HomeMy Public PortalAboutMaline Creek E. coli TMDL ARAP_FINAL_Oct_2020
MALINE CREEK E. coli TMDL
ASSUMPTIONS AND REQUIREMENT
ATTAINMENT PLAN
October, 2020
Prepared by Metropolitan St. Louis Sewer District in coordination with its MS4 co-permittees.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
TABLE OF CONTENTS
1.0 Introduction and Purpose ....................................................................................................................... 3
1.1 Maline Creek E. coli TMDL ....................................................................................................... 3
1.2 MS4 Permit Requirements .......................................................................................................... 6
2.0 E. coli Bacteria and its Potential Sources .............................................................................................. 6
2.1 Sanitary Sewer Infrastructure ...................................................................................................... 7
2.2 Individual Sewage Disposal Systems ......................................................................................... 9
2.3 Urban Stormwater Runoff ......................................................................................................... 10
2.4 Riparian Conditions .................................................................................................................. 10
2.5 Illicit Straight Pipe Discharges ................................................................................................. 10
3.0 TMDL Implementation Activities ....................................................................................................... 10
3.1 St. Louis County Phase II Stormwater Management Plan ............................................................. 11
3.1.1 MCM #1, Public Education and Outreach of Stormwater Impacts .................................. 11
3.1.2 MCM #2, Public Involvement and Participation .............................................................. 12
3.1.3 MCM #3, Illicit Discharge Detection and Elimination ..................................................... 13
3.1.4 MCM #4, Construction Site Stormwater Runoff Control ................................................. 14
3.1.5 MCM #5, Post-Construction Stormwater Management in
New Development and Redevelopment ............................................................................ 15
3.1.6 MCM #6, Pollution Prevention Good Housekeeping for Municipal Operations .............. 16
3.2 Project Clear .................................................................................................................................. 17
3.2.1 Sanitary Sewer Overflow Control Master Plan................................................................. 17
3.2.1.1 Sewer System Evaluation Survey (SSES) ................................................................ 17
3.2.1.2 Master Plan Projects ................................................................................................. 18
3.2.2 Capacity, Management, Operations, and Maintenance Program ......................................... 20
3.2.3 Fats, Oil, and Grease Program ............................................................................................. 21
3.3 TMDL Best Management Practices Targeting Bacteria ................................................................ 21
4.0 Evaluation ............................................................................................................................................ 24
LIST OF FIGURES
Figure 1. Impaired reach of Maline Creek as described in the Maline Creek E. coli TMDL, and watershed
location in St. Louis County, Missouri ......................................................................................... 4
LIST OF TABLES
Table 1. TMDL requirements for E. coli bacteria at specific flows in Maline Creek, WBID 1709 ............ 5
Table 2. Summary of Sanitary Sewer Gravity Pipes by Pipe Diameter and Material in Maline
Creek Watershed as of February 11, 2020 ..................................................................................... 7
Table 3. Summary of Sanitary Sewer Pipes by Pipe Diameter and Material that have
Received Cured in Place Lining in Maline Creek Watershed as of February 11, 2020 ................. 8
Table 4. Summary of Capacity and Non-Capacity Overflows and
Bypasses for Maline Creek Watershed, 01/01/2017 - 12/31/2019 ................................................ 9
Table 5. TMDL Best Management Practices Targeting Bacteria in the Maline Creek Watershed ........... 23
APPENDICES
Appendix A. SSO Control Master Plan Projects in the Maline Creek Watershed
Appendix B. Bacteria and Nutrient Best Management Practices Strategy Review
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1.0 Introduction and Purpose
Maline Creek first appeared on Missouri’s Section 303d list of impaired waters for elevated
concentrations of Escherichia coli (E. coli) bacteria in 2012. In-stream concentrations of E. coli have
been found to exceed Missouri’s water quality criterion for its designated use of Whole Body Contact
Recreation Category B, which is set at 206 E. coli counts per 100 milliliters of water (206 counts/100mL).
According to Missouri’s 303d listing methodology, a water designated for Whole Body Contact
Recreation Category B use is determined to be impaired by bacteria if the geometric mean in a given
recreational season exceeds 206 counts/100mL in any of the last three years with available data. At least
five samples are needed from a single recreational season, which is defined as the period from April 1
through October 31. Maline Creek remained on Missouri’s Section 303d list of impaired waters for E.
coli from 2012 to 2018. On April 25, 2018, the United States Environmental Protection Agency
(USEPA) approved Missouri’s Total Maximum Daily Load (TMDL) in Maline Creek watershed for
Pathogens as indicated by E. coli1.
As required by the Federal Clean Water Pollution Control Act, the Missouri Department of Natural
Resources (MDNR) issues the Metropolitan St. Louis Sewer District (MSD), St. Louis County, and 59 St.
Louis County municipalities a general operating permit to discharge authorized stormwater from the
Municipal Separate Storm Sewer System (MS4) servicing the Plan Area to waters of the state. The most
recent permit (General Operating Permit MOR040005) was issued on December 14, 2016 and requires
regulated MS4s identified in a TMDL with an applicable Wasteload Allocation (WLA) to implement
steps toward the attainment of the applicable WLA in accordance with 40 CFR 122.44(k)(2) and (3). In
this case, MSD and its co-permittees are required to develop an Assumptions and Requirement
Attainment Plan (ARAP) to address applicable assumptions and requirements in the Maline Creek
Watershed TMDL for Pathogens as indicated by E. coli (referred to herein as Maline Creek E. coli
TMDL).
The purpose of this document is to fulfill requirements in the MS4 permit issued to MSD and its co-
permittees, specifically Section 3.1. MS4s Subject to Total Maximum Daily Loads (TMDL). This TMDL
ARAP will address the aggregated wasteload allocations assigned to the MS4 area in the Maline Creek E.
coli TMDL. Procedures and activities to be implemented in accordance with the MS4 permit are
provided herein. Most importantly, this TMDL ARAP includes a description of implementation activities
and best management practices (BMPs) that will be used to target known sources of E. coli bacteria
specific to the Maline Creek watershed, as well as a prioritized schedule for their implementation. BMP
effectiveness will be evaluated after implementation, and those found to be ineffective will be revised or
replaced accordingly. Both the Maline Creek E. coli TMDL and TMDL Implementation Plan2 were used
in the development of this TMDL ARAP.
1.1 Maline Creek E. coli TMDL
Maline Creek is located in north St. Louis County. The most upstream extent of Maline Creek occurs just
northeast of the Interstate 170 overpass at St. Charles Rock Road, along the municipal border between St.
John and Charlack. From this point, Maline Creek flows to the north past Interstate 70 and then generally
east towards its confluence with the Mississippi River, located in the northern limits of the City of St.
Louis. In total, Maline Creek is approximately 9.3 miles long. The reach identified as WBID 1709 is
approximately 7.2 miles and is listed as Class C water3. As described in the Maline Creek E. coli TMDL,
WBID 1709 and its impaired length is 0.6 miles and this segment starts at Bellefontiane Road and flows
1 Missouri Department of Natural Resources Water Protection Program. 2018. Total maximum daily load (TMDL) for Maline
Creek, St. Louis County and St. Louis City. Pollutants of concern: Pathogens. Submitted: July 11, 2017. Approved: April 25,
2018. 36pp. 2 Missouri Department of Natural Resources Water Protection Program. May 2, 2017. Total maximum daily load implementation
plan for Maline Creek St. Louis County and St. Louis City. Pollutants of concern: Pathogens. 22pp. 3 Missouri’s Water Quality Standards at 10 CSR 20-7.031 Table H. March 31, 2018.
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east to the City of St. Louis. WBID 1709 has been assigned the following designated uses: Livestock
and Wildlife Protection; Irrigation; Protection and Propagation of Fish, Shellfish, and Wildlife – Warm
Water Habitat; Human Health Protection; Secondary Contact Recreation; and, Whole Body Contact
Recreation Category B. As described in the Maline Creek E. coli TMDL, the reach of Maline Creek
impaired by bacteria is shown in Figure 1.
Maline Creek watershed covers approximately 26.6 square miles and is comprised of karst geology,
including a single gaining stream segment in the upper region of the Black Jack Creek subwatershed. The
Maline Creek watershed includes portions of the following MS4 co-permittees: St. Louis County
(unincorporated areas), Bel-Nor, Bel-Ridge, Bellefontaine Neighbors, Berkeley, Black Jack, Calverton
Park, Charlack, Cool Valley, Dellwood, Ferguson, Florissant, Hazelwood, Jennings, Moline Acres,
Normandy, Norwood Court, Overland, Riverview and St. John.
Figure 1. Impaired reach of Maline Creek as described in the Maline Creek E. coli TMDL, and
watershed location in St. Louis County, Missouri.
A TMDL is a calculation that sets the amount of pollutant a water body can assimilate without exceeding
the water quality criterion for that particular pollutant. The TMDL allocates the pollutant load among
three components:
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1) Wasteload allocation (WLA) for all point sources and MS4 Operators;
2) Load allocation (LA) for all nonpoint sources and natural background sources; and,
3) Margin of Safety (MOS) to account for any uncertainty in data or model assumptions.
The TMDL is equal to the sum of the wasteload allocation, load allocation, and margin of safety as
expressed in the following equation:
TMDL = ΣWLA + ΣLA + MOS
The Maline Creek E. coli TMDL was developed using a numeric target concentration of 206
counts/100mL and a load duration curve for WBID 1709. The target concentration represents Missouri’s
water quality criterion of 206 E. coli counts per 100mL of water. The load duration curve applied average
daily discharge data (cfs) between March 23, 2004 and December 31, 2016 from the United States
Geological Survey (USGS) gage station USGS 07005000 at Bellefontaine Neighbors. Discharge data
were corrected according to the ratio of the impaired drainage area, as delineated by its outlet, to the gage
drainage area. The numeric target concentration was multiplied by the corrected average daily discharge
and a conversion factor to calculate the daily load (counts/day) at specific discharges.
Regulation of stormwater discharges from systems owned or operated by MS4s in Maline Creek
watershed is covered under two MS4 permits. The first MS4 permit is held by MSD and its 60 co-
permittees (referred to as MSD MS4 permit from hereon) and covers a jurisdiction of approximately 94.5
percent of the watershed. The second is a site specific MS4 permit held by the Missouri Department of
Transportation (Permit No. MO-0137910) and covers the remaining 5.5 percent. There are no other
permitted facilities in Maline Creek watershed that might reasonably contribute to bacteria loading, thus
all of the WLA was assigned to the MS4 area. Furthermore, since it was not possible to accurately
disaggregate E. coli loading for each MS4, the WLA was assigned as an aggregate wasteload to the total
MS4 area. Please see Table 1, adapted from the Maline Creek E. coli TMDL1.
Table 1. TMDL requirements for E. coli bacteria at specific flows in Maline Creek, WBID 17091.
Percentile Flow
Exceedance
Flow
(cfs)
TMDL
(counts/day)
MS4 WLA
(counts/day)
LA
(counts/day)
95 0.97 4.90E+09 4.90E+09 0
75 3.33 1.68E+10 1.68E+10 0
50 6.58 3.32E+10 3.32E+10 0
25 14.63 7.37E+10 7.37E+10 0
10 54.93 2.77E+11 2.77E+11 0
cfs =cubic feet per second; WLA = wasteload allocation; LA = load allocation
While on-site wastewater treatment systems are noted in the TMDL as a potential nonpoint source, they
are not expected to contribute to the bacteria impairment if properly functioning and were assigned a load
allocation of zero. In addition, the catchments that contribute stormwater runoff to the outfalls permitted
under the MSD MS4 permit were not identified during development of the TMDL. Therefore, the
nonpoint source load allocation (LA) was not disaggregated from the MS4 WLA and no load allocations
were assigned in the Maline Creek E. coli TMDL.
The margin of safety component is considered implicit because of conservative assumptions used in the
TMDL model, the use of multiple years of stream discharge data collected under a complete range of
conditions, reduced uncertainty of the sources of the bacteria impairment, and remediation of bacteria
sources through MSD’s Project Clear program. In addition, the daily load estimated values used the
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recreation-season geometric mean while at the same time omitting bacteria decay rates, which are
overlapping conservative assumptions.
1.2 MS4 Permit Requirements
Missouri General Operating Permit MOR040005 (issued on December 14, 2016), Section 3.1.1, requires
any regulated MS4 identified in a USEPA approved or established TMDL with an applicable WLA to
implement steps towards the attainment of applicable WLA in accordance with 40 CFR 122.44(k)(2) and
(3). Section 3.1.2 of the permit states the permittee shall develop a TMDL ARAP to address the TMDL’s
assumptions and requirements where applicable. The TMDL ARAP shall be incorporated into the
Stormwater Management Plan (SWMP) and include, at a minimum, the following:
3.1.2.1 A process to identify potential sources of the pollutant(s), BMPs to be implemented to address the
sources within their MS4, a prioritization of those actions, and a schedule including beginning
and ending milestones by month and year. The schedule for the implementation of the TMDL
ARAP shall be completed as soon as practicable, but is not limited to the term of this operating
permit (i.e. 5 years) as attainment can take years or even multiple permit terms.
3.1.2.2 BMPs developed or designed with a purpose of reducing the pollutant(s) of concern. Each BMP
shall contain a description of the BMP, the purpose of the BMP, and the expected result of the
BMP.
3.1.2.3 Measurable goals shall be established for each BMP or in conjunction with multiple BMPs. Each
measurable goal shall contain a statement clearly indicating how it will be established to
determine the appropriateness of identified BMPs and progress toward the expected results of the
BMP. Measurable goals shall be quantifiable; however, if it is not feasible to utilize a measurable
goal that is quantifiable, then the permittee shall provide justification indicating why the
measurable goal cannot be quantifiable. If applicable, measurable goals shall also utilize interim
and completion milestone dates, and a periodic frequency of measurement to document progress.
It is recommended that interim and final milestone dates are established with a format of month
and year. If the format of month and year cannot be utilized, the permittee shall ensure that
schedules have the minimum of 1st, 2nd, 3rd, 4th, and 5th year of the operating permit.
3.1.2.4 An iterative process to be utilized by the permittee that documents how each BMP is evaluated
and subject to replacement or modification. The permittee shall apply reasonable further progress
by replacing or modifying ineffective BMPs with effective BMPs.
2.0 E. coli Bacteria and its Potential Sources
E. coli bacteria commonly inhabit the intestines of warm-blooded animals and their feces. In-stream
contributions of E. coli usually originate from humans, pets, livestock, and wildlife. There are a variety
of pathways E. coli might enter a waterway, such as stormwater runoff from agriculture and urban lands,
failing septic systems and illicit connections, and discharges from sewage infrastructure related to
wastewater treatment. The presence of E. coli measured at high concentrations indicates contamination
by fecal matter. While the broad group of E.coli bacteria are mostly considered harmless, its presence is
used an indicator of other pathogenic bacteria, viruses, and other microorganisms. Diseases from those
pathogens can cause eye, ear, nose, throat, and respiratory infections, as well as gastrointestinal illness.
Missouri’s Section 303d lists of impaired waters from 2012-2018 note the source of E. coli bacteria in
Maline Creek as urban runoff/storm sewers. The Maline Creek E. coli TMDL describes several specific
sources of E. coli bacteria including the sanitary sewer system, onsite wastewater treatment systems
(referred to herein as individual sewage disposal systems), urban stormwater runoff, riparian corridor
conditions, and to a lesser extent, straight pipe illicit discharges. In particular, human sources of
pathogens (e.g., sanitary sewer discharges and onsite systems) are considered a higher human health risk
depending upon the duration and type of exposure. The following information is a summary of all
potential sources of bacteria to Maline Creek.
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2.1 Sanitary Sewer Infrastructure
There are no permitted facilities that discharge domestic or municipal wastewater treatment systems in the
Maline Creek watershed. MSD’s Bissell Point Wastewater Treatment Plant which receives wastewater
generated in the Maline Creek watershed is located outside the watershed, about 3.5 miles to the south of
Maline Creek’s confluence with the Mississippi River. Sanitary sewer infrastructure is present
throughout the watershed however, comprising approximately 438.6 miles of pipe. A summary of public
sanitary sewer pipes found in the watershed is provided in Table 2, and a summary of sewer pipes that
have received cured-in-place lining rehabilitation is presented in Table 3.
