HomeMy Public PortalAboutExhibit MSD 37F - SSMIP 1995 Policy and Standards Reporti
i
i
i
i
i
i
i
i
i
i
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Policy and Standards Report
FINAL
III
Horner & Shifrin, Inc.
Engineers/Architects/Planners
Surveyors/Construction Managers
CDMCamp Dresser & McKee Inc.
October 1995
environmental'services
DRAFT
THE METROPOLITAN ST. LOUIS
SEWER DISTRICT
STORMWATER SYSTEM MASTER
IMPROVEMENT PLAN
POLICY AND STANDARDS REPORT
OCTOBER 1995
Prepared for:
METROPOLITAN ST. LOUIS SEWER DISTRICT
Prepared by:
Camp Dresser & McKee Inc.
233 South Wacker Drive
Suite 450
Chicago, Illinois 60606
and
Horner & Shifrin, Inc.
5200 Oakland Avenue
St. Louis, Missouri 63110
1:8108-001 LSTIO ULSICO V ER
TABLE OF CONTENTS
Section Page
Executive Summary ES 1-19
1.0 INTRODUCTION 1-1
1.1 Mission Statement, Goals and Objectives 1-1
1.2 Background and Purpose 1-5
1.3 Phase I Report Volumes 1-7
1.4 Phase I Stormwater Committees 1-7
1.5 Report Organization and Methodology 1-9
1.6 Study Area Physical Description 1-11
1.7 District Purpose and Organization 1-13
1.8 Legal Authority and Responsibilities 1-13
1.9 Needs, Problems and Issues 1-15
2.0 ASSESSMENT OF EXISTING STORMWATER MANAGEMENT PROGRAM
2.1 Introduction 2-1
2.2 Regulations and Standards 2-3
2.2.1 Level of Protection 2-4
2.2.2 Flow and Storage Methodology 2-9
2.2.3 Release Rate and Detention Basin Sizing 2-15
2.2.4 Floodplain Requirements 2-26
2.2.5 Development Site Erosion and Sediment (E&S) 2-29
Control
2.2.6 Water Quality 2-33
2.2.7 Channel Treatment 2-36
2.3 Engineering 2-41
2.3.1 Plan Review and Inspection 2-41
2.3.2 Mapping and Database Information 2-51
2.4 Operation and Maintenance 2-56
2.4.1 Maintenance Responsibilities and Frequency 2-56
2.4.2 Detention Basin Maintenance 2-67
2.4.3 Access and Preservation of Drainage Paths 2-75
2.5 Capital Improvements 2-80
2.5.1 Prioritization of Capital Projects 2-82
2.5.2 Buyouts 2-88
2.6 Funding 2-92
3.0 IMPLEMENTATION OF STORMWATER MANAGEMENT PROGRAM
3.1 Legal Authority, Rules and Regulations 3-1
3.2 Planning Tools 3-2
3.3 Funding 3-3
1:816&U01-ST.LOUIS\TOC i
3.4 Adoption of the Stormwater Management Program 3-3
3.5 Summary of Implementation Recommendations 3-5
4.0 REFERENCES
I:8108-001-ST.LOUIS TCC
LIST OF TABLES
Tables raga
1-1 MSD Responsibility Areas and Powers for Stormwater
Management
1-16
1-2 PAC and TAC Priority Stormwater Issues (2 pages) 1-18
2-1 Stormwater Quantity Design Criteria for Several Urban Areas 2-6
2-2 Preliminary Estimates of Detention Storage Volumes for Various 2-22
Release Rate Approaches
2-3 Qualitative Comparison of Detention Approaches 2-24
2-4 Maintenance Activities from July 1992 to June 1993 2-59
2-5 Suggested Maintenance Activities and Frequencies 2-66
2-6 Maintenance Activities for Detention Basins 2-70
2-7 Cost Estimate for Detention Basin Maintenance 2-72
2-8 FY 1994 Stormwater Expenditures 2-94
2-9 MSD Existing Stormwater Rates 2-96
2-10 FY 1994 Stormwater Revenue 2-98
2-11 MSD Projected Stormwater Expenditures FY 1998-2003 2-100
2-12 Stormwater Funding Examples 2-102
2-13 Funding Mechanism Comparison Matrix 2-108
2-14 Example 0 & M Program Costs for MSD Customers 2-116
2-15 Example Capital Improvement Program Costs for MSD Customers 2-117
L•8308.OQ 1-ST.LOUIS\TOC
iii
LIST OF FIGURES
Figures rage
1-1 Municipalities in the MSD Service Area 1-6
1-2 Watersheds in the MSD Service Area 1-12
1-3 MSD Department and Offices Involved in the Stormwater 1-14
System Master Improvement Plan (SSMIP)
2-1 Alternate Methods for Release Rate and 2-18
Detention Basin Sizing
2-2 Plan Review and Inspection Flowchart (2 pages) 2-43
2-3 Stormwater Maintenance Responsibility Matrix 2-63
1:8108-001-$T,LOULS\TOC
iv
EXECUTIVE SUMMARY
POLICY AND STANDARDS REPORT
INTRODUCTION
Stormwater Management Program Goals
The Stormwater System Master Improvement Plan (SSMIP) will develop
solutions to resolve stormwater problems throughout the Metropolitan St.
Louis Sewer District (MSD). In support of this mission, six goals were
developed relating to:
• Establishing Appropriate Stormwater Policies and Criteria
• Expanding Public Involvement and Information Activities
• Completing a System Inventory and Developing Efficient Data
Management Procedures
• Preparing Watershed Management Plans
• Identifying Needed Capital Improvements
• Securing Adequate Funding for Stormwater Services
The Policy and Standards Report addresses and makes recommendations
regarding two key goals critical to the success of the SSMIP. The Policy and
Standards Report:
• Develops stormwater policies and design criteria which will provide a
uniform cost-effective, and equitable level of protection for all citizens.
• Recommends an appropriate funding mechanism to allow MSD to carry
out the stormwater management program and provide reliable and
responsive stormwater service.
Policy & Standards Report ES-1
1:6108-0015st I o u isSg&pex ec
Executive Summary
Policy and Standards Report
The Policy and Standards Report documents the process and recommendations
for evaluating and developing storrnwater policies, design criteria and funding.
It includes a list of needs, issues, and
stormwater problems that were
identified and reviewed by MSD staff
and its stormwater consultants. Each
need or issue was evaluated in terms of
its relationship to MSD's authority to
provide stormwater management
services within the District's boundaries.
Specific recommendations are presented
to address each major issue to meet the
expectations of the public (MSD's
customers) and to provide a level of
service consistent with MSD's responsibility to protect citizens' health, safety,
welfare and quality of life.
The Policy and Standards Report
documents the process and
recommendations for evaluating and
developing stormwater policies,
design criteria and funding.
MSD Authority and Responsibility
MSD received its authority for management of the storm system through its
"Plan" passed by special election in 1954.
Originally only responsible for the area
The Plan grants MSD jurisdiction
control, possession and
supervision of all facilities for the
collection and disposal of
sanitary sewerage and
stormwater.
comprising the City of St. Louis and the
area generally within the Interstate 270
outer belt, in 1977 MSD's boundaries were
extended to include most of the
remainder of St. Louis County, the
"Annexed Area." MSD currently operates
combined and separate sewer systems
within its 524 square mile service area.
The Plan grants MSD jurisdiction, control,
possession and supervision of all facilities
for the collection and disposal of sanitary
sewerage and stormwater. Responsibilities include:
• Preparation of Design Standards
• Engineering functions relating to planning, design and construction
■ Review and permitting of new development plans
• Capital Improvements
Policy & Standards Report
ES-2
1:8108-001'st.Iouis\g8 pexec
Executive Summary
• Operations and Maintenance of the stormwater drainage system
This authority is sufficient to provide stormwater management services across
the District. However, these stormwater services are not being provided at an
acceptable level both from the District's and the public's perspective because of
inadequate funding and limited resources, unclear or unexercised authority
and sometimes ineffective design criteria and standards.
POLICY AND STANDARDS RECOMMENDATIONS
The first phase of the SSM IP included this Policy and Standards Report
component to review known problems and needs and establish stormwater
policies and standards to provide a desired and acceptable level of service to
the public. The process of identifying needs and issues and recommending
solutions involved a number of workshop -meetings with three committees to
educate, involve, solicit feedback and build consensus with representatives
from the technical community, local municipalities, developers, elected
officials, industry, environmental and other special interest groups. This
process is presented in greater detail at the end of the Executive Summary.
The committees identified 34 priority stormwater issues and produced a
number of recommendations to address each. The following pages highlight
the major recommendations for Board consideration. Each recommendation
includes a summary of the problem, current District policy or procedures,
recommended changes, and the benefits for the public.
Policy & Standards Report ES-3
1:8108-001Ast.lou Is\g&pexec
Executive Summary
Recommendation
No, 1
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO, 1
Implement a funding source based on impervious area with tiered
rates for the numerous smaller properties such as those in the residential
category.
Current funding is not adequate to support a comprehensive stormwater
program, is not based on causative factors such as the contribution of runoff,
and varies widely across the District and between customers.
Stormwater services are funded through a grossly inadequate flat charge (24(p
per month) and one or more ad valorem taxes that support additional
stormwater services in the areas they are levied.
Impervious area charges with tiered rates for groups or classes of
smaller parcels and actual area charges for larger parcels. This approach
represents a compromise between basing charges on causative factors and ease
of understanding by the public, which will aid in voter acceptance.
Provides a stable and dedicated funding source that is based on causative
factors whereby all customers pay and is adequate to support comprehensive
stormwater management services.
Policy & Standards Report
1:8108-COTLst.louiskl&pexec
ES-4
Executive Summary
Recommendation
Na 2:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 2
Improve the frequency and responsiveness of stormwater maintenance and
extend services to the Annexed Area.
The lack of funding for stormwater system maintenance has limited the re-
sources and manpower available to keep the drainage system functioning
properly. Only reactive maintenance activities are provided in the Original
Area and only emergency services are provided in the Annexed Area.
In the Original Area, where stormwater taxes are collected, maintenance is
reactive, being conducted on storm sewers and channels in response to com-
plaints and identified problems. In the Annexed Area, only emergency situa-
tions receive maintenance services where safety or property are significantly
threatened.
Commensurate with increased funding, upgrade the stormwater
maintenance services to a preventative level and improve the complaint
response time throughout the District
Preventative stormwater maintenance and timely complaint response will
reduce the number of flooding and erosion problems as well as the potential
for stormwater damages. Improved responsiveness will raise the public's
perception of MSD and the services it provides.
Policy & Standards Report
1:81 cB-601\st.louislg&pexec
ES-5
Executive Summary
Recommendation
No. 3:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO, 3
Provide detention basin maintenance services in residential areas.
Detention basin maintenance is inadequate because property owners are not
aware of or are unable or unwilling to fulfill this responsibility. This situation
jeopardizes the structural integrity of the basins, causes detention basins to
function improperly or ineffectively, and can lead to increased flooding and/or
erosion problems.
MSD executes a maintenance agreement for detention basins with the property
owner or homeowner association responsible for maintenance in residential
areas.
Provide and/or contract for maintenance services of residential detention
basins subject to available funding.
Ensuring proper detention basin maintenance will promote proper functioning
of the drainage system and thus, reduce or alleviate stormwater flooding and
erosion problems. Proper maintenance also improves the aesthetics of
detention basins.
Policy & Standards Report
1:81 o9.001,sl.Iout&g&pexec
ES-6
Executive Summary
Recommendation
No. 4
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 4
Require an "overflow/ design" concept that provides a 100-year level of
protection for all future drainage improvements.
Localized flooding and damages occur when rainfall exceeds system capacity
or when the system is obstructed or plugged.
Only the "design" system is required, that is, the pipe or channel
improvements, to pass the 15-year design event (20-year in the City of St.
Louis).
Require an "overflow" system that functions when the capacity of
the "design" system is exceeded or when the design system cannot function as
designed. Develop the overflow system to provide a 100-year level of
protection which is the "Standard in the Industry." The overflow system
typically provides an overland flow path for the water to follow without
causing property damage.
EIiminates localized flooding and damage of adjacent structures by providing
designated areas for flows and ponding during major rainfall events and
increases the overall level of protection from flooding.
Policy & Standards Report
I:8108-001\st.Iouislg .pezee
ES-7
Executive Summary
Recommendation
No. 5
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 5
Revise detention basin design criteria to incorporate a 100-year level of
protection and appropriate release rate criteria that mitigates downstream
impacts from development.
Current detention basin design criteria is not effective in controlling flow and
volume increases from development. The result is increased downstream
erosion and flooding problems.
MSD design criteria requires that up to the 15-year storm be detained with
post -development release rates not to exceed the pre -development release rates
at the outlet from the development.
Upgrading the level of protection to the 100-year event along with a
further restricted release rate are required to ensure that flooding and erosion
damages are not increased downstream.
Protects downstream properties from adverse effects of development up to the
100-year event.
Policy & Standards Report
1:8108-001151. I p u islg 8 p e x ec
ES-8
Executive Summary
Recommendation
No. 6:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 6
Update the existing MSD ordinance and develop a model stormwater
ordinance for local communities that will present new MSD standards and
criteria and will supplement these standards in important areas where MSD
authority is limited.
1. Recommended standards and design criteria changes in the Policy and
Standards Report will require MSD to update its existing stormwater ordi-
nance. This will require similar updates by all municipalities in
the District.
2. Certain stormwater problems result from activities that are outside of MSD
authority or responsibility that are not adequately regulated at the local
municipal level, or are regulated with inconsistent standards, such as ero-
sion and sediment control.
Local ordinances reflect the existing minimum standards of MSD, which will
need to be revised.
Update the existing stormwater ordinance to reflect the recommended changes
in policy and standards. Develop a model ordinance that will provide consis-
tent minimum standards of MSD and include other requirements for erosion
sediment control and floodplains which are outside MSD's authority and
responsibility.
Provides clear, consistent and comprehensive regulations at the local level to
implement an effective stormwater management program.
Policy & Standards Report ES-9
I:81 O8-OO t is t. io u l slg & pe xa c
Executive Summary
Recommendation
No, 7:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 7
'Buyout" properties that axe subject to stormwater damage when socio-politi-
cally acceptable and more cost-effective than other alternatives.
Structural solutions to flooding and erosion problems sometimes exceed the
value of the affected property and thus do not offer a cost-effective solution.
Property buyouts are not actively pursued by MSD.
Seek available state funding and evaluate buyouts on a case by case
basis during preparation of watershed plans giving consideration to local
government and community acceptability and the full economic impact of the
buyout.
More cost-efficient solutions to stormwater problems allowing the available
funds to be used to solve the maximum number of problems.
Policy & Standards Report
1:8108.001Lzt.loulskg&pexec
ES-10
Executive Summary
Recommendation
Na 8:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 8
Improve the prioritization procedure for stormwater projects to be more cost-
efficient and consider a full range of projects and potential benefits.
Current policy does not adequately consider project benefits, costs or the
number of people benefitted.
The current MSD prioritization ranks all projects on a scale of 1-9 based on
immediate threat to public safety, property, or vehicular access.
Institute a prioritization procedure that applies to all potential
projects and includes a comprehensive range of benefit criteria that maximizes
objectivity and a benefit to cost comparison that promotes cost -efficiency.
Allows for an objective, cost-effective ranking of stormwater projects to maxi-
mize the benefits and spend the available funds where they can accomplish the
most.
Policy & Standards Report
I:8108-OO1\ .loutstig&pexec
ES-11
Executive Summary
Recommendation
No. 9:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 9
Revise the design criteria for utilization of sinkhole areas to provide
conveyance and / or storage for up to the 100-year event.
Current sinkhole design criteria do not require planning for the 100-year event
which results in flooding of these areas.
MSD requires that sinkhole areas be provided with relief via a storm sewer for
up to the 15-year event assuming zero natural discharge from the sinkhole.
Upgrade sinkhole development requirements to provide an overland flow path
or designated ponding area for up to the 100-year event in order
to have a properly functioning "overflow" drainage system.
Reduced flooding impacts in sinkhole areas as a result of development.
Policy & Standards Report
I:8 t 08-001 Lst.to u istigspexec
ES-12
Executive Summary
Recommendation
No. 10:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 10
Expand the list of allowable methods used for stream bank stabilization and
accept maintenance responsibility for all approved channels.
The currently allowable channel linings are expensive and are not always
adequate to fulfill the full range of project objectives in a reliable and cost-
effective manner.
MSD channel improvement projects typically use concrete walls or grouted or
dumped rip rap to repair channel erosion problems and these are the only
types of improvements accepted for maintenance.
Alternate channel improvements may be preferable for certain projects
depending on site conditions, downstream effects and other project objectives
(aesthetics, etc.) and should not be precluded from consideration. MSD would
maintain approved channels.
Potential cost savings and better ability to meet multiple project objectives with
other channel improvement options. MSD maintenance of all approved chan-
nel projects.
Policy & Standards Report
18108-001lst.lou i s\g8 pe xee
ES-13
Executive Summary
Recommendation
No. 11:
Problem:
Current Policy:
Recommended
Policy:
Benefits:
RECOMMENDATION NO. 11
Raise public awareness of the stormwater impacts on water quality and
revise/ prepare standards that allow voluntary inclusion of stormwater quality
benefits and retrofit ability.
Federal regulations on stormwater quality are likely to affect the St. Louis area
in the future. Although the actual requirements are still evolving, MSD could
be required to regulate and manage the water quality aspects of stormwater.
MSD's current stormwater program does not give consideration to water
quality except as it relates to combined sewers and separate sewer overflows.
In order to prepare for future requirements, MSD should promote stormwater
quality awareness and incorporate other water quality measures or guidance as
appropriate into its projects and regulations.
Proactive approach to water quality issues that encourages environmental
benefits without mandatory requirements.
Policy & Standards Report
1:8 t 06-00 ristiouislg&pexec
ES-14
Executive Summary
SUMMARY
In general, implementation of these recommendations provide the District
with:
1. Improved drainage design and level of protection (100-year) in new
developments.
2. A model stormwater ordinance for adoption by municipalities in the
District to improve stormwater system design, inspection, operation,
maintenance and performance.
3. Expanded, more frequent and proactive maintenance activities through-
out the District, but especially in the Annexed Area and, if funding is
provided, maintenance for residential detention basins.
4. A new source of revenue (impervious charge) that provides sufficient
funds to meet the required level of service (both maintenance and
replacement projects) and ensures that ali customers who benefit from
MSD's stormwater services pay according to the services they receive.
Implementation of these recommendations will enable the District to
provide stormwater services which substantially limit existing flooding
and erosion problems, minimize future problems, and help meet the
expectations of the public in terms of operation, maintenance and per-
formance of the stormwater drainage system.
REQUIRED ACTION
MSD staff requests Board consideration in adopting the Policy and Standards
Report and to direct staff to prepare an implementation plan to address the
following:
1. Revise the existing MSD stormwater ordinance to reflect recommended
policy and standards changes.
2. Update and revise the stormwater aspects of the "Rules and Regula-
tions" to provide technical support for the new stormwater policy and
standards.
3. Develop and adopt a funding ordinance that will provide adequate
funding based on impervious area charges to all customers who con-
tribute runoff to MSD's stormwater system.
4. Initiate steps to proceed with implementation of the stormwater charge.
Policy & Standards Report
1:810B-00l s[.loulslg&pexec
ES-15
Executive Summary
5. Conduct appropriate public information and involvement activities to
inform and educate the public regarding the recommended changes in
MSD stormwater policy and standards.
POLICY AND STANDARDS DEVELOPMENT
PROCESS
The process of identifying stormwater needs and issues and establishing
appropriate stormwater policy and standards involves several committees
comprising MSD staff, representatives from the technical committee, the
public, and special interest groups. These committees met a number of
times over a nine month period to develop the recommendations.
Stormwater Steering Committee
The first committee, the Stormwater Steering Committee (SSC) comprised
key MSD staff and three stormwater consulting teams. Staff representation
included Engineering on a regular basis with as -needed participation from
General Counsel, Maintenance, Environmental Compliance, Communica-
tions, Mapping, Finance, Wastewater, and the Director's office. The SSC
served as an internal working committee which developed the initial poli-
cies and standards.
Technical Advisory Committee
The Technical Advisory Committee (TAC) comprised key MSD staff and its
lead stormwater consultant, Horner and Shifrin/CDM, and technical repre-
sentatives from Chesterfield, Florissant, St. Louis County, the City of St.
Louis, the Home Builders Association, the Associated General Contractors,
University of Missouri -Rolla, Missouri Department of Conservation and the
U.S. Army Corps of Engineers. The TAC served as a technical sounding
board for all policy issues, but primarily focused on technical issues relat-
ing to standards and criteria such as technical procedures and detention
basin sizing methodology and criteria.
Public Advisory Committee
The Public Advisory Committee (PAC) comprised key MSD staff and
Horner and Shifrin/CDM and representatives from the "non -technical"
public group and "special interest" groups such as, the City of Glendale
(Mayor), Home Builders Association, Missouri Growth Association,
Monsanto Corporation, Boatmen's Community Development Corporation,
League of Women Voters, St. Louis County (Council), St. Louis (Alder-
man), Community Association Institute, Coalition for the Environment and
Policy & Standards Report
1:81 aB-0011st.IouIslg&pexec
ES-16
Executive Summary
the U.S. Army Corps of Engineers. The PAC reviewed and assisted in
devel
oping primarily non -technical policies focusing on general stormwater,
maintenance and responsibility, and funding needs/issues.
The needs and issues, as well as the recommendations contained in this
report were discussed and evaluated with the SSC, TAC and PAC. Al-
though differing views and perspectives were expressed, general concur-
rence was obtained on each issue.
Stormwater Needs and Issues
In the process of working with the SSC, TAC and PAC to define current
MSD authority, responsibilities and
problems, a number of major
A total of 34 needs and issues
were identified from District staffs
first-hand knowledge and com-
plaint files as well as surveys of
TAC and PAC members.
stormwater needs and issues were iden-
tified. A total of 34 needs and issues
were identified from District staffs first-
hand knowledge and complaint files as
well as surveys of TAC and PAC mem-
bers. This approach provided MSD
with feedback based on a broad per-
spective from technical and non -techni-
cal, staff and public audiences. The
needs and issues are summarized in the
Policy and Standards Report and are
grouped in five areas: Institutional; Technical; Maintenance; Funding; and
Public Involvement & Information (PI&I).
Institutional
The Institutional area included needs/issues that dealt with jurisdiction or
control; authority; organizational limitations and stormwater policy. These
needs and issues primarily related to who
These needs and issues primarily
related to who has the authority and
responsibility to provide storm water
services and why these services are
inadequate or simply not provided.
has the authority and responsibility to
provide stormwater services and why
these services are inadequate or simply
not provided. A fundamental need that
was identified was to clearly define au-
thority, responsibilities and requirements
relative to stormwater management
among MSD, the County and the munici-
palities. The policy side of these needs
and issues dealt with the level of service
provided by MSD and the expectations of the public; that is, MSD should
Policy & Standards Report ES-17
t:61 as-aa tlss.iouLs\g&pexec
Executive Summary
provide a higher level of service so that stormwater flooding occurs less
frequently.
Technical
Technical needs/issues focused mainly on standards and procedures that
must be in place to carry out MSD's stormwater policies; for example, How
is the size of a detention basin determined? Or, how are capital projects
prioritized for construction.
Maintenance
Maintenance needs/issues related primarily to problems caused by actual
or perceived inadequate maintenance or unfilled expectations relative to
the level of service provided by MSD. This was especially true in the
Annexed Area where maintenance is limited to reactive or emergency
activities because of funding limitations. Inadequate detention basin main-
tenance was identified as a major concern.
Funding
The lack of funding is the root cause of many of the stormwater problems
experienced across the District, However,
rate changes and alternative funding mecha-
The lack of funding is the root
cause of many of the stormwater
problems experienced across the
District.
nisms are limited by existing legal and polit-
ical constraints that require voter approval
to achieve any significant increases in fund-
ing. To address the Ievel of funding, the
District must answer the questions of: How
much revenue is needed? What mechanism
should be used to collect the funding? Who
should pay for the required stormwater ser-
vices? And, how will this funding source be implemented?
Policy & Standards Report
1:8108 - 0011sM o u i s\g & pe x ec
ES-18
Executive Summary
Public Involvement and Information
Public Involvement and Information (PI&I) was also identified as an area
falling short of the require-
ments to adequately inform the
public of the problems and so-
lutions associated with
stormwater, thus further exac-
erbating the actual and per-
ceived service and operational
problems now faced by MSD.
Although not addressed in this
report, MSD has undertaken a
proactive PI&I program to fa-
cilitate better communication,
education, involvement, feed-
back and consensus -building to
result in a more informed public and to raise the overall image of the Dis-
trict with regard to stormwater services. The interaction with the TAC and
PAC was the first step in implementing this PI&I program.
MSD has undertaken a proactive Pl&I program
to facilitate better communication, education, in-
volvement, feedback and consensus -building to
result in a more informed public and to raise the
overall image of the District with regard to
stormwater services.
Policy & Standards Report
t:8108-001 \st.louis\g&pexee
ES-f 9
1.0 INTRODUCTION
1.1 MISSION STATEMENT. GOALS AND OBJECTIVES
The mission of the Stormwater System Master Improvement Plan (SSM P) is to provide a
comprehensive and coordinated plan, that when implemented will resolve stormwater
problems throughout the Metropolitan St. Louis Sewer District (MSD). To achieve this
mission, the following goals must be met:
$SMIP Goals
• Stormwater Policies and Design Criteria
Develop stormwater policies and design criteria which will provide a uniform,
cost-effective, and equitable level of protection for all citizens.
• Public Involvement and Information
Establish a public relations program to inform and obtain input from the
community and its citizens to build the necessary public support for a
successful stormwater management program:
System Inventory and Data Management
Collect and compile stormwater system data and develop a data management
system compatible with MSD's Automated Systems to make data readily
available for maintenance and planning.
• Watershed Management Plan
I:8108-001 \stlou\sectionl
Develop analysis criteria and procedures which MSD personnel can use to
1-1
effectively manage maintenance, development, and capital improvement
projects.
• Capital Improvement Program
Develop a program which identifies, prioritizes, and estimates costs of projects
that mitigate stormwater problems.
• Funding
Identify and implement an appropriate funding source and mechanism to
allow MSD to carry out the stormwater management program and thereby
provide reliable and responsive stormwater service.
With the mission statement and goals in place, the SSMIP committees (see Section 1.4)
formulated objectives to address the major stormwater needs and issues. The objectives were
discussed and modified until a reasonable consensus was reached. These objectives were
then used to guide the recommendations for MSD policy and standards on each of the major
stormwater issues. These objectives are listed below and can also be found throughout
Section 2 as they relate to the assessment of specific policy issues.
SSMIP Objectives,
• Select a level of protection from potential stormwater damages that is cost-
effective, generally consistent with standards from other urban areas, and
acceptable to property owners in the District.
• Provide a standard methodology that appropriately balances accuracy and
simplicity for calculating flows and storage parameters used in the design of
drainage facilities in the District.
I:8108-001 \s tiou \ sectionl
1-2
" L i m i t l o c a l , p o s t - d e v e l o p m e n t p e a k f l o w s s o t h a t d o w n s t r e a m p e a k f l o w s a r e
n o t i n c r e a s e d a b o v e p r e - d e v e l o p m e n t c o n d i t i o n s .
" W o r k i n g w i t h i n M S D ' s a u t h o r i t y , m i n i m i z e t h e d e t r i m e n t a l e r o s i o n e f f e c t s
a s s o c i a t e d d e v e l o p m e n t e s p e c i a l l y w i t h r e s p e c t t o c a p a c i t y a n d m a i n t e n a n c e o f
d r a i n a g e f a c i l i t i e s .
" D e f i n e t h e r o l e o f w a t e r q u a l i t y i n t h e M S D ' s S S M I P .
" D e f i n e a c c e p t a b l e c h a n n e l b a n k ( s i d e w a l l ) a n d b o t t o m m a t e r i a l s a n d
p r o c e d u r e s t h a t p r o m o t e p r o p e r d r a i n a g e s y s t e m f u n c t i o n a n d d e f i n e u n d e r
w h a t c o n d i t i o n s M S D w i l l m a i n t a i n c h a n n e l i m p r o v e m e n t s .
" R e v i e w p l a n s a n d i n s p e c t d r a i n a g e f a c i l i t y c o n s t r u c t i o n a t a s u f f i c i e n t l e v e l t o
e n s u r e c o m p l i a n c e w i t h M S D s t a n d a r d s a n d c r i t e r i a .
" P r o v i d e t i m e l y , c o m p r e h e n s i v e a n d a c c u r a t e d a t a o n t h e d r a i n a g e f a c i l i t i e s i n
t h e M S D s e r v i c e a r e a t o e f f e c t i v e l y p l a n a n d m a i n t a i n t h e o v e r a l l s t o r m w a t e r
s y s t e m .
" D e f i n e m a i n t e n a n c e r e s p o n s i b i l i t i e s a n d f r e q u e n c y o f m a i n t e n a n c e g o a l s t h a t
e n s u r e p r o p e r f u n c t i o n a l i t y o f t h e d r a i n a g e s y s t e m a c r o s s t h e e n t i r e s e r v i c e
a r e a .
" P r o v i d e t h e n e c e s s a r y a c c e s s a n d a r e a t o c o n d u c t m a i n t e n a n c e , i n s p e c t i o n ,
r e p l a c e m e n t , a n d o t h e r s e r v i c e s r e l a t e d t o M S D ' s s t o r m w a t e r p r o g r a m a s w e l l
a s t o p r e s e r v e d e s i g n a t e d d r a i n a g e w a y s .
" D e v e l o p a s y s t e m f o r r a n k i n g c a p i t a l i m p r o v e m e n t p r o j e c t s t h a t i s o b j e c t i v e ,
c o s t - e f f i c i e n t , r e a d i l y u n d e r s t a n d a b l e a n d c o n s i d e r s a r a n g e o f p o t e n t i a l
b e n e f i t s .
I : 8 1 0 8 - 0 0 1 \ s t l a u l s e c t i o n l
1 - 3
" C o n s i d e r p r o p e r t y a c q u i s i t i o n a n d b u i l d i n g r e m o v a l f r o m t h o s e p r o p e r t i e s
( b u y o u t s ) w h i c h a r e s u b j e c t t o r e p e a t e d f l o o d i n g o r e r o s i o n d a m a g e w h e n
m o r e c o s t - e f f e c t i v e t h a n o t h e r a l t e r n a t i v e s a n d w h e n s o c i o - p o l i t i c a l l y
a c c e p t a b l e .
" P r o v i d e a s t a b l e , d e d i c a t e d , e q u i t a b l e , a d e q u a t e , a n d i m p l e m e n t a b l e s o u r c e o f
f u n d i n g t o s u p p o r t a c o m p r e h e n s i v e s t o r m w a t e r m a n a g e m e n t p r o g r a m .
A t h r e e - p h a s e d a p p r o a c h h a s b e e n a d o p t e d f o r t h e d e v e l o p m e n t o f t h e S S M I P t o w o r k w i t h i n
t h e c u r r e n t f u n d i n g o f M S D :
" P h a s e I
G o a l s a n d o b j e c t i v e s w i l l b e e s t a b l i s h e d t h a t f o r m t h e f o u n d a t i o n a n d o v e r a l l
g u i d a n c e f o r t h e s t o r m w a t e r m a n a g e m e n t p r o g r a m , i n c l u d i n g a r e v i e w o f
e x i s t i n g r e s p o n s i b i l i t i e s , s t a n d a r d s a n d c r i t e r i a . A l s o d u r i n g t h i s p h a s e , a l l
p e r t i n e n t d a t a f o r d e a l i n g w i t h s t o r m w a t e r m a n a g e m e n t w i l l b e r e v i e w e d a n d
s u m m a r i z e d , a n d t h e m e t h o d o l o g y t o b e u s e d i n t h e i n d i v i d u a l w a t e r s h e d
m a s t e r p l a n s w i l l b e d e t e r m i n e d a n d d o c u m e n t e d .
" P h a s e I I
L 8 1 0 8 0 0 1 \ s t t o u \ s e c t i o n l
S t o r m w a t e r m a s t e r p l a n s w i l l b e c o m p l e t e d f o r e a c h o f t h r e e p i l o t w a t e r s h e d s .
P o l i c i e s a n d s t a n d a r d s d e t e r m i n e d i n P h a s e I w i l l b e t e s t e d a n d v e r i f i e d
t h r o u g h t h e u s e o f c o m p u t e r m o d e l s f o r t h e p i l o t w a t e r s h e d s . T h e s e m o d e l s
w i l l a l s o b e u s e d t o d e v e l o p s o l u t i o n s w h i c h w i l l e f f e c t i v e l y d e a l w i t h e r o s i o n
a n d f l o o d i n g i s s u e s .
1 - 4
" P h a s e I I I
S t o r m w a t e r m a s t e r p l a n s w i l l b e c o m p l e t e d f o r e a c h o f t h e r e m a i n i n g 2 2
w a t e r s h e d s t o p r o v i d e a p r i o r i t i z e d l i s t o f i m p r o v e m e n t s t o b e i m p l e m e n t e d b y
M S D a s f u n d i n g i s a v a i l a b l e .
1 . 2 B A C K G R Q U N D A N D P U R P O S E
M S D r e c e i v e d a u t h o r i t y f o r m a n a g e m e n t o f s a n i t a r y a n d s t o r m s y s t e m s w h e n t h e v o t e r s
a p p r o v e d t h e D i s t r i c t ' s P l a n i n 1 9 5 4 . O r i g i n a l l y t h e M S D s e r v i c e a r e a i n c l u d e d t h e C i t y o f S t .
L o u i s a n d s u r r o u n d i n g m u n i c i p a l i t i e s g e n e r a l l y w i t h i n t h e I n t e r s t a t e 2 7 0 o u t e r b e l t . I n 1 9 7 7 ,
t h e M S D b o u n d a r i e s w e r e e x t e n d e d t o i n c l u d e m o s t o f t h e r e m a i n d e r o f S t . L o u i s C o u n t y .
