Managing Stormwater
in Your Community
A Guide for Building an Effective
Post-Construction Program
CENTER FOR
WATERSHED
PROTECTION
EPA Publication No: 833-R-08-001
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July 2008
Managing Stormwater
in Your Community
A Guide for Building an Effective
Post-Construction Program
CENTER FOR
WATERSHED
PROTECTION EPA Publication No: 833-R-08-001
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Managing Stormwater in Your Community
A Guide for Building an Effective Post-Construction Program
David J. Hirschman, Center for Watershed Protection, Inc.
John Kosco, PE, Tetra Tech, Inc.
Acknowledgements
The authors would like to acknowledge the substantial contributions and guidance from Nikos Singelis, U.S. EPA
Office of Wastewater Management. Ted Brown from Biohabitats Inc. and Tom Schuelerfrom Chesapeake
Stormwater Network also provided critical review of the document and input and content for various sections.
Many other Stormwater professionals helped to improve this document by reviewing various drafts, providing
program information, and providing content for specific sections. We would like to acknowledge their time, effort,
and insights:
Michael Beezhold, City of Lenexa, KS
Rob J. Beilfuss, City of Lenexa, KS
T. Andrew Earles, Wright Water Engineers, Inc
Jack Faulk, U.S. EPA, Office of Wastewater Management
Sally Hoyt, Biohabitats, Inc.
Steve Hubble, Stafford County, VA
Tom Jacobs, City of Lenexa, KS
Jonathan E. Jones, Wright Water Engineers, Inc.
Lisa Nisenson, Nisenson Associates
Fernando Pasquel, Michael Baker, Inc.
Robert D. Patterson, North Carolina Department of Environment and Natural Resources
James Pease, Vermont Department of Environmental Conservation
Lynn Richards, U.S. EPA, Office of Policy, Economics, and Innovation
Jennifer Zielinski, Biohabitats, Inc.
Local Stormwater managers in 94 communities who responded to the post-construction research tool.
Various staff from the Center for Watershed Protection and Tetra Tech assisted with the technical content and
administrative tasks associated with the guide:
Center for Watershed Protection, Inc.
Lindey Brown, Karen Cappiella, Deb Caraco, Greg Hoffmann, Lauren Lasher, Mike Novotney, Chris Swann,
Laurel Woodworth
Tetra Tech, Inc.
Garrett Budd, Jim Collins, Martina Keefe, Marti Martin, Kristin Schatmeyer, Regina Scheibner, Christy Williams
Credits for Cover Photos
Albemarle County, Virginia
Sanitation District #1 of Northern Kentucky
Greg Hoffmann
Bernadette DeBlander
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Foreword
Stormwater management is witnessing a growth in creative approaches. Stormwater managers across the
country are incorporating Stormwater treatment into landscapes and streetscapes. Stormwater is being captured
and reused for a variety of beneficial uses. Stormwater treatment is being incorporated from the rooftop to
the conveyance system to the stream edge. Stormwater is being integrated with land use plans to enhance
community benefits and water quality. A variety of professionals—engineers, landscape architects, community
planners, hydrologists, and public works staff (to name a few)—are now engaged in the challenge of managing
Stormwater in innovative ways.
At the same time, many communities are trying to build adequate programs to meet regulatory and community
demands. Stormwater managers are trying to tackle complex issues with limited budgets and staffing.
In putting together the guide, we have polled local Stormwater managers from across the country and gleaned
important lessons and tips. It is our hope that this guide will provide Stormwater professionals with practical
guidance, insights, and tools to build effective programs.
The guide is accompanied by several downloadable "tools." The tools are designed to be used and modified by
local Stormwater managers to help with program implementation. The tools are described in more detail in Chap-
ter 1, and can also be downloaded from the Center for Watershed Protection at www.cwp.org/postconstruction.
A note on web links: We have provided numerous web links within the document to ease the task of finding relevant resources.
However, links tend to become unreliable through time, especially for references to individual documents (such as pdfs). If you find
a broken link, try to shorten the link to the relevant agency or department name to search for the documentor page. Also, contact
center@cwp.org to report broken links.
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Contents
Post-Construction Stormwater Management Glossary:
Towards a Common Language ix
Chapter 1 Introduction and Background 1-1
1.1. Introduction 1-2
1.2. Relationship of Post-Construction to Construction Stormwater (Erosion and Sediment Control) 1-5
1.3. Relationship of Post-Construction to Impaired Waters (TMDLs) 1-6
1.4. Relationship of Post-Construction to Combined Sewer Overflows (CSOs) 1-8
1.5. Relationship of Post-Construction to Stormwater Retrofitting 1-8
1.6. Regulatory Background for Post-Construction Stormwater 1-10
1.7. Current Trends and Recommendations for Post-Construction Stormwater Management 1-10
Chapter 2 Post-Construction Program Development—Assessing Your Program 2-1
2.1. Assessing the Watershed and Community 2-2
2.2. Conducting a Post-Construction Program Self-Assessment 2-4
2.3. Post-Construction Program Planning 2-5
2.4. Stormwater Program Funding Options 2-9
Chapter 3 Land Use Planning as the First BMP: Linking Stormwater to Land Use 3-1
3.1. Introduction 3-2
3.2. Why Should Stormwater Managers Engage in Land Use Decisions? 3-2
3.3. Planning at Different Scales 3-3
3.4. A Process for Integrating Stormwater and Land Use 3-7
3.5. Step 1: Understand the Role of Impervious Cover and Other Watershed Factors at the Regional,
District/Neighborhood, and Site Scale 3-7
3.6. Step 2: Examine and Evaluate Land Use Codes for Drivers of Excess Impervious Cover and Land Disturbance 3-9
3.7. Step 3: Develop Relationships Between Stormwater Managers, Land Use Planners, and Other Officials 3-11
3.8. Step 4: Use Watersheds as Organizing Units for the Linked Stormwater/Land Use Program 3-13
3.9. Considering Climate Change in the Stormwater and Land Use Program 3-16
3.10. Relating Stormwater and Land Use to This Guidance Manual 3-16
Chapter 4 Developing a Stormwater Management Approach and Criteria 4-1
4.1. Clarifying the Stormwater Management Approach 4-2
4.2. A Recommended Stormwater Management Approach 4-2
4.3. Developing Stormwater Management Criteria 4-7
4.4. Developing a Rainfall Frequency Spectrum 4-11
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4.5. Special Stormwater Criteria for Sensitive Receiving Waters 4-11
4.6. A Watershed-Based Stormwater Approach 4-11
4.7. Detailed Stormwater Management Criteria Tables 4-15
Chapter 5 Developing a Post-Construction Stormwater Ordinance 5-1
5.1. Framework for the Stormwater Ordinance 5-2
5.2. Getting Started: Scoping Out the Right Ordinance for the Community 5-4
5.3. The Anatomyof a Stormwater Ordinance 5-5
5.4. Tips and Milestones for Building the Stormwater Ordinance 5-12
5.5. Involving the Public in Ordinance Development and Adoption 5-12
Chapter 6 Developing Stormwater Guidance Manuals 6-1
6.1. Introduction 6-2
6.2. Stormwater Guidance Manuals: An Overview 6-2
6.3. General Status and Trends 6-2
6.4. Getting Started: Scoping Out the Development of Stormwater Guidance Manuals 6-3
6.5. Outlining the Policy and Procedures Manual 6-4
6.6. Outlining the Stormwater Design Manual 6-5
6.7. Design Manual: List of Recommended BMPs 6-8
6.8. Design Manual: Stormwater BMP Design Specifications 6-8
6.9. Design Manual: Stormwater BMP Computations and Models 6-9
6.10. Design Manual: Leveling the Playing Field between Low-Impact Development (LID) and Conventional
Practices—Stormwater Credit Systems 6-15
6.11. Building a Stormwater Manual: The Manual Builder Tool 6-17
6.12. Tips for Stormwater Guidance Manual Project Management 6-22
6.13. Involving the Public in Developing the Stormwater Guidance Manual 6-22
Chapter 7 The Stormwater Plan Review Process 7-1
7.1. Introduction 7-2
7.2. Current Trends and Issues with Stormwater Plan Review 7-2
7.3. Getting Started: Scoping the Stormwater Plan Review Program 7-3
7.4. The Anatomyof Stormwater Plan Review 7-3
7.5. Tips for Building an Effective Stormwater Plan Review Process 7-7
7.6. Involving the Public in Stormwater Plan Review 7-13
Chapter 8 Inspection of Permanent Stormwater BMPs During Construction 8-1
8.1. Introduction 8-2
8.2. General Status, Trends, and Issues with Inspection of Permanent Stormwater BMPs During Construction 8-2
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8.3. Getting Started: Scoping Out a Program to Inspect Stormwater BMPs During Construction 8-2
8.4. The Anatomy of a Program to Inspect Stormwater BMPs During Construction 8-4
8.5. Tips for Developing an Effective Program to Inspect Stormwater BMPs During Installation 8-4
8.6. Involving the Public in Stormwater BMP Inspections 8-14
Chapter 9 Developing a Maintenance Program 9-1
9.1. Introduction 9-2
9.2. Current Status and Trends in Stormwater Maintenance 9-2
9.3. Getting Started—Scoping Out the Maintenance Program 9-2
9.4. Three Maintenance Approaches 9-5
9.5. Tips for an Effective Maintenance Program—From the Drafting Board to the Field 9-14
9.6. Public Involvement in the Maintenance Program 9-21
Chapter 10 Tracking, Monitoring, and Evaluation 10-1
10.1. Introduction and Overview 10-2
10.2. Current Status and Trends in Tracking, Monitoring, and Evaluation 10-2
10.3. A Framework for Post-Construction Tracking, Monitoring, and Evaluation 10-2
10.4. Establishing Measurable Goals 10-2
10.5. Selecting and Tracking Indicators of Success 10-4
10.6. Program Indicator Tracking 10-6
10.7. Stormwater Infrastructure Tracking 10-10
10.8. Land Use/Land Cover Tracking 10-11
10.9. Water Quality Monitoring and Modeling Tracking 10-11
10.10. Annual Reporting and Program Inspections & Audits 10-14
References
The following electronic tools are available at www.cwp.org/postconstruction:
Tool 1 - Post-Construction Stormwater Program Self-assessment
Tool 2 - Program and Budget Planning Tool
Tool 3 - Post-Construction Stormwater Model Ordinance
Tool 4 - Codes and Ordinances Worksheet
Tool 5 - Manual Builder
Tool 6-Checklists
Tool 7 - Performance Bond Tool
Tool 8 - BMP Evaluation Tool
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Contents
Tables
Table 1.1. Summary of Development Impacts on Water Resources 1-2
Table 1.2. Contents of Post-Construction Guidance Manual 1-3
Table 1.3. Coordination Between Construction and Post-Construction Stormwater 1-6
Table 1.4. Integrating Stormwater Retrofitting with the Six Minimum Measures 1-9
Table 1.5. EPA Stormwater Phase II Minimum Measure for Post-Construction Stormwater Management in New
Development and Redevelopment (40CFR122.34(b)(5)) 1-11
Table 1.6. Other Regulatory Drivers That Influence Post-Construction Stormwater 1-12
Table 1.7. Current Trends and Recommended Actions for Post-Construction Program 1-14
Table 2.1. Phase 1 of a Comprehensive Program Plan 2-6
Table 2.2. Phase 2 of a Comprehensive Program Plan 2-7
Table 2.3. Phase 3 of a Comprehensive Program Plan 2-8
Table 3.1. Common Land Use Development Regulations, Codes, and Policies That Can Drive Impervious Cover 3-3
Table 3.2. EPA Publications Related to Water Resources and Stormwater 3-6
Table 3.3. EPA's National Menu of Stormwater Best Management Practices: Selected Post-Construction BMPs Consistent
with Smart Growth and Site Design Strategies 3-7
Table 3.4. Key Local Documents to Reviewfor Consistency with Stormwater Goals 3-9
Table 3.5. Tips for Building Relationships Between Stormwater Managers, Land Use Planners, and Other Local Officials — 3-12
Table 3.6. Regulatory and Site Design/Policy Strategies to Integrate Stormwater, Land Use, and Watersheds 3-13
Table 3.7. Integrated Stormwater and Land Use Strategies Based on WATERSHED CHARACTERISTICS 3-15
Table 3.8. Integrated Stormwater and Land Use Strategies Based on LAND USE CHARACTERISTICS 3-15
Table 3.9. Climate Change and Conceptual Land Use/Stormwater Adaptations 3-17
Table 4.1. Critical Decisions to Identify a Stormwater Management Approach 4-3
Table 4.2. Hierarchy of Stormwater BMP Selection—Site Planning and Design 4-4
Table 4.3. Hierarchy of Stormwater BMP Selection—Source Control Practices 4-5
Table 4.4. Hierarchy of Stormwater BMP Selection—Stormwater Collection and Treatment 4-6
Table 4.5. Suggested Adaptations for Stormwater Management Criteria in Different Settings 4-9
Table 4.6. Rainfall Statistics and Frequency Spectrum Data for Select U.S. Cities 4-13
Table 4.7. Stormwater Criteria for Ordinances and Design Guidance: Natural Resources Inventory 4-16
Table 4.8. Stormwater Criteria for Ordinances and Design Guidance: Runoff Reduction 4-17
Table 4.9. Stormwater Criteria for Ordinances and Design Guidance: Water Quality Volume 4-18
Table 4.10. Stormwater Criteria for Ordinances and Design Guidance: Channel Protection 4-19
Table 4.11. Stormwater Criteria for Ordinances and Design Guidance: Flood Control 4-21
Table 4.12. Stormwater Criteria for Ordinances and Design Guidance: Redevelopment 4-22
Table 4.13. Special Stormwater Criteria for Lakes and Water Supply Reservoirs 4-23
Table 4.14. Special Stormwater Criteria for Trout and Salmon Streams 4-24
Table 4.15. Special Stormwater Criteria for Groundwater 4-25
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Table 4.16. Special Stormwater Criteria for Wetlands 4-26
Table 4.17. Special Stormwater Criteria for Impaired (TMDL-Listed) Waters 4-27
Table 5.1. Basic Elements of a Stormwater Ordinance 5-5
Table 5.2. Purposes Section of a Stormwater Ordinance 5-6
Table 5.3. Examples of Stormwater Ordinance Applicability Criteria in Use Around the Country 5-7
Table 5.4. Common Exemptions in Stormwater Ordinances 5-8
Table 5.5. Plan Submission and Review Elements in a Stormwater Ordinance 5-10
Table 5.6. Types of Penalties and Remedies 5-11
Table 5.7. Tips and Milestones for Building the Stormwater Ordinance 5-13
Table 5.8. Public Participation Techniques for Ordinance Development 5-14
Table 6.1. Typical Policy and Procedures Manual Outline 6-5
Table 6.2. Policy and Procedures Manual Content 6-6
Table 6.3. Typical Design Manual Outline 6-7
Table 6.4. Developing a Recommended BMP List 6-9
Table 6.5. Examples of Maintenance Reduction Criteria 6-10
Table 6.6. Examples of Typical Modeling and Design Assumptions 6-11
Table 6.7. Summary of Hydrologic and Hydraulic Models 6-12
Table 6.8. Description and Applications for Various Models 6-13
Table 6.9. Runoff Reduction for Various BMPs 6-16
Table 6.10. Eligibility Criteria for Grass Channel Credit 6-17
Table 6.11. Manual Writing Do's and Don'ts 6-18
Table 6.12. Directory of State and Local Stormwater Manuals Reviewed 6-19
Table 6.13. Summary of the Manual Building Tool 6-21
Table 6.14. Projected Staff Effort for Each Step of the Manual-Writing Cycle 6-23
Table 6.15. Pros and Cons of Using In-House and Consultant Labor to Build a Stormwater Management Guidance Manual—6-24
Table 6.16. Getting the Most from a Manual Consultant 6-24
Table 6.17. Key Local Stakeholders to Involve in the Manual-Building Process 6-25
Table 6.18. Tips for Making the Most of the Stakeholder Input Process 6-26
Table 6.19. Tips for Effective Manual Training 6-26
Table 7.1. Brief Description of Tasks in Stormwater Review Flowchart 7-5
Table 7.2. Typical Local, State, and Federal Plans and Permits that Should Be Coordinated with Review of Stormwater Plans... .7-7
Table 7.3. Documentation for Transferring Project to Inspections and Maintenance 7-7
Table 7.4. Important Policy Questions for Stormwater Plan Review 7-8
Table 7.5. Trade-offs in Having Consultants Review Plans 7-8
Table 7.6. Plan Review Checklists Provided in Stormwater Checklist Tool 7-9
Table 7.7. Recommended Computation Submittal Package 7-11
Table 7.8. Key Stakeholders in Stormwater Development Review and Selected Strategies 7-14
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Table 8.1. Brief Description of Tasks in Construction Inspection Process Flowchart 8-6
Table 8.2. Pros and Cons of Using Different Inspection Options 8-8
Table 8.3. BMP Construction Checklists Provided in Tool 6: Checklists 8-10
Table 8.4. Methods to Integrate Construction Inspections and Plan Review 8-13
Table 8.5. Key Stakeholders in Post-Construction BMP Inspection and Selected Strategies 8-15
Table 9.1. Common Maintenance Pitfalls 9-3
Table 9.2. Maintenance Program Service Matrix 9-4
Table 9.3. Examples of Structural and Routine Maintenance 9-5
Table 9.4. Three Maintenance Program Approaches 9-6
Table 9.5. Legal and Administrative Foundation for a Maintenance Program 9-7
Table 9.6. Review of Available Compliance Methods 9-9
Table 9.7. BMP Inventory Checklist 9-10
Table 9.8. Considerations for Stormwater Easements 9-11
Table 9.9. Tracking Items for a Municipally Operated Maintenance Program 9-13
Table 9.10. Methods to Assign and Communicate Maintenance Responsibilities 9-14
Table 9.11. Key Maintenance Considerations for Various BMPs 9-18
Table 9.12. Key Stakeholders in Stormwater Maintenance & Selected Strategies 9-22
Table 10.1. Examples of Measurable Goals for Post-Construction Practices: Keyed to Chapters of this Guide 10-5
Table 10.2. Indicators of Post-Construction Stormwater Program Success 10-7
Table 10.3. Monitoring and Modeling Resources for Municipal Stormwater Programs 10-13
Table 10.4. Preparing for an MS4 Audit by a Regulatory Agency 10-16
Figures
Figure 1.1. Urban development increases runoff volume, peak discharge, and time to peak 1-2
Figure 1.2. The Post-Construction Stormwater Life-Cycle, as presented in this guide 1-5
Figure 1.3. Construction Stormwater and post-construction Stormwater plans must be coordinated to protect
post-construction design features and BMPs 1-7
Figure 2.1. Example maps for post-construction program development 2-2
Figure 2.2. Impervious cover by watershed 2-3
Figure 2.3. Examples of mapping of water resources information from Augusta County, Virginia 2-4
Figure 3.1. Watershed impervious cover at different development densities 3-4
Figure 3.2. Conceptual model illustrating the relationship between impervious cover and stream health 3-8
Figure 4.1. Graphic representation of the nested approach to Stormwater management criteria 4-8
Figure 4.2. Creating a Rainfall Frequency Spectrum (RFS) to assist with development of Stormwater
management criteria 4-12
Figure 4.3. Examples of projects for a in a watershed-based Stormwater management program 4-14
Figure 5.1. Example of conflicts with existing codes 5-3
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Contents
Figure 5.2. Tool 3: Model Post-Construction Stormwater Ordinance 5-4
Figure 7.1. Typical stormwater plan review process 7-4
Figure 7.2. Tool 6: Example plan review checklists 7-10
Figure 7.3. Pre-submittal meeting to review stormwater alternatives 7-11
Figure 7.4. Training for plan reviewers and design consultants 7-12
Figure 7.5. Example of Web-based plan review tracking system from the City of Greensboro, North Carolina 7-13
Figure 8.1. Common issues with installation of post-construction BMPs, using bioretention as an example 8-3
Figure 8.2. Typical process for conducting inspections of post-construction BMPs during construction 8-5
Figure 8.3. Tool 6: Example construction/installation checklists for structural and nonstructural BMPs 8-11
Figure 8.4. Construction inspectors and as-built plans 8-12
Figure 8.5. Co-inspections by construction inspectors and plan reviewers 8-13
Figure 9.1. BMP tracking systems 9-8
Figure 9.2. Inspector training 9-12
Figure9.3. Performing maintenance tasks 9-13
Figure 9.4. Examples of Poor and Good Maintenance Features Related to the Design Process 9-15
Figure 10.1. Post-construction tracking, monitoring, and evaluation framework 10-3
Figure 10.2. Inlet cleaning data derived from maintenance records 10-8
Figure 10.3. The City of San Diego's plan review process tracking form 10-9
Figure 10.4. Global positioning systems (GPS) linked with geographic information systems (GIS) 10-10
Figure 10.5. Examples of how stormwater activities can be reported 10-15
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Managing Stormwater in Your Community
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Post-Construction Stormwater
Management Glossary:
Towards a Common Language
As stormwater management has evolved, so has the
language used to describe certain practices and tech-
niques. At this point, the terminology of stormwater
can be confusing—largely because multiple terms are
used to describe similar and overlapping concepts. Are
we building stormwater BMPs, stormwater treatment
practices, or structural measures? Is our innovative
design approach known as low-impact development,
better site design, environmental site design, non-
structural measures, or green infrastructure?
This guide uses certain terminology, and it is impor-
tant to understand the meaning of these terms as it
relates to the material within the guidance. This is not
an attempt to be definitive with regard to the termi-
nology, as it is certain to evolve over time. Also, the list
below is not exhaustive, as a much fuller list of terms
can be found in most stormwater ordinances, regula-
tions, and manuals, including the Post-Construction
Model Ordinance provided in Tool 3
(wwiv.civp.org/posfconsfrucf/on).