Table 2. Summary of Sanitary Sewer Gravity Pipes by Pipe Diameter and Material in Maline
Creek Watershed as of February 11, 2020.
Pipe
Diameter
(inches)
VCP Plastic RCP Cast Iron
or DIP
CP Other Sub-Total
-- Length in Feet
3 -- -- -- 16 -- -- 16
4 253 152 -- -- -- -- 404
6 13,531 5,093 -- 325 -- -- 18,949
8 1,092,200 656,380 3,682 5,918 18,143 285 1,776,609
9 136 -- -- -- -- -- 136
10 51,512 52,286 -- 1,560 1,975 149 107,482
12 50,347 44,582 5,577 1,210 177 119 102,012
14 -- 326 -- -- -- -- 326
15 29,005 31,236 1,738 246 478 136 62,840
16 309 -- 43 111 -- -- 463
18 27,945 28,804 1,273 2,384 265 44 60,715
20 -- -- -- 280 -- -- 280
21 5,032 11,754 1,558 -- -- -- 18,344
24 8,555 11,858 3,003 328 -- 264 24,008
27 2,911 1,736 1,751 -- -- -- 6,398
30 7,273 4,709 3,624 637 -- -- 16,243
33 2,642 4,228 4,652 -- -- -- 11,523
36 1,143 7,020 3,643 574 -- 359 12,739
39 -- -- -- -- -- 460 460
42 -- 5,222 10,730 -- -- -- 15,951
45 -- -- -- -- -- 276 276
48 1,483 7,826 4,592 -- -- -- 13,901
54 -- 1,174 6,878 -- -- -- 8,053
56 -- -- -- -- -- 95 95
60 1,293 886 14,376 148 67 863 17,632
66 -- 118 7,535 -- -- -- 7,653
72 247 40 6,936 -- 3,217 -- 10,440
78 -- -- 5,443 -- -- 210 5,653
84 -- -- 1,496 -- -- -- 1,496
96 -- -- 3,465 -- -- -- 3,465
108 -- -- 734 -- -- -- 734
120 -- -- 4,631 -- -- -- 4,631
132 -- -- 167 -- -- -- 167
144 40 -- 2,938 -- 637 -- 3,615
192 -- -- 1,993 -- 33 -- 2,025
Total 1,295,856 875,431 102,459 13,738 24,993 3,260 2,315,737
VCP is vitrified clay pipe; RCP is reinforced concrete pipe; DIP is ductile iron pipe; CP is concrete pipe.
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Table 3. Summary of Sanitary Sewer Pipes by Pipe Diameter and Material that have
Received Cured-in-Place Lining in Maline Creek Watershed as of February 11, 2020.
Pipe
Diameter
(inches)
VCP PVC RCP Cast
Iron DIP
CP Other Sub-Total
-- Length in Feet
6 2,077 252 -- -- -- -- -- 2,329
8 469,008 3,679 431 90 359 39,299 1,508 514,375
10 35,525 514 164 -- 372 3,361 -- 39,936
12 24,940 167 2,111 46 370 444 29 28,107
14 -- -- -- -- 232 -- -- 232
15 17,567 397 1,381 57 379 -- 76 19,856
18 9,644 637 4,102 -- 226 -- -- 14,610
21 1,300 1,048 5,685 -- -- -- -- 8,033
24 6,714 -- 1,528 -- -- -- -- 8,242
27 1,158 -- 269 -- -- -- -- 1,426
30 945 -- 1,206 -- -- -- -- 2,151
33 2,586 -- 1,643 -- -- -- -- 4,228
36 -- 277 877 -- -- -- 335 1,488
42 1,619 -- 3,210 -- -- -- -- 4,829
54 -- -- 1,174 -- -- -- -- 1,174
60 -- -- 119 -- -- 492 -- 611
Total 573,082 6,972 23,901 193 1,937 43,597 1,947 651,629
VCP is vitrified clay pipe; PVC is polyvinyl chloride; RCP is reinforced concrete pipe; DIP is ductile iron pipe;
CP is concrete pipe.
In addition to sewer pipes, there are 10,528 sanitary manholes in the Maline Creek watershed that fall
under public or private ownership. Manholes are mostly constructed of brick, cast-in-place concrete,
precast sections of concrete and other materials. There are two sanitary pump stations located within the
watershed that are owned and operated by MSD. The first is located just northeast of the intersection of
Paul Avenue and South Florissant Road, and the second is located where Riverview Drive Crosses
Maline Creek just upstream of its mouth with the Mississippi River. Force mains in Maline Creek
watershed total nearly 1.6 miles.
Of the 13 constructed sanitary sewer overflow (SSO) points first described in the TMDL, there are
currently four that remain. Per MSD’s Project Clear Program, three constructed SSOs (BP-287, BP-291,
and BP-597) are scheduled for elimination prior to 2024. The fourth constructed SSO (BP-317) is to be
eliminated between 2029-2033. With the successful completion of sanitary relief and I/I reduction efforts
in the watershed, flow monitoring studies have been planned to evaluate the potential for removing BP-
317 ahead of schedule.
Unintended overflows from the sanitary system however may still occur from time to time as a result of
blockages, line breaks, power failures and vandalism. A summary of capacity and non-capacity
overflows and bypasses that reached a receiving stream in the Maline Creek watershed for the period of
January 1, 2017 through December 31, 2019 is provided in Table 5.
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Table 4. Summary of Capacity and Non-Capacity Overflows and
Bypasses for Maline Creek Watershed, 01/01/2017- 12/31/2019.
Cause Count Remedy
Debris Blockage 2 Cleaned/Cleared
Root Blockage 1 Cleaned/Cleared
Equipment Failure 1 Repaired
Broken Pipe 1 Repaired
Other 1 Cleaned/Cleared
Total 6 --
As part of the SSO Master Plan requirement in MSD’s federal consent decree4, MSD conducted a Sewer
System Evaluation Survey (SSES) for the Maline Creek watershed. SSES findings related to sewer
defects are described in Section 3.2.1.1 of this ARAP, and SSO Master Plan remedial projects are
described in Section 3.2.1.2 and Appendix A.
2.2 Individual Sewage Disposal Systems
Individual sewage disposal systems are considered nonpoint sources of pollution. Failing systems are
known sources of bacteria that can enter nearby streams through surface and subsurface flows. As
referenced in the Maline Creek E. coli TMDL, a study conducted by the Electric Power Research Institute
(EPRI) suggests that up to 50 percent of the systems in Missouri may be failing5.
In a recent survey conducted specifically for MSD to gather information on environmental awareness in
MSD’s service area, out of 570 residents contacted by either mail or online, 4% (22) indicated they had a
septic system at their home6. When residents were asked if their septic system had been serviced in the
last five years, 64% (14) of those indicated it had, 14% (3) said it had not, and 23% (5) were unsure6. Of
18 residents asked about the age of their system, 28% (5) said their septic system was more than 30 years
old6.
The prevalence of individual sewage disposal systems in the Maline Creek watershed has been reduced
over time. According to MSD Rules and Regulations, treatment using a septic system is not allowed when
public sanitary sewers are within 200 feet of any point on a property and determined to be available, or
when a lot is less than three (3) acres in size. Additionally, completion of MSD’s Supplemental
Environmental Project resulted in the closure of three individual sewage disposal systems in this
watershed7. Still, there are approximately 284 parcels in the Maline Creek watershed suspected of not
having a connection to the public sewer1. Non-sewered parcels include those with structures and those
without, though it is not directly known how many parcels with existing structures have an individual
sewage disposal system in operation. Therefore contributions of bacteria from failing individual sewage
disposal systems are likely, however the scope of the problem within the Maline Creek watershed is not
entirely known.
4 United States of America and the State of Missouri, and the Missouri Coalition for the Environment Foundation v. Metropolitan
St. Louis Sewer District, No. 4:07-CV-1120. 5 Electric Power Research Institute. 2000. Advanced On-Site Wastewater Treatment and Management Market Study: Volume 2:
State Reports. TR-114870. 224pp. 6 ETC Institute for Metropolitan St. Louis Sewer District. 2017. Metropolitan St. Louis Sewer District environmental awareness
survey. ETC Institute. 47pp. 7 Metropolitan St. Louis Sewer District. 2017. SEP Completion Report. 41pp.
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2.3 Urban Stormwater Runoff
Urban stormwater runoff is known to contain high levels of bacteria and is another potential contributor
of E. coli to Maline Creek. According to a study conducted by USGS8 median E. coli densities from six
stream locations in MSD’s service area were strongly correlated with the percentage of upstream
impervious cover. Runoff from both pervious and impervious areas has the potential to pick up and
transport bacteria from domestic and wild animal waste. Pet waste may enter local waterways from
residential areas, as well as areas open to the public, such as dog parks, parks, trails, or other recreational
areas utilized by pet owners. Wild animals like raccoons inhabiting the storm system or nuisance geese
residing on local ponds are also potential sources. Additionally, bird droppings on roadways can easily
be carried into the storm system and transported to streams during rain events. Waste from livestock,
poultry, pets, and wildlife are all known to contribute to E. coli concentrations in urban streams. On
average, 10 percent of E. coli in six metropolitan St. Louis streams was traced to dogs and another 20
percent to geese8. Note, this USGS8 study included data from collected from a single sample site in
Maline Creek.
Urban runoff discharges from the two MS4 permitted systems are considered potential point sources of E.
coli to Maline Creek. As previously discussed, the catchments that contribute stormwater runoff to the
outfalls permitted under the MSD MS4 permit were not identified during development of the TMDL.
Stormwater runoff from areas not served by the MS4s is considered a nonpoint source. However, the
nonpoint source load allocation (LA) was not disaggregated from the MS4 WLA and no load allocations
were assigned in the Maline Creek E.coli TMDLs for WBID 1709.
2.4 Riparian Conditions
Riparian corridor conditions in the watershed were listed in the Maline Creek E. coli TMDL as a likely
source of bacteria. The riparian corridor of streams in the Maline Creek watershed, extending 30-meters
on each side of the channel, consists mostly of land cover types containing various degrees of
development and imperviousness1. Notably, more than 58 percent of the riparian corridor in this
watershed is categorized as having low to high intensity development and greater than 20 percent
impervious coverage1. Open space development, which contains less than 20 percent impervious cover,
makes up approximately 30 percent of the riparian corridor1. Riparian areas comprised of low to high
intensity development or even open space development are potential sources of bacteria when stormwater
runoff comes in contact with pet and wildlife wastes.
2.5 Illicit Straight Pipe Discharges
Illicit straight pipe discharges occur where household waste is discharged directly to a stream or area of
land, and are different from illicitly connected sewers. Due to the presence of a sewerage system
throughout the Maline Creek watershed, illicit straight pipe discharges are not expected to be significant
contributors of E. coli. However, there is potential for private sewer laterals to fail on occasion and
discharge sewage to waterways. Illicit discharges such as these have been found across MSD’s service
area through Illicit Discharge Detection and Elimination work as required under Minimum Control
Measure #3 of the MS4 permit. Discharges from failed sewer laterals are resolved by the homeowner,
usually with partial funding assistance from a local lateral repair program.
3.0 TMDL Implementation Activities
The implementation of activities provided in this ARAP will aim to reduce bacteria loading in Maline
Creek. In large part, those activities will be implemented through ongoing programs already being
executed. The two main implementing programs are the St. Louis County Phase II Stormwater
8 Wilkison, D.H., Davis, J.V. 2010. Occurrence and sources of Eschericia coli in metropolitan St. Louis streams, October 2004
through September 2007: U.S. Geological Survey Scientific Investigations Report 2010-5150. 57pp.
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Management Plan (Third Term Permit 2017-2021) and MSD’s consent decree obligations, established as
part of the United States of America and the State of Missouri, and the Missouri Coalition for the
Environment Foundation v. Metropolitan St. Louis Sewer District, No. 4:07-CV-1120. Additional
activities beyond these two programs will harness information generated through existing MSD
maintenance operations with the goal of developing and implementing further bacterial reduction.
3.1 St. Louis County Phase II Stormwater Management Plan
The St. Louis County Phase II Stormwater Management Plan (Third Term Permit 2017-2021), referred to
herein as the Stormwater Management Plan (SWMP), was developed in compliance with the MS4 permit
issued to MSD and its co-permittees. The permit requires MS4s, MSD and its co-permittees, to
implement activities via an iterative process to reduce the discharge of pollutants to the maximum extent
practicable (MEP) into the MS4 for the goal of attainment with Missouri’s Water Quality Standards. The
SWMP, which was approved by MDNR on June 18, 2018, contains six minimum control measures
(MCM) that include measurable activities for addressing requirements under Section 4.2 of the MS4
permit. Goals for each activity are set in each year of the permit, and annual reports are submitted to
MDNR regarding the status of each goal. Goals are reviewed annually and the SWMP may be updated as
needed or following renewal of the MS4 permit.
Continued implementation of the SWMP through the iterative process will result in a significant
reduction of pollutants discharged to waters in the plan area, including the discharge of E. coli bacteria to
Maline Creek. The result of implementing each activity will be reported through the SWMP annual
reporting process.
The following is a summary of SWMP activities expected to reduce bacteria contributions to Maline
Creek. Each activity references its corresponding goal in the SWMP. Prioritization activities, measurable
goals, implementation schedules, and milestones for the activities described below will be consistent with
those already identified in the SWMP. Please review the SWMP for a complete description of all
activities under each MCM along with their schedule for implementation9. All activities in the SWMP
shall be reviewed and evaluated for effectiveness at the end of year five of the MS4 permit to determine if
they should be replaced or modified in the next permit cycle and SWMP.
3.1.1 MCM #1, Public Education and Outreach of Stormwater Impacts
MSD and its co-permittees are required to implement a public education program to distribute educational
material to the community or conduct equivalent outreach activities about the impact of stormwater
discharges on waterbodies and steps the public can take to reduce pollutants in stormwater runoff. This
program targets several pollutant sources that directly or indirectly address bacteria, including: pet waste;
yard management; individual sewage disposal systems; land disturbance; and fats, oils, and grease (FOG).
Under MCM#1, the current SWMP lists 16 individual activities that are intended to identify entities that
may have an impact on stormwater, identify target audiences to foster nonpoint source pollution and
water quality awareness, and ultimately increase awareness and positive behavior changes for those in the
community. Of those 16 activities, 11 pertain to bacterial reduction and are noted as follows:
1. Collect a stormwater education survey to develop a baseline of water quality and nonpoint
source pollution awareness and behaviors, and identify target audiences (Goal 6 of SWMP).
The survey includes bacteria related topics such as the disposal of household cooking oils
and grease, inspection and maintenance of septic systems, and disposal of pet waste.
2. Develop a database of all K-12 public and private schools in the plan area, which is to be
used for outreach purposes and tracking schools that provide stormwater education (Goal 7
of SWMP). Bacterial pollution prevention is a component of stormwater education.
9 The SWMP is available on MSD’s website, https://msdprojectclear.org/.
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3. Develop and distribute stormwater messages to improve the public’s awareness of water
quality protection (Goal 8 of SWMP). Messaging includes topics such as disposal of pet
waste and maintenance of individual sewage disposal systems, both being potential sources
of bacteria in the watershed.
4. Maintain and provide a library of stormwater education materials that can be used at public
events and distributed to various audiences (Goal 9 of SWMP). Some of those materials
will include information on bacteria pollution and prevention.
5. Provide presentations and educational materials to families and homeowners for the purpose
of fostering nonpoint source pollution and water quality awareness (Goal 10 of SWMP).
Presentations and educational materials will include information on bacteria pollution and
prevention.
6. Post pet waste signs in parks in order to foster nonpoint source pollution and water quality
awareness (Goal 11 of SWMP). This effort will directly address pet waste as a source of
bacteria.
7. Maintain a database of community partners with an interest in water pollution education for
the purpose of fostering nonpoint source pollution and water quality awareness (Goal 12 of
SWMP). Water pollution education will include information on bacteria pollution and
prevention.
8. Provide educational materials to industrial entities, waste haulers, and food service
establishments in order to foster nonpoint source pollution and water quality awareness in
the community (Goal 13 of SWMP). Educational materials will include information on
bacteria pollution and prevention.
