Wastewater Treatment Facilities Upgrade Project Plan

Project Plan
Wastewater Facilities Upgrades
Prepared for:
City of Alma, MI
525 E. Superior Street
PO Box 278
Alma, MI 48801-0278
May 2010
Prepared by:
127 S. Main St | Mt. Pleasant, MI 48858 | p (989) 772-2138 | f (989) 773-7757
09M0017
Table of Contents
I.
Introduction ........................................................................................................................................... 1
II.
Study Area Characteristics .................................................................................................................... 1
A.
Service Area ...................................................................................................................................... 1
B.
Study Area ........................................................................................................................................ 3
C.
Economic Characteristics .................................................................................................................. 4
D.
Growth .............................................................................................................................................. 5
E.
Existing Facilities.............................................................................................................................. 5
1.
General .......................................................................................................................................... 5
2.
Wastewater Treatment Plant ......................................................................................................... 5
3.
NPDES Permit .............................................................................................................................. 6
4.
Biosolids ....................................................................................................................................... 6
5.
Collection System ......................................................................................................................... 7
6.
Infiltration and Inflow ................................................................................................................... 7
7.
Wastewater Characteristics ........................................................................................................... 7
8.
Septage Receiving Facilities ......................................................................................................... 8
9.
Major Dischargers ......................................................................................................................... 9
10.
Industrial Pretreatment Program ............................................................................................... 9
11.
Dry and Wet Weather Flows ..................................................................................................... 9
III.
Summary of Studies, Inspections, and Analyses .............................................................................. 9
A.
Sewer System Study ......................................................................................................................... 9
B.
Smoke Testing ................................................................................................................................ 10
C.
Field Review/Manhole Inspections ................................................................................................. 10
D.
Collection System Video Taping .................................................................................................... 10
E.
Home & Business Inspections ........................................................................................................ 11
F.
Flow Metering and Analyses .......................................................................................................... 11
G.
Need for Project .............................................................................................................................. 15
1.
Compliance Status ...................................................................................................................... 15
2.
Orders .......................................................................................................................................... 15
3.
Water Quality Problems .............................................................................................................. 15
H.
Projected Needs for the Next 20 Years ........................................................................................... 15
I.
Future Environment without the Proposed Project ......................................................................... 16
J.
Population Data ............................................................................................................................... 16
K.
Environmental Setting .................................................................................................................... 16
1.
Cultural Resources ...................................................................................................................... 16
2.
The Natural Environment............................................................................................................ 16
IV.
V.
Development of Alternatives .......................................................................................................... 19
Analysis of Alternatives ...................................................................................................................... 19
A.
Alternative 1- Provide Upgrades to Transport and Treat I/I ........................................................... 19
B.
Alternative 2 - Correct Some Footing Drains and Increase Collection System Capacity ............... 22
C.
Alternative 3 – Do Nothing ............................................................................................................. 24
D.
Alternative 4 – Optimum Utilization .............................................................................................. 24
E.
Alternative 5 - Regionalization ....................................................................................................... 24
F.
Analysis of Principal Alternatives .................................................................................................. 24
VI.
Technical and Other Considerations ............................................................................................... 25
A.
Infiltration and Inflow ..................................................................................................................... 25
B.
Sludge and Residuals ...................................................................................................................... 25
C.
Industrial Pretreatment .................................................................................................................... 25
D.
Growth Capacity ............................................................................................................................. 25
E.
Areas without Sewers ..................................................................................................................... 25
F.
Reliability ........................................................................................................................................ 25
G.
Alternative Sites and Routings ........................................................................................................ 26
H.
Combined Sewer Overflows ........................................................................................................... 26
I.
Contamination at the Project Site.................................................................................................... 26
VII.
Selected Alternative ........................................................................................................................ 26
A.
Relevant Design Parameters ........................................................................................................... 26
B.
Controlling Factors ......................................................................................................................... 27
C.
Sensitive Features ........................................................................................................................... 27
D.
Evaluation of Environmental Impacts............................................................................................. 27
1.
Impacts Resulting from Construction and Operation of Selected Alternative ............................ 27
2.
Project Impacts............................................................................................................................ 28
3.
Indirect Impacts .......................................................................................................................... 28
4.
Cumulative Impacts .................................................................................................................... 28
E.
Mitigation ........................................................................................................................................ 28
VIII.
Schedule .......................................................................................................................................... 29
A.
Staging of Construction .................................................................................................................. 29
B.
Authority to Implement the Selected Alternative ........................................................................... 29
C.
User Costs ....................................................................................................................................... 30
D.
Public Participation ......................................................................................................................... 30
List of Tables
Table 1: Major Employers ............................................................................................................................ 4
Table 2: Minority Population and Income Data............................................................................................ 4
Table 3: Pump Station Characteristics .......................................................................................................... 7
Table 4: Summary of WWTP Flows and Characteristics (2009) ................................................................. 8
Table 5: Inflow and Infiltration..................................................................................................................... 9
Table 6: Potential Sources of Inflow from Smoke Testing ......................................................................... 10
Table 7: Summary of Manhole Inspections ................................................................................................ 10
Table 8: Dry Weather Flow Analysis ......................................................................................................... 12
Table 9: Analysis of 25 Year, 24 Hour Peak Flow ..................................................................................... 13
Table 10: WWTP Effluent .......................................................................................................................... 15
Table 11: Population Summary .................................................................................................................. 16
Table 12: Alternative 1 ............................................................................................................................... 20
Table 13: Alternative 2 ............................................................................................................................... 22
Table 14: Proposed Design Criteria ............................................................................................................ 27
Table 15: Projected Sewer Bill ................................................................................................................... 30
List of Figures
Figure 1: Service Area .................................................................................................................................. 2
Figure 2: Study Area ..................................................................................................................................... 3
Figure 3: 2009 Recorded Daily Flows .......................................................................................................... 8
Figure 4: Inadequate Sewer Capacity ......................................................................................................... 14
Figure 5: Alternative 1 Upgrades ................................................................................................................ 21
Figure 6: Alternative 2 Upgrades ................................................................................................................ 23
Appendices
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
Characteristics of Study Area
Water Resources of Study Area
Existing Wastewater Facilities
NPDES Permit
Focus Areas – Footing Drains
Flow Metering
Historical Review
Air Quality
Wetlands
Floodplains
Topography
Recreation
Geology
Soils Survey
Agriculture
Plants, Fish & Wildlife
Sensitive Features
Alma Sewer Ordinance
Sewer Rates
Cost Analyses
Alternative 5 - Regionalization
City of Alma
I.
SRF & SWQIF Draft Project Plan
Introduction
The City of Alma provides wastewater collection and treatment for the city and for portions of
Arcada and Pine River Townships. The city has completed a Sewer System Evaluation Survey
(SSES) of their sewer system in response to concerns over the age of the system and high flows
during wet weather.
The SSES has provided the following general conclusions regarding the sewer system:
Many portions of the city’s sewer system experience excessive infiltration; however, infiltration
is not considered cost-effective to remove.
Excess inflow is widespread throughout the collection system. Some inflow sources are costeffective to correct; however, capacity upgrades to some sections of sewer and pump stations will
be required even if inflow sources are corrected.
Portions of the city’s sewer system are 100 years old. About 36% of the sewer system is in need
of repair, lining, or replacement to address physical and structural defects or deterioration.