Combined Sewer Overflow (CSO)
Combined sewer systems are sewer systems that
collect both stormwater runoff and sanitary sew-
age in the same pipe to be carried to a wastewater
treatment plant. Wet weather events can sometimes
cause these combined sewer systems to exceed their
hydraulic capacity and result in a combined sewer
overflow (CSO). A CSO can result in untreated human
and industrial waste, toxic materials and debris being
discharged to nearby streams, rivers, lakes or estuar-
ies, impacting water quality and aquatic habitat. CSOs
can cause beach closings, shellfishing restrictions and
other water body impairments.
Environmental Site Design (ESD)
Environmental Site Design (ESD) is an effort to mimic
natural systems along the whole stormwater flow path
through combined application of a series of design
principles throughout the development site. The
objective is to replicate forest or natural hydrology
and water quality. ESD practices are considered at
the earliest stages of design, implemented during
construction and sustained in the future as a low
maintenance natural system. Each ESD practice
incrementally reduces the volume of stormwater on
its way to the stream, thereby reducing the amount
of conventional stormwater infrastructure required.
Example practices include preserving natural areas,
minimizing and disconnecting impervious cover,
minimizing land disturbance, conservation (or cluster)
design, using vegetated channels and areas to treat
stormwater, and incorporating transit, shared parking,
and bicycle facilities to allow lower parking ratios.
The Center for Watershed Protection has published
information on this concept using the term "Better Site
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Post-Construction Stormwater Management Glossary: Towards a Common Language
Design." For more information, see: Better Site Design:
A Handbook for Changing Development Rules in Your
Community, Center for Watershed Protection, Inc.
wwiv.civp.org > Online Store > Better Site Design.
Green Infrastructure
Green infrastructure refers to natural systems that
capture, cleanse and reduce stormwater runoff using
plants, soils and microbes. On the regional scale,
green infrastructure consists of the interconnected
network of open spaces and natural areas (such as
forested areas, floodplains and wetlands) that improve
water quality while providing recreational opportuni-
ties, wildlife habitat, air quality and urban heat island
benefits, and other community benefits. At the site
scale, green infrastructure consists of site-specific
management practices (such as interconnected natural
areas) that are designed to maintain natural hydrologic
functions by absorbing and infiltrating precipitation
where it falls.
Additional information on green infrastructure is
available from EPA at www.epa.gov/npofes/
greeninfrastructure.
Low-Impact Development (LID)
Low-Impact Development (LID) is a stormwater man-
agement approach that seeks to manage runoff using
distributed and decentralized micro-scale controls.
LID's goal is to mimic a site's predevelopment hydrol-
ogy by using design techniques that infiltrate, filter,
store, evaporate, and detain runoff close to its source.
Instead of conveying and treating stormwater solely
in large end-of-pipe facilities located at the bottom
of drainage areas, LID addresses stormwater through
small-scale landscape practices and design approaches
that preserve natural drainage features and patterns.
Several elements of LID—such as preserving natural
drainage and landscape features—fit right into the
Green Infrastructure approach. Additional information
on LID is available at http://www.epa.gov/
owow/nps///d.
Municipal Separate Storm Sewer System (MS4)
A Municipal Separate Storm Sewer System (MS4) is a
publicly owned conveyance or system of conveyances
that discharges to waters of the United States or waters
of the state, and is designed or used for collecting or
conveying stormwater. Conveyances can include any
pipe; ditch or gully; or system of pipes, ditches, or
gullies, that is owned or operated by a governmental
entity and used for collecting and conveying storm-
water. Discharges from MS4s are regulated under the
NPDES municipal stormwater program (Phase I and
Phase II).
Non-Structural BMP
Non-structural BMPs are used in lieu of or to supple-
ment structural BMPs. Non-structural measures may
include minimization and/or disconnection of imper-
vious surfaces; development design that reduces the
rate and volume of runoff; restoration or enhancement
of natural areas such as riparian areas, wetlands, and
forests; and vegetated areas that intercept roof and
driveway runoff. In this regard, "non-structural BMP"
is a generic term for many of the techniques under
the umbrellas of Green Infrastructure and Low-Impact
Development. Non-structural BMPs can also refer to
program elements aimed at changing behaviors that
lead to polluted runoff. Examples include storm drain
stenciling, outreach programs, and yard fertilizer edu-
cation programs.
Post-Construction Stormwater
This terminology is used to distinguish stormwater
practices used during site construction (otherwise
known as "construction stormwater" or "erosion and
sediment control") from those that are used on a
permanent basis to control runoff once construction is
complete ("post-construction stormwater"). Construc-
tion stormwater is minimum measure #4 in the Phase II
municipal stormwater permit program, and post-con-
struction stormwater is minimum measure #5.
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Post-Construction Stormwater Management Glossary: Towards a Common Language
Smart Growth
Smart Growth refers to coordinated planning to sup-
port economic, community and environmental goals.
Smart Growth focuses on planning where develop-
ment is located in relationship to urban infrastructure
and environmental features, and is a big-picture way
to manage the overall footprint of impervious surfaces
at the neighborhood, watershed, and community
scales. Smart Growth encourages infill and redevel-
opment within designated areas as a way to keep
the development footprint from expanding across
important rural and natural resources areas. Smart
Growth also encourages the coordination of utility
plans, transportation plans, economic development
plans, stormwater codes, design guidelines, and other
policies to achieve the best outcomes for the economy
and environment. For more information visit:
http://www.epa.gov/smartgrowth/
Stormwater BMP
BMP refers to "best management practice." It is a
generic term that has been used interchangeably with
stormwater practice or stormwater treatment prac-
tice. Stormwater BMPs can be either "structural" or
"non-structural."
Total maximum daily load (TMDL)
A Total Maximum Daily Load (TMDL) is a calculation of
the maximum amount of a pollutant that a waterbody
can receive and still meet water quality standards, and
an allocation of that amount to the pollutant's sources.
A TMDL is the sum of the allowable loads of a single
pollutant from all contributing point and nonpoint
sources. The calculation must include a margin of
safety to ensure that the waterbody can be used for
the purposes the State has designated. The calculation
must also account for seasonal variation in water
quality.
Watershed Management
A watershed is the land area from which water drains
into a stream, channel, lake, reservoir, or other body
of water. Many communities are using the watershed
management framework to address the intersection of
land development and water quality/quantity. Water-
shed management often involves multi-jurisdictional
collaboration to identify and address cross-boundary
water quality problems and flooding.
Structural BMP
Structural BMPs generally require construction sup-
ported by engineering plans, and become permanent
features of the landscape. Examples include ponds,
wetlands, underground or surface chambers or filters,
bioretention areas, swales, and infiltration trenches.
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Managing Stormwater in Your Community
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Chapter 1
Introduction and
Background
Chapter 1
Introduction &
Background
Chapter 10
Tracking, Monitoring
& Evaluation
Chapters
Maintenance
Program
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 2
Program
Development
Chapter 7
Plan Review
Process
Chapter 3
Linking Stormwater to
Land Use
Chapter 4
Stormwater Approach
& Criteria
Chapter 5
Post-Construction
Ordinance
Chapters
Stormwater Guidance
Manual
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
Post-Construction Stormwater Basics and the
Guidance Manual
Relationship of Post-Construction Stormwater
Management to:
Construction Stormwater Management
Impaired Waters (TMDLs)
Combined Sewer Overflows
9 Stormwater Retrofitting
Regulatory Background
Current Trends and Recommendations for Post-
Construction Stormwater Management
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Chapter 1: Introduction and Background
1.1. Introduction
Communities across the country are increasingly view-
ing stormwater management as an opportunity to
improve the environment, create attractive public and
private spaces, engage the community in environmen-
tal stewardship, and remedy the ills of the past, when
development took place with inadequate stormwater
controls.
While stormwater management has enjoyed a higher
profile in recent times, communities across the country
are striving to build the programmatic capabilities to
effectively manage stormwater and meet regulatory
requirements, such as Phases I and II of the National
Pollutant Discharge Elimination System (NPDES)
municipal stormwater permit program.
Many local programs have a strong emphasis on the
stormwater basics of providing flood control and
adequate drainage. Recently, many stormwater pro-
grams have become more sophisticated and "greener"
by incorporating channel protection, groundwater
recharge, protection of sensitive receiving waters,
control of the overall volume of stormwater runoff, and
use of natural systems and site design techniques to
control runoff.
Water quality impacts from urban runoff can be signifi-
cant. Many streams, lakes, and estuaries in urban areas
are impaired due to urban runoff (http://iaspub.epa.gov/
watersW/attains_nation_cy.control). Impervious
surfaces, disturbed soils, and managed turf associated
with urban development can have multiple impacts on
water quality and aquatic life. These impacts are sum-
marized in Table 1.1.
Urban development can also impact the post-develop-
ment hydrograph discharging to urban streams
(Figure 1.1). Compared to the pre-development condi-
tion, post-development stormwater discharges can
increase the runoff volume, increase the peak discharge,
and decrease the infiltration of stormwater, which
thereby decreases baseflow in headwater streams.
These changes to stream hydrology result in negative
impacts on channel stability and the health of aquatic
biological communities. Common problems include
Table 1.1. Summary of Development Impacts on
Water Resources
Increases in:
Impervious cover,
compacted soils, managed
turf, and other land covers
that contribute pollutants
Stormwater volume
Stormwater velocity
Pollutant loads
Stream channel erosion
Decreases in:
Health and safety of
receiving waters
Groundwater recharge
Stream channel stability
Health, safety, and integrity
of water supplies, reservoirs,
streams, and biological
communities
Stream habitat
Large
Storm
Higher and More Rapid
More Runoff Volume
^^^^^^ Pre-developmet
— — — — • Post-development
Figure 1.1. Urban development increases runoff
volume, peak discharge, and time to peak
bank scouring and erosion, increased downstream
flooding, and loss of in-stream habitat for macroinverte-
brates, fish, and other organisms.
Purpose and Audience for this Guide
This guide is intended for Phase II NPDES Municipal
Separate Storm Sewer System (MS4) communities
(which are required to establish a post-construction
program), as well as other smaller unpermitted
MS4s that are interested in protecting local water
resources. Other entities responsible for implementing
post construction controls, such as military bases,
transportation departments, and school districts, will
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Chapter 1: Introduction and Background
also find this guide useful. Stormwater Phase I and other
communities already implementing a post-construction
program could benefit from the program assessment
described in Section 2.2 and other sections of the guide
to help them identify key areas for improvement.
Finally, this guide is intended for multiple audiences
within a local government. The guide recognizes the
important link between overall comprehensive land
use planning and the more technical components of
a stormwater program. Often, land use planners and
stormwater managers do not collaborate on large-
scale land use and development issues. However, the
activities of both groups have a profound impact on
the health of watersheds and receiving waters. The
guide, and especially Chapter 3, is meant to bridge this
gap and promote a stronger link.
What's in the Guide
The guide contains chapters that address key elements
of a post-construction program, and also several
companion "tools." The tools are designed to be
downloaded and adapted by local programs to help
build program capabilities. The chapters and tools in
the guide are listed in Table 1.2. Figure 1.2 portrays
the chapters of the guide in graphical format, showing
the cyclical or iterative nature of the various program
elements.
Table 1.2. Contents of Post-Construction Guidance Manual
Chapters
Description
Chapter 1
Introduction and Background
Introduces the contents of the guide and related tools. Provides a brief regulatory
background on post-construction stormwater management.
Chapter 2
Post-Construction Program
Development
Provides the stormwater manager with an understanding of the community and watershed
components of a stormwater plan and introduces a program self-assessment tool.
Companion to Tool 1: Self-Assessment and Tool 2: Program and Budget Planning Tool
Chapter 3
Land Use Planning as the First
BMP: Linking Stormwater to
Planning
Examines the link between stormwater and land use planning. Details how to build a more
effective program through integrated stormwater and planning tools.
Companion to Tool 4: Codes and Ordinance Worksheet
Chapter 4
Developing a Stormwater
Management Approach and
Criteria
Introduces a recommended stormwater management approach and how to distill this
approach into criteria for a stormwater ordinance and guidance manual.
Companion to Tool 5: Manual Builder
Chapter 5
Developing a Post-
Construction Stormwater
Ordinance
Works through the nuts and bolts of building a stormwater ordinance and illustrates major
decision points.
Companion to Tool 3: Model Ordinance
Chapter 6
Developing a Stormwater
Guidance Manual
Reviews stormwater policy and design guidance from A to Z. Includes tips for building a
manual that best suits the community.
Companion to Tool 5: Manual Builder
Chapter 7
The Stormwater Plan Review
Process
Delves into the anatomy of a good review process and how to use it to ensure good BMP
design and long-term maintenance.
Companion to Tool6: Checklists
Chapter 8
Inspection of Post-Construction
BMPs during Construction
Offers guidance on the process for initial installation of post-construction BMPs during the
construction phase.
Companion to Tool 6: Checklists and Tool 7: Performance Bonds
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Chapter 1: Introduction and Background
Table 1.2. Contents of Post-Construction Guidance Manual (continued)
Chapters
Chapter 9
Developing a Maintenance
Program
Chapter 10
Tracking, Monitoring, and
Evaluation
Tools
Tooll
Post-Construction Stormwater
Program Self-assessment
Tool 2
Program and Budget Planning
Tool
Tool 3
Post-Construction Stormwater
Model Ordinance
Tool 4
Codes and Ordinance
Worksheet
ToolS
Manual Builder
Tool 6
Checklists
Tool?
Performance Bond Tool
ToolS
BMP Evaluation Tool
Description
Explores three models for a maintenance program and provides tips for an effective program.
Companion to Tool 5: Manual Builder, Tool 6: Checklists and Tool 7: Performance Bonds
Reviews the development of measurable goals and milestones. Provides guidance on program
evaluation, annual reports, and preparing fora possible program audit.
Companion to Tool 8: BMP Evaluation Tool
Description
Evaluates the current status of the program, and where it needs to go. This checklist tool can
be used to set short- and long-term goals.
Provides planning milestones and assists with development of planning-level budget figures
using a spreadsheet.
Provides model language to build or enhance the ordinance. Language is keyed to three
levels of program sophistication.
Assesses zoning, subdivision, and other codes in the context of impervious cover creation and
ability to promote effective Stormwater management through design.
Provides links to the best design and program resources around the country. Useful for
Stormwater managers who are developing a manual or adapting an existing manual.
Provides detailed checklists for plan review, best management practice (BMP) installation
during construction, and maintenance. The checklists address both structural and
nonstructural Stormwater BMPs.
Supplies templates that can be adapted to develop a performance bond for the program — an
effective tool to ensure good BMP installation.
Asks the right questions when it comes to verifying the performance of various BMPs,
especially proprietary devices.
Download Tools at: www.cwp.org/posfconsfrucf/on
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Chapter 1: Introduction and Background
Chapter 2
Program
Development
Chapter 3
Linking Stormwater to
Land Use
Chapter 9
Maintenance
Program
Post-Construction
Life Cycle
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 6
Stormwater Guidance
Manual
Figure 1.2. The Post-Construction Stormwater Life-Cycle, as presented in this guide. The program
elements are presented in a cyclical or iterative format, as programs evolve.
1.2. Relationship of Post-Construction to
Construction Stormwater (Erosion and
Sediment Control)
This guide addresses runoff from projects after the
construction phase is complete. Stormwater runoff
from projects during active construction is typically
addressed through requirements for Stormwater
pollution prevention plans (SWPPPs) and erosion and
sediment control BMPs. Guidance on developing
SWPPPs for construction projects is available from EPA
(see Developing Your Stormwater Pollution Prevention
Plan: A Guide for Construction Sites at
http://www.epa.gov/npdes/swpppguide).
A local program must carefully consider the
relationship between construction and post-
construction Stormwater. Construction Stormwater
BMPs listed in a SWPPP are designed to minimize
impacts during the active construction phase, and
they do not always translate into BMPs applicable for
post-construction. Post-construction BMPs must treat
runoff from the newly constructed or redeveloped
site, including runoff from roads, parking lots,
yards, rooftops, and other land uses associated with
development.
In some cases, construction and post-construction
BMPs can be located in the same area, such as
a sediment control basin or trap converted to a
permanent Stormwater BMP. Colocating construction
and post-construction BMPs can help a designer follow
natural drainage patterns, can be an economical
approach, and often works when proper construction
sequencing and standards are followed (see Table 1.3
for more details).
However, increasingly, it is being found that
construction and post-construction BMPs should
be located on different parts of the site and have
different sizing and design criteria. For instance,
post-construction BMPs might involve practices
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Chapter 1: Introduction and Background
distributed across the site, such as bioretention and
infiltration practices. In this case, the post-construction
BMP locations must be carefully protected during
the construction phase in order to preserve the soil
structure necessary for long-term BMP effectiveness.
Also, the post-construction BMPs must be installed in
the proper construction sequence—after contributing
drainage areas are stabilized—in order to prevent
construction sediment runoff from clogging the
newly installed bioretention or infiltration practices.
Figure 1.3 portrays typical coordination needs
between construction and post-construction
stormwater planning.
Table 1.3 notes several other dos and don'ts with
regard to coordinating construction and post-
construction BMPs.
1.3. Relationship of Post-Construction to
Impaired Waters (TMDLs)
Under the authority of section 303(d) of the Clean
Water Act, waterbodies that do not meet water qual-
ity standards are considered "impaired" and a "Total
Maximum Daily Load" (TMDL) study must be con-
ducted. This study computes the pollutant load that
a waterbody can receive and still meet water quality
standards, and it allocates this load to various point
and nonpoint sources. Authorized states and tribes
administer the TMDL program.
Currently, thousands of impaired waters are listed
on state 303(d) lists. The most common sources of
impairment associated with stormwater include sedi-
ment, pathogens (bacteria), nutrients, and metals
(USEPA, 2007). Stormwater and urban and suburban
runoff are significant contributors to impairments
nationwide and the leading cause of impairments
within some regions (USEPA Region 5,2007). For this
reason, EPA and relevant state agencies are increas-
ingly motivated to create a stronger link between
TMDLs and stormwater permits, such as MS4, con-
struction site, and industrial permits. Future rounds of
MS4 permit coverage will seek more targeted and/or
stringent stormwater controls for impaired watersheds
within the jurisdiction of MS4s.
Table 1.3. Coordination Between Construction and
Post-Construction Stormwater
DO:
>• Coordinate plan review for construction and post-
construction BMPs.
Make sure the Limits of Disturbance (LODs) for the
SWPPP (construction stormwater plan) are coordinated
with natural areas and open-space areas that are
supposed to be protected per the post-construction
plan.
>• Make sure that areas designated for post-construction
BMPs are protected from disturbance and compaction
during construction and are noted in the SWPPP. This is
especially true for infiltration and bioretention practices
that depend on an undisturbed soil structure.
Colocate construction and post-construction BMPs
where it makes sense and won't compromise the
integrity of post-construction BMPs. Good candidates
forcolocation include:
- Basins that will be converted from construction
to post-construction configurations by dredging
construction sediments and modifying outlet
structures
- Sediment traps that will be converted to
bioretention/filtration (or another BMP) when, after
drainage areas are stabilized, construction sediments
are removed and the basin floor is excavated to a
deeper layer (below the original sediment trap invert)
with good soils for infiltration
- Other cases where the local program staff can ensure
the integrity of the post-construction BMPs
- Care should especially be taken with infiltration
facilities to avoid conflicts between construction and
post-construction BMPs and compaction of soils.
>• Make sure that inspectors and contractors are aware of
both construction and post-construction BMPs to be
installed at a site.
DON'T:
Approve a SWPPP that conflicts with a post-construction
stormwater plan in terms of protection of natural areas,
tree protection, limits of disturbance, etc.
Colocate construction and post-construction BMPs
where soil compaction and sedimentation will damage
the integrity of the post-construction BMP.
Suspend inspections or release performance bonds
until the post-constructions BMPs have been installed
correctly.
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Chapter 1: Introduction and Background
— — — — Riparian buffer/natural area boundary
Colocated construction-phase sediment basin and
post-construction BMP.
Post-construction bioretention/infiltration area — Soil must be
protected during construction. Do not use for construction-phase
BMPs unless specific conditions are met (Table 13).
, Limits of Disturbance (LOD) for construction-phase SWPPP — Must
protect riparian buffer and post-construction infiltration area.
Fencing recommended.
Figure 1.3. Construction stormwater and post-construction stormwater plans
must be coordinated to protect post-construction design features
and BMPs
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Chapter 1: Introduction and Background
For the local stormwater manager, this will require an
effort to tailor certain stormwater criteria and BMPs
to help meetTMDL pollutant-reduction benchmarks.
Chapter 4 (Table 4.17) provides more detail on creating
a stronger link between stormwater criteria and TMDLs.
1.4. Relationship of Post-Construction to
Combined Sewer Overflows (CSOs)
Many communities in the past built combined sewer
systems that collect both stormwater runoff and
sanitary sewage in the same pipe to be carried to a
wastewater treatment plant. Wet weather events can
sometimes cause these combined sewer systems to
exceed their hydraulic capacity, resulting in combined
sewer overflows (CSOs). A CSO can result in untreated
human and industrial waste, toxic materials, and debris
being discharged to receiving waterbodies, impacting
water quality and aquatic habitat. CSOs cause beach
closings, shellfishing restrictions, and other waterbody
impairments. Combined sewer systems serve roughly
772 communities containing about 40 million people.