9. Provide presentations and educational materials to trade associations, schools, and watershed
groups (Goal 14 of SWMP). This activity will foster nonpoint source pollution and water
quality awareness in the community and increase positive behavior change. Presentations
and education materials will include information on bacteria pollution and prevention.
10. Partner with community organizations to provide stormwater information to a broad
audience for the purpose of fostering nonpoint source pollution and water quality awareness,
and increasing positive behavior change (Goal 15 of SWMP). Stormwater information will
include topics associated with bacteria pollution and prevention.
11. Develop and advertise videos to be utilized in social media platforms (Goal 16 of SWMP).
Messaging will include information on bacteria pollution and prevention.
3.1.2 MCM #2, Public Involvement and Participation
Under MCM #2, MSD and its co-permittees implement a public involvement/participation program that
provides opportunities for the public in development and oversight of the SWMP, as well as opportunities
for involvement with the permittee’s renewal application. Collectively, there are 11 activities under
MCM#2. Activities such as marking storm drains, distributing Enviroscape® watershed models for
school presentations, participating in annual cleanup events, and providing resources to citizen volunteer
organizations that promote green infrastructure and other healthy water programming ultimately improve
nonpoint source pollution and water quality awareness. Of the 11 activities under MCM#2, there are five
that pertain to bacterial reduction and are noted as follows:
1. Provide training to educators, watershed groups members, and others on how to use
Enviroscape® watershed models with the purpose of engaging volunteers on how to educate
students on sources of pollution and best practices (Goal 23 of SWMP). Training will
include information on bacteria pollution and prevention.
2. Provide Enviroscape® watershed models for community use which will help foster nonpoint
source pollution and water quality awareness (Goal 24 of SWMP). Pollution education will
include information on bacterial pollution and best practices.
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3. Provide stormwater drain marking instructions and supplies to volunteers in order to help
foster nonpoint source pollution and water quality awareness (Goal 25 of SWMP). Inlet
marking is intended to deter illegal dumping to the stormwater system, including material
contaminated with bacteria such as pet waste.
4. Develop a storm drain marking map to help facilitate participation in drain marking
opportunities (Goal 26 of SWMP). Improved participation will increase the number of
marked drains and decrease illegal dumping, including those that may contain bacteria.
5. Provide resources to volunteer organizations that promote green infrastructure and other
healthy water programming in order to foster nonpoint source pollution and water quality
awareness (Goal 27 of SWMP). Efforts will include the distribution of educational material
containing information on sources of bacteria and practices to reduce or prevent pollution.
3.1.3 MCM #3, Illicit Discharge Detection and Elimination
As part of MCM #3, MSD carries out an Illicit Discharge Detection and Elimination (IDDE) Program.
An illicit discharge is any discharge to the stormwater system that is not composed entirely of stormwater,
and may result from illegal dumping, a direct connection from the sanitary sewer to the storm sewer, or an
indirect connection from improper surface discharges to the storm sewer. Under this program, MSD
surveys all natural channels in the plan area at least once every five years, inspects outfalls for illicit
discharges, responds to reports of illegal dumping, and conducts timely elimination of prohibited
discharges. In the past, staff conducting illicit discharge surveys have discovered and eliminated illegal
dumping of pet waste, leaking sewer lines, and failing private sewer laterals and onsite septic systems.
MSD’s implementation of the IDDE program is expected to be one of the most impactful actions to
improve water quality in the Maline Creek watershed.
There are 15 activities implemented under MCM #3, all of which either target sources of bacteria directly
or facilitate the process of identifying and eliminating bacteria sources. Those activities are as follows:
1. Maintain a Geographic Information System (GIS) of stormwater outfalls and receiving
streams (Goal 28 of SWMP). This GIS is used to locate and view outfalls in the plan area,
and in the process identify and investigate sources of bacteria.
2. Provide map update work orders to track modifications to the sewer map for the purpose of
maintaining current information on the storm sewer system in the plan area (Goal 29 of
SWMP). This activity will improve the identification, tracking, and elimination of potential
sources of bacteria.
3. Enforce MSD ordinance No. 15048, and others as required (Goal 30 of SWMP). Ordinance
No. 15048 serves as MSD’s legal enforcement tool for eliminating prohibited discharges,
including those that may be a source of bacteria.
4. Survey all natural channels identified in MSD’s stormwater GIS once every five years (Goal
31 of SWMP). This activity will lead to detecting and eliminating illicit discharges,
including those that are a source of bacteria.
5. Respond to reports of illegal dumping, which will include detecting and eliminating sources
of bacteria (Goal 32 of SWMP).
6. Maintain operating procedures for field testing and surveying to help identify chemicals
indicative of illicit discharges (Goal 33 of SWMP). Field screening provides for timely and
efficient illicit source identification and elimination, including sources of bacteria.
7. Maintain and annually review findings from channel surveys for the purpose of identifying
priority areas for potential monitoring and follow-up work (Goal 34 of SWMP). This activity
ensures there is follow-up on potential sources of pollutants to the stormwater system,
including bacteria.
8. Review representative water quality data collected by MSD to prioritize investigation areas
(Goal 35 of SWMP). Data is used to identify pollutant sources, including those for bacteria.
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9. Develop a tabular database and GIS layer of areas that may utilize individual sewage disposal
systems for the purpose of assisting with illicit discharge investigations (Goal 36 of SWMP).
This activity directly pertains to bacteria as a pollutant.
10. Develop a tabular database and GIS layer of properties that have participated in a sewer
lateral repair program in order to assist with illicit discharge investigations (Goal 37 of
SWMP). This activity directly pertains to bacteria as a pollutant.
11. Maintain operating procedures for tracing illicit discharges from the public sewer system for
the purpose of timely detection and elimination of pollutant sources, including those that are a
source of bacteria (Goal 38 of SWMP).
12. Maintain operating procedures for the timely elimination of illicit discharges, including those
that are a source of bacteria (Goal 39 of SWMP).
13. Maintain an enforcement plan for the timely elimination of illicit discharges, including those
that are a source of bacteria (Goal 40 of SWMP).
14. Maintain and distribute brochures, door hangers, and other communication tools that inform
about the hazards associated with illegal discharges and improper disposal of waste (Goal 41
of SWMP). The purpose of this activity is to foster stormwater nonpoint source pollution
awareness and positive behavior change in the community, and it will address sources of
bacteria.
15. Provide outreach communication tools to sources of non-stormwater discharges that could be
substantial contributors of pollutants into the MS4, including bacteria (Goal 42 of SWMP).
The purpose of this activity is to foster stormwater nonpoint source pollution awareness and
positive behavior change in the community.
Please note, information gathered for goals 35, 36, and 37 of the SWMP will also be used to support
bacteria reduction strategies listed in Section 3.3 TMDL Best Management Practices Targeting Bacteria.
3.1.4 MCM #4, Construction Site Stormwater Runoff Control
Under MCM #4, MSD and its co-permittees develop, implement, and enforce a program to reduce
pollutants in any stormwater runoff to their regulated Small MS4 from construction activities that result in
land disturbances greater than or equal to one acre. Reduction of stormwater discharges from a
construction activity disturbing less than one acre is included in the program if that construction activity is
part of a larger common plan of development or sale that would disturb one acre or more.
Each incorporated municipality has the authority for construction permitting and inspection services.
Some co-permittees provide full permitting and inspection services independently, while others have
adopted St. Louis County’s ordinance and contract with St. Louis County Code Enforcement to meet
permitting and inspection needs. While bacteria contributions from land disturbance sites is expected to
be low, the potential for discharges of E. coli from sanitary facilities at construction sites is reduced
through inspections and enforcement. There are eight individual activities implemented under MCM #4,
of which five specifically relate to bacteria through retaining waste on site or by ensuring sediment and
erosion controls are properly installed. Those five activities are as follows:
1. Maintain written procedures and guidance materials for operators to follow (Goal 45 of
SWMP). This activity will help prevent sanitary waste from leaving the site and potentially
entering a water course.
2. Maintain written procedures and guidance materials for permittees to follow (Goal 46 of
SWMP). This activity will address bacteria by requiring development pre-construction
planning and appropriate installation and maintenance of sanitary waste facilities.
3. Maintain written procedures to receive, respond to, and track public inquiries and complaints
(Goal 47 of SWMP). This activity will address bacteria by providing timely responses to
complaints of sanitary waste leaving a site.
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4. Maintain written procedures and checklists for permittees to follow during SWPPP
inspections (Goal 48 of SWMP). This activity will address bacteria by ensuring BMPs for
sanitary waste facilities are properly installed and maintained.
5. Inspect land disturbance sites per land disturbance program ordinance (Goal 49 of SWMP).
This activity will address bacteria by ensuring BMPs for sanitary waste facilities are properly
installed and maintained.
3.1.5 MCM #5, Post-Construction Stormwater Management in New Development and
Redevelopment
MSD and its co-permittees require developers to implement appropriate strategies and controls to address
post-construction runoff from new development and redevelopment projects that disturb one acre of land
or more, including projects less than one acre that are part of a larger common plan of development or
sale. MSD and co-permittee ordinances ensure all applicable public and private development projects
involving stormwater management are reviewed and approved by MSD.
All projects are required to assess existing site conditions and identify sensitive areas and natural
resources on site. The Rules and Regulations require that site designers prepare a site development plan
that adequately protects sensitive areas and natural resources and does not generate unwarranted amounts
of stormwater pollution. This plan may be based on the current version of the Site Design Guidance
document on MSD’s website. Development sites regulated in the MS4 are required to apply strategies
that reasonably mimic predevelopment runoff conditions by reducing runoff volume to calculated
predevelopment levels. MSD requires all stormwater facilities to be provided and designed in accordance
with provisions contained in the “Rules and Regulations and Engineering Design Requirements for
Sanitary Sewer and Stormwater Drainage Facilities,” as amended.
The Bacteria and Nutrient Best Management Practice Strategy Review, conducted by Geosyntec
Consultants and reported in a memorandum dated December 23, 2016 (Appendix B), evaluated MSD’s
ongoing stormwater management facility selection based on bacteria and nutrient reduction effectiveness
and helped characterize BMP implementation to the MEP. This review found that nearly 70% of built or
planned structural facilities in the MS4 area scored high for removal of bacteria. Those structural
facilities included bioretention basins, infiltration facilities, permeable pavements, and ponds. Continued
implementation of these stormwater facilities and enhancements as recommended in the memorandum
will help meet bacteria reduction targets.
Maintenance responsibility for approved post-construction stormwater management facilities belongs to
the owner. MSD’s authority to ensure stormwater facilities are maintained is covered under MSD
Ordinance No. 15048. Owners submit annual reports on facility condition and MSD conducts inspections
of each stormwater facility at least once every three years.
There are eight activities implemented under MCM #5 in the current SWMP, all of which will help to
reduce bacteria contamination of stormwater. Those activities are as follows:
1. Follow MSD and co-permittee ordinances, as well as MSD Rules and Regulations, which
require developers and plan reviewers to implement appropriate strategies and controls to
address post-construction runoff (Goal 51 of SWMP). Included among those strategies and
controls, is the use of certain stormwater management facilities that remove bacteria from
stormwater.
2. Follow the plan review process of executing maintenance agreements for the environmental
compliance inspection process in order to ensure long-term operation of stormwater facilities,
including those that remove bacteria (Goal 52 of SWMP).
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3. Utilize the technology matrix in MSD’s stormwater management toolbox and maintain
existing strategies (Goal 53 of SWMP). This activity will require developments to implement
appropriate strategies and controls to address post-construction runoff, and will result in
implementing activities to the MEP, including those that target bacteria.
4. Co-permittees will review and update parking ordinances and/or policies as needed in order
to reduce impervious parking areas and barriers to incorporating green infrastructure (Goal 54
of SWMP). This activity will optimize use of pervious areas, helping to remove bacteria
from stormwater.
5. Maintain an optional conceptual review process to provide developers with a plan review
assessment of appropriate strategies and controls to address post-construction runoff (Goal 55
of SWMP). This activity will identify opportunities for water quality protection, including
identifying stormwater facilities that can help remove bacteria early in the project planning
phase.
6. Make the Site Design Guidance document available to provide developers and plan reviewers
a way to implement effective stormwater management controls (Goal 56 of SWMP). This
activity will lead to utilizing effective stormwater facilities, protecting sensitive areas, and
help to remove bacteria from stormwater.
7. Use pre-condition assessment with early stage project planning which will lead to utilizing
effective stormwater facilities, protecting sensitive areas, and help to remove bacteria from
stormwater (Goal 57 of SWMP).
8. Inspect all water quality stormwater facilities utilizing key performance indicators to
demonstrate compliance (Goal 58 of SWMP). This activity will ensure the long term
operation of stormwater facilities, including those that remove bacteria from stormwater.
3.1.6 MCM #6, Pollution Prevention Good Housekeeping for Municipal Operations
Under MCM #6, MSD and its co-permittees implement an operation and maintenance program that
includes a training component and has the ultimate goal of preventing or reducing pollutant runoff from
municipal operations. Common municipal operations that are addressed by an Operations and
Maintenance Program include: general housekeeping and operation and maintenance; vehicle/equipment
repair and maintenance operations; vehicle/equipment washing; facility repair, remodeling, and
construction; cleaning and maintenance of roadways, highways, bridges, and parking facilities;
maintenance of parks, green spaces, trails, and landscaping; cleaning and maintenance of drainage
channels, storm sewers, and inlet structures; operation and maintenance of recycling facilities; and, water
quality impact assessment of flood management projects. Written Operation and Maintenance Program
procedures help to ensure pollution controls are properly installed and maintained. Training provided to
staff covers pollution prevention and control techniques that may apply to the municipal operations noted
above, as well as identifying and reporting illicit discharges. There are 10 specific activities included
under MCM #6 in the SWMP, and three of those help to reduce bacteria in stormwater. Those activities
are as follows:
1. Provide training to all MSD and co-permittee employees who work in municipal operations
impacted by stormwater in order to prevent and reduce stormwater pollution from municipal
operations (Goal 59 of SWMP). Training includes information on reporting illicit discharges
such as failing septic systems, which will help to reduce bacteria in stormwater.
2. Install stormwater facilities with the construction of municipal buildings and roadways,
where feasible, for the purpose of providing pollutant controls (Goal 63 of SWMP). Certain
facilities will help remove bacteria from stormwater.
3. MSD and all co-permittees are to maintain a written Operation and Maintenance Program to
prevent and reduce runoff from municipal operations (Goal 65 of SWMP). The written
program includes guidelines for posting pet waste signs in public parks and maintaining
disposal stations, which will help to reduce bacteria in stormwater.
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3.2 Project Clear
MSD’s implementation of Project Clear has and will continue to result in reduced bacteria loading to
Maline Creek. Project Clear is a long-term effort by the Metropolitan St. Louis Sewer District (MSD)
that focuses on three categories of work: get the rain out; repair and maintain; and building system
improvements. Get the rain out focuses on preventing excess stormwater from entering the sewer system
through a variety of project types, including downspout disconnections, and rainscaping. Repair and
maintain continues the work MSD has done to repair, maintain, and renew the existing sewer system, on a
faster timeline. Building system improvements involves new construction of wastewater management
structures, including deep underground tunnels and above-ground storage tanks.
Project Clear activities meet obligations required under the federal consent decree. Among those
obligations, MSD must eliminate all constructed sanitary sewer overflow outfalls no later than December
31, 203310. Other Project Clear strategies that involve sewer inspection, maintenance, and repair and
rehabilitation will reduce occurrences of sanitary sewer overflows as well. The following sections
describe MSD’s work under Project Clear and the federal consent decree that will address bacteria
loading in Maline Creek.
3.2.1 Sanitary Sewer Overflow Control Master Plan
MSD’s SSO Control Master Plan developed in compliance with the consent decree describes specific
measures that will result in the elimination of all constructed SSO outfalls, all known SSOs, building
backups, and/or that are necessary to ensure there is adequate capacity in the sanitary sewer system to
collect, convey, and treat anticipated wet weather flows under current and projected future conditions.
Remedial measures used to address capacity limitations and eliminate bypassing may include the removal
of I/I sources and increases in the capacities of sewer pipes, force mains, and pump stations. The SSO
Control Master Plan is required to eliminate 85% of the constructed SSO outfalls by December 31, 2023.
Elimination of up to 15% of the constructed SSO outfalls may occur after December 31, 2023, but all
must be eliminated no later than December 31, 2033.