The city’s wastewater facilities should have adequate capacity to provide for anticipated growth.
The SSES has identified upgrades and repairs totaling more than $20 million. The city is planning to
complete the necessary upgrades and repairs in a phased approach. A phased approach will allow the
city to better manage the financial impact to the city and its customers. City staff will be better able
to manage several smaller projects over a period of several years than a single large project. Also, the
phased approach will allow subsequent work to be modified, if appropriate, based on the actual
results of I/I reduction from the initial phase(s).
As the initial phase, the city proposes to focus on the central business area and residential areas
adjacent and to the west. The SSES indicated that inflow is greatest in this area and footing drains are
a major source of inflow in this area. The city is seeking funding from the state’s low interest loan
programs for the initial phase of work. Since a portion of the work planned is footing drain
correction, funding through the Surface Water Quality Initiative Fund (SWQIF) is sought. The initial
work will also include upgrades to the public sewer system, so funding through the State Revolving
Loan Fund (SRF) is also planned.
This Project Plan provides basic information and details regarding the project planned by the city.
II. Study Area Characteristics
A. Service Area
The City of Alma provides for the collection and treatment of waste water for businesses,
institutions, and residences within their city limits and to portions of two abutting townships:
Arcada and Pine River. The service area is shown in Figure 1.
Page 1
City of Alma
SRF & SWQIF Draft Project Plan
B. Study Area
In addition to the areas which are now serviced by the city’s sanitary sewer system, extension of
sewers may support future development adjacent to the M-46 highway or to the US-127
interchanges. Extension of sewers to areas along the Pine River could protect and improve water
quality by replacing existing septic systems or support future development. For planning
purposes, the Study Area is assumed to include additional lands in Arcada and Pine River
Townships as shown in Figure 2.
Figure 2: Study Area
The City of St. Louis is located immediately northeast of the City of Alma and provides
wastewater service for the City of St. Louis and adjacent to portions of Pine River Township.
The City of St. Louis, City of Alma, and Pine River Township executed an urban utilities
agreement providing for the future extension of utilities into portions of Pine River Township.
The boundaries established by this agreement are reflected in the boundaries of the Study Area.
Page 3
City of Alma
SRF & SWQIF Draft Project Plan
Land use in the study area is mixed, primarily residential, commercial, institutional, and
industrial. Copies of the city’s zoning map and land use map are provided in Appendix 1. It is
anticipated that land use continues in similar fashion through the planning period.
Appendix 1 also includes a map showing the distribution of homes and businesses, and parks and
recreational areas.
The Pine River flows through the study area; it is used on a limited basis for recreational
activities. Public water supply is from wells and from the Pine River. A map showing the study
area surface waters and regional groundwater supplies is included in Appendix 2.
C. Economic Characteristics
Gratiot County is located in the center of Michigan’s Lower Peninsula between the industrial
areas of the south and the recreational area of the north. The county blends the rural and the
industrial sectors. Gratiot County is a leading producer of dry beans, sugar beets, corn wheat,
oats, poultry, pork, beef and dairy products. Agriculture accounts for more than 65% of all land
use. The commercial and industrial development in the county is centered primarily along the
US-127 corridor around the cities of Ithaca, Alma, and St. Louis. Manufactured products include
pleasure boats, molded plastic parts, aircraft, and auto parts. Three state correctional facilities
located in St. Louis provide additional significant stable employment. The county is also a
regional supplier of medical services and relies on the retail trade and service industries. The Pine
and Maple Rivers and three state game areas offer recreational opportunities in the county. Alma
College is located in the city of Alma. Table 1 below lists several of the major employers in the
immediate Alma area:
Table 1: Major Employers
Major Employer
Location
Product/Service
Alma College
Alma
Education
Alma Products
Alma
OEM mfg of automotive components
Gratiot Medical Center
Alma
Regional medical care
IAC (formerly LEAR)
Alma
Plastic products injection molded automotive parts
Masonic Pathways
Alma
Retirement community
Mich. Dept. of Corrections
St. Louis
3 state correctional facilities
Table 2 shows minority population and income data for Gratiot County and the Study Area.
Table 2: Minority Population and Income Data
Percent Minority
Percent Below
Poverty Level
Median Household
Income
Gratiot County
8.0%
10.3%
$36,163
City of Alma
6.3%
11.6%
$33,536
Pine River Twp.
4.0%
6.3%
$36,615
Arcada Twp.
3.9%
6.3%
$44,097
Community
Page 4
City of Alma
SRF & SWQIF Draft Project Plan
Only a small portion of Pine River Township and Arcada Township are included in the Study
Area. The data shown in Table 2 shows data for the townships as a whole, but should provide
some indication of conditions in the Study Area.
D. Growth
The city’s population has been relatively stable over recent years, with minimal growth. Some of
this stability results from the large institutions located in the city, such as Alma College, Gratiot
Medical Center, and Masonic Pathways.
Sewers are available throughout the city and in the adjacent townships in the developed areas
adjacent to the city. With the recent difficult economic times and the closing of the Total
Refinery several years ago, there are vacant properties currently available within the sewered
areas. These properties can support increased economic activity without significant need for new
wastewater facilities. However, wastewater needs vary significantly depending upon the type of
industry and specific site requirements, so there is certainly potential for increased wastewater
service.
There are two interchanges from the US-127 freeway which serve Alma and the adjacent area.
As economic conditions improve, continued development around either of these interchanges can
result in the need for additional sewers and increased wastewater service.
City and county officials are working diligently to attract new businesses to the area. As these
efforts succeed, it is likely that new workers will relocate to the area, including the city and
township areas served by sewers.
For this study, it is assumed that growth within the townships and city will grow at an annual rate
of 0.5 percent. Over the twenty year study period, it is assumed that the population of the city
and townships will increase by 10%.
E. Existing Facilities
1. General
A map showing the existing wastewater facilities is included in Appendix 3. The map shows
the layout of the collection system, locations of pumping stations, and the WWTP.
2. Wastewater Treatment Plant
The Alma Wastewater Treatment Plant is an Activated Sludge Plant designed to provide
treatment for 2.5 million gallons per day. The average daily flow rate for 2009 was about 2.58
million gallons per day.
Sewers convey wastewater to the WWTP headworks. A self-cleaning bar screen at the
headworks provides screening of raw wastewater. Two raw sewage pumps with a capacity of
6,000 gpm each convey the screen wastewater to the aeration tanks for secondary treatment.
The raw sewage pumps were installed in 1974 and in good working condition.
The aeration tanks were constructed in 2005; of the eight tanks only three are regularly used
for secondary treatment. Aeration to the tanks is provided by three blowers. The blowers
were installed in 1974, 1992, and 2009 are in good condition. Air is distributed within the
three tanks through fine-bubble diffusers across the bottoms of the tanks.
Page 5
City of Alma
SRF & SWQIF Draft Project Plan
Effluent from the aeration tanks is settled in one of the two circular clarifiers. Each clarifier
is 55 feet in diameter. One was installed in 1959 and one was installed in 1974. Both are in
good condition.
Phosphorus reduction is achieved by chemical treatment. Ferric chloride is added prior to
clarification. The ferric chloride combines with the dissolved phosphorus to form a
precipitate which settles out in the clarifier.