(See EPA's NPDES Web site, accessed November 2007:
wwiv.epa.gov/npofes/cso)
EPA's Combined Sewer Overflow Control Policy is the
national framework for the control of CSOs through
the NPDES permitting program (www.epa.gov/npdes/
pubs/owmOm.pdf). The Policy includes a set of Nine
Minimum Control Measures designed to address the
causes of CSOs and limit their occurrence:
1. Monitoring to effectively characterize impacts
from CSO discharges
2. Proper operation and maintenance programs
3. Maximum use of the collection system for storage
4. Review and modification of pretreatment
programs
5. Maximizing flows to the wastewater treatment
plant
6. Prohibiting dry weather CSO discharges
7. Control of solids and floatable materials
8. Pollution prevention programs
9. Public notification
Many of the measures required for CSO control can
be directly related to post-construction stormwater
management. For instance, the volume and frequency
of CSO events can be reduced by implementing
stormwater management practices that reduce the
volume and rates of runoff. Treatment of stormwater
runoff before it enters the combined sewer system also
reduces the level of pollutants potentially discharged
in an overflow event. Pollution prevention programs
focused on reducing the exposure of pollutants to
runoff entering a combined sewer system also help
eliminate excess nutrients and other pollutants.
1.5. Relationship of Post-Construction to
Stormwater Retrofitting
Stormwater retrofitting refers to a series of techniques
that help to restore watersheds by providing stormwa-
ter treatment in locations where practices previously
did not exist or were ineffective. Stormwater retrofits
are typically installed at older, existing stormwater
facilities, within the conveyance system, above or
below outfalls, at stormwater hotspots, and at other
locations that are close to the source of runoff. The
intent is to capture and treat stormwater runoff before it
is delivered to the receiving waters (Schueler et al. 2007).
Retrofitting spans the regulatory and non-regulatory
sides of post-construction stormwater management:
In a regulatory sense, the MS4 requirements
pertain to new development and redevelopment
projects. Redevelopment cases, in particular, are
places where retrofitting can play a major role.
For instance, existing stormwater facilities and/or
conveyance systems can be retrofitted to provide
better water quality treatment.
In the non-regulatory context, retrofitting is a
critical tool to help achieve watershed restoration
goals, especially in watersheds where much of
the development took place prior to modern
stormwater management. For these communities,
a retrofit program can be built into the overall
post-construction program to help fulfill MS4
commitments.
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Chapter 1: Introduction and Background
When tailored to a community's watershed needs,
retrofitting can help meet multiple objectives. For
instance, a retrofitting program can reduce runoff
volumes in combined sewer systems; help reduce the
amount of trash and floatables reaching waterbodies;
support downstream stream restoration projects; help
solve existing flooding, erosion, and water quality
problems; and provide key demonstration and out-
reach projects (Schueleret al. 2007).
Table 1.4 lists several ideas for how retrofitting can
be integrated with the six minimum measures in the
Phase II MS4 program.
To assist communities with a retrofitting program, the
Center for Watershed Protection has produced a com-
prehensive guidance manual on stormwater retrofitting:
Urban Stormwater Retrofit Practices, Version 10, Urban
Subwatershed Restoration Manual Series, Manual 3
(August 2007). wwiv.civp.org > Resources > Controlling
Runoff & Discharges > Stormwater Management >
National/Regional Guidance.
Table 1.4. Integrating Stormwater Retrofitting with the Six Minimum Measures
Minimum Measure
How Retrofitting Can Help
1. Public Education
and Outreach
Use high-visibility public sites for retrofit projects and include educational signage and
interpretation.
>• Use retrofit demonstration sites for outdoor classrooms, educational events, and field trips.
2. Public Participation
and Involvement
>• Get citizen advisory committees involved in establishing retrofit objectives and candidate
locations.
>• Use volunteer labor to help with retrofit project light construction, planting, mulching, and
maintenance.
3. Illicit Discharge
Detection and
Elimination
Use the retrofitfield reconnaissance process to lookfor illicit discharges.
4. Construction Site
Runoff Control
*• Use retrofit projects to demonstrate proper erosion and sediment control to the development
community.
Look for construction sites during the retrofitfield reconnaissance process.and conduct follow-up
inspections.
5. Post-Construction
Runoff Control
>• Establish retrofitting protocols for redevelopment sites.
>• In some cases, have a developer do an on-site or off-site retrofit to satisfy post-construction
requirements.
>• In some cases, collect a fee-in-lieu payment from a developer to help pay for strategic retrofits in
the watershed.
Build retrofitting into the facilities planning, capital improvements, and facilities maintenance
program.
6. Pollution
Prevention
and Good
Housekeeping
>• Include pollution prevention and landscape stewardship projects in the retrofit program. Start with
public sites, such as schools, parks, and public works yards, and incorporate findings into ongoing
maintenance activities.
Look for opportunities to retrofit water quality treatment at municipal stormwater hotspots, such
as vehicle maintenance, fueling, public works, and grounds maintenance facilities.
Use stormwater retrofit projects to set a good example for the development community and public.
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Chapter 1: Introduction and Background
1.6. Regulatory Background for Post-
Construction Stormwater
Both Phase I and Phase II of the NPDES stormwater
program require municipalities to develop and imple-
ment programs to address stormwater runoff from
areas of new development and redevelopment (i.e.,
post-construction runoff). The Phase I post-construc-
tion requirements are at 40 CFR Part 122.26(d). There
are approximately 1,000 Phase 1 permittees across the
country (U.S. GAO, 2007).
The stormwater Phase II post-construction require-
ments are at 40 CFR 122.34(b)(5) and listed in Table 1.5.
Because the Phase II regulations apply to smaller
communities, there are many more of them, currently
numbering over 5,000 nationally (U.S. GAO, 2007). Addi-
tionally, nontraditional MS4s in urbanized areas such
as military bases, public universities, and other govern-
mental facilities are also regulated under Phase II.
Authorized states and EPA regions use these Phase I and
Phase II regulations as the basis for developing permit
requirements for MS4s. The NPDES MS4 permits provide
more detailed requirements that MS4s must meet. In
response to these permit requirements, MS4s develop
detailed plans (often called Stormwater Management
Plans) that describe the activities and milestones that
the MS4 will meet over the five-year permit term.
Some states also have developed post-construction
standards and/or stormwater guidance manuals to
implement the stormwater regulations. Tool 5: Manual
Builder includes information on many state stormwa-
ter manuals and their associated Web sites.
The NPDES MS4 requirements are one of the various
federal, state, and local regulations and programs that
influence stormwater management and land develop-
ment practices. Table 1.6 lists other drivers that have
some connection to stormwater management. A local
program must understand this complex regulatory
environment to avoid conflicts and build a sustainable
program. Legal issues, such as court rulings involving
negligence and nuisance, can also drive the implemen-
tation of stormwater management at the local and
state levels.
1.7. Current Trends and Recommendations
for Post-Construction Stormwater
Management
The Center for Watershed Protection recently con-
ducted research that canvassed local government
stormwater professionals across the country (CWP,
2006). Respondents provided local information and
insights on a range of post-construction issues. Almost
100 different local governments across 30 states
responded, and the vast majority of respondents were
from Phase II communities.
Table 1.7 provides a summary of the current status
and trends in post-construction stormwater man-
agement based on this research. The table also lists
recommended actions and references the appropriate
chapters of this guide for more detailed information.
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Chapter 1: Introduction and Background
Table 1.5. EPA Stormwater Phase II Minimum Measure for Post-Construction Stormwater Management in New
Development and Redevelopment (40 CFR 122.34(b)(5))
(i) You must develop, implement, and enforce a program to address Stormwater runoff from new development and
redevelopment projects that disturb greater than or equal to one acre, including projects less than one acre that are part
of a larger common plan of development or sale, that discharge into your small MS4. Your program must ensure that
controls are in place that would preventer minimize water quality impacts.
(ii) You must:
(A) Develop and implement strategies which include a combination of structural and/or non-structural best
management practices (BMPs) appropriate for your community;
(B) Use an ordinance or other regulatory mechanism to address post-construction runoff from new development and
redevelopment projects to the extent allowable understate. Tribal or local law; and
(C) Ensure adequate long-term operation and maintenance of BMPs.
(iii) Guidance: If water quality impacts are considered from the beginning stages of a project, new development
and potentially redevelopment provide more opportunities for water quality protection. EPA recommends that the
BMPs chosen: be appropriate for the local community; minimize water quality impacts; and attempt to maintain pre-
development runoff conditions. In choosing appropriate BMPs, EPA encourages you to participate in locally-based
watershed planning efforts which attempt to involve a diverse group of stakeholders including interested citizens. When
developing a program that is consistent with this measure's intent, EPA recommends that you adopt a planning process
that identifies the municipality's program goals (e.g., minimize water quality impacts resulting from post-construction
runoff from new development and redevelopment), implementation strategies (e.g., adopt a combination of structural
and/or non-structural BMPs), operation and maintenance policies and procedures, and enforcement procedures. In
developing your program, you should consider assessing existing ordinances, policies, programs and studies that
address storm water runoff quality. In addition to assessing these existing documents and programs, you should provide
opportunities to the public to participate in the development of the program. Non-structural BMPs are preventative
actions that involve management and source controls such as: policies and ordinances that provide requirements and
standards to direct growth to identified areas, protect sensitive areas such as wetlands and riparian areas, maintain and/or
increase open space (including a dedicated funding source for open space acquisition), provide buffers along sensitive
water bodies, minimize impervious surfaces, and minimize disturbance of soils and vegetation; policies or ordinances that
encourage infill development in higher density urban areas, and areas with existing infrastructure; education programs for
developers and the public about project designs that minimize water quality impacts; and measures such as minimization
of percent impervious area after development and minimization of directly connected impervious areas. Structural
BMPs include: storage practices such as wet ponds and extended-detention outlet structures; filtration practices such as
grassed swales, sand filters and filter strips; and infiltration practices such as infiltration basins and infiltration trenches.
EPA recommends that you ensure the appropriate implementation of the structural BMPs by considering some or all
of the following: pre-construction review of BMP designs; inspections during construction to verify BMPs a re built as
designed; post-construction inspection and maintenance of BMPs; and penalty provisions for the noncompliance with
design, construction or operation and maintenance. Storm water technologies are constantly being improved, and
EPA recommends thatyour requirements be responsive to these changes, developments or improvements in control
technologies.
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Chapter 1: Introduction and Background
Table 1.6. Other Regulatory Drivers That Influence Post-Construction Stormwater
Regulatory Driver
Link With Post-Construction Program
Federal (many programs passed down to states for administration)
NPDES Stormwater Permits
for Construction
www.epa.go v/npdes/
stormwater/construction
Applies to Stormwater discharges from sites with disturbance of 1 acre or greater. Requires
control of sediment and erosion and other wastes at the site. Operators must develop and
implement a Stormwater pollution prevention plan (SWPPP).
Provides opportunity for local program to coordinate construction and post-construction phases
in plan review, inspection, and maintenance.
NPDES Stormwater Permits
for Industrial Activities
www.epa.go v/npdes/
stormwater/msgp
Applies to Stormwater discharges from certain categories of industrial activity. Requires site-
specific SWPPP.
Post-construction program should ensure that new industrial facilities are designed to prevent
pollution and treat Stormwater runoff from industrial areas.
Other NPDES Permits (e.g.,
wastewater discharge, etc.)
www.epa.go v/npdes
Regulates discharges of process wastewater from municipal, commercial, and other wastewater
treatment facilities.
Combined Sewer System -
Long-Term Control Plan
(NPDES)
www.epa.go v/npdes/cso
Requires plan to address and minimize overflows from combined systems to waters of the U.S.
Some communities have both an MS4 and a combined sewer system, and management practices
should be coordinated. For instance, practices that limit the volume of Stormwater discharges can
also help reduce the incidence of CSOs. In addition, treatment practices such as street sweeping
and catch basin cleaning can reduce floatables and sediment in CSOs.
Total Maximum Daily Load
(TMDL)
www.epa.gov/owow/fm o7
Addresses impaired waters through a program that develops total maximum daily loads (TMDLs).
A TMDL is a calculation of the maximum a mount of a pollutant that a waterbody can receive and
still meet water quality standards.
Post-construction programs specify Stormwater practices, retrofits, and/or site-based load limits
for development and redevelopment that can address the pollutant(s) identified in the TMDL.
Source Water Assessment
Program, Wellhead
Protection Program, and
Underground Injection
Control Program
www.epa.gov/ogwdw
Identifies and maps potential threats to water supply sources, and recommends protection plans.
Stormwater facilities and retrofits can help protect water supply watersheds and wellhead areas.
Certain practices may be limited, such as infiltration within wellhead protection areas.
Hotspot land uses and discharges may be restricted.
Federal Wetland Permits
(Section 404)
www.epa.gov/wetlands
Regulates the discharge of dredged and fill material into waters of the United States, including
wetlands.
Stormwater practices that negatively impact streams and wetlands require permitting and are
subject to denial.
May push programs and site choices into low-impact development strategies to avoid impacts.
Stormwater plans may have to be coordinated with mitigation plans required through the
wetland permitting process.
Coastal Zone Management
Program (CZMP)
http://coastalmanagement.
noaa.gov
Sets out planning goals and milestones for designated coastal zones.
Stormwater controls should be coordinated with state-specific coastal zone management plans,
which may include BMP performance standards.
Nonstructural measures, such as wetland and marsh protection, can be incorporated into
Stormwater strategy to mesh with CZMP objectives.
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Chapter 1: Introduction and Background
Table 1.6. Other Regulatory Drivers That Influence Post-Construction Stormwater (continued)
Regulatory Driver
Link With Post-Construction Program
Homeland Security
www.dhs.gov and
www.epa.gov/waferseci/rify
Includes protection of drinking water supplies and wastewater systems as elements of the
homeland security efforts of EPA and DHS. The Federal Emergency Management Agency (FEMA)
is also a Homeland Security agency, and participation in the National Flood Insurance Program
(NFIP) can be influenced byfloodplain development policies and Stormwater management.
National Flood Insurance
Program
www.fema.gov/about/
programs/nfip
Allows local program to set standards for Stormwater facilities located in floodplains (especially if
fill is required) to ensure that flood conveyance is not impeded.
Stormwater facilities may be factored into local floodplain modeling
State (variable by state)
Dam Safety Program
Establishes regulatory overlay for impounding structures over a certain size or capacity, requiring
regulatory coordination between local and state programs.
State Erosion and
Sediment Control and
Stormwater Programs
Provides performance and/or technology standards for construction Stormwater plans and
facilities.
In most cases, requires coordination between construction and post-construction program
elements, such as plan reviews and inspections.
State Water Supply Criteria
Where present, establishes standards for water supply planning and management that may
include buffers and setbacks and/or Stormwater treatment criteria. These should be coordinated
with the local program.
State Scenic River, Open
Space, Reforestation,
and Resource Protection
Programs
Where present, includes state-specific goals with linkto Stormwater management, such as
setbacks from particular rivers.
State Well and Septic
Permitting Programs
Provides standards for location of wells and septic fields that may impact on-lot practices, such as
rain gardensand dry wells.
Regional
Specific Regional Efforts;
e.g., Chesapeake Bay, Great
Lakes, Puget Sound
Where present, provides regional plans and programs that may have goals, objectives, and/or
standards that influence a local Stormwater program.
Local
Existing Codes for Erosion
Control, Stormwater,
Zoning, Subdivision,
Standing Water and Weeds
(Nuisance), etc.
Establishes local rules for development density, streets, setbacks, etc. These codes may either
support or impede Stormwater program goals that aim to reduce impervious cover.
Greenway, Open Space,
Recreation Plans, etc.
Provides planning framework that offers opportunity for coordination between Stormwater
and planning (e.g., riparian restoration in conjunction with greenway development, Stormwater
demonstration sites at public parks).
Managing Stormwater in Your Community
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Chapter 1: Introduction and Background
Table 1.7. Current Trends and Recommended Actions for Post-Construction Program
Current Trends
Recommended Actions
Post-Construction Program Development
>• Most Phase II MS4s operate program with $10Kto $50K
budget.
General fund constitutes most of budget.
Most programs have two or fewer staff working on post-
construction stormwater.
Develop a post-construction program plan and budget to
achieve a desired level of service.
Seeka dedicated source of funding, such as a stormwater
utility, for post-construction stormwater management.
See Chapter 2, Tools 1, 2.
Linking Stormwater to Land Use Planning
>• For many programs, stormwater managers do not work
closely with land use planners.
Stormwater is considered after major land use decisions
have been made.
Build stronger link between stormwater program and the
comprehensive plan and land use decisions.
Use watersheds to organize stormwater and land use.
See Chapter 3, Tool 4.
Stormwater Management Approach & Criteria
Most local programs address flooding, and an increasing
number also deal with water quality and channel
protection.
>• Fewer programs address groundwater recharge, reduction
in overall runoff volume, or protection of sensitive receiving
waters.
Develop a more holistic approach for post-construction
stormwater management, including site design, source
controls, stormwater practices, and protection of sensitive
receiving waters.
Distill a stormwater approach into criteria to be incorporated
into ordinances and design guidance manuals.
See Chapter 4, Tool 3.
Post-Construction Stormwater Ordinance
>• Approximately half of Phase II MS4s have adopted
ordinance.
Adopt a post-construction stormwater ordinance in
conjunction with or separate from ordinances for construction
stormwater (erosion and sediment control) and illicit discharge
detection and elimination.
See Chapter 5, Tool 3.
Post-Construction Stormwater Guidance Manual
>• About 75% of states have some type of stormwater manual,
but many manuals are out-of-date.
>• Most state and local manuals do not provide incentives
or credits for low-impact development and innovative
practices.
Develop local design guidance, referencing the most
appropriate state, regional, or local manual for BMP design
standards.
If not already provided, build in credits for low-impact
development and innovative BMPs.
See Chapter 6, Tools 5,8.
Stormwater Plan Review Process
>• Most programs lack adequate staff to fully review
stormwater plans.
>• The average plan reviewer reviews 70 to 100 plans peryear.
Stormwater is considered late in the development review
process.
Develop adequate in-house staffing or consider outsourcing
the review function.
Use pre-submittal meetings and concept plans to ensure that
stormwater is considered early in the site planning process.
See Chapter 7, Tool 6.
Managing Stormwater in Your Community
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Chapter 1: Introduction and Background
Table 1.7. Current Trends and Recommended Actions for Post-Construction Program (continued)
Current Trends
Recommended Actions
Inspection of Post-Construction BMPs During Installation
Most local programs conduct general construction
inspections but might not focus on proper installation of
post-construction BMPs.
Many post-construction BMPs are not installed correctly.
Inspect post-construction BMPs at critical installation
milestones.
Develop standard forms and checklists for inspection staff.
Establish adequate enforcement procedures.
See Chapter 8, Tools 6, 7.
Post-Construction Maintenance
Most Phase II MS4s do not have an established
maintenance program.
>• Over half of programs do not use maintenance agreements.
>• Lack of maintenance is the single most important cause of
failure for BMPs and stormwater programs.
Clearly assign maintenance responsibility through policies,
maintenance agreements, and easements.
Develop a maintenance inspection and tracking program.
Conduct outreach to responsible parties.
See Chapter 9, Tool 6.
Program Tracking, Monitoring, and Evaluation
>• MS4s must establish measurable goals.
>• Although annual reports are submitted, many programs do
not evaluate their programs or develop useful indicators of
success.
Develop a combination of outcome-based and output-based
minimum measures to gauge program success and develop
annual reports.
Use evaluations to set program priorities, build public support,
and demonstrate compliance.
Maintain proper documentation to prepare for a potential
regulatory audit.
See Chapter 10.
Download Tools at: www.cwp.org/postconstruction
Managing Stormwater in Your Community
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Chapter 1: Introduction and Background
Managing Stormwater in Your Community
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Chapter
Post-Construction
Program Development-
Assessing Your Program
Chapter 1
Introduction &
Background
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 3
Linking Stormwaterto
Land Use
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Stormwater Program
Self-Assessment
Program & Budget
Planning
Companion Tools for Chapter 2
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
• Assessing Your Watershed & Community
Geographic Information
Demographic Information
Water Resources Information
Conducting a Post-Construction Program
Self-Assessment
Post-Construction Program Planning
3 Developing a Post-Construction Program Plan
Stormwater Program Funding Options
Managing Stormwater in Your Community
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Chapter 2: Post-Construction Program Development—Assessing Your Program
2.1. Assessing the Watershed and Community
The first step in developing a post-construction
stormwater program is to collect several types of basic
information about the watershed and community
to help make informed decisions on priorities and
pollutants of concern:
Geographical
Demographic/community
Water quality
The list below is a starting point; additional informa-
tion will likely be needed to address the unique issues
in a particular community.
Geographical Information
A locality's planning or public works departments will
likely have many maps and other relevant geographi-
cal information. For example, soil, slope, geology,
floodplain, and other natural hazard maps can identify
areas where new development is most appropriate
and where it should be avoided. Key information to
collect includes:
Maps
- watersheds
-floodplains
-soils
- land use
- land cover
- water resources (rivers, lakes, wetlands, etc.)
- source water protection areas
- roads
Precipitation
Areas prone to flooding
Several examples of these types of maps are shown in
Figure 2.1.
Source: Center for Watershed Protection
www.cwp.org
Source: USDA, Agricultural
Research Service
http://www.tucson.ars.ag.gov/unit/
gis/soils.html
Source: USDA, Natural Resource Conservation Service
http://manoawatershed.oceanit.com/NRCS/index.php
Source: USDA, Natural Resource Conservation
Service
h ttp://www.ct. n res. usda.go v/p rograms/CSP/
landuse-landcover-housatonic.html
Figure 2.1. Example maps for post-construction program development: (A) watershed delineation, (B) soils,
(C) floodplain delineation, (D) land use/land cover
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Chapter 2: Post-Construction Program Development—Assessing Your Program
Demographic and Community Information
It is important to understand the community's current
population and land use in order to identify where
growth is occurring and opportunities for redevelop-
ment. In addition, the program should address antici-
pated future growth. Will it be primarily residential on
the urban fringe, urban redevelopment, or another
form? A stormwater manager should also analyze the
past 1-3 years of recent construction projects to assess
relative site size (very large mixed use projects vs.
relatively small commercial/residential development),
type (residential vs. commercial), and other issues. Key
information to collect includes:
Current population
Anticipated population growth/change
Current land use and zoning
• Proposed changes to land use
Build-out analysis showing full development
potential of existing zoning (see Figure 2.2 for an
example)
Impervious cover
Construction projects (number, type, etc.)
