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CREVE COEUR CREEK BACTERIA TMDL
ASSUMPTIONS AND REQUIREMENT
ATTAINMENT PLAN
June, 2019
Prepared by Metropolitan St. Louis Sewer District in coordination with its MS4 co-permittees.
MSD & MS4 Co-permittees
Creve Coeur Creek bacteria TMDL ARAP
TABLE OF CONTENTS
1.0 Introduction and Purpose ....................................................................................................................... 3
1.1 Creve Coeur Creek Bacteria TMDL ................................................................................................ 3
1.2 MS4 Permit Requirements ............................................................................................................... 5
2.0 E. coli Bacteria and its Potential Sources ........................................................................................ 6
2.1 Sanitary Sewer Infrastructure .......................................................................................................... 6
2.2 Individual Sewage Disposal Systems .............................................................................................. 8
2.3 Urban Stormwater Runoff ................................................................................................................ 9
2.4 Riparian Conditions ......................................................................................................................... 9
2.5 Illicit Straight Pipe Discharges ........................................................................................................ 9
3.0 TMDL Implementation Activities ....................................................................................................... 10
3.1 St. Louis County Phase II Stormwater Management Plan ............................................................. 10
3.1.1 MCM #1, Public Education and Outreach of Stormwater Impacts .................................. 10
3.1.2 MCM #2, Public Involvement and Participation .............................................................. 11
3.1.3 MCM #3, Illicit Discharge Detection and Elimination ..................................................... 12
3.1.4 MCM #4, Construction Site Stormwater Runoff Control ................................................. 13
3.1.5 MCM #5, Post-Construction Stormwater Management in
New Development and Redevelopment ............................................................................ 14
3.1.6 MCM #6, Pollution Prevention Good Housekeeping for Municipal Operations .............. 15
3.2 Project Clear .................................................................................................................................. 16
3.2.1 Sanitary Sewer Overflow Control Master Plan ..................................................................... 16
3.2.1.1 Sewer System Evaluation Survey (SSES) ................................................................... 16
3.2.1.2 Master Plan Projects .................................................................................................... 17
3.2.2 Capacity, Management, Operations, and Maintenance Program .......................................... 18
3.2.3 Fats, Oil, and Grease Program .............................................................................................. 19
3.3 TMDL Best Management Practices Targeting Bacteria ................................................................ 20
4.0 Evaluation ............................................................................................................................................ 23
LIST OF FIGURES
Figure 1. Creve Coeur Creek showing the impaired reach for the bacteria 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 Creve Coeur Creek. ........................ 5
Table 2. Summary of Sanitary Sewer Gravity Pipes by Pipe Diameter and Material in Creve Coeur
Creek Watershed as of February 11, 2019 ..................................................................................... 7
Table 3. Summary of Sanitary Sewer Pipes by Pipe Diameter and Material that have
Received Cured in Place Lining in Creve Coeur Creek Watershed as of February 11, 2019 ........ 7
Table 4. Summary of Capacity and Non-Capacity Overflows and
Bypasses for Creve Coeur Creek Watershed, 01/01/2016 - 12/31/2018 ....................................... 8
Table 5. TMDL Best Management Practices Targeting Bacteria in the
Creve Coeur Creek Watershed ..................................................................................................... 22
APPENDICES
Appendix A. SSO Control Master Plan Projects in the Creve Coeur Creek Watershed
Appendix B. Bacteria and Nutrient Best Management Practices Strategy Review
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1.0 Introduction and Purpose
Creve Coeur Creek first appeared on Missouri’s Section 303d list of impaired waters for elevated
concentrations of Escherichia coli (E. coli) bacteria in 2006. 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. Creve Coeur Creek remained on Missouri’s Section 303d list of impaired waters for
E. coli from 2006 to 2016. On July 13, 2016, the United States Environmental Protection Agency
(USEPA) approved Missouri’s bacteria Total Maximum Daily Load (TMDL) for Creve Coeur Creek1.
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 Creve Coeur Creek
bacteria 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 allocation assigned to the MS4 area in the Creve Coeur
Creek bacteria 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 bacteria
specific to the Creve Coeur 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 Creve Coeur Creek bacteria TMDL and TMDL
Implementation Plan2 were used in the development of this TMDL ARAP.