T h e c u r r e n t M S D s e r v i c e a r e a e n c o m p a s s e s a t o t a l o f 5 2 4 s q u a r e m i l e s , o v e r 9 0 m u n i c i p a l i t i e s ,
a s w e l l a s u n i n c o r p o r a t e d a r e a s o f S t . L o u i s C o u n t y . F i g u r e 1 - 1 p r e s e n t s a m a p o f M S D ' s
s e r v i c e a r e a a n d t h e m u n i c i p a l i t i e s i n t h e S t . L o u i s M e t r o p o l i t a n A r e a .
M S D f a c e s a n u m b e r o f d i f f i c u l t s t o r m w a t e r m a n a g e m e n t c h a l l e n g e s i n b o t h t h e o r i g i n a l a n d
a n n e x e d a r e a s . S t o r m w a t e r p r o b l e m s i n c l u d e o v e r b a n k f l o o d i n g o f t h e l o c a l s t r e a m s ,
f l o o d i n g a l o n g t h e f l o o d p l a i n s o f t h e m a j o r r i v e r s ( M i s s o u r i , M e r a m e c , a n d M i s s i s s i p p i ) ,
s t r e e t f l o o d i n g , s t r e a m s b l o c k e d b y d e b r i s , a n d e r o s i o n o f s t r e a m b a n k s d u e i n p a r t t o
i n c r e a s e d f l o w s a n d v e l o c i t i e s o f s t o r m w a t e r t h a t h a s r e s u l t e d f r o m u r b a n i z a t i o n . E x p a n d e d
s t o r m w a t e r a n d d r a i n a g e r e l a t e d p r o b l e m s h a v e h e i g h t e n e d p u b l i c d e m a n d f o r M S D t o a c t
o n s t o r m w a t e r i s s u e s . A l s o , t h e p o t e n t i a l i m p l e m e n t a t i o n o f a n e w s t o r m w a t e r f u n d i n g
m e c h a n i s m ( t h e i m p e r v i o u s c h a r g e ) , c o m b i n e d w i t h a n i n c o m p l e t e k n o w l e d g e o f t h e
s t o r m w a t e r s y s t e m a n d t h e a b s e n c e o f a l o n g t e r m p l a n f o r i m p r o v e m e n t s d e m o n s t r a t e s t h e
n e e d f o r a c o m p r e h e n s i v e S t o r m w a t e r S y s t e m M a s t e r I m p r o v e m e n t P l a n ( S S M I P ) .
M S D r e t a i n e d t h e f o l l o w i n g c o n s u l t a n t e n g i n e e r i n g t e a m s t o a s s i s t w i t h d e v e l o p m e n t o f t h e
S S M I P :
" H o m e r a n d S h i f r i n , I n c . ( H & S ) w i t h C a m p D r e s s e r & M c K e e I n c . ( C D M ) w h i c h
f u n c t i o n s a s t h e l e a d c o n s u l t a n t t e a m ( L C T e a m ) ,
I : 8 1 0 8 - 0 0 1 \ s i o u \ s e c p o n I
1 - 5
2 °Oa 3" .1xR illf 01 PI30°0E
] B6EfranTMR M1VC140P5 1] RgdsSMr 54 PAyppu 3.y5
s11n+!ERNE lal ee RE�@1•[L OEN
45 PPEEA AE* a.aoc
0 ea-NOfi ]E4�lEa1 EW0 PHM 30 P.C. LAWN
E 11E3E171;17LLs ]0 �EF004E PUKE
Pi 3.10R5'EN 1e147117,
aa 11.1g7=33 PUS Is
� EFer
II uFeGSV.aan0
c.AlePNei r0 ..W4 16 paep 44ateeNf
03 C CHWACK 0E4 eaA 40 xµ015000
15 CL3771n°M r
o OWL 1 73,,
11 aelllTtLet I31f9
E pol 500T
]e DES PERES
fr EnafasaN
3e 115317071
Ew AA
w`uW"08051E°
snfE1
y0 5'RNNO caunrar
�41PW▪ B ri."511
00 PNe!
32 m 1.P� a4 �p+u4•
fa LAP, i TS 0.517114 FLOE MU 5
34 e0 30Pm tr." +4LE
Se Re1YNaons ee WCIVEn (MOM
57 et xwwEE�u'rswwrul
Tax
01 ▪ °e0ESM12R
41 e300110N 1Eee30E
eL QI0Wrc
44 ,f
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
MUNICIPALITIES IN THE MSD SERVICE AREA
environmental services
Figure No. 1—I
" C H 2 M - H i l l w i t h A A I - C a m p b e l l , a n d
" M o n t g o m e r y W a t s o n .
T h e c o n s u l t a n t t e a m s w i l l a s s i s t M S D w i t h t h e f o r m u l a t i o n o f a c o m p r e h e n s i v e S S M I P t o
f u l f i l l t h e g o a l s o u t l i n e d i n t h e M i s s i o n S t a t e m e n t . T h e S S M I P w i l l p r o v i d e a c o o r d i n a t e d
p l a n t o a d d r e s s e x i s t i n g p r o b l e m s a n d t o p r o v i d e g u i d a n c e f o r n e w d e v e l o p m e n t .
1 . 3 P H A S E I R E P O R T V O L U M E S
P h a s e I o f t h e S S M I P c o m m e n c e d i n O c t o b e r 1 9 9 4 p r o d u c e d s e v e r a l p r o d u c t s t o b e u s e d i n
i m p l e m e n t i n g M S D ' s s t o r m w a t e r m a n a g e m e n t p r o g r a m .
" W a t e r s h e d D a t a A s s e s s m e n t R e p o r t - a s u m m a r y o f t h e q u a l i t y a n d a d e q u a c y
o f a v a i l a b l e a n d r e q u i r e d s t o r m w a t e r d a t a f o r t h e p r e p a r a t i o n o f t h e w a t e r s h e d
p l a n s .
" P o l i c y a n d S t a n d a r d s R e p o r t - a r e v i e w a n d e v a l u a t i o n o f e x i s t i n g s t a n d a r d s ,
c r i t e r i a a n d m a j o r s t o r m w a t e r i s s u e s , w i t h r e c o m m e n d a t i o n s f o r m o d i f i c a t i o n s
n e c e s s a r y t o i m p l e m e n t a c o m p r e h e n s i v e s t o r m w a t e r m a n a g e m e n t p r o g r a m .
" W a t e r s h e d P l a n n i n g F r a m e w o r k R e p o r t - a s u m m a r y o f t e c h n i c a l a n a l y s i s
p r o c e d u r e s , m e t h o d o l o g y a n d g u i d a n c e f o r p r e p a r i n g t h e w a t e r s h e d m a s t e r
p l a n s .
1 . 4 H A E I T R M W A T E R M M l ' r i b E
D u r i n g P h a s e I , t h r e e c o m m i t t e e s w e r e f o r m e d t o g u i d e t h e S S M I P p r o c e s s a n d i n i t i a t e t h e
p u b l i c i n v o l v e m e n t n e c e s s a r y t o i m p l e m e n t a s u c c e s s f u l s t o r m w a t e r p r o g r a m .
" T h e S t o r m w a t e r S t e e r i n g C o m m i t t e e ( S S C ) i n c l u d e d M S D s t a f f i n v o l v e d i n
I : 8 1 O S - 0 0 1 \ s t l o u \ s e c d o n l
s t o r m w a t e r a n d t h e t h r e e c o n s u l t a n t t e a m s .
1 - 7
" T h e T e c h n i c a l A d v i s o r y C o m m i t t e e ( T A C ) c o n s i s t e d o f r e p r e s e n t a t i v e s o f t h e
l o c a l t e c h n i c a l c o m m u n i t y i n v o l v e d w i t h s t o r m w a t e r m a n a g e m e n t . T h e
c o m m i t t e e i n c l u d e d t h e f o l l o w i n g m e m b e r s :
N a m e O r g a n i z a t i o n T i t l e / P o s i t i o n
M i c h a e l G e i s e l C i t y o f C h e s t e r f i e l d D i r e c t o r o f P u b l i c W o r k s
L o u i s J e a r l s C i t y o f F l o r i s s a n t D i r e c t o r o f P u b l i c W o r k s
W i l l i a m H a w n S t e r l i n g C o m p a n y V i c e P r e s i d e n t
D o n S p e n c e r S t . L o u i s C o u n t y A s s i s t a n t D i r e c t o r o f H i g h w a y s
a n d T r a f f i c D e p a r t m e n t
J o s e p h E b e r t C i t y o f S t . L o u i s S e n i o r P r o j e c t E n g i n e e r
B i l l L u t h A s s o c i a t e d G e n e r a l S i t e U t i l i t y C o m m i t t e e
C o n t r a c t o r s
D r . P a u l M u n g e r
M i k e F u h r
U n i v e r s i t y o f M i s s o u r i P r o f e s s o r o f H y d r a u l i c s
M i s s o u r i D e p a r t m e n t A q u a t i c S e r v i c e s B i o l o g i s t
o f C o n s e r v a t i o n
G a r y D y h o u s e U S A r m y C o r p s o f C h i e f o f H y d r o l o g i c
E n g i n e e r s E n g i n e e r i n g B r a n c h
" T h e P u b l i c A d v i s o r y C o m m i t t e e ( P A C ) c o n s i s t e d o f r e p r e s e n t a t i v e s o f c o n c e r n e d
c i t i z e n s g r o u p s a n d l o c a l c o m m u n i t y l e a d e r s . T h e c o m m i t t e e i n c l u d e d t h e
f o l l o w i n g m e m b e r s :
N a m e
O r g a n i z a t i o n T i t l e / P o s i t i o n
J a m e s S h r e w s b u r y C i t y o f S t . L o u i s B o a r d o f A l d e r m e n
T o n y M o n a c o C i t y o f G l e n d a l e M a y o r
G e n e S t u m p f , I I I H o m e B u i l d e r s A s s o c . C h a i r m a n o f E n v i r o n m e n t
C o m m i t t e e
S a n d y R o t h c h i l d M i s s o u r i G r o w t h A s s o c . E x e c u t i v e D i r e c t o r
L " 8 1 0 8 - 0 0 1 \ s t l o u \ s e c t i o n I
1 - 8
Bruce Hollinger
Doug Woodruff
Olivia McKinney
Mary Brown
Deborah Kersting
Anthony Soukenik
Suzanne Hoffman
Anson Eickhorst
Logan Mayfield
Vickie Bessinger
Monsanto Corporation Manager of Utilities
Boatmen's Community President
Development Corporation
League of Women Voters
League of Women Voters
St. Louis County Council Councilwoman
Community Association Attorney
Institute
Coalition for the
Environment
US Army Corps of
Engineers
Board of Directors
Subdivision Trustee
Subdivision Trustee
The following individuals also served as substitute members when one of the above
committee members was absent: Al Owen from McDonnell -Douglass Corporation, Owen
Dutt from the U.S. Army Corps of Engineers, and Tim Fischesser from the St. Louis County
Municipal League.
The TAC and PAC discussed a number of technical and policy issues relating to existing
stormwater problems or potential changes to facilitate improved stormwater services in the
future. Input from the TAC and PAC has been incorporated into the conclusions and
recommendations presented in this report.
1.5 REPORT ORGANIZATION AND METHODOLOGY
This document is the Policy and Standards Report and is one of several volumes produced as
a part of Phase I of the SSMIP. The purpose of this document is to assess stormwater needs
and issues related to MSD policy and the overall goals of the SSMIP. Recommendations are
included for changes to existing policy and standards that are necessary to address the
L•8108-001\sIou\sectlonl
1-9
stormwater needs and issues for the MSD service area. This section explains the organization
of this report, the methodology and how this report fits into the overall implementation of
the SSMIP.
Section 1 of this report presents introductory material, general background, purpose, legal
authority, responsibilities, organizational information and identified stormwater needs and
issues. In Section 2, the current District stormwater program is assessed for each of the
major responsibility areas (Regulations and Standards, Engineering, Operation and
Maintenance, Capital Improvements and Funding). Section 3 discusses the issues related to
implementation of SSMIP recommendations. This report focuses on flooding and erosion
issues related to the drainage system and does not address the sanitary sewer system nor
does it provide in-depth consideration of water quality issues.
All three committees (TAC, PAC, and SSC) identified issues and problems with current
policies and standards and potential solutions. The three engineering consultant teams were
responsible for assessing the issues and problems, comparing policies to other urban areas,
documenting potential solutions and approaches and then making preliminary
recommendations on MSD policies and standards. The SSC reviewed the consultant
recommendations and made modifications as necessary. Policy and standards
recommendations were then presented to the TAC & PAC for feedback, and modifications
were once again made as necessary. This Policy and Standards (P&S) Report is a summary
of the discussions and decisions that resulted from this process.
The stormwater management policies presented in this report will be tested and verified in
the pilot watershed plans and then implemented as a part of the SSMIP. For major policy
decisions, stormwater program information from other major urban areas were used for
comparison including: Cincinnati, Milwaukee, Des Moines, Chicago, Jacksonville, and
Denver. In addition, questionnaires were sent to all local municipalities and interviews were
conducted with District personnel and representative communities to assess their
understanding and expectations of the District's role in stormwater management. The roles
of the local municipalities, the County, and various agencies involved with stormwater
management were identified to differentiate the appropriate jurisdictional level for
1:8108.001\stIou\section'
1-10
implementation of stormwater management responsibilities. The information obtained from
the County and local municipalities was considered in the assessment of the current District
stormwater program and the policy and standards recommendations.
The recommendations contained in this report will help guide the preparation of specific
watershed plans to be completed in subsequent phases as they pertain to policy type issues.
This document will also be used to guide stormwater related revisions to the MSD Rules and
Regulations and in preparation of a model stormwater ordinance for the local municipalities.
The final implementation of this document will be the adoption of stormwater master plans
for each watershed and in stormwater ordinances passed by the MSD Board and local
municipalities.
1.6 STUDY AREA PHYSICAL DESCRIPTION
The MSD service area includes tributary areas to three major river basins -- the Missouri, the
Meramec, and the Mississippi. Figure 1-2 presents the 25 watersheds delineated by the
District and the primary stormwater management system (PSWMS) which comprises the
rivers, streams, canals, ditches, culverts, storm, and combined sewers that have a tributary
area generally greater than 150 acres in developed areas and 400 acres in undeveloped areas.
Ground elevations in the area range from 383 feet to 903 feet NGVD with wide riverine
floodplains along the Missouri and Mississippi. Headwater areas are characterized by
forested hills with relatively steep channel slopes. Soils tend to be clay to silty clay with
portions of the watersheds characterized by Karst topography with sinkholes.
Urbanization of the area has proceeded from east to west from the City of St. Louis in the
eastern portion of the service area along the west bank of the Mississippi. Much of the City
of St. Louis and of the adjacent municipalities combine sanitary and storm flows while the
developing areas have separate storm sewer systems. Land use characteristics for the St.
Louis Metro Region as provided by the East West Gateway Coordinating Council are 42.7
percent residential, 6.8 percent commercial, 3.9 percent industrial, 0.6 percent extractive
(mining), 6.5 percent public, 8.3 percent recreational, 0.6 percent transportation, and 30.6
1:813&{41\stlou\sec ionl
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
WATERSHEDS IN THE MSD SERVICE AREA
environmental services
Figure No. 1-2
percent undeveloped. Physical descriptions of the respective watersheds in the study area
are contained in the Watershed Data Assessment Report.
1.7 DISTRICT PURPOSE AND ORGANIZATION
MSD was established as a metropolitan sewer district pursuant to a Plan adopted in a special
election in 1954. The Plan established the District in the interest of public health and for the
purpose of providing adequate sewer and drainage facilities within its boundaries. The
District is organized pursuant to Article IV, Section 30 of the Missouri Constitution which
enables the formation of "a metropolitan district for the functional administration of services
common to the area." As such, the District is a political subdivision of the State of Missouri.
Prior the formation of the District, the City of St. Louis, various municipalities and private
sewer companies provided sewer service which collected sewer waters and transported them
to nearby rivers and streams. The Plan empowers the District with jurisdiction over sanitary
sewer and drainage systems and facilities within its boundaries and charges the District to
maintain, operate, reconstruct and improve a comprehensive sewer and drainage system to
protect public health and welfare.
Figure 1-3 presents the overall organizational structure of the District including the major
service divisions that are involved in the formulation of the SSMIP. A broad cross-section of
MSD Departments are associatied with providing stormwater management services and
participated in the SSMIP process including Financial, Engineering, Maintenance,
Communications and Legal. The SSMIP engineering consultant teams worked under the
direction of the Engineering Division.
1.8 DISTRICT LEGAL AUTHORITY AND RESPQN. IBILITIFS
MSD's authority is generally outlined in the Plan of the Metropolitan St. Louis Sewer District
(PIan) which was passed by special election in 1954. The constitutionality of the Plan was
upheld by the Missouri Supreme Court in State of Missouri ex inf. John M. Dalton, Attorney
1:SIO8-00l\suou\sectionl
1-13
r
II
MSD Departments and Offices Involved In the Storm wa ter
System. Master Improvement Plan
l
Board of Trustees
Executive Director
And
Asst. Executive
Director
Administration
Communications
Finance
f
Personnel
Capital Improvements
Compliance Projects
Construction
Legal
Engineering
immummal
I
I
Operations
Maintenance
Environmental
Compliance
M
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
MSD DEPARTMENTS AND OFFICES INVOLVED IN THE
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN ISS MIP)
environmental services
Figure No. 1-3
General v. the Metropolitan St. Louis Sewer District, 275 S.W. 2d 225. The Plan grants MSD
jurisdiction, control, possession and supervision of all facilities for the collection and disposal
of sanitary sewage and stormwater within its boundaries. Responsibilities of MSD, as
specified in the Plan, include preparation of design standards; providing engineering
functions related to planning, design, construction observation and new development plan
review and permitting; conducting operations and maintenance; and constructing capital
improvements. Table 1-1 summarizes the primary stormwater-related responsibilities and
powers of MSD. These powers are grouped according to the major responsibility areas that
are used as the major sub -section headings in Section 2.
In addition to the specifically enumerated powers of the District, general powers are granted
to the District that may be necessary for the District to carry out its purpose. The Plan states,
"No enumeration of powers in this Plan shall operate to restrict the meaning of this general grant of
power or to exclude other powers comprehended within this general grant." The powers granted to
MSD for management of stormwater are broad and generally sufficient to enact a
comprehensive stormwater management program. Nonetheless, certain aspects of
stormwater management are not under the authority of MSD because they are not
enumerated in the Plan or because MSD has chosen not to exercise authority in these areas.
MSD does not have legal authority to establish review and enforce grading standards nor to
establish review and enforce zoning and land use standards. MSD has some degree of legal
authority in the areas of floodplain regulation, stormwater quality, erosion and sediment
control, but MSD does not exercise it. This authority is not exercised because other agencies
have accepted this responsibility or other levels of government are more appropriate for
enforcement, or because the Plan is not definitive as to the extent of legal authority.
1.9 NEEDS. PJQBLEMS AIJD ISSUES
Information received from MSD, representatives of the technical community, and general
public indicated a number of major storrnwater concerns. Table 1-2 presents a summary of
priority issues raised by the TAC and PAC responding to a survey developed by MSD. In
M168-001 \ stiou \ secrionl
1-15
Table 1-1
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
MSD Responsibility Areas and Powers for Stormwater Management
Responsibility Area Powers
Regulations and Standards • Adopt ordinances and regulations to carry out the
Plan
Engineering
• Establish building or floodway reservation lines along
streams
• Approve, revise or reject plans and designs of
stormwater facilities (including inspection and
supervision by the District)
• Prepare, revise and adopt plans, designs and cost
estimates of drainage systems
• Permit the connection to and use of District facilities
• Enforce and seek penalties for violation of District
ordinances through the courts
• Police and enforce building or floodway reservation
lines to maintain the natural and healthful flow of
streams
Operation and Maintenance • Maintain, operate and reconstruct a comprehensive
drainage system
Capital Improvements • Construct additions, improvements or extensions to
the drainage system
Funding • Establish rates or other charges from real property
served by the District
1:810&-0O1\sdou\sedionl
• Fix, levy and collect special benefit assessments for
drainage system improvements
• Incur debt and issue bonds
• Contract with municipalities or other agencies for
construction, use or maintenance of the storm system
1-16
Table 1-2, priority issues are grouped into the following categories: Regulations and
Standards, Funding and Financial, Maintenance and Inspection, Existing Problems,
Institutional, and Public Involvement. For the TAC committee, most issues fell under
Regulations and Standards with Maintenance and Inspection and then Existing Problems
being the next most important. For the PAC, Funding and Financial was the category with
the largest number of issues raised. Institutional and then Regulations and Standards were
the next most important in terms of number of issues raised by the PAC. Table 1-2 and
subsequent discussions with the SSC, TAC and PAC were used to compile the following list
of issues that are grouped into the following categories: Institutional, Technical,
Maintenance, Funding, and Public Relations. The source of the issue is indicated in
parentheses according to the committees (TAC, PAC, SSC) that brought forward the issue in
initial discussions of needs and issues,
Institutional
1. Define the stormwater management responsibility and authority of the various
government jurisdictions within the District including grading and other "backyard"
issues. (SSC, TAC, PAC)
2. Require all development and redevelopment projects to be designed and constructed in
accordance with District drainage policy, criteria and standards. Require approval of
plans for compliance with drainage criteria prior to issuing permits. (SSC)
3. Require Iocal community adoption (or implementation) of District drainage design
criteria and standards. (SSC)
4. Require strict compliance and enforcement of District stormwater management policies,
criteria and standards. (SSC)
Technical
1. Adopt a design/overflow (or major/minor) system approach for all future drainage
improvements to provide an improved level of protection. (SSC)
I:B168-OO1\sUou\sectionl
1-17
TABLE 1-2
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
PAC and TAC Priority stormwater Issues
Notes:
1. Each *equals one response from a Public Advisory Committee (PAC) or Technical Advisory Committee (TAC) member for that stormwater issue
2. Weighted Priority Score equals a sum of point values for each response (1st priority=6 points...6th priority=1 point)
3. Unweighted Priority Score equals a sum of responses for that issue (All priority rankings (1st- 6th) = 1 point)
Stormwater
Issue
Category
Issue
#
Description of Stormwater Issues
Priority
1st
by
2nd
Rankings
PAC
3rd
members
4th
assigned
5th
6th
Weighted
Priority
Score
Unweighted
Priority
Score
Priority
1st
by
2nd
Rankings
TAC
3rd
members
4th
assigned
5th
6th
Weighted
Priority
Score
Unweighted
Priority
Score
Regulations
& Standards
RS-1
Revise/update design criteria (specific areas listed:
detention basins, runoff calculation, review process,
construction materials
"
*
8
2
**
*
4
22
5
RS-2
Evaluate existing level of protection in CSO area
0
0
•
6
1
RS-3
Determine the proper level of protection and/or
treatment level for stormwater
*
6
1
0
0
RS-4
Determine design criteria on watershed or District -
wide basis?
*
4
1
•
8
2
RS-5
Evaluate regional vs. on site detention
*
4
1
*
4
1
RS-6
Add erosion control review and enforcement
*
1
1
*
*
*
9
3
RS-7
Develop design/overflow (minor/major) design
criteria to accommodate large storms
0
0
*
5
1
RS-8
Evaluate if detention requirements are appropriate
for highly developed areas
0
0
1
1
RS-9
Establish buffer zone/setbacks for maintenance and
protection against erosion and meandering
*
2
1
*
5
2
RS-10
Meeting EPA regulations
0
0
"
1
1
TOTAL
25
7
61
17
Funding Sr
Financial
FF-1
Determine funding needed for complete MSD
stormwater program (Including annexed area)
*
*
4
2
0
0
FF-2
Establish equitable funding mechanism/ source for
complete MSD stormwater program
*
**
**
**
24
7
_
*
*
7
2
FF-3
Revise escrow procedures to eliminate redundancy
0
0
*
5
1
FF4
Rate determination and structure
•
*
8
2
0
0
FF-5
Avoid rate shock and imposition of undue financial
burdens
*
1
1
0
0
FF-6
Establish stormwater matching funds or Ioans for
residential and municipal improvements
•
•
4
2
*
3
1
FF-7
Should financing be on a watershed or District wide
basis
*
3
1
0
0
TOTAL
44
15
15
4
Maintenance
& Inspection
MI-1
Establish maintenance of stormwater facilities in the
Annexed Areas
4
1
*
7
2
PAC6153.XLS
Page 1 of 2
10/2/95 5:47PM
TABLE 1-2
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
PAC and TAC Priority Stormwater Issues
Notes:
1. Each * equals one response from a Public Advisory Committee (PAC) or Technical Advisory Committee (TAC) member for that stormwater issue
2. Weighted Priority Score equals a sum of point values for each response (1st priority=6 points...6th priority=1 point)
3. Unweighted Priority Score equals a sum of responses for that issue (All priority rankings (1st- 6th) =1 point)
Stormwater
Issue
Category
Issue
!!
Description of Stormwater Issues
Priority
1st
by
2nd
Rankings
PAC
3rd
members
4th
assigned
5th
6th
Weighted
Priority
Score
Unweighted
Priority
Score
Priority
1st
by
2nd
Rankings
TAC
3rd
members
4th
assigned
5th
6th
Weighted
Priority
Score
Unweighted
Priority
Score
MI-2
Determine and provide appropriate preventative
maintenance and inspection
*
1
1
*
1
1
MI-3
Provide maintenance or standards for upkeep of
detention facilities
*
_ 6
1
*
*
*
11
3
MI-4
Evaluate current maintenance practices
0
0
3
1
M1-5
Improve response time on maintenance work
0
0
*
4
1
MI-6
Assess conditions of existing stormwater facilities
1
1
0
TOTAL
12
4
26
8
Existing
Problems
EP-1
Prioritize areas where repair or upgrade is needed
most
•
2
1
*
2
1
EP-2
Sanitary backups related to flooding
0
0
*
2
1
EP-3
Alleviate current flooding
*
6
1
*
*
7
2
EP-4
Channel improvements to control erosion
0
0
*
*
*
15
3
TOTAL
8
2
26
7
Institutional
1-1
Concentrate responsibility for stormwater into one
agency
•
*
8
2
0
0
1-2
MSD to interface with other agencies like Dept. of
Conservation
*
4
1
0
0
I-3
Define responsibility of MSD, property owners, and
other governmental agencies for stormwater
**
***
*
31
6
0
0
1-4
MSD involvement in zoning to assure proper
watershed control
*
2
1
0
0
TOTAL
95
10
0
0
Public
Involvement
PI-1
Convincing public of needs and required funding
**
*
12
3
*
5
1
PI-2
Establish "House Sewer Lateral Insurance Program"
0
0
*
2
1
PI-3
Educate developers on their stormwater impacts and
their mitigation responsibility
0
0
*
6
1
TOTAL
12
3
13
3
PAC6153.XLS
Page 2 of 2
l0/2/95 5;47PM
2. Establish runoff control requirements by watershed based on existing or planned
watershed capacities to mitigate impacts of new development or redevelopment. (SSC)
3. Require stormwater controls that limit flows to established system capacities at the most
appropriate site -specific or local level. (SSC)
4. Identify potential regional detention sites to improve the efficiency and cost effectiveness
of detention in each watershed where appropriate. (SSC)
5. Designate setbacks adjacent to drainage system components such as channels and
streams to reduce the impacts of flooding and erosion. (SSC)
6. Develop a capital improvement program which identifies and prioritizes all major capital
improvements for each watershed. (SSC)
7. Regulate future development in the floodplain consistent with applicable, local, state and
federal regulations. (SSC)
8. Encourage voluntary incorporation of water quality components into overall stormwater
management improvements. (SSC)
9. Define the preferred materials for channel linings for which MSD will accept
maintenance responsibility for the improvement. (TAC)
10. Define when channels should be enclosed versus leaving them as open channels. (TAC)
11. Provide training on the application of District policies and standards. (TAC)
12. Determine when full -flow pipe design assumptions are not accurate. (TAC)
13. Provide standards that account for the benefit of detention ponds in design of
downstream pipe sizes. (TAC)
I:S1O8-OO1\5uou\section1
1-20
14. Provide standards that establish consistency between municipal and District reviews.
(TAC)
15. Set a policy for the regulation/control of drainage way easements. (TAC)
16. Insure that drainage facilities are built according to plans and are reviewed/approved by
providing adequate inspection manpower and qualified construction inspectors (perhaps
Non -District). (TAC)
17. Provide construction inspections that verify grading of detention facilities and grading of
"overflow" drainage system (swales, etc.). (TAC)
18. Apply drainage standards consistently. (PAC)
19. Provide standards and/or enforcement for erosion and sediment control during
development activities. (PAC)
20. Provide adequate means for enforcing all of the District's standards. (PAC)
21. Provide additional technical support to the public on drainage issues. (PAC)
Maintenance
1. Provide regular, planned maintenance of all dedicated and MSD-accepted drainage
facilities in public rights -of -way or easements. (SSC)
2. Require covenants or other agreements for maintenance of all non -District stormwater
facilities which discharge to MSD's system. (SSC)
3. Provide maintenance in annexed areas. (TAC and PAC)
I:18108-0011p&s0706.wpc
1-21
4. Define maintenance responsibility and standards for 'backyard" drainage problems.
(TAC)
5. Define maintenance responsibility and/or provide a maintenance registration (or
contract) for detention ponds. (TAC and PAC)
6. Provide a method for accountability and follow-up on complaints and reported
problems. (PAC)
Funding
1. Implement a funding mechanism to recover the administrative and maintenance costs of
providing stormwater services according to causative factors. (SSC)
2. Identify a method to fund capital improvements which fairly and equitably allocates
costs according to causative factors. (SSC)
3. Collect reasonable fees to recover costs associated with stormwater plan reviews and
inspections. (SSC)
4. Provide adequate funding for executing full MSD stormwater services including
problem/complaint resolution. (TAC)
5. Coordinate escrow policies between MSD and local municipalities to eliminate
redundant escrows. (TAC)
6. Provide a funding mechanism that is readily understandable for the general public.
(PAC)
I:1810 8-00I Ip&s0706.wpc
1-22
Public Relations
1. Implement an aggressive public information and involvement program to promote both
the quantity and quality aspects of stormwater management and to obtain feedback in
developing recommended improvements. (SSC)
2. Implement a more proactive public information and involvement program for
stormwater management and to obtain feedback in developing recommended
improvements. (TAC)
3. Provide guidance to sub -division trustees on their responsibility and necessary
maintenance procedures for detention basins. (TAC)
4. Provide education that underscores the need to preserve drainage easements. (TAC)
5. Provide a maintenance handbook that gives the details of maintenance activities and
schedules that should be conducted by the general public. (PAC)
6. Establish a hotline to receive public questions and reports on drainage issues. (PAC)
7. Establish more public relations activities. (PAC)
Resolution of these issues can be directly linked to MSD's authority to provide stormwater
service within the District. Each of the major issue categories on the list fall under one of
MSD's areas of responsibility (Design Standards; Engineering; Operation and Maintenance;
and Capital Improvements) or are tied to Funding or Public Involvement and Information
(PI&I).
The Institutional issues are primarily related to who has authority and responsibility to
provide stormwater services. A fundamental need that was identified was to clearly define
authority, responsibilities and requirements among MSD, the County and the municipalities.
The institutional issues relate to Design Standards, Engineering and Operation and
I:18108-0011p&s0706. wpc
1-23
Maintenance, and these issues are addressed for each of these major responsibility areas in
Section 2. Other institutional issues relate to implementation or enforcement of MSD rules
and regulations which are addressed in Section 3.
The Technical issues involve primarily Regulations and Standards, with some relating to
MSDs Engineering responsibilities. Major technical issues such as the Ievel of protection,
methods for sizing pipes and the approach for sizing detention basins are addressed in detail
under the Regulations and Standards in Section 2.2. Many of the other technical issues are of
a "detailed" nature that can be incorporated into a future revision of MSD's "Rules and
Regulations" or modifications to the way MSD conducts its reviews. Other technical issues
are addressed with Capital Improvements in Section 2.5 or in the Watershed Planning
Framework Report.
Maintenance was a major issue that related to the responsibility for maintenance, and the fact
that maintenance was not performed at an acceptable level. The Operation and Maintenance
discussion (Section 2.4) specifically addressees the responsibility issue, while the Funding
section examines the need for a funding source to provide maintenance where and when it is
needed.
The Funding issues will be addressed in Section 2.6. This section identifies both funding
sources and mechanisms to pay for maintenance and capital improvements. Inadequate
funding and staffing are the underlying reasons for many of the stormwater problems/issues
experienced across the District.
Stormwater public relations have not been a past priority of MSD, which is confirmed in
several of the identified issues. Similar to funding, the lack of public relations, education and
information dissemination is another underlying cause of some of the problems/issues facing
MSD. A separate Public Information & Involvement (PI&I) plan is being prepared by MSD
to address these issues.
1:18108.00 l 1p&s0706.wpc
1-24
Maintenance, and these issues are addressed for each of these major responsibility areas in
Section 2. Other institutional issues relate to implementation or enforcement of MSD rules
and regulations which are addressed in Section 3.
The Technical issues involve primarily Regulations and Standards, with some relating to
MSDs Engineering responsibilities. Major technical issues such as the level of protection,
methods for sizing pipes and the approach for sizing detention basins are addressed in detail
under the Regulations and Standards in Section 2.2. Many of the other technical issues are of
a "detailed" nature that can be incorporated into a future revision of MSD's "Rules and
Regulations" or modifications to the way MSD conducts its reviews. Other technical issues
are addressed with Capital Improvements in Section 2.5 or in the Watershed Planning
Framework Report.
Maintenance was a major issue that related to the responsibility for maintenance, and the fact
that maintenance was not performed at an acceptable level. The Operation and Maintenance
discussion (Section 2.4) specifically addressees the responsibility issue, while the Funding
section examines the need for a funding source to provide maintenance where and when it is
needed.