• Transportation, utility, and infrastructure plans
Water Quality Information
Water quality information will help identify the pollut-
ants of concern and associated impaired waterbodies
in the community and surrounding area. The post-con-
struction program should be designed to reduce these
pollutants of concern and specifically address impaired
waterbodies. Key information to collect includes:
• Monitoring stations
• Groundwater: location of public wells, source water
protection areas, etc.
Existing water quality criteria and designated uses
303(d) impairments
• TMDLs
Areas of local concern, such as eroded channels or
water quality problem areas
• Other local waters in need of protection: high-value
streams, lakes, and reservoirs
See Figure 2.3 for examples of these types of maps.
After collecting information on the watershed and
community, the next step is to conduct a program
assessment of the post-construction program.
Sucwalershed Boundary
Impervious Cover Classifications
B Sensitive
Sens iti ve/lmpacled
[ Imparted
| I m pad edVN on-Supporting
^| Non-Supporting
Figure 2.2. The map on the left shows existing impervious cover by watershed. The map
on the right shows future impervious cover based on a build-out analysis
using existing zoning codes in the Appoquinimink watershed (Source:
Kitchell, 2003). The impervious cover classifications are based on the Center
for Watershed Protection's Impervious Cover Model (CWP, 2003a).
Managing Stormwater in Your Community
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Chapter 2: Post-Construction Program Development—Assessing Your Program
&*
a
Source water protection areas
Areas with karst geology
.
Impaired streams
Flood control impoundments
Figure 2.3. Examples of mapping of water resources information from Augusta County, Virginia (County of
Augusta, 2007)
2.2. Conducting a Post-Construction Program
Self-Assessment
Tool 1: Program Self-Assessment is a tool to help
assess the existing status of a post-construction
program and to identify key action items to address
identified gaps. The program assessment asks ques-
tions to evaluate the program based on a continuum
of program sophistication. The questions are divided
into three subgroups, or types of communities:
Group A (Initiating the Program). These
communities are initiating a stormwater
management program, which might be a variation
of an existing drainage and engineering program
or an entirely new program. The elements in this
subgroup should be accomplished by the end of
the first permit term.
Group B (Enhancing the Program). Communities
at this stage have a stormwater management
program in place, but seek program enhancement
to meet new stormwater rules or address growing
stormwater issues. The elements in this group
represent important enhancements that are
necessary for an effective program.
Group C (Advancing the Program). Communities
at this stage have more advanced stormwater
programs that focus on a more refined match of
BMPs to stormwater-related impacts, incorporating
monitoring and innovative land and watershed
planning techniques.
The Program Self-Assessment tool (Tool 1) includes
instructions on how to complete the program
assessment. For identified gaps, the stormwater
Managing Stormwater in Your Community
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Chapter 2: Post-Construction Program Development—Assessing Your Program
manager is directed to specific chapters of this guide
to help identify both short-term and long-term action
items and measurable goals.
Before embarking on any self-assessment, however, it
is important to scope out the state and NPDES require-
ments that apply to the post-construction program.
Specific requirements for post-construction that are
included in the MS4 permit should be addressed in the
program self-assessment and action items.
Note that in addition to the Program Self-Assessment
tool, the stormwater manager can also refer to EPA's
MS4 Program Evaluation Guidance when conducting
a post-construction assessment. Chapter 4.5 of
the evaluation guide addresses post-construction
programs. Although written primarily for EPA and state
inspectors, the evaluation guide is also helpful for
municipalities that wish to conduct a self-assessment
of their stormwater program. A copy of the MS4
Program Evaluation Guidance is available at
wwiv.epa.gov/npofes/sformivafer.
2.3. Post-Construction Program Planning
After collecting information on the community and
watershed and conducting a program self-assessment,
the stormwater manager will need to develop the post-
construction program (or enhance an existing program).
The first decision will be to articulate overall goals for
post-construction stormwater runoff in the community.
Some example goals of the program could include:
Meet regulatory requirements.
• Improve water quality and habitat conditions in
the community's watersheds (rivers, streams, lakes,
coastal waters, wetlands).
• Address flood risks and potential property damage.
Improve the planning and development process.
• Support redevelopment within infill and enterprise
zones.
• Integrate local plans and ordinances to ensure
comprehensive watershed planning.
Encourage site planning and stormwater
techniques, such as low-impact development and
green infrastructure practices, that best replicate
pre-development hydrologic conditions.
For many communities, multiple goals guide program
development. Deciding on the overall goal(s) for post-
construction will help to design an effective program.
Developing The Post-construction Program Plan
The community and watershed assessment and
post-construction program self-assessment (Tool 1)
will identify the potential "gaps" in the post-construc-
tion program. Not all gaps need to be addressed right
away. These gaps should be prioritized in relation to
the resources needed and available to develop various
program elements. A detailed post-construction pro-
gram plan will help secure the resources and funding
needed to implement the program.
A common program approach is to create a phased
implementation plan. In this way, staff, resources, and
budgets can be phased in overtime—likely tied to the
MS4 permit cycle.
Tables 2.1 through 2.3 provide a template for develop-
ing a comprehensive post-construction program plan.
The three tables represent three different phases of
program development:
Phase 1: Program Development, Linking
Stormwater to Land Use, and Adopting an
Ordinance
Phase 2: Developing or Adapting a Stormwater
Guidance Manual and the Stormwater Plan Review
Process
Phase 3: Inspecting Permanent Stormwater BMPs
During Construction, Developing a Maintenance
and Inspection Program, and Tracking and
Evaluating the Program
The tasks listed in each phase follow the chapters of
this guidance manual, and the tables reference relevant
manual sections and tools that can be used to assist
with each subtask. These tables are meant to provide
a template for a generic program, and each individual
program should tailor the tasks and subtasks to its own
program needs. (There is no "one size fits all" approach
to stormwater program planning.)
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Chapter 2: Post-Construction Program Development—Assessing Your Program
Table 2.1. Phase 1 of a Comprehensive Program Plan
Phase I Task
Relevant Guide
Section or Tool
1. Program Development
l.a. Assess Watershed and Community
l.b. Conduct Program Self-Assessment
I.e. Develop Program Goals, Plan, and Budget
l.d. Develop and Implement Public Involvement Strategy
I.e. Hire Core Program Staff
2.1
2.2, Tooll
2.3, Tool 2
All Chapters
2.3
2. Link Stormwater to Land Use
2.a. Establish Links to Planning Department
2.b. Evaluate Existing Land Use Codes
2.c. Assess Integrated Stormwater/Land Use Tools
2.d. Adopt Land Use Policies That Support Water Quality Goals
3. Adopt or Amend Stormwater Ordinance
3. a. Develop Stormwater Approach and Relevant Criteria for the Community
3.b. Identify MS4 Permit Requirements and Commitments
3.c. Identify State, Regional, or National Model Ordinance
3.d. Decide Whether to Integrate Ordinance with Construction Stormwater and IDDE
3.e. Develop and Implement Stakeholder Participation Plan
3.f. Develop Draft Ordinance
3.g. Estimate Plan Review, Inspection, and Maintenance Resource Burden
3.h. Adopt Ordinance Through Public Process
3.7
3.6, Tool 4
3.8
Ch.3
Ch.4
1.6, state general permits
5.1, Tool 3
5.2
5.5
Ch. 5, Tool 3
Chs. 7, 8, 9
Ch.5
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Chapter 2: Post-Construction Program Development—Assessing Your Program
Table 2.2. Phase 2 of a Comprehensive Program Plan
Phase 2 Task
4. Develop and/or Utilize Relevant Stormwater Guidance Manual(s)
4.a. Scope Out Design Guidance Task
4.b. Identify Local, State, or Regional Manual to use as Model or By Reference
4.c. Decide Whether to Integrate Manual with Construction Stormwater (erosion and sediment
control manual)
4.d. Develop and Implement Stakeholder Participation Plan
4.e. Develop/Reference Policy and Procedures Manual
4.f. Develop/Reference Technical Design Manual
4.g. Adopt the Manuals Through Public Process
4.h. Provide Training on Use of Manuals
4.g. Update the Manuals at Least Every 5 Years
Relevant Guide
Section or Tool
6.4
6.11, Tool 5
1.2,6.4
6.13
6.5, Tool 5
6.6 -6.10, Tool 5
6.12,6.13
6.13
6.4,6.12
5. Create or Enhance Stormwater Plan Review Process
5. a. Scope Out Plan Review Process
S.b. Decide Whether to Do Review In-House or Outsource
S.c. Create Flowchart or Map Out Review Process
S.d. Create Forms, Applications, Instruction Materials, and Checklists for Applicants and Review Staff
S.e. Forecast Staff Needs and Acquire Staff
S.f. Provide Training for Review Staff and Design Consultants
S.g. Develop Web-based or Other Tracking System to Track Plans and Approvals
S.h. Set Up Performance Bond Process, Forms, and Tracking System
51 Review Stormwater Plans
7.3
7.5
7.4
7.4 -7.5, Tool 6
7.5, Tool 2
7.5
7.5,10.6
Tool 7
Ch. 7, Tool 6
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Chapter 2: Post-Construction Program Development—Assessing Your Program
Table 2.3. Phase 3 of a Comprehensive Program Plan
Phase 3 Task
6. Inspect Permanent Stormwater BMPs During Construction
6.a. Scope Out Inspection Process
6.b. Decide Whether to Use In-House Inspectors or Contractors
6.c. Create Checklists, As-Built Certification Forms, and Other Forms Needed for Inspection
6.d. Forecast Staff Needs and Acquire Inspection Staff or Use Existing Staff
6.e. Provide Training for Inspectors and Contractors
6.f. Develop Web-based or OtherTracking System to Track Inspections and Enforcement Actions
6.g. Inspect BMPs During Construction
7. Develop Maintenance and Inspection Program
7.a. Scope Out Maintenance Program
7.b. Decide on Maintenance Approach and Make Level of Service Policy Decisions
7.c. Decide Whether to Use In-House Inspectors or Contractors or Rely on Responsible Parties for
Maintenance Inspections
7.d. Decide Whether to Use In-House Resources, Contractors, or Responsible Parties for Routine and
Structural Maintenance Tasks and Repairs
7.e. Create Checklists, Inspection Forms.and Enforcement Tools
7.f. Forecast Staff and Equipment Needs and Acquire Resources
7.g. Create and Disseminate Outreach Materials for Responsible Parties
7.h. Develop Web-based CIS or OtherTracking System to Track Inspections and Enforcement
Actions
71 Inspect BMPs for Maintenance
7.J. Conduct Maintenance Tasks
8. Track, Evaluate, and Monitor the Program
8.a. Scope Out Evaluation and Monitoring Tasks
8.b. Decide on Measurable Goals and Tracking Indicators
8.c. Develop Tracking and Reporting Tools to Track Key Indicators
8.d. Write Annual Reports for Program Compliance and Other Program Reports and Documents
8.e. Maintain the Tracking System
Relevant Guide
Section or Tool
8.3
8.5
8.5, Tool 6
8.5, Tool 2
8.5-8.6
10.6
Ch.8
9.3
9.3, 9.4
9.4
9.4
9.4, Too 16
9.4, Too 12
9.6
10.6,10.7
9.5
9.5
10.3-10.5
10.4-10.9
Ch. 10
10.10
Ch. 10
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Chapter 2: Post-Construction Program Development—Assessing Your Program
Tool 2: Program and Budget Planning Tool is a
spreadsheet tool that enables the user to fill in the
staffing needs and expenses, other program expenses,
and potential revenue sources for each task and sub-
task identified in Tables 2.1 through 2.3. This is not a
detailed budgeting tool, but it can help with program
planning, goal setting, and phasing. This tool should
be modified by stormwater managers to fit the needs
and characteristics of their individual programs.
Another key program planning step is to ensure that
staff assigned to the program have the right skills or
can be trained to acquire them. Most local programs
have engineers working in administrative and tech-
nical capacities (CWP, 2006). Other personnel skills
that may be relevant for a post-construction program
include:
Land use and planning
Budget planning and management
Geographic information systems (CIS), global
positioning systems (GPS), database
Construction, inspections, facilities maintenance
• Capital project management
Water quality and biology
Hydrology
Legal
It is also important for the post-construction pro-
gram to have a lead department, division, or point of
contact within the government or agency structure.
Since post-construction often involves multiple staff
functions and departments, the lead agency provides
overall coordination and communication, and takes
responsibility for meeting program milestones. The
lead agency is often a public works department, but
lead agencies may also be departments or divisions for
community development, water and wastewater, envi-
ronmental programs, stormwater utilities, or elected
boards (CWP, 2006).
2.4. Stormwater Program Funding Options
Stormwater program managers have a wide range of
funding sources to finance implementation of these
programs, from general funds to dedicated sources
like stormwater utilities. The program manager must
assess each funding source to ensure it meets the
stormwater program needs. The National Associa-
tion of Flood and Stormwater Management Agencies
(NAFSMA), under a grant from EPA, has developed
Guidance for Municipal Stormwater Funding. This docu-
ment helps municipalities address the procedural,
legal, and financial considerations in selecting and
developing stormwater financing approaches. The
document is available at www.nafsma.org.
Candidate stormwater program funding sources
include:
Stormwater utilities
General funds
Clean Water State Revolving Fund (CWSRF) loans
Fees
Taxes
• Grants
Debt financing
Local improvement districts
Developer participation
• Additional fees (impact, plan review and inspection,
fee in lieu of on-site construction, system
development fees/connection charges)
Each of these funding sources has advantages and dis-
advantages that have to be evaluated for compatibility
with local needs. Furthermore, there are many other
factors to examine when evaluating each funding
source, such as state or local requirements, drainage
infrastructure needs, and the political climate.
Stormwater Utilities
A common source of funding for stormwater manage-
ment programs is the use of stormwater utilities and
stormwater fees. Property owners are charged fees for
the amount of stormwater produced on their property.
Managing Stormwater in Your Community
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Chapter 2: Post-Construction Program Development—Assessing Your Program
A stormwater utility is a mechanism to fund the cost
of operations and capital projects directly related to
the control and treatment of stormwater, including
staffing, permitting, inspections, public education,
watershed planning, and other program management
costs. The fees are typically based on factors that influ-
ence stormwater runoff, such as amount of impervious
surface, for a property and calculated using a predeter-
mined classification, such as the equivalent residential
unit (ERU), or another rate-setting methodology. In
addition, the utility is administered and funded sepa-
rately from the revenues in the general fund, which
ensures a reliable source of funding for stormwater
management.
Establishing a stormwater utility is a complex under-
taking, and it requires careful planning and public
outreach to be successful. The process usually involves
conducting feasibility studies and system inventories,
developing administrative and billing systems, mount-
ing extensive public information campaigns, devel-
oping policies on credits and exemptions, adopting
ordinances, and implementing the utility.
General Fund
The traditional source of funding for stormwater man-
agement programs is the jurisdiction's general fund.
These monies are usually generated from a variety
of sources, including taxes (e.g., income, sales and
property taxes), exactions (e.g., franchise fees on utili-
ties), and federal/state revenue sharing, and are simply
appropriated for specific purposes, including stormwa-
ter management, through the normal budget process.
In some cases, the revenues appropriated by the gen-
eral fund are sufficient to provide financial support for
the entire stormwater program. However, this source
of revenue is used to fund many other programs, and
revenues are variable and unpredictable. Elected offi-
cials must determine the relative priority of stormwater
management versus numerous other needs and ser-
vices. The unpredictable, political, and limited nature
of the general fund has pushed many stormwater
managers to pursue the stormwater utility approach.
Other Sources of Funding
Other funding sources are one-time grants (federal,
state, or local), loans or bonds, state revolving funds,
and additional fees that can cover costs of erosion and
sediment control, structural stormwater management,
upgrades or improvements to the program, opera-
tion and maintenance of sewers, acquisition of envi-
ronmentally sensitive land, and other environmental
initiatives.
Municipalities also have the option of using additional
funding strategies, such as impact fees, plan review
and inspection fees,fee-in-lieu payments, and system
development fees/connection charges to fund the
stormwater management program. Impact fees trans-
fer the cost of roads, sewers, stormwater treatment,
and other facilities needed for development directly
to developers and can relieve financial pressures on
the budget. In addition, plan review and inspection
fees can be charged to cover the costs of reviewing
development plans, inspecting BMPs, and ensuring
that development plans are properly implemented.
Another funding strategy is to develop a fee-in-lieu
program whereby developers pay a fee to the local
program in lieu of partial or full on-site compliance
with BMP requirements. The local program, in turn,
uses the funds to conduct stormwater and watershed
projects, such as stormwater retrofits, stream and wet-
land restoration, and regional projects.
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Chapter
Land Use Planning as
the First BMP: Linking
Stormwater to Land Use
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Codes & Ordinance
Worksheet (COW)
Companion Tools for Chapter 3
Download Post-Construction Tools at:
www.cwp.org/postconstruction
Managing Stormwater in Your Community
What's In This Chapter
Why Stormwater managers should engage in land use
decisions
Planning at different scales
Regional
District or neighborhood
Site level
A process for integrating Stormwater and land use
planning
> Understand the role of impervious cover and
other watershed factors
Examine and evaluate land use codes
Develop relationships between Stormwater
managers, land use planners, and other officials
Use watersheds are organizing units
• Considering climate change in the storm water/land
use program
-------
Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
3.1. Introduction
Increasingly, communities are looking for ways to
maximize the opportunities and benefits associated
with growth while minimizing and managing the
environmental impacts of development. Balancing
these priorities is playing out in planning commission
meetings, boardrooms, mayors' offices, and public
meetings throughout the United States. Stormwater
managers can, and should, be central players in such
conversations. Where and how development occurs
can dramatically affect a community's watersheds,
infrastructure, and water supplies. Effectively engag-
ing in these discussions can help communities better
balance development decisions with environmental
protection.
The barrier, however, is where and how to engage in
development decisions. Traditionally, the practice of
Stormwater management has been limited to site-level
approaches. However, Stormwater management is
evolving beyond engineered approaches applied at
the site level to an approach that looks at managing
Stormwater at the regional, district/neighborhood, and
site scales.
By looking at Stormwater management at various
scales, Stormwater managers can influence the devel-
opment debate in a number of ways. For example,
they can, and should, be active in helping a commu-
nity craft policies and incentives to direct development
to already disturbed or degraded land. Redeveloping a
parking lot, abandoned mall, or already degraded site
allows a community to enjoy the benefits of growth
without increasing net runoff. In this way, engaging in
growth and development discussions can be consid-
ered the "first Stormwater best management practice."
The purpose of this chapter is to highlight opportu-
nities where Stormwater managers can engage in
broader growth and development decisions. Every
community is unique and has it own vision of its char-
acter. Certainly, a development discussion concerning
redevelopment of an aging downtown area will cover
issues substantially different from those of a rural town
struggling to maintain its character. Both communities,
however, will discuss policies and regulations, such
as road and street width, building setbacks, parking
requirements, and open space requirements, that can
have a direct impact on Stormwater runoff.
This chapter seeks to highlight those development-
related policies and regulations and describe how
Stormwater managers might effectively engage and
influence land use decisions.
3.2. Why Should Stormwater Managers Engage
in Land Use Decisions?
Many Stormwater managers do not see engaging in
land use decisions as part of their job. Indeed, the past
few decades of Stormwater management have focused
on using control and treatment strategies that are
largely hard-infrastructure-engineered, end-of-pipe,
and site-focused practices concerned primarily with
peak flow rate and suspended solids concentration
control.
Where and how communities grow affects water qual-
ity. The collective experience of communities across
the United States demonstrates that looking only at
site-level practices will not repair damaged waterbod-
ies and will likely put more streams on impaired lists
over time.
Indeed, factors at the site, district/neighborhood, and
regional scales can drive the creation of unnecessary
impervious cover and other land cover conditions that
produce excessive runoff. These factors are embed-
ded in a community's land use codes and policies. A
comprehensive approach to Stormwater management
should therefore include an examination of a locality's
land development regulations, policies, and ordi-
nances to better align with water quality goals.
For example, a subdivision ordinance dictates mini-
mum houses per acre, street width, and the distance a
house is set back from the road. All of these measures
create impervious surface. It is for the municipality to
determine whether the creation of this impervious
surface and the generation of the associated runoff
are appropriate. In this way, the municipality aligns its
subdivision regulations with its Stormwater goals.
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Table 3.1 lists common land use development regula-
tions, codes, and policies that could be reviewed for
consistency with stormwater goals. These documents
are also needed to complete the "Codes and Ordi-
nance Worksheet," which is a tool to assist with the
systematic review of codes and policies for consistency
with model development principles (see Tool 4).
A comprehensive approach to stormwater manage-
ment involves developing stormwater management
practices that can be applied at the regional, district/
neighborhood, and site scales. It also involves look-
ing at where and how development occurs within the
community. This is best done by examining com-
mon land development regulations and policies that
dictate the location, quantity or density, and design of
development.
