Getting a Handle on the Bacterial Pollution and Septic System

Getting a Handle on the Bacterial Pollution and
Septic System Troubles in Martin County
June 18, 2015
Florida Stormwater Association Annual Conference
Dianne K. Hughes, Senior Ecosystem Specialist
Ecosystem Restoration & Management Division
Martin County Engineering Department
and
Rhett Keene, PE, LEED AP
Director of Engineering
CAPTEC Engineering, Inc.
Where is Martin County?
The St. Lucie River & Estuary
Martin County – who are we?
• Population = 149,236
• Phase II MS4
• Area = 753 square miles
• (543 square miles land; 210 square miles water)
• Twenty-five percent of County in conservation
• Waterways are the lifeblood of our community
• One out of every 10 jobs in Martin County is
marine-related
What is the Problem?
• Elevated bacteria levels present in the estuary
beginning in November 2012
• Martin County Health Department issued
Health Advisories to avoid contact with water
• Poor water quality is a serious concern to the
citizens of Martin County
What do we know?
St. Lucie River Estuary Bacteria Sampling Results
450
400
350
cfu/100 ml
300
Roosevelt Bridge
250
Leighton Park
200
East of Bessey Creek
Good Range
150
100
50
0
11/5/2012
12/5/2012
1/5/2013
2/5/2013
3/5/2013
4/5/2013
5/5/2013
5/5/2015
4/5/2015
3/5/2015
2/5/2015
1/5/2015
12/5/2014
11/5/2014
10/5/2014
9/5/2014
8/5/2014
7/5/2014
6/5/2014
5/5/2014
4/5/2014
3/5/2014
2/5/2014
1/5/2014
12/5/2013
11/5/2013
10/5/2013
9/5/2013
8/5/2013
7/5/2013
6/5/2013
5/5/2013
4/5/2013
3/5/2013
2/5/2013
1/5/2013
12/5/2012
11/5/2012
cfu/100 ml
Post Lake Okeechobee Discharges
and Wet Season Runoff
St. Lucie River Estuary Bacteria Sampling Results
3500
3000
2500
Roosevelt
Bridge
2000
Leighton
Park
1500
East of
Bessey Creek
1000
Stuart
Sandbar
500
Poor
0
Why do we need to do something
about it?
• Public health and safety
• Total Maximum Daily Load
• FDEP considering adoption of a statewide
TMDL for fecal coliform with pollutant
reductions for bacteria impaired
waterbodies
• Local economy
Are septic tanks the source of
the problem?
• Sucralose sampling within the estuary
detected at several locations
• Not a smoking gun – sucralose survives
wastewater treatment process
• Martin County reuses treated
wastewater for irrigation
What don’t we know?
What should we do?
• Bacterial DNA testing is our next step
• Worked with FDEP to coordinate St. Lucie
River Bacteriological Technical Advisory Team
• Martin County requested assistance from
FDEP to determine source(s) of bacteria within
our waterways
• Approached the Board in November 2013 for
funding for projects to determine source of
pollution and potential costs for any sewer
conversions
Board Approved Funding
• CAPTEC Engineering, Inc. (CAPTEC) selected to update
the 2001 Septic System Elimination Study
• Cardno Entrix selected to perform a Bacterial DNA
Analysis
• FAU – Harbor Branch Oceanographic Institute selected
to perform an Onsite Treatment and Disposal System
Study at 2 locations within the watershed
• Public Resources Management Group, Inc. selected to
prepare a Financial and Rate Assistance Report
Initial Microbial Study Design
• 6 sites within the watershed
• Bacteria indicator
– Enterococci (tested at two sites)
• Human indicators
– Human Bacteriodetes
– Human Bacteriodetes – EPA
•
•
•
•
Horse Bacteriodetes
Cow Bacteriodetes
Dog Bacteriodetes
Bird Fecal
DNA Biomarker Sampling Locations
Initial Study Results
Modified Microbial Study Design
• FDEP and County staff performed sampling
• 14 tributary and river sites selected
• Bacteria indicators
o E. coli
o Enterococci
o Fecal coliform
• Human indicators
o Bacteriodales – HF183
• Chemical indicators
o Acetaminophen
o Sucralose
Indicator Source Tracking Sampling Locations
Study Results – June, 19, 2014
Study Results – July 22, 2014
Study Results – August 21, 2014
Results and Recommendations
• All American Ditch and Golden Gate showed
evidence of human wastewater bio-markers,
elevated bacteria levels and chemical markers
• Sampling performed on outgoing tide as close
to low tide as possible
• Dry season sampling completed May 12, 2015
• Conduct storm event monitoring
• Conduct a Walk the WBID
How many septic tanks potentially
impact the St. Lucie Watershed?
• Martin County Utility Service Area
– 16,209*
• City of Stuart – 1,300
• City of Port St. Lucie – 22,887
*These numbers do not include Hobe Sound, Jupiter Island,
Indiantown or areas outside the Martin County Utility Service Area.
Martin County
Septic Tank Areas
and 4 Wastewater
Treatment
Package Plants
located within the
Martin County
Service Area
Septic Tank Elimination Study
•
•
The purpose of the Septic Tank Elimination Study was
to determine the priority of removing the existing
septic systems.