3.2.1.1 Sewer System Evaluation Survey (SSES)
As part of the SSO Control Master Plan, MSD performed a SSES for the Maline Creek watershed11. The
purpose of the SSES was to identify 1) areas with excessive inflow/infiltration (I/I) causing or
contributing to SSOs and building backups, 2) known SSOs within the watershed, 3) physical conditions
and design constraints of pump stations and force mains that contribute to SSOs and building backups, 4)
physical and/or structural conditions of pipes, manholes, and structures in the sanitary sewer system that
contribute to SSOs and building backups, 5) sources of I/I determined to have excessive I/I rates, and 6)
stormwater cross connections and discovered unauthorized direct connections.
The SSES identified areas of the watershed with excessive I/I which were causing or contributing to SSOs
or building backups. That assessment was based on the following criteria: existence of constructed SSO
outfalls; number of sewer backup insurance claims; number of customer service requests; water quality
impacts; and, I/I rate estimates. The highest priority study areas were identified throughout the Maline
Creek watershed, but were most prevalent in the central portion of the watershed.
Physical/structural condition and design constraints of sanitary sewer infrastructure were also described in
the SSES report. The two operating pump stations previously mentioned in Section 2.1 Sanitary Sewer
10 MSD’s consent decree was amended on June 22, 2018. This amendment extended the construction schedule for certain
combined sewer overflow storage tunnels in the River Des Peres watershed by five years. MSD also agreed to invest $20 million
in green infrastructure in its Lemay Service Area/River Des Peres Watershed. 11 Metropolitan St. Louis Sewer District. 2013. Maline Creek watershed sewer system evaluation survey. Completed December
31, 2013. 1,058pp.
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Infrastructure were designed for wet weather purposes. During the period of April 27, 2007 and April
27, 2012, no known sanitary sewer overflows were attributed to pump stations. There were no design
constraints associated with any of the forcemains. CCTV investigations of 3,196 sewer reaches
comprising approximately 30.0% of the sewers in the watershed, were carried out in suspected problems
areas (thus are not indicative of the entire watershed). Of the sewer reaches that were televised,
approximately 55.0% had major to moderate structural issues or root intrusion warranting strong or
medium attention by MSD.
I/I studies were conducted in higher priority areas of the watershed identified by their potential for
causing or contributing to SSOs or building backups. I/I was attributed to both public and private defects.
Public defects are found on sewers and manholes located on public ground or easement and maintained
by MSD. Private defects are found on private property. Public defects included indirect connections,
mainline defects, manhole cover defects, manhole frame defects, and manhole structure defects. There
were four direct connections (e.g. stormwater inlet connected to the sanitary system) of inflow among the
public defect findings. Private sources of I/I were the result of the following defective components:
downspouts; cleanouts; laterals; drains (i.e. yard drains, driveway drains, basement entry drains,
foundation drains, etc.); and, plumbing inside buildings. Overall, most defects in the study were the result
of defective cleanouts, manhole frames, manhole structures, private drains and private laterals. Defect
categories that may have the greatest impact on wet weather flows (average flow per defect) associated
with overall I/I included direct connections, downspouts, indirect connections and private drains.
The SSES resulted in a total of 15,200 defects with an associated flow estimated at 45,536 gallons per
minute (gpm) from both public and private sources. In total, there were 8,910 (59%) private defects with
an associated flow estimated at 27,180 gpm (60%). From the public sewer system, there were 6,290
(41%) defects with an associated flow estimated at 18,356 gpm (40%). Furthermore, the number of
inflow defects totaled 13,315 (88%) providing an associated flow estimated at 41,734 gpm (92%).
Whereas, infiltration defects totaled 1,885 (12%) providing an associated flow estimated at 3,802 gpm
(8%). The SSES report for the Maline Creek watershed contains a complete summary of I/I estimated
flows and attributed sewer defects.
3.2.1.2 Master Plan Projects
As a result of the SSES, 29 SSO Control Master Plan projects were originally scheduled in the Maline
Creek watershed. Appendix A includes a table with all SSO Control Master Plan projects for the Maline
Creek watershed. Projects listed in the table include schedules for I/I reduction related to both public and
private sources, sanitary relief and storage, other system improvements. Public and private work includes
remedial measures to address their respective defects as described in the previous section. All work is
usually scheduled ahead of Master Plan dates to ensure compliance with timelines in MSD’s consent
decree.
Eighteen (18) projects in the SSO Control Master Plan for the Maline Creek watershed address sewers
affected by I/I. The purpose of I/I reduction is to repair and replace public and private sewers where
inflow and infiltration cause or contribute to SSOs or building backups. Inflow occurs when stormwater
enters the sanitary sewer through direct connections. Sources of inflow can include connections from
roof drains, defective laterals and lateral cleanouts, and other drains for yards, driveways, basement
entries, foundations, etc. Infiltration refers to groundwater that enters the sanitary sewer system through
cracks and other openings in defective or deteriorated sewers. Cracks or openings may be caused by age
related deterioration, loose joints, installation errors, damage, or root infiltration. Inflow and infiltration
sources influence sewer flows differently during storm events, with inflow impacting the sewer
immediately and infiltration impacting the sewer over an extended period of time.
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Ten (10) projects focus on sanitary relief rather than I/I reduction. The purpose of sanitary relief is to
increase the capacity of the sewer to handle wet weather peak flows without experiencing surcharging
sufficient to cause SSOs, including causing failure of the largest pump in any pumping station and/or
primary power failure to any pumping station. Of these 10 projects, the need for Bissell Hills Sanitary
Relief/St. Cyr Rd to Leeton Ave was addressed by earlier I/I reduction activities and is no longer
necessary. Perhaps most noteworthy of the sanitary relief projects is the Maline Creek Storage Facility
accomplished through Upper Maline Trunk Sanitary Relief Phase IV Sections A, B and C. In early 2016,
MSD awarded an $82.8 million contract for the construction of this storage facility. The Maline Creek
Storage Facility is a 2,700-foot long, 28-foot diameter tunnel that extends from Chain of Rocks Drive to
Church Road, and is 175 feet below ground. This facility is designed to store excess stormwater and
sewage during extreme wet weather. When the rain subsides, a pump station transfers the stored flow to
the Bissell Point Wastewater Treatment Plant for treatment. This project will reduce the amount of
combined sewer overflow discharge into Maline Creek by directing flow through three “intake structures”
to the storage facility. Construction is anticipated to be completed in late 2020.
One (1), project, Upper Jeske Park Lateral Sanitary Relief (Scott Dr to Cardigan Dr), focused on the
removal of a constructed SSO, but also included sanitary relief and private I/I removal. This project was
addressed by work performed under SSO Control Master Plan project Upper Jeske Park Lateral Sanitary
Relief (SKME-314).
Collectively, the 29 SSO Control Master Plan projects include 38 unique phases (See Appendix A). Of
these, two (2) are in pre-design status, four (4) have their designs completed and are planned, five (5) are
under construction, two (2) phases intended for sanitary relief were determined not necessary after I/I
reduction was performed and 25 phases have been completed. The 25 phases which have been completed
addressed private and public I/I reduction, sanitary relief or constructed SSO removal for the following
projects:
· Ashbrook I/I Reduction (Ashbrook Dr and Chambers Rd)
· Bellefontaine #2 Lateral Sanitary Relief (BP -287) (Coburg Lands Dr)
· Bissell Hills Sanitary Relief/Calumet I/I Reduction (BP-317)
· Dacey Branch I/I Reduction (BP-313)
· Forestwood Lateral Sanitary Relief (SKME-321)
· Kappel (Partial) I/I Reduction (Exuma Dr and Glen Owen Dr)
· Lang Royce Lateral Sanitary Relief (SKME-320)
· Maline I/I Reduction & Sewer Rehabilitation (BP-289) (Colony Dr)
· Marietta Dr Storm Separation and I/I Reduction (BP-292)
· Mead Sanitary Relief (Landwehr Ln to Hemlock Dr)
· Springdale I/I Reduction (Rolling Dr and Smithfield Pl)
· Suburban I/I Reduction (Harrison Dr and Suburban Ave)
· Sun Valley I/I Reduction
· Upper Jeske Park Lateral Sanitary Relief (SKME-314)
· Upper Jeske Park Sanitary Relief (Scott Dr to Cardigan Dr)
· Upper Maline Trunk Sanitary Relief Phase IV Section A
As noted previously, there are four constructed SSOs that remain active in Maline Creek watershed.
Those constructed SSOs will be eliminated through the completion of four SSO Control Master Plan
projects. Those constructed SSOs along with their respective projects are as follows:
· BP-287, Bellefontaine #2 Sanitary Relief (BP -287) (Chambers Rd to Coburg Lands Dr)
· BP-291, Lang Royce Sanitary Relief (Fargo Dr to Floridale Ct)
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· BP-317, Dorothy Sanitary Relief (Chambers Rd to McCartney Ln)
· BP-597, Upper Maline Trunk Sanitary Relief Phase IV Section B
The remaining Master Plan projects are scheduled for anticipated completion from 2020 through 2033.
These projects will correct defects and eliminate sources of I/I that deprive the system of capacity. By
completing Master Plan projects the frequency of SSO occurrences and the release of bacteria into the
watershed will be reduced. The status of projects listed in Appendix A will be submitted with each
SWMP Annual Report. Completion of Master Plan projects will aid in the reduction of bacteria to
Maline Creek.
3.2.2 Capacity, Management, Operations, and Maintenance Program
MSD’s Capacity, Management, Operations, and Maintenance (CMOM) Program operates with goal of
maintaining established service levels and minimum performance standards. MSD’s CMOM Program
conducts the following activities:
1. Inspects 280 miles of sanitary sewer by CCTV each year, and annually reports location and
number of miles of sewer pipe inspected.
2. Acoustically inspects all sewers 15 inches or less in the separate system on a six year cycle. All
sewers that score an acoustic inspection rating of 0 to 5 will be cleaned. Clean all sewers greater
than 15 inches and less than or equal to 21 inches in the separate system on a six year cycle.
Clean all sewers less than or equal to 21 inches in the combined system on a five year cycle.
Clean all sewers greater than 21 inches as needed. MSD annually reports the number of miles
and locations of all sewer pipes that are acoustically inspected or cleaned.
3. Inspects 15,000 manholes annually and performs manhole frame adjustments as needed (there is
no yearly target for manhole frame adjustments), and performs repairs, rehabilitations, and/or
replacements on all manholes with a condition rating of 4 or 5 within one year of discovery.
MSD annually reports locations and number of manholes inspected, total number of manhole
frame adjustments performed, and manholes that were permanently
repaired/rehabilitated/replaced.
4. Permanently repairs, rehabilitates, and/or replaces at least 90 miles of sewer pipe each year (the
target of 90 miles will be reduced to 65 miles in 2022), and repairs all acute defects within one
year of discovery. MSD annually reports the locations and number of miles of sewer pipes that
were repaired/rehabilitated/replaced, as well as the locations and number of acute defects that
were repaired.
5. Inspects all 271 pump stations. Inspection frequency is no less than monthly for all collection
system pump stations, no less than twice per month for pump stations between 1 million gallons
per day (MGD) to 5 MGD in peak hydraulic capacity, and no less than weekly for pump stations
greater than 5 MGD in peak hydraulic capacity. Overflow Regulation Systems (ORS) and Relief
pump stations are inspected no less than monthly regardless of capacity. Collectively, MSD is
required to perform 3,905 pump station inspections each year. MSD annually reports the number
of inspections for each pump station as well as its capacity range.
6. Visual inspections and non-destructive testing of force mains. Force mains categorized as high-
risk are inspected visually each year and by non-destructive testing once every three years. Force
mains categorized as medium-risk are inspected visually once every two years and by non-
destructive testing once every six years. Force mains categorized as low-risk are inspected
visually once every five years. All defects discovered during inspection and testing are repaired
within one year. MSD annually reports locations and numbers of force main assets in each risk
category that have undergone visual inspection, non-destructive testing, and have been
repaired/replaced per risk.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
21
CMOM activities will be carried out within the Maline Creek watershed and can be expected to contribute
to reduced bacteria loading. CMOM activities will be reported as required under the MSD’s consent
decree, and will not be reported as part of this ARAP. Implementation of BMP #4 in Section 3.3 TMDL
Best Management Practices Targeting Bacteria however, may help detect the CMOM Program Plan’s
impact on bacteria loading to Maline Creek.
3.2.3 Fats, Oil, and Grease Program
The consent decree also includes requirements for MSD to control fats, oil, and grease (FOG) to ensure
their accumulations are not restricting the capacity of the sewer system and causing sanitary sewer
overflows. Under the FOG Control Program Plan, MSD identifies and inspects commercial
establishments/food service establishments (FSEs) and industrial facilities prone to FOG accumulations.
Facilities located in problem areas with reoccurring grease blockages that result in SSOs or in areas with
collection system defects are inspected on a periodic schedule with greater frequency (i.e. quarterly, semi-
annual, or annual). Routine periodic FSE inspections of FOG equipment are conducted every two to five
years when the sewer is in a moderate to low risk area. FSE inspection frequency may be greater than
five years in low risk areas with exceptionally large diameter sewer pipes. Other FSE inspections can
occur in response to FOG related complaints, or more randomly when investigators notice a new facility
while in the field, or if an existing facility has undergone a name change. Within MSD’s service area
there are approximately 4,400 facilities having the potential to discharge significant amounts of FOG into
the sanitary sewer system.
Within the Maline Creek watershed, there are 270 active FSEs and 19 that are listed as having been
decommissioned12. Between 2017 and 2019, 1,388 FSE inspections were performed, resulting in 56
enforcement actions. Over this same period, no sanitary sewer overflows were found to be caused by
grease blockages.
FSE inspections and enforcement actions are reported annually under MSD’s consent decree, and thus
will not be reported in this ARAP. Instead, implementation of BMP #4 in Section 3.3 TMDL Best
Management Practices Targeting Bacteria, may help detect the FOG Program’s impact on bacteria
loading to Maline Creek.
3.3 TMDL Best Management Practices Targeting Bacteria
Beyond activities carried out under the SWMP and MSD’s consent decree, specific TMDL BMPs will be
implemented in order to further reduce the bacteria loading in Maline Creek. These BMPs are
specifically designed to improve the monitoring and management of potential sources of bacteria in the
watershed. TMDL BMPs are shown in Table 6, and are set to begin the first year following removal of
the last constructed SSO in Maline Creek watershed, which is scheduled in 2034.
As mentioned in Section 3.2.1.2 Master Plan Projects, the status of SSO Control Master Plan projects
listed in Appendix A will be reviewed annually and submitted with each SWMP Annual Report. Should
removal of the last constructed SSO occur early, the schedule of TMDL BMP implementation activities
as outlined in Table 6 will be adjusted accordingly. Adjustments to the schedule would be submitted to
DNR with the SWMP annual report.
Prior to the start of TMDL BMP implementation, similar ARAP activities will have already been
conducted in Fishpot Creek watershed and others impaired by bacteria within MSD’s MS4 area. This
will lend valuable experience and other “lessons learned” which can be harnessed to ensure that effective
approaches are implemented in Maline Creek watershed.
12 FSE data regarding active and decommissioned establishments was obtained on 2/24/2020.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
22
Among the seven TMDL BMPs listed in Table 6, BMPs will include visual inspections of the storm
sewer to identify potential sources of bacteria (TMDL BMP #2) and subsequent response efforts to
eliminate those sources that have been confirmed (TMDL BMP #3). Currently MSD utilizes crawl crews
and CCTV inspections to inspect and assess the condition of large and small storm sewer systems.
Findings from these inspections will include the location of direct connections into storm sewer mains,
inlets, and manholes. Where private connections are discovered, they will be reported to MSD’s Division
of Environmental Compliance to investigate for and identify sources of E. coli bacteria that feed into the
private storm sewer connections. Based on the findings of the investigations, appropriate action will be
taken to eliminate discovered sources of E. coli bacteria associated with the connection. For instance, this
could be an improperly connected house lateral, septic system, or a drainage area served by a drain that is
populated by pet owners or livestock. Work pertaining to TMDL BMPs #2 and #3 is scheduled through
2038. Data obtained from visual inspections of the storm sewer system, including but not limited to
CCTV and Crawl Crew inspections, conducted in other watersheds with bacterial TMDL ARAPs in the
MS4 area will be used to evaluate the effectiveness of visual storm sewer inspections overall and help
determine the best methods for this activity in Maline Creek watershed. It is anticipated that visual storm
sewer inspections will be improved and refined over time, becoming more effective at identifying and
eliminating bacteria sources. While TMDL BMPs #2 and #3 are planned though 2038, they may be
completed ahead of schedule or remain ongoing.