The Funding issues will be addressed in Section 2.6. This section identifies both funding
sources and mechanisms to pay for maintenance and capital improvements. Inadequate
funding and staffing are the underlying reasons for many of the stormwater problems/issues
experienced across the District.
Stormwater public relations have not been a past priority of MSD, which is confirmed in
several of the identified issues. Similar to funding, the lack of public relations, education and
information dissemination is another underlying cause of some of the problems/issues facing
MSD. A separate Public Information & Involvement (PI&I) plan is being prepared by MSD
to address these issues.
1:18108-0011p&50706.wpc
1-24
In addition to the list of general needs and issues in this section, the Watershed Assessment
Report lists specific needs and problems associated with erosion and flooding for each
individual watershed.
I:18108-0011p&s0706. wpc
1-25
2.0 ASSESSMENT OF EXISTING STORMWATER MANAGEMENT PROGRAM
2.1 INTRODUCTION
Developments of a comprehensive stormwater management program must begin with an
assessment of the existing program in terms of what services are currently provided and then
what services and level of service should be provided by the MSD. In the following sections,
current MSD services, policies and standards are assessed for each of the major responsibility
areas in a stormwater management program including: Regulations and Standards (Section
2.2); Engineering (Section 2.3); Operation and Maintenance (Section 2.4); Capital
Improvements (Section 2.5); Funding(Section 2.6).
The assessments consist of some or all of the following components:
• Defining an objective/purpose for MSD policy and standards
• Describing the existing conditions/program
• Establishing the problems needs and issues
• Developing and evaluating options and examples
• Presenting recommendations
MSD has the authority to provide stormwater services throughout the service area. The
previous section recognized issues and problems associated with the current level of service
and identified a number of needs and areas where service could be improved or expanded.
MSD has specific authority for the following tasks: to establish regulations and standards for
stormwater control; to provide engineering functions that relate to stormwater such as a
review of development plans, construction inspection, and planning and design of drainage
problem resolution; to conduct operations and maintenance on stormwater facilities; and to
construct capital improvements. Sections 2.2 through 2.5 assess MSD policy and standards
1:8106-00lss[Jouis's Ction2
2-1
with respect to the above tasks. Where deficiencies or problems exist, specific
recommendations are presented to achieve the desired level of service for the stormwater
management program.
An important factor in MSD's ability to carry out its stormwater management program is its
ability to fund the required stormwater services and improvements. Section 2.6 considers
various funding sources and mechanisms available to MSD and recommends an appropriate
funding program for the District.
I:8 1O8-00Itst.iouisluction2
2-2
2.2 REGULATIONS AND STANDARDS
The Plan specifically gives MSD the legal authority to adopt ordinances and rules associated
with providing stormwater services across the District. Those ordinances and rules serve as
the enforcement mechanism to carry out the stormwater management program of the
District. Various regulations and standards provided in the ordinances and rules serve as the
legal framework and technical tools as well as the basis for evaluating compliance with MSD
stormwater policy.
The primary source for stormwater regulations and standards in the District is The
Metropolitan St. Louis Sewer District Rules and Regulations and Engineering Design Requirements
for Sanitary Sewage and Stormwater Drainage Facilities (Rules and Regulations). This document
was adopted by Ordinance 7691 in 1989 to be the official governing document for sanitary
and stormwater facilities within MSD boundaries. The Rules and Regulations detail the
minimum requirements for the design and construction of storm sewers and detention
facilities including permitted construction materials, methods, design rainfall and runoff data,
hydraulic Ioss assumptions, and acceptable formulae and methodologies. Special
requirements are outlined to provide facilities that drain sinkhole areas that are to be
developed. Floodplain requirements are also outlined regarding minimum elevations for
structures, allowable velocity increases, and acceptable methodologies for an engineer's
floodplain assessment. The MSD rules are in some cases supplemented by more
comprehensive local rules or regulations.
During Phase I of the SSMIP, a number of the stormwater policy issues were identified and
discussed, including:
• Level of protection
• Flow/storage methodology
• Release rate and detention basin criteria
• Floodplain requirements
• Development site erosion and sediment control
11108-001Lsl ]auislecuon2
2-3
" W a t e r q u a l i t y
" C h a n n e l t r e a t m e n t
O n e o f t h e s e , I e v e l o f p r o t e c t i o n , w a s d i s c u s s e d a t l e n g t h w i t h t h e S S C , T A C a n d P A C
b e c a u s e o f t h e p o t e n t i a l i m p a c t s o n d e v e l o p m e n t a n d t h e o v e r a l l p e r f o r m a n c e o f t h e
s t o r m w a t e r s y s t e m .
T h i s s e c t i o n a d d r e s s e s t h e f o r m u l a t i o n o f M S D p o l i c y f o r e a c h o f t h e i s s u e s a n d r e l a t e d
p r o b l e m s . F o r e a c h p o l i c y i s s u e , a s p e c i f i c o b j e c t i v e i s d e f i n e d a s a c o m p o n e n t t o t h e o v e r a l l
s t o r m w a t e r p r o g r a m . T h e c u r r e n t p r o g r a m i s d i s c u s s e d a n d t h e n a s s e s s e d t o d e t e r m i n e
e x i s t i n g p r o b l e m s o r d i f f i c u l t i e s i n i m p l e m e n t i n g t h e o v e r a l l s t o r m w a t e r p r o g r a m . P o t e n t i a l
o p t i o n s a r e p r e s e n t e d l o n g w i t h s p e c i f i c p o l i c y r e c o m m e n d a t i o n s .
2 . 2 . 1 L E V E L O F P R O T E C T I O N
T h e e s t a b l i s h m e n t o f a l e v e l o f p r o t e c t i o n f o r t h e S S M I P i s i m p o r t a n t t o a s s u r e t h a t
i m p r o v e m e n t s t o t h e d r a i n a g e s y s t e m w i l l p r o v i d e a d e q u a t e p r o t e c t i o n t o r e s i d e n t i a l a n d
c o m m e r c i a l s t r u c t u r e s a n d t h e r o a d w a y s y s t e m d u r i n g f l o o d c o n d i t i o n s . T h e i n t e n t i s t o
p r o t e c t p u b l i c a n d p r i v a t e p r o p e r t y f r o m f l o o d w a t e r s d u r i n g t h e " d e s i g n " r a i n f a l l o r f l o o d i n g
e v e n t . I n t h e c a s e o f c o m m e r c i a l a n d r e s i d e n t i a l b u i l d i n g s , t h i s m e a n s t o d e s i g n s t r u c t u r e s s o
t h a t t h e y a r e s a f e f r o m d a m a g e a s a r e s u l t o f f l o o d i n g t h a t o c c u r s d u r i n g t h e d e s i g n e v e n t .
I n t h e c a s e o f r o a d s , s a f e p a s s a g e s h o u l d b e p r o v i d e d d u r i n g t h e d e s i g n e v e n t . S a f e p a s s a g e
m i g h t m e a n t h e n o r m a l f l o w o f t r a f f i c o r e m e r g e n c y a c c e s s . A u n i f o r m l e v e l o f p r o t e c t i o n i s
t y p i c a l l y p r o v i d e d f o r b u i l d i n g s , w h e r e a s t h e l e v e l o f p r o t e c t i o n f o r r o a d s m a y v a r y w i t h t h e
s i z e , t r a f f i c p a t t e r n s o r n e e d f o r e m e r g e n c y a c c e s s . O n c e a l e v e l o f p r o t e c t i o n h a s b e e n
s e l e c t e d , d r a i n a g e i m p r o v e m e n t s a r e s i z e d t o a c h i e v e t h a t l e v e l o f p r o t e c t i o n , b y d e s i g n i n g
c u l v e r t s , p i p e s , c h a n n e l s , a n d d e t e n t i o n b a s i n s t o b e l a r g e e n o u g h t o a c c o m m o d a t e t h e
a n t i c i p a t e d s t o r m w a t e r f l o w s a n d v o l u m e s f o r t h e d e s i g n e v e n t .
1 : 8 1 0 8 - 0 0 1 1 s t . l n u i s l u c t i o n 2
2 - 4
Objective
Select a level of protection from potential stormwater damages that is cost-effective, generally
consistent with standards from other urban areas, and acceptable to property owners in the
District.
Current Program
MSD currently has drainage related technical standards and criteria in place to guide the
development of drainage improvements. The current criteria require that drainage facilities
accommodate a design storm with a 15-year return interval (20-year return period in
combined sewer areas). A 15-year design storm is a rainfall event that would be expected to
occur on the average of once every 15 years. A 15-year level of protection means that the
drainage system, such as a ditch, culvert, or storm sewer, would be sized to pass the
stormwater flow expected from a 15-year rainfall event. There is no requirement to design or
check for any larger events such as the 100-year event.
Problem /Issue
With the current 15-year criteria, no protection is provided for storms that exceed this design
storm magnitude and flooding or erosion may result during those storms. That is, a 100-year
storm will exceed the capacity of the drainage system and will likely result in flooding and
erosion problems. The mission statement for the SSMTP states MSD's intention to resolve
existing stormwater problems throughout the District. With a 15-year design, MSD's
stormwater facilities will "fail" during events greater than a 15-year event. This can be a
major problem in that failure has resulted in serious flooding during periods of extreme
rainfall. A 15-year level of protection is "low" compared to many other urban areas. Table
2-1 presents stormwater quantity design criteria for a cross-section of the stormwater
requirements in several large urban areas across the country, many of which have adopted a
two -tiered system for conveying flows. This two -tiered system provides a "design"
component which corresponds to MSD's 15-year criteria and an "overflow" component to
I:8108-00 P. t.1ouIstsection2
2-5
Table 2-1
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Stormwater Quantity Design Criteria for Several Urban Areas
STORMWATER QUANTITY CRITERIA
Agency/Area
Overflow
System
Capacity
Design System
Capacity
Detention
Requirement
for Develop-
meet
Detention Release
Rate
Detention
Storage
Volume
Runoff
Volume
Requirement
No
Metro St. Louis
Sewer District
15 yr
(1)
15 yr
(1)
Yes
2, 5, 10, 15 yr
undeveloped (2)
To meet
release rate
Lake Co., IL
100 yr
100 yr or 10 yr
(3)
Yes
100 yr- 0.15 cfs/ac
2 yr- .04 cfs/ac
2 , 100 yr
No
Jacksonville, FL
100 yr
5 yr
Yes
10, 25, 100 yr
Pre -development
10, 25,
100 yr
Yes
Austin, TX
100 yr
25 yr
Yes
100, 25, 10, 5, 2 yr
Pre -development
To meet
release rate
No
Fairfax County, VA
100 yr
developed
condtions
25 yr- primary
roads, 10 yr-
other roads and
structures
Yes
2 yr and 10 yr
Pre -development
To meet
release rate
No
Denver
UDFCD Metro
Communities (4)
100 yr
5 yr
Yes
100 yr- 1.0 cfs/ac
10 yr- 0.3 cfs/ac
10, 100 yr
No
Milwaukee MSD
100 yr
5, 10 yr
Varies
Less than down -
stream capacity
100 yr
No
Tulsa, OK
100 yr
5 yr
Yes
5, 100 yr
100 yr
No
Las Vegas, NV
100 yr
10 yr
No
No Requirement
No
Requirement
No
Rice Creek Watershed
District, MN
100 yr
N/A
Yes
1 yr and 100 yr
Pre -development (4)
2. 100 yr
No
(1) 20 yr for combined sewers
(2) Basins are designed to release at undeveloped rates for 2 yr, 5 yr, 10 yr, and 15 yr design storms
in St. Louis County; 2, 5, 10, and 20 yr in the City of St. Louis.
(3) 100 yr capacity is required for drainage areas greater than 20 acres.
The County prefers that the 100 yr flow is conveyed in open channels.
(4) Depending on location some subwatersheds do not have rate control if they are near the Mississippi River.
2-6
STRMQUN1.XIS
10/2195 07:08
pass a larger event, typically the 100-year event. The "design" components of the drainage
system includes the inlets, pipes, storm sewers and ditches that function during typical
rainfall events. The "overflow" system comprises the major overflow routes such as swales,
streets, floodplains, detention basins, and natural overflow, and ponding areas. Existing
MSD rules do not require an overflow system or a 100-year level of protection.
Adoption of the 100-year event as the level of protection standard was first widely promoted
in the Water Resources Council's Flood Hazard Evaluation Guidelines for Federal Executive
Agencies. The standard for the 100-year base flood was formalized as an integral part of the
National Flood Insurance Act of 1968. This act was designed to reduce economic losses
caused by flooding which had been steadily on the rise since the 1930's despite billions of
dollars worth of structural flood projects. The 100-year flood is more accurately referred to
as the one percent probability flood, which means that there is a one percent chance that a
flood of equal or greater magnitude will occur in any given year. The one percent
probability standard was judged by federal agencies to reasonably "balance the desire to
avoid inordinate flood losses with the desire to avoid excessive regulation of development"
(Moore and Moore, 1989). A report prepared by the Federal Emergency Management
Agency (FEMA, 1983) viewed the 100-year base flood standard. The report, which was based
on surveys, evaluations, experiences, and comments of many affected agencies found strong
support for the existing policies including governors and state agencies. A 100-year level of
protection is the current "standard" for designing flood control and drainage facilities both
locally and nationally.
The issue associated with MSD's current level of protection is two -fold. First, an overall 15-
year level of protection offers a rather limited level of protection that has resulted in "failure"
of MSD facilities and stormwater flooding, causing both nuisances and damages. Second, a
15-year level of protection is not consistent with current 100-year floodplain regulations for
the area or with adopted levels of protection for comprehensive stormwater management
programs across the country.
k: B I08-ao Iuc.touisLuaionz
2-7
Potential Options and Solutions
One of the specific objectives identified in the SSMIP mission statement is "to provide a
uniform, cost-effective, and equitable level of protection " against stormwater related flooding
and erosion. The philosophy behind selection of the 100-year level of protection for
floodplain regulation indicates that a design standard of the 100-year event is most
appropriate for protecting development from stormwater flooding. The current 100-year
basis for regulating floodplains suggests the need to provide similar stormwater protection
to provide a uniform level of service across the District. These facts indicate a need for an
increased level of protection beyond the 15-year event to the 100-year event.
In adopting a new Ievel of protection, a decision must be made in terms of how that level of
protection will be provided. Although many other urban areas have adopted a 100-year
design, they do not require the "primary" or "minor" stormwater system, pipes, and channels
to pass the 100-year event. These components, which handle "every day" type rainfall events,
are typically sized to withstand a smaller event, ranging from the 5-year event to the 10-year
event with an overflow provided to accommodate the 100-year event. This concept for
designing the stormwater system is often referred to as the "major/minor" approach, or as
recommended by MSD staff, the "overflow/design" concept, which provides for an "overflow
system" to safely handle the major flows and volumes that may occur from infrequent floods
such as the 100-year flood or in these instances when the design system is obstructed by ice
or debris. The "design system" is a smaller capacity part of the overall drainage system that
is sized to handle more frequent and smaller flows, in this case the 15-year event. The
design system typically includes storm sewers, culverts and low flow channels, while the
overflow system comprises major overflow routes such as swales, streets, floodplains,
detention basins, and natural overflow in ponding areas. A 15-year level of protection for
the "minor" or "design" system provides a relatively high level of protection for the design
system compared to other programs around the country.
I:8 I0 8.00 I\st. ] o u islsectio n 2
2-8
Recommendations
(1) Adopt the "overflow/design" concept for all future drainage improvements.
(2) Adopt a 100-year level of protection for the "overflow system." This design standard
is consistent with many other communities and the National Flood Insurance
Program. In the case of detention basins, which must function as a component of the
overflow system, a 100-year standard is required to achieve the desired level of
protection. The adoption of the 100-year standard for sizing required storage volumes
in detention basins is also recommended.
(3)
Continue to use the 15-year level of protection for the criteria of the "design system"
(20-year level of protection for combined sewer area). Although the 15/20-year
standard is slightly more conservative than most other "design system" standards
across the country, the Phase I SSMIP Committees felt it was appropriate to continue
sizing storm sewers for a 15-year (20-year) design to this existing level of protection
uniformly throughout the Distract.
2.2.2 FLOW AND STORAGE METHODOLOGY
Appropriate technical procedures and techniques are necessary to design drainage facilities
for the St. Louis area. These procedures and techniques will be used by engineers and other
technical staff and must be consistent with the objectives of the SSMIP. Two of the most
important aspects in the design of stormwater facilities are the methodologies for
determining design flows and storage which directly affect the sizing of inlets, storm sewers,
and detention basins.
Objective
Provide a standard methodology that appropriately balances accuracy and simplicity for
calculating flows and storage parameters used in the design of drainage facilities in the
District.
L8]08-00Pad uuis\uction2
2-9
Current Program
The Rules and Regulations provide specific, detailed technical guidance on a number of
stormwater issues related to hydrology, hydraulics and detention basin sizing. The following
overview of MSD's current program focuses on the flow and storage methodology for sizing
storm sewers and detention basins.
FIow Methodology
• Stormwater flows are calculated by the Rational Method with PI values (runoff
coefficient times rainfall intensity) provided in the handbook based on
imperviousness. The PI factor is multiplied times the project area to determine the
peak flow.
• PI reduction factors adjusted for timing and for area are provided for trunk sewers
and main channels only.
• A 15-year frequency design storm is required in separate storm sewer areas, and a 20-
year frequency design storm is used in combined sewer areas.
• A twenty minute time of concentration which determines rainfall intensity is required
for all local drainage facility designs.
• Guidelines are provided for minimum impervious percentages by land use.
Storage Methodology
• Detention is required for projects which have a runoff peak flow differential of 2 cubic
feet per second (cfs) or greater between pre- and post -development. Detention is also
required when special conditions or problems exist downstream.
• Release rates are to be evaluated for the 2-, 5-, 10-, and 15/20-year frequency, 20-
minute duration storms to control existing peak flows from developments.
fs I08-00 Rst.touisLscctian2
2-10
" T h e d e t e n t i o n c a l c u l a t i o n i s b y u s e o f t h e c o n t i n u i t y e q u a t i o n w i t h a p p r o p r i a t e d a t a
p r o v i d e d . A r e c t a n g u l a r h y d r o g r a p h w i t h c o n s t a n t p e a k f l o w f o r a 2 0 - m i n u t e s t o r m
d u r a t i o n i s u t i l i z e d a s t h e i n f l o w h y d r o g r a p h a n d i s r o u t e d w i t h t h e f o l l o w i n g
e q u a t i o n :
w h e r e :
1 1 5
I - 0 = A T
I = I n f l o w
0 = O v e r f l o w
S = S t o r a g e
T = T i m e
" T y p e s o f a c c e p t a b l e d e t e n t i o n i n c l u d e b o t h d r y a n d w e t d e t e n t i o n , u n d e r g r o u n d
f a c i l i t i e s , a n d p a r k i n g l o t s .
" O t h e r d e s i g n c r i t e r i a g o v e r n m a x i m u m d e p t h ( 4 f e e t ) , m a x i m u m w a t e r l e v e l
f l u c t u a t i o n ( 3 f e e t ) , m a x i m u m s i d e s l o p e s ( 3 H : 1 V ) , m a t e r i a l s , l o w f l o w s w a l e s
( c o n c r e t e ) , s o d d i n g / m o w i n g , u s e o f p a r k i n g l o t s f o r s t o r a g e ( 8 t o 1 2 i n c h e s d e e p ) ,
e m e r g e n c y o v e r f l o w p r o v i s i o n s , m i n i m u m f r e e b o a r d a b o v e p e a k s t a g e ( 2 f e e t
m i n i m u m ) , e a s e m e n t s , m a i n t e n a n c e , f e n c i n g , a n d l o c a t i o n w i t h r e s p e c t t o t h e
f l o o d p l a i n ( t h e m a x i m u m d e p t h r e q u i r e m e n t i s n o l o n g e r e n f o r c e d ) .
" F o r d e v e l o p m e n t s i t e s w i t h d i f f i c u l t g r a d i n g c o n s t r a i n t s , t h e p r o j e c t m a y b e a l l o w e d t o
p r o v i d e a t t e n u a t i o n o f p e a k f l o w s f o r a r e a s u p s l o p e o f t h e p r o p o s e d d e v e l o p m e n t s .
I n s o m e d e v e l o p m e n t s , a r e a s a r e p e r m i t t e d t o b y p a s s d e t e n t i o n i f g r a d i n g c o n s t r a i n t s
a r e t o o s e v e r e .
I s s u e s / N e e d s
T h e c u r r e n t M S D r e g u l a t i o n s g e n e r a l l y p r o v i d e s o u n d t e c h n i c a l g u i d a n c e i n a n u m b e r o f
a r e a s . H o w e v e r , s e v e r a l I i m i t a t i o n s h a v e b e e n i d e n t i f i e d w i t h t h e P I f a c t o r a p p r o a c h t h a t
m a y b e u n d e r e s t i m a t i n g f l o w s a n d m a y b e p r o v i d i n g i n a d e q u a t e s t o r a g e a s s o c i a t e d w i t h
d e t e n t i o n b a s i n s i z i n g .
1 : 8 1 0 8 - 0 0 1 L s t . l o u i s \ s c a ' t i o n 2
2 - 1 1
Flow Methodology
The Rational Method is a standard, appropriate methodology for sizing pipes and inlets.
MSD guidance on PI factors covers typical land uses, but does not account for changes in
slope that can significantly affect the runoff coefficient. Adjustments for slope can be found
in the literature, but must be incorporated into the Rules and Regulations.
The Rules and Regulations require a standard 20-minute rainfall duration for sizing inlets,
storm sewers and detention basins. In the case of storm sewers, PI reduction factors are
provided to adjust for longer times of concentration on larger areas associated with larger
storm sewers. However, for times of concentration less than 20 minutes, no adjustment
factors are provided. In these cases, the current methodology may be underestimating flows
and undersizing smaller pipes and inlets, causing overland flows more frequently than
would be expected. There is also concern that the specific inlets are not appropriate for the
design flows and slopes in the St. Louis area.
Current practices require a 15/20-year design basis for sizing inlets and storm sewers. This
design basis is consistent with the Ievel of protection policy for the "design" component, but
does not require an overflow component to accommodate up to the 100-year event.
These issues require adjustments or modifications to the Rules and Regulations regarding the
flow methodology. Existing methodologies and procedures to date has not resulted in
catastrophic failure of the stormwater system components although it is suspected that some
upstream components of the drainage system may not function as designed. Modifications
to the rules will result in more effective drainage system designs and will achieve the desired
level of protection.
Storage Methodology
The storage methodology is a simplification of a Rational Method based approach to develop
a simple way to size detention facilities. The current 15-year design is inconsistent with the
new 100-year design recommended in this report and will require an appropriate
modification to the Rules and Regulations. The current methodology utilizes a 20-minute
duration, constant flow, inflow hydrograph. This approach is an over simplification that can
1:810 8.001 \ut.l o u i 51se c ti o n2
2-12
significantly oversize or undersize a detention facility, depending on the size and timing of
the upstream drainage area. A more appropriate approach would utilize an inflow
hydrograph which reasonably represents the peak flow and volume that would enter the
detention basin. The hydrograph would be developed based on the actual flow and timing
characteristics upstream of the detention basin. This modification would ensure proper
sizing of detention basins. In general, a 24-hr storm duration has been found to be
appropriate for sizing detention storage.
Some developers have expressed confusion about the application of various land
uses/impervious categories for developing flows and storage volumes. Multiple impervious
categories can be used to adequately represent the runoff potential of the development. MSD
may need to further explain its practices or educate the engineering/development
community regarding its Rules and Regulation to resolve this issue.
Release rates are determined based on pre -development peak flows Ieaving the developement
and are only provided for up to the 15/20-year events. The section on release rate (Section
2.2.3) examines the current release rate policy and concludes that it does not provide flow
control downstream. A more restrictive release rate that accounts for potential impacts
downstream is required.
The current MSD practice of allowing detention of upstream areas (rather than bypasses) or
exempting detention in difficult grading situations does not provide effective control of flow
increases from development. MSD should consider modifications to its position in these
instances. If offsite flows are routed through a detention basin, then the outlet is generally
sized much larger and the onsite flows are released at an increased rate which could
subsequently increase the downstream flows. Thus, it is recommended that offsite flows be
required to bypass detention basins or that developers prove that their outlet will provide
adequate detention for the onsite runoff.
The current storage methodology has provided technical guidance for detention basin sizing
which has resulted in construction of numerous detention facilities across the District. The
limitations in this methodology limit the effectiveness in controlling flow increases from
1:9108-001 Lst.lou is\senion2
2-13
development. Modifications to the Rules and Regulations are required to be consistent with
new level of protection criteria and to provide design flows and storage that meet the
objectives of the SSMIP.
Conclusions and Recommendations
The following interim recommendations are made as a starting point for current development
reviews. As the watershed pilot studies are completed, the release rate approach will be
finalized and more information will be developed to document the effectiveness of projects to
solve existing problems. Upon completion of the pilot watershed plans, these
recommendations should be finalized and incorporated into the revised Rules and
Regulations.
Flow Methodology
1. The PI factors should be adjusted to account for slope.
2. The PI factors should be adjusted to reflect the actual time of concentration to the flow
point in question. MSD may want to consider a minimum time of concentration of 10 or
15 minutes as a practical consideration. This should specifically address inlet sizing and
specification of appropriate inlets. Also, MSD should consider allowing larger times of
concentration for pipes on larger developments that clearly warrant higher values.
3. Technical guidance should emphasize the overflow/design approach presented in the
level of protection section and the design basis for these components should be 100-
years/15-years, respectively.
Storage Methodology
1. Detention basins should be sized using the release rate approach to be finalized in the
pilot watershed plans. Storage calculations should be based on inflow hydrographs. A
TR-55 or similar method is suggested to facilitate MSD staff review. The hydrograph
should be developed using a 24-hour rainfall event. Storage routing should utilize "level
L6108•001,I.mui ection2
2-14
pool routing" which is also known as the "storage indication method". "Pond-Pac" or a
similar software package is suggested to facilitate MSD reviews.
2. Storage calculations should accommodate the 100-year design event, consistent with level
of protection policy.
3. Upstream, off -site areas should not be allowed to route flows through detention facilities.
Rather, drainage plans should include provisions to bypass these flows for the 15-year
and 100-year events.
4. Areas of development with difficult grading challenges that can not easily provide
detention, should not be permitted. Developers must provide the required detention in a
separate facility, or provide the necessary grading to route runoff to the main detention
facility.
5. MSD should update its Rules and Regulations and conduct a series of workshops with
developers and the engineering community. These workshops will serve to educate these
technical audiences on the old and new provisions of the Rules.
2.2.3 RELEASE RATE AND DETENTION BASIN SIZING
As watersheds are developed, more and more area is covered with impervious surfaces
producing higher peak flows and larger volumes of runoff. These higher peak flows and
greater volumes more often than not result in increased flooding and erosion problems. To
mitigate these effects, detention basins are often employed to hold back stormwater runoff
generated during a storm and then release it over a longer period of time. The "release rate"
is the allowable rate for discharging water from the detention basin. With the appropriate
release rate and the proper sizing methodology, the detention basin can prevent increased
flooding problems downstream. Downstream system capacity, the response time of the
watershed, and the individual watershed characteristics are critical factors that must be
considered when selecting the release rate.
1:6I0B-OO Rst.louis\section2
2-15
Different methods are used nationwide for determining the allowable release rate. The most
common, similar to MSD's existing requirements, is to limit post -development peak flows to
pre -development peak flow. Although this method may control flows at the outlet from the
development, it often is not fully effective in controlling peak flow increases downstream of
the development. This section evaluates potential methods to select an appropriate release
rate and size detention facilities so that downstream impacts are also controlled.
Objective
Limit local, post -development peak flows so that downstream peak flows and stages are not
increased above pre -development conditions.
Current Program
MSD's current release rate criteria limits local post -development flows to pre -development
conditions for various design storms from the 2- through 15-year return period and has been
in effect since December 1993. All developments which will potentially increase flows by
more than 2 cfs are required to incorporate detention. The current criteria requires that the
detention basins limit peak flows to pre -development conditions; that is, during a 15-year
event, the peak flow leaving the development must be no greater than the pre -development
15-year flow. Regulations do not require evaluating watershed -wide impacts or considering
storms Iarger than the 15-year return period storm.
Problem/Issue
The current program effectively controls flow increases for the design event at the
development outlet, but does not ensure that downstream flows are not increased because it
does not account for the timing and cumulative impacts of peak flows. The current criteria
only controls the peak flow at the development outlet. It does not control the increase in
runoff volume which tends to increase the overall flow from the development. These
increased volumes result in increases in flow during non -peak times which are not controlled
by the current criteria. The result is that increases in off-peak flow cumulatively produce
1: 8108-0011sc.l ou islsecu on 2
2-16
higher peak flows at points downstream in the watersheds. To effectively control these
downstream flow increases, the release rate must be more restrictive to also control increases
in flow from the development during off-peak times.
As discussed in the level of protection section, potential adoption of a 100-year level of
protection requires MSD to establish appropriate design criteria to achieve that level of
protection when sizing and designing detention basins. Current criteria only require sizing
detention basins up to a 15-year event (20-year in St. Louis). For these design conditions, a
100-year event will fillup a detention basin and overflow downstream, providing little, if any,
control of the 100-year flow. Therefore, detention basin sizing criteria must define how much
water can be released by the basin (the release rate) and how much water must be stored in
the basin (the storage volume) for a 100-year event.
Potential Options/Solutions
In discussing the development of detention basin criteria, the SSC proposed that the objective
of detention should be "to limit flows from new development to be no greater than existing
peak flow conditions at all points in the watershed". The primary significance of adopting
this objective is that it disqualifies the existing District detention basin sizing approach
because its basis of control is "local" as opposed to "downstream" flow conditions. In other
words, current MSD criteria have been established to control flows at the outlet from
development and do not consider any potential effects offsite at downstream points in the
watershed.
Four approaches were considered for determining detention basin release rates and storage
volumes and were evaluated and compared to the current District requirements determine
the most appropriate approach to meet the detention objective of the MSD (seven approaches
were originally considered, but four were considered in detail). Figure 2-1 provides a
graphical description of these methods.
Is 1 os-Oo 1Vtiouia-ksaGonz
2-17
Ks\8108\
F!02—I
10/03/95 16z41$38
0:00'31
M. KUZEL. NMW—CHI
0
J
U-
3
0
—J
I
POST -DEVELOPMENT HYDROGRAPH
POST -DEVELOPMENT
HYDROGRAPH WITH
DETENTION FOR
PEAK RATE CONTROL
TIME PRE -DEVELOPMENT HYDROGRAPH
APPROACH No. 1
LOCAL FLOW CONTROL
POST -DEVELOPMENT HYDROGRAPH
TIME
100 YEAR DOWNSTREAM
PRE -DEVELOPMENT
PEAK RELEASE RATE
APPROACH No. 5
DOWNSTREAM EXISTING 100-YEAR FLOW CONTROL
cfs/acre )
0
J
u+
0
J
W
CRITICAL RUNOFF
PERIOD
POST -DEVELOPMENT
HYDROGRAPH WITH
VOLUME CONTROL DURING
THE CRITICAL RUNOFF PERIOD
TIME
APPROACH No. 3
VOLUME CONTROL
POST -DEVELOPMENT HYDROGRAPH
TIME
. . rBANKFULL DOWNSTREAM
PRE -DEVELOPMENT PEAK
RELEASE RATE
APPROACH No. 7
DOWNSTREAM EXISTING BANKFULL FLOW CONTROL
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
ALTERNATE METHODS FOR RELEASE RATE AND DETENTION BASIN SIZING
environmental services
Figure No. 2-1
Approach No. 1 - Local Flow Control Approach. Limit local, post -development peak flows to
local, pre -development peak flows for the 100-year event.
This approach is similar to the current MSD approach except that the design criteria has been
changed from the 15-year event to the 100-year event. For this approach, a peak flow for
100-year pre -development conditions is determined for a development and established as the
release rate. A runoff hydrograph is generated from the site for the post -development
condition. The difference between the post -development hydrograph and the pre -
development peak flow is the required storage volume.
Approach No. 3 - Downstream Critical Runoff Period Analysis : Limit local, post -
development runoff volumes during the critical runoff period to local, existing condition
runoff volumes during the critical runoff period for the 100-year event.
This approach uses a volume -based methodology (volume control) to limit flow increases at
downstream points in the watershed. In this approach, runoff volumes are limited to pre -
development volumes during a "critical runoff period". The critical runoff period is
determined through watershed computer models which can be used to verify that
downstream flow increases will be controlled to an acceptable level. This approach has been
successfully applied in a number of stormwater programs across the country including
Jacksonville, Florida.
A watershed computer model is used to determine runoff hydrographs for existing
conditions at downstream points in the watershed and the outlet for the development. The
watershed runoff hydrograph is evaluated and a critical runoff period is defined which
represents the critical time period before and after the peak flow when flows from various
points in the watershed are contributing to the watershed peak flow. This critical runoff
period is applied to the local runoff hydrograph to identify the time period when volume
increases must be limited. The release rate from the proposed detention basin is adjusted
until the volume of runoff released from the development during the critical runoff period is
equal to the volume released for existing conditions during the same time period. Limiting
I:8I08-00I Ltt.lo u is\scction2
2-19
the volume during the critical runoff period limits any flow increases downstream. This
method does take into account the actual site conditions of land use, soils and slope.
Approach NQ. 5 - Downstream Existing Flow Approah: Limit Iocal, post -development peak
flows to the downstream existing condition 100-year peak flow using a cfs/acre approach (cfs
= cubic feet per second).
The downstream existing flow approach or cfs/acre approach is based on identifying a
critical point downstream where flows must be controlled and determining the existing
condition peak 100-year flow. This flow is prorated across the watershed based by area and
assumes that the resulting "unit release rate" will limit flow increases at downstream points
in the watershed. The additive effects of these unit release rates will never be more than the
original pre -development peak flow downstream in the watershed.