Settled sludge from the clarifiers is returned to the aeration tanks by the return activated
sludge (RAS) pumps. There are three RAS pumps, each installed in 1974 and all are in good
working condition.
Secondary effluent for the clarifiers is disinfected with gas chlorine. The chlorine feed
equipment is in fair condition. The city has evaluated options for disinfection because of
safety concerns with chlorine gas and because of the need to replace the equipment soon.
The city plans to switch to liquid sodium hypochlorite solution as a disinfectant and replace
the gas injection system with a liquid feed pump system.
Following disinfection, treated effluent flows into a polishing pond where the chlorine
residual diminishes and remaining particles settle out before discharging to the Pine River.
Excess biological solids from the treatment process are pumped into two of the unused
aeration tanks and are stabilized by aerobic digestion.
Redundant and/or duplicate equipment and processes provide reliability. Dual power feeds
supply electricity to the WWTP. A backup generator is also available to operate the WWTP
in the event of power failure.
The city plans for the replacement of some pumps, blowers, clarifier drives, and disinfection
equipment over upcoming years funded through equipment replacement funds provided in the
city’s budgets.
3. NPDES Permit
The city has been issued NPDES permit MI0020265 for discharge of treated wastewater to
the Pine River. The permit establishes effluent limitations, monitoring requirements, and
other provisions. A copy of the permit is included in Appendix 4. The permit expires on
October 1, 2013.
4. Biosolids
Biosolids resulting from treatment of wastewater are aerobically stabilized and then applied
as nutrients to agricultural land. An average of 250 dry tons of biosolids is generated
annually. Biosolids are concentrated and stored at the WWTP until they can be applied to
farmland, typically two or three times a year. The city uses a contractor to haul and dispose
of stabilized biosolids.
Handling and disposal of the city’s biosolids is consistent with the Program for Effective
Residuals Management (PERM), which was approved by the Michigan Department of
Natural Resources and Environment (MDNRE) in 2000. The city reports to the MDNRE
annually regarding the quantity and characteristics of biosolids from the WWTP.
Page 6
City of Alma
SRF & SWQIF Draft Project Plan
5. Collection System
The city’s wastewater collection system consists of the following:
48.11 miles of gravity sewer
1.46 miles of force main
14 pumping stations
Appendix 3 provides maps showing the details of the collection system. Table 3 shows the
pumping capacities of each pump station.
Table 3: Pump Station Characteristics
Pumping Rate
Pump 1
Pump 2
Both
(gpm)
(gpm)
(gpm)
2
385
385
500
385
Year
Constructed
1977
3
175
175
250
175
1960
4
320
320
420
320
1977
5
210
210
300
210
1960
7
160
160
220
160
1960
8
520
410
700
520
1960
9
140
140
200
140
1977
10
140
140
200
140
1977
11
150
150
175
150
1977
12
325
325
450
325
1977
13
180
180
270
180
After 2000
Pump Station
Firm Capacity
(gpm)
14
After 2000
15
After 2000
The city has two portable generators which are available to operate any of the pumping
stations in the event of power failure. Each pumping station is provided with automatic
controls and an alarm notification system.
6. Infiltration and Inflow
Following is a general overview of the conclusions of the completed SSES, relative to I/I.
Many portions of the city’s sewer system experience excessive infiltration; however,
infiltration is not considered cost-effective to remove
Excess inflow is widespread through the collection system. Some inflow sources are
cost-effective to correct; however, capacity upgrades to some sections of sewer and pump
stations will be required too.
Details regarding I/I and the collection system are included in the SSES.
7. Wastewater Characteristics
Total wastewater flows are measured at the city’s WWTP. Figure 3 shows a graph of the
recorded flows for 2009.
Page 7
City of Alma
SRF & SWQIF Draft Project Plan
Figure 3: 2009 Recorded Daily Flows
Daily WWTP Flow (millions of
gallons)
12
10
8
6
Daily WWTP Flow
(millions of gallons)
4
2
12/1/09
11/1/09
10/1/09
9/1/09
8/1/09
7/1/09
6/1/09
5/1/09
4/1/09
3/1/09
2/1/09
1/1/09
0
Table 4 provides a summary of wastewater influent flows and characteristics received at the
WWTP.
Table 4: Summary of WWTP Flows and Characteristics (2009)
Total Annual WWTP Volume
943.49
MG
2.58
mgd
10.24
mgd
Biochemical Oxygen Demand
90.3
mg/l
Biochemical Oxygen Demand
1944
LBS
Total Suspended Solids
93.3
mg/l
Total Suspended Solids
2009
LBS
Total Phosphorus
2.71
mg/l
Total Phosphorus
58
LBS
Ammonia Nitrogen as N, (NH3-N)
14.54
mg/l
Ammonia Nitrogen as N, (NH3-N)
313
LBS
Average Daily Flow
Peak Day Flow
8. Septage Receiving Facilities
The Alma WWTP does not receive septage waste, other than portable toilet waste. The
facility receives 1,000 to 6,000 gallons of portable toilet waste per month.
The city has an approved Septage Waste Receiving Facility Operating Plan which provides
for receiving portable toilet waste. Waste from portable toilets is received in such small
quantities and intermittently and has no noticeable impact on WWTP operations or
performance.
Page 8
City of Alma
SRF & SWQIF Draft Project Plan
9. Major Dischargers
Following are major discharges to the city’s wastewater system.
Alma Products Company – 2000 Michigan Avenue - Manufacturer and re-manufacturer
of automotive related parts
Alma College (614 W. Superior) – Education
Gratiot Medical Facility (300 E. Warwick) - General Hospital Services
Masonic Pathways (1200 Wright Avenue) - Senior Living Facility
10. Industrial Pretreatment Program
The city does not presently have an established Industrial Pretreatment Program (IPP).
Wastewater from one industrial discharger of contact cooling water is presently being
reviewed by city staff and MDNRE staff to evaluate the need for an IPP or other measures.
11. Dry and Wet Weather Flows
The SSES included an analysis of wastewater flows. Table 5 is a summary of the base
wastewater flow and I/I.
Table 5: Inflow and Infiltration
Annual Volume
(millions of gallons)
Daily Average
(millions of gallons)
943.49
2.58
Base Domestic Wastewater Flow for 2009
372.86
1.02
39.5%
Excess Flow (I&I)
570.63
1.56
60.5%
Infiltration
428.60
1.17
45.4%
Inflow
142.03
0.39
15.1%
Characterization of WWTP Flow
Total Wastewater Flow for 2009
% of
Total
III. Summary of Studies, Inspections, and Analyses
A. Sewer System Study
In 2005, ROWE Professional Services Company completed a study of the city’s sewer system to
provide an understanding of its ability to meet current and future needs. The study concluded that
the city’s sanitary sewer collection system was susceptible to inflow and infiltration and although
the amount of infiltration is significant, the peak flows following rainfall events have a more
critical impact on the sewer system’s capacity. It indicated that reducing excess flow resulting
from rain events would benefit the city by relieving capacity issues and reducing pumping and
treatment expenses.
Subsequent to the 2005 Study, the city has completed the following to better understand the
condition of the sewer system.
•
•
•
•
•
•
Smoke Testing of Collection System in 2005, 2008 & 2009
Sanitary Sewer Flowmeter Monitoring in 2009
Analysis of results from Smoke Testing and Flow Monitoring
Home and Business Inspections 2009
Field Review/Manhole Inspections 2005/2009
Collection System inspection videotaping 2007-2009
Page 9
City of Alma
SRF & SWQIF Draft Project Plan
B. Smoke Testing
Smoke testing of the Alma sanitary sewer system was conducted in 2005, 2008, 2009, and 2010.