3.3. Planning at Different Scales
Decisions about where and how to grow are the first,
and perhaps most important, development decisions
related to water quality. A comprehensive stormwater
management approach supports an interconnected
network of open spaces and natural areas (such as
forested areas, floodplains and wetlands) that improve
water quality while also providing recreational oppor-
tunities and wildlife habitat. These open spaces must
be balanced with areas where growth and devel-
opment are appropriate. Traditionally, stormwater
managers have engaged at the development site level
by restricting development within the riparian buffer,
wetlands, or other critical natural features. However,
engaging in this issue at the district/neighborhood
scale or regional scale can have a greater water quality
benefit.
A 2006 EPA study found that, conceptually, higher-
density development can be more protective of
regional water quality than lower-density scenarios
because less stormwater and associated pollutants are
produced on a per-unit basis (USEPA, 2006a). Figure 3.1
illustrates how dense developments, although they
have a high site-level impervious cover, can result
in a lower watershed impervious cover compared
to a scenario where development is equally spread
out across the watershed. For example, in scenario C
development is directed to 1/8-acre lots in a small
Table 3.1. Common Land Use Development Regulations, Codes, and Policies That Can Drive Impervious Cover
>• Zoning ordinance specifies the type of land uses and intensity of those uses allowed on any given parcel. A zoning ordinance
can dictate single-use, low-density zoning, which spreads development out throughout the watershed, creating excess
impervious cover.
Subdivision codes or ordinances specify specific development elements for a parcel: housing footprint minimums, distance
from the house to the road, the width of the road, street configuration, open space requirements, and lot size—all of which
can lead to excess impervious cover.
Street standards or road design guidelines dictate the width of the road for expected traffic, turning radius, the distance for
other roads to connect to each other, and intersection design requirements. Road widths, particularly in new neighborhood
developments, tend to be too wide, creating considerable impervious cover.
>• Parking requirements generally set the minimum, not maximum, number of parking spaces required for retail and office
parking. Setting minimums leads to parking lots designed for peak demand periods, which can create acres of unused
pavement during the rest of the year.
>• Minimum setback requirements can spread development out by leading to longer driveways and larger lots. Establishing
maximum setback lines for both residential and retail development brings buildings closer to the street, reducing the
impervious cover associated with long driveways, walkways, and parking lots.
Site coverage limits can disperse the development footprint and make each parcel farther from its neighbor, leading to more
streets and roads and thereby increasing total impervious cover throughout the watershed.
Height limitations limit the number of floors for any building. Limiting height can spread development out if square footage
cannot be met by vertical density.
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Scenario A
10,000 houses built on 10,000 acres
produce:
10,000 acres x 1 house x 18,700 ftVyr
of runoff =
187 million ft3/yr of stormwater
runoff
Site: 20% impervious cover
Watershed: 20% impervious cover
Scenario B
10,000 houses built on 2,500 acres
produce:
2,500 acres x 4 houses x 6,200 ftVyr
of runoff =
62 million ft3/yr of stormwater
runoff
Site: 38% impervious cover
Watershed: 9.5% impervious
cover
1
10,000 houses built on 1,250 acres
produce:
1,250 acres x 8 houses x 4,950 ftVyr
of runoff =
49.5 million ft3/yr of stormwater
runoff
Site: 65% impervious cover
Watershed: 8.1% impervious
cover
Figure 3.1. Watershed impervious cover at different development densities (Source: U.S. EPA, 2006a)
portion of the watershed, resulting in 65% impervious
cover for the development site but only 8% impervious
cover for the entire watershed. If an equivalent
number of development units are spread out over the
entire watershed (scenario A), the development has a
lower impervious cover but the watershed has a much
higher impervious cover, 20%.
The following sections describe potential approaches
a stormwater manager can take to address stormwater
at the regional, district/neighborhood, or site scale.
Regional Stormwater Management Approaches
Stormwater managers should begin to address storm-
water at a regional scale by doing the following:
Preserving open space and critical ecological
features. Preserving open space is critical to
maintaining water quality at the regional level.
Large, continuous areas of open space reduce
and slow runoff, absorb sediments, serve as flood
control, and help maintain aquatic communities.
Preserving ecologically important land, such as
wetlands, buffer zones, riparian corridors, and
floodplains, is critical for regional water quality.
Encouraging development in already-degraded
areas. Perhaps the biggest opportunity for
any stormwater manager is to work with local
governments to develop a range of policies and
incentives to direct development to already
degraded areas. Communities can enjoy a significant
reduction in regional runoff if they take advantage
of underused properties, such as infill, brownfield, or
greyfield sites (sites in abandoned or underutilized
commercial areas) (Congress for New Urbanism,
2001). Redeveloping already degraded sites such
as abandoned shopping centers or underutilized
parking lots rather than paving greenfield sites for
new development can dramatically reduce total
impervious area and water quality impacts.
Using land efficiently. Using land efficiently
reduces and better manages stormwater runoff by
putting development where it is most appropriate
and reducing total impervious area. For example, by
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directing and concentrating new development in
areas targeted for growth, communities can reduce
or remove development pressure on undeveloped
parcels and protect sensitive natural lands and
recharge areas.
District or Neighborhood Stormwater
Management Approaches
Stormwater at the district or neighborhood scale can
be addressed through approaches, like the following:
Mixed use and transit-oriented development.
Mixing land uses can have direct effects on reduc-
ing runoff because mixed-use developments
have the potential to use surface parking lots and
transportation infrastructure more efficiently,
requiring less pavement. Transit-oriented develop-
ment can help protect water quality by reducing
(1) land consumption due to smaller site footprints,
(2) the number of parking spaces, and (3) average
vehicle miles traveled, which in turn reduces
atmospheric sources of pollution that can end
up in receiving waters. Because higher-density
development is clustered around transit stops, the
need for developing land elsewhere in a region can
be reduced (if the proper policies and controls are
in place).
Green streets. The green streets concept is a
streetscape design with multiple functions that
integrates the "natural" and the "manmade." Green
street streetscapes facilitate natural infiltration
wherever possible and therefore have less
impervious surface such as concrete and asphalt.
They allow for greater use of vegetation and other
attractive materials, such as crushed stone and
pavers, which can help to create an identifiable
community character.
Parking requirements. Another strategy to reduce
impervious cover is to assess parking requirements,
particularly those for parking lots. Better balancing
parking demand and supply could help remove
some of the excess spaces. Some communities have
found that "park once," shared parking strategies,
and allowing on-street parking can help balance
parking supply and demand. In 2006 EPA published
Parking Spaces/Community Places: Finding the Balance
Through Smart Growth Solutions. This document
highlights approaches that balance parking with
broader community goals (USEPA, 2006b).
Open-space amenities. In recent decades Americans
have demonstrated their preference for living near or
adjacent to parks or other open-space areas by their
willingness to pay a premium for housing near these
amenities (Trust for Public Land, 1999). Nationwide,
easy access to parks and open space has become a
measure of community health. These district/neighbor-
hood open spaces can also serve critical Stormwater
functions, such as providing buffer areas for Stormwater
quality or areas to reduce Stormwater flooding.
Site-level Stormwater Management Approaches
After minimizing runoff at the regional and district/
neighborhood scales, Stormwater management finally
turns to the site scale. Many of the remaining chapters
in this guide focus on site-level Stormwater strategies.
For instance, Chapter 4 includes a recommended
Stormwater management approach that is largely
relevant to the site scale.
Smart Growth Approaches to Stormwater
Management
Table 3.2 lists various EPA publications about the rela-
tionship between planning and water quality that are
relevant to water resources and Stormwater manage-
ment. It should also be noted that EPA's National Menu
of Stormwater Best Management Practices lists many
Smart Growth and site design techniques among
post-construction best management practices (BMPs;
see Table 3.3). EPA encourages a mix of structural,
nonstructural, and planning techniques to address the
post-construction minimum measure.
The remainder of this chapter introduces a process
for integrating Stormwater with land use planning. In
other words, it outlines how a Stormwater program
can consider land use as the "first BMP" by integrat-
ing ideas and techniques that engage the Stormwater
manager in land use issues.
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Table 3.2. EPA Publications Related to Water Resources and Stormwater
Note: See iviviv.epa.gov/smarfgroivf/) for more information.
Using Smart Growth Techniques as Stormwater Best Management Practices, EPA231-B-05-002. December 2005.
www.epa.gov/smartgrowth/stormwater.htm
A guidance document that reviews nine common smart growth techniques and examines how they can be used to prevent
or manage Stormwater runoff.
Protecting Water Resources with Higher-Density Development, EPA 231-R-06-001. January 2006.
www.epa.gov/smartgrowth/water_density.htm
A guidance document that helps communities better understand the impacts of higher- and lower-density development
on water resources. The findings indicate that low-density development might not always be the preferred strategy for
protecting water resources.
Parking Spaces/Community Places, EPA 231-K-06-001. January 2006.
http://www.epa.gov/smartgrowth/parking.htm
A guidance document that helps communities explore new, flexible parking policies that can encourage growth and
balance parking needs with their other goals.
Protecting Water Resources with Smart Growth, EPA 231-R-04-002. May 2004.
www.epa.gov/smartgrowth/water_resource.htm
A guidance document intended for audiences that are already familiar with smart growth concepts and want specific ideas
on how smart growth techniques can be used to protect water resources. Suggests 75 policies that communities can use to
grow in the way that they want to while protecting their water quality.
Stormwater Guidelines for Green, Dense Redevelopment, December 2005.
www.epa.gov/smartgrowth/emeryville.htm
A City of Emeryville, California, grant product that is geared specifically to developers and designers. These guidelines offer
ways to meet requirements to treat Stormwater from development projects.
Solving Environmental Problems through Collaboration^ Case Study of the New York City Watershed Partnership, EPA 231 -F-06-005.
June 2006.
www.epa.gov/innovation/collaboration
A fact sheet that provides a summary of the partnership, which works closely with government and nongovernmental
partners to protect the drinking water supply of 9 million people while promoting economic viability and preserving the
social character of the communities in the upstate watershed.
Growth and Water Resources, EPA 842-F-02-008. September 2005.
www.epa.gov/smartgrowth/pdf/growthwater.pdf
A fact sheet that explains how land use affects water resources and offers resources and tools for communities.
Growing Toward More Efficient Water Use: Linking Development, Infrastructure, and Drinking Water Policies, EPA 230-R-06-001.
January 2006.
www.epa.gov/smartgrowth/water_efficiency.htm
A guidance document that focuses on the relationships among development patterns, water use, and the cost of water
delivery and includes policy options for states, localities, and utilities that directly reduce the cost and demand for water
while indirectly promoting smarter growth.
Smart Growth for Clean Water. National Association of Local Government Environmental Professionals, Trust for Public Land,
ERG. 2003.
www.resourcesaver.com/file/toolmanager/CustomO93C337F42157.pdf
A grant product that offers ideas for using smart growth to advance clean water goals based on the experiences of
communities across the nation.
Potential Roles for Clean Water State Revolving Fund Programs in Smart Growth Initiatives, EPA 832-R-00-010. October 2000.
www.epa.gov/ow/T7/cwfirtartce/cwsrf/rcicfsrieefs.rifm
A guidance document that describes options for states to use their Clean Water State Revolving Funds to support more
environmentally sound growth and development.
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Table 3.3. EPA's National Menu of Stormwater Best Management Practices:
Selected Post-Construction BMPs Consistent with Smart Growth
and Site Design Strategies
www.epa.gov/npdes/menuofbmps
>• Conservation Easements
Development Districts
>• Eliminating Curbs and Gutters
>• Green Parking
Green Roofs
>• Infrastructure Planning
>• Low-Impact Development and Green Design Strategies
>• Narrower Residential Streets
>• Open-Space Design
>• Protection of Natural Features
Redevelopment
>• Riparian/Forested Buffer
Street Design and Patterns
Urban Forestry
3.4. A Process for Integrating Stormwater and
Land Use
The following four steps are recommended to begin
integrating Stormwater with land use:
1. Understand the role of impervious cover and
other watershed factors at the regional, district/
neighborhood, and site scales.
2. Examine and evaluate land use codes for drivers of
excess impervious cover and land disturbance.
3. Develop relationships between Stormwater
managers, land use planners, and other officials.
4. Use watersheds as organizing units for the linked
stormwater/land use program.
The following sections discuss each step in more
detail.
3.5. Step 1: Understand the Role of Impervious
Cover and Other Watershed Factors at the
Regional, District/Neighborhood, and Site
Scale
Impervious cover has become one of the most impor-
tant indicators of overall watershed health because it
is relatively easy to measure and the correlations with
stream health have been documented for small water-
sheds draining first- to third-order streams (e.g., 2 to 20
square miles) (CWP, 2003a; Schueler et al., in review).
Thus, controlling overall impervious cover at the water-
shed or community level is one of the chief strategies
currently employed to limit Stormwater impacts.
Though development in various watersheds is highly
varied, research finds that indicators of stream health
decline with increasing impervious cover (CWP, 2003a;
Schueler et al., in review). Figure 3.2 presents a con-
ceptual model that expresses the impervious cover/
stream health relationship as a "cone" that is widest
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
these factors and stream health, and to develop strate-
gies to manage them (e.g., adopting regulations that
require conservation of forest buffers). Nevertheless,
impervious cover remains an important watershed
metric for stormwater managers to track and manage.
The factors that drive the proliferation of impervious
cover within watersheds are often embedded within
complex land development codes and standards.
These same codes and standards can also influence
other land cover metrics that affect watershed health,
such as the amount and location of forest cover pres-
ent in the watershed. Before undertaking a large-scale
program review, it is helpful to understand the factors
that shape impervious cover and other land cover
types in the built environment.
As discussed earlier in this chapter, these factors
operate at three different scales: (1) the region, (2) the
district or neighborhood, and (3) the site. The actual
codes and policies that operate at these three scales
are examined in more detail in the following section.
3.6. Step 2: Examine and Evaluate Land Use
Codes for Drivers of Excess Impervious Cover
and Land Disturbance
As explained at the beginning of this chapter, there are
factors at the site, district/neighborhood, and regional
scales that are hidden drivers of impervious cover. The
next step in the process of linking stormwater to land
use planning is to pry into these codes and policies to
see if they can be made more consistent with overall
stormwater management goals. For instance, if the
local zoning code requires wide streets with curbs and
gutters, perhaps alternative designs with less pave-
ment and more vegetation should be considered.
Table 3.4 lists the most common local development
codes and documents that should be reviewed for
consistency with stormwater goals. These documents
are also needed to complete the "Codes and Ordi-
nance Worksheet," which is a tool to assist with the
systematic review of codes and policies for consistency
with Better Site Design model development principles
(see Tool 4).
Table 3.4. Key Local Documents to Review for
Consistency with Stormwater Goals
»• Zoning ordinance
Subdivision codes
Subarea or district master plans
Street standards or road design manual
Parking requirements
Building and fire regulations/standards
Stormwater management or drainage criteria
Buffer or floodplain regulations
Environmental regulations
Tree protection or landscaping ordinance
Erosion and sediment control ordinances
Public fire defense master plans
»• Grading ordinance
The following sections highlight some of the most
common local code and policy issues that might
conflict with good stormwater management.
Chapter 5 goes into more detail on developing
appropriate stormwater codes and how to identify
inconsistencies with existing regulations.
Code and Policy Issues That Drive Impervious
Cover at the SITE SCALE
Many codes and policies at the site scale can inadver-
tently increase impervious cover. For example, setback
requirements can lead to inefficient use of land by
spreading development out and creating the need for
longer driveways. Height limits can spread develop-
ment out if square footage cannot be met by going
up. Site coverage limits can disperse the develop-
ment footprint and make each parcel farther from its
neighbor, leading to more public infrastructure. Many
different parking requirements, including the following,
increase impervious cover:
Parking standards. Most land development
codes contain detailed specifications on parking
requirements that are based on bulletins from the
Institute of Transportation Engineers (ITE). The
bulletins, which are updated regularly, estimate
parking demand for various uses, which are then
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translated into site plan requirements. These
requirements are often listed as minimums. Often
the number of spaces is driven by a few high-
volume shopping days each year, and the studies
used to estimate parking demand are often carried
out in areas where the automobile is the only mode
of transportation considered. In addition, the extra
spaces trigger additional imperviousness in the
form of drive aisles, access lanes, and turn lanes
from roadways.
Parking requirements for redevelopment. Older
buildings might have fewer spaces than required
in updated parking codes. Redevelopment of
an older building often triggers the more recent
requirements. Where the older buildings are on
small lots, parking minimum requirements can be a
barrier to redevelopment.
Financial requirements. Developers who seek
financing often meet resistance to the idea of
supplying fewer spaces from lenders, who equate
extra parking spaces with lower financial risk.
• District-wide and shared parking. Perhaps one
of the larger, often unexplored drivers of excess
parking is the practice of assessing parking needs
one development project at a time. This precludes
the ability to arrange efficient parking supply
among users.
Use of streets. Some localities are discovering
on-street spaces as excess capacity for meeting
parking needs. The imperviousness is already there,
and thus using streets can alleviate the need to
construct more parking.
Code and Policy Issues That Drive Impervious
Cover at the DISTRICT/NEIHBORHOOD SCALE
At the district or neighborhood scale, impervious cover
can be driven by policies such as separated use poli-
cies, street design practices, and subdivision design.
These drivers are further discussed below:
• Separated uses. The zoning convention of
assembling development projects consisting of
a single use (e.g., all housing in subdivisions or all
commercial uses in office parks) has been widely
studied for impacts on travel, transportation,
and congestion. According to the Bureau of
Transportation Statistics, Americans average four
trips per day, totaling on average 40 miles of
travel, mostly in a personal vehicle. These trips, to
commute, shop, and recreate, are used as input to
models for parking requirements, travel demand,
and the like. For stormwater, these separated uses
result in an increased need for transportation
infrastructure, and its related imperviousness.
• Street design. In the 1950s and 1960s, roadway
design practices began to favor a less networked,
"hierarchical" street design. Within housing
subdivisions, the individual, smaller streets feed
into collector roads, which then lead, often through
only one intersection, to arterials. This type of
system concentrates traffic onto fewer roads, which
increases the pressure to build large public roads
or widen existing roads originally planned for rural
traffic patterns.
• Street and roadway widths. Ea rly roa dway
standards established minimum lane widths for
rural highways. Wider lanes were needed to provide
the sight clearance and maneuvering space needed
for higher speeds. Over time, these widths were
integrated into local street standards.
Roadway imperviousness is not limited to lane
widths. The size of turning and queuing lanes is
also governed by standard formulas. The wider
street standards brought with them higher design
speeds. These speeds, in turn, dictate the size of
intersections and curb radii, which are referred
to as "intersection geometry" in transportation
handbooks. For a full discussion of street geometry
and its relationship to site development, see
http://safety.fhwa.dot.gov/ped_bike/univcourse/
swless06.htm.
Subdivision design. Residential subdivision codes are
the primary example of a district code. Subdivision
codes (which are typically supported by enabling
legislation at the state level) include requirements
for roadways, drainage, open space, building
alignments, lot sizes, and many other features.
Planners have been working on improvements
to subdivision codes to eliminate some of the
commonly noted drawbacks, such as excessive
site clearance and the lack of mixed use. Planned
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unit developments (PUDs) often add a mixed-use
component to subdivisions, while conservation
subdivisions strive to lessen environmental
impacts by clustering home sites and preserving
open space within residential areas. Nevertheless,
conventional subdivision design still dominates site
planning and residential construction. A 2004 study
on subdivisions found street, driveway, and site
imperviousness composed up to 50% of the total
development site (Local Government Commission,
2004).
Code and Policy Issues That Drive Impervious
Cover at the REGIONAL SCALE
Impervious cover drivers at the regional scale can
include lack of coordination between units of
government, state standards, and transportation
requirements at the state/federal level. These drivers
are further discussed below:
• Lack of regional governance structures.
Jurisdictional boundaries often have the effect
of spurring competition, not cooperation. This
competition for tax base often leads to dispersed
growth. With stormwater, the permitted agency is
in many cases a relatively small unit of government,
such as a township or village. Decision-making at
this level is rarely coordinated at the watershed
scale.
• Codes and standards at the state level. States often
set requirements that result in a larger development
footprint. For example, school siting standards
often require at least 20,50, or even 100 acres for
new schools. School districts often find that the only
parcels of this size are in undeveloped areas. School
construction then generates new development
interest in the surrounding area.
Split responsibility for transportation. States
are usually responsible for Interstates, state
highways, and sometimes local roads. Localities
might be responsible for local roads and district/
neighborhood streets. Often, it is difficult to
coordinate transportation and land use planning
among the different agencies. Decisions to expand
or improve transportation systems at the state level
can run counter to local land use priorities.
3.7. Step 3: Develop Relationships Between
Stormwater Managers, Land Use Planners,
and Other Officials
If land use is to effectively become the "first BMP" for a
stormwater program, it is imperative that stormwater
managers form closer working relationships with
Land use planners
• Transportation planners
School officials
Parks and recreation staff
Public facility engineers
• Emergency management officials
Other local officials
In many jurisdictions, the stormwater managers might
have limited interaction with other municipal staff
who have an impact on the stormwater program.
The stormwater manager is likely housed within a
public works or engineering department. If he or she
is engaged in site plan review, the main focus is at
the site scale. The stormwater manager might also
work on capital projects involving drainage or other
infrastructure.
Meanwhile, land use planners are customarily located
in planning and community development depart-
ments. They engage most closely with zoning issues,
such as setbacks and parking requirements, and they
are also responsible for developing and revising the
community's land use and comprehensive plans. They
might also be involved in community-wide issues like
economic development, housing, and transportation.