A watershed computer model is used to estimate existing condition 100-year flows at the
downstream end of the watershed. The existing condition 100-year peak flow is divided by
the total watershed area to develop a unit release rate for the watershed. The unit release
rate is multiplied by the area of the proposed development to determine the local release rate
for sizing the detention basin. A post -development runoff hydrograph is prepared for the
development. The difference between the post -development hydrograph and the release rate
is the required storage volume. This method does not consider individual site conditions
such as soils, slope and land -use and is instead based on characteristics of the whole
watershed being applied to each development within the watershed.
I:8 E08-0611sdouislsecuon2
2-20
Approach No. 7 - Downstream Bankfull Approach: Limit local, post -development peak flows
to downstream bankfull conditions (approximately a 2-year event).
The bankfull approach is the same as Approach No. 5 except that the existing condition
bankfull flow at the downstream end of the watershed is used to determine the release rate
instead of the downstream existing condition 100-year flow. The downstream bankfull flow
is prorated across the watershed by area to determine the release rate. This approach is a
more restrictive version of Approach No. 5 in that downstream flows would never exceed
bank full conditions (approximately a 2-year event). This approach attempts to control both
flooding and erosion impacts of new development, by reducing flows from the
predevelopment conditions.
Existing MSD Requirement Approach: Limit local, post -development peak flows to local,
pre -development peak flows for the 2-, 5-, 10-, and 15-year events.
Pre -development and post -development runoff hydrographs are determined at the outlet of
the development based on MSD's current approach. The difference between the pre- and
post -development hydrographs is the required storage volume.
A preliminary hydrologic analysis was conducted to compare the approaches in terms of the
required volume of storage. Table 2-2 presents preliminary estimates of storage for each of
the above approaches based on the physical characteristics of some recent developments and
some coarse assumptions about watershed modelling results. Storage volumes were based
on approximate procedures that will be verified during the pilot watershed planning tasks.
The various release rate approaches produced large variations in the required storage
volumes.
I:a Ios-ao lltt.!oulsksecuonz
2-21
Table 2-2
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Preliminary Estimates of Detention Storage Volumes for Various
Release Rate Approaches
(Volumes in Acre -Feet)
Development Site
and Area
Site A
11.48 ac
Site B
3.0 ac
Site C
50.7 ac
Site D
3.3 ac
Site E
33.6 ac
MSD
Approach
.37
0.09
1.84
0.1I
2.55
r
Method #1
Peak Control
.46
0.08
0.72
0.05
2.89
Method #3
Volumetric
Control
1.41
0.34
4.09
.35
10.29
Method #5
cfslac
1.62
.46
5.87
.50
7.64
Method #7
cfs/ac
Limited to
Bankfull
2.46
.66
10.28
.72
11.68
I:8108-00lt Uouis4able2-2
2-22
Approach No. 1, Local 100-year Peak Flow Control, generally produces storage volumes that
are similar to those required by the current MSD approach (Approach No. 1, however, does
not control downstream flows). Approach No. 3, Volume Control, requires storage volumes
two to four times greater than the current MSD approach. Approach No. 5, Downstream
Control-cfs/acre, requires storage volumes three to five times greater than current
regulations. Approach No. 7, Downstream Bankfull Control-cfs/acre, requires storage
volumes six to seven times greater than what is currently required. Although these flow
control approaches may be modified in the pilot watershed modeling, they serve as
indicators of the impacts that these changes could have on storage requirements for
development. Approaches 3, 5 and 7 all require significant increases in storage volume to
control downstream flow increases.
In addition to the storage impacts, a number of other issues should be considered relative to
selecting an appropriate release rate and detention basin sizing criteria. Table 2-3 provides a
comparison of the approaches in terms of effectiveness, administrative complexity, fairness
and equity, and required storage volume.
Approach No. 1 and the current MSD approach do not achieve the desired objective for flood
control, as downstream flows will still increase with development. Approaches Nos. 3, 5 and
7 achieve the flood control objective.
I:8108 -00 lla.l o u is\uctio n 2
2-23
Approach
#I Local Flow Control
Approach: Limit local,
post -development peak
flows to local, existing peak
flows for 100-yr event
Existing District
Approach: Limit local,
post -development peak
flows to local, existing peak
flows for 2-, 5-, I O- and 15-
yr events
#3 Downstream Critical
Runoff Period Approach:
Limit local, post -
development runoff
volumes during critical
runoff period to local,
existing conditions runoff
volumes during critical
runoff period for the 100-yr
event
#5 Downstream Existing
Flow Approach: Limit
local, post -development
peak flows to the
downstream existing
conditions peak flows using
a cfslacre approach
#7 Downstream Bankroll
Flow Approach: Limit
local, post -development
peak flows to downstream
hankfull(approx. 2-yr)
condition
Effectiveness
Table 2-3
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Qualitative Comparison of Detention Approaches
Potential Consequences of Approach
Administrative Complexity
Flood Control
Water Quality
Erosion Control (a)
Technical Reqmts.
Permit Review
Local flooding will be
prevented but new downstream
flooding will occur and be
frequent (yearly).
Local flooding will be
prevented up to the 15-yr event
but new downstream flooding
will occur during major events
and possibly during more
frequent events (yearly). Does
not provide 100-yr level of
protection.
Should control
local/downstream flow
increases better than above
approaches. Actual watershed
timing or rain distribution
could result in increased flows.
Could offer exemption from
detention for areas not affected
by critical runoff period.
Prevents increase in both local
and downstream flooding.
May actually reduce flows
below existing conditions and
assist in solution to current
flooding problems.
Prevents increase in local and
downstream flooding and
actually reduces downstream
flows and stages. May solve
many existing problems in
developing watersheds.
Will not prevent
increased erosion either
locally or downstream.
Same as Approach #1,
Also, may limit local
erosion for frequent
events.
Will not prevent
increased erosion from
development. Could
increase local erosion
in areas exempted from
detention.
Will not prevent
increased erosion from
development, but rate
may be slightly slowed
in comparison to above
approaches.
May provide local
erosion control
benefits, but may
increase downstream
erosion potential.
No improvements to
stormwater quality.
No improvements to
stormwater quality.
No improvements to
stormwater quality.
No improvements to
stormwater quality.
Marginal improvements
to stormwater quality.
Easiest Approach. Simple calculations
can be used. No considerations need to
be given to downstream effects.
Requires slightly more effort than for
Approach 01. Multiple calculations are
necessary for several design storms.
Most complex approach. Temporal
considerations must be considered
downstream requiring more complex
analysis. Requires iterative
computations to determine
volume/releaserates, Volumetric
approach is difficult to understand.
Could he as simple as #1 and existing
District approach because predetermined
maximum allowable unit runoff rates
eliminate the need for downstream
analysis. Provides single release rate
value for each watershed or, if desired.
for the entire District.
Could be as simple as #1 and existing
District approach because predetemsined
maximum allowable unit runoff rates
eliminate the need for downstream
analysis. Provides single release rate
value for each watershed or, if desired,
for the entire District.
Similar to existing
District Approach.
Permit reviewer can
easily review permit
applications and
explain requirements to
developers.
Existing, familiar
approach. Permit
reviewer can easily
review permit
applications and
explain requirements to
developers.
Permit reviewer must
review more
technically -demanding
application and
calculations. Could
result in lengthier
application preparation
and more review time
demands by District
staff.
Permit reviews are
similar to Existing
District Approach.
Permit reviews are
similar to Existing
District Approach.
Equity/Fairness
Provision For
Volume
Comments
Same standard for all development.
Same standard for all development,
Same standard for all development.
Addresses both local effects of
development and downstream
effects but he perceived as
inequitable if downstream
development is exempt from
detention.
Allocates existing flow across entire
watershed resulting in volume
requirements independent of
existing local tunoff conditions.
May be inequitable for
developments with very low
predevelopment runoff conditions.
Allocates existing flow across entire
watershed resulting in volume
requirements independent of
existing local runoff conditions.
May be inequitable for
developments with very law
predevelopment runoff conditions.
Least storage
volume required.
Possibly more
storage volume
required than for
Approach # I .
More storage
volume needed than
for Approach #1 and
existing District
approach.
More storage runoff
volume than for
above approaches.
Requires large
volume of storage.
Mare storage
volume than any of
the above
approaches.
Does not accomplish
objective of limiting
increases in
downstream peak
discharges for any
storm event.
Does not accomplish
objective of limiting
increases in
downstream
discharges for any
storm event.
May be able to
achieve flood control
objective, but
requires involved
computation
procedure and
negotiations related
to timing of runoff.
Achieves flood
control objective and
is technically and
administratively
simple, but requires
more storage volumes
than above
approaches.
Achieves and exceeds
objective of
controlling i00-yr
flooding increases.
but requires
impractical storage
volumes.
(a) In order for any of these alternatives to be effective in improving stormwater quality, wet -bottomed ponds must be designed for extended detention.
None of the approaches clearly showed significant erosion control benefits. It appears that
Approach No. 7 could actually increase erosion because it may increase the frequency and
duration of bankfull conditions and the associated erosion. This would need to be evaluated
through actual watershed modeling.
Approach No. 1 and the current MSD approach are the simplest from a technical perspective.
Approach No. 3 is most complex, requiring detailed watershed modeling to define the critical
runoff period and an iterative process to determine the required storage volume. Approach 3
can be somewhat simplified for review purposes with standard detention design parameters
tested during the watershed modelling. Approaches Nos. 5 and 7 require watershed
modeling to determine unit release rates, but actual storage calculations are straight forward
once the release rate has been determined.
MSD's ease of reviews when permitting new development is directly related to the technical
requirements above. Approach No. 3 by far would be the most difficult to review, while
Approach No. 1 would be the simplest to deal with in a permit review situation.
Approaches No. 5 and 7 introduce some fairness and equity concerns because release rates
for any particular development are based primarily on downstream conditions rather than
the actual area being developed. Approaches No. 1, 3 and the current MSD approach are
based primarily on specific on -site conditions, and thus reduce. the potential for fairness
concerns.
The most important factor in the comparison of the approaches is the required storage
volume because it has a direct impact on the cost of development and the effectiveness of
detention. Approach No. 1 and the existing MSD approach do not achieve the desired
detention objective of controlling flow increases downstream in the watershed. Approach
No. 7 accomplishes this objective, but it may be overly conservative in that it requires
significantly larger storage volumes. Approaches No. 3 and No. 5 achieve the desired
objective but also require large increases in storage.
1:8IGa-OO Ilst.louis sectian2
2-25
Approach No. 1 and the current MSD approach must be eliminated from consideration
because they do not meet the required objective of controlling downstream flow increases.
Approach No. 7 achieves the objective, but requires the largest storage volume without
definitive erosion control benefits. Only Approaches No. 3 and 5 appear to be worthy of
further consideration by MSD.
Recommendation
(1) The SSC recommended that Approaches No. 3 and No. 5 be applied and tested in the
pilot watershed plans. Both appear to be able to achieve the desired detention
objective. Both must be evaluated under actual conditions rather than hypothetical
watershed situations. Following analysis of the pilot watersheds, the MSD will be able
to make a final recommendation on the detention basin sizing criteria approach to
determine release rate and required storage volume.
2.2.4 FLOODPLAIN REQUIREMENTS
Floodplains are a natural and important part of the drainage system. These low-lying areas
adjacent to streams can provide storage and/or conveyance for floodwaters from large
storms that overtop the banks of the stream. These floodplain areas are also subject to
development activity, and structures in the floodplain are more susceptible to flooding and
erosion damage because of their proximity to a stream or river. Development in the
floodplain generally involves some filling of the floodplain that reduces the storage and
conveyance capacity of the watershed and may lead to increased flooding and erosion
problems. Thus, development in floodplain areas should be regulated to minimize
stormwater damages throughout the watershed.
Objective
Restrict development in floodplain areas to minimize flooding and erosion potential-
i:8108- 001 Ln.l o u iAsec t io n 2
2-26
Current Situation
Floodplain requirements have been primarily managed by the local municipalities and St.
Louis County because it is an issue closely related to zoning and land use restrictions. These
local governments have ordinances that fulfill the minimum requirements of the National
Flood Insurance Program administered by the Federal Emergency Management Agency
(FEMA) and some include slightly more restrictive requirements. The current MSD policy of
reviewing floodplain studies is sufficient in structure to verify that FEMA minimum
requirements for development activity in the floodplain are met.
MSD requires a floodplain study for any development that is to be in the 100-year floodplain
as shown on the FEMA Flood Boundary and Floodway maps. In addition, a floodplain
study is required if any watercourse cannot be contained in a 66 inch pipe for the 100-year
event. For developments in a FEMA identified floodplain, MSD does not specify the
allowable rise in water surface elevation (WSE) from the pre -development condition.
However, FEMA requirements only allow up to one foot of rise in WSE due to floodplain
development. MSD Rules and Regulations require that bridges in the floodplain shall have a
minimum of 1-ft of freeboard over the 100-year WSE and roadways with culvert crossings in
the 100-year floodplain must have a minimum of 2-ft. of freeboard over the 100-year WSE.
Basement or first floor elevations are required to be at least 1-ft. above and low sill is
required to be at least 2-ft. above the 100-year WSE. Floodplain filling is subject to state or
local government restrictions, and thus MSD has no requirements for compensatory storage
when development takes place in the flood fringe (compensatory storage is a requirement to
replace storage nearby in the floodplain when fill activities reduce the available floodplain
storage). The cumulative loss of floodplain storage in a watershed is likely to result in some
measure of additional flooding. A review of local municipality ordinances did not identify
any communities with compensatory storage requirements, other than St. Louis County
which does have such requirements.
I:8 [ 08.001,a.louislseaionl
2-27
Problems /Issues
The cumulative or watershed -wide effects of floodplain filling are not well defined in the
MSD service area, and are not considered in the current MSD regulations. MSD is primarily
concerned with floodplain storage and conveyance impacts on the adequacy of the drainage
system. In steep slope areas, the effects are often minimal, but there are areas along the
channels at the lower end of MSD watersheds where effects could be significant and flood
damage may result. In some of these areas it may be appropriate to regulate fill activities
and require compensatory storage.
Potential Options /Solutions
The watershed master plans will evaluate where floodplain storage is a critical factor in not
increasing flood stages. MSD is authorized in the Plan to regulate the floodplain but has
thus far taken a limited role as the local municipalities or the County have taken the lead in
this area. The available options relative to controlling floodplain development are:
• MSD regulation of floodplain development
• Continued municipality regulation of floodplain development with MSD passing
information about critical floodplain areas to the municipalities for regulation or
enforcement
Because FEMA floodplain requirements must be met by local municipalities to be a part of
the National Flood Insurance Program, MSD floodplain regulation would at least partially
involve duplicated effort. Also, because floodplain regulation is closely related to zoning, it
is more appropriate to have municipality -based authority and requirements. The downside
of local floodplain regulation is that standards may not necessarily be uniform or uniformly
applied and regional effects may not be given adequate consideration. To help resolve these
problems, a model stormwater ordinance for municipalities which addresses floodplain
requirements such as compensatory storage should be considered by MSD.
11106-OO nst.louislsuaion2
2-28
Recommendations
(1) Continue to defer primary floodplain regulation to the municipal level.
(2) Pass on modelling information about the effects floodplain filling and suggested
requirements (compensatory storage) to local municipalities.
(3) Consider incorporating floodplain requirements into a model ordinance for adoption
by local municipalities.
2.2.5 DEVELOPMENT S1Th EROSION AND SEDIMENT (E&S) CONTROL
Controlling erosion and sediment (E&S) transport from development sites can have a
dramatic effect on maintenance needs due to sedimentation and can help to protect water
quality. The conditions during construction provide ample opportunity for migration of
large amounts of eroded soil unless adequate steps are taken to limit the process. When
deposited, sediment can reduce the capacity of inlets, sewers, channels and detention
facilities thereby increasing the need for maintenance and decreasing the effectiveness of the
drainage system. Increased sedimentation can also reduce the value of reservoirs and
streams for wildlife and recreation and causes complaints from downstream residents.
Objective
Working within MSD's authority, minimize the detrimental erosion effects associated with
development especially with respect to capacity and maintenance of drainage facilities.
Current Situation
The Missouri Department of Natural Resources (DNR) "Stormwater Permit Requirements for
Land Disturbances Activities", Missouri Regulation 10 CSR 20-6.200, states that a Missouri
State Operating Permit for stormwater discharges is required for land disturbances (i.e.
grading, excavating, etc.) of five (5) acres or more. The majority of the construction sites
1:8108-00 Llst.louis\scction2
2-29
within MSD's service area will fall under this category. In addition to specific practices to be
implemented at the construction site, sampling of discharges is required under this permit to
demonstrate performance of E&S control measures. Unfortunately, enforcement by DNR is
very limited.
MSD does not currently regulate erosion and sediment control. It is considered a grading
issue which has historically been under the jurisdiction of local governments. Of
approximately 70 local governments that responded to a questionnaire on stormwater issues,
only 11 identified that they have specific E&S control requirements. Despite this low number
of affirmative responses, it is expected that many more have E&S requirements either
directly or indirectly because the County has specific E&S requirements and performs
grading inspections for many municipalities (St. Louis County, 1995). But, even for those
municipalities where the initial placement of E&S controls is furnished and inspected, there is
little or no follow-up inspection to ensure proper maintenance of these devices.
problems /Issues
The lack of adequate E&S control is one major shortcoming of the overall stormwater
management efforts in the MSD service area. The following list summarizes the problems
and issues with the current situation.
• Construction sites are often cleared and graded with little or no erosion controls in
place. If erosion control measures are used, maintenance of these devices are
often inadequate.
• For the majority of the municipalities, the number of grading inspectors is either
non-existent or inadequate to properly monitor compliance with and/or
maintenance of erosion control measures.
• Currently, MSD has no requirements for E&S control measures to be installed and
maintained on a construction site for the duration of the project. The District's
erosion control requirements are essentially limited to open channels, outlets,
1:8108-001u.1ov iAsecuon2
2-30
culverts, and bridges, as discussed in Chapter 4 of the Rules and Regulations and
Engineering Design Requirements for Sanitary Sewage and Stormwater Drainage
Facilities (1993).
• DNR enforcement of operating permits is not adequate to ensure compliance.
Potential Options/Solutions
It would be beneficial if MSD had ultimate authority to regulate E&S control, but because the
municipalities control grading review and enforcement, MSD authority is limited on a
practical level. The Plan is not specific on MSD authority for E&S control, although impacts
on drainage system capacity, maintenance, and water quality may justify MSD involvement
at some level. The major options available to MSD to address the E&S control issues are:
• Continued local municipality responsibility for E&S control with MSD support to
provide to help wherever possible.
• MSD regulation of E&S including plan review and inspection.
MSD regulation of E&S control would be advantageous in that standards would be uniform
across the service area and responsibility would be centrally Iocated, thus filling a distinct
void in the E&S control efforts for the area. Disadvantages include the fact that MSD would
have to initiate a new aspect of stormwater management (including staff and resources) that
duplicates current municipality efforts and this policy may step beyond the existing authority
of MSD. Also, MSD would need to be involved much earlier in the development review
process (i.e., at the grading plan stage) when municipalities are already be involved. Because
of these factors, MSD regulation of E&S would require additional effort (and cost) versus
incorporating E&S control into local municipal grading review and inspection.
MSD can offer secondary support of E&S control that would help achieve the objective.
Consistent standards could be achieved by MSD preparing or referencing a document with
recommended E&S measures and incorporating E&S review and inspection into a model
1:8 108-001 \st.l ou isksection 2
2-3 I
stormwater ordinance. MSD could also monitor E&S control while MSD construction
inspectors are on site for drainage and sanitary facility inspection. This would require
minimal extra effort for MSD and violations could be reported to the municipalities or
County for enforcement. This would also help to ensure maintenance of E&S control which
is currently lacking. Finally, MSD could maintain a master list of municipal contacts for
E&S enforcement so that complaint calls can be efficiently directed to the proper authority.
Recommendations
The following recommendations are made to address the current issues and problems
associated with E&S control and work within MSD's defined authority and the current
regulatory framework:
(1) Continue local municipality responsibility for E&S control and provide support
where possible.
(2) Develop a model ordinance with site erosion control requirements and recommend
adoption by the municipalities. The ordinance should, at a minimum, require that:
• The developer submit an erosion control plan to the municipality for review and
approval as part of his/her construction plans package, and make this a
requirement prior to issuance of a grading permit.
• The developer install erosion control measures and maintain them for the duration
of construction. These measures should be implemented when clearing and
grading operations begin.
• The developer be responsible for any clean-up and/or repairs necessary as a result
of sedimentation from site erosion. This should pertain to public rights -of -way,
public easements, creeks, and channels as well as private property.
I:8108-6O 1ltt.louislsccti on2
2-32
(3)
• The developer pay a grading inspection fee to provide adequate funds for
increased inspection.
• The developer could be required to execute a bond which requires him/her to
guarantee compliance with the erosion control plan. St. Louis County currently
has this requirement place.
• Since state regulation 10 CSR 20-6.200 only requires a permit for land disturbances
of five (5) acres or greater, the municipalities could be requested to consider
decreasing this minimum size. For example, the County's regulations apply to
any size project.
Observe E&S control effectiveness when on site for MSD-related inspections and
report problems to local municipal or County authorities for enforcement.
(4) Encourage municipalities with limited manpower, to contract with the County or
others to perform grading inspections.
(5)
Develop a complaint routing system which would insure that E&S complaints called
in to the District can be efficiently directed to the County or municipality in which the
erosion problem is occurring.
2.2.6 WATER QUALITY
In general, urbanization of a watershed has an adverse impact on the quality of water that is
delivered to streams and lakes. Stormwater runoff from urban areas typically carries more
pollutants than runoff from natural areas unless control measures are in place. Recognizing
the impacts of stormwater on overall water quality, the National Pollutant Discharge
Elimination System (NPDES) stormwater rules were instituted by the federal government in
1990 to reduce these adverse impacts. This program is not currently applicable to the St.
Louis area because the City of St. Louis was exempted because of its combined sewers.
When the NPDES program is applied to the St. Louis area, the water quality issue may
1:8108-00l \.1.10 u iislsccti o n2
2-33
become important from a regulatory compliance standpoint. In addition to this potential
regulation, private citizens and environmental groups are interested in minimizing the
degradation of the areas natural resources.
Objective
Define the role of water quality in the MSD SSMQ' and if appropriate, incorporate into the
SSM1P planning process.
Current Program
At present, MSD does not have a legal definition of stormwater quality in their "Rules and
Regulations" although information concerning stormwater quality may be scattered
throughout several related ordinances. This means there is no generally available or
published legal authority specifically targeting stormwater quality or defining acceptable
discharges into the stormwater system.
Both state and federal stormwater quality programs are still evolving and are generally
understaffed and underfunded. The Clean Water Act reauthorization and stormwater
NPDES Permit Program will Iikely result in modifications designed to decrease the
requirements for municipalities, especially compared to the requirements for the first round
of the program developed in 1990.
The stormwater quality problem in the District is not well defined and its extent or
magnitude is not known. Experience in similar communities would indicate that a problem
exists. Erosion and sediment control from development is a known problem, primarily from
its impact on maintenance and system operation. Although erosion and sediment affects the
environment and the receiving waters, its water quality impacts are not currently an issue in
the area.
I:B i06-0014sc.louislucdon2
2-34
Stormwater runoff from developed and developing lands is typically transporting sediment,
nutrients, and other pollutants in greater quantities than occurs naturally. Once these
pollutants are put in motion by flowing water, the creeks and storm sewers will carry them
downstream where they have the potential to degrade rivers and lakes. Future federal and
state rule -making may require MSD to address stormwater quality.
Options available to MSD:
The following approaches are available to MSD for addressing stormwater quality issues.
• Maintain MSD's present limited involvement in stormwater quality, but improve
the effectiveness of erosion of sediment control practices for new development.
• Implement a comprehensive, proactive water quality component of the stormwater
program similar to the Federal NPDES stormwater program and require
appropriate water quality structural controls and BMPs on all development.
• Adopt some intermediate position that moves forward in the water quality area,
but does not impose mandatory requirements.
In the absence of state or federal mandates and associated funding, it is not appropriate to
commit to a comprehensive stormwater quality program at this time. A stormwater quality
program would place a significant additional burden on developers and MSD customers.
Furthermore, regulatory requirements are being re-evaluated and, could change significantly.
Nonetheless, some attention should be given to water quality measures that can be easily and
inexpensively implemented. Public Education is one such measure. MSD could document
all positive stormwater quality activities. Information provided to developers and engineers
could support designs that include water quality on a voluntary basis. Finally, MSD could
incorporate water quality benefits and retrofit potential into its projects when additional costs
are not significant.
I: 810 8-0011st . l o u isls e c t i o n 2
2-35
This approach would raise the water quality issue, provide information to the communications
program, and help to educate the public about the potential problems and need for potential
future water quality measures. Essentially, this activity would prepare the MSD for future
stormwater quality regulations when they are implemented by state or federal agencies.
Recommendations
(1) Assess the ambient water quality conditions for the area during the watershed plans to
determine the current quality impacts of stormwater:
(2) Document all positive stormwater quality actions and activities and raise the awareness
about stormwater quality through the public involvement and information program.
(3)
Provide developers, engineers and the public with sources of information on water
quality best management practices for voluntary implementation and revise any existing
standards that may preclude water quality design features.
(4) Prepare or recommend Erosion and Sediment Control Guidelines for use by developers.
(5)
Continue to monitor state and federal requirements that might affect MSD's stormwater
program.
(6) Identify potential water quality benefits and retrofit capability of capital improvements
that are proposed as a part of the watershed master plans.
2.2.7 CHANNEL TREATMENT
Open channel flow provides an attractive, natural method for conveying flows, but at the same
time, open channels are part of a dynamic process that represents a balance between the flows,
capacity and energy that can result in serious erosion and significant channel movement. The
resulting erosion and channel movement presents long term management and maintenance
challenges for MSD and local property owners. Various channel treatments or improvements
are available which can preserve the integrity of the channel and limit the effects of erosion.
I:8 I08-6O l lst.l ou islse cti on 2
2-36
Such treatments vary in cost, aesthetics, and ability to handle erosive conditions. This section
discusses the channel treatment issues, reviews MSD's current policy and makes
recommendation for modifications to improve the effectiveness and reduce the long term costs
associated with open channel conveyance features in the District.
Objective
Define acceptable channel bank (sidewall) and bottom materials and procedures that promote
proper drainage system function and define under what conditions MSD will maintain such
improvements.
Current Program
For existing channels, current MSD policy dictates that they be left in the natural state unless
there is an emergency situation with imminent threat to structures. In these cases, MSD has
used grouted riprap or vertical concrete walls to stabilize the threatening reach of the channel.
MSD does not currently have any published requirements for channel treatments that are to be
constructed or modified. Other channel treatments such as gabion walls can be installed by
developers, but MSD will not accept maintenance responsibility for such improvements.
problem/Is UP
Turbulent flow in open channels (natural channels) seeks to balance flow duration and velocity
with the natural armoring capability of the channel such as soil stability/erodibility and
vegetative cover. Natural channels constantly erode whenever flows reach erosive velocities.
Erosion results in down -cutting or meandering to ultimately reduce velocities. Erosion is
nature's way of modifying the channel to achieve equilibrium between flow and the channel.
The erosion problem is exacerbated by ongoing development and the associated increases in
flow. With these ongoing natural processes, use of natural open channels for stormwater
conveyance will ultimately require some form of erosion repairs or channel treatments. The
problem or issue is to determine what are appropriate acceptable channel treatments or erosion
controls, and when the District should accept them for maintenance.
1:8108-4f01 Lst-lou is'section2
2-37
Potential Option, /Ss1_u :onS
Present funding resources and priorities limit the channel treatment work done by MSD to
emergency actions. Present policy generally limits MSD capital improvements to
replacement/renewal functions on previous District improvements. With increased funding,
MSD should have the resources to more proactively address channel treatments. MSD needs to
address the questions of when some form of channel treatment is required and what the
channel treatment should consist of.
Channel treatments should first be considered in those areas where channel capacity is lacking
and increased conveyance is required to pass design flows. In the absence of a capacity
problem, channel treatments should be considered where erosion is severe or is threatening
structures. Spot applications of channel treatments as emergency repairs will often be
ineffective because the problem will just be moved downstream. The downstream conditions
must be considered and accounted for if channel treatments are to be effective.
In selecting an appropriate channel treatment for armoring or bank protection, the following
factors should be considered:
• Ability to stabilize the channel
• Ease of maintenance
• Effect on conveyance
• Long term maintenance cost
• Disturbance to surrounding area
• Initial construction cost
• Aesthetic and safety issues
• Impacts to downstream areas
Considering these factors, the following treatments or stabilization materials should be
evaluated:
• Cable concrete
• Loose rip -rap
• Crib walls
• Grouted rip -rap
1:8I08-13I3 Ilst.louis1section2
• Palmiter methods (wing dam, etc.)
• Concrete - Filled Fabric Envelope
• Gabion/revet mattresses
• Low Water Dam/Drop structure
(velocity control)
2-38
• Vegetation (bioengineering)
• Block/Stackable Wall(s)
• Flow training
• Concrete
Open channels versus enclosed channels
Open channel conveyance should be preserved unless cost or other practical considerations
suggest enclosing in a pipe would be more appropriate. The factors leading to the consideration
of enclosing a channel versus leaving the channel open include:
• Cost
• Design Capacity
• Velocity
• Safety
• Land use
• Maintenance requirements
• Right-of-way or easements
• Length of Channel Section
• Vicinity of other structures
• Vulnerability to Erosion
• Aesthetics
• Downstream Impacts
• Channel Storage
(hydrograph attenuation)
The enclosed channel should be designed to pass the 100-year flow, incorporating an emergency
overflow concept, and should not increase upstream water surface elevations above pre -project
conditions. Channel enclosures, other than typical storm sewer improvements, should be
addressed on a case, by case basis.
Preventative Measures
Because erosion and meandering are natural processes that are difficult to control in all
situations, erosion problems are sometimes better addressed in developing areas by
preventative, non-structural policy measures that keep structures away from the stream banks.
MSD is authorized in the Plan to set up building lines along streams that restrict development
adjacent to the streams. These building lines are often called "setbacks" because they determine
the minimum distance that a structure must be setback from the stream. Setbacks designed to
minimize erosional damages would include a distance that defines the area where the stream is
naturally expected to meander. This distance is dependent on the geomorphic characteristics of
the stream (such as slope, width, soil, flow, etc.) and will vary from one Iocation to another. To
this distance a safety factor is added to reduce the potential harmful effect of erosion on the
structure. Setbacks have been proposed and administered in a wide variety of locations
including northeastern Illinois, Orlando, Chesapeake Bay area, and Toronto, Setbacks can also
have other potential benefits including water quality enhancement and better maintenance
access.
Recommendations
1.8108.00 LLst.louisN.seceion2
2-39
1. Accept maintenance responsibilities (consistent with funding) for all approved and
accepted existing and future channel treatments.
2. Do not allow construction of any channel treatment that will not be maintained by MSD
unless a maintenance agreement with escrow is executed.
3. Develop a set of criteria that specifically defines the parameters that constitute an
acceptable channel treatment. This criteria should consider cost, life, maintenance,
expected velocities, downstream conditions, etc.
4. Encourage usage of appropriate natural channel treatment materials and techniques or
more earth -friendly erosion control techniques, including: bioengineering, erosion
resistant grasses, native deep rooted vegetative specifics, erosion control vegetative mats,
three-dimensional soil reinforcement mats, gabions, dumped rock, etc.
5. Consider alternate channel materials and procedures on a case by case basis considering,
cost, location, soils, slopes, existing vegetation, native species, construction or planting
season, conveyance and other site specific influences.
6. Develop a list unacceptable channel treatment materials. This list would be updated
periodically as: new materials and procedures are developed, previously disallowed
materials are improved and become acceptable, and previously approved materials prove
to create significant problems and are not allowed. Develop supporting documentation
and explanations about why or when particular treatments are unacceptable (temporary
only, limited life, not proven, causes problems downstream, restricts channel conveyance,
requires frequent or costly maintenance, etc.).
7. Consider a policy of requiring setbacks to keep future development away from streams
and help reduce the need for channel treatments.
1:8108-OO1ls1.1ouis\, tian2
2-40
2.3 )✓NGINEERING
In the Plan, MSD is charged to prepare or oversee preparation of plans and designs for any
additions or improvements to the drainage system. This also gives MSD responsibility for
design and construction of drainage facilities as needed. The Plan also explicitly states that
MSD is to review the plans for all drainage improvements and inspect the construction
activities for drainage system improvements.
These responsibilities are primarily executed by the MSD Engineering and Construction
Management Departments. The Engineering Department provides stormwater planning,
design of drainage system improvements, review of drainage facility plans, and mapping.
The Construction Management Department provides the services of field inspection and
construction oversight for drainage improvements. Stormwater planning identifies
improvements that are necessary to safely collect and convey stormwater to one of the three
major rivers surrounding metropolitan St. Louis (Meramec, Missouri, or Mississippi). Also,
the Engineering Department maintains a mapping database (on Intergraph Microstation) of
all known drainage and sanitary sewer facilities with the District's boundaries.
Two major areas associated with Engineering Plan Review and Inspection, and Mapping and
Database Information, were identified to be reviewed and are discussed in this section. MSD
planning and design of improvements to the drainage system are addressed in the Watershed
Planning Framework Report and specific recommendations will be contained in the
individual watershed plans produced in later phases of the SSMIP.
2.3.1 PLAN REVIEW AND INSPECTION
Plan review and inspection are important components of a stormwater management program
because they are the primary enforcement mechanisms to ensure that drainage improvements
are designed and constructed in accordance with MSD guidelines; that is, they are the means
by which standards and regulations, as discussed in the preceding sections, are put into
effect. Policy decisions must be made about what will be reviewed and inspected, when and
by whom.
1:8108-00Ilst.lout luction2
2-41
Objective
Review plans and inspect drainage facility construction to ensure compliance with MSD
standards and criteria.