Smoke testing was used to identify locations of cross connections and inflow sources. 73
potential sources of inflow were identified by smoke testing. About half of these have been
corrected by the city since their discovery. There are 36 potential inflow sources which remain to
be corrected. Table 6 shows the remaining potential sources of inflow.
Table 6: Potential Sources of Inflow from Smoke Testing
Potential Inflow Sources
Quantity
Catch Basins
8
Downspouts/Roof Drains
3
Cleanouts
8
Pipe Leaks
9
Manholes
8
C. Field Review/Manhole Inspections
Eighteen percent of the sanitary sewer manhole structures were inspected during field work in
2005 and 2009. About half of the manholes inspected indicated the need for some repair or
rehabilitation. Table 7 shows the work needed based on these inspections.
Table 7: Summary of Manhole Inspections
Manholes Inspected
Recommended Repair
Quantity
%
175
System Wide
(Projected)
950
Total Reconstruction
10
5.7%
54
Chimney Reconstruction
42
24.0%
228
Lining
35
20.0%
190
The field review did not identify significant potential for cross connections between storm sewer
and sanitary sewer. However, the sanitary sewer that flows in a southeasterly direction alongside
a county drain storm sewer between Superior Street and Mechanic Street is suspected to be a
probable cross connection source. The storm sewer and sanitary sewer cross each other multiple
times in this stretch. On several occasions the sanitary sewer pipe actually flows through the
storm sewer structures. Smoke testing identified one confirmed cross connection between the two
systems.
D. Collection System Video Taping
Ten percent of the City of Alma’s sanitary sewer system has been videotaped. As part of this
study, information from inspections in 2007, 2008 and 2009 has been reviewed. The video tapes
identify the location, size and type of pipe material, length between pipe joints, locations of sewer
leads, approximate pipe flow depths and any abnormalities. The vast majority of the collection
system pipe material is vitrified clay pipe, with joints at every three feet. Some of the noted
problems included blockages, low points, infiltration through cracks in pipes and failed joints,
root intrusion through cracks and joints, and mineral deposits (often caused by seepage into the
pipe). All of the above identified deficiencies can be problematic in the best of conditions. With
Page 10
City of Alma
SRF & SWQIF Draft Project Plan
areas of high groundwater table (as common in Alma) each of these locations is a source of
infiltration.
E. Home & Business Inspections
During the summer/fall of 2009, building inspections were conducted in the two focus areas. Area
1 is the residential area in the vicinity around Lift Station #8. Area 2 is made up mostly of the
downtown business district located along Superior Street, with some residences located both
north and south of Superior Street. All property owners in the two areas were sent a letter
requesting access to their property to conduct an inspection. The main purpose of the inspections
was to better quantify the number of homes and businesses connected to the sanitary sewer by
sump pumps, floor drains, footing drains or downspouts. A map showing these areas is included
in Appendix 5.
Of the 504 properties in the focus areas, a total of 127 parcels were inspected, which is
approximately 25% of the total. The inspections showed that around 40% of the
homes/businesses had at least one illicit connection to the sanitary sewer.
Floor drains and footing drains can be directly connected to the sanitary sewer or by a sump
pump. Sump pump flow rates can vary widely; flows ranging from 5 to nearly 100 gallons per
minute are common. A substantial amount of inflow can result from footing drains and sump
pumps, especially in high groundwater areas. During a significant rain event, stormwater from the
roof or near the foundation can percolate into the ground to the footing drains. Downspouts are
also a source of inflow.
Some sump pumps in Area 1 were identified during the inspections to run almost constantly.
Other homes have basements in high groundwater locations, with no sump pump, floor elevations
lower than the available storm sewer, which likely have footing drains directly connected to the
sanitary sewer.
The results from the building inspections in the two focus areas have been used to make
projections regarding building connections in other areas.
F. Flow Metering and Analyses
Flow metering at key locations in the city’s sewer system was conducted between May and
December 2009. A map showing the meter locations and the area tributary to each is included in
Appendix 6.
During the metering period, rainfall was measured at the WWTP.
Sewer flow records were analyzed to determine the flow during and following wet weather and
during periods without rain.
Table 8 shows the average flow at each meter point and from each meter district. Infiltration is
considered excessive if the average exceeds the rate of 120 gallons per day per person. Table 8
also shows that infiltration is excessive in seven of the meter districts.
Page 11
City of Alma
SRF & SWQIF Draft Project Plan
Table 8: Dry Weather Flow Analysis
Average
(gpm)
Incremental
Average
(gpm)
Incremental
Population
Average Flow
per Person
(gpcd)
Exceeds120 gpcd?
1
72
14
383
53
no
2
49
37
55
969
yes
3
58
58
277
302
yes
4
12
12
268
65
no
100
576
34
1,914
26
no
300
120
120
772
224
yes
400
32
32
796
58
no
500
313
76
1,568
70
no
800
155
34
775
63
no
900
77
77
951
117
no
1000
82
37
701
76
no
1100
11
11
51
308
yes
1200
34
34
251
195
yes
200
164
164
955
247
yes
600
41
41
698
85
no
700
82
0
44
0
no
1400
74
74
827
129
yes
1500
8
8
384
30
no
Meter
Wastewater facilities should have sufficient capacity to handle peak flows resulting from a
weather event equal to the 25 year, 24 hour storm. For Alma, this is 3.9 inches of rain in 24 hours
with a peak hour rainfall of 1.45 inches.
During the metering period, rainfall ranged from 0.05 inches to 1.47 inches over 24 hours. Sewer
flows were analyzed to determine the increase in flows resulting from a rain event. A statistical
analysis was completed to extrapolate the increase in sewer flow which is expected from a 25
year, 24 hour storm. Table 9 shows the rain-induced (RI) flow anticipated at each meter point.
The table combines the RI flow with the peak wastewater flow that would normally be expected
to determine the 25 year peak flow.
Page 12
City of Alma
SRF & SWQIF Draft Project Plan
Table 9: Analysis of 25 Year, 24 Hour Peak Flow
Dry Weather
25Year
Average
(gpm)
Peak
(gpm)
RI Flow
(gpm)
Peak
(gpm)
1
72
79
704
783
2
49
92
374
466
3
58
110
250
360
4
12
100
167
267
100
576
1,027
1,985
3,012
500
313
828
1,912
2,740
800
155
543
1,842
2,385
900
77
249
1,426
1,675
1000
82
163
1,071
1,234
1100
11
46
176
222
1200
34
108
419
527
200
164
299
259
558
300
120
277
186
463
400
32
106
60
166
600
41
89
285
374
700
82
250
2,093
2,344
1400
74
157
2,015
2,172
1500
8
48
168
216
Meter
Sewers and pump stations need to provide sufficient capacity for the 25 Year peak flows shown
in Table 9, or backups or overflows are likely. Figure 4 shows sections of the sewer system and
pumping stations that do not have adequate capacity for the 25 year peak flows.
Page 13
City of Alma
SRF & SWQIF Draft Project Plan
G. Need for Project
1. Compliance Status
Discharge from the city’s WWTP consistently meets the limits established in the NPDES
permit. Table 10 shows limits established by the city’s NPDES permit and provides extreme
samples over the summer months of 2009. Limits are strictest in the summer.