A preliminary analysis was performed to estimate the
cost of replacing the septic systems with three (3)
alternative systems:
•
Gravity Sewer System
•
Air Vacuum System
•
Grinder Pump System
Locations
Methodology
Each of the Communities was evaluated for their peak design flow and then ranked as a priority to
replace the septic systems with a public sanitary sewer collection system. The ranking factors include:
1) Population Density for Loading Concentrations
2) Availability of a Public Water System – Potable Water System
3) Classification of Surface Water
4) Proximity to Surface Waters
5) Location of the Community in Relation to the 100-year Flood Plain – FEMA Flood Plain
6) Depth of the Ground Water Table
7) Soil Conditions of the Drain Field – Soil Type
8) Age of the Surface Water Management System
9) Nitrogen/Nitrate Load Contribution to the Groundwater
10) Verified Presence of Human Fecal Markers – Human Biological Markers
Population Density
• The existing and future population for each
subdivision was estimated by the parcel count
and the density allowed by the zoning
classification.
•
•
•
4 points assigned for low density (< 2 upa)
8 points for medium density (2-5 upa)
12 points for high density populations (> 5 upa)
Potable Water Systems
• The availability of a public water system was included
in the study as a primary health concern due to
potential contamination to the water supply in areas
that primarily utilize onsite wells for drinking water in
conjunction with a septic system.
• 4 points for public water system
• 8 points for both systems
• 12 points for an onsite wells
Classification of Surface Water
• Class II waters are regulated to maintain water quality
standards for shell fish harvesting and propagation.
• Class III waters are regulated to maintain a healthy
environment for wildlife, fishing, and recreational
activities.
• 4 points for areas without a boundary along Class II
or III waters
• 8 points for areas abutting Class III waters
• 12 point for areas abutting Class II waters
Proximity of Surface Waters
• Due to the potential of contamination from septic tank
drain fields adjacent to surface waters, the
Communities were evaluated by their proximity to
major water bodies.
• 12 point for areas abutting major water bodies
• 8 points for areas with a connection to above
• 4 points for areas located inland, no connection
FEMA Flood Plain
• Septic tanks located within the 100-year flood plain
introduce a potential safety hazard to surrounding
waters.
• The FEMA Flood Insurance Rate Maps for Martin
County were used to determine which Communities
are prone to flooding during the 100-year storm event.
• 4 points for areas located outside the flood plain
• 8 points for areas < 50% in the flood plain
• 12 points for areas > 50% within the flood plain
Ground Water Table
• Per FAC Chapter 64-E6 design criteria, the septic tank
drain fields should be installed in areas with a minimum
depth of 48 inches to the ground water table.
• SFWMD and the USDA Soil Conservation Service soil
survey for Martin County were utilized to determine
the groundwater table depth for the Communities.
• 4 points for areas with > 48 inches depth
• 8 points for areas with 36 - 48 inches depth
• 12 points for areas with < 36 inches depth
Soil Limitations
• The National Resource Conservation Service (NRCS) Soil
Survey of the Martin County Area, Florida (USDA, SCS
1981) was used to determine the soils types located
within the Communities.
• The NRCS Soil Survey, Table 12-Sanitary Facilities,
provides descriptive terms for the restrictive soil
features suitability for use with Septic Tank Absorption
Fields.
• 4 points for soils with slight limitations
• 8 points for soils with moderate limitations
• 12 points for soils with severe limitations
Surface Water Management System
• The SFWMD water quality standards for stormwater
runoff became more stringent in 1978 and again in
1988.
• The plat date was used to determine the time frame
when a community’s stormwater system was
constructed.
• 4 points for areas platted after 1988
• 8 points for areas platted between 1978 and 1988
• 12 points for areas platted before 1978
* Areas with multiple platted dates were weighted by the area platted and
the date of the recorded plat.
Nitrogen/Nitrate Load Contribution to
Groundwater
• The March 2007 Wekiva River Basin Nitrate Sourcing
Study Phase 1 Report, prepared for the St. Johns
River Water Management District and Florida
Department of Environmental Protection, assumes
approximately 14 lbs of nitrogen per year from each
septic tank
• A nitrogen contribution factor was then prorated
with the highest contribution (Hibiscus Park –
18,886 lbs/year) receiving 12.0 points and the
lowest contribution (Rosewalk / Galleon Bay – 350
lbs/year) receiving 0.22 points
Verified Presence of Human Fecal
Source Bio-Markers
• The results of the FDEP St. Lucie River
Microbial Source Tracking Wet Season Study,
dated November 7, 2014 was used for this
ranking criteria
• 0 points assigned to areas where human biomarkers were not found
• 12 points assigned to areas where human biomarkers were found
Ranking Summary
Summary of Costs / Ranking (Total)
Moving Forward
• Board of County Commissioners workshop
scheduled for Fall 2015 with presentations to the
Board on the following:
• Final findings of Microbial Source Tracking
Study
• Septic System Elimination Report Update
• Financial and Rate Assistance Report
• A Septic to Sewer Program Proposal
What is Next?
• Establish criteria/programs for potential
assessments (voluntary areas get priority)
• Implement schedule for improvement areas,
based upon current rankings
• Obtain grant funding for septic to sewer
conversion
• Notify public of pending assessments (2-5 year
advance warning)
• Continue HF183 sampling program for other
Communities (and adjust rankings)
Questions?