Current Situation
MSD assumed the responsibility to approve, revise, or reject all stormwater and drainage
facilities proposed or proposed to be modified within the entire District through enactment of
Ordinance No. 7691. The review of plans by MSD took effect on April 1, 1989. The
document, The Metropolitan St. Louis Sewer District Rules and Regulations and Engineering
Design Requirements for Sanitary Sewage and Stormwater Drainage Facilities, outlines the review
process and the District's design standards. Figure 2-2 provides an overview of the plan
review and inspection in a development project. Whenever development activities occur
within the District, the plans for sewer and drainage facilities are reviewed by the
Engineering Department for conformance to the MSD's standards and criteria. When the
plans are submitted to the District, a review engineer is assigned who handles most of the
review. Some special items such as detention basin design and floodplain development are
reviewed by a separate engineer familiar with the MSD's requirements for those special
items.
Generally, the review is done in two stages. The first stage review typically takes about three
weeks and identifies any deficiencies in the plans. After the developer has remedied the
deficiencies, he submits the plans for a second review. MSD's goal for turn around of the
second review is about one week. Conversations with the Engineering Department indicate
that these goals are met well over 90% of the time.
Reviews are conducted to address both sanitary and stormwater requirements. MSD does
not review grading or earthwork and in some instances, local communities allow these
activities to take place prior to any reviews or approvals by MSD. At the time of plan
approval, a cash escrow must be deposited with MSD in the amount of 10% of the estimated
1:8 108-OO I kt.l ou islsectl o n2
2-42
Plan Review and Inspection Flowchart
MSD MSD
Fees Involvement
Pay Review Fee
and
Sanitary Conn.
Fee
Pay Const.
Permit Fee,
Escrows,
Recoupments
Inspection Fee,
and as -Built
Doc. Deposit
District Review/Apprv.
Calculate Escrows.
Easements Recorded
MSD Construction
permit applied for/granted.
District notified at least
24 hours before
construction.
PROJECT
BEGINS
I
Clearing of Site
I
Concept Plan
Local Municipalities
Involvement
'No permit generally required
for clearing. NPDES permit
for >5 acres of development.
Some projects need approval
to remove trees.
Preliminary Plat
Grading Plan (and
Erosion Control
Plan if required)
i
Local Preliminary
Plat Review/Apprv.
Local Preliminary
Plat Review/Apprv.
Grading of Site
Construction Plans
Record Plat
Local Grading Permit
Local Inspection
Local Construction
Plan Review.
Building permit issued
after MSD approval.
'City of St. Louis
doesn't require MSD
approval prior to issuing
building permit
(continued on next page)
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
PLAN REVIEW AND INSPECTION FLOWCHART
environmental services
2-43
Figure No. 2-2
MSD
Fees
As -Built
Doc.
is Deposit
Refunded
1/2 of Escrow
is
Released
Return Balance
of
Escrow
Monies
(continued from previous page)
Plan Review and Inspection Flowchart
MSD
Involvement
MSD punchlist
MSD Construction
Approval
Letter sent to Mun.
Sanitary Dist.
Commission
At 50% Subdivision
Completion, MSD
Dedication Inspection
If No Discrepencles,
Final Dedication and
MSD Acceptance
Construction of Sewers &
Drainage Facilites
Preliminary File
As -Built Plan for
Sewers/Drainage
I
Request Final
Const. Inspection
Punchlist Items
Corn feted
Other Construction
(streets, houses,
etc.)
I
Request Final
Dedication Inspection
at 100% Complete
Construction
i
Local Municipalities
Involvement
•
Local Inspection '
Local Inspection)
Local Inspection
Occupancy Permit
for Completed Houses
PROJECT
COMPLETE
Occupancy Permit
for Previously
`permitted Homes
CDM
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
PLAN REVIEW AND INSPECTION FLOWCHART
environmental services
2-44 Figure No. 2-2
drainage facility construction costs (sewers, detention basins, etc.) to receive any permits
issued by the District. MSD does not review erosion and sediment control plans.
Construction Management (inspection) services are also provided by MSD. The Construction
Management (CM) Department oversees MSD's own projects as well as inspection of sewer
and drainage facilities for private development projects. There are currently 20 inspectors,
and the 1996 budget includes a total of 25 inspectors to provide increased inspection. At this
staffing level, the CM Department feels that it can provide adequate inspection given their
current tasks. Currently, the average project load is about 100 active developments per day,
but there are significant fluctuations in the load.
Development activities are split into three categories each having a different target effort
level supplied by construction management personnel. First, are the "emergency projects"
initiated by the District. These projects are usually time and material jobs that require and
receive a full-time inspector. The second type of projects are called "contract projects" and
are the non -emergency projects initiated by the District for which full construction
management services are to be provided. According to the CM Department, one construction
inspector would be ideally responsible for three of these jobs at a time, but current staffing
levels require one inspector to carry up to six of these projects.
The final type of projects are called "P-projects" and are the private developments for which
MSD only provides inspection of the sewer and drainage facilities. The target staffing level
is five of these projects per inspector, but a single inspector currently carries up to ten of
these projects. The inspections focus on the sewer facilities assuring that they meet standards
of MSD, Detention basins are given a cursory, visual review to make sure they are built and
that inlet and outlet structures have been supplied according to the approved plans. An
Engineer's certification is required that is intended to ensure that detention facilities are built
according to plan. No attempt is currently made to verify the volume by survey nor are
compaction tests completed for embankments. Inspectors are not responsible for monitoring
the effectiveness or implementation of erosion and sediment control plans. After the
construction inspector is satisfied with the work and as -built plans have been submitted, final
construction approval is granted.
I:9168-044kr.louislsection2
2-45
Another inspection activity executed by MSD is dedication inspections. These inspections are
the final check on sewer and drainage facilities to make sure that MSD's standards are met
before accepting responsibility for maintenance. For private developments, final dedication
means that the remaining escrow funds can be released back to the developer or contractor.
The dedication inspection does not check detention basins because these facilities are not
currently dedicated to the District for maintenance and remain the responsibility of the
property owner.
Issues/Problems
The review and approval of development/re-development plans and the inspection of
drainage facilities for conformance to MSD stormwater standards are the two primary
enforcement mechanisms for the MSD stormwater regulations. The following is a list of
problems associated with the plan review and inspection process:
(1) Some municipalities duplicate reviews which may provide conflicting direction to the
developer or may delay the review process.
(2) MSD review and approval of development plans sometimes does not occur until after
construction is underway.
(3) MSD does not review grading plans or erosion and sediment control plans. However,
erosion and sediment control plans may not be effective and are often not enforced
adequately by the local municipality. The result is that in some instances,
construction may result in grading that is not consistent with final drainage plans and
the developer may be required to some regrading. Deficiencies in erosion and
sediment control may result in clogging of MSD facilities downstream and sediment
damages downstream that are often blamed on MSD.
(4) The calculation of escrows for detention basins is not standardized.
1:8108-06I alollislsection2
2-46
(5)
Engineer certification of detention basin construction may not be adequate to verify
construction in accordance with approved plans. This will have increased importance
if MSD takes over maintenance of detention basins.
(6) Inspection of drainage facilities during construction is inadequate to assure
compliance with MSD standards and criteria because of limited inspection personnel.
(7)
MSD's final enforcement mechanism for non-compliance with stormwater standards is
to withhold sanitary connection permit even though the stormwater and sanitary
components of a development are unrelated.
Discussion of Potential Options/Solutions
The problems associated with plan reviews relate to MSD's authority and the review process
itself or to the implementation of erosion and sediment control for new development.
Problems associated with the MSD review process can be addressed through changes in
internal review procedures. However, problems associated with erosion and sediment
control cannot be solved directly by MSD, because it lacks the specific legal authority to
directly address this issue. The following section discusses potential solutions to these and
other issues relating to plan review.
(1) Duplicate Reviews - There is no practical way to preclude municipalities from
duplicating District reviews. In some instances, municipalities may have more
stringent regulations or may feel more comfortable in conducting their own reviews.
A potential solution for part of this problem is to insure complete and consistent
reviews by the District and then to work with municipalities to build confidence in
this review process. Another option that was considered is to allow municipalities to
conduct reviews in lieu of the District. However, MSD's staff have indicated they do
not want to delegate this review responsibility. A final option is to continue with the
duplicate review process and work more closely with these municipalities to
coordinate review comments and directives to the developer. This approach should
t:8 I08-OO1\st-louislsection2
2-47
be feasible if there is a clear understanding of the stormwater requirements for both
the municipality and MSD.
(2) Timing of MSD Plan Reviews - Municipalities may permit site construction to begin
before MSD's review is completed can result in the necessity for the developer to do
some regrading. This is not a major problem because MSD can still require
modifications after review of drainage plans. In addition, many municipalities
already require MSD approval before permitting construction to begin so that the
timing of MSD's review is not a problem.
(3)
Erosion and Sediment Conk 1s - Erosion and sediment control problems can be
addressed in several ways. The first is for MSD to seek authority to take
responsibility for erosion and sediment control review and enforcement. The second
is for local municipalities to effectively implement and enforce erosion and sediment
controls.
As discussed in Section 2.2.5, the second option of local municipality E&S regulation
was considered preferable. This solution can be effective if certain improvements are
implemented. The first is that MSD must encourage all local municipalities to adopt
Iegal authority for erosion and sediment control. A number of municipalities already
require erosion and sediment controls, but there is no uniform standard across the
District. The second is for local municipalities to conscientiously enforce erosion and
sediment control regulations. Finally, the state must also enforce its NPDES
construction permit program which requires erosion and sediment control plans for
developments over five acres.
To address the erosion and sediment control issue, MSD should implement the second
option which calls for municipalities to enforce erosion and sediment control
measures. MSD should prepare or recommend uniform standards for erosion and
sediment control and encourage municipalities to adopt them. MSD inspectors should
monitor the effectiveness of erosion and sediment control plans at construction sites
and notify the erosion authority if warranted.
I:81 D8-O011sLlouis)mctiun2
2-48
(4) Detention Basin Escrow - Escrow procedures should be adequate to assure that
detention facilities are built according to approved plans, provided detailed review
and inspection of detention facilities are provided. Because escrow calculations for
the detention facilities have a high degree of subjectivity, MSD should standardize
them to make sure that the amount collected is adequate to meet this objective.
(5)
Inspection of Drainage Facilities - MSD staff has indicated that manpower for
construction inspection has not been adequate in the past. Additional staff are needed
to provide the required inspection. If inspection is expanded and additional staff are
added, inspection fees may also need to be increased to cover inspection costs. MSD
should review its inspection process, resources, and manpower needs and obtain
additional staff to provide the required inspection. This should include a complete
review of detention facilities. In reviewing the inspection process, MSD should also
raise fees as warranted to cover all costs.
(6) Enforcement - MSD currently escrows money for the drainage improvements on a
new development as a guarantee that they will be constructed according to plan.
Escrow monies are released only after improvements are accepted by MSD. The Plan
provides for enforcement through the court system. MSD has not pursued this option
because it is cumbersome and costly. Rather, because nearly all developments are
also providing sanitary improvements, MSD has used the sanitary connection permit
to resolve any necessary drainage issues. MSD should review the legality of this
practice and seek additional legal authority for enforcement if necessary.
Even though MSD is not inspecting grading activities, a check should be put in place
to see that the engineer's certification of detention basin construction truly ensures
proper grading and volume of the basin. MSD staff and the TAC suggested that the
District randomly audit the certifications and have the survey and calculations
reviewed by MSD staff. This would increase confidence in certification without MSD
reviewing grading on every basin.
1:81O-OO11scIauis\secuon2
2-49
Recommendations
MSD should implement the following recommendations to address the problems and issues
associated with the plan review process:
Duplicate Reviews
1. Prepare and distribute a plan review/inspection flow chart that defines the steps,
approvals and responsibilities for MSD and the local municipality.
2. Establish coordination/communication procedures with those communities that desire
to conduct duplicate reviews.
Timing of MSD Review
1. Request that communities require MSD stormwater approval before allowing
construction to proceed. The model stormwater ordinance could establish the
required legal authority for this.
Erosion and Sediment Controls
1. Develop a model stormwater ordinance for municipalities that requires erosion and
sediment control plans for all significant development.
2. Prepare or recommend appropriate uniform erosion and sediment control standards.
3. Conduct a series of workshops to educate municipalities, developers and engineers on
the erosion and sediment control requirements, including the state construction
permit.
Detention Basin Escrow
1. Standardize the procedure for establishing escrow requirements for detention basins
and ensure that escrow amounts are adequate for effective enforcement of MSD rules
and regulations.
I:8I08-OO L\. t.louis\secdonz
2-50
Inspection of Drainage Facilities
1. Review inspection and manpower needs and costs to ensure stormwater
improvements are constructed according to plan, including detention facilities.
2. Hire additional staff or contract inspectors to adequately inspect new developments.
3. Review and raise inspection fees as warranted to cover costs.
Enforcement
1. Review the legality of using the sanitary permit to enforce stormwater requirements
and seek additional legal authority, if necessary.
2. Institute a random audit of engineer's certifications of detention basin construction to
verify grading (volume) and construction according to plans.
2.3.2 MAPPING AND DATABASE INFORMATION
The management of stormwater data is crucial to effective planning and management of the
drainage network. Critical information is often stored on map files or databases or in a
Geographic Information System (GIS) which combines mapping and database capabilities.
Policy decisions must be made to determine the types of information that are kept, efforts to
update/verify the data, and the ability to recall and present information.
Objective
Provide timely, comprehensive and accurate data on the drainage facilities in the MSD
service area to effectively plan and maintain the overall stormwater system.
Current Program
MSD maintains a graphic database (map files) with all of the known storm and sanitary
facilities within the District boundaries on an Intergraph Microstation environment. The
l: a 1 aa-O011st.iouis\section2
2-51
District map files are continually updated as development plans are approved by MSD and
as -built plans are submitted by the developer. The following drainage system items are
input into the District database of map files:
• storm sewers
• manholes
• outfalls
• inlets
• detention basin shapes
• detention basin structures
• improved channels
Information is first input after development plans are approved by MSD. This information is
updated after as -built plans have been submitted by the developer. When the information is
supplied on the approved or as -built plans and includes attributes, such as rim and invert
elevations, materials, etc., this information is recorded directly on the map files. Often
attribute information is incomplete, and, thus, information in the map files is also incomplete.
Attribute information is not linked to the facility it is describing as a database but rather is
only visually connected by being placed near to the drainage facility it describes which limits
the GIS type of applications available on the MSD mapping system. MSD has field verified
elevations to be accurate for projects prior to 1977. Newer areas have not been verified and
missing data is thought to exist in the western portion of the County. In addition to the map
layers created by MSD that contain drainage facility information, base maps that include
municipality boundaries, roads, rivers, etc. are received from the County on a monthly basis
and used as a backdrop to the MSD facilities maps.
MSD maintains three other databases pertinent to stormwater concerns. One database
contains all the complaints received from MSD customers. The second database consists of
all the stormwater projects that have been identified to solve particular drainage related
problems. These two databases are linked to the map files and data can be plotted as a layer
on the maps. The third database is for tracking all development projects that are routed
through the District, and is not linked to the MSD map files.
E:8106-001 Lst.l ouisLsecti on2
2-52
Problems/Issues
The following problems are identified with respect to the mapping and database information:
• There are known areas of missing facilities data.
• Facilities data (rim/invert elevations, etc) for projects after 1977 have not been
verified.
• Attributes of the drainage facilities are not connected to drainage facilities in
anything but a visual form which limits the GIS type of applications available to
MSD and possible with their current system.
• There is no comprehensive inventory of stormwater facilities.
Potential Options/Solutions
The following options are presented with respect to resolving the issues listed above.
Missing Facility Data
Local municipalities were asked to identify areas of missing facilities data through the SSMIP
municipality questionnaire. In addition, working maps created for the Watershed
Assessment Report identified sewered areas with missing slope and/or elevations. The
watershed consultants will collect information on drainage facilities that are a part of the
Primary Stormwater Management System (PSWMS) that is to be modeled and this
information will be coordinated with and incorporated into the mapping efforts. To
minimize the amount of missing data for future development projects, the plan review
process could incorporate a standardized check to assure that all pertinent information is
provided on the plans to avoid missing data problems in the future.
I:8108-00IEst,louisle4tion2
2-53
Verification of Facility Data
As mentioned in the preceeding paragraph, drainage facility data will be collected in
conjunction with computer modeling of the MSD watersheds. This collection of facilities data
shall be coordinated with the mapping department and can be used to verify facilities data
for projects after 1977.
Attribute Data and GIS Applications
If MSD plans to use their Intergraph map files as a GIS type of database, the attributes
(slope, elevations, etc.) should be linked to the map elements instead of the current situation
where they are put on a separate layer and positioned near the facilities they describe. The
additional effort to do this for future inputs would be minimal. The effort required to
convert previous entries would be an extensive one-time expenditure, that would likely
include an automated transfer of data that must be manually verified.
Inventory of Stormwater Facilities
MSD mapping personnel have stated that they have the software required to do a facilities
inventory within Intergraph, but have not had the personnel available to become familiar
with the software and complete the task. This task could be undertaken using the MSD
system and software and the inventory information would then be easily updated to include
new facilities as they are built.
RecommendatiQna
The following recommendations provide for resolution of the issues related to mapping and
database information:
(1) Collect missing facilities data that was identified by municipalities in response to a
SSMIP questionnaire and input into the MSD map files.
(2) Verify facilities information collected for the watershed master plans that was
obtained from map file data for projects completed after 1977.
I:s roa-oo».iouisksec,jon2
2-54
(3)
Assess the potential benefits and effort associated with linking facilities data to the
map files in a manner that accommodates GIS type functions that are possible on the
MSD Intergraph mapping system.
(4) Complete an inventory of MSD stormwater facilities using the MSD Intergraph
mapping system.
(5)
Prepare a standard checklist of facility data desired for the MSD map and GIS files
and require all checklist information before plans are approved in the plan review
process.
I:8108-0011st.lcu isluctio n2
2-55
2.4 OPERATION AID MAINTENANCE
The MSD Plan explicitly gives MSD maintenance authority over all drainage facilities.
Operations and Maintenance (O&M) includes those activities required to run the District
stormwater facilities on a daily basis and to keep the drainage system functioning as
designed. Stormwater O&M includes the following services: Operation of flood gate and
flood wall pump stations, emergency response to major rainfall or flooding events, inlet
cleaning, sewer cleaning, debris removal from culverts and open channels, erosion repair,
complaint response, and general repair or replacement of drainage facilities not operating
properly.
Two of the fundamental O&M policy issues are who is responsible for various aspects of
stormwater maintenance and how often should the various maintenance activities be
performed. Detention basin maintenance was a particularly important issue, especially with
the TAC and PAC, and thus one of the following sections assesses this aspect of maintenance
in detail. Another O&M issue that arose was the availability of access necessary to complete
maintenance activities. For each of the above issues, an objective was formulated, the current
situation was assessed, and recommendations were made for changes to MSD policy.
Funding is another key aspect of the maintenance issue. For the most part, Funding issues
are addressed in Section 2.6. Currently, maintenance services are largely determined by the
limited available funding and any increase in service recommended in this section will
require increased funding to implement the upgraded services.
2.4.1 MAINTENANCE RESPONSIBILi i lES AND FREQUENCY
Stormwater facilities only operate effectively if they are properly maintained. Regular
maintenance of the drainage system prevents system failures and decreases the risk of
stormwater damage. Maintenance responsibilities must be clearly outlined among the many
municipalities and agencies that are involved and standards for maintenance frequency are
important to ensure that the drainage system will function properly when storm events
occur.
1:8 108 -00 l ist 3o u islsectia n 2
2-56
Objective
Define maintenance responsibilities and frequency of maintenance goals that ensure proper
functionality of the drainage system across the entire service area.
Current Situation
The levels of maintenance provided vary greatly across the District service area. In many
areas, no ongoing formal system of stormwater maintenance has been established.
Maintenance is provided by MSD only on public property or facilities that have been
dedicated to and accepted by MSD. MSD maintains facilities like street inlets that provide
local drainage as well as major drainageways that convey flows from large areas of the
District. The following paragraphs describe the current maintenance situation for specific
components of the drainage system.
Detention Basins
The responsibility for maintenance of detention basins is currently on the property owner or
homeowners association who have been required to sign a maintenance agreement. In
general, the maintenance has been poor or neglected altogether, and the current maintenance
agreements are generally ineffective for enforcing maintenance requirements. In general,
MSD does not maintain detention basins.
Roadway Culverts
Roadway culverts are currently maintained by the agency or individual responsible for the
road. MSD will provide emergency services to remove significant blockages. There seems to
be no particular problems with this situation although the maintenance frequencies and
standards are not known for the various responsible agencies.
Storm and Combined Sewers
Storm sewers within the Original Area are routinely maintained by the District. In the
Annexed Area, the MSD will only provide emergency service, and the routine maintenance is
either done by the municipality or is not done at all. MSD does not maintain Missouri
1:810 8-0011s[ J ov i sisal on2
2-57
Department of Transportation storm sewers unless they are an integral part of an accepted
storm system. Even in the Original Area, there is no set frequency of maintenance for the
storm facilities. With current budgetary constraints, the level of the routine maintenance has
diminished which reduces the effectiveness of the drainage network.
Inlets and Catch Basins
Same as for storm sewers.
Improved Channels
The MSD will remove significant obstructions to flow and also undertakes measures to
assure the structural integrity of the channel sides and bottoms. This maintenance includes
any fences installed by the MSD that are integral to the improvements.
Natural Channels
Natural channels are not routinely maintained by MSD, but significant obstructions to flow
will be removed. Priority is given to blockages that cause major flooding. MSD will also
undertake emergency control measures when there is a significant threat from flooding or
erosion.
Trench Drains, Swales, Roadside Ditches and Gutters
MSD does not maintain any of these drainage components. Instead, these items are the
responsibility of the property owners or public agency with jurisdiction. The problems
associated with these drainage components are that MSD receives complaints about backyard
ponding that may be due to removal of swales or other regrading activity that MSD does not
regulate and that, in most cases, these components are simply not the responsibility of MSD
to maintain.
Table 2-4 presents a summary example of annual maintenance activities by MSD. This table
indicates that the MSD does only a limited amount of "preventative" maintenance within the
original boundaries of the District. For example, in a one year period (7/1/92 - 6/30/93) the
Maintenance Department cleaned 14,000 inlets and removed debris from 50 miles of creeks.
Conversations with MSD maintenance staff indicate that this type of maintenance work is
L•81O8-OORst.loW section2
2-58
Table 2-4
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Maintenance Activities from July 1992 to June 1993
SECTION I: COMPLAINT RESPONSE
Complaints Received: 17,313
Work Done Units Quantity
Rodding, Auto Ft. 453,156
Rodding, Hand Ft. 349,508
Bucketing Ft. 82,683
Hydro -Flush Ft. 1,328,919
Inlet Clean, Auto No. 5,574
Inlet Clean, Hand No. 5,895
Creeks Cleaned Ft. 267,455
Cave -Ins Filled No. 1,435
Sewers Inspected Ft. 1,568,880
Sewers Crawled Ft. 140,579
Manholes Checked No. 47,462
SECTION II: PREVENTIVE MAINTENANCE
Work Done
nits Quantity
Rodding Ft.
Bucketing Ft. ---
Inlet Cleaning No.
Interceptor Chmbr. Cleaning No. 68
Grit Chamber Cleaning Ft. 45,425
Creek/Channel Cleaning Ft. 7,172
Hydro -Flush Ft. 604,914
Flushing No. 15,010
Sewers Inspected Ft. ---
Sewers Crawled Ft. 49,186
Hauling Debris C.Y. 2,346
Televising Ft. 214,327
Smoke Test FL 45,425
Grouting (Joints) No. 6,062
I:8 l O8- OO 11sL l o u i sH a b l e 2. 4
2-59
decreasing as work crews are constantly responding to emergency or complaint situations.
Staffing for stormwater maintenance has been decreasing due to inadequate funding. In fact,
the Maintenance Department has fewer employees now than it did twenty years ago when it
was only responsible for facilities within the Original Area. The MSD does not have a
specified routine maintenance schedule for drainage facilities. In Annexed Area of the
District, maintenance activities are limited to work in emergency situations such as major
sinkholes, large flow obstructions causing flooding, and extreme erosion damage posing a
serious threat to life or property. The MSD does not currently do any maintenance of
detention basins or drainage structures in detention basins. Overall, the maintenance of the
drainage facilities in the MSD service area is not adequate to ensure a properly functioning
drainage system.
Issue/Problem
Currently, maintenance activities are not adequate for much of the District. In the Annexed
Area, where MSD maintenance is limited, some larger municipalities have stepped in to
provide some routine stormwater maintenance, but many areas lack any routine service.
Among the agencies that have responsibility for maintenance, the schedules and standards
are not known coordinated and some tasks are not completed by any party. The following
list highlights the key problems:
• Maintenance responsibility for drainage is confusing and poorly defined.
• No MSD stormwater maintenance in Annexed Area except for emergencies.
• Some flooding and erosion problems result from lack of preventative maintenance.
• Level of maintenance provided by other agencies is not known.
• Detention basin maintenance is particularly inadequate.
• MSD lacks funding for adequate maintenance.
• Current MSD maintenance resources present logistical challenges to meet the
anticipated level of service.
1 8 I08 -00 I lu.lo u isksectio n 2
2-60
Fotential Options/Solutions
Maintenance Responsibility
The stormwater maintenance efforts in the MSD service area need to be dearly defined,
understood and accepted by all participating and benefitting parties. Options for
maintenance responsibility are:
(1)
(2)
(3)
Full MSD maintenance of all drainage system components
MSD maintenance of certain drainage system components and delegation of
maintenance other components to owners, local municipalities or other agency
Full delegation of maintenance activities for all drainage system components
Option 1 is not advisable because it fails to take advantage of maintenance efforts by other
agencies that are already staffed, equipped and completing adequate maintenance, such as
roadway crossings. Option 3 is also not advisable because there are many maintenance
services provided by MSD for which there is no Iogical replacement. Also, maintenance of
many components of the drainage system is a regional issue affecting different municipalities
and thus requiring regional control to keep the system properly functioning. Option 2 is the
logical choice with MSD delegating maintenance responsibility to those agencies that are
capable and in those cases where there are minimal regional effects. In cases where
maintenance has not been adequate by others and there are regional effects, MSD will need
to take over the maintenance or implement an enforcement mechanism to see that
maintenance is adequate in the future. MSD has traditionally provided certain services such
as inlet and catch basin cleaning that do not have regional services impacts and yet the
public has come to expect these services. The SSMW committees discussed this issue and the
overall question of how far up the drainage system that MSD should have the primary
maintenance responsibility. It was the conclusion of the SSC, TAC and PAC that MSD
responsibility should extend up to the stormwater inlets and catchbasins and extend
downstream to the outlet into one of the three surrounding major rivers. (Mississippi,
Missouri, or Meramec). This is a higher level of service than is provided by most regional
stormwater agencies but is the logical choice given that MSD has the legal authority and
regulates these stormwater system components, and the public expects these services. Swales
1:S 106-00 SLtt.lcuuuecticn2
2-61
and other graded drainage paths will continue to be under local jurisdiction for regulation
and individual owners will have primary maintenance responsibility. Enforcement of swale
maintenance will need to be included in the model ordinance for local municipalities.
Another approach to Option 2 that should be considered is the contracting of certain services
to the local municipalities or private entities that are already staffed to do certain aspects of
stormwater maintenance. This would reduce potentially major increases in the MSD's
staffing and equipment needs. Local maintenance responsibility is often more responsive,
and with this approach, the local governing bodies will be able to take advantage of the
funding arrangements provided by MSD. If MSD provides Annexed Area routine
maintenance, the maintenance staff has indicated that these activities will have to be phased -
in because of the additional manpower and equipment requirements. The MSD will need to
clearly communicate the phasing of maintenance activities so that public expectations can be
effectively managed. Also, the responsibility for drainage maintenance activities that will not
be undertaken by MSD should be clearly communicated through the public information
efforts.
Another key factor to establishing proposed maintenance goals will be funding. Adequate
dedicated funding is required to implement proper maintenance across the District. This is
issue is more fully assessed in Section 2.6.
It is important to define the maintenance responsibility (and potential options) for each
component of the drainage system. Figure 2-3 summarizes the recommended maintenance
responsibility matrix for the various components of the drainage system. The major changes
are for MSD to provide routine maintenance of drainage facilities in the Annexed Area, and
for MSD to provide detention basin maintenance District -wide.
• Detention Basins - Although there is a distinct problem with the lack of maintenance,
it was not originally recommended by the consulting teams that the District
completely take over this responsibility because of liability, access, complaint
potential, and lack of information on the number, size and state of repair of basins in
the MSD service area. Nonetheless, the general public is strongly in favor of MSD
1: 8108-0011u.1ou fsLuc cia n 2
2-62
r
Stormwater Maintenance Responsibility Matrix
Bold Letters indicate changes from the existing situation.
Y= Yes, these services are provided by this agency.
MDOT = Missouri Department of Transportation
Stornnwater Maintenance Service or
Activity
Operation of Gates and Pumps
Emer enc Res onse
Routine Maintenance
Back and Side -yard Swales
Trench Drains
MSD
St.
Louis
Couny
Local
Munic-
ipality
Individual
Property
Owner
MDOT
Remarks
Natural Channels
Improved Channels
Inlets and Catchbasins
Storm Sewers
Detention Basins
Culverts
Roadside Ditches and Gutters
cony
Y
Y
Y
Y
District only removes major obstructions. Other maintenance by
owner.
Services not currently provided in the annexed area.
Services not currently provided in the annexed area.
Routine and aesthetic maintenance would be the responsibility of
the subdivision trustees or owner. District would take over major
and functional/structural maintenance.
Agency or individual responsible for the road maintains culverts
(i.e. MDOT).
Agency or individual responsible for the road maintains roadside
ditches and gutters (i.e. MDOT).
METROPOLITAN ST. LOUIS SEWER DISTRICT
STORMWATER SYSTEM MASTER IMPROVEMENT PLAN
STORMWATER MAINTENANCE RESPONSIBILITY MATRIX
environmental services
Figure No. 2-3
sponsored detention basins, and MSD has indicated that they would like to at a
minimum provide maintenance that ensures the functional/structural integrity of the
basins. If the policy of MSD maintenance of basins is not implemented, the District
should at a minimum, conduct inspections and produce materials that give guidelines
and procedures for maintenance to remedy the current problems. Further, it is
recommended that a new maintenance agreement with associated standards be
executed for all future basins with a fiscally responsible party. This issue is discussed
more completely in Section 2.4.2.
• Roadway Culverts - No changes in the current responsibility arrangement are
necessary, but MSD should become familiar with the standards and frequencies for
maintenance by the various agencies. If any problems develop with the standards of
the various agencies, then the MSD should consider formalizing minimum
requirements.
• Storm Sewers - It is recommended that the MSD take over this maintenance in the
Annexed Area as the funds are allocated. The public has seen these services provided
in the Original Area and is expecting services to be extended into the Annexed Area.
Specific schedules and standards for maintenance should be designated. The
maintenance staff have indicated that these activities will have to be phased -in
because of the additional manpower and equipment requirements. The MSD will
need to clearly communicate the phasing of maintenance activities so that public
expectations can be effectively managed.
• Inlets and Catchbasins - Same as for storm sewers.
• Improved Channels - No changes in the current policy are necessary, but the MSD
should institute regular inspections and formalize minimum requirements for
maintenance.
• Natural Channels - No changes in the current responsibility arrangement are
necessary, but the MSD should periodically inspect the creeks to identify problems
1:8108.00 1Vt.Sou isisectian2
2-64
and necessary maintenance activities where access is available. A minimum channel
width or drainage area will need to be identified to limit inspection efforts to major
systems.
• Trench Drains, Swales, Roadside Ditches and Gutters - No changes in the current
responsibility arrangement are deemed necessary. These items will continue to be the
responsibility of the individual property owner or in the case of roadside drainage,
the responsibility of the public agency providing the road.
Maintenance Frequency
To ensure proper functioning of the drainage network, MSD should upgrade services to
provide preventative type stormwater maintenance with a specific frequency of maintenance
goals. The frequency of routine maintenance (and/or inspections) should be designed to
identify and remedy potential problems before they can cause damage. The needs for
routine maintenance will vary from one location to another and, thus, frequency goals should
include ranges when appropriate. For example, sediment and erosion control and physical
characteristics such as slope and soils can have a major effect on the need for maintenance.
Stormwater maintenance programs from various places around the county were reviewed to
formulate Table 2-5 which outlines routine maintenance program activities and suggested
frequency ranges.
Recommendations
The following recommendations are suggested for implementation by MSD to resolve
problems and issues related to maintenance responsibilities and frequency:
(1) Extend MSD maintenance services to the Annexed Area subject to available funding.
Coordinate with local agencies to define maintenance responsibilities.
(2) Upgrade MSD stormwater maintenance service to preventative levels including a
specific schedule of maintenance frequency and activities.
I: El i08-001tsi.SouisVeetion2
2-65
Table 2-5
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Suggested Maintenance Activities and Frequencies
Maintenance Activity
1. Detention Basin Maintenance
-Inspection
- Structural or erosion repair
- Sediment removal to restore capacity
-Trash and debris removal
-Mowing
2. Culverts
- Inspect for cracks, erosion, diff. settling
- Remove debris, sediment, ice
3. Clean/Flush storm sewers
4. Clean Catch Basins and Inlets
- Remove sediment and debris
5. Improved channels
- Inspect integrity of channel lining
- Remove blockages and repair linings
6. Natural channels
- Inspect integrity of channel side slopes
- Remove blockages and unwanted vegetation,
and perform reshaping and erosion control
7. Roadside ditches **
-Vegetation control
-Remove sediment and reshape as needed
NOTES:
Recommended Frequency
1 time per year minimum
As needed
1 time per 5 - 15 years
2 times per year minimum
2 times per year minimum
(residential mowing ave. = 14/yr)
Once per 5 years
As needed or after major events
Once per 2 - 4 years
Every 1 to 2 years
Every 3 to 5 years
As needed or after major events
Every 3 to 5 years
As needed or after major events
1 to 2 times per year
Every 3 years
**Roadside Ditches are not maintained by MSD but are include in this table because they
play a role in the overall functionality of the drainage system.