Table 10: WWTP Effluent
Monthly
Limit
(lbs)
7 Day
Limit
(lbs)
Maximum
Monthly Quantity
(lbs)
Maximum
Daily Quantity
(lbs)
CBOD
150
210
53
108
Suspended Solids
420
630
53
135
63
13
24
8
17
Parameter
Ammonia Nitrogen
Phosphorus
21
Parameter
Monthly
Limit
(mg/l)
7 Day
Limit
(mg/l)
Maximum
Monthly Quality
(mg/l)
Maximum
Daily Quality
(mg/l)
CBOD
7
10
3.0
8.0
Suspended Solids
20
5.0
7.0
0.7
1.2
1
0.8
1.0
200
45.0
280.0
Ammonia Nitrogen
Phosphorus
Fecal Coliform Bacteria
3
2. Orders
There are no enforcement actions against the city.
3. Water Quality Problems
Public sewers are available throughout the City of Alma and in developed areas of two
adjacent townships. Areas beyond the city’s sewer service area are rural and much of the
land is used agriculturally. Soils outside of the service area are heavy and not well suited for
onsite septic systems; however, homes and businesses are scattered so the existing septic
systems do not result in a significant threat to water quality.
New sewer service to areas without sewers is not presently being contemplated by the city or
either Pine River or Arcada Townships. However, the city has agreements to provide sewer
service to areas outside of the city when development or needs arise.
H. Projected Needs for the Next 20 Years
The population of Alma and adjacent areas has been fairly stable. Long-established institutions
such as Alma College, the Masonic Home, and the Central Michigan Medical Center contribute
to the area’s stability. Although some large manufacturing and industrial facilities have closed,
many remain and community officials continue strong efforts to re-develop former sites.
Future growth is difficult to project. For this study, it is assumed that growth within the city’s
sewer district will occur at a rate of ten percent over the next twenty years.
Page 15
City of Alma
I.
SRF & SWQIF Draft Project Plan
Future Environment without the Proposed Project
The city plans to upgrade its sewer system to remove footing drains, catch basins, and roof drains
that are connected to the city’s sanitary sewer system. The city also plans to upgrade sections of
sewer and pumping stations which do have sufficient capacity for wet weather flows.
Without the upgrades planned by the city, wet weather flows are expected to continue to increase
and the current capacity limits will become more critical. Without the upgrades planned by the
city, there will be increasing potential for basement backups and/or sanitary sewer overflows.
High flows from wet weather can reduce the WWTP’s ability to effectively treat wastewater
which can result in permitted discharge limits being exceeded.
Completing the proposed project will better enable the city to meet the needs of its customers and
reduce the potential for environmental impact.
J. Population Data
Table 11 summarizes the current population and future growth assumed for planning purposes.
Table 11: Population Summary
Base Wastewater Flow
Population
Existing
(gpd/person)
Residential
Equivalent Units
(REU)
(gpd)
9,275
110
1,020,250
4,883
928
70
64,925
488
10% Increase
5 Year
9,507
1,036,481
5,005
10 Year
9,739
1,052,713
5,127
20 Year
10,203
1,085,175
5,371
K. Environmental Setting
1. Cultural Resources
There will be a search for historical and/or archaeological sites that can be indentified that
would be affected by this project. An application for Section 106 Review has been submitted
to the State Historic Preservation Office (SHPO). Copies of the correspondence to SHPO are
included in Appendix 7. Any historical or archaeological site identified by this search will be
listed and a determination will need to be made if the proposed work plan/construction
activities will adversely affect any identified locations.
There are four sites in the city which are listed on the State Historical Register. The four sites
are identified in Appendix 7.
In addition to the four sites listed on the State Historical Register, the city’s downtown area is
listed on the State Historical Register as a Historic District.
2. The Natural Environment
a) Climate
Construction scheduling and activities resulting from this work plan will be impacted by
climate. Michigan state law incorporates frost laws or seasonal weight restrictions to
preserve and protect the road systems during the thawing and refreezing period of
Page 16
City of Alma
SRF & SWQIF Draft Project Plan
springtime weather. State law provides the months of March, April and May are
automatically reduced loading months. The county road commissions may extend these
periods based on weather conditions.
Placement of concrete and bituminous mixtures will be impacted by air temperature, and
thus construction of these items may be limited or not allowable during winter months.
b) Air Quality
A copy of the MDEQ Air Emissions Reporting System Annual Pollutant Totals for Alma,
MI is attached in Appendix 8.
The project will have minimal adverse temporary impacts on the air quality near the
project area. Construction activities will occasionally require the use of heavy
construction equipment which may generate additional short term emissions to the
project area. The primary adverse impact may be dust generated from the construction
activities. Best management practices including applications of dust palliatives and water
on disturbed areas during dry periods will be implemented throughout the duration of the
project to control dust.
c) Wetlands
A copy of the MDEQ Wetlands Inventory Map of Alma, MI is attached in Appendix 9.
Per the MDEQ map, wetland areas within the city limits are located primarily near the
Pine River. The map indicates that there are no state regulated wetlands present in the
project area.
d) Coastal Zones
There are no coastal zones within the project area.
e) Floodplains
A Federal Emergency Management Agency (FEMA) floodplain map of Alma, MI is
attached in Appendix 10. Potentially, portions of the proposed project work will occur
within the 100 year floodplain of the Pine River (refer to Map of Sensitive Areas Appendix 17). The project construction within the floodplain will require a permit under
the Floodplain Regulatory Authority of Part 31, Water Resources, of the NREPA.
Following construction, areas within a floodplain which have been disturbed will be
restored to their existing surface contours. The project will have no permanent impact to
the floodplains.
f) Natural or Wild and Scenic Rivers
The Pine River is the only river located within the City of Alma. The Pine River in Alma
is not designated as a wild and scenic river on the National Wild and Scenic Rivers
System.
g) Major Surface Waters
Major surface waters are depicted on the USGS map provided in Appendix 11.
h) Recreational Facilities
A map of the City of Alma parks and outdoor recreation facilities is included in
Appendix 12. The proposed construction activities will not impact the city’s parks and
recreational facilities.
Page 17
City of Alma
SRF & SWQIF Draft Project Plan
i)
Topography
Existing topography can be seen on the USGS map provided in Appendix 11.
j)
Geology
The geographic and topographic features of the Lower Peninsula of Michigan were
shaped by glacial and melt water action. The continental glacial movements during
Pleistocene time broke down soil and rocks and re-deposited the materials as sediments.
Lower Michigan is covered by glacial sediments or gravels, sand and clays derived from
them. The bedrock of the entire Lower Peninsula is made up of Paleozoic and Mesozoic
sedimentary rocks of Cambrian to Jurassic age. This large regional geological structure
is known as the Michigan basin. MDNR maps of the 1982 Quaternary Geology of
Michigan and 1987 Bedrock of Michigan are attached for reference in Appendix 13. The
geological structure and formations within the study area will not affect the choice of
alternatives on the project.
k) Soils
The predominant soil in the project area is loamy sand. A United States Department of
Agriculture (USDA) Web Soil Survey Map is included in Appendix 14 showing the soils
present in the project area.