A more effective approach would promote integration
across departments and professions, with the compre-
hensive plan being one of the primary mechanisms for
working together. This integration would encourage
more involvement on stormwater issues early in the
planning process. For example, stormwater managers
could be involved in the following areas:
• Land use. Stormwater managers might be
called upon to estimate the stormwater and
flooding impacts of growth alternatives, to
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point out opportunities to use low-impact
and redevelopment alternatives, and to offer
suggestions on which areas of land might be
best suited for handling stormwater. In rural and
suburbanizing areas, stormwater managers might
be asked to assess various build-out scenarios for
future growth and watershed management.
Redevelopment. Because redevelopment is
commonly more complex than new development,
many comprehensive plans attempt to reduce
barriers to redevelopment such as the limited space
for stormwater BMPs at many urban redevelopment
sites. Stormwater departments might be asked
to design district-wide or shared facilities and/or
tailored site-level BMPs suited to ultra-urban
settings.
• Transportation. Transportation plans can be
coordinated with stormwater by considering
linear transportation projects within the context
of watersheds and surrounding development.
Sometimes, stormwater strategies can serve both
transportation and development needs, and
transportation projects might also be able to provide
land or mitigation funds for protected or restored
natural resources areas. Stormwater managers
might also want to engage transportation engineers
on innovative stormwater techniques that can be
incorporated into the road section or right-of-way.
• Economic development. The funding of stormwater
and flood control projects might provide a
strong economic incentive for development
and redevelopment decisions. Stormwater
managers might be asked to work with economic
development staff to see where improvements
meet water and business development needs.
• Parks and open space. Stormwater managers might
be asked to identify parcels with high value for
stormwater management. In urban areas, these
parcels might need to serve several purposes, so
stormwater programs could be called upon to work
with parks, recreation, habitat, or water supply
organizations.
Table 3.5 describes several mechanisms to build better
relationships between stormwater managers, land use
planners, and other local officials.
Table 3.5. Tips for Building Relationships Between Stormwater Managers, Land Use Planners, and Other Local
Officials
Include both land use planners and stormwater managers in pre-concept and/or pre-application meetings for potential
development projects.
Use local government sites (e.g., schools, regional parks, office buildings, public works yards) as demonstration sites for
innovative stormwater management. Form a team that includes land use planners, stormwater managers, parks and school
officials, and others to work out the details.
Include stormwater managers in the comprehensive plan process so that overall watershed and stormwater goals can be
incorporated.
Make sure that both land use planners and stormwater managers are involved in utility and transportation master planning.
Involve stormwater managers in economic development planning, especially for enterprise zones. Main Street projects, and
other projects that involve infill and redevelopment. Encourage stormwater managers to develop efficient watershed-based
solutions for these plans.
Develop cross-training and joint activities that allow land use planners, stormwater managers, and transportation, utility, and
capital project planners to explore how various land use/stormwater processes can be better integrated.
For staff training, bring in speakers who are knowledgeable about stormwater management. Alternatively, encourage land use
planners, stormwater managers, and other local officials to attend training on this topic as a team.
Managing Stormwater in Your Community
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
3.8. Step 4: Use Watersheds as Organizing
Units for the Linked Stormwater/Land Use
Program
Another critical tool for linking stormwater with land
use is to consider land use policies in a watershed
context. Each watershed is unique and has its own
challenges, including:
Important local resources, such as drinking water
supplies, recreational uses, and sensitive features,
such as wetlands, cold-water fisheries, and coastal
bays
• Waterbodies listed as "impaired" on state Total
Maximum Daily Load (TMDL) lists
• Streams and waterbodies that are currently healthy;
future actions should ensure that they stay that way.
Streams and waterbodies that are currently
degraded, characterized by channel erosion and/
or flooding, and/or have existing water quality
problems; future actions should aim to restore
watershed functions where feasible
Watersheds that lie completely within a single
jurisdiction versus those that cross one or more
jurisdictional boundaries
There is no one-size-fits-all approach for integrating
stormwater, land use, and watersheds. Table 3.6
outlines various regulatory, site design, and policy
strategies that can help with this integration.
Tables 3.7 and 3.8 synthesize the strategies presented
in Table 3.6 into a management framework and pres-
ent a menu of options to consider. These tables list
recommended strategies based on both watershed
(Table 3.7) and land use (Table 3.8) characteristics.
The tables also list other approaches that should be
scrutinized because they might run counter to overall
stormwater and land use goals.
Table 3.6. Regulatory and Site Design/Policy Strategies to Integrate Stormwater, Land Use, and Watersheds
Regulatory Tools
Overlay zoning. Overlay zoning is a technique to "overlay" more protective standards over land with existing zoning. This procedure
can be helpful to stormwater managers who need special protection in a discrete area within the watershed. Examples are drinking
water supply watersheds, wellhead protection areas, areas subject to flooding, and watersheds for critical resources, such as wetlands
and special recreational areas. The overlay zone typically designates allowable land uses and performance standards (see below).
Special use permits. In zoning codes, there are often two lists—allowable uses and uses allowed by special use permit. Stormwater
managers might want to explore the use of special use permits to apply BMPs for certain uses (e.g., stormwater hotspots, direct
discharges to wetlands).
Performance standards. Performance standards are usually associated with particular land use categories, and they can also be tied
to special use permits, overlay zoning, and/or rezoning applications. Examples of performance standards are minimizing clearing
and grading, minimizing creation of new impervious surfaces, tree preservation or canopy targets, protection of riparian buffers,
and septic system location and design.
Special stormwater criteria. Special stormwater criteria would likely reside in the stormwater ordinance and/or design manual.
These are criteria that are specifically tailored to discharges to sensitive receiving waters. Examples would be temperature control
for trout streams, more aggressive nutrient management for drinking water supplies and wetlands, groundwater protection criteria
for wellhead protection areas, special detention criteria for flood-prone areas, and pollution prevention measures for stormwater
hotspots. (See Chapter 4 for more detail on special stormwater criteria.)
Site Design and Policy Tools
Compact development. Compact development seeks to meet a certain level of development intensity on a small footprint.
Communities might be seeking this type of design to support walkability, transit station access, reduced infrastructure costs, or
for water resource protection. Compact designs can be used in any development setting from ultra-urban retrofits to rural village
centers.
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
Table 3.6. Regulatory and Site Design/Policy Strategies to Integrate Stormwater, Land Use, and Watersheds
(continued)
Site Design and Policy Tools
Street design. Many state departments of transportation are issuing "context-sensitive" alternatives for street design. These designs
include narrow streets and consider multiple transportation modes. For transportation planners, the narrow streets are aimed at
slower speeds and neighborhood design models. Stormwater managers thus have overlapping interests in better street design.
Utility planning. The rational and planned expansion of public water, sewer, and other utilities is critical for both land use planning
and Stormwater management. Utility extensions will likely encourage future growth at higher densities. Utility extensions should
be planned for areas designated for infill, redevelopment, and future growth. On the other hand, utility restrictions should be
considered for sensitive watersheds.
Mixed-use development. Highly separated uses (e.g., retail, schools, housing, jobs) are implicated in highly dispersed development.
A high degree of automobile-supporting infrastructure, which can be over 50% of development-related imperviousness, is "built
in" because walking and other modes of travel cannot be effectively supported. Bringing the uses closer together can lower
the number and length of auto trips or support trip substitution. Less roadway and parking can translate into a lowered overall
development footprint.
Infill. Communities are increasingly interested in targeting development to areas where the surrounding land is already developed
and served by public utilities. An example is developing housing surrounding a mall or office park. This "infilling" can satisfy a high
degree of development demand in an efficient manner.
Redevelopment. One of the strongest watershed strategies is reusing (and improving) vacant or underused sites that a re already
under impervious cover. This is not only an urban strategy, but can work for abandoned sites in rural areas as well. Programs such as
downtown revitalization. Main Street programs, and brownfield redevelopment programs support these efforts.
Conservation development. Conservation development is a strategy that can work in various development contexts (e.g., urban,
suburban) to coordinate and conserve open space. For Stormwater, a particular emphasis may be placed on riparian buffers, forest
protection, and open-space areas that capture and disperse runoff.
Purchase andtransfer ofdevelopment rights (PDR, TDR). PDR programs purchase development rights from landowners and are
particularly targeted to areas or watersheds where rural character and natural resources should be protected. TDR programs set
up development rights markets whereby some landowners (in rural or sensitive watersheds) can sell their development rights to
landowners in areas where growth, infill, and redevelopment are encouraged.
Fee-in-lieu programs for Stormwater. In certain areas, Stormwater management goals cannot be met solely with on-site Stormwater
BMPs. Watershed-based approaches are needed to address issues that extend beyond the site boundary. Examples would be areas
with existing flooding or drainage problems, impaired watersheds, and watersheds with streambank erosion problems. In these
cases, a fee-in-lieu payment or offset fee can be collected from developers to partially offset full on-site compliance. The local
Stormwater program then uses the accumulated fees to conduct needed watershed repairs and improvements. (See Chapter 4 for
more information on watershed-based Stormwater management approaches and criteria.)
Managing Stormwater in Your Community
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
Table 3.7. Integrated Stormwater and Land Use Strategies Based on Watershed Characteristics
Watershed
Characteristics
Integrated Strategies to Consider3
Approaches That May NOT
Be Appropriate
Special receiving waters:
drinking water, trout
streams, wetlands, etc.
Overlay zoning and performance standards
Conservation development
Special Stormwater criteria
Low-impact development
>• Purchase of Development Rights (PDR)
>• "Sending" area for Transfer of Development
Rights (TDR)
Large-lot zoning (disperses and spreads
out development impacts)
Relying solely on Stormwater ponds and
basins
Urban road sections
Utility and transportation expansions
Existing flooding
problems
Overlay zoning and performance standards
Special Stormwater criteria
Low-impact development
Street design
Fee-in-lieu program
Relying solely on site-by-site Stormwater
approaches that are not coordinated at
watershed scale
Wide roads, urban road sections
Impaired streams
(303(d) listed) or other
water quality problems
Special Stormwater criteria
Special use permits for certain uses
(e.g., hotspots)
>• Performance standards
Low-impact development
Conservation development
>• Relying solely on Stormwater ponds and
basins
Urban road sections
a See Table 3.6 for brief descriptions of the various strategies.
Table 3.8. Integrated Stormwater and Land Use Strategies Based on Land Use Characteristics
Land Use
Characteristics
Urban core: incentive/
enterprise zones,
redevelopment
zones, town centers,
brownfields
Urbanizing: designated
for future growth,
planned utility and/
or transportation
expansions
Rural: desire to maintain
rural character and
working farms, special
or unique natural
resources
Integrated Strategies to Consider3
>• Waivers and variances
>• Fee-in-lieu program for watershed projects
>• Compact and mixed-use development
>• Infill and redevelopment incentives
>• Low-impact development
>• "Receiving" area forTransfer of
Development Rights (TDR)
>• Fee-in-lieu program for watershed projects
>• Compact and mixed-use development
>• Conservation development
>• Low-impact development
>• Street design. Green Streets
>• Good stream buffering
>• Performance standards
>• "Receiving" area forTDR
>• Conservation development
>• Aggressive stream buffering
>• Performance standards
>• Special Stormwater criteria
>• Low-impact development
*• "Sending" areas for TDR
Approaches That May NOT
Be Appropriate
>• Impervious cover limits
>• Aggressive open space requirements
>• Large-lot zoning
>• Ambitious on-site infiltration
requirements
>• Large-lot zoning
>• Conventional development standards
that disperse the development footprint
>• Use of waivers and variances
>• Urban road sections
>• Utility and transportation expansions
>• Conventional development standards
1 See Table 3.6 for brief descriptions of the various strategies.
Managing Stormwater in Your Community
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
3.9 Considering Climate Change in the
Stormwater and Land Use Program
Many of the assumptions that Stormwater managers
use for runoff and storm system design might become
outdated if climate change predictions become a real-
ity (Funkhouser, 2007; Oberts, 2007). For example,
such Stormwater mainstays as the "design storm" will
need to be scrutinized to ensure that future storm-
water designs are responsive to changing climate
conditions.
Integrated Stormwater and land use solutions have
an important role to play in this challenging task. It is
safe to assume that we cannot rely solely on "hard"
or technological solutions to deal with such climate
change scenarios as more frequent flooding and more
prolonged droughts. Solutions more rooted in land
use planning will have to play a role. These will include
improved floodplain management, urban Stormwa-
ter forestry, and strategies to promote more efficient
development layouts—to promote greater efficiency
in Stormwater management, water conservation, and
energy consumption.
EPA's climate change Web site (http://www.epa.gov/
climatechange) includes comprehensive information
on the many different issues affecting climate change.
EPA's National Water Program is developing a strategy
on climate change that describes how best to meet
clean water and safe drinking water goals in the con-
text of a changing climate (http://www.epa.gov/
water/climatechange).
Stormwater managers and land use planners can work
together on important adaptations to climate change.
Some of these adaptations will need to respond to
changing hydrologic realities (hydrologic adaptations);
others will have to be coordinated with broader policy
initiatives to respond to climate change (policy adap-
tations). Table 3.9 provides several conceptual ideas
for how integrated Stormwater and land use tools can
help adapt to both the natural resources and policy
outcomes of climate change.
3.10. Relating Stormwater and Land Use to This
Guidance Manual
Certainly, there are challenges to integrating Stormwa-
ter and land use planning. They include coordination
across multiple departments, coordination among
multiple permitted agencies and jurisdictions, and
political forces that compel land use decisions away
from a watershed approach. However, the value of
managing the landscape by linking land use practices
to water quality protection is that long-term solu-
tions that reduce Stormwater impacts throughout the
region are created.
As local Stormwater managers endeavor to build
programs that are responsive to local conditions,
state permit requirements, and existing practices,
they should keep land use in mind as the "first BMP."
Perhaps the simplest step is to forge stronger working
relationships with land use planners and other local
officials. This chapter can be a discussion starter for
Stormwater managers and land use planners as they
begin important deliberations on how integration can
and should take place at the local level.
Managing Stormwater in Your Community
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
Table 3.9. Climate Change and Conceptual Land Use/Stormwater Adaptations
Hydrologic Adaptations
More frequent
flooding
Remap floodplains based on "new" frequent and infrequent events.
Adopt stringent regulations to restrict development within floodplains.
>• Develop mitigation programs to remove susceptible structures from floodplains.
Conduct more frequent cleaning of storm sewer infrastructure in urban areas to maintain hydraulic
capacity.
Ensure that all new development has overland relief in case of system failure.
>• Model storm sewer infrastructure using new climate scenarios and coordinate with emergency
response plans.
More prolonged
droughts
Extend rainwater harvesting beyond individual rooftop scale to neighborhood/community scale.
Use stormwater as a resource.
>• Develop drought-resistant planting plans for BMPs and municipal landscaping.
>• Promote urban forestry and forest protection to promote shade and retention of moisture.
Incorporate groundwater recharge into all BMPs where safe and feasible.
Increased
temperature of
runoff
>• Include trees and other plantings in BMP designs.
Develop methods to reduce "straight-piping" of runoff to streams; use disconnection methods to
direct runoff to buffers, planted areas, pervious parking, forested BMPs, etc.
Develop impervious limits and minimum tree canopy requirements for special temperature-
sensitive receiving waters (e.g., high-value trout streams).
More combined
sewer overflows
Incorporate volume-reduction measures across landscape: individual homes, streets, businesses,
etc. These can include rain gardens, rainwater harvesting, dry wells, etc.
Strategically locate and use open-space areas for runoff capture to reduce flows into system.
Policy Adaptations
Reduce carbon
emissions
Promote compact development and reduce vehicle trips/miles.
Provide stormwater incentives for redevelopment close to urban centers and more stringent
requirements for new (greenfields) development that requires more driving.
>• Provide stormwater credits for transit and bicycle facilities at development sites.
Consider the embodied energy of BMP materials and installation (e.g., plastic/wood components,
land cleared for BMPs) as a BMP selection criterion.
Increase carbon
sequestration
>• Use urban forestry as a stormwater BMP.
>• Incorporate trees into all or most new BMPs.
>• Design integrated stormwater/carbon sequestration facilities; incorporate planting maintenance
plans that maximize carbon uptake.
Increase clean,
renewable energy
sources
Incorporate small-scale power generation into some BMP and storm sewer designs that have
adequate head.
Colocate neighborhood-scale stormwater BMPs with solar, wind, and other renewable-energy
facilities.
Managing Stormwater in Your Community
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Chapter 3: Land Use Planning as the First Bmp: Linking Stormwater to Land Use
Managing Stormwater in Your Community
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Chapfc
Developing a Stormwater
Management Approach
and Criteria
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 3
Linking Stormwater to
Land Use
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Stormwater
Manual Builder
Companion Tools for Chapter 4
Download Post-Construction Tools at:
www.cwp.org/postconstruction
Managing Stormwater in Your Community
What's In This Chapter
A recommended Stormwater management approach
i Developing Stormwater management criteria
Natural resources inventory
Runoff reduction
Water quality
Channel protection
Flood control
Redevelopment
Developing a rainfall frequency spectrum
• Special Stormwater criteria for sensitive receiving
waters
A watershed-based Stormwater approach
-------
Chapter 4: Developing a Stormwater Management Approach and Criteria
4.1. Clarifying the Stormwater Management
Approach
Chapter 2 described some fundamental steps to plan a
post-construction Stormwater program, and Chapter 3
described a holistic approach for integrating Stormwa-
ter with land use planning.
The next steps in program development are to put all
the pieces in place to have an operational program.
These include:
Adopt or amend a Stormwater ordinance.
Develop, amend, or reference a Stormwater
guidance manual.
Create a Stormwater plan review process.
Inspect permanent Stormwater BMPs during initial
installation and construction.
• Develop a maintenance program.
• Track, evaluate, and report on the program.
Before jumping into these tasks, it is important to
clarify the overall Stormwater management approach
that the program will take. Stormwater management
has seen many innovations in recent years. Each com-
munity should evaluate various approaches and figure
out the best way to move the program forward and
protect receiving waters.
This chapter outlines some basic techniques to:
Select a Stormwater management approach that
will guide the program (Section 4.2)
• Develop Stormwater management criteria to be
used in ordinances and design guidance
(Sections 4.3 and 4.7)
Use rainfall data to link Stormwater criteria to
particular rainfall events (Section 4.4)
Add criteria for special receiving waters
(Sections 4.5 and 4.7)
• Consider incorporating a watershed-based
approach for Stormwater (Section 4.6)
Table 4.1 outlines some critical decisions that storm-
water managers should explore to develop a local
Stormwater approach.
4.2. A Recommended Stormwater Management
Approach
Most Stormwater programs rely heavily on conven-
tional end-of-pipe treatment of Stormwater. Although
these BMPs are a critical component of Stormwater
management, there is a broader range of options to
consider. Many opportunities are missed by simply
collecting and treating runoff after it has already
been generated. In fact, there are many techniques to
reduce Stormwater impacts at the front end through
site design and source control methods.
In this respect, there is a recommended hierarchy of
Stormwater treatment methods:
• First, reduce runoff through design: Use
site planning and design techniques to reduce
impervious cover, disturbed soils, and Stormwater
impacts. Use techniques such as conservation
design, protecting critical open space and natural
drainage features, and disconnecting a site's
impervious cover to reduce the generation of
Stormwater runoff. At a broader community and
watershed scale, this might also mean encouraging
infill and development within targeted zones while
preserving open spaces and functional landscapes
beyond those areas (see Table 4.2).
• Second, reduce pollutants carried by runoff: Use
source control and pollution prevention practices
to reduce the exposure of pollutants to rainfall
and runoff. Examples include keeping impervious
surfaces clean, educating homeowners on proper
yard waste and fertilization methods, handling
and storing chemicals properly, and collecting and
recycling hazardous chemicals (see Table 4.3).
• Third, capture and treat runoff: Design storm-
water BMPs to collect and treat the Stormwater
that is generated after applying the site design and
source control methods described above. Some
Stormwater collection and treatment can be in
small-scale, distributed practices close to the source
of runoff. Examples include rain gardens, filter strips,
and pervious parking. Site designers should attempt
to blend this approach with more conventional
practices—such as ponds, Stormwater wetlands,
and filters—to come up with the most effective BMP
design (see Table 4.4).
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.1. Critical Decisions to Identify a Stormwater Management Approach
Land Use
What is the best way to integrate Stormwater with land use? Chapter 3 provides a detailed
discussion on this important link.
Site Design
To what extent should the program promote and give credit for good site design practices, such as:
Open space conservation
>• Reduction of impervious surfaces and site disturbance
>• Riparian, wetland,and waterway buffers
Disconnection of impervious surfaces
Site reforestation
>• Desirable infill and redevelopment
Although many Stormwater programs would like to see these types of practices, fewer provide the
programmatic and regulatory incentives to make it happen.
Source Controls and
Pollution Prevention
While the conventional approach to Stormwater management is to collect and treat runoff at some
point downstream from the source, a more comprehensive approach is to reduce or eliminate
the exposure of pollutants to runoff in the first place. Examples of source control and pollution
prevention practices include:
Street sweeping
Pet waste education programs
>• Household hazardous waste collection
Spill containment and response
A local program must decide how to incorporate these practices.
Conventional Stormwater
BMPs
Some Stormwater BMPs, such as ponds and basins, have been around fora long time. The local
program must determine how to promote a better mixture of conventional and innovative practices
(see below).
Low-Impact Development
and Green Infrastructure
BMPs
Many innovative practices can be distributed across the site and can do a good job of reducing
runoff volumes and overall Stormwater impacts. However, appropriate Stormwater criteria and
credits must be in place in order for developers and site designers to use the innovative practices.
Also, the local program must have the administrative, plan review, inspection, and maintenance
capabilities to ensure that conventional and innovative practices are properly designed, installed,
and maintained
Special Receiving Waters
Not all watersheds are created equal. Some watersheds might require some customized approaches
to Stormwater management. Examples include:
>• Nutrient control for lakes, water supply reservoirs, and wetlands
Pollution prevention for groundwater supply areas
Additional Stormwater controls for impaired waters
The community must identify special receiving waters and address these unique conditions in the
Stormwater criteria.