1.1 Creve Coeur Creek Bacteria TMDL
Creve Coeur Creek is located in west-central St. Louis County. Its most upstream extent occurs near the
intersection of Kehrs Mill Road and Clayton Road in Ballwin and it generally flows to the northeast for
nearly 11.9 miles before it reaches Creve Coeur Lake in Maryland Heights. From Creve Coeur Lake the
creek flows nearly 2.2 miles further to its confluence with the Missouri River. The watershed covers
approximately 27.6 square miles and contains karst geologic features such as sink holes. From Creve
Coeur Lake upstream 3.8 miles, Creve Coeur Creek (WBID 1703) is Class C water which 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. It is this portion of Creve Coeur
1 Missouri Department of Natural Resources Water Protection Program. 2016. Bacteria total maximum daily load (TMDL) for
Creve Coeur Creek, St. Louis County, Missouri. Completed: Dec. 31, 2014. Approved: July 13, 2016. 36pp. 2 Missouri Department of Natural Resources Water Protection Program. 2014. Bacteria total maximum daily load implementation
plan for Creve Coeur Creek Water Body ID No. 1703, St. Louis County. 26pp.
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Creek which has been listed as impaired for bacteria. Creve Coeur Creek is considered an urban stream
and its watershed includes portions of the following MSD co-permittees: Ballwin, Chesterfield, Creve
Coeur, Maryland Heights, Town and Country, and St. Louis County (unincorporated areas). The
watershed also includes a small portion of Country Life Acres, which is not a co-permittee.
Figure 1. Creve Coeur Creek showing the impaired reach for the bacteria 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:
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 Creve Coeur Creek bacteria TMDL was developed using a numeric target concentration of 206
counts/100mL and a load duration curve. The target concentration represents Missouri’s water quality
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criterion of 206 E. coli counts per 100mL of water. The load duration curve applied average daily
discharge data (cfs) between June 11, 1997 to Jan. 2, 2011 from the United States Geological Survey
(USGS) gage station USGS 06935890 located at Olive Boulevard in the northeastern extent of the City of
Chesterfield. Discharge data were corrected to account for a larger drainage area as delineated by the
outlet of the impaired reach of Creve Coeur Creek. 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 Creve Coeur 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 95
percent of the watershed. The second MS4 permit is held by the Missouri Department of Transportation
(Permit No. MO-R0400563) and covers the remaining five percent. There are no other permitted
facilities in Creve Coeur 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 bacteria TMDL for Creve Coeur Creek1.
Table 1. TMDL requirements for E. coli bacteria at specific flows in Creve Coeur Creek1.
Percentile Flow
Exceedance
Flow
(cfs)
TMDL
(counts/day)
MS4 WLA
(counts/day)
LA
(counts/day)
95 1.9 9.50E+09 9.50E+09 0
75 4.4 2.22E+10 2.22E+10 0
50 8.3 4.18E+10 4.18E+10 0
25 17.6 8.87E+10 8.87E+10 0
10 56.6 2.85E+11 2.85E+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 Creve Coeur Creek bacteria 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 value used the
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, 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:
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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 2006-2016 note the source of E. coli bacteria in
Creve Coeur Creek as urban nonpoint source pollution or urban runoff/storm sewers. The Creve Coeur
Creek bacteria 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 Creve Coeur Creek.
2.1 Sanitary Sewer Infrastructure
There are no permitted facilities that discharge domestic or municipal wastewater treatment systems in the
Creve Coeur Creek watershed. MSD’s Missouri River Wastewater Treatment Facility which receives
wastewater generated in the Creve Coeur Creek watershed is located about two miles to the north of the
watershed. Sanitary sewer infrastructure is present throughout the watershed however, comprising nearly
356.0 miles of pipe. A summary of public gravity fed 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.
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Table 2. Summary of Sanitary Sewer Gravity Pipes by Pipe Diameter and Material
In Creve Coeur Creek Watershed as of February 11, 2019.