In accordance with MS4 Permit Sections 3.1.3.3 and 3.1.3.4, TMDL BMPs listed in Table 6 of this
section will be implemented according to the provided schedule only after this TMDL ARAP receives
MDNR’s approval. Therefore, MSD respectfully requests MDNR’s approval of this TMDL ARAP.
Implementation activities in the SWMP and MSD’s consent decree will be carried out according to their
previously determined and ongoing schedules. All TMDL BMPs shall be reviewed and evaluated for
effectiveness at least three times: 1) prior to the start of the TMDL BMP implementation schedule in
Table 6; 2) at the end of year five of each MS4 permit (the MS4 permit has not been developed for the
implementation period and this date is not yet known); and 3) following completion of all TMDL BMP
implementation activities.
During development of this Maline Creek E. coli TMDL ARAP, MSD and its co-permittees are operating
in the fourth year of the third term SWMP and MS4 permit. By the start of TMDL BMP implementation
in Maline Creek, SWMP activities will have undergone one or more iterative reviews. In addition, the
Maline Creek Storage Facility will be in operation, reducing combined sewer discharges into Maline
Creek. MSD will continue to monitor water quality within Maline Creek as a result of these efforts, and
factor that data into decisions to adjust certain TMDL BMPs and their implementation schedules.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
23
Table 5. TMDL Best Management Practices Targeting Bacteria in the Maline Creek Watershed.
1BMP is based on outcome of the SWMP BMP #36 (third term). The map will be used for channel inspections conducted in the fourth term MS4 permit. 2BMP is based on outcome of SWMP BMP #37 (third term). 3Denotes period for iterative review of BMP effectiveness. In 2034, there will be a review of TMDL BMPs prior to implementation. Iterative review will also take place at the end of Permit Year 5, which is currently not known for the implementation period.
# BMP Description BMP Purpose Expected
Result of BMP
Measurable Goals and Milestone Dates
Permit Year 4,
2020
Permit Year 5,
2021
2022-
2033 20343 2035 2036 2037 20383
BMP Evaluation
Process/Criteria
1
Determine extent of
rehabilitated sewers along
Maline Creek and
tributaries. Compare to in-
stream E.coli data.
Identify extent and
percent of rehabbed
sewers within defined
proximity to Maline Creek
and tributaries. Identify
potential relationships
with instream E. coli and
need for sewer
rehabilitation work.
Map and summary
table of rehabbed
sewers within
defined proximity
to Maline Creek
and tributaries.
None None None Generate map and
summary table.
Generate map and
summary table.
Generate map and
summary table.
Generate map and
summary table.
Generate map and
summary table.
Map and summary table developed and
updated.
2
Identify potential sources of
bacteria through visual
inspections of the storm
sewer system.
Identify sources of
bacteria to Maline Creek.
Summary of
bacteria findings.
None None None Commence visual
inspections.
Report findings
from 2034.
Continue visual
inspections.
Report findings
from 2035.
Continue visual
inspections.
Report findings
from 2036.
Continue visual
inspections.
Report findings
from 2037.
Continue visual
inspections.
Summary table with bacteria findings
developed.
3
Respond to or eliminate
potential human related
sources of bacteria identified
through visual inspections of
the storm sewer systems.
Reduce bacteria loading to
Maline Creek.
Summary of
response actions.
None None None Respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2034
response actions.
Continue to respond
to bacteria findings
and eliminate illicit
discharges
identified during
visual inspections.
Report 2035
response actions.
Continue to respond
to bacteria findings
and eliminate illicit
discharges
identified during
visual inspections.
Report 2036
response actions.
Continue to respond
to bacteria findings
and eliminate illicit
discharges
identified during
visual inspections.
Report 2037
response actions.
Continue to respond
to bacteria findings
and eliminate illicit
discharges
identified during
visual inspections.
Summary table with response actions
developed.
4
Assess E. coli data collected
by MSD in previous year
and evaluate loading and
trends.
Track E. coli levels and
bacteria loading.
Summary table
with E. coli
measurements,
loading rates, and
trends.
None None None Summarize 2033
E. coli loading and
trend.
Summarize 2034
E. coli loading and
trend.
Summarize 2035
E. coli loading and
trend.
Summarize 2036
E. coli loading and
trend.
Summarize 2037
E. coli loading and
trend.
Summary table with E. coli measurements,
loading rates, and trend developed and
updated.
51
Update database of
properties that may utilize
an individual sewage
disposal system in Maline
Creek watershed.
Have a database of
properties that may have
an individual sewage
disposal system to identify
potential sources of
bacteria.
Map and list of
properties with an
individual sewage
disposal system.
None None None Develop map and
list of properties.
None None None None Map and list of properties with an
individual sewage disposal system
developed.
62
Update database of
properties that participated
in a sewer lateral repair
program in Maline Creek
watershed.
Track improvements to
problematic infrastructure
and elimination of
potential sources of
bacteria.
Have a database of
properties that
participated in a
lateral repair
program.
None None None Develop map and
list of properties
None None None None Map and list of properties with repaired
sewer laterals developed.
7
Summarize maintenance of
individual sewage disposal
systems documented by
MSD’s Hauled Waste
Program.
Have a list of properties
that maintain their
individual sewage
disposal system.
Develop a list of
properties that
maintain their
individual sewage
disposal system.
None None None Obtain 2033 records
from Hauled Waste
Program, add to list,
and report.
Obtain 2034 records
from Hauled Waste
Program, add to list,
and report.
Obtain 2035 records
from Hauled Waste
Program, add to list,
and report.
Obtain 2036 records
from Hauled Waste
Program, add to list,
and report.
Obtain 2037 records
from Hauled Waste
Program, add to list,
and report.
List of properties that maintain their
individual sewage disposal system
developed.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
24
4.0 Evaluation
Activities described in this TMDL ARAP will target bacteria sources in Maline Creek and aim to reduce
the overall bacteria load contributing to its impaired status. All activities will be carried out through
implementation of the SWMP, Project Clear and the federal consent decree, or as scheduled in Section
3.3 of this document, TMDL Best Management Practices Targeting Bacteria.
TMDL BMPs listed in Section 3.3 of this document will be implemented according to the schedule found
in Table 5. With the first efforts completed by the Fishpot Creek bacteria TMDL ARAP and others
commencing prior to this watershed, opportunities for “lessons learned” exist. Outcomes of earlier efforts
accomplished in those watersheds will be considered for implementation into this ARAP, either as a
modification to a proposed activity or an additional activity. Such changes to this ARAP schedule could
occur either prior to, or after its commencement, and would be subject to MDNR approval.
TMDL BMPs #2 and #3 are scheduled through 2038, but with lessons learned, both BMPs may be
completed ahead of schedule or remain ongoing in order to maximize the effectiveness of visual storm
sewer inspections at identifying and eliminating sources of pathogens. Each TMDL BMP shall be
reviewed and evaluated for effectiveness as described earlier to determine if they should be replaced or
modified in order to achieve further progress towards reducing the bacteria load to Maline Creek. TMDL
BMP effectiveness will be largely based on water quality data as evaluated under TMDL BMP #4.
In line with MS4 Permit Section 3.1.2.1, implementation of the Maline Creek E. coli TMDL ARAP will
be completed as soon as practicable, but is anticipated to span years or even multiple permit terms.
MSD & MS4 Co-permittees
Maline Creek E. coli TMDL ARAP
Appendix A
SSO Control Master Plan Projects in the Maline Creek Watershed
MSD & MS4 Co-permittees Maline Creek E. coli TMDL ARAP
Project Name Plan/Phase Project Description Initial Design Commence - Complete
Construction
Ashbrook I/I Reduction
(Ashbrook Dr and Chambers Rd)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2016 2/17/2019 - 8/10/2020
Public I/I Rehabilitate 28,000 feet of the public sewer system using the cured in place pipe method. 8/5/2014 4/19/2016 - 6/14/2018
Private I/I
Construct 680 feet of 10-inch sanitary sewer, 75 feet of 12-inch storm sewer,
and remove Private I/I sources from sanitary sewers. 8/5/2014 4/18/2017 - 7/3/2017
Bellefontaine #2 Lateral Sanitary Relief (BP -287)
(Coburg Lands Dr)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 8/31/2014 - 5/22/2016
Public I/I Rehabilitation of the sanitary sewer system to reduce Public I/I. 8/22/2013 7/11/2014 - 6/6/2016
Private I/I Removal of 114 Private I/I sources from sanitary sewers. 8/22/2013 5/13/2014 - 7/17/2014
Bellefontaine #2 Sanitary Relief (BP -287)
(Chambers Rd to Coburg Lands Dr)
Master Plan Public I/I reduction and sanitary sewer rehabilitation. 8/10/2018 1/26/2021 - 7/20/2022
Sanitary Relief Construct 3,340 feet of 12-inch sanitary sewer, and eliminate constructed SSO outfall BP-287. 8/17/2017 4/29/20 - 4/08/21
Bissell Hills Sanitary Rehab Phase III (Service Lateral
Connections) (Chambers Rd and Coburg Lands Dr)
Master Plan Public I/I reduction and sewer rehabilitation. 8/31/2018 8/15/2021 - 8/5/2023
Public I/I Rehabilitate 26,000 feet of the public sewer system using the cured in place pipe method. 8/22/2018 12/16/2019 - 2/17/2021
Bissell Hills Sanitary Relief/St. Cyr Rd to Leeton Ave Master Plan Sanitary Relief 5/11/2019 10/27/2021 - 7/19/2023
Sanitary Relief Relief project not needed after post-construction monitoring. -- --
Bissell Hills Sanitary Relief/Calumet I/I Reduction
(BP-317)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 3/3/2015 - 2/20/2017
Public I/I Rehabilitation of the sanitary sewer system to reduce Public I/I. 8/22/2013 7/11/2014 - 6/6/2016
Private I/I Removal of Private I/I sources from sanitary sewers. 10/11/2012 2/17/2015 - 10/7/2015
Private I/I Removal of Private I/I sources from sanitary sewers. 10/11/2012 5/13/2016 - 8/1/2016
Calumet Dr Sanitary Relief
(Leeton Ave to Chambers Rd)
Master Plan Sanitary Relief 10/11/2024 3/30/2027 - 12/19/2028
Sanitary Relief Construct 4,600 feet of 18-inch to 21-inch sanitary sewer. 9/1/2024 3/01/2027 - 11/30/2028
Carson Villa I/I Reduction
(Marcella Ave and Wales Ave)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2017 2/17/2020 - 2/11/2021
Public I/I
Rehabilitate 26,000 feet of the public sewer system using
the cured in place pipe method. 8/22/2018 12/16/2019 - 2/17/2021
Private I/I
Construct 3,200 feet of 12-inch to 15-inch storm sewer,
and perform Private I/I reduction at 104 properties. 8/17/2017 6/12/2020 - 7/01/2021
Dacey Branch I/I Reduction (BP-313)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 3/22/2015 - 9/12-2016
Public I/I Rehabilitation of 48,670 feet of the public sewer system to reduce public I/I. 10/11/2012 10/1/2013 - 11/20/2015
Private I/I Removal of Private I/I sources from sanitary sewers. 10/11/2012 3/13/2014 - 5/2/2014
Private I/I Construct public storm sewer and disconnect downspouts and driveway drains. 2/5/2014 12/14/2015 - 4/4/2016
Dacey Branch Sanitary Relief
(Bella Clare Dr to Prior Dr)
Master Plan Sanitary Relief 12/1/2018 5/19/2021 - 11/10/2022
Sanitary Relief Construct 279 feet of 12-inch sanitary sewer and grade control structures. 8/22/2018 6/16/2021 - 12/18/2022
Dorothy Sanitary Relief
(Chambers Rd to McCartney Ln)
Master Plan Sanitary Relief 3/14/2030 8/30/2032 - 8/25/2033
Sanitary Relief
Construct 2,000 feet of 12-inch sanitary sewer. Contingency project to
eliminate constructed SSO outfall BP-317. 9/1/2029 8/13/2032 - 8/18/2033
Forestwood Lateral Sanitary Relief (SKME-321)
Master Plan Sanitary Relief Prior to 12/31/2013 08/31/14 - 8/20/2016
Sanitary Relief
Construct 6,700 feet of 12-inch to 24-inch sanitary relief sewer in the vicinity
of Forestwood, Highmont and Ferguson. Eliminate constructed SSO
outfalls BP-295, BP -296, bp-281, BP -316, and BP -322. 9/9/2004 1/7/2016 - 7/21/2017
Friedens (Partial) I/I Reduction
(Chain of Rocks Dr and Fontaine Pl)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2020 2/17/2023 - 2/12/2024
Public I/I
Rehabilitation of the public sewer system using the cured in place pipe method,
to reduce Public I/I. 9/1/2020 3/5/2022 - 3/15/2023
Private I/I
Construct 2,120 feet of 15-inch to 18-inch storm sewer, and perform
Private I/I reduction at 42 properties. 9/1/2020 6/17/2023 - 6/21/2024
MSD & MS4 Co-permittees Maline Creek E. coli TMDL ARAP
Project Name Plan/Phase Project Description Initial Design Commence - Complete
Construction
Kappel (Partial) I/I Reduction
(Exuma Dr and Glen Owen Dr)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2016 2/17/2019 - 2/12/2020
Public I/I Rehabilitate 56,000 feet of the public sewer system using the cured in place pipe method. 8/18/2015 11/18/2016 - 12/16/2018
Private I/I Remove Private I/I sources from sanitary sewers. 8/18/2015 6/9/2017 - 9/11/2017
Lang Royce Lateral Sanitary Relief (SKME-320)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 4/20/2015 - 4/9/2017
Public I/I Rehabilitation of 48,670 feet of the public sewer system to reduce Public I/I. 10/11/2012 10/1/2013 - 11/20/2015
Private I/I
Construct 2,000 feet of 10-inch to 12-inch sanitary sewer, and remove
Private I/I sources from sanitary sewers. 10/11/2012 11/14/2014 - 8/25/2015
Lang Royce Sanitary Relief
(Fargo Dr to Floridale Ct)
Master Plan Public I/I reduction and sewer rehabilitation 6/28/2019 12/14/2021 - 6/7/2023
Public I/I
Construct 1,000 feet of 8-inch to 15-inch sanitary sewer, and eliminate
constructed SSO outfall BP-291. 8/22/2018 6/01/2021 - 6/11/2022
Maline I/I Reduction & Sewer Rehabilitation (BP-
289) (Colony Dr)
Master Plan Public and Private I/I reduction and sewer rehabilitation Prior to 12/31/2013 9/15/2014 - 3/8/2016
Public I/I Rehabilitation of 48,670 feet of the public sewer system to reduce Public I/I. 10/11/2012 10/1/2013 - 11/20/2015
Private I/I Removal of Private I/I sources from sanitary sewers. 10/11/2012 5/13/2014 - 7/10/2014
Marietta Dr Storm Separation and I/I Reduction (BP-
292)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 4/3/2015 - 12/23/2016
Public I/I Rehabilitation of 48,670 feet of the public sewer system to reduce Public I/I. 10/11/2012 10/1/2013 - 11/20/2015
Private I/I
Construct 700 feet of 12 inch-30 inch storm sewer, and remove Private I/I sources from sanitary
sewers. Remove constructed SSO BP-292. 10/11/2012 3/13/2015 - 10/27/2016
Private I/I
Construct 700 feet of 12 inch-30 inch storm sewer, and remove
Private I/I sources from sanitary sewers. Remove constructed SSO BP-292. 10/11/2012 6/27/2016 - 10/27/2016
Marietta Sanitary Relief
(Circle Dr to Florissant Rd)
Master Plan Sanitary Relief 3/13/2019 8/29/2021 - 5/21/2023
Sanitary Relief Relief project not needed after post-construction monitoring. -- --
Mead Sanitary Relief
(Landwehr Ln to Hemlock Dr)
Master Plan Sanitary Relief 5/27/2018 11/12/2020 - 5/6/2022
Sanitary Relief Construct 213 feet of 12-inch sanitary sewer. 2/12/2018 8/20/2018 - 9/21/2018
Springdale I/I Reduction
(Rolling Dr and Smithfield Pl)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2016 2/17/2019 - 2/12/2020
Public I/I Rehabilitate 45,000 feet of the public sewer system using the cured in place pipe method. 8/18/2015 1/6/2017 - 12/24/2018
Private I/I Remove Private I/I sources from sanitary sewers. 8/18/2015 6/13/2017 - 10/30/2017
Suburban I/I Reduction
(Harrison Dr and Suburban Ave)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2016 2/17/2019 - 2/12/2020
Public I/I Rehabilitate 29,000 feet of public sewers using the cured-in-place pipe method. 8/5/2014 11/18/2016 - 11/19/2018
Private I/I
Construct 780 feet of 12-inch to 15-inch storm sewer, and remove
Private I/I sources from sanitary sewers. 8/5/2014 5/15/2017 - 11/21/2018
Sun Valley I/I Reduction
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 10/26/2014 - 1/19/2016
I/I Reduction
I/I reduction in the area of Halls Ferry Road south of St. Cyr road,
north to Maline Creek Trunk Sewer Section B. 3/22/2012 9/13/2013 - 6/13/2014
Thurston I/I Reduction
(Church St and N Florissant Rd)
Master Plan Public and Private I/I reduction and sewer rehabilitation. 8/31/2017 2/17/2020 - 2/11/2021
Public I/I Rehabilitate 26,000 feet of the public sewer system using the cured in place pipe method. 8/22/2018 12/16/2019 - 2/17/2021
Private I/I
Construct 3,200 feet of 12-inch to 15-inch storm sewer, and perform
Private I/I reduction at 104 properties. 8/17/2017 6/12/2020 - 7/01/2021
Upper Jeske Park Lateral Sanitary Relief (SKME-314)
Master Plan Public and Private I/I reduction and sewer rehabilitation. Prior to 12/31/2013 12/31/2013 - 10/21/2015
Public I/I Sewer lining and rehabilitation to reduce public I/I. 10/8/2009 5/14/2013 - 4/13/2015
Sanitary Relief Construct 2,300 feet of 12-inch to 18-inch diameter sanitary sewer and removal of Private I/I. 12/9/2010 9/13/2013 - 8/26/2014
MSD & MS4 Co-permittees Maline Creek E. coli TMDL ARAP
Project Name Plan/Phase Project Description Initial Design Commence - Complete
Construction
Upper Jeske Park Sanitary Relief
(Scott Dr to Cardigan Dr)
Master Plan Constructed SSO removal 1/8/2018 6/26/2020 - 12/18/2021
Const. SSO Removal Construct 2,300 feet of 12-inch to 18-inch diameter sanitary sewer and removal of Private I/I. 12/9/2010 9/13/2013 - 8/26/2014
Upper Maline Trunk Sanitary Relief
Phase IV Section A
Master Plan Sanitary Relief Prior to 12/31/2013 8/30/2014 - 5/17/2017
Sanitary Relief
Construct 7,300 feet of 42-inch to 48-inch sanitary sewer, including
pipe in tunnel. Eliminate constructed SSO outfall BP-305. 9/10/2009 3/11/2016 - 5/25/2018
Upper Maline Trunk Sanitary Relief
Phase IV Section B
Master Plan Sanitary relief 11/29/2015 11/13/2018 - 1/31/2021
Sanitary Relief
Construct 6,000 feet of 8-inch to 48-inch sanitary sewer, including pipe in tunnel. Eliminate
constructed SSO outfall BP-597. 9/10/2009 05/24/2018 - 11/30/2020
Upper Maline Trunk Sanitary Relief
Phase IV Section C
Master Plan Public I/I reduction and sewer rehabilitation. 4/26/2022 10/12/2024 - 7/4/2026
Public I/I Rehabilitate 20,000 feet of 8-inch to 42-inch sewer. 9/10/2009 12/16/2019 - 2/27/2021
* Status updates will be provided for each Master Plan project listed in Appendix A and submitted annually with the SWMP Annual report.