Based on discussions with the Gratiot County Environmental Health Supervisor, a
registered sanitarian, the soil structure and water table in the entire Gratiot County area
are generally of poor suitability for on-site sewage disposal. Development potential in
areas of the county where public sewer service is not available is limited for this reason.
l)
Agricultural Resources
A USDA Web Farmland Classification Map is included in Appendix 15 showing the soil
farmland ratings in the project area. Based on the soil survey, the farmland
classifications in the project area vary from not prime farmland to prime farmland if
drained. No farming areas currently exist within the project area. The project area
consists of developed residential and commercial zones within the city.
m) Fauna and Flora
A search was made of the County Distribution of Michigan’s Federally Threatened,
Endangered, Proposed and Candidate Species created by the U.S. Fish and Wildlife
Service. A copy of the findings for Gratiot County is attached in Appendix 16. The
endangered Indiana Bat was found to reside in Gratiot County. The bat habitat includes
river corridors with well developed woods in the summer, caves and mines in the winter.
Based on the described habitat, it appears the project will not have any impact on bat
habitat. The project area encompasses urban development with little to no wooded areas
within close proximity to the river.
A search was also made on the Michigan Department of Natural Resources Web
Endangered Species Assessment. The resulting map indicated no listed features in the
study area. A copy of the map is provided in Appendix 16.
n) Unique Features
There are no unique features in the study area that will be affected by the proposed
project.
Page 18
City of Alma
SRF & SWQIF Draft Project Plan
IV. Development of Alternatives
Investigation and analyses have indicated that the city’s wastewater facilities have the following
needs:
Sewer system is susceptible to excessive I/I, resulting in inadequate capacity for significant wet
weather conditions
The sewer system is aging, and about 36% of the sewer system is estimated to require repair,
replacement, or rehabilitation to provide continued, long-term reliable service.
These needs are projected to cost more than $20 million. To better manage the execution of the
needed work and to minimize the financial impact to the city’s wastewater customers, the city plans
to complete the proposed work in phases. The city plans to complete the highest priorities first.
Capacity issues resulting from excess inflow have been greatest in the central business area and
adjacent areas. The SSES also concluded that inflow is a significant problem and that it can be costeffective to remove some sources of inflow. For the initial phase of work, the city plans to focus on
alternatives for correcting excess inflow sources and/or providing additional capacity to accommodate
wet weather flows.
Alternatives considered will exclude the southeast part of the city. Additional investigation and
analysis is planned in this area before a thorough evaluation of alternatives for addressing inflow in
this area can be completed.
City staff has addressed about half of the isolated inflow sources scattered across the city, such as
directly connected catch basins, leaky manhole covers, open cleanouts, and directly connected
downspouts. City staff plans to continue working to address the remaining isolated sources of inflow
so these are excluded from the alternatives considered.
The following alternatives have been identified to address wet weather issues with the city’s sewer
system.
Alternative 1 – Provide Upgrades to Transport and Treat I/I
Alternative 2 – Correct Some Footing Drains and Increase Collection System Capacity
Alternative 3 – Do Nothing
Alternative 4 – Optimum Utilization
Alternative 5 – Regionalization
V. Analysis of Alternatives
A. Alternative 1- Provide Upgrades to Transport and Treat I/I
This alternative provides for upgrades to the city’s wastewater facilities to provide sufficient
capacity for the wastewater flows expected from a 25 year, 24 hour storm event. This alternative
does not provide for any removal of I/I.
Section III.F identified deficiencies in the existing collection and treatment facilities to provide
sufficient capacity for peak flows resulting from the 25 year, 24 hour storm. Figure 5 shows the
upgrades planned to upgrade the sections which have been identified as inadequate.
Table 12 provides the estimated project cost for Alternative 1.
Page 19
City of Alma
SRF & SWQIF Draft Project Plan
Table 12: Alternative 1
Pipe Size
(inches)
Quantity
Unit Cost
Total
Collection System Upgrades
Sewer Replacement
Park Avenue
North of Mechanic
24
275
$340
$93,500
Mechanic Street
Grant to Prospect
24
1,300
$340
$442,000
Mechanic Street
Maple to Grant
15
500
$219
$109,500
Mechanic Street
Philadelphia to Maple
10
800
$170
$136,000
Philadelphia Street
North of Mechanic
12
300
$194
$58,200
West of State Street
South of Center
24
650
$340
$221,000
West of Prospect Avenue
South of Superior
24
650
$340
$221,000
Superior Street
Philadelphia to Alger
10
1,400
$170
$238,000
Park Avenue
Downie to Superior
18
500
$243
$121,500
Downie Street
Wright to Park
18
500
$243
$121,500
Falkirk
To Alma College
12
400
$194
$77,600
12
1,300
$194
$252,200
Alma College
Hastings Street
Woodworth to Gratiot
18
450
$243
$109,350
Court Avenue
Walnut to Liberty
10
350
$170
$59,500
Pump Stations
Pump Station 7
1
$100,000
$100,000
Pump Station 8
1
$100,000
$100,000
Raw Sewage Pumping
1
$250,000
$250,000
Clarification
2
$1,000,000
$2,000,000
WWTP Upgrades
Summary
Subtotal - Estimated Construction Cost
$4,710,850
Contingencies
30%
$1,413,255
Engineering, Legal, Administration
20%
$942,170
Project Budget
$7,066,275
The present worth of Alternative 1 is $8,985,049. The present worth is computed in Appendix
20.
Page 20
City of Alma
SRF & SWQIF Draft Project Plan
B. Alternative 2 - Correct Some Footing Drains and Increase Collection System Capacity
Although the SSES concluded that disconnecting footing drains across the city or randomly were
not cost-effective, the SSES concluded that footing drain disconnection in the central business
area and adjacent residential areas is cost-effective. Within this area, there are a large number of
homes and businesses with connected footing drains and several sewer mains which are
inadequate for the 25 year, 24 hour storm. Correction of footing drains in this area reduces the
need for sewer upgrades in this area which combine to reduce overall cost. It is assumed that
cost-effective inflow sources which have been identified will be corrected by city staff.
Figure 6 shows the proposed upgrades included in Alternative 2. Table 13 provides the estimated
project cost for Alternative 2.
Table 13: Alternative 2
Footing Drain Disconnect
Footing Drain Disconnect
4" Storm Drain
Collection System Upgrades
Sewer Replacement
Prospect Avenue
North of Mechanic
Mechanic
Grant to Prospect
Mechanic Street
Maple to Grant
Mechanic Street
Philadelphia to Cedar
West of State Street
South of Center
Park Avenue
Downie to Superior
Downie Street
Wright to Park
Falkirk
To Alma College
Alma College
Hastings Street
Woodworth to Gratiot
Court Avenue
Walnut to Liberty
Pump Stations
Pump Station 7
Pump Station 8
WWTP Upgrades
Raw Sewage Pumping
Clarification
Summary
Subtotal - Estimated Construction Cost
Contingencies
Engineering, Legal, Administration
Project Budget
Pipe Size
(inches)
Quantity
4
260
15,000
$5,000
$35
$1,300,000
$525,000
18
18
15
10
24
18
18
12
12
18
10
275
1,300
500
400
650
500
500
400
1,300
450
350
$243
$243
$219
$170
$340
$243
$243
$194
$194
$243
$170
$66,825
$315,900
$109,500
$68,000
$221,000
$121,500
$121,500
$77,600
$252,200
$109,350
$59,500
1
1
$50,000
$50,000
$50,000
$50,000
0
0
$60,000
$1,000,000
$0
$0
30%
20%
$3,447,875
$1,034,363
$689,575
$5,171,813
Unit Cost
Total
The present worth of the Alternative 2 is $6,575,494. The present worth of Alternative 2 is
computed in Appendix 20.