Pipe
Diameter (inches) VCP Plastic RCP Cast Iron
or DIP Other Sub-Total
Length in Feet
6 5,385 3,999 -- 202 -- 9,586
8 747,433 860,385 15 19,489 667 1,627,989
10 22,858 24,742 85 1,590 -- 49,275
12 10,616 20,765 -- 1,627 124 33,132
15 5,119 28,174 -- 1,137 -- 34,430
16 -- 1,080 -- 3,203 -- 4,283
18 1,582 17,260 49 3,471 55 22,417
20 -- -- -- 163 -- 163
21 -- 4,274 -- -- -- 4,274
24 238 11,565 4,400 3,292 -- 19,494
27 -- 2,119 -- -- -- 2,119
30 -- 5,373 8,977 1,774 24 16,148
36 -- -- 12,621 1,479 -- 14,100
42 -- 236 5,292 1,378 -- 6,906
48 -- -- 7,829 307 2,064 10,200
60 -- -- 6,354 -- -- 6,354
66 -- -- 8,009 -- -- 8,009
72 -- -- 1,650 -- -- 1,650
96 -- -- 266 -- -- 266
Total 793,231 979,972 55,547 39,112 2,934 1,870,796
VCP is vitrified clay pipe; RCP is reinforced concrete pipe; DIP is ductile iron pipe.
Table 3. Summary of Sanitary Sewer Pipes by Pipe Diameter and Material that have
Received Cured-in-Place Lining in Creve Coeur Creek Watershed as of February 11, 2019.
Pipe
Diameter
(inches)
VCP Plastic RCP Cast
Iron DIP Other Sub-Total
Length in Feet
8 204,190 3,230 -- 643 1,699 984 210,746
10 15,491 -- -- -- -- -- 15,491
12 5,913 208 -- -- 112 -- 6,232
15 5,535 -- -- -- -- -- 5,535
24 -- -- 576 -- -- -- 576
30 -- -- 4,827 -- 347 -- 5,174
Total 231,129 3,438 5,403 643 2,158 984 243,755
VCP is vitrified clay pipe; RCP is reinforced concrete pipe; DIP is ductile iron pipe.
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In addition to sewer pipes, there are 9,958 sanitary manholes in the Creve Coeur Creek watershed that fall
under public or private ownership. Of those, 9,297 fall under MSD ownership. Manholes are mostly
constructed of precast sections of concrete, poured-in-place concrete, brick and other materials. There are
six sanitary pump stations located within the watershed boundary, and five more located outside that are
connected to forcemains within the watershed. Forcemains in the Creve Coeur Creek watershed total
approximately 1.7 miles.
Of the six constructed sanitary sewer overflow (SSO) points first described in the TMDL, there are
currently two that remain. Three constructed SSOs were eliminated by the time the TMDL was
completed, whereas BP-033 was eliminated on March 5, 2015, after the TMDL was completed. The two
remaining constructed SSOs, BP-036 and BP-037, are scheduled to be eliminated between 2019-2023 per
MSD’s Project Clear program.
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 in the Creve Coeur Creek watershed for the period of January 1, 2016 through
December 31, 2018 is provided in Table 4.
Table 4. Summary of Capacity and Non-Capacity Overflows and
Bypasses for Creve Coeur Creek Watershed, 01/01/2016 - 12/31/2018.
Cause Count Remedy
Debris Blockage 13 Cleaned/Cleared
Root Blockage 6 Cleaned/Cleared
Grease Blockage 3 Cleaned/Cleared
Broken Pipe 7 Repaired
Pump Station Power Outage 2 Power Restored
Total 31 --
As part of the SSO Master Plan requirement in MSD’s federal consent decree3, MSD conducted a Sewer
System Evaluation Survey (SSES) for the Creve Coeur Creek watershed. SSES findings related to sewer
defects and SSO Master Plan remedial projects are described in Section 3.2.1.1 of this ARAP and
Appendix A, respectively.
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. The Creve
Coeur bacteria TMDL referenced two sources of information focusing on failure rates of individual
sewage disposal systems. The first, EPA’s Spreadsheet Tool for Estimating Pollutant Load (STEPL),
estimates the failure rate in St. Louis County as being 39 percent based upon census data from the 1990s.
The second, a study conducted by the Electric Power Research Institute suggests that up to 50 percent of
the systems in Missouri may be failing.
In a more 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 home4. When residents were asked if their septic system had
3 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.
4 ETC Institute for Metropolitan St. Louis Sewer District. 2017. Metropolitan St. Louis Sewer District environmental awareness
survey. ETC Institute. 47pp.