MSD & MS4 Co-permittees Maline Creek E. coli TMDL ARAP
Appendix B
Bacteria and Nutrient Best Management Practices Strategy Review
2009 East McCarty Street, Suite 1
Jefferson City, Missouri 65101
PH 573.443.4100
FAX 573.443.4140
www.geosyntec.com
Memorandum
Date: December 23, 2016
To: Jay Hoskins, Metropolitan St. Louis Sewer District
From: Avery Blackwell, P.E., Brandon Steets, P.E., Scott Struck, P.E., Dan
Pankani, P.E. Geosyntec Consultants
Eric Dove, David Carani, HDR
Subject: Bacteria and Nutrient Best Management Practice Strategy Review
Geosyntec Project: MOW5165E Phase 90
Attachments: Attachment A - BMP Evaluation Results
Recent actions by the Missouri Department of Natural Resources (MDNR) will impact how the
Metropolitan St. Louis Sewer District (MSD) administers their stormwater management
program. These actions include publication of the Missouri Nutrient Loss Reduction Strategy 1,
completion of Escherichia coli (E. coli or bacteria) total maximum daily loads (TMDLs) for four
streams in the St. Louis area 2, and renewal of the statewide small municipal separate storm sewer
system (MS4) general permit (MOR-040000). Central to each of these actions is the requirement
for MS4 programs to implement best management practices (BMPs) via an iterative process to
reduce the discharge of pollutants into the MS4 to the maximum extent practicable (MEP).
The purpose of this memo is to briefly outline these recent MDNR actions and potential MS4
program impacts, generally characterize MSD’s existing structural and non-structural BMPs for
bacteria and nutrients relative to the state of the practice and other MS4 programs, and
recommend actions that MSD could pursue to further identify areas to enhance BMP
implementation. The results of this review are intended to help MSD characterize MEP for
controlling bacteria and nutrients in stormwater runoff.
1 http://dnr.mo.gov/env/wpp/mnrsc/docs/nlrs-strategy-2014.pdf 2 TMDLs for Coldwater Creek, Creve Coeur Creek, Fishpot Creek, and Watkins Creek were approved by EPA on
July 13, 2016.
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REGULATORY CONTEXT
As mentioned above, the Missouri Nutrient Loss Reduction Strategy (Nutrient Strategy), recently
approved bacteria TMDLs, and the newly-issued small MS4 general permit each require MSD to
evaluate current approaches for defining MEP. Evaluating approaches for defining MEP for
controlling bacteria and nutrient levels in a comprehensive fashion will assist MSD in
determining how best to define MEP. A brief description of these MDNR initiatives and their
impact on MSD’s stormwater management program are outlined below.
In December 2014, MDNR finalized the Nutrient Strategy which outlines a set of recommended
actions that MS4s and other nutrient sources could implement to reduce nutrient loads to the
Gulf of Mexico. Available data (provided by MSD) suggest that MS4s are a relatively minor
source of nutrients to the Gulf and that additional data are needed to characterize urban
stormwater loads. The Nutrient Strategy also acknowledges the role of state-mandated funding
limitations for stormwater programs, and the need for an interactive, efficient, and cost-effective
approach to address MS4 nutrients. To that end, the Nutrient Strategy identifies several actions
that MS4 agencies should complete over a five-year period (2015-2019) to better characterize
their programs and define MEP in the context of nutrient reductions. These include the
following:
• From 2015 to 2017, review public involvement and education programs and material and
make recommendations for enhancements to implement in 2018-2019 consistent with
available funding.
• From 2015 to 2019, review programs and identify appropriate structural and non-
structural BMP enhancements to implement in 2020 and beyond consistent with available
funding. At a minimum, MS4 agencies should consider how low-impact development
practices might improve nutrient management effectiveness.
In January 2015, MDNR finalized E. coli TMDLs for four streams in the St. Louis area; EPA
subsequently approved the TMDLs in July of 2016. These TMDLs identified MSD and several
of the MS4 co-permittees as point source contributors of bacteria in the watersheds. As MDNR
stated in the “Reasonable Assurance” section of each TMDL, “The wasteload allocations for
MS4s will be implemented through the NPDES MS4 permits with the ultimate goal to employ an
iterative process using BMPs to the MEP, assessment, and refocused BMPs to the MEP, leading
toward attainment of water quality standards (64 FR 68753)”. In the implementation plan, which
accompanied each TMDL, MDNR discussed MS4 stormwater management plan requirements to
address the six minimum control measures (MCM), and reiterated that BMPs and programs
developed under the MCMs are expected to result in bacteria reductions from the MS4 area.
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Since 2013, MDNR has also been working closely with stakeholders, including MSD, to revise
and reissue the statewide Phase II MS4 general permit. The permit was issued by MDNR on
October 1, 2016. The permit includes clarifying language that MS4 discharge limits are defined
as BMPs to the MEP. More specifically, Section 1.4.1 of the permit states, “The permittee shall
implement Best Management Practices (BMPs) via an iterative process to reduce the discharge
of pollutants to the Maximum Extent Practicable (MEP) into the MS4 for the goal of attainment
with Missouri’s Water Quality Standards…” The permit also includes new requirements for MS4
that are subject to a TMDL. These requirements include developing a TMDL Assumptions and
Requirements Attainment Plan (ARAP) that includes, among other things, a process to identify
specific BMPs to address TMDL pollutants, prioritized actions, and an implementation schedule.
STRUCTURAL BACTERIA AND NUTRIENT BMP EVALUATION
Structural BMPs Evaluated
MSD requires new and redevelopment projects to submit a Stormwater Management Facilities
BMP Operation and Maintenance Design Report and Plan for approval. According to MSD’s
Small MS4 2015-16 Annual Report (Annual Report), since implementation of these new water
quality BMP requirements in October 2006, 1,286 projects representing 4,516 BMPs have been
constructed, permitted for construction, or are under review by MSD’s Planning Division.
According to the Annual Report, bioretention (48%) was by far the most common BMP
implemented (Figure 1).
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Figure 1. Post-Construction BMPs Built, Permitted for Construction, or Under Review as of 6/16/2016 (from the
Annual Report). Of the 4,516 BMPs, nearly half were bioretention
In addition to the structural BMPs identified in the Annual Report (Figure 1), this evaluation
included three common Post-Construction Ordinances: stream buffers, tree preservation, and
impervious area reduction. Also, two advanced structural BMPs designed specifically for
treating bacteria and nutrients were evaluated. These advanced structural BMPs included
enhanced biofilters 3 and subsurface flow wetlands 4.
3 Enhanced biofilters are defined here as vegetated media filters (or bioretention with underdrains) that incorporate
the following design enhancements that have been shown to improve bacteria reduction relative to standard
biofilters:
• Media amendments such as biochar and coconut coir that have been shown to enhance bacteria removal;
• Vegetation that is shown to enhance bacteria removal and support media aeration while reducing potential for
short circuiting or underdrain clogging;
• Outlet control for enhanced contact time; and
• A saturated zone. 4 Subsurface flow wetlands are engineered, below-ground horizontal flow treatment wetlands that include many of
the natural treatment processes of surface flow constructed wetlands as well as the filtration mechanisms of media
filters. Water flows through a granular matrix, which typically supports the growth of emergent wetland vegetation
on the surface.
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Relative Benefit Rankings for Structural BMPs
To evaluate bacteria and nutrient reduction effectiveness of ongoing structural BMP
implementation, the BMP categories were compared using a relative scoring system based on
weighting factors derived from previous BMP implementation planning experience, along with
feedback from MSD. Table 1 identifies the weighting applied to each benefit category and
briefly describes the approach to score the BMPs.
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Table 1. Approach for Scoring and Weighting Benefits.
Benefit
Group Benefit Category Weighting Scoring Approach
Target
Pollutant
Benefits
E. Coli Treatment 30% First, benefits from pollutant concentration reductions will
be calculated based on median effluent concentrations from
the International Stormwater BMP database5, along with
statistical results showing whether the removal was
significant (e.g. non-parametric hypothesis tests, either the
Mann-Whitney rank sum test or the Wilcoxon signed-rank
test). Then these scores will be modified to include the
pollutant reductions resulting from volume reduction.
Nitrite (NO2) and
Nitrate (NO3)
Nitrogen
Treatment
15%
Total Phosphorus
Treatment 15%
Additional
Benefits
Other Water
Quality Parameter
Treatment
15%
Based on significant reduction of other important water
quality parameters (e.g., total suspended solids, metals,
chloride) as reported in the Boston BMP Guidance
Document 6.
Flood
Management 10%
The relative ability to decrease flood risk by reducing peak
flow rates and/or volume reduction based on the Boston
BMP Guidance Document.
Habitat/
Environmental
Improvements
7%
Improvement and protection of wetland and riparian
enhancement/ creation evaluated by best professional
judgment.
Community
Enhancements 8%
Based on three factors: (1) Enhancement/creation of
recreational and public use areas, (2) Educational
opportunities, or (3) Aesthetic benefits evaluated by best
professional judgment.
Since the focus of this memorandum is evaluating BMP selection based on water quality
performance for bacteria and nutrients, benefits associated with the treatment of those target
pollutants were grouped and assigned the highest weighting factor. Because there are TMDLs
already in effect for bacteria in the St. Louis area, the E. coli weighting factor was higher than
the nutrients factor. The scoring of target pollutant benefits was performed quantitatively based
on the measured inflow and outflow concentrations for all BMPs that met data quality and
5 Geosyntec Consultants, Inc., Wright Water Engineers, Inc., International Stormwater BMP Database,
Manufactured Devices Performance Summary Report. July 2012. and International Stormwater Best Management
Practices (BMP) Database Pollutant Category Statistical Summary Report Solids, Bacteria, Nutrients, and Metals
http://www.bmpdatabase.org/ 6 Boston Water and Sewer Commission, Stormwater Best Management Practices: Guidance Document, prepared by
Geosyntec Consultants. January 2013.
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quantity criteria 7 from the International Stormwater BMP Database5. The scoring guidance for
the target pollutants is defined in Table 2. The analysis of the target pollutant benefits and the
benefit score for each post-construction structural BMP/Target Pollutant combination8 is
reported in Table A-1.
Table 2. Target Pollutant Benefit Scoring Guidance for Water Quality Benefits for BMPs.
Score Target Pollutant Benefit
3 High pollutant removal
2 Medium pollutant removal
1 Low or no pollutant removal
In addition to treating stormwater for the target pollutants, the BMPs were evaluated for other
benefits (Table A-2). These other benefits included: 1) reduction of other important water quality
parameters (e.g., TSS/sediments and metals), 2) ability to decrease flood risk by reducing peak
flow rates and/or volume reduction, 3) improvement and protection of wetland and riparian
enhancement/creation, and 4) community enhancements and opportunities. The weighting
factors for these additional benefits reflect their relative significance to MSD, while still
recognizing the important benefits that they could provide. The scoring of the additional benefits
was performed qualitatively based on the Boston BMP Guidance Document and best
professional judgment as defined in Table 3. The analysis of the additional benefits and the
benefit score for each BMP/additional benefit combination is reported in Table A-2.
7 To be included in this category-level summary, at least three BMP studies must be included in the BMP category,
with each BMP study having influent and effluent data for at least three storms for the pollutant of interest. 8 Post-construction ordinances and advanced structural BMPs do not have reported effluent concentrations in the
International Stormwater BMP database and therefore were not included in the Table A-1 analysis.
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Table 3. Scoring Guidance for Additional Benefits of BMPs.
Score Other Water
Qualitya Flood Management Habitat/
Environmental Communityb
3
High in both
sediment and
metals reduction
High volume and
peak flow reduction
Significant
portion of BMP
creates habitat
BMP provides high potential
for all two to three
community benefits
2
Medium sediment
and metals
reduction
Medium volume and
peak flow reduction
Some portion of
BMP creates
habitat
BMP provides medium
potential for two community
benefits
1
Low or no
sediment and
metals reduction
Low or no volume
and peak flow
reduction
Small amount or
no of habitat
created
BMP provides low or no
potential for two community
benefits
a. Chloride was also considered for evaluation in the “Other Water Quality” category; however, only
limited performance data exists for chloride and little or negative removal is shown for those BMPs
with data. Therefore, chloride was excluded in the scoring. b. Community benefits include enhancement/creation of public use areas; educational opportunities;
and community aesthetics.