Page 22
City of Alma
SRF & SWQIF Draft Project Plan
C. Alternative 3 – Do Nothing
If nothing is done, it is likely that wet weather flows will continue to increase as the city’s sewer
system ages and deterioration continues. The system will not be able to provide sufficient
capacity for peak flows from a 25 year, 24 hour storm event and the potential for backups, SSOs,
and exceeding NPDES permitted limits will increase.
Over the last few years, the city has worked to study and better understand the needs of their
wastewater facilities. The city understands that there are many needs to be addressed and are
committed to working to provide the upgrades, repairs, and maintenance so that the wastewater
system will continue to provide reliable service for city customers for years to come.
The “Do Nothing” alternative is not a feasible or acceptable alternative, and will not be
considered further.
D. Alternative 4 – Optimum Utilization
This alternative explores the potential for optimization of the operation of existing facilities.
The primary issues identified with the city’s wastewater facilities are 1) excess inflow and
resulting capacity problems, and 2) needed repairs and rehabilitation resulting from the system’s
age. Improved efficiencies, different operating strategies, and other methods for optimization
will have little benefit in addressing the issues identified.
E. Alternative 5 - Regionalization
The City of St. Louis is located four miles northeast of Alma. St. Louis operates a wastewater
treatment plant and sewer system which provides service to residences, businesses, industries,
and institutions in the City of St. Louis as well as portions of Pine River Township and Bethany
Township adjacent to the city.
Wastewater flow to the St. Louis WWTP averages about 1.3 mgd. The St. Louis sewer system is
susceptible to increased flows during wet weather.
If a regional system is constructed, either the Alma or St. Louis WWTP will require upgrades to
provide treatment for both areas. Additionally, a new pipeline will need to be constructed to
convey wastewater from one community to the other for treatment. A conceptual design and
estimate for this alternative are provided in Appendix 21. The cost for this alternative is greater
than other alternatives and implementation will be more difficult. The project will have a greater
impact on environmental features and will require the coordination and cooperation of three local
governmental units. It will also encourage sprawl by making sewers more accessible between
Alma and St. Louis. This alternative will not be considered further at this time.
F. Analysis of Principal Alternatives
Of the alternatives presented, Alternative 2 has the least cost when considering both the project
cost and the present value.
Alternatives 1 and 2 were considered feasible alternatives. Neither of these alternatives will have
a significant negative impact on the environment; completion of any of the alternatives will
reduce the potential for long-term environmental impacts. Work planned by any of the projects is
confined to replacing or rehabilitating portions of the existing sewer system; areas outside of the
existing service areas will not be impacted.
Page 24
City of Alma
SRF & SWQIF Draft Project Plan
All of the work planned for Alternative 1 is located in the public right-of-way. Much of the work
planned by Alternative 2 is in the public right-of-way, but a significant portion of the planned
work will require that private property owners allow the work of disconnecting footing drains
from privately owned buildings. This has been presented to citizens at public meetings and
through newsletters and it is believed that most property owners within the focus areas are willing
participate.
The city has informed citizens of its plans to make improvements to the sewer system, through
special meetings and reports at council meetings and other meetings.
Nothing has been identified that should result in any of the alternatives being unimplementable.
VI. Technical and Other Considerations
A. Infiltration and Inflow
I/I is excessive and has been one of the primary forces driving the city’s plans for upgrading their
sewer system. An SSES has been completed to quantify and identify I/I. The SSES also
developed alternatives for addressing excess I/I, some of which have been considered in this
Project Plan.
B. Sludge and Residuals
None of the alternatives considered propose changes to processes at the city’s WWTP. Any work
contemplated at the WWTP is proposed to provide hydraulic capacity only. Sludge volumes or
its characteristics are not expected to be affected by the alternatives considered as feasible.
C. Industrial Pretreatment
None of the alternatives considered propose changes to processes at the city’s WWTP. Any work
contemplated at the WWTP is proposed to provide hydraulic capacity only. The city does not
presently receive industrial wastewater so there is no concern regarding the impact of industrial
wastewater on WWTP residuals, treatment process upsets, or direct discharge through SSO’s.
D. Growth Capacity
The population of the Alma area has been fairly stable and future growth is estimated at ten
percent over the next twenty years. There is ample capacity in the city’s sewer system and
WWTP for growth provided that inflow can be reduced to the levels proposed by the alternatives
which have been developed.
E. Areas without Sewers
Sewer service is available throughout the city. The city also provides sewer service to developed
areas of Pine River Township and Arcada Township, adjacent to the city.
Extension of sewer service to “new” areas is not planned with any of the alternatives being
considered. The city has agreements with both townships for extending sewers to other areas
within the townships, as the respective townships determine that they are needed.
F. Reliability
The city’s WWTP, pumping stations, and sewer system meet normal standards for reliability
other than problems which can result from inadequate capacity during wet weather and some
concerns regarding the age and condition of the sewers. Alternatives 1 and 2 have been
developed to provide sufficient capacity for wet weather conditions. Although there are sections
Page 25
City of Alma
SRF & SWQIF Draft Project Plan
of sewers which will require replacement, repair, or rehabilitation; none have been identified
which are an immediate concern regarding the system’s reliability. The city plans to develop a
program for evaluating, prioritizing, and planning for the rehabilitation of their existing sewer
system.
G. Alternative Sites and Routings
The alternatives developed address correcting existing issues in the existing sewer system.
Because of the nature of the planned work, alternative routes will not be feasible.
H. Combined Sewer Overflows
The city does not have a combined sewer system. There are no known physical overflow outfalls
from the sanitary system.
The city has not experienced sanitary sewer overflows (SSOs). However, during wet weather
there have been instances where the sewer system has surcharged. The alternatives developed
have been designed to provide sufficient capacity in the collection system for a 25-year, 24-hour
storm. This will reduce the potential for future SSOs.
I.
Contamination at the Project Site
Physical examination and a search of records regarding the areas where work is contemplated by
Alternatives 1 and 2 do not indicate the presence of contamination from sources such as
petroleum contamination of soil, discarded hazardous materials, contaminated runoff, or
hazardous building materials.
VII. Selected Alternative
Alternative 2 has the least cost (both project cost and present value). No issues have been identified
with the two feasible alternatives (Alternatives 1 and 2) which appears to result in either not being
implementable or resulting in either of them being less challenging than the other. Alternative 2 is
the selected alternative.
The proposed project is shown on Figure 6.
A. Relevant Design Parameters
Alternative 2 has been developed to address capacity problems resulting from wet weather flows.
The alternative addresses capacity problems through reducing inflow and adding capacity.
Inflow will be reduced by correcting directly connected footing drains in two areas of the city.
Two pump stations and several sections of the sewers are planned to be upgraded to provide more
capacity.
Table 14 summarizes the proposed design criteria.