1.8108-001 \st.louis\ tab1e2-5
2-66
(3) Incorporate a clear definition of maintenance responsibility in a revised MSD Rules and
Regulations and in the model stormwater ordinance for municipalities.
2.4.2 DETENTION BASIN MAINTENANCE
Detention basins are critical to mitigating the harmful effects of development that cause
flooding and erosion problems. Detention basins hold back the extra runoff produced by
impervious area created by development and release it over a longer period to reduce the
peak flow of runoff generated on a developed parcel. Maintenance of these facilities ensures
that they function as designed and preserves the structural integrity of the basins. Without
proper maintenance of detention basins, increasing stormwater damages are likely to occur.
This section discusses the following issues relative to detention basin maintenance:
• Objective for MSD policy;
• Current situation details and detention basin data;
• Example maintenance activities and schedules;
• Estimated cost of detention basin maintenance;
• Example programs showing varying degrees of regulatory involvement;
• Potential options/solutions; and
• Recommendations for MSD policy
Objective
Define maintenance responsibilities to ensure the structural integrity of detention basins and
that they function as designed.
Current Situation
The issue of detention basin maintenance has been a focal point of much attention in the
course of discussions with the PAC and TAC. Concerns were raised because maintenance
responsibility is not known to the public, not enforced by MSD, and therefore many facilities
are not being maintained. Maintenance is a particular problem for residential basins, because
1:8 [OS-001Ls1.louisLsection2
2-67
they are typically on common ground that is the responsibility of many parties. Currently,
MSD does not maintain any detention basins. The individual -owners, companies, and
homeowner associations are responsible for maintenance but many have no knowledge of the
activities required to maintain a detention pond.
The County first started to require detention basins in the early 1970's. MSD started to
require detention facilities for projects in the early 80's. When MSD took over drainage plan
review responsibility for the Annexed Area in 1989, detention basins became a requirement
throughout the current MSD service area.
Because MSD has not been responsible for maintenance and because many detention basins
were constructed prior to MSD review of plans, the exact number and the condition of
detention basins are not currently known. MSD now tracks the construction of detention
ponds and records some limited information on their digital mapping files. The following
paragraphs give some coarse estimates of the detention basin attributes pertinent to
maintenance that have been used to develop preliminary estimates of detention basin
maintenance costs.
Number of Ponds
The exact number of detention ponds in the District is not known. A recent fee adjustment
report (CDM, 1994) estimated that 2,000 basins exist based on a review of several years of
District permits. This information was obtained from the District's plan review database
(1✓PRTS) that since 1989 has kept track of which developments have detention basins. Since
the last development boom in 1988, the number of new detention facility reviews has
remained fairly constant at a rate of about 150 to 200 per year. Therefore, it is assumed that
approximately 2,200 basins exist within the District as of 1995.
Volume of Ponds
There is currently no comprehensive tabulation of the volume of detention ponds within the
District. As a part of the engineer's calculations made for plan review process, the detention
basin volume would be indicated. The volume of ponds could be inventoried by review of
the plans that come to the District for approval. Based on a sample of 6 ponds, hand picked
1:8I0ffiOO RsiSouiS \stvicri2
2-68
by District personnel to represent the varying conditions, a preliminary estimate of the
average volume of detention basins is 2.1 acre-ft. The range of volumes in the representative
sample selected by MSD was .09 to 7.7 acre-ft.
Areal Size of Ponds
There is also no comprehensive tabulation of the areal size of ponds. The Mapping
Department currently records some basin characteristics as shown on as built plans, but this
practice has only been in place for the last few years. A outline of the basin shape taken
from the as -built plans is drawn onto the facilities map, but there has been no verification
that the as-builts are accurate for detention basins. Based on the same sample of 6 ponds,
and assuming a 3 ft. average depth, a preliminary estimate of the average areal size of ponds
is 0.7 acres. The corresponding range of areal sizes sampled was .03 to 2.6 acres.
Type of Ponds
No tabulation exists of the types of detention ponds constructed within the District. Wet
basins are one type and are designed to have a permanent pool and detention storage is
available above the permanent pool elevation. The other major type of basin is called dry,
because the basin is designed to be dry except during and after storms. The type is
important because maintenance activities differ slightly for each type, but the costs for
maintenance are similar. From discussions with District staff, it would appear that the vast
majority of detention ponds are dry ponds. Given that the costs are similar, it will be
assumed that the typical detention pond in the St. Louis area is a dry pond.
Fxample Maintenance Activities and Schedule
The types of maintenance activities that are important to assure that detention ponds
function properly are listed in Table 2-6. The purposes and approximate schedules of the
maintenance activities are also provided in this table.
I:81 OS-OO 1'4 Iog ie\scctio n2
2-69
Table 2-6
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Maintenance Activities for Detention Basins
Routine Maintenance Purpose Schedule
1. Inspection Insure proper operation of structures Every 2 yrs. minimum
Note erosion, sediment and other problems (wet weather preferred)
2. Debris and Litter Removal Remove potential clogging materials 2 per year minimum
Aesthetics (at time of mowing)
3. Mowing Discourage woody growth and weeds 2 per year minimum
Aesthetics (ave. 14 / yr. for residential)
Non -routine Maintenance
1. Structural Repair/Replacement Repair deteriorating structures or fences
Rebuild settled berm or eroded spillways
2. Sediment Removal
3. Erosion Repair
4. Nuisance Control
5. Vegetation Control
I: 8108 - 00 l is t- ]ou i s ltab l e 2- 5
Every 25-75 years
(varies with materials)
Restore pond capacity Every 5-15 years
(average every 7 years)
Stabilize erosion via regrading or revegetation As needed (assume
on average every 2 yrs.)
Eliminate odor and insect problems As needed
Eliminate rodents burrowing into beams
Remove trees or other vegetation that impede As needed
access or threatens structural integrity of beams
2-70
Cost of Maintenance
Estimates for detention basin maintenance were calculated by the lead consultant team to
range from $2.2 - 13.2 million depending on the Ievel of service to be provided. The higher
end of this range was based on a per detention basin cost from other urban areas which have
much bigger average pond size, thus making this estimate overly conservative. MSD's
Maintenance Department prepared an estimate based on local conditions and available
information and the proposed level of service to be provided. Including a contingency factor
of 30% to account for uncertainty in the number, size, and state of repair of basins, the
Maintenance Department estimated the annual cost for detention basin maintenance is $4
million. Mowing is a maintenance task that could be left to the individual property owners
responsibility as a cost -reducing measure. If mowing costs are removed from the MSD cost
estimate, then the total annual cost, including contingency, for detention basin maintenance is
reduced to approximately $2 million. This estimate is provided as Table 2-7.
Example Detention Basin Maintenance Programs from Other Urban Area
Several urban areas with active stormwater programs were contacted about their approach to
detention basin maintenance. They provide examples of detention basin maintenance
program frequency, responsibility and costs from around the country.
Virginia Beach, VA - The City does not do any maintenance activities for private detention
basins. Instead, they have a thorough inspection program that visits all detention basins
within a 1 to 2 year cycle. If violations of the inspection criteria are found, then a fine is
immediately imposed. In addition, the owner is given a punch list of problems to be
remedied before re -inspection.
Denver Urban Drainage and Flood Control District (DUDFCD) - DUDFCD owns and operates
large regional detention facilities. They contract the routine maintenance of these facilities
(mowing and removal of trash and debris) to local companies on a unit price basis.
DUDFCD calls for detention basins to be routinely maintained three times per year and the
price they pay for this maintenance is from $100 - $150 per maintained acre. They also
�:e�aa oo».m�ionx 2-71
Table 2-7
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Cost Estimate for Detention Basin Maintenance (1)
Maintenance
Activity
Estimated Average
Frequency
Number of
Crews
Equipment
Needed
Materials
Needed
Crew Cost
per Year
(in $1,000)
Cost per 5
Years (in
$1,000)
Material Cost
per Year
''I
Contractual
Services Cost
(in $1,000)
1. Inspection
1 time per year
2
Outfitted Van,
Camera,
Computer,
MISC.
50.5/= 101
20/= 40
2/= 4
2. Debris and
Litter
3 times per year
6
Pick-up, Dump
Truck
Trash bags,
Gloves
50/= 300
131/= 78
4/= 24
3. Mowing
14 times per year for
residential; 3 times per
year otherwise
CONTRACTUAL SERVICES
1500
4. Structural
Repair /
Replacement
Assume 1 per 25 years
2
Air Compressor,
Utility Truck,
MISC.
Construction
Supplies,
Pipe
80/= 160
60/= 120
30/= 60
5. Sediment
Removal
Assume 1 per 10 years
(also includes
revegetation of area)
CONTRACTUAL SERVICES
V500
6. Erosion
Repair
Assume 1 patch of
repair every 5 years
CONTRACTUAL SERVICES
200
7. Nuisance
Control
Assume 1 time per 5
years
CONTRACTUAL SERVICES
100
8. Vegetation
Control
Assume 1 time per 5
years
CONTRACTUAL SERVICES
100
COLUMN SUBTOTALS 1561
238/5= 48 188
2400
Notes:
(1) Source for Estimate is MSD Maintenance Department.
(2) Contingency percentage is higher than is normally used
to account for uncertainty in the number, size, and
condition of detention basins in the MSD service area.
SUBTOTAL INCLUDING MOWING COSTS $3,097,000
CONTINGENCY 30% (2) $929,100
TOTAL COST INCLUDING MOWING
SUBTOTAL NOT INCLUDING MOWING COSTS
CONTINGENCY 30%a (2)
TOTAL COST NOT INCLUDING MOWING
$4,026,100
$1,597,000
$479,100
$2,076,100
BASCOST.XLS
10/2/95 07:20
inspect their facilities for non -routine maintenance problems or sub -standard design. When a
problem or design deficiency is identified, both the design and construction work are
contracted out to local firms. In addition to the facilities they own, DUDFCD will fund the
maintenance of other facilities if monies are available. Their priority list for maintenance
funding is (1) DUDFCD owned facilities, (2) DUDFCD funded or partially -funded facilities,
(3) facilities funded by others. Currently, DUDFCD does fund maintenance in all 3 priority
levels for facilities that are constructed in accordance with DUDFCD requirements.
Lake County, IIlinois - This county -wide stormwater regulating agency in northeastern Illinois
does not maintain nor inspect detention basins. Some individual communities inspect or
maintain facilities to avoid the eyesore of ponds that collect trash and debris, but most just
leave it to the property owner. One inspection of the facility is conducted at the end of
construction to assure that basins are constructed according to the approved plans, but there
are no follow-up inspections to monitor maintenance adequacy. This results in many
unmaintained facilities that are unsightly and ineffective, especially in industrial/
manufacturing areas.
In reviewing of these and other national programs, it was found that more often than not
stormwater regulating bodies do not do maintenance of detention ponds. There are many
proactive stormwater programs that do maintenance of regional detention ponds and there
are some that have extended services to include residential ponds. These programs were
included to show the range of methods employed. The example programs from Virginia
Beach and Denver have worked effectively while the program from Lake County, Illinois has
resulted in many detention basins were very poorly maintained and have become nuisances
to the public.
Potential Options/Solutions
Responsibility for Detention Basin Maintenance
The above programs show a wide variety of responsibility levels for stormwater regulating
agencies. As mentioned earlier, the overall objective for the MSD approach to detention
basin maintenance should be to maintain the structural integrity and design functionality of
1:8108-00I lst.l a ui earct i on2
2-73
the basins. This objective could be met with an inspection program similar to Virginia Beach
without MSD taking the main responsibility for detention basin maintenance. This type of
approach has the benefits of reduced responsibility for the uncertainties in the condition of
basins and reduced liability. Because of these reasons, this inspection -oriented approach was
originally considered for MSD. The disadvantages of this approach are less direct control of
maintenance and less socio-political acceptance because responsibility would remain with the
property owners and enforcement is rarely popular with the responsible parties.
Another maintenance option is for MSD to take responsibility for residential detention basin
maintenance, but continue to require that non-residential detention basins be maintained by
the owner. The non-residential sector has generally more capable of monitoring maintenance
needs and implementing routine and non -routine detention basin maintenance. Also,
enforcement of non-residential owner maintenance is easier because there is a single
responsible party and the basin is usually on their property. In addition, when collecting
stormwater charges or fees, a credit for detention basin maintenance is often preferable to the
non-residential sector and serves as an incentive for proper maintenance. This credit policy
would require an inspection program for non-residential basins that would serve as
enforcement for the maintenance agreements that are executed after basin construction.
The final major option is for MSD to assume primary responsibility for all detention basin
maintenance. The SSMIP committees determined that MSD should have primary
responsibility for residential detention basins and that non-residential basins would continue
to be the individual property owner responsibility.
Extent of Maintenance Service
Even if MSD assumes primary responsibility for detention basin maintenance, there is still
an issue of what kind of services will be provided. Mowing, debris and litter removal
primarily benefit aesthetic considerations and would not be absolutely necessary to achieve
MSD objectives. Delegation of "aesthetic" maintenance to property owners would have the
1:8108-001 l ou lAsecun n2
2-74
advantages of less cost to MSD and fewer complaints due to differing aesthetic standards of
the public.
Recommendations
To resolve the issues and problems related to detention basin maintenance, the following
policies are recommended for MSD.
1. Accept primary responsibility for maintenance of approved residential detention
basins subject to available funding.
2. Continue with the current policy of owner responsibility for non-residential basins
and provide inspection to ensure proper maintenance. If a stormwater charge
(impervious charge) is inacted, offer a credit for owner -maintained non-residential
basins.
3. Limit residential detention basin maintenance activities to those with structural/
functional impacts. Aesthetic maintenance such as mowing should continue to be the
responsibility of the property owners or home owners association.
4. Execute a legally binding and effective maintenance agreement for detention basin
maintenance tasks that are to be maintained by the property owners.
5. Provide guidance to individual property owners on their maintenance responsibilities.
2.4.3 ACCESS AND PRESERVATION OF DRAINAGE PATHS
Another important factor in the implementation of a maintenance program is to provide
adequate access for maintenance personnel and equipment to complete their functions.
Access can be gained through formally acquired easements, conservancy zoning, greenway,
or common ground. MSD also has been authorized by the Plan with the power to enter land
without formal permission in emergency situations when there is a threat to public health or
I:8108-00 L\st.louisLuction2
2-75
well-being. Without proper access, maintenance activities cannot be performed or the cost of
maintenance is increased because long distances must be traversed by crews with equipment.
An associated issue is that formal provision for access preserves the drainage paths that
could otherwise be filled in or modified.
Objective
Provide the necessary access and area to conduct maintenance, inspection, replacement, and
other services related to the MSD's stormwater program as well as to preserve the designated
drainageways.
Current Situations
MSD currently obtains easements that include working space provisions on all storm sewers
and improved channels and inlets that are to be dedicated to MSD. Some older MSD
easements do not provide for adequate working space. Detention basins are also provided
with easements, but these easements are dedicated to the party responsible for maintenance
which is usually the subdivision trustees or homeowners association. Natural channels and
swales are not required by MSD to be in an easement. Access points are also not required
along natural channels, and maintenance staff sometimes have to seek a distant bridge or
culvert crossing for access to move in creek cleaning crews and equipment. Roadside
ditches, gutters, and culverts are generally in a right-of-way and access is not a problem.
Issues /Problems
The issues or problems relate to the need for access, the right of access, and the preservation
of designed drainage facilities or capacity:
• Emergency response requires potential access to natural channels that do not have
formal access provisions.
1: 810 B -00 I Lst.l o u isluc; is n 2
2-76
" R e s i d e n t i a l d e t e n t i o n b a s i n e a s e m e n t s w i l l n e e d t o b e t r a n s f e r r e d t o M S D i f i t t a k e s
o v e r m a i n t e n a n c e .
" T h e l a c k o f e a s e m e n t r e q u i r e m e n t s f o r s w a l e s a l l o w s f o r m o d i f i c a t i o n s t h a t c o u l d
a d v e r s e l y a f f e c t o r o b s t r u c t o v e r l a n d f l o w p a t h s .
P o t e n t i a l O p t i o n s / S o l u t i o n s :
S e v e r a l o p t i o n s a r e a v a i l a b l e t o M S D t h a t w i l l g u a r a n t e e t h e r i g h t t o a c c e s s a n d r e a s o n a b l e
a n d c o n v e n i e n t a c c e s s f o r m a i n t e n a n c e a s w e l l a s p r e s e r v a t i o n o f d r a i n a g e f a c i l i t i e s s o t h a t
t h e y f u n c t i o n a s d e s i g n e d .
T h e p r i m a r y o p t i o n s f o r p r o v i d i n g m a i n t e n a n c e a c c e s s a r e :
" E a s e m e n t s
" S o v e r e i g n I m m u n i t y / E m e r g e n c y A c c e s s a u t h o r i z e d b y t h e P l a n
" C o n s e r v a n c y Z o n i n g / G r e e n w a y o r C o m m o n G r o u n d
R e s i d e n t i a l D e t e n t i o n B a s i n E a s e m e n t s
C u r r e n t e a s e m e n t s a r e g e n e r a l l y s u f f i c i e n t t o p r o v i d e m a i n t e n a n c e a c c e s s . O l d e r e a s e m e n t s
m a y n e e d t o b e r e v i e w e d f o r a d e q u a c y . H o w e v e r , t h e s e e a s e m e n t s w o u l d n e e d t o b e
t r a n s f e r r e d t o M S D i f i t t a k e s o v e r p r i m a r y m a i n t e n a n c e r e s p o n s i b i l i t y . A s s u m i n g
r e s p o n s i b i l i t y f o r m a i n t e n a n c e o f d e t e n t i o n b a s i n s s h o u l d i n c l u d e a r e g i s t r a t i o n p r o c e s s t h a t
i n c l u d e s a r e v i e w a n d t r a n s f e r o f n e c e s s a r y e a s e m e n t s t o M S D . C o o r d i n a t i o n w i t h M S D l e g a l
d e p a r t m e n t w i l l b e r e q u i r e d .
N a t u r a l C h a n n e l s a n d E m e r g e n c y R e s p o n s e
S o v e r e i g n i m m u n i t y a l l o w s M S D t h e r i g h t t o a c c e s s n a t u r a l c h a n n e l s i n e m e r g e n c y s i t u a t i o n s .
B e c a u s e M S D w i l l n o t b e r o u t i n e l y m a i n t a i n i n g n a t u r a l c h a n n e l s , t h i s t y p e o f a c c e s s i s
a p p r o p r i a t e f o r n a t u r a l c h a n n e l s . H o w e v e r , i t d o e s n o t p r o v i d e t h a t a c c e s s p o i n t s w i l l b e
r e a s o n a b l y c l o s e t o t h e s p o t w h e r e m a i n t e n a n c e i s n e e d e d . B u i l d i n g s , f e n c e s , e t c . t y p i c a l l y
h a v e b e e n c o n s t r u c t e d t h a t l i m i t a c c e s s f o r a n d c a u s e c r e w s a n d e q u i p m e n t t o e n t e r t h e
1 : 8 1 0 8 - 0 0 1 1 s t . l o u i s l u c d o n 2
2 - 7 7
streams at distant locations or risk harm to property. Access points would be better
provided by means of easements or common ground for access, and were initially general
easements containing natural streams are not desireable because of an implied expectation
and responsibility to routinely maintain anything in an easement. It is not desireable or
practical for MSD to routinely maintain all natural channels. Thus, it was decided that MSD
should not obtain easements for natural channels, although easements for access to natural
channels may make emergency response more efficient in the future.
Preservation of Overland Flow Paths (Swales, etc.)
Easements, conservancy zoning and common ground are viable options for preserving
overland flow paths, because in varying degrees, they would preclude modifications and
provide the legal tool for enforcement. Zoning and common ground approaches are not a
suitable mechanism for MSD because it is not involved in land use regulation. Easements
would be suitable for MSD, but because swales will not be maintained by MSD and there is
an implied expectation to routinely maintain anything in easement, MSD staff were not in
favor of requiring easements for overland flow paths. The responsibility for overland flow
paths better administered by the local government through its jurisdiction over grading.
Another reason for local control is that filling or obstruction of overland flow paths will
result primarily in very localized drainage problems. Thus, it would be an appropriate option
for local municipalities to obtain easements, convervancy zoning, or common ground to
enforce the preservation of overland flow paths. Easements are probably the most direct
method to preserve overland flow paths and are recommended for incorporation in the
model ordinance for municipalities.
1:81O .00 it t.touisLuctlanz
2-78
1econimendations
The following policy recommendations should be incorporated into MSD's stormwater
management program to resolve issues related to providing maintenance access and
preservation of overland flow paths:
1. Do not acquire easements or other provisions for natural channels as MSD does not
maintain these natural components of the drainage system. MSD should consider
easements or other provisions for access to natural channels, especially in new
developments. However, the Plan provides for access in emergency situations if
easements are not available.
2. Transfer detention basin easements to MSD through a registration process if MSD
accepts basin maintenance.
3. Incorporate requirements for easements for overland flow paths into the model
ordinance for local municipalities, including owner maintenance and enforcement
provisions to assure the overland flow paths are protected.
I:8108,0o Ilst.lauls\secalon2
2-79
2.5 CAPITAL IMPROVEMENTS
The Plan authorizes MSD to construct or reconstruct (by contracts or otherwise) any
improvements, extensions or additions to provide adequate stormwater drainage. Capital
improvements are the structural solutions to alleviate specific drainage problems or to
prevent them from occurring in the first place. Typical examples include replacing an
undersized culvert to pass greater flows, concrete lining of a channel reach that is suffering
from extreme erosion, or constructing a regional detention basin to mitigate flooding.
Capital improvements are usually too numerous or too costly to solve all of the identified
drainage problems immediately after the solutions are proposed in the watershed plans.
Thus, a prioritization procedure is needed to identify the order in which projects are to be
constructed, consistent with available funding. Also, some problems may be more
economically solved by removing structures (buyouts) that are subject to flooding or erosion
damage rather than constructing to address a solution to the stormwater problem.
Current Program
At present MSD undertakes a very limited amount of capital improvement projects that fall
into three categories:
• Operation, Maintenance and Construction Improvement (OMCI) Fund Projects
• Replacement Renewal Projects
• Emergency Projects
Operation, Maintenance, and Construction Improvement (OMCI) Fund Projects
Certain watersheds have a specially assessed ad valorem tax that is used for capital projects
that benefit the particular area. These capital improvements are only done in watersheds that
requested an OMCI tax and all such watersheds are within the original boundaries of MSD.
These projects are generally designed and managed by MSD Engineering with private
contractors doing the construction.
I:810 S-OO 11 st.lou is\uction 2
2-80
Replacement/Renewal Projects
Over time, drainage infrastructure may become degraded to the point of needing
replacement or serious repair. Typical Replacement/Renewal (R/R) activities include:
Routine inlet repair/reconstruction, sewer replacement/rehabilitation, culvert improvements,
and improved stream bank repairs. Currently, these projects are only done in the original
boundaries of the District and they are completed by the Maintenance Department or private
contractors when more efficient. For example, during fiscal year 1993, the Maintenance
Department repaired 2,074 ft. of inlet pipe, 982 square yards of creek banks and 80 square
yards of gabion walls.
Emergency Projects
There are also a small number of emergency projects that involve capital improvements such
as lining a channel where erosion is posing a serious thereat. These projects are done
throughout the entire MSD service area with construction by either the Maintenance
Department or private contractors depending on availability and scope of work. These
projects are prioritized on a 1-9 scale, and only a small fraction of the total projects identified
are done in a given year.
At present, MSD undertakes a very limited amount of capital improvement projects due to
generally inadequate funding. Although there is a prioritization procedure in place, it is not
strictly followed and does not give adequate consideration to the cost of the project or the
number of people benefitted. Another shortcoming of the capital improvements program is
that the Annexed Area of the District does not have anything but emergency projects
available to them. This situation exists because significantly less revenue is collected in the
Annexed Area.
In a report entitled "District -wide Analysis of Stormwater Problems" (MSD, 1989), MSD has
in compiled a comprehensive list of identified stormwater problems and potential
engineering solutions. The total dollar amount to solve all problems was estimated as
$645,000,000 in 1989, and the report mentioned that the Annexed Area would likely have
even more projects than estimated in the report. It should be noted that these estimates did
not consider when and if buyout of the endangered property might be a more cost effective
I:8 l08.001 \sz So u is\section 2
2-81
solution, nor did they assess watershed -wide effects of the solution that is, will the problem
just be moved to another location?
MSD has already initiated the watershed master planning process which will identify projects
and, through computer modelling, insure that they have the desired watershed -wide effects
and do not merely move the problems from one spot to another. This work will build on the
previous capital improvements planning by MSD which sought to solve existing problems.
Previously proposed solutions will be verified as appropriate or new solutions will be
proposed to the problems and the result will be a more refined estimate of the true capital
improvement needs of the District. Master planning allows consideration of proposed
improvements that may solve multiple problems that occur regionally. Finally, the
watershed computer models will allow consideration of future development impacts and
solutions to problems before the problem occurs. More information on watershed master
planning and the testing and screening of alternatives to solve existing and future drainage
problems is contained in the Watershed Planning Framework Report.
2.5.1 PRIORITIZATION OF CAPITAL PROJECTS
As a part of the watershed plans, capital improvement projects will be identified to solve the
flooding and erosion problems in each watershed. Discussion with MSD and experience on
other projects indicates that the number and the cost of potential projects will be significant
and the funding will be limited so that a prioritization procedure is needed to identify the
order in which projects should be implemented. Prioritization of projects related to
stormwater for MSD is an important issue which must balance many factors that determine
the relative importance of capital projects and meet the overall goals and objectives of the
SSMIP.
Objective
Develop a system for ranking capital improvement projects that is objective and cost-efficient,
readily understandable and considers a wide range of benefits.
1: 8108-00 I\st.lo u is\xctl o n 2
2-82
Current Sitjiation
MSD has a priority ranking system for stormwater projects that ranks flooding and erosion
problems on a 1-9 scale based primarily on threat to public safety, property, or vehicular
access. The current MSD prioritization procedure ranks frequent flooding of habitable
structures by overland flow and erosion threatening a habitable structure or significant public
work as the two highest priorities respectively. The lowest priority problems are flooding in
open space and flooding that restricts vehicular access. The ranking system does not
explicitly take into account the number of structures affected nor does it consider the cost of
projects to correct the problems. Also, because all projects are ranked 1-9, there is a minimal
differentiation between projects.
Issue/Problem
Although a prioritization procedure now exists, it is limited by the way costs and benefits are
incorporated into the priority assignment. Two major problems need to be addressed:
• The current prioritization procedure does not give adequate consideration to project
cost and consideration for the number of people benefitted.
• The prioritization procedure should allow for greater differentiation between the
large number of projects identified in the watershed plans.
Potential Options/Solutions
Various methods of prioritization from other urban areas were reviewed and applicable
points for the SSMIP prioritization program are presented in the following sections. Many
approaches have been utilized to rank stormwater related projects that together comprise a
continuum of complexity and detail. The following three categories of prioritization
1:S108-00LLst.1ouis. cUon2
2-83
procedures are described in the following paragraphs and conceptually describe the amount
of detail involved in a particular approach.
• Detailed Benefit - Cost Analysis
• Weighted Benefit Point System with Cost Comparisons
• Simplified Ranking (Low -Medium -High or 1-9)
Detailed Benefit - Cost Analysis
The first option is the detailed benefit -cost analysis. This approach has been used extensively
by federal agencies as a justification for major flood control projects. It requires that all
benefits be given a dollar value and this value is compared to the cost to construct the
project. Usually the dollar value of the benefits is divided by the project cost to yield a
benefit -cost ratio. The higher this ratio, the higher the priority of the project. This procedure
is a very time-consuming, detailed process and the assignment of dollar values to
environmental or aesthetic type benefits is very often subjective and controversial. Also, the
dollar value of certain benefits can become obsolete, such as flood damages when as land -use
changes. On the positive -side, this procedure is comprehensive, precise, and has the best
chance to withstand legal challenges.
Weighted Benefit Point System with Cost Comparisons
The majority of city and county -wide stormwater prioritization procedures that were
reviewed fell into this category. These procedures assign benefit points (instead of dollars) to
each of the types of benefits considered to be important. The benefits list can be quite
comprehensive or only consider a few key features, and undesirable aspects of a project can
be given a negative benefit. Because all benefits are not equally important, certain benefits
are weighted to have a lesser or greater percentage of the total possible benefit points. The
weighting factors are generally determined by stormwater planners. The project cost is then
compared to the weighted total benefit points assigned to the project.
Several methods of comparing benefits and costs have been utilized by other urban
stormwater planners and include: 1) normalized benefit -cost ratios, 2) normalized benefit -cost
difference, 3) incorporation of cost as a negative benefit, and 4) benefit and cost rank
I: 8 109-00nst.lou is\secti on 2
2-84
difference. The first two involve normalization of benefits and/or costs so that both of these
have the same order of magnitude. For example, if project benefits were on a scale of 1 to
100 then each project cost would be divided by a constant so that the highest cost project
would score a 100 for cost. Now the benefits points are compared to the cost points either by
division (No. 1) or by subtraction (No. 2). Method No. 3 simply puts in cost as a negative
benefit and the priority of a project is determined by the sum of the total 'benefits" which
includes costs. Method No. 4 ranks all projects on two lists-- one for total benefit points and
another for total cost. The benefit rank of each project is then subtracted from the cost rank
to yield the priority of the project. For example, if a project ranked 100 out of 100 for total
cost (lowest cost) and 1 out of 100 for total benefits (highest benefits), then the priority score
of this project would be 100 - 1 = 99.
Simplified Ranking
The final category of prioritization procedures are simple rankings. These procedures usually
focus on just a few key benefits (such as reduced home flooding) of a project and do not
have comprehensive consideration of overall benefits. Also, the comparison of cost to
benefits is usually not considered in detail because the simplified ranking is most often used
as a crisis management tool rather than a planning tool. In crisis management, the important
question is "Does this project have to be done now to solve a pressing problem?". Cost is
usually a secondary issue because something has to be done to address the crisis. Lower
priority projects are only addressed when they deteriorate and become a high priority crisis
type of situation.
Evaluation of Options
Overall Prioritization Approach
The SSMIP Committees have discussed the various types of procedures and determined that
a weighted benefit point system with cost comparison is the most appropriate method for the
SSMIP. Detailed benefit -cost analysis is a very time consuming and complex effort with
potentially questionable assignment of dollar values for public health, safety, and other
benefits. The last option of simplified ranking does not give adequate consideration to the
I:8I08-00I lst.lou istuaion 2
2-85
full range of potential benefits and the inadequate consideration makes this approach
inappropriate for the proactive stormwater planning that MSD has initiated in the SSMIP.
Determination of Benefits
In a review of other stormwater master plans, a wide variety of benefits were considered for
the prioritization of projects. Based on experience and review of other urban area
procedures, several factors have been identified which could be considered in the
prioritization of projects by the District:
• Flooding of structures, transportation facilities, and property
• Streambed and bank erosion that threatens structures
• Inclusion of other funding partners
• Development of public multi -use facilities (parks)
• Impediment to implementation (extended road closures, regulatory reviews)
• Environmental impact (Water quality benefit, wetlands, etc)
• Health hazard reduction (usually for CSO areas)
• Safety hazard reduction (icing, drowning, earth stability)
• Community impacts (land acquisition, tax base impact, aesthetics)
• Preventative measures that keep problems from occurring
The assignment of point values is a potentially controversial topic. Final determination of
benefit criteria and point values will be determined and tested in the Pilot Watersheds of
Phase II including feedback from the Phase II watershed committees (public involvement).
The point system should include a comprehensive list of benefits and have enough points
possible to allow differentiation between projects.
Determination of Costs
Of the various stormwater master plans that were reviewed, all used capital costs only in the
calculation of benefit to cost ratio. A more complete approach for costs of structural
alternatives would take into account design and O&M costs because O&M costs can vary
greatly from one type of project to the next. For example, pump stations require much more
maintenance than a replaced culvert. O&M costs can also be incorporated as negative benefit
1:8108-00 ]kt, Icuis'scaion2
2-86
with a qualitative ranking with associated points (i.e., high = -5, medium= 3, low = 0). Land
costs should generally be included in the capital cost unless another source of funds can be
utilized because of multiple -use (parks, etc) or some other factor. MSD has an existing
costing procedure in place that may be too complex for the planning level costs to be
developed in the watershed master plans. MSD will need to identify a simplified list of unit
costs that will be used to calculate project costs for use in the watershed plans and ultimately
the prioritization procedure.
Benefit to Cost Comparison
Almost every priority ranking procedure that was reviewed took a different approach
towards comparing cost to benefit. Of the methods reviewed, MSD staff determined that a
method similar to the one used in Virginia Beach, Virginia would be most appropriate. In
this method, all the projects are ranked for cost and benefit (highest cost = 1, highest benefit
= 1); then the difference between the cost rank and the benefit rank was the priority
indicator. This method is one of the simplest and most understandable. It relies on the
premise that if a project has a high benefit rank and a low cost rank, when compared to the
other projects, then it will be a high priority project. This method does not involve any
normalization of benefits or costs making it that much simpler. There is a loss of magnitude
when simply ranking projects, because a project that is much more expensive can be ranked
next to one with much lower cost thus diminishing the difference between the two projects.
But, because the assignment of benefit scores has a somewhat arbitrary scale already, this is
not a considered to be a major drawback. This method has been tested by MSD and will also
work well with the MSD database system so that the priority ranking system could be
readily updated as needed for new and completed projects, increases in construction coasts,
and other such items.
Recommendations
• Utilize the Weighted Benefit Point System with Cost Comparisons approach to
prioritization.
1:8108- OI\ t.mois\sectioo2
2-87
" U t i l i z e t h e c o s t - b e n e f i t - r a n k - d i f f e r e n c e m e t h o d w h i c h a s s i g n s p r o j e c t p r i o r i t y b y
s u b t r a c t i n g t h e c o s t r a n k f r o m t h e b e n e f i t r a n k f o r e a c h p r o j e c t .