Scores for each benefit category, as described above, were multiplied by their weighting factors
(Table 1) and a combined benefit score for each BMP 9 was calculated and reported in Table A-3.
The BMPs were then ranked according to their scores and the results are summarized in Table 4.
9 This table also includes scores for target pollutant benefits for post-construction ordinances and advanced
structural BMPs based on expected performance relative to similar BMP types determined using best professional
judgment.
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Table 4. Distribution of BMPs Used within the MSD Service Area and Benefits Ranking.
Rank BMP Score
% of BMPs
Built or
Planned
1 Infiltration BMPs 2.9 1%
2 Subsurface Flow Wetlands 2.8 NA
3 Ponds 2.6 1%
4 Enhanced Biofilters 2.5 NA
5 Bioretention 2.4 48%
5 Permeable Pavement 2.0 18%
7 Surface Sand Filters 1.8 0.04
8 Underground Sand Filters 1.8 1%
9 Underground Manufactured Filters 1.5 0.01
10 HDS Units 1.5 6%
11 Cisterns 1.4 0.01
12 Impervious Area Reduction 1.4 NA
13 Engineered Swales 1.3 4%
14 Tree Preservation Ordinance 1.2 NA
14 Stream Buffer 1.2 NA
Relative Cost Rankings for Structural BMPs
To provide estimates of the local capital and annual maintenance costs of the post-construction
structural BMPs and evaluate the relative cost ranking for the post-construction structural BMPs
and ordinances and advanced structural BMPs, the following cost analysis was conducted. The
cost estimations presented in this section are based on estimates of probable capital and
maintenance costs per capture (treatment) of runoff from one acre of drainage area. The costs
were computed by developing a cost estimation procedure that uses unit cost information from
literature for capital and maintenance costs to create curves (cost per volume treated translated
into cost per tributary area treated) for stormwater BMPs. Example unit cost items include:
• Mobilization
• Demolition
• Clearing & Grubbing
• Dewatering
• Excavation
• Haul/Dispose of Excavation Material
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• Rough and Finished Grading
• Pipe Material (primarily underdrain)
• Soil Media / Planting Media
• Other Bulk Material (pea gravel,
clean-washed gravel, base course
gravel and bedding material)
• Pavement/Concrete/Curbs
• Mulch
• Vegetation
Because there are many factors that affect the capital costs of structural BMPs besides the
treatment volume, such as development type (new development, redevelopment, retrofit), native
soil infiltration rate, site slope, pretreatment requirements, existing infrastructure, and large
event/overflow safety, a range of costs is included as part of the cost estimation. While the costs
for the effort were calculated on a national scale using literature and bid tabs from across the
country, an approach was developed using Bureau of Labor Statistics data for stormwater
construction equipment, material and labor to tailor estimated costs to the St. Louis region. Other
factors that can often influence costs such as: land acquisition, project purpose (e.g.,
demonstration project), regulatory and permitting requirements, utility conflict resolution,
design, union/non-union rates, and level of experience of designers and contractors were not
included as a part of the cost estimation. The three-step cost estimation approach is briefly
summarized below as follows:
• Step 1: Size BMPs – assume a 1-acre drainage area and use the 1.14-inch design storm
for the study area to compute the design volume of runoff required for each BMP for a 1-
acre residential (typically low estimate because of lower impervious surface density) and
1-acre commercial lot (typically higher estimate because of greater impervious surface
density requiring a larger treatment volume and therefor larger treatment facility).
• Step 2: Apply Cost Curve –determine cost curves function for each scenario and obtain
low/high cost estimation range for BMPs to meet design requirements. Report cost
estimate as a range comprised of the low residential estimate (assumed to be 35% site
imperviousness) and the high commercial estimate (assumed to be 65% site
imperviousness) to effectively bracket costs. Of note, if impervious density is greater,
than a higher cost would be needed to capture and treat the associated design volume.
• Step 3: Apply Cost Regionalization and Inflation Adjustment – Convert national
itemized unit cost estimates from RS Means, built projects, bid tabs, and other data
sources, using stormwater construction specific regional cost adjustment factor based on
Bureau of Labor Statistics data for St. Louis from Step 1. An inflation adjustment factor
was applied as needed to obtain 2015 estimates (the most recent complete year for
Bureau of Labor Statistics data).
The result of applying the three-step cost estimation approach is shown in Table 5.
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Table 5 Estimates of Probable BMP Construction and Maintenance Costs per Acre of Drainage Area Treated.
Post-Construction BMPS
Initial Capital Cost Estimate
Range*
(Treatment for a 1-acre site)
Annual Maintenance Cost
Estimate Range
(Per System)
Low High Low High
Bioretention $ 10,800 $ 25,400 $ 900 $ 4,000
Infiltration BMPs $ 4,800 $ 29,000 $ 700 $ 4,400
Engineered Swales $ 3,500 $ 17,600 $ 200 $ 1,300
Permeable Pavement $ 8,200 $ 27,600 $ 800 $ 3,100
Cisterns $ 12,400 $ 21,600 $ 200 $ 700
Ponds $ 9,000 $ 30,800 $ 700 $ 4,900
Surface Sand Filters $ 14,400 $ 38,800 $ 900 $ 3,200
Underground Sand Filters $ 17,000 $ 50,200 $ 1000 $ 3,700
Underground Manufactured
Filters $ 12,200 $ 39,300 $ 1,100 $ 4,600
HDS Units $ 14,100 $ 42,200 $ 1,000 $ 3,700
*Cost curves are not on a per acre basis as many costs are necessary for the first unit of BMP.
Subsequent/additional costs may not be linear and may not have a one to one relationship with area.
Approximate volume of treatment for the 1-acre site was about 1,450-2,700 ft3. Sizing for cost
estimation is based on an assumed volumetric capture (about one inch) but does not include achieving a
required level of performance.
To rank the structural BMPs, the average capital and maintenance costs were computed and
BMPs were ranked and placed into tiers representing similar costs between BMPs. The relative
capital cost and maintenance scores for each BMP were assessed for an estimated 20-year life
cycle cost to capture the long-term maintenance cost estimates along with initial capital costs.
The BMPs were then ranked according to their scores. The results are summarized in Table 6.
A lack of data on post-construction ordinances and the advanced structural BMPs resulted in
these management strategies receiving no cost score to prevent comparison and potential biases
between BMPs of known and unknown costs.
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Table 6 Rankings Based on Estimates of Probable Capital and Maintenance Costs
Tier BMP
Estimated Cost
Score
1
Engineered Swales 3.0
Cisterns 2.5
Bioretention 2.4
Infiltration BMPs 2.4
Ponds 2.3
Permeable Pavement 2.2
2
Underground Manufactured
Filters 1.6
Surface Sand Filters 1.6
HDS Units 1.4
Underground Sand Filters 1.0
3
Stream Buffer NA
Tree Preservation Ordinance NA
Impervious Area Reduction NA
Enhanced Biofilters NA
Subsurface Flow Wetlands NA
Not applicable (NA) was assigned to BMPs that did not have available cost
information.
Site-Specific Considerations for Using Structural BMP Rankings
An important component of post-construction runoff control programs, relative to the iterative
process of removing pollutants to the MEP, is the process for accounting for site-specific
feasibility issues and constraints. This issue is typically addressed in BMP technical guidance
manuals for new and redevelopment (and possibly in stormwater ordinances as well), and each
MS4 permittee or jurisdiction may choose to exercise their authority and level of
prescriptiveness differently. As one example, the Orange County Technical Guidance
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Document 10 establishes detailed infeasibility criteria for each BMP type. Below are some very
basic infeasibility criteria examples and their implications for BMP suitability relative to the
BMP ranking established herein:
• Infiltration constraints (e.g., tight soils and shallow bedrock or groundwater that would
prohibit infiltration based options) – At sites where such constraints exist, ponds,
subsurface flow wetlands, and enhanced biofilters are treatment-only BMPs that are
acceptable alternatives based on demonstrated pollutant removal performance.
• Limited space for BMP footprint (e.g., steep slopes within the site) – In this case,
permeable pavement is an acceptable and effective option to retain/treat stormwater
where the BMP area is incorporated into the development footprint. Also, enhanced
biofilters typically have a larger treatment capacity (i.e., can be built smaller, while still
treating the same design flowrate or volume) than similarly sized, higher ranked BMPs.
• Large design volumes requiring treatment (e.g., significant impervious area within the
site) – This constraint could make some BMP types infeasible unless implemented in
combination with others (e.g., large cisterns may be impractical). In general, project
applicants should be encouraged to consider the benefits of BMP combinations (e.g.,
treatment trains, distributed BMPs), where appropriate.
Finally, and related to both MEP and necessary components of any BMP technical guidance
manual, since this BMP ranking evaluation assumed all BMP types are sized the same, clear
design storm guidance should accompany any BMP selection guidance that is provided to project
applicants.
NON-STRUCTURAL BACTERIA AND NUTRIENT BMP EVALUATION
To better understand the extent to which non-structural BMPs are currently being implemented
to target bacteria and nutrients, stormwater program managers from MSD and seven other MS4
communities were surveyed. These communities were selected based on their geographic
distribution and ease of obtaining information. Furthermore, although MSD is a Phase II MS4,
both Phase I and II communities were included in the survey. Both Phase I (large) and II (small)
systems were surveyed since MSD’s stormwater system is more comparable in size to Phase I
communities; however, it is controlled under Phase II regulations and permit requirements. The
number of MS4 communities surveyed in each EPA region included:
10 County of Orange, 2013. Technical Guidance Document (TGD) for the Preparation of Conceptual/Preliminary
and/or Project Water Quality Management Plans (WQMPs). December 20, 2013.
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• MSD (EPA Region 7 – Phase II Community)
• EPA Region 7 – Phase I Community (2)
• EPA Region 7 – Phase II Community (1)
• EPA Region 4 – Phase I Community (1)
• EPA Region 4 – Phase II Community (1)
• EPA Region 5 – Phase II Community (2)
Program managers were presented with a list of potential bacteria and nutrient BMPs that could
be implemented under each of the six MCMs required by Phase II MS4 regulations. These BMPs
were developed from suggestions presented in the literature 11 and best professional judgment
(see Table A-5 for the list of BMPs). Program managers were asked to identify BMPs from the
list that are currently being applied within their system. It should be noted that the list of BMPs
was not intended to be all-encompassing. Rather, it reflects those BMPs most commonly
considered to be effective for managing bacteria and nutrients
For those BMPs being applied, the managers were then asked to qualitatively assess the degree
to which each is implemented using the following categories:
• High (green) – BMP is used with active management, measurement, or tracking.
• Medium (yellow) – BMP implemented but with limited measurement or tracking
measurement.
• Low (red) – BMP implemented intermittently but few to no measurements or tracking.
• None (blank) – BMP unused or unknown.
To assist in making meaningful comparisons between the qualitative assessment results, each
community response was converted to a relative score (high = 3, medium = 2, low = 1, none =
0). Converted response scores were then summed and standardized for each BMP category to
develop a normalized implementation score that ranges from 0 to 1. The normalized
implementation scores serve to represent the degree to which each BMP is implemented across
the surveyed communities. For a given BMP category, values near 0 indicate that few of the
surveyed communities use the BMP with limited implementation; values near 1 indicate that
most surveyed communities use the BMP with active implementation. For this evaluation,
normalized community scores were interpreted using the following scale:
11 Urban Water Resources Research Council (UWRRC). 2014. Pathogens in Urban Stormwater Systems.
Environmental and Water Resources Institute. American Society of Civil Engineers.
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• Less than or equal to 0.4 – Limited implementation. The BMP may not be applicable to
or appropriate for many communities. MSD should generally consider them to be low
priority BMPs.
• Between 0.4 and 0.6 – Moderate implementation. The BMP is commonly used and
should be considered for MSD’s program, if applicable.
• Greater than 0.6 – High implementation. The BMP is commonly used in most
communities. MSD should generally consider these to be high priority BMPs and identify
opportunities to include within the stormwater program.
Results of the evaluation show that the implementation of non-structural bacteria and nutrient
BMPs varies between MCMs and across the surveyed communities (Figure 2). In general, BMPs
under MCMs #1 (public education and outreach) and #6 (pollution prevention and good
housekeeping) have limited implementation, with several BMPs scoring between 0 and 0.4 for
all of the communities. The primary exceptions to this limited implementation are pet waste and
fertilizer outreach programs under MCM #1. In contrast, many BMPs under MCMs #3 (illicit
discharge detection and elimination) and #5 (post-construction stormwater management) have
scores between 0.6 and 1, indicating that these BMPs are generally implemented actively by all
of the communities. Results from MCM #2 (public involvement and participation) suggest that
most BMPs are consistently but moderately implemented by the communities (scores of 0.4 to
0.6).
The community survey scores were compared to those from MSD’s program to evaluate the
District’s current progress relative to other established programs and identify potential areas for
future enhancement. An overview of results for MSD’s stormwater program relative to the
surveyed communities for each MCM is included below. An overview of results for MSD’s
program relative to the surveyed communities for each MCM is included below.
• MCM #1 – Public Education and Outreach: Most BMPs are implemented to a limited
degree (score of less than 0.4) across the surveyed communities. Similarly, MSD does not
use many of the BMPs that were reviewed. With the exception of fertilizer outreach
efforts, BMPs that MSD does apply are implemented more actively relative to the other
MS4s.
• MCM #2 – Public Involvement and Participation: With the exception of downspout
disconnection and site designs (BMP 2.7), BMPs under this MCM are at least moderately
implemented across the communities. MSD implements most of the BMPs to a
comparable or greater degree than the other communities.
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• MCM #3 – Illicit Discharge Detection and Elimination: In general, these BMPs are
highly implemented across the communities. MSD implements a majority of BMPs under
this MCM to a comparable or greater degree than the other communities.
• MCM #4 – Construction Site Stormwater Runoff Control: MSD’s implementation of
the two BMPs reviewed under this MCM are generally comparable to the other
communities.
• MCM #5 – Post-Construction Stormwater Management: BMPs under this MCM are
actively implemented across the communities. MSD implements a majority of BMPs to a
comparable or greater degree than the other communities.
• MCM #6 – Pollution Prevention and Good Housekeeping: Implementation of BMPs
under this MCM was mixed across the surveyed communities. The BMPs that MSD does
apply are generally implemented more actively relative to the other communities.
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Figure 2. Summary of Non-Structural Bacteria and Nutrient BMP MS4 Community Survey Results. Normalized
implementation scores were calculated based on the degree to which each BMP is implemented across the
surveyed communities. For a given result, values near 0 indicate that few communities use the BMP with limited
implementation; values near 1 indicate that most communities use the BMP with extensive implementation. For
BMP identification numbers, refer to the community survey results in Table A-5.
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As MSD investigates enhancements to their stormwater programs over time, program managers
should initially focus on evaluating high priority (scores greater than 0.6) BMPs from the
community survey that are either not widely used or currently have limited implementation in the
St. Louis area. These include a using a public reporting tool (BMP 3.6), improving existing
septic system inventory activities (BMP 3.8), and increasing street sweeping frequency (BMP
6.8).
Once high priority BMPs have been addressed, MSD should review the moderately-implemented
(scores of 0.4 – 0.6) community survey BMPs to determine if they can be used or improved.
These BMPs include:
• Conducting private fertilizer education programs (BMP 1.3),
• Creating a tree sale program (BMP 2.2),
• Increasing the number and accessibility of public trash cans and pet waste stations (BMP
2.6),
• Improving baseflow source identification practices (BMP 3.1),
• Conducting instream algae monitoring (BMP 3.10),
• Improving construction site runoff control procedures on small sites (BMP 4.2), and
• Establishing a septic system elimination program (BMP 3.9).
MSD has recently worked to eliminate some septic systems in the St. Louis City and County area
as part of their Sewer Connection and Septic Tank Closure Program. Funding for this program
included a one-time allocation of approximately $2 million from MSD’s Project Clear. MSD and
their co-permittees should review the efficacy of the recent elimination program and determine
its viability as a permanent BMP going forward.
BMPs identified as having limited implementation in the community survey should be
considered a low priority for potential incorporation into MSD’s stormwater management
program. These BMPs should be reviewed over time as resources permit.