Page 26
City of Alma
SRF & SWQIF Draft Project Plan
Table 14: Proposed Design Criteria
Sewers
Pump Stations
Storm Drain
Footing Drain Disconnects
Proposed pipe size to provide 25 year peak flow, based on
full pipe flow (no surcharge)
Minimum pipe grades as specified in Recommended
Standards for Wastewater Facilities (10 States Standards),
Chapter 30.
Firm pump capacity equal to 25 year peak flow.
Provide 4” Interceptor Drain behind curb line in areas where
storm sewer is not available to provide outlet for
disconnected footing drains
Storm drain to be constructed at 0.50% gradient (minimum)
and connect to existing catch basins along street
Identify potential footing drain connections by inspecting
buildings in Focus Area 1 and 2, which have not been
inspected
Disconnect footing drains from sewer lead, and direct to a
sump
Install sump pump and direct discharge to storm drain
B. Controlling Factors
The primary factor controlling the design is addressing capacity problems resulting from wet
weather flows. The selected alternative was developed to achieve this goal through a
combination of both reducing inflow and adding capacity.
The city’s wastewater system has other needs, particularly sections of sewer that will require
repair, replacement, or rehabilitation because of its age. Since these needs are not urgent, the city
plans to work on addressing them over a longer period of time to reduce the impact of costs to
users.
C. Sensitive Features
Portions of the selected alternative will be constructed in the floodplain of the Pine River. The
proposed alternative will have no direct impact on other sensitive features such as wetlands,
prime or unique agricultural lands, archaeological sites, or the habitat of a threatened or
endangered species.
A map showing the proposed project area and sensitive features is included in Appendix 17.
D. Evaluation of Environmental Impacts
1. Impacts Resulting from Construction and Operation of Selected Alternative
There will be short-term impacts resulting from construction.
Excavation will disturb soils and turf areas resulting in the potential for erosion. The
contractor will be required to provide measures to minimize the impact of erosion and to
restore surfaces quickly to minimize the exposure.
During construction, there will be increased noise resulting from the operation of construction
equipment. Contractor’s working hours will be limited to reduce the potential for noise
during night time, Sundays, and holidays.
Page 27
City of Alma
SRF & SWQIF Draft Project Plan
Construction of the project will result in short term economic benefits to the city and region.
Some contractors and workers hired for construction of the project will likely be residents of
the area. During construction, local businesses will benefit from purchases by the contractor
and workers for such items as fuel, meals, lodging, aggregate, and supplies.
2. Project Impacts
Completion of the project will have a positive impact on the environment. Additional sewer
capacity and the removal of known sources of inflow will reduce the likelihood of sanitary
sewer overflows and sewer backups. Additional collection and treatment capacity provided
by the project will provide the ability to provide service to new industries and businesses,
resulting in economic benefits to the city and the region.
The short term impacts due to construction of the project will be outweighed by the positive
benefits of the project. The impacts from construction activities are temporary and provisions
will be made to limit their impact. No lasting impact from the disruption of construction is
anticipated. However, the completed project will provide the city the ability to provide for
the treatment of wastewater from the city and adjacent areas for some time, minimizing
impacts to the environment.
3. Indirect Impacts
Completion of the project will help maintain the integrity and reliability of the city’s
wastewater system for its existing customers.
Expansion of sewers to “new” areas is possible with or without the planned project.
Although no large residential, commercial, or industrial projects are planned; it is possible
that some areas now utilized for farming or other uses may developed for these uses.
Development in these “new” areas is expected to occur slowly as economic conditions
improve. Unused homes, commercial buildings, industrial facilities, and brownfields will
minimize the threat to “new” areas.
4. Cumulative Impacts
Social and economic impacts are not likely to be of a cumulative nature. Alma is a wellestablished, stable community. The proposed project is designed to address issues with their
existing wastewater facilities so that the city can continue to maintain their stable social and
economic environment.
To avoid burdening wastewater customers with sharp rate increases, the city has prioritized
the needs of the wastewater facilities. Needs of highest priority are planned initially and
other needs are planned to be completed over a period of several years. This will allow rates
to be increased gradually to support the needed upgrades and rehabilitation of the city’s
wastewater system.
E. Mitigation
Permits will be obtained prior to construction to allow for excavation, work within the MDOT
right-of-way, and work within the floodplain of the Pine River. The contractor will use
construction methods which reduce the potential for impact.
Silt fence and other protections will be utilized for work sites so that the potential for erosion and
sedimentation is reduced.
Page 28
City of Alma
SRF & SWQIF Draft Project Plan
Where work is planned in the floodplain of the Pine River, the surface will be restored to similar
contours and surface materials as presently existing. This will prevent any long-term impact to
the floodplain.
VIII. Schedule
The following schedule has been developed for completing the selected alternative.
State Government Fiscal Year
2011
2012
2013
2014
1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q
Design of Sewer Upgrades
Design of Pump Station Upgrades
Development of Plan for Footing Drain Disconnection
Permitting
Bidding
Construction - Sewers & Pump Stations
Construction - Footing Drain Collection
Construction - Footing Drain Disconnection
A. Staging of Construction
Other upgrades and needs of the city’s wastewater facilities have been identified. These needs
include:
•
•
•
•
•
Continued study to identify and evaluate inflow from the east side of the city
Video Investigation of complete sewer system to identify and prioritize sections requiring
repair, replacement, or rehabilitation
Replacement of the Pine River interceptor
Correction of excess inflow or additional capacity from the east side of the city
Repair, replace, or rehabilitate existing sections of sewer where video inspection indicates
structural failure of threat of structural failure
The city is working on the first item above, and plans to begin work on the second one within the
next couple of years. The city plans to work to complete all of these over the next twenty years;
the exact schedule will be determined based upon the findings of the initial investigations and
study, and resulting priorities. Completing this work over such a long period will reduce the
impact of the work on rate payers.
B. Authority to Implement the Selected Alternative
The City of Alma owns and is solely responsible for the operation of the wastewater system.
Wastewater service is provided to Pine River Township and Arcada Township on a wholesale
basis. The city has the authority and jurisdiction to complete all of the work included in the
selected alternative.
The city has drafted a revised Sewer Use ordinance which provides the city the authority to
complete the disconnection of footing drains which are included in the selected alternative. The
Page 29
City of Alma
SRF & SWQIF Draft Project Plan
new ordinance has been presented to city council and it is expected to be adopted in June. A copy
of the new ordinance is included in Appendix 18.
C. User Costs
City wastewater customers are charged a readiness-to-serve fee plus a commodity charge based
upon actual consumption. On July 1, 2010 the wastewater rates for the typical residential
customer are as follows:
•
•
Readiness-to-Serve:
Commodity:
$15.47 per month
$2.07 per 1,000 gallons
A typical monthly bill for a residential customer, using 5,000 gallons of water per month would
be $25.82.
To pay debt for the proposed project, a residential bill based on 5,000 gallons of water use is
projected to increase by $7.62 per month. The city plans that rates will be increased
incrementally over the four year period planned for designing and completing construction.
Table 15 demonstrates how rates can be increased incrementally.
Table 15: Projected Sewer Bill
Residential Sewer Bill
(5,000 gallons per month)
July 1, 2010
$25.82
July 1, 2011
$27.70
July 1, 2012
$29.60
July 1, 2013
$31.48
July 1, 2014
$33.44
Additional details regarding rates are included in Appendix 19.
D. Public Participation
Information regarding public participation will be added when available.
Page 30