" T e s t a n d f i n a l i z e t h e b e n e f i t p o i n t s s y s t e m d u r i n g t h e P h a s e I I P i l o t W a t e r s h e d
P l a n s .
" G e n e r a t e a l i s t o f s t a n d a r d i z e d p r o j e c t u n i t c o s t s f o r u s e i n t h e c a l c u l a t i o n o f S S M P
w a t e r s h e d p l a n p r o j e c t c o s t s .
2 . 5 . 2 B U Y O U T S
T h e t e r m " B u y o u t s " r e f e r s t o a c q u i r i n g p r o p e r t i e s t o r e m o v e p e o p l e a n d s t r u c t u r e s f r o m a r e a s
t h a t a r e s u b j e c t t o s t o r m w a t e r d a m a g e . B e c a u s e s t r u c t u r a l s o l u t i o n s t o f l o o d i n g a n d e r o s i o n
p r o b l e m s a r e o f t e n v e r y c o s t l y , a c q u i s i t i o n o f t h e s e a f f e c t e d p r o p e r t i e s i s s o m e t i m e s a m o r e
c o s t - e f f i c i e n t a p p r o a c h . B u y o u t s r e q u i r e a d d i t i o n a l c o o r d i n a t i o n a n d c o n s u l t a t i o n w i t h l o c a l
o f f i c i a l s t o d e t e r m i n e t h e e f f e c t s a n d s o c i o - p o l i t i c a l a c c e p t a b i l i t y o f a c q u i r i n g p r o p e r t i e s a n d
l i m i t i n g t h e u s e o f a c q u i r e d p r o p e r t i e s .
O b j e c t i v e
C o n s i d e r a c q u i s i t i o n o f p r o p e r t i e s ( b u y o u t s ) t h a t a r e s u b j e c t t o r e p e a t e d f l o o d i n g o r e r o s i o n
d a m a g e w h e n m o r e c o s t - e f f e c t i v e t h a n o t h e r a l t e r n a t i v e s a n d w h e n s o c i o - p o l i t i c a l l y
a c c e p t a b l e .
C u r r e n t S i t u a t i o n
M S D d o e s n o t c u r r e n t l y c o n s i d e r o r p u r s u e p r o p e r t y a c q u i s i t i o n a s a m e a n s f o r s o l v i n g
s t o r m w a t e r r e l a t e d p r o b l e m s .
I : 8 1 0 8 - 0 0 I l s t . l o u i s l e . t i o n 2
2 - 8 8
Issues /Problems:
Some properties suffer repeated flood damages caused by one or more of several potential
sources; overbank flooding, sewer backups, or Ieakage through basement walls. During the
1993 flood, more than 1000 buildings were flooded in St. Louis City and County. Many of
these properties are located in the floodplains of creeks and rivers within the District. In
some cases, properties are damaged repeatedly from overbank flooding along these
drainageways. Those damages are often covered by insurance through the National Flood
Insurance Program. In some instances, the federal government pays for cleanup or repairs
even when the property owner has neglected to purchase insurance. Other times, property
owners pay for cleanup and repairs themselves.
Solutions to overbank flooding are often channelization, storage, levees, floodwalls or
combinations of these techniques. Within the MSD's service area, capital improvements are
planned in each annual Capital Improvement Program (Cif) that will be constructed for
alleviating flooding conditions. Future watershed plans may also recommend additional
improvements for alleviating existing and potential future flood damages to buildings.
Property acquisition may be less costly than other types of capital projects for alleviating
chronic flood damages and in some instances can be supplemented by state or federal grant
monies.
Often times, the property owner is unaware that a program is available through the National
Flood Insurance Program (NFIP) to acquire buildings damaged during flood disasters. When
made aware of this voluntary acquisition process, the property owner often opts to sell his or
her. property. After floods, buyouts are initiated at the local municipal level through an
application process to the State Emergency Management Agency (SEMA). Typically, SEMA
provides 75% funding, and a matching 25% is funded through HUD community
development block grants. If approved for a buyout, the property is appraised, any
buildings on the property are then removed and the vacant land is deed restricted so that the
property remains open space.
I:810 8-001.s1. ] n u f slucLLo n 2
2-89
After the 1993 floods, numerous properties were acquired in St. Louis and St. Charles
Counties under the buyout program described above. For example, along the River Des
Peres and in Valley Park, about 100 properties were acquired based on a 60/40 cost split
between the grantee (SEMA) and the subgrantee (St. Louis County). According to regional
FEMA offices, all of the disaster -related funding in response to the 1993 flood has been
allocated. Although no disaster -related funds remain from the 1993 flood, a bill known as
the "Riegle Bill", passed as part of the Community Development Act of 1994, dedicates $20
million in FY 1996 and $15 million is subsequent years to non -disaster flood mitigation
activities. States must compete for these funds by submitting an application which describes
the planned use of the funds. The states who receive these funds then distribute the money
to the local municipality who are responsible for conducting flood mitigation activities. These
activities may involve the construction of individual projects or long-term planning.
Regional FEMA staff also indicated that the City and County of St. Louis receive annual
Community Development Block Grant funding other than that described above which could
be used for flood damage mitigation activities.
Potential Options/Solutions:
Options available to the District include (1) maintain the status quo whereby responsibility
and initiatives for property acquisition are relegated to SEMA/FEMA, or (2) increase
activities related to property acquisition including the evaluation of property as an alternative
to capital improvements when evaluating watershed -wide structural solutions.
Recommendations
The following recommendations are based on the recognition that at the federal, state, and
local Ievels, acquisition of properties is often a cost-effective and socio-politically acceptable
solution to repeat flooding and erosion problems.
1. Prepare a written policy that addresses the District's position on the purchase of flood
damaged and flood prone buildings. This policy would be for internal use by District
staff to determine whether buyouts should be considered.
I:6108-0011tt.1ou i slutts9n 2
2-90
2. Work with SEMA to identify local opportunities for using non -disaster grants from
FEMA for conducting flood mitigation activities. This recommendation should include
further investigations by the MSD General Counsel into possible legal and financial
constraints to obtaining these grants.
3. DeveIop an acquisition component to the stormwater management program under the
watershed planning effort which would work in concert with municipal governmental
voluntary acquisition initiatives. This could involve identifying and prioritizing
properties that are economically desirable for acquisition. MSD could also investigate
the eminent domain rights of local government which provides the authority to
condemn property as a means to remove chronically -flooded buildings.
4. Evaluate voluntary acquisition as an alternative to structural and other nonstructural
solutions during the preparation of watershed plans. The evaluation would include
determination of the full economic impact of flood damage reduction benefits versus
costs for buyouts. Costs should include lost tax revenue in addition to capital and
operation and maintenance costs.
1:8108-0011st.I ou iAseaio n 2
2-9 I
2.6 FUNDING
Funding of MSD's stormwater management program is the critical factor for successful
implementation of the program and to provide the level of service expected across the
District. The lack of an adequate, dedicated, fair and equitable funding source is a common
cause for most of the stormwater problems and issues facing MSD. Most, if not at all, of the
proposed solutions and stormwater service improvements, cannot be implemented without
changes in the way MSD customers pay for stormwater services.
This section explores several aspects of the funding challenge facing MSD including:
• A summary of funding problems/issues;
• Existing stormwater expenditures;
• Existing stormwater revenue sources;
• Potential expanded stormwater costs; and
• Potential funding sources and mechanisms.
Several of the viable funding mechanisms are evaluated and discussed and recommendations
are made regarding directions for funding based on feedback from the SSC, TAC and PAC.
Responsibility and Authority
Adequate funding must be obtained to successfully implement and manage a comprehensive
stormwater management program. The Plan specifically empowers MSD to establish rates or
other charges on all real property in the service area to support MSD's management
operation and maintenance of the drainage system.
1:3108-0011st.iouis«ion2
2-92
Objective
To provide a stable, dedicated, equitable, adequate, and implementable source of funding to
support a comprehensive stormwater management program.
Prs2blerrls and Issues
One of the most crucial aspects in establishing a comprehensive stormwater program is
funding. The following problems and issues have been raised through the SSMIP process.
• Current funding is inadequate to provide a comprehensive stormwater program
particularly in the Annexed Area.
• Recent court rulings indicate that increases in funding may require voter approval.
• MSD's "PIan" does not allow bonds without voter approval.
• District -wide revenue bonds are not possible unless direct benefits are District -wide.
• Current stormwater charges that are based on property value do not apply to all
beneficiaries due to tax-exempt status.
• Current stormwater charges based on property value or a flat charge do not allocate
costs according to causative factors such as runoff contribution.
• Current inspection fees may not be adequate to provide the required level of
inspection.
• Some Operation Maintenance Construction Improvement (OMCI) Districts are
overlapping.
• Bonding requires voter approval of more than a simple majority.
Existing Stormwater Expenditures
In conjunction with the SSMIP, the MSD's Finance Department supplied stormwater
expenditure information based on actual figures for fiscal year (FY) 1994 shown in Table 2-8.
(CDM files, 1995). Total capital expenditures for FY 1994 were $14,414,950, which included
replacement/renewal costs of $2,408,250 and operating and maintenance costs of $7,196,400.
1:$198-0011st.louis\section2
2-93
Table 2-8
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
FY 1994 Stormwater Expenditures
FY 1994 Stormwater Expenditures Amount Percentage
Non -Capital Improvement Expenditures
Administration $ 1,463,500 10%
Engineering/Planning 2,413,700 17%
Construction Management 933,100 6%
Operations & Maintenance 7,196,400 50%
SUBTOTAL $ 12,006,700 83%
Capital Expenditures
Replacement/Renewal $ 2,408,250
New Capital Expenditures 0
TOTAL
Source: MSD Finance Department
1:8108-001LsL Iouis\ta61e2-8
2-94
17%
0%
$ 14,414,950 100%
Although replacement/renewal costs can vary considerably from year to year, the recent
seven year average was $2,730,000. The FY 1994 costs appear to be reasonably representative
of typical stormwater program costs for MSD.
Existing$tormwater Revenues
Currently, MSD obtains stormwater revenues from the following sources:
1. Ad valorem taxes
a. Administrative tax- collected District -wide
b. O&M tax- collected in Original Area Only
2. Engineering fees (plan review, inspection, and permits)
3. Stormwater service charge (flat rate)
4. OMCI tax (specially assessed subdistrict tax)- collected only in certain sub -
watersheds of Original Area that have in the past requested such a tax be
levied
5. Miscellaneous income
An ad valorem tax for MSD administrative costs is levied District -wide at a rate of $0.02 per
$100.00 of assessed valuation. This administrative tax is used for both wastewater and
stormwater programs, with the goal of approximately 50% to each program. In addition to
this, the Original Area of the District pays another tax of $0.05 per $100.00 of assessed
valuation that is intended to cover operation and maintenance expenditures. According to
the Plan, the combined taxes used for operation and maintenance cannot exceed $0.10 per
one hundred dollars of assessed value of the property, and any increase must be approved
by a majority of the voters of the District. See Table 2-9 for a summary taxes and charges
collected from residents in the original and Annexed Areas respectively.
Engineering fees are charged for services rendered for plan review, inspections, and permits.
These fees are intended to cover the cost of providing these services. Rates have been set
based on the District's experience of actual costs for these items.
I:8108.00 ilst,louis\uction2
2-95
Table 2-9
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
MSD Existing Stormwater Rates
Amount
Original
Area
Annexed
Area
Intended Use
Flat Rate Charge
$0.24/mo.
X
X
Emergency O&M
Administrative Tax
$0.02/$100 of
assessed value
$0.05/$100 of
assessed value
X
X
Administrative Costs
Stormwater Tax
X
General O&M in original area
Operation, Maintenance &
Construction Improvement
(OMCI) Tax
0-$0.06/$100 of
assessed value (1)
X
Capital Improvements in parts
of original area
(1) OMCI taxes are only levied in sub -district watersheds that have requested the assessment. Some sub -districts overlap so that
max OMCI charge is $0.16/$100 of assessed valuation.
Source: MSD Finance Department
1:8l08- OO I1.st.loultab9& ! 2
2-96
A flat rate stormwater service charge of $0.24 per month is currently charged to all MSD
customers including the Annexed Area. This charge is intended to cover the emergency
response efforts in both the Original and Annexed Area.
OMCI funds are a specially assessed ad valorem tax charged to a watershed or sub -
watershed for capital improvements that benefit that particular drainage area. These funds
are only generated in parts of the District's Original Area that have requested that these
funds be collected. The rate of taxation varies for each OMCI subdistrict up to $0.06 per
$100.00 of assessed valuation, but some of the subdistricts overlap so that the maximum
total OMCI charge is $0.16 per $100.00 of assessed valuation for a small number of properties
that lie within Deer Creek, Black Creek, and Clayton Central OMCI subdistricts. OMCI
funds must be used in the sub -watershed where they are collected for expenses related to
capital improvements. Some of the funds are used to reimburse other stormwater accounts
for services rendered in the planning and design of capital projects and for some
maintenance in the subdistrict. The remainder of funds are used for the construction of the
capital improvements.
Miscellaneous income is primarily interest income, and would include return check charges,
sale of scrap and other reimbursements to the District accounts that are used to pay for
stormwater services.
In conjunction with the SSMIP, the District's Finance Department supplied stormwater
revenue information based on actual figures for fiscal year (FY) 1994 as presented in Table 2-
10 (MSD Finance Department, 1995). The breakdown of major revenue sources shows: 37
percent from the $0.05 tax in the Original Area; 34 percent from OMCI funds and transfers;
16 percent from the $0.02 tax over the entire District; 8 percent from the $0.24 flat rate charge
over the entire District; and 5 percent from various engineering fees. A total of $14.4 million
is currently collected to fund the District's stormwater management program. The OMCI
funds do not represent the total collected for FY 1994, because these taxes are collected for
both sanitary and storm projects (Approximately $7 million total was collected with $4.8
million used for stormwater in 1994). Also, the $2.35 million administrative tax revenue
represents approximately 70% of the total collected which is supposed to be split between
1:8108.0011.1t.I au islecdon 2
2-97
Table 2-10
Metropolitan St. Louis
Stormwater System Master Improvement Plan
FY 1994 Stormw_ater Revenue
FY 1994 Stormwater Revenue
Amount Percentage
Non -Capital Improvement Revenues
Administrative Tax $ 2,352,303 16%
Original Area O&M Tax 5,287,722 37%
Flat Rate Stormwater Charge 1,201,708 8%
Engineering Fees 709,455 5%
OMCI Transfers 2,422,212 17%
Miscellaneous Income 33,300 <1%
SUBTOTAL
$ 12,006,700 83%
Revenues for Capital Improvements
OMCI Funds (after transfers) 2,408.250 17%
TOTAL $ 14,414,950 100%
Source: MSD Finance Department
2-98
l31011-001 \st.louis\ tab2-10
sanitary and stormwater uses. Thus, stormwater activities require using more than 50% of
funds shared with the sanitary side of the MSD activities to fund the current program.
Estimated Costs for a Comprehensive Stormwater Program
With the adoption of Resolution 1884 in February 1989, the MSD Board declared its intention
to provide maintenance services in the Annexed Area. In addition to this, the MSD has
prepared a list of capital improvements projects intended to solve stormwater problems
across the District at an estimated cost of more than $645,000,000. Costs associated with
upgrading the level of service and for extending services into the Annexed Areas have been
prepared by the District Finance Department and are shown in Table 2-11. Stormwater
Expenditures for FY 1999-2004 correspond to the anticipated implementation dates of a
comprehensive stormwater program.
As shown in Table 2-11, the Replacement/Renewal budget is increased by approximately five
times over the current expenditures, and maintenance budgets are eventually increased to
more than three times the current expenditures levels. The most significant changes from
year to year occur in the maintenance costs (Item 3) and the new capital projects (Item 6)
which are to be debt financed with bonds. Increases in maintenance expenditures,
correspond to the phasing of full maintenance activities in the Annexed Areas over a three
year period as the District acquires necessary staff, maintenance yards, and equipment. This
estimate does not however include detention basin maintenance, which was estimated
separately by the Maintenance Department at a cost of $4,000,000 per year including a 30%
contingency to account for the lack of certainty about the number, size and condition of
existing detention basins. New capital improvement costs (Item 6) correspond to the letting
of approximately $ 30 million worth of bonded stormwater projects per year, which is
anticipated to continue for 20 years. The maintenance frequency and level of effort
associated with these projects are not currently known, but the Maintenance Department has
estimated that this funding level would be adequate and would provide
service for above current levels.
I:8 i08-00 LLst louis\section2
2-99
1) Administration
2) Engineering/Planning
Engineering
Construction Management
Environmental Compliance
3) Maintenance
4) Capital Expenditures
5) Replacement/Removal
SUBTOTAL
6) New Capital Improvements
TOTAL
Source: MSD Finance Department
Table 2-11
Metropolitan Sewer District
Stormwater System Master Improvement Plan
MSD Projected Stormwater Expenditures FY 1998-2003
1998-1999
PROPOSED
$3,017,100
3,005,000
1,666,600
0
12,560,300
3,239,900
12,250,000
1999-2000
PROPOSED
$3,644,000
3,342,900
1,732,800
0
17,001,800
3,252,400
12,250,000
2000-2001
PROPOSED
$4,193,900
3,567,900
1,801,600
0
21,650,900
3,810,200
12,250,000
2001-2002
PROPOSED
$4,602,900
3,710,200
1,873,500
3,054,400
22,697,100
1,976,100
12,250,000
2002-2003
PROPOSED
$4,660,900
3,858,200
1,948,100
3,203,200
23,246,900
1,871,600
12,250,000
2003-2004
PROPOSED
$4,935,300
4,012,300
2,026,000
3,813,400
24,093,900
1,968,700
12,250,000
$35,738,900
2,584,400
$41,223,900
5,168,700
$47,274,500
7,753,100
$50,164,200
10,337,500
$51,038,900
12,921,800
$53,099,600
15,506,200
$38,323,300
$46,392,600
$55,027,600
$60,501,700
$63,960,700
$68,605,800
REVREQ.XLS
10R195 10:44
The estimated program costs not including new capital improvements range from $ 35.7
million in the first year to $ 53.0 million in the sixth year. Full maintenance services are
phased in by FY 2001 (year three) and the resulting program cost excluding new capital
improvements in that year is $ 47.2 million. These figures can be used for planning Ievel
estimates of the cost for a comprehensive stormwater program although costs are expected to
change as a result of recommendations in the completed SSMIP watershed plan reports and
may need to be refined at a later date. The net result is a projected increase in stormwater
expenditures from $14.4 million in FY 1994 to anywhere from $38.3 million to $68.6 million
between 1998 and 2004; a significant increase that can only occur if a new source revenue is
identified for stormwater.
Options for Funding Mechanisms
MSD uses several funding sources and funding mechanisms to generate revenue for its
current stormwater program including a general ad valorem tax, a flat rate charge, permit
and inspection fees, and sub -district taxes (OMCI tax) to fund the major stormwater program
components. A number of other funding mechanisms are available and have been used in
other stormwater programs across the country. However, the primary sources of funding are
ad valorem taxes and stormwater user charges.
Funding Program Examples From. Around the Country
The funding question has been addressed by a number of other communities across the
county as a component of their comprehensive stormwater management program planning
and implementation. The following descriptions are provided to highlight their approach to
stormwater funding. Table 2-12, provides a summary of pertinent funding information from
the various stormwater programs described below.
Columbus, Ohio
The City of Columbus had been evaluating the implementation of a stormwater utility from
1989 through 1993. The evaluation resulted in a recommendation to implement an
11108.0011sz.Ioais ,ctioo2
2-101
Table 2-12
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Stormwater Funding Examples
Stormwater Program
Non -Capital
Program Revenue
Source
Non -Capital
Program Rate
Capital Program
Revenue Source
Capital Program
Rate
Comment
Austin, Texas
User Charge
See Capital
User Charge
$3.50/mo/unit
Columbus, Ohio
User Charge
$2.50/month/unit
User Charge
See Non -Capital
Provides very
limited capital
program
Denver, Colorado
User Charge
$2.25/month
Ad Valorem Tax
Unknown
Capital projects by
Denver Flood
Control District
Des Moines, Iowa
User charge
$3.00/month/unit
User Charge
See Non -Capital
Provides very
limited capital
program
DuPage County,
Illinois
Ad Valorem Tax
See Capital
Ad Valorem Tax
$0.20/$100
assessed value
Capital projects
funded through
G.O. bonds and
state grants
Minneapolis,
Minnesota
Sewer User Charge
See Capital
Sewer User Charge
$1.50/mo/unit
Excludes
administrative and
engineering costs
Topeka, Kansas
User Charge
$1.86/month
Not yet addressed
----
1:8108-0011st.louAab9& 12
impervious charge system for supporting stormwater management program costs. The
implementation took place during the summer of 1994 and bills have been mailed since that
time. The system funds all costs for stormwater management within the City of Columbus.
The charge is a flat user charge for each equivalent residential unit (ERU). All residential
properties pay 1 ERU per dwelling unit and all non-residential parcels are evaluated based
upon the quantity of impervious area divided by the average residential unit impervious
area. The typical residential charge is $2.50 per month, which does not include a large
amount of capital projects.
Denver, Colorado
The City of Denver initially established a utility charge based on flat rates for eight user class
categories. Residential properties paid a flat rate per single family home and parcels that
contained multiple dwelling units paid a flat rate based upon whether there were between
two and ten dwelling units or greater than ten dwelling units. The remaining five categories
had flat charges per total acreage on the parcel.
A suit was brought against the City for the system not being equitable in the non-residential
categories. Based upon that suit, the City revised the utility charge system and established
an impervious area/pervious area based user charge. All costs for the City's stormwater
management program are paid for through this charge mechanism. The typical residential
charge is about $2.25 per month. In addition, the Denver metropolitan area falls under the
umbrella of the Denver Urban Flood Control District that is funded by an ad valorem
property tax that addresses larger scale drainage issues and capital projects.
Austin, Texas
The City of Austin initiated a stormwater management program funded by a quasi -
impervious area -based methodology in 1982. In 1992, the City had raised the unit charge per
residential unit from $1.00 to $3.50 per month to provide adequate funding for capital
projects. There were concerns in the community that the charge mechanism was not
equitable due to the categorizations used for non-residential properties. Specifically,
individual categories were charged flat rates per square feet of land area in the non-
residential groupings. The City re-evaluated the user charge system and is considering a
I11S06-041ln louvlsection2
2-103
conversion to an average residential unit (i.e., all residences paying one unit) and all non-
residential parcels paying a fee based upon the quantity of impervious area on each parcel.
All costs for the stormwater management program are paid for through this charge
mechanism.
DuPage County, Illinois
DuPage County is one of the large suburban counties adjacent to Chicago, and has
undertaken a very progressive stormwater/flood control program. The County has utilised
the Illinois Legislation for certain Counties which provides for a dedicated ad valorem tax to
fund a comprehensive stormwater management program. The tax rate is $0.20 per $100 of
assessed value. Their program includes all the major elements (engineering/planning,
maintenance, capital improvements, and public information) that would be in the proposed
MSD program. Municipalities are responsible for local maintenance activities which lowers
the County's total funding needs. Capital improvements are funded primarily through G.O.
bonds that are supplemented by state appropriations. Local municipalities cost share with
the County on planning projects.
Topeka, Kansas
The City of Topeka initiated a stormwater management utility fee in July 1992. The fee is
predicated upon the average residential unit impervious area basis. All single family,
detached residential dwelling units are charged on a three -tiered structure based upon their
impervious area. All non-residential parcels are charged based upon the quantity of
impervious area divided by the impervious area for the average residential parcel. All costs
for the current stormwater management program (excluding capital costs) are paid for
through this charge mechanism. The typical residential charge is $1.86 per month. The
program is in the process of completing a stormwater master plan and the current rate does
not include funding for capital improvement projects.
Des Moines, Iowa
In 1993, the City initiated a stormwater utility feasibility study to determine if a user charge
would provide an additional source of revenue to support the City's Stormwater
Management Program. Substantial capital improvement needs combined with limited
I; 8I c8-OO Ilu.lauis\seuion2
2-104
general obligation bond capacity made an alternate source of revenue imperative. The City is
now in the final steps of implementing its user charge of $3.00 per dwelling per month. The
$3.00 rate does not fund the desired stormwater management program, but represents the
maximum rate the elected officials felt the residents would accept to initiate the program.
Minneapolis, Minnesota
The City of Minneapolis has recently completed a ten year sewer separation project. Its
stormwater program, which consists primarily of O&M, is funded through a sewer user
charge at a rate of $1.50 per dwelling per month. This rate does not support administration
and engineering costs and has limited capital expenditures.
Funding Mechanism Options for MSD
Funding mechanisms used for stormwater management programs across the country are
primarily ad valorem taxes and stormwater user charges. However, the trend has been
toward user fees as opposed to taxes. Based on the available funding mechanisms a number
of mechanisms were identified and considered for MSD including:
Impervious charge
Ad valorem taxes
Sales Tax
Flat Rate Stormwater Fee
Special Assessment Districts
Gasoline Taxes
Subdivision exactions
Fees and permits
Fines and penalties
Fee in lieu of
Connection Fees
Impact Fees
This list represents a combination of funding sources and funding mechanisms. A funding
source represents the origin and basis of the revenue. Funding sources are relatively limited
including taxes, fees or charges, exactions (in -kind services or facilities) and grants. Taxes
and fees or charges provide the bulk of the revenue. Funding mechanisms utilize rules or
guidelines to determine the timing method and rate of revenue collection from a funding
source. Brief descriptions are provided for the funding mechanisms considered for MSD.
1:810 8 -00 I ist.l au i s \uct i on:
2-105
1. Impervious Charge - A user fee for stormwater that is based on the runoff
contribution of each property, which is directly related to the amount of impervious
area.
2. Ad Valorem Taxes - Taxes levied as a fixed percentage of the assessed valuation of all
taxable property.
3. SaIes Tax - A portion of the local sales taxes levied on the exchange of goods and
services that can be used to fund stormwater projects.
4. Flat Rate Stormwater Fee - A uniform charge to all stormwater customers.
5. Special Assessment Districts - A charge in a defined area that pays for a project
which provides benefits across the area. The District OMCI fund is a form of special
assessment based on ad valorem taxation. Typically, assessments are based on an
index of benefits received or services provided (i.e., building frontage, plat area,
impervious area, etc).
6. Gasoline Taxes - A portion of gasoline taxes that may be available for drainage
improvements and maintenance associated with roadways. These funds are currently
used by the County and local municipalities for their drainage -related programs.
7. Subdivision Exactions - Capital projects constructed and funded by new developments
to provide drainage improvements.
8. Fees and Permits - Fees that are charged to recover costs for services such as plan
review and inspection that are limited to the cost of such services.
9. Fines and Penalties - Charges to correct violations of regulations or standards that are
generally limited in scope to the cost associated with corrections and enforcement.
1110 9 -001 Est. So u islo ccd on 2
2-106
10. Fee in lieu of - A pro-rata contribution by individuals or developers for construction
of a drainage improvements by the agency. These fees are paid "in lieu" of
constructing drainage facilities.
11. Connection Fees - Charges for connecting to an existing drainage system that was
constructed with the capacity to carry runoff from a particular development.
12. Impact Fees - Charges made to the developer for upgrading drainage facilities to
handle the increased flows from the development.
Table 2-13 presents a qualitative comparison of these options and assesses each funding
mechanism for reliability, fairness, and adequacy for funding various parts of the stormwater
program. Special assessment districts are generally used for capital improvement
expenditures only and are a viable alternative for that purpose. Permits, fees, fines, and
penalties can be used for the costs of administration, enforcement, and corrections, but are
insufficient to fund either capital improvements or maintenance programs. Fee in lieu is a
viable option for encouraging regional drainage facilities, and should be considered on a
case -by -case basis for regional detention facilities identified in the basin master plans.
Gasoline taxes, subdivision exactions, connection and impact fees can only be used to finance
local maintenance and/or capital improvements that would cover in a piecemeal fashion
what the first three options can cover in a coordinated, District -wide approach. Only ad
valorem taxes, sales tax, flat rate stormwater charge, and the impervious charge mechanisms
can address all aspects of a comprehensive stormwater management program on a District -
wide scale. Each of these mechanisms has been used in other various urban areas to
generate adequate funds for various stormwater programs. These mechanisms also represent
distinct funding sources generating broad based revenues in a different manner and
potentially from different groups of customers. Each of these four major funding sources (ad
valorem taxes, sales tax, flat rate stormwater fee, and the impervious charge) can be
considered to fund all or part of the stormwater management program and are compared in
terms of advantages and disadvantages relative to their application in the District.
!:B k 08-U0lLst.louLe.sealon2
2-107
Table 2-13
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Funding Mechanism Comparison Matrix
Funding Method
District —Wide
Applicability
Equitable
Allocation
of Costs
Reliable
Funding
Source
Requires
Change in
MSD Plan
or State
Legislation (2)
Used for
Capital
Improvement
Costs
Used for
O&M Costs
Used for
Engineering)
Planning
Costs
Impervious Fee
X
X
X
X
X
X
Ad valorem Taxes
X
X
X
X
X
X
Sales Tax
X
X
X
X
X
Flat Rate Stormwater Fee
X
X
X
X
X
Special Assessment
Districts
X
(1)
X
X
X
Gasoline Tax
X
X
X
X
Permit Fees
X
X
Penalties and Fines
X
X
X
Subdivision Exactions
X
X
Fee —In —Lieu —Of Charges
X
X
Connection Fees
X
X
Impact Fees
X
X
(I) Special assessments are equitable in that they allocate costs where there are benefits, but they may not allocate costs according to runnoff
contribution if they are based on assessed valuation like the current OMCI taxes.
(2) The MSD Plan includes an ad valorem tax rate ceiling that is not adequate to support proposed O&M services. Sales tax for
stormwater management is currently an option for counties but not for public agencies like MSD without new enabling state legislation.
Comparison of Major Funding Sources
IMPERVIOUS CHARGE
A user fee for stormwater that is based on the runoff contribution of each property, which is
directly related to the amount of impervious area.
Advantages:
1. All program costs can be supported the impervious charge.
2. Rates based upon annual expenditures can be varied to support the objectives
of the stormwater management program (rates could be varied by watershed).
3. Debt financing can be administered through revenue bonds with the required
vote of the people and will not jeopardize the District's general obligation
(G.0) bonding capacity.
4. Funds generated through the impervious area charge can be spent throughout
the District without geographical designations.
5. Future changes in user charge rate is generally easier to implement than
changes in taxes. However, this advantage may be nullified by court
interpretations of the Hancock Amendment
6. Each parcel pays an equitable portion of the stormwater program costs as
related to the quantity of impervious cover on the property.
1: B I08-00Ila.touislucuan2
2-109
7. Equitable fee adjustments (reduced impervious charges) can be applied to
parcels which relieve the District of costs.
8. All parcels are required to pay the user fee, therefore previously tax-exempt
parcels or partially exempt (i.e., homestead exemptions) will pay an equitable
share of the costs.
9. Eliminates the Administrative (2 cents) and O&M (5 cents) ad valorem taxes.
10. Does not require a Plan amendment to implement.
Disadvantages:
1. Requires additional resources and costs to develop the stormwater utility fee
system and to administer the additional fee.
2. Requires additional accounting/legal resources to monitor delinquent
payments.
3. Collecting delinquent payments is difficult because, there is no stormwater
service to be disconnected if a customer elects not to pay the charge.
4. Can result in an inequitable disbursement of expenditures if there is a wide
variability in project needs (capital) and costs across the District.
5. Charges are not tax deductible.
6. Impervious area concept is sometimes difficult to understand for the customer.
1:81O8-OO1st.!ouis, ci nn2
2-110
AD VALOREM TAXES
Ad Valorem Taxes - Taxes levied as a fixed percentage of the assessed valuation of all taxable
property.
Advantages:
1. Taxes collected can be used to fund all aspects of a stormwater management
program.
2. Monies collected from ad valorem taxes can be used throughout the District.
3. Ad valorem taxes can be used to support the debt service on general
obligation bonds.
4. Because the tax collector has the ability to place a lien on a property for non-
payment of ad valorem taxes, the collection rate for property taxes approaches
100 percent.
5. Rate can be varied by watershed.
6. Tax deductible.
7. Simple rate concept (tax) that is easy to understand by the public/customer.
S. Inexpensive to administer.
Disadvantages:
1. There is no relationship between the assessed value of the properties and the
runoff contribution from the property.
I I08.00 i\st.iouLs. ection2
2-111
2. Tax-exempt and partially tax-exempt properties do not contribute an equitable
share of revenue towards the stormwater management program expenditures.
3. There are generally more constraints to increases in taxes and there may be
ceilings that limit the ability to acquire adequate funding. A plan amendment
may be required to meet revenue goals)
4. When using general obligation bonds MSD's charter requires 2/3 voter
approval through a referendum.
5. If G.O. bonds are used to finance capital projects, they will affect the bonding
capacity of the District.
6. Utility companies pay the most because they own the most property and have
the highest assessed evaluations.
SALES TAX
Sales Tax - A portion of the local sales taxes levied on the exchange of goods and services
that can be used to fund stormwater projects.
Advantages:
1.
The collection of these monies from the entire MSD will allow expenditures to
occur throughout the District.
2. Monies collected from the sales tax can be used for all costs required to
support the stormwater management program.
3. Revenue bonds can be sold based upon the projected receipts from the
dedicated sales tax for stormwater management.
I:R ios-0a 1 W.iouitsec1on2
2-112
4. The general obligation bond capacity will not be jeopardized by the
stormwater management program expenditures.
5. The collection mechanism for a dedicated sales tax for stormwater
management is reliable.
Disadvantages:
1. There is no relationship between the tax placed on goods and services and the
quantity/quality of stormwater discharged from properties.
2. The revenue generated from this source is directly dependent upon the
economic conditions of the area.
3. The legislation necessary to allow MSD to use a dedicated sales tax requires
both state legislature action and vote by the citizens within the District.