Other Considerations that Affect MEP for Non-Structural BMPs
While it is useful to understand MCM implementation by other MS4 communities across the
country to help establish what MEP is, MEP is also established in part by standard guidance. For
example, in ASCE’s Pathogens in Urban Stormwater Systems 12 report and presentations, it is
12 Urban Water Resources Research Council (UWRRC). 2014. Pathogens in Urban Stormwater Systems.
Environmental and Water Resources Institute. American Society of Civil Engineers.
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noted that non-structural BMP selection should be agency-specific (and thus not be designed to
precisely match the actions of other communities) and based on local sources. Local sources of
nutrients and bacteria should first be identified based on existing available GIS and monitoring
data, local knowledge and observations, and special studies. Then sources should be prioritized
based on risk level (e.g., human waste presents a greater illness risk than non-human and non-
fecal bacteria, certain forms of nutrients are more bioavailable or controlling in the
eutrophication process), and controllability. Once local sources are prioritized, then non-
structural source control BMPs should be selected to specifically target the highest priority
sources. This process, as documented through nationwide guidance, further helps to establish the
MEP.
An example process for bacteria is described here. Bacteria sources are typically ubiquitous in
the urban environment and numerous sources could contribute to excessive levels in urban
waterbodies. Therefore, a list of general urban sources and identification of non-structural BMPs
to address these typical sources would likely be too broad to develop a tailored non-structural
BMP program for each subwatershed or MS4 community. Guidance for identifying
subwatershed or MS4 community-specific bacteria sources can be found in the ASCE
publication, Pathogens in Urban Stormwater Systems, including:
• GIS mapping and analysis of infrastructure and analysis of monitoring data to identify
potential problem areas;
• Meeting with field staff and others with experience in the subwatershed to compile their
local knowledge;
• Subwatershed-specific observations;
• Enhanced illicit discharge detection and elimination (IDDE) investigations of MS4,
including microbial source tracking and traditional tools (e.g., CCTV and dye testing).
This source inventory could then be categorized and prioritized based on controllability and
public health risk, with human, non-human, and non-anthropogenic sources representing high,
medium, and low risk categories, respectively. Then non-structural BMPs could be selected to
effectively target the high and medium risk categories as comprehensively as possible and as
available funding allows. The ASCE pathogen publication provides examples of cost-effective
potential BMPs that may be considered based on the source identification findings, including:
• Sewer repairs where enhanced IDDE investigations have shown wastewater collection
systems leaking into the MS4
• Education/outreach to residential homeowners on limiting fertilizer application
• Improved prevention/housekeeping practices to limit fertilizer use by municipal
operations
• Pet waste disposal ordinances in areas of high pet density.
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Ultimately it may be more effective to aggressively implement a fewer number of BMPs that are
targeted to highest priority sources than to attempt to match the level of BMP implementation of
most other MS4 communities. For example, while resource intensive, septic inspection/inventory
and illicit connection detection are two of the most important BMPs for controlling human waste
and pathogens. MSD is implementing these BMPs at a “medium” or lower level. With increased
resources, efforts could be focused in high priority areas to better match the state of the practice
as documented in available nationwide guidance.
SUMMARY AND NEXT STEPS
Several new state regulatory requirements will impact how MSD administers their stormwater
management program. These new requirements will require MSD to evaluate and identify BMPs
that reduce bacteria and nutrients in stormwater runoff to the MEP. To assist MSD in
characterizing MEP for bacteria and nutrient, MSD’s existing structural and non-structural BMPs
were evaluated relative to the state of the practice and other MS4 programs. Significant findings
from this evaluation include the following:
• The top ranked structural BMPs (with a combined cost and benefit score above 4, as
shown in Table 7) were those that reduce runoff volume through infiltration or capture or
had advanced flow through designs. Few flow-through structural BMPs have effluent
concentrations that consistently meet water quality criteria for bacteria and nutrients
(only ponds).
• Approximately 70% of the built or planned structural BMPs in the MSD MS4 area are
ranked in the top three for benefits and have average scores (approximately 2) for costs.
• Post-construction ordinances and very basic structural BMPs were top ranked based on
costs, however these BMPs provided only minimal benefits.
• The treatment structural BMPs that incorporate advanced design characteristics (e.g.,
subsurface flow wetlands and enhanced biofilters) provide top ranked benefits, however,
their poor costs rankings can be prohibitive for some implementation scenarios.
• Site-specific feasibility issues and constraints can dramatically affect the performance
and costs of BMP types and should be considered early in the planning process.
• Going forward, MSD should focus on evaluating high priority (scores of greater than 0.6)
BMPs from the community survey that are either not widely used or currently have
limited implementation in the St. Louis area. Once high priority BMPs have been
addressed, MSD should review the moderately-implemented (scores between 0.4 and 0.6)
community survey BMPs to determine if they can be used or improved. Community
survey BMPs with limited implementation (scores less than 0.4) should be reviewed as
resources become available.
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• A comprehensive source identification and prioritization process directing the
implementation of non-structural BMPs can dramatically affect the effectiveness and
efficiency of the program.
Table 7 Benefits and Estimates of Probable Capital and Maintenance Costs
BMP
Estimated Benefits
Score
(Out of 3)
Estimated Cost
Score
(Out of 3)
Infiltration BMPs 2.9 2.4
Subsurface Flow Wetlands 2.8 NA
Ponds 2.6 2.3
Enhanced Biofilters 2.5 NA
Bioretention 2.4 2.4
Permeable Pavement 2.0 2.2
Surface Sand Filters 1.8 1.6
Underground Sand Filters 1.8 1
Underground Manufactured Filters 1.5 1.6
HDS Units 1.5 1.4
Cisterns 1.4 2.5
Impervious Area Reduction 1.4 NA
Engineered Swales 1.3 3.0
Stream Buffer 1.2 NA
Tree Preservation Ordinance 1.2 NA
Not applicable (NA) was assigned to BMPs that did not have available cost information.
Results of this evaluation can be used to help review the MSD BMP Toolbox
(http://www.stlmsd.com/what-we-do/stormwater-management/bmp-toolbox) and identify
potential areas to enhance BMP implementation. Some preliminary examples include:
• Highlighting the importance of implementing BMPs that focus on bacteria and nutrient
reduction.
• Providing guidance for the selection of BMPs capable of achieving bacteria and nutrient
reduction given site-specific conditions (e.g., land use, space constraints, rainfall patterns,
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etc.) or identified sources (e.g., residential and municipal over-fertilization, dumpsters,
washdown and grease traps at food outlets).
• Providing additional BMP design guidance related specifically to bacteria and nutrient
removal including:
o Vegetation selection
o Outlet controls/contact time guidance
o Media selection and specification
o Removal of compost/alternative soil amendments (a source of nutrients)
o Incorporation of saturated zone for bacteria and/or nitrogen removal
o Incorporation of an activated alumina layer for phosphorus removal
o Other pertinent design information based on findings from literature
*****
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ATTACHMENT A
BMP EVALUATION RESULTS
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Table A-1. Benefit Scores for Each Structural Best Management Practice (BMP)/Target Pollutant Combination
E. Coli Treatment Nitrite (NO2) + Nitrate (NO3) as
Nitrogen Treatmentd Total Phosphorus Treatment
Post-Construction Structural
BMPs BMP Database Category
Median Effluent
Concentration
(colonies /100ml)
Statistically
Significant
Removal (Y/N)
Score
Median
Effluent
Concentration
Statistically
Significant
Removal
(Y/N)
Score
Median
Effluent
Concentration
Statistically
Significant
Removal
(Y/N)
Score
(mg/L) (mg/L)
Bioretention Bioretention 101 Y 3 0.37 N 1 0.24 N 1
Infiltration BMPs Not Available Not Available 3 Not Available 3 Not Available 3
Engineered Swales Biofilter - Grass Swale 4,182 N 1 0.22 N 1 0.171 N 1
Permeable Pavement Porous Pavement Not Available 3 1.35 N 3 0.1 Y 3
Cisterns Not Available Not Available 1 Not Available 1 Not Available 1
Ponds Retention Pond 100 Y 3 0.13 Y 2 0.091 Y 2
Surface Sand Filters Media Filter 420a Y 2 0.57 N 1 0.089 Y 2
Underground Sand Filters Media Filter 420a Y 2 0.57 N 1 0.089 Y 2
Underground Manufactured
Filters Manufactured Device - Filtration 910b N 1 0.29c N 1 0.06 Y 2
HDS Units Manufactured Device - Physical 910b N 1 0.36c Y 2 0.22 Y 2
a. The International Stormwater BMP Database does not have sufficient data for Media Filter E. coli effluent concentrations; therefore, the reported fecal coliform was evaluated.
b. The BMP Database does not have sufficient data for Manufactured Devices (Filtration and Physical) E. coli effluent concentrations; therefore, the reported fecal coliform was evaluated.
c. The BMP Database does not have sufficient data for Manufactured Devices (Filtration and Physical) NO2 + NO3 as Nitrogen effluent concentrations; therefore, NOx as Nitrogen was evaluated.
d. NO2 + NO3 as Nitrogen was evaluated since it had the most results in the BMP Database.
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Table A-2. Additional Benefit Scores for Each BMP/Targeted Benefit Combination
Other Water Quality Treatment Flood Management Habitat / Environmental Community Enhancements
Post-Construction Structural BMPs Sediment
Reduction
Metals
Reduction Score Volume
Reductiona
Peak Flow
Reduction Score Habitat
Creation Score
Enhancement/
Creation of Public
Use Areas
Educational
Opportunities
Community
Aesthetics Score
Bioretention High High 3.0 High Medium 2.5 High 3.0 High High High 3.0
Infiltration BMPs High High 3.0 High High 3.0 Medium 2.0 Medium High Medium 2.3
Engineered Swales Medium Medium 2.0 Low Low 1.0 Medium 2.0 Medium Medium Medium 2.0
Permeable Pavement Medium Medium 2.0 Medium Medium 2.0 Low 1.0 Low Medium Low 1.3
Cisterns High Medium 2.5 High Medium 2.5 Low 1.0 Low Medium Medium 1.7
Ponds High High 3.0 Low High 2.0 High 3.0 High High High 3.0
Surface Sand Filters High High 3.0 Low Low 1.0 Low 1.0 Low Medium Low 1.3
Underground Sand Filters High High 3.0 Low Low 1.0 Low 1.0 Low Low Low 1.0
Underground Manufactured Filters High High 3.0 Low Low 1.0 Low 1.0 Low Low Low 1.0
HDS Units Medium Medium 2.0 Low Low 1.0 Low 1.0 Low Low Low 1.0
Post-Construction Ordinances
Stream Buffer Medium Medium 2.0 Low Medium 1.5 High 3.0 High Medium High 2.7
Tree Preservation Ordinance Low Low 1.0 Medium Low 1.5 High 3.0 High Medium High 2.7
Impervious Area Reduction Medium Medium 2.0 Medium Medium 2.0 Medium 2.0 High Low Medium 2.0
Advanced Structural BMPs
Enhanced Biofilters (e.g., Bioretention
with underdrains) High High 3.0 Medium Medium 2.0 High 3.0 Medium High High 2.7
Subsurface Flow Wetlands High High 3.0 Medium Medium 2.0 High 3.0 High High High 3.0
a. It is assumed that all the BMPs are sized to treat the same design storm (e.g., bypass from a flow through BMP such as engineered swales, sand filter, pond, etc. would be as frequent as from a retention BMP such as bioretention, infiltration
basin, etc.). For this reason, both bioretention and cisterns are assumed to have high volume reduction.
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Table A-3. Summary of Structural BMP/Benefit Scoring
Target Pollutant Benefitsa Additional Benefits
E. Coli
Total
Nitrogen
Total
Phosphorus
Other
Water
Quality
Flood
Management
Habitat/
Environmental
Community
Enhancements Total Score Rank
(out of 15)
Weighting 30% 15% 15% 15% 10% 7% 8% 100%
Post-Construction Structural
BMPsb
% of BMPs Built
or Planned 1-3 1-3 1-3 1-3 1-3 1-3 1-3 3
Bioretention 48% 3.0 1.0 1.0 3.0 2.5 3.0 3.0 2.4 5
Infiltration BMPs 1% 3.0 3.0 3.0 3.0 3.0 2.0 2.3 2.9 1
Engineered Swales 4% 1.0 1.0 1.0 2.0 1.0 2.0 2.0 1.3 13
Permeable Pavement 18% 3.0 1.0 2.0 2.0 2.0 1.0 1.3 2.0 6
Cisterns 1% 1.0 1.0 1.0 2.5 2.5 1.0 1.7 1.4 11
Ponds 1% 3.0 2.0 2.0 3.0 2.0 3.0 3.0 2.6 3
Surface Sand Filters 4% 2.0 1.0 2.0 3.0 1.0 1.0 1.3 1.8 7
Underground Sand Filters 1% 2.0 1.0 2.0 3.0 1.0 1.0 1.0 1.8 8
Underground Manufactured Filters 1% 1.0 1.0 2.0 3.0 1.0 1.0 1.0 1.5 9
HDS Units 6% 1.0 2.0 2.0 2.0 1.0 1.0 1.0 1.5 9
Total systems install on new or
redevelopment since 2006 4,516
Post-Construction Ordinances
Stream Buffer NA 1.0 1.0 1.0 2.0 1.0 3.0 3.0 1.2 15
Tree Preservation Ordinance NA 1.0 1.0 1.0 1.0 1.0 3.0 2.0 1.2 14
Impervious Area Reduction NA 1.0 1.0 1.0 2.0 2.0 2.0 2.0 1.4 12
Advanced Structural BMPs
Enhanced Biofilters NA 3.0 1.0 3.0 3.0 1.0 3.0 3.0 2.5 4
Subsurface Flow Wetlands NA 3.0 3.0 3.0 3.0 1.0 3.0 3.0 2.8 2
a. BMPs with high volume reduction (see the Flood Management category in Table A-2) have a target pollutant benefit of 5. For BMPs with medium volume reduction have 1 point added to each
target pollutant effluent concentration score
b. The permitted structural BMP "storm credits" and "other" are not included in the BMP scoring because of the variety of approaches used in each of those categories
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Table A-4. Summary of Structural BMP/Cost Scoring
Initial Capital Cost Estimate Rangea Annual Maintenance Cost Estimate Range Averaged
Score
(out of 3)
Rank
(out of 10) (Treatment for a 1-acre site) (Per System)
Post-Construction Structural
Controls Low High Average Low High Average
Bioretention $7,800 $25,400 $16,600 $4,000 $2,450 $19,050 2.4 3
Infiltration BMPs $4,800 $29,000 $16,900 $4,400 $2,550 $19,450 2.4 4
Engineered Swales $3,500 $18,700 $11,100 $1,300 $750 $11,850 3.0 1
Permeable Pavement $8,200 $27,600 $17,900 $3,100 $1,950 $19,850 2.3 5
Cisterns $12,400 $21,600 $17,000 $800 $500 $17,500 2.5 2
Ponds $9,000 $26,900 $17,950 $4,500 $2,600 $20,550 2.3 6
Surface Sand Filters $14,400 $38,800 $26,600 $3,200 $2,050 $28,650 1.6 8
Underground Sand Filters $16,200 $50,200 $33,200 $3,700 $2,350 $35,550 1.0 10
Underground Manufactured
Filters $12,200 $39,300 $25,750 $4,600 $2,850 $28,600 1.6 7
HDS Units $14,100 $42,200 $28,150 $3,700 $2,350 $30,500 1.4 9
Post-Construction Ordinancesb
Stream Buffer NA NA
Tree Preservation Ordinance NA NA
Impervious Area Reduction NA NA
Advanced Structural Controlsb
Enhanced Biofilters NA NA
Subsurface Flow Wetlands NA NA
a. Cost curves are not on a per acre basis as many costs are necessary for the first unit of BMP. Subsequent/additional costs may not be linear and may not have a one to one
relationship with area. Approximate volume of treatment for the 1-acre site was about 1450-2700 ft3. Sizing for cost estimation does not include achieving a required level
of performance.
b. Cost estimates were not available for post-construction ordinances or advanced structural BMPs, therefore relative costs were assigned using best professional judgment.
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Table A-5. Non-Structural Bacteria and Nutrient Best Management Practice (BMP) MS4 Community Survey Results.