Site-by-Site or
Watershed-Based
Most communities address Stormwater on a site-by-site basis as development takes place. However,
some programs have found that they can better address watershed impacts and promote more
cost-effective BMPs with a watershed approach. Programs that want to pursue this approach should
create the planning, regulatory, and financial tools to make it work.
Stormwater Management
Criteria
All the decisions listed above in this table must be distilled into understandable and achievable
criteria that are established in the Stormwater ordinance and, ideally, discussed in detail in a
Stormwater guidance manual.
Traditionally, most Stormwater programs had criteria for flood control. However, today's programs
are expected to also address water quality, downstream channel protection, and perhaps runoff
reduction, groundwater recharge, and natural resources protection.
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.2. Hierarchy of Stormwater BMP Selection—Site Planning and Design
1. Site Planning and Design
First, reduce runoff through design:
Plan the site to reduce Stormwater runoff volume and impacts through design techniques.
Preservation and/or Restoration of Undisturbed
Natural Areas
Preservation of Riparian Buffers, Floodplains, and
Shorelines
Preservation of Steep Slopes
Preservation of Porous and Erodible Soils
Preservation of Existing Topography
Prairie/Meadow Restoration
Site Reforestation
Soil Amendments/Soil Rejuvenation
Avoidance of Sensitive Areas
Reduced Clearing and Grading Limits
Conservation Development
Reduced Roadway Lengths and Widths
Shorter or Shared Driveways
Shared Parking
Reduced Building Footprints
Reduced Parking Lot Footprints
Reduced Setbacks and Frontages
Use of Fewer or Alternative Cul-de-Sacs
Use of Natural Drainageways
Incentives for Infill and Redevelopment Within
Targeted Development Zones
See Tool 4: Codes and Ordinance Worksheet for guidance on modifying local development codes to allow these practices.
Also see:
Better Site Design: A Handbook for Changing Development Rules in Your Community, Center for Watershed Protection, Inc.
www.cwp.org > Online Store > Better Site Design
Using Smart Growth Techniques as Stormwater Best Management Practices, U.S. EPA.
http://www.epa.gov/smartgrowth/stormwater.htm
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.3. Hierarchy of Stormwater BMP Selection—Source Control Practices
2. Source Control and Pollution Prevention Practices
Second, reduce pollutants carried by runoff:
Reduce exposure of pollutants to rainfall and runoff through source control and pollution
prevention practices.
Residential
Natural Landscaping
Tree Planting
Yard Waste
Composting
Septic System
Maintenance
Driveway Sweeping
Street Sweeping
Household Hazardous
Waste Collection
Programs
Car Fluid Collection
and Recycling
Programs
Downspout
Disconnection
Pet Waste Pickup
Storm Drain Marking
Nonresidential
Covered Loading Areas
Covered Fueling Areas
Covered Vehicle
Storage Areas
Storm Drain
Disconnection
Downspout
Disconnection
Street Sweeping
Covered Dumpsters
Covered Materials
Storage Areas
Secondary
Containment
Structures
Spill Response Plans
Signage
Employee Training
See Manual 8, Pollution Source Control Practices, Urban Subwatershed Restoration Manual Series,
Center for Watershed Protection, Inc.
www.cwp.org> Online Store > Subwatershed Restoration Manuals
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.4. Hierarchy of Stormwater BMP Selection—Stormwater Collection and Treatment
3. Stormwater Collection and Treatment
Third, capture and treat runoff:
Collect and treat Stormwater runoff through small-scale distributed practices (close to the source
of runoff) and other structural BMPs.
Small-Scale
Distributed Practices
Downspout
Disconnection
Impervious Cover
Disconnection
Rainwater Harvesting
Rain Gardens
Small Bioretention
Areas
Dry Wells
French Drains
Green Rooftops
Porous and Pervious
Pavement
Stormwater Planters
Vegetated Filter Strips
Vegetated
Channels/Swales
Other
Structural BMPs
Infiltration Devices
Larger Bioretention
Areas
Extended Detention
Ponds
Wet Ponds
Constructed
Stormwater Wetlands
Engineered Swales
Filtering Practices
Manufactured BMPs
See Tool 5: Manual Builder for guidance on good design references.
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
The local program should strive to provide standards
and guidelines for all three categories of stormwater
treatment. Tables 4.2 through 4.4 provide candidate
BMPs and resources for each category. Tool 5: Manual
Builder provides links to design manuals across the
country that provide good examples.
4.3. Developing Stormwater Management
Criteria
Stormwater management criteria are the technical core
of a stormwater ordinance (Chapter 5) and a major
focus of stormwater guidance manuals (Chapter 6).
They establish the design objectives for BMPs, and
they will influence directly the types and sizes of these
practices.
The list below describes the technical stormwater
criteria that are adopted by stormwater programs
around the country within ordinances and design
guidance. Tool 3: Model Stormwater Ordinance
contains model language for each of these criteria. It
is important to note that the Phase I and II MS4 permit
program is concerned largely with criteria that help
meet water quality standards (1 through 4 below).
Flood control (5) is historically a more common and
locally applied criterion.
1 - Natural Resources Inventory (NRI): identify the
site's critical natural features and drainage patterns
early in the site planning process.
2 - Recharge and/or Runoff Reduction (RR): main-
tain groundwater recharge rates and/or reduce post-
development runoff volume by a set amount.
3 - Water Quality Volume (WQV): capture and treat
runoff from the water quality storm to remove certain
target pollutants.
4 - Channel Protection (CP): design the stormwater
system so that conveyances and outfalls are stable and
will not erode downstream channels or cause damage
to downstream habitats.
5 - Flood Control (FC): control peak rates to reduce
downstream flooding. The criterion can have two
components:
Overbank (Minor Storm) Flood Control: provide
storage for storm events that might cause routine
flooding to downstream property, conveyance
systems, and drainage infrastructure.
Extreme (Major Storm) Flood Control: provide
storage for infrequent but large storm events that
might cause downstream flooding and damage
and/or enlarge the boundaries of the floodplain.
6 - Redevelopment: provide flexibility for redevelop-
ment sites where stormwater compliance might be
more difficult and can be met through a variety of
strategies. A redevelopment criterion provides flexibil-
ity in meeting criteria 1 through 5 above where a site
meets the definition of redevelopment.
A unified approach is the most effective way to
develop stormwater management criteria and pres-
ent them within the local ordinance and/or guidance
manual. The goal of a unified framework is to develop
a consistent approach for designing BMPs that can:
Perform effectively: Manage the range of stormwater
flows and volumes that will actually mitigate local
stormwater problems; protect public health and
safety; and reduce flood, water quality, and channel
erosion hazards.
Perform efficiently: Manage just enough runoff volume
to address the problems but not over-control them.
Providing more stormwater storage is not always
better, and it can greatly increase construction costs
and consume valuable land.
Be simple to administer: Be understandable, relatively
easy to calculate with current hydrologic models,
and workable over a range of development
conditions and intensities. In addition, stormwater
management criteria should be clear and straight-
forward, and backed up by the local stormwater
ordinance, to avoid needless disputes between
design engineers and plan reviewers when they are
applied to development sites.
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Promote multipurpose, integrated stormwater design:
Allow for flexible and creative design to integrate
into community aesthetics, enhance property
values, and serve multiple purposes (such as storm-
water and recreation).
Be flexible to respond to special site conditions:
Define certain site conditions or development
scenarios where individual stormwater sizing criteria
may be relaxed or waived when they are clearly
inappropriate or infeasible.
Figure 4.1 graphically portrays a unified, or nested,
approach for the six stormwater management criteria
listed above.
The "nesting" of the criteria portrayed in Figure 4.1
can best be understood by considering the overall
volume of runoff generated by a site. Each of the
stormwater management criteria relates to a certain
volume of the overall runoff volume to be managed.
For instance, runoff reduction and water quality
management usually entail capturing a smaller volume
of water than channel protection and flood control.
However, the volume of runoff that is infiltrated,
captured, and/or treated in a water quality BMP can
reduce the overall volume that remains to be treated
for downstream channel protection and flood control.
Put another way, a site that maximizes runoff reduction
through infiltration, soil absorption, and capture and
reuse can reduce the size and possibly the need for
larger, structural storage devices like pond and basins.
The criteria outlined in this section should be
considered as candidate (or potential) criteria fora
local program. The criteria should be adapted to local
conditions (soils, geology, water table, etc.), the level of
program sophistication, and local goals and concerns.
Table 4.5 provides some guidance for adapting the
criteria to unique conditions, such as good (or poor)
WQV Not Managed by RR
CP Volume Not Managed by RR+WQv
•
gedbyRR + WQv + CP
Flood Control Volume/Peak Discharge Not Ma
Figure 4.1. Graphic representation of the nested approach to stormwater management criteria
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.5. Suggested Adaptations for Stormwater Management Criteria in Different Settings
Variable Settings
for Stormwater
Management
Possible/Conceptual Adaptations to Stormwater Criteria
Generally good soils for
infiltration; few constraints,
such as shallow bedrock
>• Apply criterion 1 (natural resources) as a planning and site design tool.
Collapse criteria 2 through 4 (runoff reduction, water quality, and channel protection) into a
single criterion for Runoff Reduction.
Define the Runoff Reduction Volume as the 1-year, 24-hour rainfall depth, or a similar criterion
adopted by the local program.
>• Each site should maximize runoff reduction through infiltration, canopy interception,
evaporation, transpiration, and/or rainwater harvesting.
>• Any fraction of the Runoff Reduction Volume that cannot feasibly be eliminated from site
runoff should be treated through extended detention3 or extended filtration.b
Allow Runoff Reduction waivers for sites where it is not feasible. Require that the full Runoff
Reduction Volume be treated in an applicable water quality BMP.
>• Apply criterion 5 (flood control) where it is needed to protect downstream property,
conveyance systems, and infrastructure. If applicable, allow a reduction in the required volume
forall or part of volume reduced through Runoff Reduction BMPs.
Arid climates
Generally follow the guidance above for areas with good infiltration potential; rely on a
balanced approach of infiltration and evaporation. Provide waivers where infiltration is not
feasible or advisable.
Select BMPs based on criteria including ability to reduce sediment loads.
Apply criterion 5 (flood control), ensuring that large, damaging storm events have safe
conveyance to an adequate downstream system.
Generally poor soils for
infiltration; possible other
constraints such as high
water table or shallow
bedrock
>• Apply criterion 1 (natural resources) as a planning and site design tool.
Apply criterion 2 (runoff reduction) to establish a minimum, or modest, level of performance
for runoff reduction, such as reducing the first 0.5 inch of runoff from the post-development
condition (or an appropriate local standard). In some locations, infiltration might not be a
feasible runoff reduction method.
>• Allow waivers for sites where runoff reduction can be proven to be infeasible (the volume
should still be required to be treated for water quality; see below).
>• Apply criterion 3 (water quality) to a prescribed "water quality volume." This should be the 90th
percentile rainfall event (see Table 4.9) or an applicable local standard.
>• Apply criteria 4 and 5 (channel protection, flood control) where they are needed to protect
downstream channels, property, conveyance systems, and infrastructure. If applicable, allow
a reduction in the required volume for all or part of volume reduced through runoff reduction
and water quality BMPs.
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.5. Suggested Adaptations for Stormwater Management Criteria in Different Settings (continued)
Variable Settings
for Stormwater
Management
Karst
Watersheds with an
extensive existing ditch
system (past agricultural
practices)
Redevelopment
Possible/Conceptual to Adapt Stormwater Criteria
>• Combine criteria 1 (natural resources) and 2 (runoff reduction) as a planning and site design
tool. Include identification of sinkholes and karst features in early site layout, with possible
setbacks from these features. Promote infiltration across broad landscape areas (such as open
space, swales, and soil amendment) instead of concentrating site runoff to small, engineered
infiltration BMPs. Provide credits for sites that do a good job with site design.
>• Apply criterion 3 (water quality) to a prescribed "water quality volume." This should be the 90th
percentile rainfall event (see Table 4.9) or an applicable local standard. Require pretreatment
and/or lining for BMPs sited on karst with shallow soil cover.
>• Apply criteria 4 (channel protection). Develop special provisions for discharges to sinkholes and
areas with no downstream surface channel to handle increased site runoff.
>• Apply criterion 5 (flood control) where it is needed to protect downstream property,
conveyance systems, and infrastructure. If applicable, allow a reduction in the required volume
for a II or part of volume reduce through site design, water quality, and channel protection
BMPs.
>• Adapt criterion 1 (natural resources) to include ditch restoration and/or naturalization as
a possible post-construction BMP. Practices can include adding sinuosity, restoring prior-
converted wetlands, and streambankand riparian planting.
>• See other cases in this table for options for criteria 2 and 3.
>• Criteria 4 and 5 (channel protection, flood control) should consider ditch capacity. As with
criterion 1, ditch restoration can play a role in meeting channel protection, and possibly flood
control, objectives.
>• Allow flexible compliance strategies for all criteria based on specific program goals and site
conditions.
a Extended detention includes Stormwater BMPs that capture runoff and release it slowly over an extended period, usually 12 to 24 hours. The
goal is to maintain a flow rate and velocity that do not damage downstream channels.
b Extended filtration includes Stormwater BMPs that capture runoff and delay its release until after most of the site runoff fora given storm has
passed to the downstream system. Examples are bioretention and water quality swales with underdrains that delay delivery of Stormwater
from small sites to the downstream system by six hours or more.
soils for infiltration, karst, arid climates, and locations
with extensive ditch systems. The categories in the
table are fluid in that more than one category may
apply to a given community, and not every possible
scenario is identified. Also, the adaptations in the table
are for illustrative purposes; a Stormwater manager
must choose the most appropriate criteria and
adaptations for the local program.
Tables 4.7 through 4.12 at the end of this chapter
provide more detail for each of the six Stormwater
management criteria. These tables are most useful for
assembling language and standards for Stormwater
ordinances and guidance manuals (again, local adap-
tations are strongly encouraged). The tables provide
potential standards and candidate BMPs that can be
used to meet each of the criteria. Finally, the tables
provide links to programs, design manuals, or existing
resources that provide examples of the criteria. (Tool 5:
Manual Builder Tool contains additional examples.)
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Chapter 4: Developing a Stormwater Management Approach and Criteria
4.4. Developing a Rainfall Frequency Spectrum
Rainfall Frequency Spectrum (RFS) curves (which are
also known as "rainfall distribution plots") are useful
tools to assist stormwater managers with the develop-
ment of stormwater management criteria, particularly
the criteria that relate to smaller storm events (runoff
reduction or recharge, water quality).
The RFS helps to link the various criteria with particular
rainfall events. For instance, if the local water qual-
ity criteria relate to treatment of runoff from the 90th
percentile storm event, an RFS curve will help establish
this particular rainfall depth. Figure 4.2 provides guid-
ance on creating RFS curves, and Table 4.6 provides
rainfall depth frequency statistics for cities across the
United States.
4.5. Special Stormwater Criteria for Sensitive
Receiving Waters
One of the unique development situations for which
basic stormwater management criteria may be modi-
fied is when sensitive receiving waters must be pro-
tected. This recognizes the fact that not all stormwater
discharges are created equal, and that certain water-
sheds require a customized approach.
There has been a trend in recent years to develop
special stormwater criteria to protect sensitive water
resources (CWP, 2006). Special stormwater design
criteria have been created by state and local storm-
water management programs to protect each of the
following:
• Lakes and water supply reservoirs
• Cold water fisheries (trout and salmon streams)
Groundwater
Wetlands
• Impaired waters
Special stormwater design criteria typically make use
of one or more of the following strategies:
• Enhancing stormwater BMP design features to
provide a higher level of pollutant removal
(e.g., sizing, internal geometry, vegetation,
pretreatment, multiple treatment methods, etc.).
Adding runoff reduction, groundwater recharge,
and/or downstream analysis to provide greater
protection from streambank erosion.
Requiring the use of certain stormwater BMPs to
provide additional protection for sensitive receiving
waters (e.g., requiring specific stormwater BMPs at
known stormwater hotspots to reduce pollutant
loads).
• Instituting special design criteria for individual
stormwater BMPs to enhance performance or
diminish downstream impacts (e.g., for cold water
fisheries, to mitigate stream warming caused by
stormwater ponds).
Establishing restrictions on where stormwater
BMPs may be located at a site and where they may
discharge.
Additional information on each of the special
stormwater design criteria is presented in Tables 4.13
through 4.17 at the end of this chapter.
4.6. A Watershed-Based Stormwater Approach
An emerging trend for stormwater programs is to
move beyond the site-by-site design and installation
of BMPs. Some programs enhance the site-by-site
approach with a master stormwater plan or watershed-
based plan. Such a plan integrates what is required
at the site level with broader watershed projects to
achieve certain watershed objectives.
For instance, the plan might specify stream and
riparian restoration projects, stormwater retrofits,
impervious disconnection programs, wetland
preservation, subregional BMPs, and/or watershed
outreach activities. A site that is being developed
within the subject watershed might contribute funds,
land, or design support to a watershed project in
lieu of (or, in some cases, as a supplement to) the
installation of on-site BMPs. Figure 4.3 shows several
examples of watershed-based stormwater projects.
The stormwater ordinance must establish the
authority to allow contributions to regional or
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Chapter 4: Developing a Stormwater Management Approach and Criteria
A Rainfall Frequency Spectrum (RFS) is a tool that Stormwater managers should use to analyze and develop local Stormwater
management criteria and to provide the technical foundation for the criteria.
Over the course of a year, many precipitation events occur within a community. Most events are quite small, but a few can
create several inches of rainfall. An RFS illustrates this variation by describing how often, on average, various precipitation
events (adjusted for snowfall) occur during a normal year.
The graph below provides an example of a typical rainfall frequency spectrum and shows the percentage of rainfall events
that are equal to or less than an indicated rainfall depth. As shown, the majority of storm events are relatively small, but there
is a sharp upward inflection point that occurs at about 1 inch of rainfall (90% rainfall event). The 90% rainfall depth is the
recommended standard for the Water Quality Volume (see Table 4.7).
10
9
8
^- 6
o
I
IQ
tc.
1-year, 24-hour storm = 2.4"
Target for Channel Protection (CP)
90% Rainfall Event = 1"
Recommended Water
Quality Volume (WQv)
Maximize Runoff Reduction (RR) for All
Runoff Producing Events Up to the 1 -year,
24-hour storm
10% 20%
30%
40% 50% 60%
Percentile
70%
80% 90% 100%
Rainfall Frequency Spectrum
for Minneapolis-St. Paul, MN
(1971-2000) with several
noteworthy rainfall events
identified (adapted from
MSSC, 2005).
Guidance on creating an RFS is provided below. If a community is large in area or has considerable variation in elevation or
aspect, the RFS analysis should be conducted at multiple stations.
1. Obtain a long-term rainfall record from an adjacent weather station (daily precipitation is fine, but try to obtain at least 30
years of daily record). NOAA has several Web sites with long-term rainfall records (see http://www.nesdis.noaa.gov). Local
airports, universities, water treatment plants, or other facilities might also maintain rainfall records.
2. Edit out small rainfall events than are 0.1 inch or less, as well as snowfall events that do not immediately melt.
3. Using a spreadsheet or simple statistical package, analyze the rainfall time series and develop a frequency distribution that
can be used to determine the percentage of rainfall events less than or equal to a given numerical value (e.g., 0.2,0.5,1.0,
1.5 inches).
4. Construct a curve showing rainfall depth versus frequency, and create a table showing rainfall depth values for 50%, 75%
90%, 95% and 99% frequencies.
5. Use the data to define the Water Quality storm event (90th percentile annual storm rainfall depth). This is the rainfall depth
that should be treated through a combination of Runoff Reduction (Table 4.6) and Water Quality Volume treatment
(Table 4.7).
6. The data can also be used develop criteria for Channel Protection (Table 4.8). The 1-year storm (approximated in some
areas by the 99% rainfall depth) is a good standard for analyzing downstream channel stability.
7. Other regional and national rainfall analysis such as TP-40 (NOAA) or USGS should be used for rainfall depths or intensity
greater than 1 year in return frequency (e.g., 2-, 5-, 10-, 25-, 50-, or 100-year design storm recurrence intervals).
Figure 4.2. Creating a Rainfall Frequency Spectrum (RFS) to assist with development of Stormwater management
criteria
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.6. Rainfall Statistics and Frequency Spectrum Data for Select U.S. Cities
City
Atlanta, GA
Knoxville.TN
New York City, NY
Greensboro, NC
Boston, MA
Baltimore, MD
Buffalo, NY
Washington, DC
Columbus, OH
Kansas City, MO
Seattle, WA
Burlington, VT
Dallas, TX
Austin, TX
Minneapolis, MN
Coeur D'Alene, ID
Sa It Lake City, UT
Denver, CO
Los Angeles, CA
Boise, ID
Phoenix, AZ
Las Vegas, NV
Precipitation
Annual
Inches
50
48
44
43
43
42
41
39
39
38
37
36
35
34
29
26
17
16
13
12
8
4
Daysb
77
85
74
73
76
71
88
67
79
63
90
79
32
49
58
88
44
37
22
38
29
10
Rainfall event: Depth in inches3
50%
0.5
0.4
0.4
--
0.4
0.4
0.3
0.4
0.3
0.4
--
0.3
--
--
0.3
0.2
0.2
--
--
--
--
--
75%
0.9
0.7
0.7
--
0.6
0.8
0.5
0.8
0.6
0.7
--
0.5
--
--
0.6
0.3
0.4
--
--
--
--
--
90%c
1.6
1.2
1.2
1.6
1.2
1.2
0.8
1.2
1.0
1.1
1.3
0.8
1.1
1.4
1.0
0.5
0.6
0.7
1.3
0.5
0.8
0.7
95%
2.1
1.5
1.7
--
1.6
1.6
1.1
1.7
1.3
1.7
1.6
1.1
--
--
1.4
0.7
0.8
--
--
--
--
--
99%d
3.4
2.4
2.7
2.7
2.6
2.5
1.8
2.4
2.1
3.2
1.7
1.7
3.2
3.2
2.4
1.1
1.2
--
--
--
1.1
0.8
Notes: Dashed lines indicate no data available to compute.
a Excludes rainfall depths of 0.1 inch or less.
b Average days per year with measurable precipitation.
c The 90% storm is frequently used to define the water quality volume.
d The 99% storm is an approximation of the 1-year storm in some areas (but is not an exact replication because the statistical analysis
is different).The 1-year, 24-hour storm is frequently used as a design storm for downstream channel protection. The recommended
approach is to conduct an analysis of the runoff generated by the 1 -year, 24-hour storm to derive channel protection criteria.