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been serviced in the last five years, 64% (14) of those indicated it had, 14% (3) said it had not, and 23%
(5) were unsure. Of 18 residents asked about the age of their system, 28% (5) said their septic system was
more than 30 years old. As referenced in the Creve Coeur Creek bacteria TMDL, there are approximately
223 parcels in the watershed suspected of not having a connection to the public sewer. 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 Creve Coeur Creek watershed is not entirely known.
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 Creve Coeur Creek. According to a study conducted by USGS5 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 geese5. Note, this USGS5 study included data collected from a single sample site in Creve
Coeur Creek.
Urban runoff discharges from the two MS4 permitted systems are considered potential point sources of E.
coli to Creve Coeur 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 Creve Coeur Creek bacteria TMDL.
2.4 Riparian Conditions
Riparian conditions in the watershed were listed in the Creve Coeur Creek bacteria TMDL as a likely
source of bacteria. The riparian corridor of streams in the Creve Coeur Creek watershed, extending 30-
meters on each side of the channel, is predominantly urban and forested. Notably, 38 percent is low-
intensity urban, 32 percent is forest and woodland, nearly 14 percent grassland, and approximately 2
percent is impervious1. Low-intensity urban land cover includes residential areas where bacteria loading
from pet and wildlife waste can be picked up by stormwater runoff. Similarly, stormwater runoff from
grassland cover in an urban setting may also contribute bacteria to Creve Coeur Creek if it comes in
contact with pet and wildlife waste.
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. Per the Creve Coeur Creek bacteria TMDL, due to
the presence of a sewerage system throughout the 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
5 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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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 Creve
Coeur 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
Management Plan (Third Term Permit 2017-2021) and Project Clear which addresses 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
Creve Coeur 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 Creve Coeur
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 implementation6. 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
6 The SWMP is available on MSD’s website, www.stlmsd.com.
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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.
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
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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.
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 Creve Coeur 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.
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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.
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,
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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.
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 site design guidance 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.
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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).
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:
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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.
3.2 Project Clear
MSD’s implementation of Project Clear has and will continue to result in reduced bacteria loading to
Creve Coeur 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, 20337. 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 Creve Coeur 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 completed 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 Creve Coeur Creek watershed8.
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)
7 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.
8 Metropolitan St. Louis Sewer District. 2013. Creve Coeur Creek watershed sewer system evaluation survey. Completed
December 31, 2013. 444pp.
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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 33 I/I study areas in Creve Coeur Creek watershed. Study areas were ranked and
prioritized by the existence of constructed SSOs, number of insurance claims, number of service requests,
water quality impacts, and I/I estimates from models. Higher priority study areas, those with excessive I/I
causing or contributing to SSOs or building backups, generally occurred in the southwest and
northeastern extents of the watershed; whereas central and north central areas of the watershed generally
did not meet high priority ranking requirements. In total, 16 areas were ranked as high priority and
investigated for I/I sources contributing to SSOs and building backups.
Based on the age of housing and building information, some of the sanitary sewers in the watershed were
built in the early 20th century, while most were constructed after 1965. The majority of sanitary sewers
constructed prior to 1940 or from 1941-1965 are located east of Highway 141. Sanitary sewers built from
1965-1985 and 1986-2010 are dispersed throughout Creve Coeur Creek watershed. Vitrified clay and
plastic were the two most common materials used for pipe construction. Recently obtained pipe material
data is shown in Tables 2 and 3 of this report.
Physical/structural condition and design constraints of sanitary sewer infrastructure were described in the
SSES report. At the time of the SSES report, there were 12 pump stations in the watershed owned by
MSD, one pump station did not have backup storage capacity or onsite backup power, and two had
reached or exceeded their design life. There were no design constraints associated with any of the force
mains. CCTV investigations of 1,849 sewer reaches, comprising 19% 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 30% had major or moderate structural issues or root
intrusion, and were classified in the “strong” or “medium” attention level.