4. Legal action is also required by both the County and City of St. Louis to allow
MSD to collect the sales tax.
5. The rate is not variable by watershed.
b. There is likely to be competition for sales tax revenue such as park
improvements.
FLAT RATE STORMWATER FEE
Flat Rate Stormwater Fee - A uniform charge to all stormwater customers.
Advantages:
1. Rate concept is simple and easy to understand.
1:8108-00 itst-louis1seetion2 2-113
2. Administration is simple and less expensive.
3. The flat rate could be varied by customer class and by watershed although
some degree of administrative simplicity and easy understanding is lost.
4. Debt financing can be administered through revenue bonds with the required
vote of the people and will not jeopardize the District's G.O bonding capacity.
5. Does not require a Plan amendment to implement.
6. All developed parcels pay.
Disadvantages:
1. Not tax deductible.
2. Not equitable in that parcels contributing large amounts of runoff pay the
same amount as these contributing small amounts of runoff.
3. Additional effort required to collect delinquent payments.
Example Stormwater Rates
Potential stormwater charges or taxes for the projected FY 2001 stormwater budget were
developed for each of the four funding mechanisms discussed above. Tables 2-14 and 2-15
were prepared by MSD's Finance Department and illustrate how typical customers would be
impacted by the various funding mechanisms. It was assumed that the O&M program (non -
capital) would be funded first with major capital improvements being implemented later in
time after specific projects have been identified in the watershed plans.
I:8108-0011ix.louu. ction2
2-114
Table 2-14 presents typical customer charges to pay for the O&M portion of the
comprehensive stormwater management program assuming a FY 2001 budget of $51,274,500
including $4.0 million for detention basin maintenance and $12.25 million for replacement/
renewal. The program costs in Table 2-14 does not include any major new capital
improvements. Table 2-15 presents customer costs to fund the major stormwater capital
improvements with an average debt service of $29,156,900 per year. This debt service would
be adequate to fund $30,000,000 in projects each year for 20 years using revenue or general
obligation bonds with a 20 year term. These costs are for major capital improvements only
and are over and above the non -capital stormwater program costs in Table 2-14.
Charges for residential customers for O&M range from $2.48/month to $6.88/month for the
impervious charge depending on the size (impervious area) of the residence. Under an ad
valorem tax approach, the range would be $1.16/month to $13.85 depending on the assessed
evaluation. A flat rate would be $10.13/month. Based on total annual taxable purchases in
St. Louis County of approximately $14.6 billion the required sales tax rate would be Q .35%.
The average residential customer would pay the equivalent of $5.28/month (in sales tax
supporting the stormwater program based on annual taxable purchases of $17,910 per year).
Non-residential charges vary significantly. For an average non-residential parcel, the
impervious charge would be $73.81/month; the ad valorem tax $68.01/month; and the flat
rate $10.13/month. Sales tax information was not available.
Small, tax exempt property would pay $22.33/month for the impervious charge; $0.00 for ad
valorem taxes; and $10.13/month for the flat rate. Sales taxes are not applicable.
Table 2-14 shows a significant range for residential property owners from $2.48/month to
$13.85/month depending on the funding mechanism. However, the rates are not
unreasonable relative to other taxes and rates for other services such as water or sewer. On
the other hand, the non-residential charge ranges from $10.13/month for the flat rate to
$73.81/month for the impervious charge. The difference is significantly greater for larger
non-residential parcels. The significance and impact of the tax exempt rate is that tax exempt
properties pay nothing for stormwater under the ad valorem tax basis. In essence, taxable
1:8108-0011st. ouisLsectiun2
2-115
Table 2-14
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Example O&M Program Costs for MSD Customers (1)
Funding Mechanisms and Monthly Charges (in $/month)
Impervious
Charge
Ad Valorem
Tax
Sales
Tax
Flat Rate
Charge
Average Customer Characteristics
Residential
1.670 sf impervious (2)
$4.93
$5.69
$5.28
$10.13
19,980 Assessed Valuation
17.91Q Purchases subject to sales tax
Non -Residential
29,800 sf impervious
238.740 Assessed Valuation
$73.81
$68.01
n/a
$10.13
n/a Purchases subject to sales tax
Other MSD Customer Characteristics
Residential 1 (small)
ZZ sf impervious (2)
4.050 Assessed valuation
$2.48
$1.16
n/a
$10.13
n/a Purchases subject to sales tax
Residential 2 (large)
2,496 sf impervious (2)
$6.88
$13.85
n/a
$10.13
48,64Q Assessed Valuation
n/a, Purchases subject to sales tax
Non -Residential 1 (small commercial)
1.500 sf impervious
49.567 Assessed Valuation
$4.43
$14.12
n/a
$10.13
aLa, Purchases subject to sales tax
Non -Residential 2 (industrial)
1.729.855 sf impervious
$4,242.03
$16,046.49
n/a
$10.13
56.331,489 Assessed Valuation
n/a Purchases subject to sales tax
Non -Residential 4 (small tax exempt)
8.785 sf impervious
$22.33
$0.00
$0.00
$10.13
Q Assessed Valuation
Q Purchases subject to sales tax
Non -Residential 5 (large tax exempt)
259.774 sf impervious
$637.71
$0.00
$0.00
$10.13
0 Assessed Valuation
Q Purchases subject to sales tax
Annual Unit Rate
$2.94
per 100 sf impervious
area
$0.34
per $100 of assessed
valuation
0.35%
of purchases subject
to sales tax
$121.50
per stormwater
account
Notes:
n/a = not available
(1) Rates based on FY 2001 stormwater budget of $51,274,500 which includes $4,000,000 for detention
basin maintenance and $12,250,000 for Replacement/Renewal projects.
(2) Residential rates include a charge for approximately 192 sf of driveways
and sidewalks that is not included in the impervious area listed.
Source: MSD Finance Department
OMRATES.XLS
2-116
I012N5 10:43
Table 2-15
Metropolitan St. Louis Sewer District
Stormwater System Master Improvement Plan
Example Capital Improvement Program Costs for MSD Customers (1)
Funding Mechanisms and Monthly Charges (in $/month)
Impervious
Charge
Ad Valorem
Tax
Sales
Tax
Flat Rate
Charge
Average Customer Characteristics
Residential
1.670 sf impervious (2)
$2.57
$3.33
$2.99
$4.49
19,980 Assessed Valuation
17,910 Purchases subject to sales tax
Non -Residential
29.800 sf impervious
$45.00
$39.79
n/a
$4.49
238,740 Assessed Valuation
n/a Purchases subject to sales tax
Other MSD Customer Characteristics
Residential 1 (small)
672 sf impervious (2)
4.f150 Assessed valuation
$1.06
$0.68
n/a
$4.49
ri/a Purchases subject to sales tax
Residential 2 (large)
2.496 sf impervious (2)
$3.78
$8.11
n/a
$4.49
48.64Q Assessed Valuation
n/a Purchases subject to sales tax
Non -Residential 1 (small commercial)
1.500 sf impervious
$2.27
$8.26
n/a
$4.49
49.567 Assessed Valuation
ri/a Purchases subject to sales tax
Non -Residential 2 (industrial)
1,729.855 sf impervious
$2,612.15
$9,388.58
n/a
$4.49
56.331.489 Assessed Valuation
ri/a Purchases subject to sales tax
Non -Residential 4 (small tax exempt)
8,785 sf impervious
$13.29
$0.00
$0.00
$4.49
Q Assessed Valuation
Q Purchases subject to sales tax
Non -Residential 5 (large tax exempt)
259.774 sf impervious
$392.30
$0.00
$0.00
$4.49
Q Assessed Valuation
Q Purchases subject to sales tax
Annual Unit Rate
$1.81
per 100 sf
impervious area
$0.20
per $100 of
assessed valuation
0.20%
of purchases
subject to sales
$53.88
per stormwater
account
Notes:
n/a = not available
(1) Estimated Capital Improvements Budget = $600,000,000. Rates assume that $30,000,000 worth
of projects is funded each year for 20 years, with an average of debt service = $29,156,900.
Debt service assumes a 20 year payback period on the bonds and District -wide funding.
(2) Residential rates include a charge for approximately 192 sf of driveways
and sidewalks that is not included in the impervious area listed.
Source: MSD Finance Department.
CIP.XLS
2-117
102/75 IQ 49
properties subsidize the tax-exempt properties under the ad valorem tax approach. Under a
flat rate approach, the smaller properties, the residential parcels subsidize all the larger
parcels. Table 2-15 presents similar conclusions for the capital improvement component of
the stormwater program.
Either the Impervious Charge, Ad Valorem Tax or flat rate can provide the required revenue
needed for MSD's stormwater management program. Theoretically, a sales tax approach
could provide the required revenue, but the Finance Department had limited information
was available to develop a meaningful comparison. However, because tax exempted and
non-residential customers typically do not pay significant sales taxes, the residential
customers would be expected to pick up a large component of the cost making the sales tax
charges as high or higher than the flat rate.
Given that these funding mechanisms all can provide the required revenue, the decision for
which is the most appropriate to fund MSD's stormwater program becomes a policy decision
for the Board. This decision must be based on the objectives of the stormwater program and
the funding philosophy of MSD, the impact to MSD's customers, and the ability to
successfully implement the desired funding mechanism.
Feedback from the SSC, TAC, and PAC
To solicit feedback from the public and to develop a recommendation to the Board, funding
sources and funding mechanisms were discussed with the SSC, TAC, and PAC. The funding
issue was discussed with these committees at several meetings in an effort to achieve a
consensus on the most appropriate funding mechanism for MSD. The SSC concluded the
following:
SSC Feedback
1. Any increase in taxes or charges (impervious charge) must be taken to the voters
for approval based on the current political climate and the legal interpretation of
preliminary rulings in pending rate court action.
z:8103-OO1\ t.muis',R;or 2
2-118
2. The impervious charge is the logical funding mechanism for stormwater services
because it fairly and equitably allocates the stormwater program cost based on
the contribution of runoff. All customers would pay for stormwater services.
3. A major issue regarding any charge or tax is the equity of paying for capital
improvements because the capital improvement needs and costs could vary
widely from one area of the District to another. A watershed -based charge for
capital improvements may be the best solution.
4. Given that any increase in taxes must be approved by the voters, the most
important issue becomes the process of taking the increase to the voters for
approval. It will be important to define the public information program, the
magnitude of the increase and the corresponding Ievel of service to be provided,
and the potential for winning voter approval.
TAC Feedback
The TAC, agreed that the impervious charge was the only fair and equitable way to charge
for stormwater services. There was concern with the District's basis for determining the
impervious area on residential parcels, in that not all of the impervious area was accounted
for (driveways are not included) in the assessors data and that non-residential parcels were
in essence partially subsidizing the residential parcels under this scenario. A watershed -
based impervious charge for capital improvements was not a major issue, but was an
acceptable funding approval.
PAC Feedback
The PAC, did not reach a final consensus on the specific funding source nor the funding
mechanism. Several members were not convinced that an impervious charge was a better
approach than taxes. The PAC felt that sales tax as a funding source should be considered in
more detail before being ruled out. Similar to the TAC, concern was also expressed over the
ignoring of some of the residential impervious area (driveways), which, in effect, results in
the non-residential parcels partially subsidizing the residential parcels. The PAC agreed that
O&M should be financed District -wide. The preliminary conclusion of the PAC was that a
1:8106-00I1silouisIsc[ioa2
2-119
simple funding mechanism easily understood by the public would be most appropriate. It
agreed that the simplest mechanism would be a flat rate that could be varied based on the
type of property so that a small residential property owners would not pay the same as large
industrial or commercial property owners. No conclusion was reached regarding how to
fund capital costs.
CONCLUSIONS
H&S/CDM reviewed the feedback and preliminary recommendations from meetings with the
SSC, TAC, and PAC regarding the funding issue. Although there were similarities in
philosophy and conclusions among the committees, the final recommendation requires a
compromise approach to establish an acceptable rate structure for MSD. The
recommendation is based on MSD implementing a rate structure that is fair and equitable;
has been successfully applied in other areas; is legally defensible; is administratively simple
to implement and maintain; and is easy to understand for the average MSD customer.
The two primary funding issues identified by the SSC, TAC, and PAC were the actual
funding mechanism, such as a tax or impervious charge and the geographic area over which
the stormwater cost would be recovered.
The SSC concluded that an impervious charge was the only logical basis for recovering
stormwater costs because it fairly and equitably distributed cost according to runoff
contribution and the benefits received. The SSC felt that maintenance and
replacement/renewal costs should be distributed District -wide, whereas capital cost would
most appropriately be recovered on a watershed basis. The TAC similarly concurred that the
impervious charge was the only fair and equitable way to charge for stormwater services.
The areal distribution for recovering cost associated with capital improvements was not a
major issue, but was an acceptable approach. The PAC concluded that a simple flat rate
should be charged to property with some mechanism to vary the cost between small
residential property owners and large industrial or commercial property owners.
Maintenance and replacement/renewal costs should be recovered through District -wide
charges, but no conclusion was reached on how to fund capital costs.
I:8103-0011st.lo u islsectian2
2-120
Rate Structure
H&S/CDM recommends an impervious area -based charge to recover stormwater costs with a
three -tiered -flat rate structure for the majority of MSD's customers. Under this approach,
95% of MSD 350,000 single-family customers would be charged a flat rate. Smaller properties
in the District would be grouped by impervious area, for example in 1000 square foot
increments, into customer classes with impervious areas up to 3,000 square feet. MSD has
the impervious area of all parcels in its database and can easily group parcels according to
these impervious area classes to determine corresponding flat rates. The resulting three
classes would pay three flat rates based on the average impervious area for that customer
class. This tiered -flat rate approach has been successfully applied in other areas to charge
residential customers for their runoff contribution. This approach also maintains
administrative simplicity in the rate structure and provides customers with a rate concept
that is easily understood. The tiered -flat rate approach based on impervious area also legally
defensible because it is based on actual average impervious area in the user class which does
not very significantly within the class. This rate structure provides tiered flat rates to all
customers with impervious area less than 3,000 square feet.
Under this approach, 75% of MSD's 21,000 commercial customers would be charged
according to their actual impervious area. Although the actual impervious charge basis may
be more difficult to understand than a simple flat rate, the smaller number of customers and
a better ability to understand the concept makes this a reasonable approach for these
customers.
Properties with impervious areas greater than 3,000 square feet, whether residential or
non-residential, would be charged for stormwater services based on their actual impervious
area. These parcels cannot be similarly grouped because of the large variation in impervious
area for these parcels, which ranges from 3001 square feet to millions of square feet, and
because of the resulting wide range of impervious tier or impervious area class. Parcels with
impervious areas greater than 3,000 square feet include some larger residential customers,
although the majority of customers are non-residential customers including industrial and
tax-exempt larger parcels. The actual impervious areas for these parcels vary considerably.
1: 8108-001la.louiskecti on2
2-121
These customers are more appropriately charged according to the actual impervious area on
their property as opposed to a tiered class grouping approach. For example, extending the
flat rate approach to these larger parcels would require a multitude of user classes or would
require much larger grouping that would allow actual impervious areas to vary by
unacceptable amounts in each impervious area class. The result would not be consistent with
the need for a fair, equitable and legally defensible rate structure.
Area Basis For Rate
H&S/CDM recommends a District -wide basis to recover the non -capital stormwater
management program costs such as Operations and Maintenance, Engineering/Planing, and
Replacement/Renewal. Capital cost recovery can be accomplished on a watershed basin.
However, MSD should further evaluate the practicality, administrative costs and customer
acceptance of a watershed based capital improvements costs recovery program.
The two major projected stormwater costs for the future fiscal year 2000 to 2001 from Table
2-11 are Maintenance ($21,659,000) and Replacement/Renewal ($12,250,000). These costs
include significant increases for expanded maintenance service.
The services and benefits associated with these stormwater functional areas are generally
provided system -wide and are not area or watershed specific. Therefore consistent with
discussions with the SSC, TAC and PAC, the charges for these services should be distributed
across the entire District. On the average, all customers generally benefit equally from
maintenance and replacement/renewal services.
Major capital improvements required over and above maintenance and replacement/renewal
have not been specifically identified across the District. MSD is in the process of preparing
watershed master plans which will identify specific capital improvements by watershed.
Because these capital improvement needs are likely to vary considerably by watershed, MSD
should consider watershed/based charges to pay for these improvements. For example, the
intensely developed areas with many problems will likely have more capital improvements
needs than developing areas with few existing problems.
1: 8 l 0 8.00 l lsil a u islstctio n 2
2-122
The watershed basis should be defined by seeking a balance of capital improvement
needs and administrative simplicity after the watershed master plans are completed and the
long term capital improvement costs have been identified. The watershed basis
could be defined by major river basin such as the Mississippi or Missouri rivers or could
be reduced to smaller watershed such as Caulks or Gravoiscreeks, similar to the OMCI
subdistricts in the original area. The capital improvement watershed -based cost recovery
issue should be addressed in the future after MSD has identified required capital
improvement costs and priorities. The areal basis for recovering capital improvement costs
does not affect the funding mechanism or area basis for the other stormwater cost or
programs including maintenance and replacement/renewal.
Recommendations
1. Present the results of the funding analysis to the Board, specifically explaining the
conclusions of the SSC, TAC and PAC.
2. Proceed with a funding scenario for non -capital improvement stormwater cost that
include a tiered -flat rate for the majority of MSD's customers primarily residential
customers, and an actual impervious charge basis for larger parcels, primarily non-
residential customers. The breakpoint between the flat rate and actual pervious
charges should be determined by analyzing the distribution of impervious area for all
MSD customers by major land use categories. Preliminary information provided by
the District indicates that 3,000 square feet would be a logical transition point between
the flat rate and actual impervious charge.
3 Collect revenues for the non -capital components of the stormwater management
program on a District -wide basis. Collect future capital improvement revenues on a
watershed -basis to be determined upon completion of the watershed master plans.
4. Initiate the PI & I Program in preparation for a referendum on the funding
mechanism as soon as is practicable.
I: 8108-0011a.la u is\union?
2-123
3.0 IMPLEMENTATION OF STORMWATER MANAGEMENT PROGRAM
Phase I of the SSMIP focuses on what MSD is doing now in the area of stormwater
management and identifies what should be done to provide comprehensive stormwater
management service to the residents of the District. Section 2 recommended a number of
changes in the way stormwater should be addressed in terms of defining MSD stormwater
policy and development or modification of the Districts Rules and Regulations that govern
stormwater. This section presents the key issues that must be addressed and the steps that
must be taken to implement a comprehensive stormwater master plan throughout the
District.
The "Implementation" of MSDs stormwater management program must address four major
components critical to its success:
Legal authority/rules/regulations
• Planning tools
• Funding
Adoption of the stormwater program
This section discusses MSDs approach to carry out each of these components and identifies
any unresolved issues or action items required for the SSMIP to move forward.
3.1 LEGAL AUTHORITY, RULES AND REGULATIONS
MSD's two principal means for implementing its stormwater program are statutory mandates
in its Charter (PIan) dated February 9, 1954, and design standards listed in Chapter 4 of the
Rules and Regulations and Engineering Design Requirements For Sanitary Sewage and Stormwater
Drainage Facilities dated December 1993. As discussed in Section 1, the Plan grants broad
powers which are sufficient to implement a stormwater management program by the District.
Therefore, MSD has adequate existing legal authority to enact the stormwater management
program as currently envisioned. However, future modifications to the program that might
I;8l611-001\.Louiecio,i3
3-1
include a major water quality emphasis or changes in responsibilities would require further
legal review.
MSD's Rules and Regulations, which are required by ordinance, provide the mechanism for
enforcement of MSD's the design standards and criteria. Section 2 recommended certain
changes to the Rules and Regulations, which will need to be adopted by ordinance to be
legally enforceable. Once the Rules and Regulations are updated and adopted by MSD, they
may become inconsistent with existing local municipal rules or ordinances. In these cases,
the local municipalities will be required to update their ordinances and rules accordingly.
3.2 PLANNING TOOLS
Several planning tools or products are required to facilitate implementation of the stormwater
management program. The Watershed Planning Framework Report provides the technical
information and guidance to develop "Watershed Plans" across the district. The watershed
plans will identify the specific stormwater system improvements to address existing and
future problems. This Policy and Standards Report establishes the overall approach to
comprehensive stormwater management, while the Watershed Assessment Report and the
individual Watershed Plans provide the background information and the specific system
improvements that are required. These documents should be adopted by MSD and their
recommendations and requirements must be conveyed to all appropriate users such as local
municipalities, engineers, and developers.
Section 2 identified areas of MSD's Rules and Regulations that should be updated to be
consistent with the goals and objectives of the stormwater program. MSD should review and
update the Rules and Regulations, adopt and distribute them to users in the District. In doing
so, MSD should consider breaking them up into two separate documents that would separate
stormwater from sanitary. This would improve their useability and focus their information
for both the stormwater and sanitary programs. Development of updated rules will also
require appropriate information exchange and education of users such as engineers and
developers.
L8108.0011szmu
3-2
3.3 FUNDING
Section 2 presented the results of funding discussions with MSD staff, the SSC, TAC and
PAC. The stormwater program can only be implemented if an adequate, dedicated and
reliable source of funding is provided. MSD must identify and implement a source of
funding to carryout its comprehensive stormwater management program.
In reviewing the existing MSD stormwater program, a number of recommendations were
made to improve and expand the level of service provided. These enhancements to the
program will require additional staff, equipment and construction dollars. MSD should
develop detailed budget projections to carryout the additional inspection, expanded
maintenance, improved response times, and required system improvements. This "cost of
service" analysis would serve as the basis for implementing a new source of funding for the
stormwater program.
The MSD Board should consider the funding options proposed and evaluated by the SSC,
TAC and PAC and should adopt an appropriate funding source to implement the stormwater
program. Any new funding options appear to be constrained by the Hancock Amendment.
This constraint may require potential state legislation or local voter approval to implement a
new funding source. The funding mechanism must also consider the potential modification
or reorganization of the District as is being considered by Confluence. Pending the final
outcome of the Confluence study, MSD should consider moving forward with a referendum
that would enable it to implement a new funding source for its stormwater program. The
MSD board should consider and act on the funding issue as soon as it is reasonably
practicable.
3.4 ADQIITICILQEMaamenEhauldANAGEmENLERaczam
The final component of implementation of the stormwater management program is its
adoption and application across the District. The process for its adoption must be primarily
through a Public Involvement and Information (PI&I) program that educates those
individuals or agencies about the objectives, policies and requirements of MSD's stormwater
L•B IaS-0p 11stioolAseaion3
3-3
I
program. In addition, Iocal municipalities must also establish the appropriate legal authority
to ensure the implementation of the program.
MSD is in the process of preparing a PI&I plan to address these and other issues. However,
a major focus of the PI&.I plan must be to educate those individuals associated with
stormwater across the District. This focus should include various methods of education and
technical information exchange to reach elected officials, municipal engineers, consultants and
developers to explain the requirements of MSD's stormwater management program. In
addition to newsletters, MSD should consider special mailings and technical workshops to
explain the changes in how stormwater will be managed in the future.
The other important aspect of adoption of the stormwater program is the need to establish
the appropriate legal authority at the Iocal level. This issue was discussed with the SSC,
TAC and PAC to determine the most appropriate approach. It was concluded that MSD
should establish the minimum standards and technical guidance for stormwater management
that would apply across the District, but that each municipality would adopt its own
ordinances/rules for enforcement.
Through the development of its stormwater management program, MSD has established the
policy for stormwater management across the District. In this leadership role, MSD will
provide the direction and requirements for municipalities engineering, developers and
contractors relative to stormwater planning design and construction. MSD should prepare a
model stormwater ordinance for adaption local municipalities to further assist in the
implementation of its stormwater program. The model ordinance will facilitate a local
education process through, its Development and Adoption will further define authority,
requirements and enforcement responsibilities, and can be structured to include other
stormwater-related issues such as erosion and sediment control, grading and floodplain
regulation that are outside of MSD's authority.
L 6106-00I\alouisyectiony
3-4
I
I
I
I
I
I
I
f
i
i
I
i
N
N
9
i
s
3S
The following steps are required for implementation of MSD's comprehensive stormwater
management program:
1. Adopt the Policies and Standards Report and the Watershed Plans as they are
completed.
2. Initiate the technical information transfer component of the PI&I program.
3. Adopt an appropriate funding mechanism for the non -capital components of
the stormwater program and initiate steps for a voter referendum.
4. Devise the existing MSD stormwater ordinance to reflect recommended policy
and standards changes.
6. Prepare a model stormwater ordinance for local municipalities and assist in
adoption of the model ordinance.
1:1108-00.11,stiottlEuectiod
3-5
I
4.0 REFERENCES
Black & Veatch, 1993, Report on Alternative Rate Structures for the Metropolitan St. Louis
Sewer District Fiscal Year 1994.
Camp Dresser & McKee, Inc., August 11, 1994, Drainage Master Plan - City of San Marcos -
Volume 1 - Report.
Camp Dresser & McKee, Inc., Environmental Engineers, Scientists, Planners & Management
Consultants, August 1990, Stormwater Management Plan - Volume 1: Main Report - Henrico
County Department of Public Works.
Camp Dresser & McKee, Inc., November, 1994, Stormwater Impervious Charge Fee
Adjustment Program, Metropolitan St. Louis Sewer District.
Camp Dresser & McKee, Inc., Program Manager in association with Woolpert Consultants,
Inc., and Wilson & Associates, Inc., January 1992, City of Cincinnati Proposed Stormwater
Management Plan.
Donohue & Associates, Inc. Engineers & Architects, 1981, Storm Water Management Plan.
DuPage County Stormwater Management Committee, September 1989, DuPage County
Stormwater Management Plan.
Federal Emergency Management Agency, 1983, Further Advice on Executive Order 11988
Floodplain Management, Interagency Task Force on Floodplain Management.
Interagency Floodplain Management Review Committee, June 1994, A Blueprint for Change,
Sharing the Challenge: Floodplain Management Into the 21st Century,
l:8108.00 I1st.l o u\u ct 4
4-1
3.5 SUMMARY Op ]MPLEMENTATION RECOMMEND ATTON9
The following steps are required for implementation of MSD's comprehensive stormwater
management program:
1. Adopt the Policies and Standards Report and the Watershed Plans as they are
completed.
2. Initiate the technical information transfer component of the PI&I program.
3. Adopt an appropriate funding mechanism for the non -capital components of
the stormwater program and initiate steps for a voter referendum.
4. Devise the existing MSD stormwater ordinance to reflect recommended policy
and standards changes.
6. Prepare a model stormwater ordinance for local municipalities and assist in
adoption of the model ordinance.
1:8 I O 8 -OO 1 ‘st.l ou is Ise cti o 03
3-5
program. In addition, local municipalities must also establish the appropriate legal authority
to ensure the implementation of the program.
MSD is in the process of preparing a PI&I plan to address these and other issues. However,
a major focus of the PI&I plan must be to educate those individuals associated with
stormwater across the District. This focus should include various methods of education and
technical information exchange to reach elected officials, municipal engineers, consultants and
developers to explain the requirements of MSD's stormwater management program. In
addition to newsletters, MSD should consider special mailings and technical workshops to
explain the changes in how stormwater will be managed in the future.
The other important aspect of adoption of the stormwater program is the need to establish
the appropriate Iegal authority at the local level. This issue was discussed with the SSC,
TAC and PAC to determine the most appropriate approach. It was concluded that MSD
should establish the minimum standards and technical guidance for stormwater management
that would apply across the District, but that each municipality would adopt its own
ordinances/rules for enforcement.
Through the development of its stormwater management program, MSD has established the
policy for stormwater management across the District. In this leadership role, MSD will
provide the direction and requirements for municipalities engineering, developers and
contractors relative to stormwater planning design and construction. MSD should prepare a
model stormwater ordinance for adaption local municipalities to further assist in the
implementation of its stormwater program. The model ordinance will facilitate a local
education process through, its Development and Adoption will further define authority,
requirements and enforcement responsibilities, and can be structured to include other
stormwater-related issues such as erosion and sediment control, grading and floodplain
regulation that are outside of MSD's authority.
I:B l QB-00I1silauieisection3
3-4
3.3 FUN -DING
Section 2 presented the results of funding discussions with MSD staff, the SSC, TAC and
PAC. The stormwater program can only be implemented if an adequate, dedicated and
reliable source of funding is provided. MSD must identify and implement a source of
funding to carryout its comprehensive stormwater management program.
In reviewing the existing MSD stormwater program, a number of recommendations were
made to improve and expand the level of service provided. These enhancements to the
program will require additional staff, equipment and construction dollars. MSD should
develop detailed budget projections to carryout the additional inspection, expanded
maintenance, improved response times, and required system improvements. This "cost of
service" analysis would serve as the basis for implementing a new source of funding for the
stormwater program.
The MSD Board should consider the funding options proposed and evaluated by the SSC,
TAC and PAC and should adopt an appropriate funding source to implement the stormwater
program. Any new funding options appear to be constrained by the Hancock Amendment.
This constraint may require potential state legislation or local voter approval to implement a
new funding source. The funding mechanism must also consider the potential modification
or reorganization of the District as is being considered by Confluence. Pending the final
outcome of the Confluence study, MSD should consider moving forward with a referendum
that would enable it to implement a new funding source for its stormwater program. The
MSD board should consider and act on the funding issue as soon as it is reasonably
practicable.
3.4 ADOPTION OF THE STORMWATER MANAGEMENT PROGRAM
The final component of implementation of the stormwater management program is its
adoption and application across the District. The process for its adoption must be primarily
through a Public Involvement and Information (PI&I) program that educates those
individuals or agencies about the objectives, policies and requirements of MSD's stormwater
I:8108-00I Lst. iou isksectio iJ
3-3
include a major water quality emphasis or changes in responsibilities would require further
legal review.
MSD's Rules and Regulations, which are required by ordinance, provide the mechanism for
enforcement of MSD's the design standards and criteria. Section 2 recommended certain
changes to the Rules and Regulations, which will need to be adopted by ordinance to be
legally enforceable. Once the Rules and Regulations are updated and adopted by MSD, they
may become inconsistent with existing Iocal municipal rules or ordinances. In these cases,
the local municipalities will be required to update their ordinances and rules accordingly.
3.2 PLANNING TOOLS
Several planning tools or products are required to facilitate implementation of the stormwater
management program. The Watershed Planning Framework Report provides the technical
information and guidance to develop "Watershed Plans" across the district. The watershed
plans will identify the specific stormwater system improvements to address existing and
future problems. This Policy and Standards Report establishes the overall approach to
comprehensive stormwater management, while the Watershed Assessment Report and the
individual Watershed Plans provide the background information and the specific system
improvements that are required. These documents should be adopted by MSD and their
recommendations and requirements must be conveyed to all appropriate users such as local
municipalities, engineers, and developers.
Section 2 identified areas of MSD's Rules and Regulations that should be updated to be
consistent with the goals and objectives of the stormwater program. MSD should review and
update the Rules and Regulations, adopt and distribute them to users in the District. In doing
so, MSD should consider breaking them up into two separate documents that would separate
stormwater from sanitary. This would improve their useability and focus their information
for both the stormwater and sanitary programs. Development of updated rules will also
require appropriate information exchange and education of users such as engineers and
developers.
1:8 ]08-001\st.lcuisls,ction3
3-2
4.0 REFERENCES
Black & Veatch, 1993, Report on Alternative Rate Structures for the Metropolitan St. Louis
Sewer District Fiscal Year 1994.
Camp Dresser & McKee, Inc., August 11, 1994, Drainage Master Plan - City of San Marcos -
Volume 1 - Report.
Camp Dresser & McKee, Inc., Environmental Engineers, Scientists, PIanners & Management
Consultants, August 1990, Stormwater Management Plan - Volume 1: Main Report - Henrico
County Department of Public Works.
Camp Dresser & McKee, Inc., November, 1994, Stormwater Impervious Charge Fee
Adjustment Program, Metropolitan St. Louis Sewer District.
Camp Dresser & McKee, Inc., Program Manager in association with Woolpert Consultants,
Inc., and Wilson & Associates, Inc., January 1992, City of Cincinnati Proposed Stormwater
Management Plan.
Donohue & Associates, Inc. Engineers Sr Architects, 1981, Storm Water Management Plan.
DuPage County Stormwater Management Committee, September 1989, DuPage County
Stormwater Management Plan.
Federal Emergency Management Agency, 1983, Further Advice on Executive Order 11988
Floodplain Management, Interagency Task Force on Floodplain Management.
Interagency Floodplain Management Review Committee, June 1994, A Blueprint for Change,
Sharing the Challenge: Floodplain Management Into the 21st Century.
L'8108-001141Mil a4
4-I
The Lake County Department of Planning, Zoning and Environmental Quality, URS
Consultants, HDR Engineering, March 1990, Lake County Comprehensive Stormwater
Management Plan.
Metropolitan St. Louis Sewer District, 1992, Standard Construction Specifications for Sewers
and Drainage Facilities.
The Metropolitan St. Louis Sewer District, 1993, Rules and Regulations and Engineering
Design Requirements for Sanitary Sewage and Stormwater Drainage Facilities - Ordinance
Nos. 7691, 9030, 9033, and 2119.
Moore, Jamie W. and Dorothy P. Moore, 1989, The Army Corps of Engineers and the
Evaluation of Federal FIoodplain Management Policy, University of Colorado - Institute of
Behavioral Science.
St. Louis County Department of Planning, Joseph A. Cavato , Director of Planning, August
1991, The Zoning Ordinance of St. Louis County, For the Unincorporated Part of St. Louis
County.
St. Louis County Department of Planning, Donald E. Clark, Director of Planning, June 1995,
The Subdivision Ordinance of St. Louis County, For the Unincorporated Part of St. Louis
County.
Ven Te Chow, David R. Maidment, Larry W. Mays, McGraw-Hill Publishing Company,
1988, Water Resources and Environmental Engineering.
W. Joseph Shoemaker, Edward J. Krisor, J. Jay Shoemaker, L. Scott Tucker, The Urban
Drainage and Flood Control District.
I:8108-O0 Sut.lou\secz4
4-2