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Urban Stormwater Retrofits
Rooftop Disconnection Programs
Enhancements to Regional BMPs
Stream and Riparian Restoration
Innovative BMPs at Municipal Facilities
Watershed Outreach Activities
Figure 4.3. Several examples of projects that can be included in a watershed-based Stormwater management
program that goes beyond site-by-site compliance
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Chapter 4: Developing a Stormwater Management Approach and Criteria
watershed projects, and any general conditions for
their application. Technical elements can be in the
stormwater guidance manual.
A local stormwater program can incorporate a regional
or watershed approach through the following means:
• Pro rata share. The stormwater ordinance specifies
that projects within the drainage area (or "service"
area) of a regional or watershed project pay a pro
rata share contribution in lieu of complying with
on-site requirements (at least in part). Generally,
such contributions may be used only to reimburse
construction costs. The mechanics of such a
program (calculation of the "share" based on
discharge, pollutant loads, or impervious cover)
should be included in the guidance manual.
• Fee in lieu. The ordinance may specify that projects
that meet certain criteria may (or must) pay a fee
that contributes to a watershed project in lieu of
some on-site requirements. The fee procedure and
calculations should be included in the guidance
manual, with provision for the fee to reflect realistic
project costs that will probably increase over time.
As opposed to the pro rata share approach, the
fee may be able to be used for a wider range of
project costs, including design, construction, and
maintenance.
Capital improvement program/local
implementation. Even if new development and
redevelopment projects do not contribute funds or
other services to the implementation of watershed
projects, the local program may still wish to adopt
a watershed approach that can be implemented
in parallel with required BMPsat development
sites. In urbanized and urbanizing watersheds,
stormwater retrofitting or stream restoration might
be important strategies to address impacts from
existing development. Individual projects should be
identified in a watershed plan or stormwater master
plan, with implementation strategies tied to the
capital improvement program, grants, cost-share
programs, and other funding sources.
4.7. Detailed Stormwater Management Criteria
Tables
The following tables provide more detailed guidance
on specific language and standards that can be
adapted for stormwater management criteria.
Tables 4.7 through 4.12 address the six criteria
introduced in Section 4.3. Tables 4.13 through 4.17
specify additional criteria for special receiving waters.
The tables provide potential standards; however, it is
important for local stormwater managers to assess and
adapt the most appropriate standards.
The detailed tables address the following criteria:
Basic Criteria
Table 4.7 - Natural Resources Inventory (NRI)
Table 4.8 - Runoff Reduction (RR)
Table 4.9 - Water Quality Volume (WQv)
Table 4.10- Channel Protection (CP)
Table 4.11 - Flood Control (FC)
Table 4.12 - Redevelopment
Special Receiving Waters
Table 4.13 - Lakes and Water Supply Reservoirs
Table 4.14 - Trout and Salmon Streams
Table 4.15 - Groundwater
Table 4.16-Wetlands
Table 4.17 - Impaired (TMDL-Listed) Waters
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.7. Stormwater Criteria for Ordinances and Design Guidance: Natural Resources Inventory
Criterion 1: Natural Resources Inventory (NRI) - Conduct inventory of site natural features.
Explanation
As a first step in site planning, identify natural resources elements that should be protected in order
to reduce Stormwater impacts by design. These elements include natural drainage features, riparian
buffers, wetlands, steep slopes, soils with high infiltration capacity, significant forest, prairie
patches, trees, and natural communities.
A local or state program can provide Stormwater credits for conserving these features and/or using
site design techniques to mitigate impacts on natural resource features. The effect of the credit
is to reduce the required Stormwater volume or treatment requirements for Runoff Reduction,
Water Quality Volume, Channel Protection, and Flood Control (see Criteria 2 through 5, Tables 4.8
through 4.11).
Potential Standards
Identify NRI features on a concept Stormwater plan. Provide credits for designs that protect or
restore NRI features.
Candidate BMPs to
Meet Standards
*• Open space conservation, preservation, reforestation
Conservation of soils with high infiltration capacity
>• Riparian, wetland and waterway buffers
>• Conservation easements
>• Open space or conservation design
Green Infrastructure and Smart Growth planning at community and regional scales
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
Pennsylvania Stormwater Best Management Practices Manual, Ch. 4, Integrating Site Design and
Stormwater Management
http://www.depweb.state.pa.us/watershedmgmt/cwp/view.
asp?a=1437&q=529063&watershedmgmtNav=\
New Jersey Stormwater Best Management Practices Manual,Ch. 2, Low-Impact Development
Techniques
http://www.njstormwater.org/bmp_manual2.htm
Minnesota Stormwater Manual, Ch. 11, Applying Stormwater Credits to Development Sites
http://www.pca.state.mn.us/water/stormwater/stormwater-manual.html
Georgia Green Growth Guidelines, Section I.Site Fingerprinting Utilizing CIS and GPS
http://crd.dnr.state.ga.us/content/displaycontent.asp?txtDocument=969
Urban Watershed Forestry Manual Series, Parts 2 and 3, Center for Watershed Protection and USDA
Forest Service
www.cwp.org > Resources > Special Resource Management > Urban Forestry
Forest Conservation Technical Manual: Guidance for the Conservation of Maryland's Forests During
Land Use Changes Under the 1991 Forest Conservation Act, Metropolitan Washington Council of
Governments (Not available online.)
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.8. Stormwater Criteria for Ordinances and Design Guidance: Runoff Reduction
Criterion 2: Runoff Reduction (RR) - Reduce volume of post-development runoff.
Explanation
Some amount of the post-development runoff should be permanently reduced through
disconnecting impervious areas, maintaining sheetflow to areas of natural vegetation, infiltration
practices, and/or collection and reuse of runoff. More stringent criteria should apply to sensitive
receiving waters.
Groundwater recharge/infiltration requirements should not apply to Stormwater hotspots and
contaminated soils and should be adjusted as appropriate for sites in close proximity to karst,
drinking water supply wells, building foundations, fill slopes, etc.
Areas characterized by high water table, shallow bedrock, clay soils, contaminated soils, and
other constraints should evaluate how much runoff can practically be reduced and modify the
recommended standards accordingly.
Potential Standards
Option 1: Groundwater Recharge/Infiltration
Replicate the pre-development recharge volume, based on regional average recharge rates for
hydrologic soil groups.
>• Residential Sites: Post-development recharge = 90% of pre-development recharge
Nonresidential Sites: Post-development recharge = 60% of pre-development recharge
Option 2: Overall Runoff Reduction
No increase in the overall runoff volume compared to the pre-development condition forall
storms less than or equal to the 2-year, 24-hour storm, OR
Capture and remove from the site hydrograph the volume of water associated with the 80th
percentile storm event (or a locally appropriate and achievable standard—this might be the
90th percentile storm event for areas with good infiltration potential).
Candidate BMPs to
Meet Standards
>• Site design that reduces and disconnects impervious cover
Soil amendments, soil rejuvenation
Rainwater collection and reuse
Pervious parking
>• Bioretention
Rain gardens, on-lot infiltration practices
>• Infiltration swales, trenches, and basins
Enhanced filter strips (with soil amendments and vegetation)
Green roofs
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
Wisconsin Post-Construction Stormwater Management
http://dnr.wi.gov/runoff/stormwater/post-constr
Pennsylvania Stormwater Best Management Practices Manual, Ch. 3, Stormwater Management
Principles and Control Guidelines
http://www.depweb.state.pa.us/watershedmgmt/cwp/view.asp?a=1437&q=529063&watershed
mgmtNav=\
Etowah Habitat Conservation Plan—Stormwater Management Policies
http://www.etowahhcp.org/policies.htm
Best Management Practices for Stormwater Quality, American Public Works Association, Kansas City
Metro Chapter
http://www.kcapwa.net/kcmetro/Specifications.asp
Better Site Design: A Handbook for Changing Development Rules in Your Community, Center for
Watershed Protection, Inc.
www.cwp.org > Online Store > Better Site Design
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.9. Stormwater Criteria for Ordinances and Design Guidance: Water Quality Volume
Criterion 3: Water Quality Volume (WQv) - Capture and treat large percentage of annual pollutant load.
Explanation
Post-development runoff that is not permanently removed through the application of the RR
criterion (Criterion 2, Table 4.8) should be captured and treated in a water quality BMP. This
standard applies to the Water Quality Volume (WQv), or the volume of runoff that contains most of
the annual pollutant load. More stringent criteria should apply to sensitive receiving waters.
States, regions, or localities should evaluate the pollutants of concern that should drive BMP
selection and design. Nationally, the most common pollutants of concern include sediment,
particulate, soluble nutrients (phosphorus and nitrogen), and bacteria. BMPs or combinations of
BMPs thatachieve the highest pollutant load reduction forthe pollutants of concern should be
selected.
Potential Standards
WQv = runoff volume generated by the 90th percentile storm event, based on regional rainfall
frequencies (see Section 4.4).
All runoff removed through the RR criterion (see Criterion #2 in Table 4.8) counts toward treating
the WQv.
The remainder must be treated in an acceptable water quality BMP.
Candidate BMPs to
Meet Standards
Filtering practices—bioretention, sand filters, manufactured filters
Water quality swales, dry swales
>• Linear Stormwater wetlands
>• Stormwater ponds
Vegetated filter strips
Green roof
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
Maryland Stormwater Design Manual
http://www.mde.state.md.us/Programs/WaterPrograms/SedimentandStormwater
Maine Stormwater Best Management Practices Manual, Volume II, Phosphorus Control in Lake
Watersheds: A Technical Guide to Evaluating New Development
http://www.maine.gov/dep/blwq/docstand/stormwater/stormwaterbmps
California Stormwater Best Management Practice Handbooks: New Development and Redevelopment,
California Stormwater Quality Association
http://www.cabmphandbooks.com
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.10. Stormwater Criteria for Ordinances and Design Guidance: Channel Protection
Criterion 4: Channel Protection (CP) - Convey Stormwater to protect downstream channels
Explanation
The Stormwater system should be designed so that increased post-development discharges that are
not mitigated through application of Criteria 1 through Swill not erode natural channels or steep
slopes. This will protect in-stream habitats and reduce in-channel erosion. Conveyance systems
can be designed to reduce Stormwater volume, create non-erosive velocities, incorporate native
vegetation, and, in some cases, restore existing channels that are degraded.
This design process involves careful analysis of the downstream system, beginning with the site's
position within a watershed or drainage area. First, compare the size of the on-site drainage area
at each of the site's discharge points to the total drainage area of the receiving channel or waterway.
Note that the point of analysis might not always be the property boundary of the site, but the point
where the site's discharge joins a natural drainage swale, channel, stream, or waterbody.
The recommended standard below presents a tiered system for CP compliance based on the site/
drainage area analysis discussed above.
Potential Standards
At each discharge point from the site, if the on-site drainage area is less than 10% of the total
contributing drainage area to the receiving channel or waterbody, the following Tier 1 performance
standards must apply:
Tier 1 Performance Standards
>• Wherever practical, maintain sheetflow to riparian buffers or vegetated filter strips. Vegetation
in buffers or filter strips must be preserved or restored where existing conditions do not
include dense vegetation (or adequately sized rock in arid climates).
Energy dissipaters and level spreaders must be used to spread flow at outfalls.
>• On-site conveyances must be designed to reduce velocity through a combination of sizing,
vegetation, check dams, and filtering media (e.g., sand) in the channel bottom and sides.
>• If flows cannot be converted to sheetflow, they must be discharged at an elevation that will not
cause erosion or require discharge across any constructed slope or natural steep slopes.
Outfall velocities must be non-erosive from the point of discharge to the receiving channel or
waterbody where the discharge point is calculated.
At each discharge point from the site, if the on-site drainage area is greater than 10% of the total
contributing drainage area to the receiving channel or waterbody, then the Tier 1 performance
standards must apply plus the following Tier 2 performance standards:
Tier 2 Performance Standards
Sites greater than 10 acres (or a site size deemed appropriate by the local program) must
perform a detailed downstream (hydrologicand hydraulic) analysis based on post-
development discharges. The downstream analysis must extend to the point where post-
development discharges have no significant impact (and do not create erosive conditions) on
receiving channels, waterbodies, or storm sewer systems.
If the downstream analysis confirms that post-development discharges will have an impact on
receiving channels, waterbodies, or storm sewer systems, then the site must incorporate some
orall of the following to mitigate downstream impacts:
(1) Site design techniques that decrease runoff volumes and peakflows.
(2) Downstream stream restoration or channel stabilization techniques, as permitted through
local, state,and federal agencies.
(3) 24-hour detention of the volume from post-development 1-year, 24-hour storm (the volume is
stored and gradually released overa 24-hour period). Runoff volumes controlled through the
application of RR and WQv measures (Criteria 2 and 3, Tables 4.8 and 4.9) maybe given credit
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.10. Stormwater Criteria for Ordinances and Design Guidance: Channel Protection (continued)
Variable Settings
for Stormwater
Management
Possible/Conceptual to Adapt Stormwater Criteria
Potential Standards
(continued)
(toward meeting storage requirements. Discharges to cold water fisheries should be limited to
12-hour detention.
>• Sites less than 10 acres (or a site size deemed appropriate by the local program) must use a
combination of the mitigation techniques listed above and verify that Stormwater measures
provide 12- to 24-hour detention of the volume from post-development 1-year, 24-hour
storm (again, allowing credits through the application of RR and WQv measures). A detailed
downstream analysis is not required unless the local program identifies existing downstream
conditions that warrant such an analysis.
Candidate BMPs to
Meet Standards
Water quality swales
*• Grass swales
>• Level spreaders and energy dissipaters
>• Riparian and floodplain restoration
>• Bioretention with extra volume of soil media and/or underdrain stone
>• Pervious parking with underground storage
Outfall designs that use natural channel and velocity reduction features
>• Ponds and pond/wetland systems that provide peak flow control
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
Stormwater Management Manual for Western Washington, Volumes I and V
http://www.ecy.wa.gov/programs/wq/stormwater/manual.html
Bioretention Design Spreadsheet, North Carolina State University, Stormwater Engineering Group
http://www.bae.ncsu.edu/stormwater/downloads.htm
(system to assign detention credit to bioretention)
Integrated Stormwater Management Design (iSWMD™) for Site Development, Ch. 1, Stormwater
Management System Planning and Design, North Central Texas Council of Governments
http://iswm.nctcog.org
Henrico County, Virginia Environmental Program Manual, Ch. 9, Minimum Design Standards, 9.01,
Energy Dissipater
http://www.co.henrico.va.us/works/eesd
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.11. Stormwater Criteria for Ordinances and Design Guidance: Flood Control
Criterion 5: Flood Control (FC) - Provide peak rate control for larger storms.
Explanation
Peak rates should be controlled in order to reduce downstream flooding. The standard depends
on where a property is situated within a watershed and the design storms that typically cause
flooding in the community. Flood control is customarily a local, regional, or state-driven criterion.
The Flood Control criterion can address one or both of the following, depending on community
priorities:
Overbank Flood Protection: Prevent nuisance flooding that damages downstream property
and infrastructure.
Extreme Flood Control: Maintain boundaries of the pre-development 100-year flood plain,
and reduce risk to life and property from infrequent but extreme storms.
Waivers to the Flood Control criteria should be considered for:
Discharges to large waterbodies
Small sites (< 5 acres in size)
Some redevelopment projects
>• Sites subject to floodplain study that recommends alternative criteria
Sites where on-site detention will cause a downstream peak flow increase compared to
pre-development levels due to coincident peaks from the site and watershed
Communities should evaluate their existing flood control criteria to avoid costly over-control of
peak rates that has marginal downstream benefits.
Potential Standards
Overbank (Minor Storm) Flood Protection:
The post-development peak rate of discharge for the 10-year, 24-hour storm must be reduced to
the pre-development peak rate.
New structures or crossings within the floodplain must have adequate capacity for the ultimate
(build-out) condition.
(NOTE: Minor storm flood control events vary around the country, usually ranging from the 2-year
to the 10-year event.)
Extreme (Major Storm) Flood Control:
The post-development peak rate of discharge for the 100-year, 24-hour storm must be reduced to
the pre-development peak rate.
(NOTE: Major storm flood control events vary around the country, usually ranging from the 25-
year to the 100-year event.)
Candidate BMPs to
Meet Standards
>• Ponds and pond/wetland systems that provide peak flow control
Some underground structures
As applicable, storage under parking lots or within ball fields, open space, etc.
Floodplain and riparian management and restoration, preventing structures within the
100-yearfloodplain
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
Georgia Stormwater Management Manual, Volume 2
http://www.georgiastormwater.com
Floodplain Management Association
http://www.floodplain.org
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.12. Stormwater Criteria for Ordinances and Design Guidance: Redevelopment
Criterion 6: Redevelopment - Provide flexibility to meet criteria for redevelopment conditions.
Explanation
Redevelopment projects can present unique Stormwater challenges due to existing hydrologic
impacts, compacted soils, generally small size and intensive use, and other factors.
Local programs should examine flexible standards for redevelopment, so that Stormwater
requirements do not act as a disincentive for desirable redevelopment projects. This is especially
important within designated redevelopment zones, downtown revitalization zones, enterprise
zones, brownfield sites, and other areas where infill and redevelopment is promoted through local
policies and incentive programs. At the same time, redevelopment offers a unique opportunity to
achieve incremental water quality and/or drainage improvements in previously developed areas
where Stormwater controls might be few or nonexistent. Redevelopment is one of the few chances
to address existing impairments.
Potential Standards
Redevelopment projects must use one or a combination of the following approaches for
Stormwater compliance:
>• Reduce existing impervious cover by at least 20%.
Provide runoff reduction and water quality treatment (Criteria 2 and 3) for at least 30% of the
site's existing impervious cover and any new impervious cover.
>• Use innovative approaches to reduce Stormwater impacts across the site. Examples include
green roofs and pervious parking materials. The local program can exercise flexibility with
regard to sizing and design standards for sites that are attempting to place new practices into a
site with existing drainage infrastructure.
Provide equivalent Stormwater treatment at an off-site facility.
Address downstream channel and flooding issues through channel restoration and/or off-site
remedies.
>• Contribute to a watershed project through a fee-in-lieu payment.
Candidate BMPs to
Meet Standards
See Tables 4.7 through 4.11 for various Stormwater criteria
Off-site mitigation may also include stream or wetland restoration, Stormwater retrofits, and
regional Stormwater solutions
Examples from
Existing Programs -
See Tool 5: Manual
Builder for more
examples and links
City of Philadelphia Stormwater Management Guidance Manual, Cb. 2, Applicability and Approval
http://www.phillyriverinfo.org
Critical Area 10% Rule Guidance Manual, Maryland Critical Area Commission
http://www.dnr.state.md.us/criticalarea/guidancepubs
Developments Protecting Water Quality: A Guidebook of Site Design Examples, Santa Clara Valley Urban
Runoff Pollution Prevention Program
http://scvurppp-w2k.com/Default.htm
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.13. Special Stormwater Criteria for Lakes and Water Supply Reservoirs
Urban watersheds can produce higher unit area nutrient loads
from Stormwater runoff compared toother watersheds (Caraco
and Brown, 2001). Therefore, special Stormwater criteria might
be needed if the receiving waters in urban watersheds are
sensitive to excess nutrients. Nutrient-sensitive waters include
lakes, water supply reservoirs, estuaries, and coastal areas.
Several state, regional, and local Stormwater programs have
developed special Stormwater design criteria for nutrient-
sensitive waters that require development activities to create
no net increase in pollutant loads from the pre-development
condition or to meet site-based load limits (e.g., no more than
0.28 pound/acre/year of total phosphorus). These criteria
focus on achieving this goal using site design techniques and
Stormwater BMPs with a proven rate of pollutant removal
efficiency.
If a designer cannot meet the total removal requirement on-
site, the site owner can be allowed to pay an offset fee for the
difference. This fee is set as the cost of removing an equivalent
amount of pollutants elsewhere in the watershed.
Several states that require Stormwater pollutant load reduction
to protect sensitive waters are listed below.
Maine: To protect sensitive lakes
New York: To protect unfiltered surface water supply
VA/MD: To reduce nutrients delivered to
Chesapeake Bay from shoreline
development
Minnesota: To protect sensitive lakes
For detailed guidance, consult the following resources:
Maine Stormwater Best Management Practices Manual, Volume II, Phosphorus Control in Lake Watersheds: A Technical Guide to
Evaluating New Development
http://www.maine.gov/dep/blwq/docstand/stormwater/stormwaterbmps
Minnesota Stormwater Manual, On. 10, Unified Stormwater Sizing Criteria (Section 9, Lakes)
http://www.pca.state.mn.us/water/stormwater
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Graphic courtesy of Tim McCabe
Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.14. