconfined aquifers in
Maryland Coastal Plain. The 0.1 value is representative of the sandy silt
and gravel layer that comprises the water table aquifer at the
Mattawoman site. Table 5-4 presents the results of the distancedrawdown calculations based on the 60,000 gpd annual average, and
using a hydraulic conductivity value of 4 ft/day and a specific yield of 0.1.
Table 5-4
Distance from
Pumping Well
250
500
600
700
800
900
1000
1500
2000
3000
4000
Distance-Drawdown Calculations for One Year at the
Annual Average Withdrawal Rate and Month of Maximum
Use Rate (Specific Yield = 0.1)
Calculated Drawdown Calculated Drawdown
for 60,000 gpd for
for 215,000 gpd for
365 days (feet)
30 days (feet)
15.19
12.36
8.14
1.28
6.46
0.44
5.13
0.13
4.08
0.04
3.23
0.01
2.55
0.00
0.71
0.00
0.16
0.00
0.00
0.00
0.00
0.00
Total Calculated
Drawdown for 365
days (feet)
27.55
9.42
6.90
5.27
4.12
3.24
2.55
0.71
0.16
0.00
0.00
Based on the Boulton method, the calculated drawdown after one year is
2.55, 0.16 and 0.00 feet at distances from the dewatered excavations of
1,000, 2,000, and 3,000 feet, respectively. The northern property boundary
is located 2,500 feet from the dewatered excavations. The distancedrawdown values in Table 5.4 will be used to assess impacts to off-site
users and water resources.
Impacts to the Aquifer
The potential for the groundwater withdrawal to impact the unconfined
Upland Deposits was evaluated using a water budget analysis for the site.
The water budget assumes that water into a basin equals water out of the
basin plus any change in storage (i.e., groundwater withdrawal). The
purpose of this evaluation is to ensure the groundwater withdrawal does
not exceed the sustained yield of the aquifer and to protect baseflow to
nearby streams and wetlands.
MD PPRP
5-43
The total average rainfall for the site area is approximately 43.24 inches
per year (NOAA, 2014). MGS determined recharge of 6.8 inches per year
(in/yr) calculated from baseflow records for the nearby Western Branch at
Upper Marlboro for the period 1986-2003 (Andreasen 2007). Using an
annual average rainfall recharge rate of 6.8 in/yr, the dewatering of about
22,000,000 gpy will require an average surface area of about 118 acres (6.8
in/yr/12 inches x 43,560 ft2/acre x 7.48 gallons/ft3 = 185,722 gallons per
acre).
The power block is approximately 20 acres (developed area limiting
recharge) within the larger 88-acre property. Therefore, there will be
insufficient undeveloped surface area available on the property to provide
100 percent of the recharge to the aquifer to replace the groundwater
removed from the area within the power block during dewatering.
However, reducing recharge over a 12 month period will not have a longterm impact to recharge, and recharge to the Upland Deposits will occur
in off-site areas. Thus, no long-term impacts to the amount of recharge
contributed to the aquifer associated with the expected annual dewatering
of 22,000,000 gallons are expected.
Impacts to Off-site Groundwater Users
As discussed in Section 3.2.3, groundwater is a source of potable water for
the residential area in the vicinity of the Mattawoman site. As shown in
Figure 3-4, the majority of the residential wells in the vicinity of the
Mattawoman site are completed in the deeper Aquia and Magothy
aquifers, and would not be impacted by the dewatering that occurs in the
unconfined Upland Deposits. The MDE WMA well permit inventory
indicates that a few of the residences located on Old Indian Head Road
and on Tower Road have wells completed in the Upland Deposits. Based
on the MDE WMA well permit inventory, the residential well completed
in the Upland Deposits closest to the Mattawoman site is located 3,000 feet
from the dewatering area. Complete information regarding the potential
presence of shallow dug wells is not available because many of the
shallow wells were installed before well inventory records were
established. Therefore, there could be additional residential wells
completed in the Upland Deposits in the vicinity of the Mattawoman site.
As shown in Table 5-4, the Boulton distance-drawdown calculations
indicate that no measurable drawdown was calculated to occur at a
distance of 3,000 feet from the dewatering location at the power block
after one year. Therefore, the Boulton method indicates that if these
residences have wells completed in the Upland Deposits, the wells would
not experience drawdown during the year that dewatering occurs.
MD PPRP
5-44
Additionally, the Boulton method is very conservative in that it does not
account for recharge from precipitation over a one-year period and
recharge could mitigate dewatering impacts.
Another potential mitigating condition is that the intervening unnamed
tributary between the point of withdrawal and the potential residential
well locations may serve as a hydraulic recharge barrier, and thereby limit
drawdown. However, it is not certain that the hydraulic connection
between the streams and the surficial aquifer create such a barrier.
Reduction in Baseflow to Streams and Wetlands
Dewatering will extract water from the watershed that contains the
unnamed tributary to Mattawoman Creek and the associated wetland
areas (Figure 5-7). The unnamed tributary to Mattawoman Creek is
located about 1,000 feet from the dewatered excavations. A wetland is
present in the southwest corner of the Mattawoman site at a distance of
500 feet from the dewatering excavations. The distance drawdown values
listed in Table 5-4 indicates that drawdown 1,000 feet from the excavations
could be 2.55 feet, and drawdown 500 feet from the dewatered
excavations could be 9.42 feet after the year of dewatering is completed.
The Boulton calculations suggest that there could be some temporary loss
of baseflow to the unnamed tributary and wetlands during the one year of
dewatering.
MD PPRP
5-45
Figure 5-7
Watershed Boundary for the Unnamed Tributary to
Mattawoman Creek
The impact of the dewatering withdrawal on the stream and wetlands can
also be assessed by comparing the amount of water extracted for
dewatering (22,000,000 gpy) to the total amount of baseflow contributed to
the tributary within the estimated 667 acre watershed. The tributary
receives baseflow from the north and east, which are areas that will not be
affected by the dewatering. The total amount of baseflow contributed by
the watershed is conservatively estimated to be 124 million gpy, based on
the 6.8 in/yr of recharge and the 667 acres area for recharge to occur. (6.8
in/yr/12 inches x 43,560 ft2/acre x 7.48 gallons/ft3 = 185,722 gallons per
acre x 667 acres). The dewatering will remove about 18 percent of the
total estimated annual baseflow into the unnamed tributary during the
one year of construction dewatering.
MD PPRP
5-46
The impacts associated with the loss of 18 percent of the baseflow to the
unnamed tributary to Mattawoman Creek are expected to be temporary
and will be mitigated by the following conditions:
•
Mattawoman indicated that the extracted groundwater would be
placed into the stormwater pond where it will either re-infiltrate
into groundwater or be discharged into the unnamed tributary;
•
The streams will receive baseflow from other areas of the
watershed during construction dewatering and will not be
completely drained;
•
The dewatering impacts will be temporary. After construction
dewatering is complete and the excavations are backfilled, the
elevation of the water table in the Upland Deposits and water to the
stream will be restored.
Impacts to Brandywine DRMO Remediation Program
The Brandywine DRMO Superfund Site is located north of Brandywine
Road. The groundwater beneath and beyond the Brandywine DRMO Site
is impacted by chlorinated volatile organic compounds (VOCs), and has
undergone extensive remediation over the past 20 years to remove the
VOCs from the groundwater. Current conditions at the Brandywine
DRMO site, including the status of the remediation program, current
plume configuration, and groundwater flow directions are described in
Appendix F. As part of the remediation, an institutional control boundary
has been identified (Figure 3-2). Groundwater withdrawal within this
boundary will be prohibited. Construction dewatering at the
Mattawoman site cannot impact the area within the institutional control
boundary or future remediation.
The dewatering at the Mattawoman site will not impact the Brandywine
DRMO remediation. The technical basis for this conclusion is presented in
Appendix F. In summary, potential impacts to the Brandywine DRMO
remediation will not be realized for the following reasons:
•
Calculated drawdown using the Boulton method does not extend to
the Brandywine DRMO institutional control boundary, located 3,000
feet from the dewatering area;
•
The Brandywine DRMO plume has been substantially remediated and
is currently located approximately 3,200 feet from the dewatering area;
MD PPRP
5-47
•
The presence of the unnamed tributary to Mattawoman Creek creates a
hydrologic divide between the dewatering area and the Brandywine
DRMO site; and
•
A slight increase in hydraulic gradients caused by dewatering would
only cause the plume to be drawn towards the dewatering area a short
distance over the one year of dewatering, and after dewatering is
completed the plume boundary would be stagnant.
Even though the potential to impact the Brandywine DRMO remediation
is unlikely, MDE WMA recommends the implementation of a water level
monitoring and mitigation program (described in Section 5.2.4 below)
during the dewatering period to ensure that potential drawdown impacts
do not occur.
5.2.2
Dewatering for Linear Facilities
Mattawoman needs to determine whether dewatering will be conducted
to support the installation of the 8-mile gas and 10-mile reclaimed water
pipelines, and if dewatering is necessary, whether the amount or duration
of dewatering will exceed the amount and duration threshold limits listed
in COMAR 26.17.06.03.B.(3). The information needed to estimate the rate
of dewatering in areas where pipes are placed below the water table,
particularly in areas adjacent to or under streams, includes the following:
•
The estimated length of pipeline segments that will be installed
beneath the water table;
•
An estimate of the depth that the excavations will extend below the
water table (i.e., saturated thickness); and
•
Duration of pipeline construction and average construction
duration of each segment.
Mattawoman’s response to PPRP Data Request 12-31 and 12-32 indicated
that the geotechnical testing and engineering with respect to the reclaimed
water and gas pipelines has not been completed. Further, Mattawoman’s
response to PPRP Data Request 15-5 and 15-6 indicated that the field data
for the two pipelines will be collected in May and June 2015, and based on
the results of the field data, a determination as to whether an additional
groundwater appropriation is necessary will be made by the end of June
2015. Thus there is insufficient time to review the field information and
incorporate the impact evaluation into this document.
MD PPRP
5-48
The proposed 60,000 gpd annual average appropriation for the on-site
construction dewatering will not apply to the pipelines because the
location of dewatering is different. Each location where an appropriation
of water occurs requires notification of surrounding property owners.
Each pipeline construction project is considered by MDE WMA as a
separate construction project for the purpose of evaluating conformance to
the groundwater appropriation requirements. Therefore, if the
dewatering amounts associated with the installation of the gas and treated
effluent pipelines cause the threshold limits in COMAR 26.17.06.03.B.(3) to
be exceeded, Mattawoman needs to submit an application to the PSC to
obtain an amendment to the CPCN to include the pipeline dewatering
amounts.
The request for an amendment to the CPCN should include, but not be
limited to the following: 1) the estimated length of pipeline to be installed
beneath the water table, 2) the estimated depth that excavations will
extend below the water table, 3) the duration those excavations below the
water table will remain open, and 4) a request for a water appropriation
on the form provided by MDE WMA indicating the anticipated average
daily appropriation on an annual basis and the average daily
appropriation during the month of maximum use. The information
supporting the CPCN amendment must also contain a map showing the
locations and property ownership where dewatering will occur, and the
ownership of properties adjacent to where dewatering will occur.
5.2.3
Routine or Accidental Releases to Groundwater
A Spill Prevention, Control, and Countermeasures (SPCC) Plan will need
to be developed and implemented in accordance with EPA requirements
to address refueling, storage and containment of hazardous materials, and
spill cleanup and reporting. Proper implementation of the SPCC Plan will
protect groundwater quality, and prevent accidental releases to
groundwater.
As described in Mattawoman’s response to PPRP Data Request 8-1,
groundwater quality will be protected from the discharge of stormwater
and dewatering effluent into the stormwater management pond. The
MDE 2014 permit guidelines for stormwater permits include a provision
that authorizes the discharge of dewatering effluent from construction
excavations where managed by an appropriate control. Mattawoman will
follow the general permit guidelines and use Best Management Practices
(BMPs) to control dewatering effluent in compliance with the 2011
Maryland Standards and Specifications for Soil Erosion and Sediment
Control. The BMPs to be implemented may include the use of vegetative
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filters and sediment traps. Additionally, Mattawoman is proposing to
collect the water generated during dewatering, temporarily store water in
tanks, and once the water quality is verified, discharge the water to the
stormwater pond (Mattawoman Response to JBA Data Request 1-3).
JBA has raised the concern that the extraction of groundwater during
dewatering will draw impacted water into the excavations from an offsite
source. This potential impact will not be realized because: 1) drawdown is
not projected to occur 3,000 feet offsite; 2) drawdown will be for one year
and not sustained long enough to draw contamination towards the
excavations; and 3) the majority of the groundwater pulled into the
excavations will be drawn from the northeast area, which is forested and
undeveloped. However, MDE WMA recommends that groundwater
quality in the area of the excavations be characterized prior to dewatering
to ensure that the groundwater quality is not impacted and impacted
groundwater is not discharge into the stormwater pond.
5.2.4
Recommendations
MDE WMA recommends that Mattawoman be granted an appropriation
to use groundwater from the Upland Deposits to dewater excavations to
support the construction of selected subgrade features within the power
block. MDE WMA recommends the appropriation be granted with the
following amounts:
•
Average Daily Use. The annual average water requirement is
60,000 gpd from the Upland Deposits (Brandywine Formation); and
•
Month of Maximum Use. The maximum daily water use is 275,000
gpd for the month of maximum
As described above in Section 5.2.1.2, the withdrawal of 22,000,000 gallons
of groundwater over a 12 month period will not have an adverse impact
on the recharge to the aquifer, surface water, off-site groundwater users,
or the remediation of the Brandywine DRMO VOC plume. Drawdown
that will occur due to dewatering will not be significant enough to alter
the direction of groundwater flow, and drawdown effects will be
temporary and reversible after dewatering is complete. Further, the
dewatering rate of 60,000 gpd will likely not be sustainable over the 12
month dewatering period. However, to ensure drawdown impacts are
monitored and mitigated if the analyses presented herein underestimates
the potential drawdown impacts, MDE WMA recommends the
development of a monitoring and mitigation plan to be implemented
during dewatering. The monitoring and mitigation plan should include
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measuring water levels in monitoring wells during construction
dewatering, and if the results of the monitoring indicate a potential for
unacceptable drawdown impacts to occur in connection with
Mattawoman’s construction dewatering, then mitigation measures should
be implemented.
Mattawoman proposed a monitoring plan and mitigation to address
impacts in the Supplemental Direct Testimony of Vilma Brueggemeyer,
Bradley Pekas, and Marianne Horinko. The key elements of the
Mattawoman monitoring plan include (referenced well locations are
shown in Figure 5-8):
•
Monitoring background water levels in the on-site wells, including
a new well (MW-8) installed at the northern property boundary,
during a 30-day period preceding the construction dewatering;
•
Monitoring water levels at wells MW-6, 7 and 8 during dewatering,
and calculating a seven-day moving average using single daily
measurements of water levels. The seven-day moving average is
intended to normalize natural fluctuations in the water table;
•
If water levels in wells MW-6 and MW-7 decrease below threshold
values of 0.25 to 0.5 ft. compared to well MW-8, then mitigation in
the form of either reducing dewatering pumping rates or
adjustment of the construction schedule will be made; and
•
If water levels in wells MW-6 and MW-7 decrease below threshold
values of 0.5 to 1.0 ft. compared to well MW-8 (after initial
mitigation is implemented), then mitigation in the form of
recharging water to create a hydraulic barrier will be implemented.
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Figure 5-8
Existing and Proposed Monitoring Well Locations on the
Mattawoman and Brandywine DRMO Sites
MDE WMA agrees with the need for monitoring during a baseline period
and during construction dewatering, and Mattawoman’s general outline
for triggers and proposed mitigation. However, MDE WMA believes that
additional site-specific hydrogeologic data are needed before a monitoring
and mitigation plan can be fully developed. Therefore, MDE WMA
recommends the following step-wise approach to the development and
implementation of a monitoring plan.
1) Conduct site-specific hydrogeologic studies to determine the
groundwater flow configuration and gradients. As part of this
study, two new monitoring wells should be installed into the
Upland Deposits, one well designated MW-8 to be located on the
northern boundary of the property at Brandywine Road north of
existing well MW-6, and the second well, designated as MW-9, to
be located on the western boundary of the property but north of the
unnamed tributary to Mattawoman Creek (Figure 5-8). Baseline
water level monitoring consisting of synoptic water level
measurements should be conducted in: 1) the two new monitoring
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wells, 2) the existing seven monitoring wells to determine
groundwater flow directions and gradients, and 3) off-site wells
associated with the Brandywine DRMO remediation (if access is
granted by JBA and CSX). Additionally, the baseline monitoring
needs to include the collection of continuous water level
measurements in wells MW-6, MW-7, MW-8 and MW-9 using
transducers for a period of at least two weeks.
2) Conduct baseline groundwater quality monitoring in three existing
monitoring wells completed in the area where dewatering will
occur (MW-1, MW-3 and MW-5). Analyze the groundwater
samples for U.S. Environmental Protection Agency Target
Compound List (TCL) VOCs and SVOCs, and Target Analyte List
Metals.
3) Provide a plan describing the approach for the water level
monitoring (Water Level Monitoring and Mitigation Plan), triggers
for mitigation, and proposed mitigation no later than 180 days in
advance of the initiation of construction dewatering withdrawals.
The Water Level Monitoring and Mitigation Plan shall include the
results of the baseline water level and groundwater quality
monitoring, a determination of the groundwater flow direction and
gradients, and the results of the continuous water level recording.
The Water Level Monitoring and Mitigation Plan shall include: 1)
the proposed locations, frequency and duration of water level
monitoring, including the use of continuous water level
monitoring; 2) a description of the proposed threshold criteria that
if triggered, will require implementation of mitigation measures; 3)
frequency and content of reporting the results of the water level
monitoring; and 4) a description of the proposed mitigation
measures to be implemented if necessary. Proposed mitigation
measures will include at a minimum modifying pumping of
groundwater to reduce drawdown impacts and recharging
recovered groundwater. If recharging recovered groundwater is
proposed, identify any necessary approvals to be obtained from the
MDE Underground Injection Control Program.
4) Provide a plan describing how extracted groundwater will be
managed during the duration of the dewatering, including but not
limited to: 1) obtaining any necessary permits or approvals for
discharge of the extracted groundwater; 2) mitigating any
groundwater quality impacts identified by the baseline
groundwater quality monitoring; 3) containing and characterizing
the quality of the extracted groundwater during the duration of
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dewatering prior to discharge; and 4) mitigating any water quality
impacts identified by the analysis of the water quality samples
during the dewatering prior to discharge.
5) Implement the Water Level Monitoring and Mitigation Plan
concurrent with the initiation of construction dewatering
withdrawals.
The Water Level Monitoring and Mitigation Plan needs to be submitted to
the Brandywine DRMO Superfund Site Tier 1 Project Review Team,
consisting of EPA, MDE, and JBA project managers (Tier 1 Review Team)
for review. MDE will be represented by MDE WMA and MDE Land
Management Administration (LMA). After consulting with Mattawoman,
JBA, MDE WMA and MDE LMA, the EPA and MDE members of the
Project Review Team shall determine whether the proposed Water Level
Monitoring and Mitigation Plan is acceptable. Lastly, if the EPA and MDE
members of the Tier 1 Review team determine that construction
dewatering has adversely impacted groundwater remediation at the
Brandywine DRMO site, even after the Water Level Monitoring and
Mitigation Plan has been implemented, Mattawoman will need to
implement additional mitigation, and if necessary, compensate the United
States Air Force for damages in the event that mitigation is ineffective.
Lastly, MDE WMA recommends that if dewatering associated with the
installation of the gas and treated effluent pipelines causes the threshold
limits in COMAR to be exceeded, Mattawoman should submit an
application to the PSC to obtain an amendment to the CPCN to obtain a
water appropriation for the pipeline installations.
5.3
5.3.1
Mattawoman estimates that the average annual construction workforce
would be about 275 employees over an approximately three-year period.
In the peak construction period, up to 645 construction workers and other
personnel would be onsite. Mattawoman did not disclose payroll
estimates associated with construction employment, but prevailing wage
rates for construction occupations in Prince George’s County range from
approximately $20 to $30 per hour for skilled tradesmen and about $15
per hour for laborers (DLLR 2013), suggesting a considerable injection of
income into the State’s economy during construction.
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With an anticipated total construction cost of $475 million, expenditures
for facilities and equipment could exceed $285 million according to Jobs
and Economic Development Impacts (JEDI) Natural Gas Model
simulations (2012 dollars). Excluding expenditures on power generation
equipment and other plant equipment, which are likely to be outside of
the State, the JEDI model forecasts the Project to generate nearly $115
million in output among Maryland industries over the construction
period, and $74 million in indirect and another $45 million in induced
output through the multiplier effect. More than $2.1 million in sales tax
receipts would be collected on the direct sales of goods and equipment by
Maryland businesses.
Although some construction workers could conceivably commute from
out-of-state, there is an ample supply of construction labor in the
Baltimore and Washington metropolitan areas. In Prince George’s County
alone there were nearly 19,000 in construction and extraction occupations
in 2013, mostly in construction trades. Over 15,000 were in construction
and extraction occupations in Montgomery County and more than 9,000
in Anne Arundel County (DLLR 2013).
Post-construction, approximately 30 employees would operate the facility
with a payroll (including benefits) approaching $3.5 million annually.
Annual operations and maintenance (O&M) expenditures on goods and
services are expected to be $6.35 million.
While the numbers are significant in absolute terms, the economic impacts
from Project construction and operation are small relative to the Maryland
and Prince George’s County economies. Still, as a positive stimulus, both
the State and county would benefit economically from the Project.
5.3.2
Population and Housing
The proposed Project would not appreciably affect population or the
demand for housing in Prince George’s County because no permanent
construction worker immigration is expected. In addition to a sizable
construction labor force within Prince George’s County, the Site is within
commuting distance to a major construction labor pool within the
Baltimore and Washington metropolitan areas and is connected via two
major highways, MD 5 and US 301. The construction labor force is
therefore expected to commute to the Site on a daily basis rather than
relocate or reside in short-term transient accommodations. The addition
of 30 O&M employees would have no effect upon population and housing
conditions in the post-construction period.
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5.3.3
Land Use
The Mattawoman Site is located within the Developing Tier of Prince
George’s County on a parcel previously cleared and graded for a recycling
center. The Site is bounded by Brandywine Road (MD 381) to the north,
the CSXT Herbert Secondary rail line to the east, the Globecom Receiver
Site to the south, and an automotive salvage yard to the west. There is a
single residence adjacent to the Site situated opposite the property’s
entrance on Brandywine Road. Other adjacent properties are commercial
or institutional. The closest residential settlements are scattered along
Tower Road, Cherry Tree Crossing Road, and Brandywine Road east of
Tower Road, more than a quarter mile from the centroid of the Site.
Permanent land use impacts associated with construction and operation of
the Project are expected to be confined to the interior of the 88-acre parcel.
Approximately 28 acres would host permanent facilities. Additional land
would be occupied during construction for laydown, parking, and project
management. Land use impacts would result from site preparation,
foundation installation, and the erection of structures. PPRP has
recommended a licensing condition requiring Mattawoman to design the
facility in substantial conformity with the Site Plan drawings reviewed by
the Prince George’s County Planning Department.
Part of the Mattawoman Energy Center property is within the Joint Base
Andrews Outer Horizontal Surface zone (Zone F), with the rest within the
Approach-Departure Clearance Surface (Zone C). The Outer Horizontal
Surface is defined as an imaginary surface located 500 feet above the
established airfield elevation, and extends outward from the outer
periphery of the conical surface (Zone E) for a horizontal distance of
30,000 feet. The Approach-Departure Clearance Surface is symmetrically
centered on the extended runway centerline, beginning as an inclined
plane (glide angle) 200 feet beyond each end of the primary surface, and
extending for 50,000 feet. The slope of the Approach-Departure Clearance
Surface is 50:1 until it reaches an elevation of 500 feet above the
established airfield elevation. It then continues horizontally at this
elevation to its termination (AICUZ 2007).
Prince George’s County ILUC regulations forbid the issuance of building
permits for any structure exceeding the height of any imaginary surface.
As the tallest structures (two combustion turbine stacks and the auxiliary
boiler stack) of the Project are 100 feet above ground level (AGL), the
Project appears to be compatible with the county’s ILUC regulations.
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Figure 5-9
Height, Accident Potential, and Noise Intensity Zones
South of Joint Base Andrews
A potential land use conflict exists between Mattawoman and the United
States Air Force (USAF). The Project Site is directly north of the Globecom
Receiver Site, one part of the Andrews Tri-Link which also includes Joint
Base Andrews and the Davidsonville Transmitter Site (Figure 5-10).
Because of the Project’s location, the USAF is concerned with microwave
and high frequency communications interference, radio frequency
interference, and potentially other conflicts that could impact missions
affecting national security. The USAF is a party to this proceeding and is
independently reviewing the Project for potential impacts.
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Figure 5-10
Andrews Tri-Link Facilities
According to the applicant, Mattawoman’s reclaimed water pipeline
would be buried under existing road ROWs for most of its length. No
above-ground facilities would be constructed. Land use along the
proposed route from the Piscataway WWTP to MD 5 is predominantly
undeveloped although interspersed with low density residential and
agricultural properties. The pipeline bypasses a golf course on MD 373
(Accokeek Road) near its intersection with Berry Road, and the Lakeview
at Brandywine planned community near MD 5. West of MD 5, land uses
along the route are primarily commercial, industrial, and institutional.
The pipeline is not within the Chesapeake Bay Critical Area (CBCA) nor
does it bypass any lands under preservation easement.
Pipeline alignments outside State and county road ROWs were not
identified, but would be necessitated by insufficient room for occupancy
beneath the roadbed. Where the pipeline is outside the ROW, land use
impacts from trenching and installation would be temporary. Postconstruction, land would be restored to its previous state. Development
within the ROW would be restricted to that consistent with underground
utilities. As noted by the applicant, development along much of the
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reclaimed water pipeline route is already restricted by the area’s Rural
Tier designation and zoning. The Project would have no effect upon the
revitalization of the Village of Brandywine as articulated in the
Brandywine Revitalization and Preservation Study. PPRP concludes that
construction and operation of the reclaimed water pipeline would have no
direct or indirect effect upon land use along its proposed route.
The Project’s underground natural gas pipeline would be constructed
mostly within a CSXT railroad ROW and a PEPCO transmission line
corridor. In Prince George’s County, the pipeline route would deviate
south of the CSXT ROW onto property owned by the Maryland–National
Capital Parking and Planning Commission (M-NCPPC) for approximately
one-quarter mile until intersecting the PEPCO transmission line, and for
an approximate 0.9 mile “Greenfield Segment” in Charles County from
the transmission line corridor to its interconnection with the Dominion
Interstate Gas transmission line. The M-NCPPC land in Prince George’s
County is unoccupied and zoned Open Space (O-S). Private land
traversed in Charles County comprises three parcels zoned Rural
Conservation (RC). The parcels are unoccupied and are not under
protective easement. The natural gas pipeline route crosses the Cedarville
State Forest within the PEPCO ROW but is not within the CBCA. Within
Charles County the pipeline route is within the Zekiah Watershed Rural
Legacy Area.
During construction, temporary land use impacts from trenching and
installation would be confined to a narrow corridor adjacent to the
pipeline route. Post-construction, land would be restored to its previous
state. Development within the ROW would be restricted to that consistent
with underground utilities. As most of the route is within dedicated
ROWs, no adverse effects are expected from construction or operation of
the pipeline. Where the pipeline traverses lands outside dedicated
railroad or utility ROWs, development activities incompatible with
underground pipeline operations are restricted by land use controls.
PPRP concludes that construction and operation of the natural gas
pipeline would have no direct or indirect effect upon land use along its
proposed route.
The Project’s generator lead line would mostly parallel the CSXT rail line
to a PEPCO 230-kV transmission corridor that connects to the Burches Hill
substation. Near the Project Site the generator lead line would briefly
follow Brandywine Road, then turn north through an industrial property
before intersecting a SMECO sub-transmission line corridor. Lands
traversed or bypassed by the transmission line are zoned Light Industrial
(I-1), Rural Residential (R-R) and Open Space (O-S). Easements would be
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required from nine owners of properties to the east of the SMECO
easement.