Studies conducted in higher priority areas of the watershed attributed I/I sources 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 no direct connections among the public defect findings. Private sources of I/I were
the result of connected downspouts, and defective 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 manhole frames, defective cleanouts, and defective
manhole structures. Defect categories that may have the greatest impact on wet weather flows (average
flow per defect) associated with the overall I/I included connected downspouts, indirect connections, and
plumbing inside buildings. The SSES report for the Creve Coeur 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, 18 SSO Control Master Plan projects were originally scheduled in the Creve
Coeur Creek watershed. Appendix A includes a table with all SSO Control Master Plan projects for
Creve Coeur Creek watershed. Projects listed in the table include schedules for the Master Plan projects
as well as schedules for their respective public portions. Public and private work includes remedial
measures to address their respective defects as described in the previous section and SSES report. All
work is routinely scheduled ahead of Master Plan dates to ensure compliance with timelines in MSD’s
consent decree.
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Four projects in the SSO Control Master Plan for the Creve Coeur 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.
Fourteen 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. Creve Coeur Creek (L-52) Force Main Improvements
Phase II increased the capacity of the force main; therefore this project is grouped with other public
sanitary relief projects.
Of the 18 SSO Control Master Plan Projects, six have already been completed and are in service. Projects
that have been completed include the following:
• CC-14 Creve Coeur Creek Sanitary Relief (SKME-026) Phase II;
• CC-17 Four Seasons Branch Sanitary Relief;
• Creve Coeur Creek (L-52) Force Main Improvements Phase II;
• Creve Coeur Creek Watershed Sanitary Sewer Rehabilitation;
• Missouri River Service Area I/I Reduction - Creve Coeur Creek East; and,
• Woods Mill Sanitary Relief (SKME-020).
The two remaining constructed SSOs, BP-036 and BP-037, will be eliminated as part of the work for
Creve Coeur Creek Sanitary Trunk Sewer Relief Phase VI (SKME-021). All remaining Master Plan
projects are scheduled for anticipated completion between 2020 and 2029. These projects will improve
sewer capacity, or correct defects and eliminate sources of I/I which 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 annually with
the SWMP Annual report. Completion of Master Plan projects will aid in the reduction of bacteria to
Creve Coeur 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.
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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.
CMOM activities will be carried out within the Creve Coeur 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 Creve Coeur 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.
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Within the Creve Coeur Creek watershed, there are 231 active FSEs and 12 that are listed as having been
decommissioned9. From 2016 to 2018, 360 FSE inspections were performed, resulting in 21 enforcement
actions. Over this same period, there were three sanitary sewer overflows caused by grease blockages.
Overtime, FOG activities are expected to reduce grease related sanitary sewer overflows and related
bacteria loading to Creve Coeur Creek.
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 Creve Coeur 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 Creve Coeur 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 5, and are set to begin the first year following removal of
the last constructed SSO in the Creve Coeur Creek watershed, which is tentatively 2021. Removal of the
last constructed SSO in the Creve Coeur Creek watershed will be accomplished by Creve Coeur Creek
Sanitary Trunk Sewer Relief Phase VI (SKME-021). This project will eliminate constructed SSOs BP-
036 and BP-037. Per the Consent Decree, Creve Coeur Creek Sanitary Trunk Sewer Relief Phase VI
(SKME-021) has a scheduled completion date of no later than August 10, 2020. Activities of this ARAP
as outlined in Table 5 shall commence in 2021. Thereafter, activities are scheduled by MS4 operating
permit year where applicable and are planned through 2029, aligning with the implementation schedule of
SSO Control Master Plan projects within Creve Coeur Creek. In the interim, similar ARAP activities will
have already been conducted in the Fishpot Creek Watershed. This will lend valuable experience and
other “lessons learned” which can be harnessed to ensure that effective approaches are implemented not
only in Creve Coeur Creek but other watersheds subject to future TMDL ARAPs.
Among the seven TMDL BMPs listed in Table 5, 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 currently scheduled
through 2029. Data obtained from visual inspections of the storm sewer system, including but not limited
to CCTV and Crawl Crew inspections, conducted under the Fishpot Creek bacterial TMDL ARAP will be
used to evaluate the effectiveness of visual storm sewer inspections overall and help determine the best
methods for this activity in Creve Coeur Creek and other watersheds with approved TMDLs for bacteria.
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 2029, 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 5 of this
section will be implemented according to the provided schedule only after this TMDL ARAP receives
9 FSE data regarding active and decommissioned establishments was obtained on 2/13/2019.
MSD & MS4 Co-permittees
Creve Coeur Creek bacteria TMDL ARAP
21
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 twice: 1) at the end of year five of the MS4 permit, and 2) in 2029 following
completion of SSO Control Master Plan projects in the Creve Coeur Creek watershed, in order to
determine if they should be replaced or modified.
MSD & MS4 Co-permittees
Creve Coeur Creek bacteria TMDL ARAP
22
Table 5. TMDL Best Management Practices Targeting Bacteria in the Creve Coeur Creek Watershed.
1BMP is based on outcome of SWMP BMP #36. The map will be used for channel inspections conducted in the fourth term MS4 permit. 2BMP is based on outcome of SWMP BMP #37. 3Last constructed SSOs (BP-036 and BP-037) are scheduled for removal on 8/10/2020 by Creve Coeur Creek Sanitary Trunk Sewer Relief Phase VI (SKME-021). ARAP Commences in year 2021. 4Denotes period for iterative review of BMP effectiveness.
# BMP Description BMP Purpose Expected
Result of BMP
Measurable Goals and Milestone Dates
Permit
Year 3,
2019
Permit
Year 4,
2020
Permit Year 5,
20213,4
2022
2023
2024
2025
2026
2027
2028
20294
BMP Evaluation
Process/Criteria
1
Determine extent of
rehabilitated sewers along
Creve Coeur Creek and
tributaries. Compare to in-
stream E.coli data.
Identify extent and
percent of rehabbed
sewers within defined
proximity to Creve Coeur
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 Creve Coeur
Creek and
tributaries.
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.
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 Creve Coeur
Creek.
Summary of
bacteria findings.
None None Commence visual
inspections.
Report findings
from 2021.
Continue visual
inspections.
Report findings
from 2022.
Continue visual
inspections.
Report findings
from 2023.
Continue visual
inspections.
Report findings
from 2024.
Continue visual
inspections.
Report findings
from 2025.
Continue visual
inspections.
Report findings
from 2026.
Continue visual
inspections.
Report findings
from 2027.
Continue visual
inspections.
Report findings
from 2028.
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
Creve Coeur Creek.
Summary of
response actions.
None None Respond to
bacteria findings
and eliminate
illicit discharges
identified during
visual inspections.
Report 2021
response actions.
Respond to
bacteria findings
and eliminate
illicit discharges
identified during
visual inspections.
Report 2022
response actions.
Respond to
bacteria findings
and eliminate
illicit discharges
identified during
visual inspections.
Report 2023
response actions.
Continue to
respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2024
response actions.
Continue to
respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2025
response actions.
Continue to
respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2026
response actions.
Continue to
respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2027
response actions.
Continue to
respond to bacteria
findings and
eliminate illicit
discharges
identified during
visual inspections.
Report 2028
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 Summarize 2020
E. coli loading and
trend.
Summarize 2021
E. coli loading and
trend.
Summarize 2022
E. coli loading and
trend.
Summarize 2023
E. coli loading and
trend.
Summarize 2024
E. coli loading and
trend.
Summarize 2025
E. coli loading and
trend.
Summarize 2026
E. coli loading and
trend.
Summarize 2027
E. coli loading and
trend.
Summarize 2028
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 Creve
Coeur 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 Develop map and
list of properties.
None None None None 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 Creve Coeur
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 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 Obtain 2020
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2021
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2022
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2023
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2024
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2025
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2026
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2027
records from
Hauled Waste
Program, add to
list, and report.
Obtain 2028
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
Creve Coeur Creek bacteria TMDL ARAP
23
4.0 Evaluation
Activities described in this TMDL ARAP will target bacteria sources in Creve Coeur 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. TMDL BMPs #2 and #3 are scheduled through 2029, but with information gathered under the
Fishpot Creek bacteria TMDL ARAP, 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 bacteria. 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 Creve Coeur Creek. TMDL BMP effectiveness will be largely
based on water quality data as evaluated under TMDL BMP #4. As appropriate, the status of each TMDL
BMP will accompany the annual SWMP report.
With the implementation of the Fishpot Creek Watershed ARAP commencing prior to this watershed,
opportunities for “lessons learned” exist. The outcomes of the pilot efforts accomplished in the Fishpot
Creek watershed may be considered for implementation into this ARAP, either as a modification to a
proposed activity or an additional activity. Such changes to this ARAP could occur either prior to, or
after its commencement, and would be subject to MDNR approval.
In line with MS4 Permit Section 3.1.2.1, implementation of the Creve Coeur Creek Bacteria TMDL
ARAP will be completed as soon as practicable, but is anticipated to span years or even multiple permit
terms.
MSD & MS4 Co-permittees
Creve Coeur Creek bacteria TMDL ARAP
Appendix A
SSO Control Master Plan Projects in the Creve Coeur Creek Watershed
MSD & MS4 Co-permittees Creve Coeur Creek bacteria TMDL ARAP
Project Name Plan/Phase Project Description Initial Design Commence - Complete
Construction*
Bellerive Sanitary Relief (Ladue Rd To Conway Rd) Master Plan Construct 2,400 ft. of 12-in. sanitary sewer 8/31/2020 2/17/2023 - 2/12/2024
Pub. San. Relief Pipe Construction 9/1/2020 2/1/2023 - 2/5/2024
CC-14 Creve Coeur Creek Sanitary Relief (SKME-026) Phase II Master Plan Construct 1,200 ft. of 18-in. sanitary sewer from
Hammermill Dr to Balcon Estates Road Prior to 12/31/2013 1/26/2015 - 1/21/2016
Pub. San. Relief Pipe Construction 9/9/2004 12/13/2013 - 7/9/2014
CC-17 Four Seasons Branch Sanitary Relief Master Plan Phase II of project to construct 3,300 ft. of 8-in. to 15-in. diameter
sewer and appurtenances and remove one SSO Prior to 12/31/2013 Prior to 12/31/2013 to 2/18/2016
Pub. San. Relief Pipe Construction 12/9/2010 10/11/2013 to 8/24/2015
Conway Meadows Sanitary Relief (Conway Rd To I-64) Master Plan Construct 1,500 ft. of 18-in. sanitary sewer 8/31/2023 2/16/2026 to 2/11/2027
Pub. San. Relief Pipe Construction 9/1/2023 1/31/2026 to 2/4/2027
Conway Village Sanitary Relief (Conway Rd to I-64) Master Plan Construct 3,600 ft. of 8-in. to 15-in. sanitary sewer 7/15/2017 1/1/2020 to 9/22/2021
Pub. San. Relief Pipe Construction 8/17/2017 10/23/2019 to 7/24/2021
Creve Coeur Creek (L-52) Force Main Improvements Phase II Master Plan Construct 3,500 ft. of 42-in. force main and appurtenances Prior to 12/31/2013 7/31/2014 to 1/22/2016
Force Main Force Main Construction Prior to 12/31/2013 5/13/2014 to 11/14/2014
Creve Coeur Creek I/I Reduction South East (I-64 and Mason Rd) Master Plan Construct 270 ft. of 8-in. sanitary sewer. Rehabilitate 4,800 ft. of 8-in. sewer.
Perform private I/I reduction at 130 properties 8/31/2016 8/16/2019 to 2/6/2021
Creve Coeur Creek Public I/I Reduction South Pub. I/I Red. Rehabilitate 84,000 ft. of the public sewer system using the
cured in place pipe method 8/5/2014 9/25/2019 to 10/4/2020
Creve Coeur Creek North East I/I Reduction (Olive Blvd and I-270) Master Plan Rehabilitate 50,000 ft. of 8-in. to 12-in. sewer 8/31/2016 8/16/2019 to 8/10/2020
Bissell - Coldwater - Missouri - Meramec Public I/I Reduction (2017)
Contract B Pub. I/I Red. Rehabilitate 56,000 ft. of the public sewer system using
the cured in place pipe method 7/29/2016 5/25/2019 to 11/25/2020
Creve Coeur Creek Sanitary Trunk Sewer Relief Phase VI (SKME-021) Master Plan Construct 7,750 ft. of 15-in. to 24-in. sanitary sewer, and eliminate
constructed SSO outfalls BP-036 and BP-037** 8/31/2016 2/17/2019 to 8/10/2020
Pub. San. Relief Pipe Construction 7/29/2016 5/25/2019 to 11/25/2020
Creve Coeur Creek Watershed Sanitary Sewer Rehabilitation Master Plan Rehabilitate 10 laterals, disconnect 2 roof drains, and disconnect
41 area drains. Eliminate constructed SSO outfall BP-039 Prior to 12/31/2013 Prior to 12/31/2013 to 2/21/2014
Creve Coeur Creek Public I/I Reduction Pub. I/I Red. Rehabilitation of approximately 48,000 ft. of sewer main,
750 manholes, and appurtenances 12/9/2010 6/7/2013 to 8/12/2016
Missouri River Service Area I/I Reduction - Creve Coeur Creek East Master Plan Rehabilitate public sewers using the cured-in-place pipe method 8/31/2014 8/15/2017 to 2/6/2019
Pub. I/I Red. Public Sewer Rehabilitation 8/5/2014 9/2/2015 to 12/18/2017
Nooning Tree Park Sanitary Relief (Whitree Ln to Brightfield Manor
Dr)
Master Plan Construct 3,600 ft. of 12-in. sanitary sewer 8/31/2023 2/16/2026 to 8/10/2027
Pub. San. Relief Pipe Construction 9/1/2023 1/28/2026 to 8/1/2027
Saylesville Sanitary Relief (Saylesville Dr to S Greentrails Dr) Master Plan Construct 3,920 ft. of 18-in. sanitary sewer 8/31/2021 2/17/2024 to 2/6/2026
Pub. San. Relief Pipe Construction 9/3/2019 3/2/2022 to 2/29/2024
MSD & MS4 Co-permittees Creve Coeur Creek bacteria TMDL ARAP
Project Name Plan/Phase Project Description Initial Design Commence - Complete
Construction
Smith Creek Ladue Road Sanitary Relief (Royal Manor
Dr to Hewlett Ct)
Master Plan Construct 5,200 ft. of 15-in. sanitary sewer 5/2/2022 10/18/2024 to 4/11/2026
Pub. San. Relief Pipe Construction 9/1/2021 9/29/2024 to 4/2/2026
White Plains Sanitary Relief (Cedar Creek Rd To E
Chesterfield Pky)
Master Plan Construct 5,000 ft. of 12-in. sanitary sewer 5/7/2025 10/24/2027 to 4/16/2029
Pub. San. Relief Pipe Construction 9/1/2024 9/26/2027 to 3/29/2029
White Plains Sanitary Relief (Saltbox Dr to Cedar Creek
Rd)
Master Plan Construct 2,500 ft. of 15-in. sanitary sewer 8/31/2020 2/17/2023 to 2/12/2024
Pub. San. Relief Pipe Construction 9/1/2020 2/3/2023 to 8/6/2024
Woods Mill Sanitary Relief (I-64 to Brook Mill Ln) Master Plan Construct 2,790 ft. of 8-in. to 15-in. sanitary sewer 8/31/2017 2/17/2020 to 2/11/2021
Pub. San. Relief Pipe Construction 8/11/2016 4/1/2020 to 4/6/2021
Woods Mill Sanitary Relief (SKME-020) Master Plan Construct 5,950 ft. of 8-in. to 24-in. diameter sanitary
relief sewers and appurtenances Prior to 12/31/2013 7/31/2014 to 4/21/2016
Pub. San. Relief Pipe Construction 12/10/2009 6/13/2014 to 5/8/2017
* Status updates will be provided for each Master Plan project listed in Appendix A and submitted annually with the SWMP Annual report.
** Constructed SSO outfalls BP-036 and BP-037 are the last two constructed SSO Outfalls remaining within the Creve Coeur Creek watershed.
MSD & MS4 Co-permittees Creve Coeur Creek bacteria 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 Strategy1,
completion of Escherichia coli (E. coli or bacteria) total maximum daily loads (TMDLs) for four
streams in the St. Louis area2, 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.
Bacteria and Nutrient BMP Strategy Review
December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
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.
Bacteria and Nutrient BMP Strategy Review
December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
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).
Bacteria and Nutrient BMP Strategy Review
December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
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 biofilters3 and subsurface flow wetlands4.
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.
Bacteria and Nutrient BMP Strategy Review
December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
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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December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
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
Document6.
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.
Bacteria and Nutrient BMP Strategy Review
December 23, 2016
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MOW5165E | St. Louis | 2016(1223)_MSD_BMP_Evaluation_Memo
quantity criteria7 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 BMP9 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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Document10 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 literature11 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 Systems12 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
MSD Structural BMP Evaluation
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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.