The northernmost of these properties is protected under a Maryland
Agricultural Land Preservation Foundation (MALPF) easement. The
property is owned by Cheltenham Property, LLC, which entered into a
Deed of Easement (File No. 16-06-03) with the Maryland Department of
Agriculture on January 30, 2008. Restrictions that apply to easement
properties are generally governed by statutory and regulatory language in
the Public Laws of Maryland and COMAR, although the Deed of
Easement is the source for specific provisions that apply to a particular
property. COMAR 15.15.01.17(F)(1) states specifically “[a]fter a
landowner has sold an agricultural preservation easement to the
Foundation, the landowner may not grant or permit another to establish
an easement, right-of-way, or other servitude in that land without the
Foundation’s written permission.” The Cheltenham property’s Deed of
Easement contains a similar covenant in that “[n]o rights-of-way,
easements, oil, gas or mineral leases, or similar servitude may be
conveyed or permitted to be established on the land for any commercial,
industrial or residential use, without the Grantee’s express written
permission.”
Easement acquisition is enabled through a request for an Overlay
Easement, which may be granted by the Foundation’s Board of Trustees
upon recommendation by MALPF staff. Prior to this, the easement must
be approved by the Prince George’s County Council after receiving the
recommendation of the county’s Agricultural Preservation Advisory
Board. To date, Mattawoman has entered into an electric transmission
line easement agreement and an easement option agreement with
Cheltenham Property, LLC. The Maryland Department of Agriculture
(MDA) has indicated that MALPF will not consider granting an easement
to Mattawoman unless the Project has condemnation authority (Turner
2015).
PPRP has recommended an initial licensing condition requiring
Mattawoman, prior to construction of the generator lead line, to certify to
PPRP and the PSC that it has obtained approval for an Overlay Easement
from the MALPF Board of Trustees.
Originally sited on preserved land, Mattawoman has relocated its
proposed substation to a property to the west of the CSXT rail line and
Cherry Tree Crossing Road, and south of the PEPCO 230-kV transmission
corridor. The property contains a single residential structure and abuts a
property to the south occupied by a church. Both properties are heavily
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wooded, although much of the substation property would be cleared. A
manufacturer of concrete forming systems is located on an adjacent parcel
on the east side of Cherry Tree Crossing Road.
The property chosen for the substation is zoned R-E (Residential-Estate).
Under Public Utility Uses and Structures in Subtitle 27-441 of the Prince
George’s County Zoning Ordinance, electric power facilities or equipment
are a permitted use in the R-E zone. Other public utility uses and
structures, including major transmission and distribution lines and
structures, are permitted in the R-E zone subject to the approval of a
Special Exception.
5.3.4
Transportation
During construction, Prince George’s County would see an increase in
traffic on roads leading to the construction site, particularly during the
peak construction period when approximately 645 construction workers
are onsite. Access to the Mattawoman construction site would be via an
existing commercial driveway off Brandywine Road (MD 381).
Brandywine Road is a two-lane undivided State highway serving
communities in the Rural Tier and other Southern Maryland counties. It
traverses the commercial and historic core of Brandywine near its
intersection with Crain Highway (US 301). US 301 is a major
transportation corridor in Southern Maryland and a primary north‐south
commuter route from fast‐growing suburban communities in Prince
George’s and Charles counties. Key intersections in the area are MD
381/Cherry Tree Crossing Road and MD 381/Missouri Avenue, both
unsignalized, and signalized intersections of MD 381 with US 301 and
with MD 5. While most currently provide an acceptable level of service
(LOS), the intersection of MD 381/MD 5 operates below acceptable
standards during the morning peak hour. Traffic congestion in
Brandywine is expected to increase as approved residential and mixed use
developments reach fruition. However, most are as yet unbuilt or are
only partially completed. As a result, with the exception of MD 381/MD
5, intersections originally projected to operate below the accepted LOS
(LOS “D”) are now expected to continue operating satisfactorily over the
next 5 years (STS 2015a).
During construction worker shift changes, local traffic congestion is
expected at intersections near the Project Site, and traffic volumes could
cause periodic delays until distance from the Project Site distributes traffic
throughout the surrounding highway network. Since the projected
operational workforce is much smaller, post-construction traffic impacts
would be insignificant.
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To quantify traffic impacts, Mattawoman commissioned a traffic impact
study (TIS) (STS 2015a). Analysis of the four key intersections plus the
intersection of MD 381 and the site access driveway revealed that the MD
381/Missouri Avenue, MD 381/Cherry Tree Crossing Road, and MD
381/Site Access intersections would operate at acceptable levels of service
(LOS) after the facility is operational. The MD 381/MD 5 intersection
would continue to operate at an unacceptable LOS, although due to
background traffic growth rather than O&M employment at the
Mattawoman Energy Center.
During the peak construction period, however, the intersections of MD
381 with Missouri Avenue and with the site access driveway would also
operate at an unacceptable LOS during the evening peak hour, in addition
to operational issues at the two signalized intersections. Mattawoman’s
consultant suggested the MD 381/Missouri Avenue intersection could
benefit from a change in traffic control to address southbound traffic
delays during the evening peak period although, because background
traffic projections are conservative, the intersection should be monitored
along with area traffic growth during the early stages of construction to
determine if conversion from a stop-controlled to signalized intersection
for a temporary period of time is warranted (STS 2015a).
Mattawoman’s consultant also proposed shifting construction arrival and
departure times to before or after background peak hour traffic to address
traffic congestion during construction, and either a temporary traffic
signal or law enforcement management of the intersection of MD 381 and
the site access driveway during the peak construction period. The
consultant also suggested moving a planned guard house at the entrance
to control access to the Site further into the Site to prevent potential
queueing onto MD 381.
The Maryland SHA’s review of an earlier draft of the TIS (STS 2013)
generally concurred with the findings of the TIS that the Project would
have a negligible long-term impact to traffic operations within the study
area, but also concluded that impacts to nearby intersections during
construction would be substantial. Because the TIS did not include one,
SHA requested submission of a plan of mitigating actions for review prior
to construction. At minimum, the SHA recommended construction of a
westbound MD 381 exclusive left turn lane and an acceleration/
deceleration lane area along eastbound MD 381 at the site access
driveway. All improvements must be completed prior to the Site
generating substantial traffic demand and meet American Association of
State Highway Transportation Officials (AASHTO) and SHA policies,
design criteria, standards and practices for pedestrian and bicycle
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mobility. An access permit will be required for all construction work
within the SHA ROW. The SHA also provided several comments
requiring a point-by-point response and revisions to the TIS.
Mattawoman subsequently revised its TIS (STS 2015a) and complied with
SHA’s request for point-by-point responses and a Transportation
Management Plan (TMP) (STS 2015b, STS 2015c), all of which are
contained in its January 2015 Supplemental Filing. Based on the
information provided, the SHA concluded that the comments included in
its December 17, 2014 review letter were adequately addressed, and that
the proposed TMP was acceptable subject to refinement during
implementation. PPRP concurs with these findings and has included a
recommended licensing condition that addresses the SHA’s comments.
Portions of the study area contain three projects in Maryland’s
Consolidated Transportation Program (CTP). Planning for the US 301
South Corridor Transportation Study is currently on hold although
protective ROW funding has been allocated to preserve the viability of
alternatives under study. Construction and operation of the Mattawoman
Energy Center would not affect this project. Engineering and ROW
acquisition for the MD 5, Branch Avenue project is underway, but
construction funds have not been allocated. As a result, the project is not
expected to be affected by construction and operations traffic generated by
the Mattawoman Energy Center. Planning for the MD 5 Corridor
Transportation Study is underway, but no funds have been allocated for
engineering, design, or construction. The Mattawoman Energy Center
Project is not expected to adversely affect this project. Other SHA projects
planned near the study area, such as the Waldorf Area Project, are in the
planning stage only.
With respect to specific roadways near the Project Site, Brandywine Road
is designated a rural collector facility within an 80-foot future ROW
(MNCPPC 2013). No structures on the Project Site would be within the
dedicated ROW.
Transport of oversize/overweight equipment to the Project Site could also
affect traffic during construction. Approximately 40 heavy load deliveries
of equipment, such as the new CTs, steam turbine, electric generators,
HRSGs and transformers are expected. In its January 2015 Supplemental
Filing, Mattawoman has stated that, where possible, site deliveries would
be scheduled to occur outside of peak traffic hours (STS 2015b). PPRP
expects that trucks will traverse State highways to the Project Site. There
are no structures on the State of Maryland Highway System in Prince
George’s County that cannot carry legal weight vehicles. However,
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bridges on two Maryland highways in the county have vertical clearances
of less than 14.5 feet (SHA 2014).
To the extent that any loads of materials or equipment are oversize or
overweight, the Maryland SHA requires hauling permits for any loads of
materials or equipment that are “oversize vehicles” or “overweight
vehicles”, as defined by Title 24, Subtitle 1 of the Transportation Article of
the Annotated Code of Maryland. Prince George’s County also requires
permits for transporting extremely large and/or heavy items on public
roadways. The Prince George’s County Department of Permitting,
Inspection and Enforcement requires sufficient advance notice to conduct
an inspection of the proposed hauling route and for analysis of the
equipment. No bridges or certain culverts may be crossed if the combined
load is in excess of Maryland legal load or posted limits. Permits for
overweight/oversize vehicles issued by the SHA are valid for county
roads provided weight restrictions for structures are observed.
Mattawoman to comply with all permit requirements for transport of
oversize or overweight loads on State highways and Prince George’s
County roads, and to obtain appropriate approvals, as necessary.
Federal Regulation Title 14 Part 77 establishes standards and notification
requirements for objects affecting navigable airspace, including
determining the potential hazardous effect of the proposed construction
on air navigation. Notice must be filed with the Federal Aviation
Administration (FAA) if any construction is more than 200 feet high, or
exceeds an imaginary surface with any of the following: a slope of 100 to 1
up to a distance of 20,000 feet from the nearest point of a public use or
military runway of more than 3,200 feet in length; a slope of 50 to 1 up to a
distance of 10,000 feet from a runway of 3,200 feet or less; or with a slope
of 25 to 1 for a distance of 5,000 feet from a heliport. Maryland Aviation
Administration (MAA) notification requirements, which use the same
standard, are codified in COMAR 11.03.05.05.
The closest airport to the Project is Washington Executive Airport (W32), a
public use airport, more than 6 miles from the Mattawoman Site. From
the end of the nearest runway, Joint Base Andrews is approximately 7.5
miles to the north. The closest heliport is located at the Southern
Maryland Hospital Center in Clinton, about 4 miles away. Aircrews from
Joint Base Andrews use four landing zones at the nearby Globecom
Receiver Site to practice unimproved landing area operations. An
unimproved landing area is defined as no runway, and the facility is not
classified as a heliport. Helicopter flight patterns overfly the Project Site,
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however. In January 2014, the FAA issued a Determination of No Hazard
to Air Navigation for the exhaust stacks at the Project Site. The Project is
in compliance with FAA and MAA obstruction standards.
The reclaimed water pipeline would mostly occupy the ROWs of two
Prince George’s County roads, Farmington Road and Berry Road, and two
State roads, Accokeek Road (MD 373) and Brandywine Road (MD 381),
between the Piscataway WWTP and Project Site. The pipeline would also
cross under a county road (Livingston Road), two State highways (Old
Indian Head Highway (MD 210) and Branch Avenue (MD 5)), a federal
highway under State jurisdiction (US 301) and the CSXT Pope’s Creek
Secondary railroad line. The natural gas pipeline would be mostly within
transmission line and railroad ROWs, but would cross three county roads
in Charles County and two in Prince George’s. The generator lead line
would be within or adjacent to public roads and rail corridors for most of
its length, paralleling MD 381 for approximately one-tenth of a mile before
turning north and aerially crossing the State highway. The line would
also cross three county roads – Air Force Road, Old Indian Head Road,
and Cherry Tree Crossing Road – and would traverse the CSXT rail
corridor at three locations. The Mattawoman Energy Center Project
would connect to public water and sewer lines under Brandywine Road
near the entrance to the Site.
Construction of the pipelines would involve trenching to the maximum
extent possible and directional drilling under major roads, rail lines or
sensitive resources traversed by the facility. Trenching within the ROW of
roadways could affect traffic flows where construction is staged, although
construction is expected to be sequenced to minimize disruptions. In
addition, access to private driveways and businesses along the reclaimed
water pipeline route could be temporarily disrupted by excavation
activities. Post-construction, ROWs would be restored to their previous
conditions, with no long term impacts anticipated except for occasional
maintenance and repair activities.
Occupancy of State highway ROWs is subject to SHA’s utility policy (SHA
1998). In addition, an access permit would be required for all construction
within the SHA right-of-way (ROW). Prince George’s County policy on
utility accommodation is detailed in its Policy and Specification for Utility
Installation and Maintenance (DPW&T 2007). Work within a Charles
County ROW is addressed in the county’s Road Ordinance (DPGM, 2011).
Utility encroachment or temporary access to CSXT property is subject to
the railroad’s permitting process (CSX 2012).
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PPRP has recommended a licensing condition requiring Mattawoman to
obtain appropriate utility permits from the Prince George’s County
Department of Public Works, Charles County, and the Maryland State
Highway Administration to construct the reclaimed water and natural gas
pipelines, and the generator lead line. For pipeline construction within
SHA ROWs, PPRP has recommended an initial licensing condition
requiring Mattawoman to submit to the SHA a Maintenance of Traffic
(MOT) plan that details work zone impact management strategies on State
highways that will be affected by the Project. The MOT plan must be
approved by the SHA prior to the issuance of an access permit for
construction within the right-of-way.
5.3.5
Visual Quality
The Mattawoman Energy Center Site is situated on a parcel previously
cleared and graded for a recycling center. The Site exhibits little in the
way of terrain relief. Views from Brandywine Road are unencumbered by
vegetation or other buffers, although public views of the Site from other
directions are limited. Visual quality in the area is compromised by
electric distribution lines along roadsides, communications towers, a
railroad line along the property’s eastern boundary, and nearby
commercial and institutional buildings. The character of Brandywine
Road near the Site has been described as “very utilitarian, with limited
aesthetic appeal” (MNCPPC 2011).
The proposed Project would be situated to the east of the CSXT rail line,
which forms the eastern property boundary to the Site, offset from
Brandywine Road by more than 1,500 feet. At 100 feet AGL, two
combustion turbine stacks and an auxiliary boiler stack would be the
tallest structures of the power plant. Other structures would be less than
80 feet high although the vapor plume from cooling towers could extend
the Project’s vertical profile.
Visibility of existing tall structures in the vicinity of the Project,
particularly the adjacent 113 foot USAF Doppler radar tower suggests the
Project would have a minimal visual impact upon the surrounding area.
Views from residences along Cherry Tree Crossing Road and Tower Road
are screened by street-side vegetation, primarily mature trees, which are
effective buffers even when foliage is seasonally reduced. The same can
be said for residences along Brandywine Road east of the Project. Except
for a single residence opposite the site access driveway, unencumbered or
partial views are from commercial or institutional establishments and
from motor vehicles passing the Site on Brandywine Road.
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Brandywine Road, from the Pope’s Creek Secondary CSXT rail line to
North Keys Road is a designated historic road. The county’s Master Plan
of Transportation notes that natural and cultural resources adjacent to
scenic and historic roads are in need of protection, and scenic easements
have been established along some scenic and historic roads in the county
(MNCPPC 2009d). New development proposals are typically conditioned
on the placement of development out of the viewsheds of designated
scenic and historic roads or through the establishment of scenic easements
(buffers) along a property’s frontage. Buffering requirements for county
designated historic roads in the Developing Tier are defined in the Prince
George’s County Landscape Manual (MNCPPC 2010c) which requires a
minimum 20 foot buffer to be planted with a minimum of 80 plant units
per 100 linear feet of frontage, excluding driveway openings.
PPRP agrees with Mattawoman that the Project is expected to have only a
minor visual impact on the general area. PPRP recommends a licensing
condition requiring Mattawoman to establish a buffer along Brandywine
Road to provide screening for nearby residential lots and motorists.
Enhancements should be in substantial conformance with buffering
requirements defined in Section 4.6(c)(2)(A)(ii) of the Prince George’s
County Landscape Manual.
Outdoor lighting for the Project could adversely affect nearby properties
through light trespass, or could add luminance (skyglow) to the night sky.
Outdoor lighting is required on all new and modified project components
to satisfy operational, Occupational Safety and Health Administration
(OSHA), Federal Aviation Administration (FAA), and security
requirements. Joint Base Andrews has also expressed concern about glare
affecting its operational needs. Although Mattawoman did not address
facility lighting in its application, light trespass onto nearby properties is
expected to be mitigated by the facility’s location within the Project
property and the landscape buffer along Brandywine Road. Skyglow
should be minimized through the selection of appropriate luminaries and
supporting structures. PPRP has recommended a licensing condition
requiring Mattawoman to develop a lighting distribution plan to mitigate
intrusive night lighting and avoid undue glare onto adjoining properties.
Mattawoman must submit the plan to PPRP, Joint Base Andrews, and the
PSC for review and approval prior to operation of the Project.
Construction of linear facilities for the Project would require excavation
and installation activities along the proposed routes. While much of the
natural gas pipeline route is within corridors that are only partly
accessible to the public and where views contain transmission line
structures and conductors and/or railroad infrastructure, the reclaimed
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water pipeline follows public roads. Construction activities and
associated work zone infrastructure for traffic safety and control are likely
to be highly visible to passing motorists and property occupants along the
route. However, visual impacts would be transient and temporary.
Except when undergoing maintenance or repair, Mattawoman’s natural
gas and reclaimed water pipeline would have no visual impact in the
post-construction period.
Mattawoman’s generator lead line would comprise 19 tubular steel poles
supporting three sets of conductors over spans ranging from 700 to 900
feet. The poles would be 140 feet high and range in diameter from 4 to 8
feet. The transmission line would span a mix of land uses, but would be
primarily within or adjacent to utility (including rail) corridors. The
proposed substation would consume approximately 5.3 acres of the 7.3acre site.
From the Herbert Secondary CSXT rail spur to the proposed substation,
public views of the generator lead line would be limited to motor vehicle
traffic on Cherry Tree Crossing Road, and occupants of residential
properties and employees of businesses with frontage onto Cherry Tree
Crossing Road. Otherwise, the views of the corridor are buffered by
mature woodlands, particularly to the east but also from the west where
the residential community of Cheltenham approaches the corridor. The
southern segment of the generator lead line, which parallels MD 381
before turning north through an industrial property would be visible to
motor vehicle traffic on Brandywine Road, to a residence opposite the
entrance to the Project Site, and nearby businesses.
Views along the entire length of the proposed generator lead line route are
currently encumbered by periodic railroad operations, multiple
transmission lines within or adjacent to the CSXT corridor, electric
distribution lines along MD 381, communications facilities, and nearby
commercial and institutional buildings. While the transmission line
would introduce additional utility structures to views within its proposed
corridor, PPRP has concluded that visual impacts would be spatially
confined due to existing vegetation and views only marginally more
impaired than currently experienced.
If, as stated by the Applicant, the proposed substation is buffered to the
west and south by existing trees, public views of the facility would be
mostly confined to motorists from a short segment of Cherry Tree
Crossing Road where the road and property adjoin. Neither a
neighboring lot occupied by a church nor a nearby industrial property
would be visually affected by the substation. Prince George’s Master Plan
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of Transportation does not list Cherry Tree Crossing Road as an historic or
scenic road. The substation would be subject to standards set forth in the
county’s Landscape Manual (MNCPPC 2010c). In Prince George’s
County, a landscape plan is a required element of all detailed site plans.
As noted earlier, PPRP has recommended an initial licensing condition
requiring Mattawoman to design the facility in substantial conformity
with Site Plan drawings reviewed by the Prince George’s County Planning
Department.
5.3.6
Fiscal
During construction, revenues from taxes on construction worker wages,
income taxes on indirect and induced employment incomes, and sales
taxes on consumption expenditures would accrue to Maryland and local
governments. Depending on where construction labor resides and where
materials and supplies are procured, nearby states would reap fiscal
benefits as well. As most of the construction labor force is expected to be
drawn from workers living in the Washington and Baltimore metropolitan
areas, the Project would generate most income tax revenues in these
jurisdictions. Mattawoman estimated that personal state income tax
revenues from construction worker wages could be approximately $2.375
million. Income tax revenues to Prince George’s County could exceed
$600 thousand over the construction period (MNCPPC 2013).
Fiscal post-construction benefits would include personal income tax
revenues to the State and Prince George’s County from direct, indirect and
induced employment gains, and corporate income tax revenues from the
operating company. Depending upon the proportion procured from
Maryland industries, Mattawoman estimates state sales tax revenues from
the purchases of goods and services could increase by $381 thousand
annually.
Prince George’s County estimates that direct and indirect postconstruction employment would generate more than $44 thousand in
income tax revenues annually. However, the most significant revenue
impact to Prince George’s County would be from property taxes.
Mattawoman estimates that real and personal property taxes would
average approximately $3 million over the first 20 years of Project
operation. Currently, the Mattawoman property generates roughly
$27,500 per year in taxes (MNCPPC 2013). Additional property tax
revenues would accrue from the generator lead line and substation.
Construction could marginally affect public services in Prince George’s
County. For example, the Project could increase demands upon State and
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county emergency services, such as fire, rescue, and police services,
particularly when construction traffic is added to other commuting traffic.
Injuries from accidents at the construction site could place additional
demands on rescue and medical services. These impacts can be mitigated
by good construction management and safety awareness practices and by
scheduling shift changes to reduce construction traffic congestion.
Because most construction workers are expected to commute to the Site,
the Project should have no adverse effect upon school enrollment or place
any additional demands upon public services that are sensitive to
population.
Prince George’s County’s fire, rescue, and emergency medical service
(EMS) would be available through the 911 dispatch center to provide
additional resources as necessary. Emergency services in response to
offsite incidents would be dispatched through 911, as well. 911
emergency dispatching is from Public Safety Communications Center, one
of the agencies within the Prince George’s County Office of Homeland
Security. The county’s Fire and Emergency Medical Services Department
has two units that respond to mass casualties. The county maintains
standard response plans for all major incidents.
The Project is within the first response area of the Brandywine Volunteer
Fire Department (Station 40), located next door to the Site. The company
is staffed by both career and volunteer personnel and houses a paramedic
unit that provides Advanced Life Support (ALS). Because the
Brandywine Volunteer Fire Department is a combined career/volunteer
system, an accident at the Mattawoman Site during construction or
operation could temporarily strain local resources. As a result, PPRP has
recommended a licensing condition requiring Mattawoman, prior to
construction, to contact the Prince George’s County Fire and Emergency
Medical Services Department and the Brandywine Volunteer Fire
Department to address Site safety and EMS coverage, establish timely
response options and facilitate emergency vehicle access throughout the
Site in case of an accident or injury. Where existing emergency response
capabilities are determined to be inadequate, Mattawoman should assist
these organizations through contributions, training and/or general
support.
Post-construction, the projected permanent workforce is not expected to
have an adverse effect upon public services in the county.
In summary, given a significant post-construction tax revenue stream and
minimal project-related outlays from county budgets for public services
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during construction and operation, the net fiscal impact of the Project on
Prince George’s County is expected to be favorable.
5.4
CULTURAL IMPACTS
Construction of the Project would include clearing and grading for both
permanent and temporary facilities, installation of pilings and
underground utilities, foundation construction, and erection of equipment
and buildings. Most potential effects on cultural resources would be
within the Project property, although some visual and noise impacts could
extend beyond the Project boundaries to nearby cultural resources. Postconstruction impacts on cultural resources would be confined to the
Project property.
The Mattawoman property has not been the subject of previous
archeological, architectural, or historical investigations. However, the
majority of the Project Site has been extensively cleared and graded, and a
Phase I archeological survey was not recommended. Evidence of
previous occupancy of the Site no longer exists, and no documented
historical or archeological resources are associated with the Project Site.
The MHT concurs that the Project would have no effect upon historic
properties.
The Southern Maryland Railroad, recorded as an archeological site
(18PR606) which extends into Charles County, is adjacent to the property.
Constructed in the 1870s, the railroad operated until 1965. The Prince
George’s County portion of the railroad has not been assessed for
National Register eligibility. The Project would not affect the property’s
cultural resource value.
According to the applicant, the Project would not be visible from historic
sites located in the village of Brandywine and would thus not have an
adverse effect on these properties (MNCPPC 2013).
For the most part, Mattawoman’s reclaimed water and natural gas
pipelines would be constructed within existing ROWs that have been
previously disturbed. The reclaimed water pipeline route bypasses a
National Register property in Brandywine, the Early Family Historic
District, and several properties on the Maryland Inventory of Historic
Properties (MIHP). The Historic Preservation Section of the Prince
George’s County Planning Department has noted that several historic
resources located along the route of the proposed reclaimed water line are
located on Accokeek Road, some of which are very close to the ROW, and
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must be avoided during construction. The natural gas pipeline traverses
the Cedarville State Forest and interconnects with the Dominion Cove
Point transmission line near the Sparks-Mudd Log House, a ruin listed in
the MIHP that was previously determined to be not National Register
eligible. The Dr. Samuel A. Mudd House, a National Register property, is
about a mile from the pipeline interconnect. The generator lead line
traverses an industrial property in Brandywine and otherwise is within or
adjacent to transportation and utility corridors.
In August 2014, MHT reviewed the proposed linear facilities corridors as
they were then proposed and determined that the Project would have no
adverse effect upon historic properties (Henry 2014). However, MHT’s
review was prior to proposed changes to the pipeline route. MHT
subsequently recommended that Phase I archeological survey work
would be needed for the 0.9-mile section of the proposed natural gas
pipeline alignment that exits the PEPCO corridor north of the Jordan
Swamp (“Greenfield Segment”). Mattawoman submitted a cultural
resources report for the Greenfield Segment in its January 2015
Supplemental Filing, which concluded that no historic properties would
be affected (SEARCH 2015a). Following its review, MHT concurred that
the affected area possesses no archeological research potential and that
further archeological investigations are not warranted (Henry 2015). In
addition, after reviewing the archeological and historic aspects of the
generator lead line route, the MHT concluded that no cultural resource
investigations are warranted for this element of the Project (Henry 2015).
After relocating the proposed substation for the generator lead line,
Mattawoman conducted a cultural resources investigation over the 7.3acre parcel. A cultural resources report was subsequently submitted in
Supplemental Testimony on April 16, 2015 concluding no historic
properties would be affected (SEARCH 2015b). Because MHT has not yet
issued a formal determination of effect on historic properties for the
revised substation location, PPRP has recommended an initial licensing
condition requiring Mattawoman, prior to construction, to consult with
the MHT to determine whether additional archeological investigations
will be required. If the MHT determines that the substation will have no
adverse effect upon historic properties, Mattawoman should submit
MHT’s formal determination to the PSC and PPRP. Otherwise, to the
extent that subsequent archeological investigations determine that cultural
resources would be adversely affected by the Project, the resolution of all
adverse effects will require the negotiation and execution of a
Memorandum of Agreement (MOA) between the MHT, Mattawoman,
and other involved parties stipulating the agreed-upon mitigation
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measures that will be implemented by Mattawoman prior to construction.
This consultation process shall include Prince George’s County.
Both the reclaimed water pipeline (at Branch Avenue) and natural gas
pipeline (at Poplar Hill Road) would intersect Booth’s Escape Scenic
Byway, part of the SHA’s Scenic Byway Program. The byway follows the
route John Wilkes Booth used to escape from Washington after
assassinating President Lincoln at Ford’s Theater in 1865. Recognized for
its historical associations and located primarily within major
transportation corridors, the scenic byway would not be adversely
affected by the Project.
The natural gas pipeline would be partly within the boundaries of the
Southern Maryland Heritage Area (SMHA). The SMHA consists of eleven
distinct clusters containing a concentration of heritage resources, existing
or proposed interpretive facilities, and significant lands protected by
federal, State and County ownership or easements. These clusters are
connected by corridors such as scenic byways, trails, and waterways. The
plan identifies key themes to guide visitors through Southern Maryland’s
history and identity and stresses stewardship principles for sustaining
and enhancing the region’s heritage tourism initiative. The pipeline
would traverse a part of Cluster #2 where it is within the Cedarville State
Forest. As the pipeline would be buried within an existing transmission
line corridor, PPRP has concluded that the Project would have no adverse
effect upon heritage resources associated with the SMHA.
In the event that relics of unforeseen archeological sites are revealed and
identified during construction of the power plant or associated linear
facilities, PPRP has recommended a licensing condition requiring
Mattawoman to consult with the MHT to develop and implement a plan
for avoidance and protection, data recovery, or destruction without
recovery of such relics or sites, subject to MHT’s written approval.
5.5
NOISE IMPACTS
PPRP has utilized information provided by Mattawoman to evaluate noise
levels at nearby receptors that could result from operation of the proposed
facility. The objective of the analysis was two-fold: (1) to verify the
predicted noise levels that Mattawoman had presented in Table 5.5-1 of
the environmental report submitted with the CPCN Application, and (2)
to determine what licensing conditions should be recommended to the
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PSC to ensure that the proposed facility operates in compliance with
applicable State regulations.
5.5.1
Summary of Regulatory Requirements
Maryland State noise regulations specify maximum allowable noise levels,
shown in Table 5-5 (COMAR 26.02.03). The maximum allowable noise
levels specified in the regulations vary with zoning designation and time
of day. The noise limit for residential areas is 55 dBA (A-weighted decibel
scale) during nighttime hours and 65 dBA during daytime hours.
Table 5-5
Maximum Allowable Noise Levels (dBA) for Receiving Land
Use Categories
Zoning Designation
Industrial
Commercial
Residential
Day
75
67
65
Night
75
62
55
Source: COMAR 26.02.03
Note: Day refers to the hours between 7 AM and 10 PM; night refers to the hours between 10 PM and 7
AM.
The State regulations provide certain exemptions for specified noise
sources and noise generating activities. For example, motor vehicles on
public roads are exempt from Maryland noise regulations; however, while
on industrial property, trucks are considered part of the industrial source
and are regulated as such. The regulations also allow for construction
activity to generate noise levels up to 90 dBA during daytime hours, but
the nighttime standard may not be exceeded during construction.
While the State has adopted target levels for noise, enforcement authority
for noise regulations rests with local government (in this case, Prince
George’s County).
5.5.2
Estimate of Noise Impacts
Using the source noise information provided by the applicant, PPRP
prepared screening-level estimates of the sound pressure levels that
would result at various receptors surrounding the Mattawoman Energy
Center Site when the proposed facility is operating at full load.
Components included in the noise assessment include the combustion
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turbines, boiler, steam turbine generator, and cooling tower. Sound
pressure levels at varying distances were calculated using the following
formula (EEI Volume I, 2nd Edition, 1984):
Lp = Lw + DI - 20 log(r) - Ae - 11
where:
Lp is the sound pressure level
Lw is the source sound power level in dB
DI is a source directivity factor (we assumed hemispherical
spreading, DI = 3)
r is the distance from the source to the receptor location in meters
Ae is the excess attenuation caused by atmospheric absorption and
anomalous absorption
PPRP’s noise impact calculations are based on the distance to each
receptor from the center of the power block, according to the proposed
facility layout. “Standard Day” conditions were used, defined as an
average temperature of 59°F and a relative humidity of 70 percent, to
account for atmospheric attenuation. Anomalous attenuation is caused by
sound interferences due to site conditions such as weather patterns, wind
turbulence, natural barriers, and vegetation. To be conservative, PPRP
selected the minimum anomalous absorption factors (EEI Volume I, 2nd
Edition, 1984).
PPRP selected four receptor locations to calculate the noise impacts of the
proposed Project. The receptor locations were selected to represent those
areas potentially experiencing the greatest noise impact. The four receptor
locations modeled in this analysis are the following (see locations in
Figure 5-11):
•
Receptor 1, located on Brandywine Road to the northeast of the
Site;
•
Receptor 2, located near the entrance gate to the Mattawoman
property, at the northwest portion of the Site;
•
Receptor 3, to the west of the Mattawoman Site between the rail
line and Air Force Road, adjacent to the nearest residential area in
that direction; and
•
Receptor 4, on the western boundary of the Mattawoman Site at the
border with the adjacent industrial property (automobile salvage
yard).
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The State’s residential noise limits of 65 dBA daytime and 55 dBA
nighttime would need to be met at Receptors 1, 2, and 3. At Receptor 4,
the industrial noise limit of 75 dBA (day and night) would apply.
Figure 5-11
Table 5-6
Predicted Sound Pressure Levels (dBA)
Receptor 1
Receptor 2
Receptor 3
Receptor 4
Proposed Facility
54.7
55.6
47.7
58.5
Existing Noise Levelsa
39
42
37
--
Predicted Noise
Levels
54.8
55.8
49.4
58.5
(a) L90 ambient sound pressure levels from Table 3-4 were used to account for the existing noise levels
at each residential receptor location (Receptors 1, 2, and 3).
Table 5-6 summarizes the results of PPRP’s calculations, taking into
account the baseline noise levels that Mattawoman measured in its
assessment of existing conditions. While the proposed facility will create
an increase in baseline noise compared to current levels, the predicted
noise levels do not represent a discernible exceedance of the State noise
limits. The predicted noise level at Receptor 2, 55.8 dBA, is slightly higher
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than the residential nighttime noise limit of 55 dBA; however, the human
ear is typically unable to detect a difference of less than 1 dB. In addition,
it should be noted that PPRP’s noise evaluation methodology is
conservative in that it does not account for any shielding or barrier effects,
which may further reduce noise propagation from the source to the
receptor location.
At Receptor 4, on the boundary with an industrially zoned property, noise
from the proposed Project will not exceed the applicable noise limit of 75
dBA.
The adjacent properties closest to the power block, to the east and south of
the Mattawoman Site, are currently zoned as open space and are
undeveloped. This zoning allows for low-intensity residential use (5-acre
lots), and is intended to promote the economic use and conservation of
land for agriculture, natural resource use, large-lot residential estates, and
non-intensive recreational use. It is likely that operation of the proposed
Project would create noise levels at the eastern and southern property
boundaries that would exceed the target level for residential noise
impacts. While this would not constitute regulatory non-compliance as
long as the land remains undeveloped, the presence of the proposed
power plant may limit future uses of the adjoining parcels.
After the facility begins operation, Mattawoman should conduct postconstruction noise monitoring to verify that the facility is operating in
compliance with applicable noise regulations. PPRP’s recommended
licensing conditions are included in Appendix A.
5.6
ANALYSIS OF OTHER ENGINEERING IMPACTS
5.6.1
Water Supply
The proposed combined cycle facility will need water primarily for the
cooling towers, HRSG makeup, evaporative cooler makeup, and periodic
equipment washes. Mattawoman has identified reclaimed water from the
Washington Suburban Sanitary Commission’s (WSSC) Piscataway
Wastewater Treatment Plant (WWTP) as its preferred water supply
source.
Mattawoman estimates that the total average daily water use for plant
needs (other than potable water) will be 4.95 million gallons per day
(mgd). Water needs will vary from 3.6 mgd to 6.3 mgd depending on
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ambient conditions. More than 98 percent of the total water intake will be
lost to evaporation in the cooling towers.
The Project will employ a zero liquid discharge system, generating no
continuous process wastewater. The water balance diagrams in Figures 512 and 5-13 detail the summer maximum and winter maximum
(respectively) water usage rates for the proposed Project, based on
Mattawoman’s initial conceptual design.
Potable water for domestic uses (i.e., drinking water, sinks, toilets, etc.)
will be provided to the Project Site via an extension from the WSSC’s
municipal water supply system. Mattawoman estimates that 1,250 gallons
per day will be needed from the potable water system for domestic uses.
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Figure 5-12
Water Balance – Summer Maximum
Source: Mattawoman Response to PPRP Data Request No. 17-1, April 2015.
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Figure 5-13
Water Balance – Winter Maximum
Source: Mattawoman Response to PPRP Data Request No. 17-1, April 2015.
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5.6.1.1
Reclaimed Water Source
PPRP has established, in previous licensing cases, that reuse of treated,
reclaimed water for power plant cooling is beneficial because this option
avoids impacts to aquatic biota associated with the withdrawal of water
from surface water, and it conserves high quality water resources for other
users. Mattawoman has reached agreement with the WSSC to purchase
reclaimed water from the Piscataway WWTP. The Piscataway plant is
projected to have a sufficient amount of treated effluent to supply all the
reclaimed water needed for the Project. The WWTP has a permitted
capacity of 30 mgd based on the NPDES Permit effective May 2010; the
average discharge volume is approximately 21 mgd (MDE, 2013).
Compared to the maximum water needs of 6.3 mgd, Piscataway WWTP’s
discharge can provide an adequate quantity of water for the proposed
Mattawoman Project.
Mattawoman will construct a new 10-mile pipeline to convey reclaimed
water from the Piscataway WWTP to the proposed Project Site. At the
WWTP, Mattawoman will construct a lift station. Figure 5-14 shows the
location of Mattawoman’s proposed facilities within the layout of the
Piscataway WWTP site.
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Figure 5-14
Proposed Lift Station at Piscataway WWTP
Source: Mattawoman Supplemental Direct Testimony of Steven Tessem, Exh. ST-5, filed 30 June 2014
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The Piscataway WWTP is a tertiary treatment facility, which means that it
incorporates physical, chemical, and biological treatment processes,
resulting in high-quality effluent. The WWTP recently completed an
enhanced nutrient removal (ENR) system upgrade. Disinfection is
achieved by ultraviolet radiation; chlorine is not currently used or stored
on site.
Mattawoman provided a copy of the Piscataway plant’s NPDES permit
and data from daily effluent measurements for January 2012 to April 2013,
in response to PPRP Data Request No. 3; the water quality data are
summarized in Table 5-7 below. The WWTP is not required to sample
and analyze for additional organic or inorganic constituents under its
NPDES permit conditions. As part of the detailed design of the power
plant cooling system, Mattawoman will have to conduct additional
characterization of the reclaimed water quality to determine the need for
treatment additives that support optimal water chemistry.
Table 5-7
Water Quality Parameters in Piscataway WWTP Effluent
Constituent (parts per million,
ppm, unless specified)
Piscataway
WWTP
Effluent Conc.
Range
Piscataway
WWTP
Effluent Conc.
Average
Drinking Water
Standards c
pH (pH units)
6.50 - 7.90
7.06
6.5 – 8.5
Turbidity (FTU)
0.57 - 6.58
1.0
-
Alkalinity
65 - 171
116
-
Total suspended solids
<1 - 32.6
0.68
-
<1 - >2419
32.4
5% Positive
14.6 - 2419.6
221
5% Positive
BOD (5-day)
<2 - 24.2
1.15
-
Nitrate + nitrite (as N)
ND - 5.16
1.66
11.0
Ammonia as N
ND - 5.12
0.107
-
Total Kjeldahl nitrogen
ND - 10.1
0.74
-
Total phosphorus
ND - 1.22
0.058
-
<0.04 - 0.57
0.04
-
General Water Quality
E. Coli
Total coliform (MPN/100mL)
Orthophosphate (weekly)
Note: 1 FTU = 1 NTU
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5.6.1.2
Previous Studies Regarding Use of Reclaimed Water for Cooling Water Supply
The use of reclaimed water for nonpotable water supply is becoming more
common in Maryland and across the country. In the southwestern United
States and Florida, where high quality surface water and ground water
supplies are either not abundant or inaccessible, beneficial reuse of treated
wastewater has a long history. Power plants and other industries in the
greater Los Angeles metropolitan area have been using WWTP effluent
for cooling since the late 1960s. In addition, reclaimed water has been
used for many years for irrigation in Maryland and other states,
particularly for golf courses and agricultural and horticultural
applications.
PPRP’s experience with treated effluent reuse encompasses the following
projects:
•
The Panda-Brandywine generating station in southern Prince George's
County utilizes reclaimed water from the Mattawoman WWTP. This
facility was licensed by the PSC in the summer of 1994 and has been
operational since 1996.
•
Use of the Mattawoman WWTP effluent was approved by the PSC for
the Kelson Ridge power plant in 2002 (applicant canceled plans for
that facility).
•
Use of treated effluent in Frederick County was approved by the PSC
for the Catoctin Power facility in 2005 (that facility also has not been
built).
•
The Brandon Shores coal-fired power plant has been utilizing treated
effluent from Cox Creek WWTP as makeup for its flue gas
desulfurization (FGD) system since 2010 (this project was subject to
PSC approval as part of the CPCN review process for the facility
modification).
During the licensing proceedings for the Panda-Brandywine facility, PPRP
performed an extensive evaluation of the suitability of using reclaimed
wastewater for cooling tower makeup water. PPRP’s analyses included
the suitability of reclaimed wastewater in terms of both quantity and
quality for use in process cooling, potential risks associated with cooling
tower drift including deposition on crops, and process controls that would
ensure there would be no adverse impacts to human health or the
environment while using reclaimed wastewater. The findings from
PPRP’s analyses are summarized below and are documented in detail in
the February 1997 PPRP report entitled Environmental Review of the PandaBrandywine Cogeneration Project.
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•
Tertiary treated WWTP effluent is of sufficiently high quality that it
can be used in a power plant’s cooling system.
•
WWTP effluent has been used in similar applications in other parts of
the country for approximately 30 years without operational or healthrelated incidents.
•
A quantitative assessment of human health risks associated with
emissions from the cooling tower based on inhalation and potential
residential exposures to soils affected by deposition concluded that the
use of the WWTP effluent proposed by Panda-Brandywine poses no
unacceptable human health risks. However, maintaining a measurable
free chlorine residual for disinfection purposes, along with routine
monitoring of other water quality parameters, was recommended to
ensure the water being used in Panda’s cooling tower is consistently
acceptable.
In 2012, the U.S. EPA published updated guidelines for use of reclaimed
water, including cooling systems at power plant facilities (EPA 2012). The
Piscataway WWTP treated effluent meets these guidelines, provided that
a detectable level of free chlorine is maintained to prevent biological
growth (see discussion below).
Effluent from tertiary treatment facilities is typically of high quality, and
the Piscataway WWTP effluent falls within this category. Sanitary
discharges from domestic use make up the great majority of the facility’s
incoming flow; the discharge is not expected to contain any organic or
inorganic pollutants of concern. It should be noted that in the previous
CPCN licensing review under PSC Case No. 8488, PPRP thoroughly
reviewed the use of Piscataway WWTP effluent as a potential source of
cooling water for the Panda-Brandywine combined cycle facility, and
concluded that the treated effluent quality from Piscataway was suitable
for power plant cooling.
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5.6.1.3
Operational Requirements
PPRP’s previous evaluations of reclaimed water as a water supply option
for power plants have concluded that reclaimed water is a viable option
for use in power plant cooling systems. From a human health standpoint,
it is critical to disinfect the treated effluent for a sufficient amount of time
to ensure that any pathogens that may remain in the effluent are
destroyed prior to use in the cooling water system, and to prohibit the regrowth of microorganisms in the conveyance and water storage systems
between the WWTP and the power plant. Adequate disinfection is
necessary to prevent any risk of airborne dispersal of disease-carrying
organisms. The critical location for demonstrating adequate disinfection
is at the point at which the reclaimed water is transferred into the cooling
water system to ensure that any pathogens present due to re-growth are
destroyed prior to release in the cooling tower drift.
Mattawoman states that under the terms of its purchase agreement,
Piscataway WWTP is required to deliver water that conforms with
Piscataway’s NPDES permit. PPRP’s recommended licensing conditions
would further require that the reclaimed water entering the lift station at
the Piscataway WWTP have acceptable turbidity levels (less than 5
nephelometric turbidity units, NTU) and a detectable level of free
chlorine. If either of these conditions is not met, the water should not be
allowed to enter the pipeline to the Project Site.
The applicant plans to construct a 5.5-million-gallon storage tank at the
Mattawoman site to provide a 24-hour supply of cooling water in case of
upset conditions at the Piscataway WWTP. Chlorine levels should be
continuously monitored at the inlet to this tank, and additional chlorine
dosing performed whenever the free chlorine level becomes nondetectable. Finally, Mattawoman should have the ability to dose the water
with additional chlorine, if necessary, to re-establish the free chlorine
residual at the point at which water enters the cooling system.
PPRP recommends that Mattawoman be required to submit design
documentation, prior to start of construction, to confirm that adequate
monitoring and treatment will be incorporated in the management of
reclaimed water, from the point at which Mattawoman accepts water at
the Piscataway WWTP to its ultimate use at the proposed power plant
cooling tower. Mattawoman should also be required to submit standard
operating procedures (SOPs), prior to the start of commercial operation,
describing the management of reclaimed water. The SOPs should
address, for example, the expected retention time for water in the on-site
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storage tank, and how the storage tank system will be operated during
and following periods of facility shut down. Mattawoman should be
required to obtain PSC and PPRP approval for these submittals. With
proper design and operation of the cooling water system, human health
risks from the use of reclaimed water will be negligible.
5.6.2
Fuels and Chemicals Delivery, Handling, and Storage
The Project CT/HRSG units will be designed and permitted to fire only
pipeline-quality natural gas. Mattawoman will install a natural gas fuel
system with filters, pressure control, metering, and heating system. The
Project includes a 20-inch pipeline to transport natural gas to the Site. The
natural gas pipeline will originate in Charles County, Maryland, at a tie-in
point within an existing 36-inch Dominion Cove Point interstate gas
pipeline located approximately 7.4 miles south of the Site.
Natural gas combusted at the Project will be typical pipeline-quality gas
with an annual average total sulfur content of 0.25 grain of sulfur per 100
standard cubic feet (gr S/100 scf) and a maximum (short-term) sulfur
content of 1.0 gr S/100 scf. Based on a natural gas HHV of 1,046 British
thermal units per cubic foot (Btu/ft3), both CT/HRSG units will combust
approximately 5.34 million standard cubic feet per hour operating at 100
percent load with CT inlet air evaporative cooling, HRSG duct burner
firing, and at International Organization for Standardization (ISO)
conditions of 59°F and 60 percent relative humidity.
Upon reaching the Site, the gas will first be sent through a flow-metering
station, a gas pressure control station, and knockout drum for removal of
liquid that may have been carried through from the pipeline. The natural
gas will then pass through a filter/separator to remove PM and entrained
liquids.
Mattawoman will use small quantities of ULSD for the emergency
generator and fire water pump diesel engines. This will be delivered to
and stored in day tanks near the engines. The ULSD fuel oil will have a
maximum sulfur content of 15 ppm by weight. Each generator or pump
will have its own dedicated fuel oil tank with secondary containment.
Federal and State regulations include requirements for storage of all
petroleum products, including diesel fuel. Federal regulations (40 CFR
112) require that a Spill Prevention, Control and Countermeasures (SPCC)
Plan be prepared and implemented for any facility that stores more than
1,320 gallons of oil above ground. The SPCC Plan must contain a
description of sound engineering principles to be employed by the facility
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to minimize the potential for oil spills as well as appropriate response
measures to be taken in the event of a spill. The SPCC Plan must be
reviewed and approved by a registered Professional Engineer and shall be
reviewed or amended for any of the following reasons:
• Whenever the facility has discharged more than 1,000 gallons of oil
in a single spill event;
• Whenever there is a change in facility design, construction,
operation, or maintenance that may affect the facility’s potential for
discharging oil; or
• At least every three years.
State of Maryland regulations concerning the aboveground storage of fuel
oil (COMAR 26.10.01) require that the storage tank, venting, piping, and
metering devices be installed in accordance with appropriate standards of
the National Fire Protection Association and the American Petroleum
Institute. Any underground piping associated with the aboveground
system must comply with COMAR 26.10.03.02.
Each CT/HRSG unit will be equipped with an SCR system that will use 19
percent aqueous ammonia in conjunction with a catalyst bed to reduce
NOx emissions. A complete aqueous ammonia vaporization and injection
system will be provided for each CT/HRSG unit. The system will take
aqueous ammonia pumped from an aqueous ammonia storage vessel,
vaporize the aqueous ammonia, and inject it into the HRSG exhaust gas at
designated locations in the proper proportions. The ammonia will be
delivered by truck to the Site in aqueous form and stored in an onsite
storage tank located within a dedicated concrete containment area. The
installation will include a tanker truck offloading facility located within a
containment berm. The design of the ammonia unloading and storage
area will include appropriate design features required for containment of
any spills; these features will include sufficient spill retention storage to
accommodate the entire storage tank volume.
Storage and handling of aqueous ammonia at concentrations greater than
20 percent is subject to the requirements of EPA’s Chemical Accident
Prevention Provisions (40 CFR Part 68), including the preparation of a
Risk Management Plan (RMP), when quantities exceed 20,000 pounds.
Because the concentration of the aqueous ammonia to be used at the Site
will be less than 20 percent, the facility will not trigger these requirements.
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5.6.3
Solid and Hazardous Waste Handling and Disposal
The Project will generate a solid cake suitable for landfill disposal as result
of the operations of the cooling tower blowdown and recovery
(CTBR)/zero liquid discharge systems. The Project will generate an
estimated 35 tons per day of the solid cake. The solids will be
accumulated and removed by truck daily for offsite landfill disposal.
PPRP recommends a licensing condition requiring that the solid cake be
stored in a way that prevents contact with precipitation and minimizes the
resulting runoff. Mattawoman will test the solid waste from the zero
liquid discharge system prior to disposal to ensure compliance with
applicable State and federal regulations. The solid cake is not expected to
be classified as hazardous (Responses to PPRP Data Request No. 4-10 and
4-11).
Only small quantities of additional solid wastes will be generated by the
Project. Solid wastes will be limited to domestic solid waste and water
treatment solids. Domestic solid wastes will be disposed of by an
approved solid waste disposal contractor. The CTs will require periodic
filter change outs. Dewatered water processing solids will be removed
from the Site by a vendor and taken to an approved offsite disposal or
recycling facility.
Generation of hazardous waste at the Site will be limited to small
quantities of spent solvents, condensation collection from the gas supply
system, and other chemicals. These wastes will be collected onsite and
disposed of offsite in accordance with local, State, and federal regulations.
No hazardous waste will be stored onsite for more than 90 days before
removal. Used oils collected from the oil/water separator, spent
lubricating oils, oily rags, and used oil filters from the CTs will be
transported offsite by an outside contractor and recycled or disposed.
Washdown wastes will be generated from the periodic cleaning of the
turbine blades. These wastes may include alkaline and acidic cleaning
solutions and may contain detectable concentrations of metals. All
washdown wastewater will be collected and tested prior to offsite
disposal.
5.6.4
Construction Activities Near the DRMO Superfund Site
As described in Section 2.3.1, Mattawoman plans to construct the
generator lead line from the Project Site in a northwesterly direction
running adjacent to the right-of-way (ROW) for Brandywine Road. The
line then proceeds to the northeast along the CSXT railroad right-of-way,
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within the 69 kV SMECO corridor, until it reaches a new
substation/switchyard that will be constructed adjacent to the PEPCO
230-kV transmission line. Nineteen transmission poles are proposed to be
located along the generator lead line route; the poles will be
approximately 140 ft high with diameters ranging from 4 to 8 feet, and the
spans between them will be between 700 and 900 ft long. As part of the
generator lead line construction, SMECO will relocate the 69-kV
subtransmission line 39 feet to the east of its current location within the
existing SMECO easement.
To the north of Brandywine Road, the proposed generator lead line will
cross over the north edge of the Brandywine DRMO Superfund site.
According to Response to PPRP Data Request 12-16-1, Mattawoman plans
to install two transmission poles on the DRMO Superfund site and will
use steel H-pilings and screw-pilings to minimize soil displacement and
avoid construction dewatering (see Figure 5-15). Additionally,
Mattawoman will employ drive-hammer and vibratory-hammer
construction installation methods for the pole foundations, and will
construct the pile caps above ground to avoid excavation of onsite soils.
Mattawoman will use timber mats made of natural materials to minimize
construction impacts. These mats will be used for moving and locating
construction equipment.
Although these construction techniques will minimize soil displacement
and construction dewatering, the potential exists for some impacted soil to
be brought to the ground surface along with groundwater generated
during construction activities. As such, prior to the commencement of
transmission line foundation construction activities, PPRP recommends
that Mattawoman be required to adhere to appropriate federal
Occupational Safety and Health Administration (OSHA) and Maryland
OSHA regulations and procedures to ensure worker protection.
Mattawoman should also be required to test soil and groundwater to
properly evaluate whether special protections will be required in the
vicinity of known areas of contamination prior to any excavations that
may occur. The analytical results of the soil and/or groundwater testing
will be compared to relevant EPA standards. Mattawoman shall properly
dispose of excavated soil at a licensed solid waste facility in accordance
with local and State solid and hazardous waste laws, regulations and
guidance. Likewise, groundwater generated during construction activities
shall be contained and tested, and procedures developed and
implemented to ensure that contaminated groundwater is either treated or
disposed according to applicable local, State and federal laws.
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Figure 5-15
Transmission Pole Foundations Proposed for DRMO Site
Source: Mattawoman Response to Data Request No. 12, Attachment 12-39-1.
Under PPRP’s recommended conditions, Mattawoman will prepare a plan
to characterize groundwater in selected monitoring wells prior to
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construction near the DRMO Superfund site property. This plan shall be
submitted to EPA and MDE for review and approval, and to JBA for
consultation. If EPA and MDE determine that Mattawoman’s
construction activities have adversely impacted groundwater remediation
activities at the DRMO Superfund site, Mattawoman must implement
additional mitigation within 30 days of the determination, and
demonstrate satisfactory mitigation of the impact.
5.6.5
Stormwater Management
Mattawoman has indicated that a project-specific stormwater
management (SWM) system will be constructed at the Project Site.
Appendix A-5 of Mattawoman’s CPCN Application contains the SWM
plan. The stormwater management system shall be designed to comply
with the MDE Stormwater Management Regulations (COMAR 26.17.02)
and Prince George’s County Stormwater Management Ordinance.
According to the Mattawoman application for a CPCN, stormwater runoff
from the developed portion of the Site will be directed via infiltration
trenches to an existing SWM pond onsite. Contact stormwater will be
treated as necessary by an oil-water separator before flowing to the SWM
pond, while noncontact stormwater will drain directly to the SWM pond.
From the pond, the water will be discharged to a tributary of
Mattawoman Creek.
Mattawoman will apply for a National Pollutant Discharge Elimination
System (NPDES) permit for stormwater associated with construction
activity. This NPDES permit will also include the water from construction
dewatering operations. Construction stormwater runoff and dewatering
discharge will be directed to the SWM pond before discharge to the
Mattawoman Creek tributary.
In addition, Mattawoman shall comply with Prince George’s County’s
new Watershed Protection and Restoration Program (WPRP), designed to
reduce pollution from stormwater runoff into local waterways, in
accordance with federal and State regulations under the Clean Water Act.
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6.0
CONCLUSIONS AND RECOMMENDATIONS
6.1
AIR QUALITY
The proposed Project will have the potential to emit several types of air
pollutants. The emissions sources evaluated as part of PPRP and MDEARMA’s environmental review included the following:
(a) The main power generating equipment arranged in a combined cycle
configuration (two-on-one power block), including:
i.
Two Siemens H-class version 1.4 (SGT6-8000H) combustion
turbines (CTs) each with a nominal generating capacity of 286
megawatts (MW), fueled exclusively on pipeline quality natural
gas, equipped with low-NOx combustors;
ii.
Two heat recovery steam generators (HRSGs) each with duct
burners rated at 687.3 million British Thermal Units per hour
(MMBtu/hr), fueled exclusively on pipeline quality natural gas and
including a selective catalytic reduction system (SCR) and an
oxidation catalyst;
(b) One auxiliary boiler rated at 42 MMBtu/hr and equipped with lowNOx burners;
(c) One diesel-fired emergency generator rated at 1,490 horsepower (hp);
(d) One diesel-fired fire water pump engine, rated at 305-horsepower (hp);
(e) One 12-cell wet mechanical draft cooling tower;
(f) Four 230 kilovolt (kV) circuit breakers that contain sulfur hexafluoride
(SF6);
(g) Natural gas pipeline components within the facility boundary,
including valves, connectors, flanges, pump seals, and pressure relief
valves; and
(h) Diesel fuel storage tanks associated with the emergency generator and
fire water pump engine.
Based on the information provided in the CPCN application filed in July
2013, supplemental application materials filed in January 2015, additional
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information provided by Mattawoman through responses to data
requests, and independent analyses conducted by the State; PPRP and
MDE-ARMA conclude that emissions from the proposed Project trigger
major Prevention of Significant Deterioration (PSD) requirements for
nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM),
particulate matter less than 10 microns (PM10), particulate matter less
than 2.5 microns (PM2.5), and greenhouse gases (GHG). Because
emissions of these pollutants will be significant, Mattawoman is required
to apply the Best Available Control Technology (BACT) for all sources and
conduct impact assessments to ensure that emissions will not adversely
affect ambient air quality. In addition, the Project triggers the
requirements of Nonattainment New Source Review (NA-NSR) for NOx
and volatile organic compounds (VOCs). Because emissions of these
pollutants will be significant, Mattawoman is required to achieve the
Lowest Achievable Emission Rates (LAER) for all sources.
Air quality dispersion modeling evaluations demonstrate that while
operating within the restrictions included in PPRP and MDE-ARMA’s
recommended licensing conditions (Appendix A), emissions from the
proposed Project are not predicted to cause any significant adverse
impacts to air quality. Specifically, air emissions from the proposed
Project will not adversely affect the attainment of the National Ambient
Air Quality Standards (NAAQS) or PSD increments, and the Project’s
impacts on visibility, vegetation, wildlife, soils, and growth in the region
are likely to be minimal.
In conclusion, evaluation of the Project and its potential emissions indicate
that, if designed and operated in accordance with the recommended
licensing conditions, the Mattawoman Energy Center will meet all
applicable State and federal air quality requirements.
6.2
WATER SUPPLY
Based on an analysis of the dewatering for the proposed Project, MDE
WMA recommends that Mattawoman be granted an appropriation to use
groundwater from the Brandywine Formation to dewater excavations to
support the construction of selected subgrade features within the power
block. MDE WMA recommends the appropriation be granted with the
following amounts:
• Average Daily Use. The annual average water requirement is
60,000 gpd from the Brandywine Formation; and
• Month of Maximum Use. The maximum daily water use is 275,000
gpd for the month of maximum
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MDE WMA believes that withdrawal of 22,000,000 gallons of
groundwater over a 12 month period will not have an adverse impact on
the recharge to the aquifer, surface water, off-site groundwater users, or
the remediation of the nearby Brandywine DRMO VOC plume.
Drawdown that will occur due to dewatering will not be significant
enough to alter the direction of groundwater flow, and drawdown effects
will be temporary and reversible after dewatering is complete. Further,
the dewatering rate of 60,000 gpd will likely not be sustainable over the 12
month dewatering period. However, to ensure drawdown impacts are
monitored and mitigated if the analyses presented herein underestimates
the potential drawdown impacts, MDE WMA recommends the
development of a monitoring plan to be implemented during dewatering
despite the absence of projected impacts associated with the drawdown.
The monitoring plan should include measuring water levels in monitoring
wells during construction dewatering, and if the results of the monitoring
indicate a potential for unacceptable drawdown impacts to occur in
connection with Mattawoman’s construction dewatering, then mitigation
measures should be implemented.
MDE WMA recommends that if the dewatering amounts associated with
the installation of the gas and treated effluent pipelines causes the
threshold limits in COMAR to be exceeded, Mattawoman should submit
an application to the PSC with the requisite information to obtain a
modification to the CPCN to request an increase in the water
appropriation.
Also, a Spill Prevention, Control, and Countermeasures (SPCC) Plan will
need to be developed and implemented in accordance with EPA
requirements to address refueling, storage and containment of hazardous
materials, and spill cleanup and reporting. Proper implementation of the
SPCC plan will protect ground water quality, and prevent accidental
releases to ground water.
6.3
Environmental impacts of the proposed construction and operation of the
Project, associated linear facilities, and substation on biological resources
include potential impacts on streams; rare, threatened, or endangered
species; wetlands; forests; Green Infrastructure and FIDS habitat; and
vegetation. Cumulatively, the Project will directly impact approximately
40 acres of forest, 6 acres of forested wetland, 4 acres of emergent wetland,
and more than and 1 acre of stream and water body habitat.
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Site
Surface Waters and Aquatic Resources. A tributary of Mattawoman
Creek, wetlands, and a stormwater pond are located on the Project Site.
Potential impacts to surface waters from site preparation and plant
construction activities include erosion and sedimentation associated with
site grading, material placement, and access road improvements.
According to Mattawoman’s updated facility plan, site disturbance is
generally limited to approximately 53 acres of open land and 0.27 acres of
pond. Mattawoman plans to minimize impacts to surface waters from site
preparation and plant construction activities through the use of Best
Management Practices (BMPs) and a detailed stormwater management
system (SWM) and erosion and sediment control for the Site.
Mattawoman indicated that it would comply with the requirements of
MDE’s General Permit for Stormwater Associated with Construction
Activity, which includes the development and implementation of a
Stormwater Pollution Prevention Plan (SWPPP) for construction activities.
Mattawoman should also comply with Prince George’s County’s new
Watershed Protection and Restoration Program (WPRP). To ensure that
impacts to surface water and aquatic resources are minimized, PPRP
recommends licensing conditions requiring compliance with Maryland’s
Stormwater Design Manual and the MDE sediment and erosion control
guidelines during construction for water quality control.
Wetlands. Mattawoman anticipates that there will be no significant
impacts to the wetland communities as a result of facility construction or
operation. Although the site disturbance plan indicates that wetland areas
will be avoided, indirect impacts to forested wetlands on and adjacent to
the Site will need to be minimized through approved BMPs and detailed
SWM and erosion and sediment control plans that meet all county and
State requirements. Erosion and sediment control measures will need to
be installed prior to commencement of construction activities and
monitored to protect surface water quality. A Joint Wetlands and
Waterways Permit Application will be required to be submitted to MDE
and the U.S. Army Corps of Engineers (USACE).
Vegetation and Land Cover. Based on information provided in
Mattawoman’s CPCN application, site clearing and construction activities
will occur solely in previously disturbed vegetation communities,
including open land and gravel roads. An existing M-NCPPC approved
Tree Conservation Plan for the Site from the previous land owner
required 8.65 acres of afforestation and 7.66 acres of woodland
preservation. Construction activities should avoid these areas. The
construction of the generator lead line will also require the clearing of
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approximately 0.94 acres of forest clearing along the northwestern edge of
the site along Brandywine Road. Mattawoman has prepared a Forest
Conservation Plan for the site. PPRP recommends licensing conditions
that will protect forests, streams and wetlands, including maintaining
maximum native vegetation on the banks of the unnamed tributary to
Mattawoman Creek and any afforestation or protected areas in the Tree
Conservation Plan for the Site.
Wildlife, Threatened and Endangered Species. DNR WHS has
determined that there are records for RTE species documented in close
proximity to the Project Site that could potentially occur on the Site itself,
where appropriate habitat is present. These RTE species documented
occurrences include the State-threatened Buxbaum’s Sedge, Sandplain
Flax, Racemed Milkwort and the State-endangered Midwestern Gerardia.
Mattawoman conducted additional surveys and the DNR WHS has
accepted the findings of the rare species survey report, which indicated
that no rare species were observed in the Mattawoman project areas
surveyed. Surveys for the spring blooming sedge, Carex buxbaumii (State
Threatened), will be conducted the first week of June 2015. PPRP
recommends licensing conditions that protect any RTE species found on
site. The remaining forest on the Project Site, including FIDS habitat, is
not anticipated to be directly affected by the Project.
Streams. Construction and maintenance of the linear facilities and their
associated rights-of-way (ROWs), and the substation will affect freshwater
streams through trenching, loss of vegetation and shading, bank erosion
and sedimentation during construction, and herbicide contamination
during maintenance activities. The proposed reclaimed water and natural
gas pipelines, and generator lead line cross 11 mapped streams plus
several smaller tributaries and headwaters drainages. Long-term effects
of increased water temperature due to clearing, erosion and runoff from
maintenance treatments also elicit concern. Although Mattawoman plans
to use appropriate BMPs during construction, stream banks and stream
bottoms will need to be restored to their previous function, supporting
local biological communities and providing protection to downstream
Tier II streams. Additionally, restored areas should be monitored and
treated for several years to ensure the re-establishment of sustainable
native species communities in and adjacent to the streams.
Wildlife and Rare, Threatened and Endangered Species. The proposed
reclaimed water and natural gas pipelines, and substation are located
within Biodiversity Conservation Network areas and areas that have been
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identified as potential habitat for Forest Interior Dwelling Bird Species
(FIDS) by the DNR WHS. The WHS has accepted the findings of
Mattawoman’s rare species survey report completed in the fall of 2014,
which indicated no rare species were observed in the Mattawoman project
areas surveyed. Surveys for the spring blooming sedge, Carex buxbaumii
(StateThreatened), are recommended for the first week of June 2015.
Mattawoman submitted a request for the new substation site to WHS in
April 2015, and will conduct a listed species survey of the revised
substation site in June 2015. Following recommendations made by WHS
for the protection of RTE plant species, a management plan for any RTE
species potentially affected by construction should be required. DNR
Fisheries has noted the presence of State-threatened Flier, within the
overall Zekiah Swamp watershed. Mitigation of any impacts to RTE
species is recommended.
Wetlands. Wetlands are prevalent along the proposed reclaimed water
and natural gas pipeline routes, and substation site, and are associated
with the stream systems. The proposed natural gas pipeline for the
Project crosses the headwaters of Mattawoman Creek, two tributaries to
Wolf Den Branch, two tributaries to Zekiah Swamp Run, and three
headwater ravines that drain into Jordan Swamp. Both Zekiah Swamp
Run and Jordan Swamp are designated as Wetlands of Special State
Concern (WSSC). Construction of the gas pipeline will result in
approximately 10 acres of wetland/water body impact. Of these,
approximately 6.8 acres are temporary and 2.7 are permanent. WSSC’s
provide habitat for RTE species; are unique natural areas; or contain
ecologically unusual natural communities and receive enhanced legal
protection under COMAR 26.23.06. Mattawoman has not provided
specific construction details regarding the headwater crossings of the
WSSC, but plans to trench a majority of the gas pipeline. Mattawoman
states that the only permanent impacts that will result are the permanent
conversion of 2.82 acres of forested wetland in the permanent
maintenance easement, and that these areas will be maintained as
emergent or scrub/shrub wetlands following construction. PPRP
concludes that, while there may be no overall decrease in wetland area,
the functionality of the wetland would be drastically changed owing to
the removal of the larger shade trees that will thereby impact the wildlife
and understory plant community. Forested wetlands also provide
benefits such as soil stabilization. Approximately 0.02 acre of forested
wetland within the substation site that will need to be permanently filled.
Mattawoman proposes to mitigate this permanent loss of the filled
wetland by creating wetlands along the same drainage, outside the
proposed limits of disturbance, at a ratio approved by MDE, and protect
stream channels during construction to minimize sediment erosion.
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However, the streams on the site are the headwaters of a Tier II segment
of Piscataway Creek. The loss of 4.6 acres of upland forest in the
headwaters area cannot be addressed by the proposed onsite mitigation.
Green Infrastructure. The proposed reclaimed water and natural gas
pipeline corridors lie almost entirely within Green Infrastructure (GI) and
FIDS habitat, and the gas pipeline will widen the existing gaps associated
with the PEPCO/SMECO transmission line ROW. As proposed, the gas
pipeline will require approximately 16 acres of upland forest, and 5.82
acres of forested wetlands to be cleared. This area is located in a Green
Infrastructure Hub, where PPRP recommends a post-construction
watershed. Constructing the generator lead line, substation and the tie-in
will impact approximately 17 acres of forest and 0.04 acre of forested
wetland. DNR requires mitigation for the clearing and cutting of forests
under the Forest Conservation Act (FCA). To minimize impacts to FIDs
habitat, the removal or disturbance of forest habitat during April-August, the
breeding season for most FIDS is not recommended. Seasonal restrictions
may be expanded to February-August if certain early nesting FIDS (e.g.,
Barred Owl) are present. Additionally, the use of HDD to construct the gas
pipeline at the Mattawoman Creek and Jordan Swamp crossings, or an
alternative route for the last approximately 1-mile segment following
Poplar Hill Road and Gardiner Road would further minimize impacts to
FIDS habitat.
Scenic River. The Project will affect the natural resources of the
Wicomico-Zekiah Swamp Scenic River watershed. Without mitigation,
there will be permanent impacts that include the loss of Green
Infrastructure forest, displacement of wetlands soils and conversion of
dozens of forested wetlands to herbaceous wetlands, alteration of
numerous stream bottom and bank areas, and loss of use of State
parkland. Each individual impact diminishes the "natural values" of the
river system that are protected by the Scenic River Act.
Recommendations
General recommendations encompass existing Maryland policies and
regulations that ensure no net loss of wetlands and forest areas, and no
degradation of high quality streams (e.g., Non-Tidal Wetlands Act, Forest
Conservation Act, and Scenic and Wild River Act). Moreover, these
recommendations follow Maryland’s Scenic and Wild River Act that
instructs State and local agencies to use any means necessary to not only
protect but also enhance the qualities of the designated river systems,
including the Wicomico River and Zekiah Swamp. Avoidance is the most
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effective approach to protecting sensitive biological resources. Where
avoidance is not feasible, minimizing disturbances through the utilization
of enhanced best management practices and alternative construction
techniques such as horizontal directional drilling (HDD) under streams or
wetlands is recommended. Minimization, however, does not negate the
need for mitigation of the disturbances to ecologically sensitive areas.
In particular, the disturbance to wetlands, streams, and forests from the
natural gas pipeline construction in the extremely sensitive Zekiah Swamp
watershed will have to be mitigated, preferably with in kind replacement
within the watershed itself. The Scenic and Wild Rivers Act reinforces
and gives added strength to the non-tidal wetlands and forest
conservation regulations, and does not provide any utility exemptions.
Specific recommendations include licensing conditions on any CPCN
issued for construction of the proposed Project that require:
•
Minimizing impacts to FIDS habitat, by not removing or disturbing
forest habitat during April-August, the breeding season for most
FIDS, and expanding these restrictions to February-August if
certain early nesting FIDS are present.
•
Tree roots and stumps should be left in place, except where such
roots and stumps interfere with pipeline trenches, access roads, or
other physical components of the linear facilities. Additionally,
removed trees should be cut and windrowed along the edge of the
ROW, outside of wetland areas, to create wildlife habitat where
acceptable to the property owner. If brush is shredded or chipped,
it may be distributed on the cleared permanent ROW only as a
ground cover to stabilize the soil surface, but the depth shall not
exceed two (2) inches in wetlands, buffers and floodplains, or 4 to 6
inches in upland areas.
•
The total acreage of trees removed for construction of the proposed
Project should be mitigated according to the Forest Conservation
Act specifications. This mitigation should be accomplished by
planting native trees in a restoration location or location(s) that will
be entered into a conservation easement, preferably within the
same watershed in which the loss was incurred. Prior to
conducting any tree removal activities, Mattawoman will file a
Forest Stand Delineation and a Forest Conservation Plan with the
MDNR Forest Service. All restored areas should be monitored for
at least 5 years to ensure survival of plantings, and annually
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restocked to the planned density to compensate for seedling
mortality.
•
All clearing of forest from wetlands areas that will be retained as
herbaceous wetlands shall be mitigated by restoration of an equal
or greater amount of forested wetland within the same watershed.
Any wetland area that is completely drained or destroyed should
be mitigated according to the provisions of the Non-Tidal Wetlands
Act and as approved by MDE.
•
Managed conversion of the cleared wetland areas to herbaceous
wetlands containing sustainable populations of native species
similar to those found in existing wetlands in the watershed should
be required.
•
No disturbance shall occur to Wetlands of Special State Concern or
their 100-foot buffers by using HDD, with approval from MDE, to
avoid all vegetation removal and/or disturbance.
•
Monitoring restored wetlands and reforested areas to ensure the
establishment of sustainable native species communities including
RTE species, where present.
•
Avoid construction during critical reproductive periods for the
plants and animals of the wetlands ecosystem.
•
Soil removed during trenching activities through wetlands should
be used to refill the trench when the pipe is in place, and soil
consistency, density, and elevation in these wetlands areas should
be restored to pre-construction conditions as soon as possible after
pipe placement.
•
Enhanced best management practices should be used for all
construction in or near streams and drainage channels, such as
double silt fences and redundant stormwater runoff controls,
construction of earth dikes in appropriate locations, sediment traps,
use of super silt fences, stabilizing disturbed areas as quickly as
possible, use of sandbag dikes in streams and along pond edges
where necessary, and the use of timber mats or other temporary
bridge systems for crossing over streams where practicable, and
converting silt traps to permanent features as soon as practicable.
•
All stream bottoms and banks that are trenched during
construction should be restored to their original contours and soil
MD PPRP
6-9
composition, stabilized, and monitored for a period of years to
ensure, and address as necessary, any erosion, scouring, or other
deterioration.
6.4
•
Wetlands within the permanent gas pipeline ROW shall not be
mowed, and there shall be an additional 100-ft-wide no-mow zone
established within the permanent ROW adjacent to all wetlands
and streams. Any necessary vegetation removal in these areas will
be done manually or by MDE-approved herbicide treatment.
•
Areas within the ROW maintained as grasses and forbs should not
be mowed during the breeding season for ground nesting birds
from April through August of each year. If mowing is necessary
outside of the May through August breeding season, mowing
should be to a height of no less than 10 inches, with the exception
of areas under special management for invasive species control.
•
Use of HDD at all stream and tributary crossings that affect the
Zekiah Swamp System, wherever feasible, and restore and
maintain the crossings in the best possible ecological condition
through long-term integrated vegetation management plans.
•
MDE- approved contingency plans to address inadvertent releases
of drilling fluid that occur where HDD operations are conducted.
Mattawoman estimates that the average annual construction workforce
would be approximately 275 employees over an approximately three-year
period. During the construction period, construction worker payrolls are
expected to inject substantial income into the State’s economy. Postconstruction, approximately 30 employees would operate the facility with
a payroll (including benefits) approaching $3.5 million annually. Annual
operations and maintenance (O&M) expenditures on goods and services
are expected to be $6.35 million. Overall, the economic impacts from
project construction and operation are small relative to the Maryland and
Prince George’s County economies. Still, both the State and county would
benefit economically from the Project
During construction, the Project would not appreciably affect population
or the demand for housing in Prince George’s County because the
construction labor force is expected to commute to the Site on a daily basis
rather than relocate or reside in short-term transient accommodation. The
MD PPRP
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addition of 30 O&M employees would have no effect upon population
and housing conditions in the post-construction period.
Permanent land use impacts associated with construction and operation of
the Project are expected to be confined to the interior of the 88-acre parcel.
Approximately 28 acres would host permanent facilities. Additional land
would be occupied during construction for laydown, parking and project
management. PPRP has recommended a licensing condition requiring
Mattawoman to design the facility in substantial conformity with the Site
Plan drawings reviewed by the Prince George’s County Planning
Department.
Part of the Mattawoman Energy Center property is within the Joint Base
Andrews Outer Horizontal Surface zone (Zone F), with the rest within the
Approach-Departure Clearance Surface (Zone C). Prince George’s County
ILUC regulations forbid the issuance of building permits for any structure
exceeding the height of any imaginary surface. The tallest structures of
the Project are 100 feet AGL and appear to be compatible with the
county’s ILUC regulations.
The Mattawoman Energy Center would be located directly north of the
Globecom Receiver Site. The USAF, concerned with microwave and high
frequency communications interference, radio frequency interference, and
potentially other conflicts that could impact missions affecting national
security, is independently reviewing the Project for potential impacts.
Mattawoman’s proposed reclaimed water pipeline would be buried under
existing road ROWs for most of its length. The Project’s underground
natural gas pipeline would be constructed mostly within a CSXT railroad
ROW and a PEPCO transmission line corridor. During construction,
temporary land use impacts from trenching and installation would be
confined to a narrow corridor adjacent to the pipeline route. Postconstruction, land would be restored to its previous state. PPRP has
concluded that construction and operation of the reclaimed water and
natural gas pipelines would have no direct or indirect effect upon land use
along its proposed route.
The Project’s generator lead line would mostly parallel the CSXT rail line
to a PEPCO 230-kV transmission corridor that connects to the Burches Hill
substation. Easements would be required from nine property owners.
The northernmost of these is protected under a MALPF easement. PPRP
has recommended an initial licensing condition requiring Mattawoman,
prior to construction of the generator lead line, to certify to PPRP and the
MD PPRP
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PSC that it has obtained approval for an Overlay Easement from the
MALPF Board of Trustees.
During construction, Prince George’s County would see an increase in
traffic on roads leading to the construction site, particularly during the
peak construction period when approximately 645 construction workers
are onsite. To quantify traffic impacts, Mattawoman commissioned a TIS
which revealed that nearby intersections of MD 381 with local roads
would operate at an acceptable LOS after the facility is operational,
although one major intersection west of Brandywine would operate at an
unacceptable LOS due to background traffic growth not related to the
Project. However, in addition to congestion at major intersections, the
LOS for some turning movements onto Brandywine Road from Missouri
Avenue and from the site access driveway would be adversely affected in
the peak construction period during the evening peak hour. The SHA
agrees that the Project would have a negligible long-term impact to traffic
operations within the study area, but also concluded that impacts to
nearby intersections during construction would be substantial.
Mattawoman revised its TIS in a Supplemental Filing which complied
with SHA’s request for point-by-point responses and a construction plan.
Based on the information provided, the SHA concluded that the
comments included in its December 17, 2014 review letter were
adequately addressed, and that the proposed TMP was acceptable subject
to refinement during implementation. PPRP has included a
recommended licensing condition that addresses the SHA’s concerns.
Transport of oversize /overweight equipment to the Project Site could
also affect traffic during construction. PPRP has recommended an initial
licensing condition requiring Mattawoman to comply with all permit
requirements for transport of oversize or overweight loads on State
highways and Prince George’s County roads, and to obtain appropriate
approvals, as necessary.
The reclaimed water pipeline would mostly occupy the ROWs of two
county roads and two State roads between the Piscataway WWTP and the
Project Site. The pipeline would also cross under a county road, two State
highways, a federal highway and the CSX Pope’s Creek Secondary
railroad line. The natural gas pipeline would be mostly within
transmission line and railroad ROWs, but would cross three county roads
in Charles County and two in Prince George’s. The generator lead line
would be within or adjacent to public roads and rail corridors for most of
its length, crossing MD 381, three county roads and the CSX rail corridor.
The Mattawoman Energy Center would connect to public water and
sewer lines under Brandywine Road near the entrance to the Site. PPRP
MD PPRP
6-12
has recommended a licensing condition requiring Mattawoman to obtain
appropriate utility permits from the Prince George’s County Department
of Public Works, Charles County, and the Maryland State Highway
Administration to construct the reclaimed water and natural gas pipelines,
and the generator lead line. For pipeline construction with SHA ROWs,
Mattawoman to submit to the SHA a Maintenance of Traffic (MOT) plan
that details work zone impact management strategies on State highways
that will be affected by the Project.
PPRP expects the Project will have only a minor visual impact on the
general area. It has recommended a licensing condition requiring
Mattawoman to establish a landscape buffer along Brandywine Road to
provide screening for nearby residential lots and motorists. Visual
impacts from the proposed substation would be mitigated by a landscape
plan, which in Prince George’s County is a required element of all detailed
site plans.
Outdoor lighting for the Project could adversely affect nearby properties
through light trespass or add luminance to the night sky. Because a
landscape buffer would be established along Brandywine Road, light
trespass onto nearby properties is not expected. Skyglow will be
minimized through the selection of appropriate luminaries and
supporting structures. PPRP has recommended a licensing condition
requiring Mattawoman to develop a lighting distribution plan to mitigate
intrusive night lighting and avoid undue glare onto adjoining properties.
During construction, revenues from taxes on construction worker wages,
income taxes on indirect and induced employment incomes, and sales
taxes on consumption expenditures would accrue to Maryland and local
governments. Fiscal post-construction benefits would include personal
income tax revenues to the State and Prince George’s County from direct,
indirect and induced employment gains, and corporate income tax
revenues from the operating company. Depending upon the proportion
of goods and services procured from Maryland industries, Mattawoman
estimates state sales tax revenues could increase. The most significant
revenue impact to Prince George’s County would be from property taxes.
Mattawoman estimates that real and personal property taxes would
average approximately $3 million over the first 20 years of Project
operation. Additional property tax revenues would accrue from the
generator lead line and substation.
Construction could marginally affect public services such as fire, rescue,
and police services in Prince George’s County, particularly when
MD PPRP
6-13
construction traffic is added to other commuting traffic. Because the
Brandywine Volunteer Fire Department is a combined career/volunteer
system, an accident at the Mattawoman Site during construction or
operation could temporarily strain local resources. PPRP has
recommended a licensing condition requiring Mattawoman to contact the
Prince George’s County Fire and Emergency Medical Services Department
and the Brandywine Volunteer Fire Department to address Site safety and
EMS coverage, establish timely response options and facilitate emergency
vehicle access throughout the Site in case of an accident or injury. Where
existing emergency response capabilities are determined to be inadequate,
Mattawoman should assist these organizations through contributions,
training and/or general support. The projected permanent workforce is
not expected to have an adverse effect upon public services in the county.
The net fiscal impact of the Project on Prince George’s County is expected
to be favorable.
Most potential effects on cultural resources would be within the Project
property, although some visual and noise impacts could extend beyond
the Project boundaries to nearby cultural resources. Post-construction
impacts on cultural resources would be confined to the Project property.
The Mattawoman property has not been the subject of previous
archeological, architectural or historical investigations. However, the
majority of the Project Site has been extensively cleared and graded and
has little or no archeological potential. The MHT concurs that the Project
would have no effect upon historic properties.
Mattawoman’s reclaimed water and natural gas pipelines would be
constructed mostly within existing ROWs that have been previously
disturbed. The Historic Preservation Section of the Prince George’s
County Planning Department has noted that several historic resources
located on Accokeek Road are very close to the ROW and must be
avoided during construction. The MHT reviewed the proposed linear
facilities corridors and recommended that Phase I archeological survey
work would be needed for the 0.9-mile section of the proposed natural gas
pipeline alignment that exits the PEPCO corridor north of the Jordan
Swamp. Following a review of a cultural resources report of the
“Greenfield Segment” of the pipeline corridor, MHT concurred that the
affected area possesses no archeological research potential and that
further archeological investigations are not warranted. After reviewing
the archeological and historic aspects of the generator lead line route, the
MHT concluded that no cultural resource investigations are warranted for
this element of the Project. Because MHT has not yet issued a formal
determination of effect on historic properties for the relocated substation,
MD PPRP
6-14
PPRP has recommended an initial licensing condition that addresses the
protection of cultural resources within the proposed substation parcel.
Both the reclaimed water and natural gas pipelines intersect Booth’s
Escape Scenic Byway, part of the SHA’s Scenic Byway Program. The
natural gas pipeline would be partly within the boundaries of the
Southern Maryland Heritage Area (SMHA), one of 13 certified heritage
areas in the State. The Project would have no adverse effect upon either of
these heritage resources.
6.5
NOISE IMPACTS
Using the source noise information provided by the applicant, PPRP
prepared screening-level estimates of the sound pressure levels that
would result at various receptors surrounding the Mattawoman Energy
Center Site when the proposed facility is operating at full load. The
proposed Project is not expected to exceed the nighttime noise standard of
55 dBA with the exception of Receptor 4. At this location, the predicted
noise level is higher, but this location is an industrially zoned property.
The proposed Project will not exceed the applicable noise limit of 75 dBA
in this area. This conclusion takes into account the existing noise levels
that Mattawoman measured in its baseline assessment of existing
conditions.
It should be noted that the adjacent properties closest to the power block,
to the east and south of the Mattawoman Site, are currently zoned as open
space and are undeveloped. This zoning allows for low-intensity
residential use (5-acre lots), and is intended to promote the economic use
and conservation of land for agriculture, natural resource use, large-lot
residential estates, and non-intensive recreational use. It is likely that
operation of the proposed Mattawoman Project would create noise levels
at the eastern and southern property boundaries that would exceed the
target level for residential noise impacts. While this would not constitute
regulatory non-compliance as long as the land remains undeveloped, the
presence of the proposed power plant may limit future uses of the
adjoining parcels.
PPRP concludes that the Mattawoman Project will not cause significant
noise impacts provided it meets the recommended licensing conditions.
After the facility begins operation, Mattawoman should conduct postconstruction noise monitoring to verify that the facility is operating in
compliance with applicable noise regulations.
MD PPRP
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7.0
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Environmental Review of the Proposed Mattawoman Energy Center

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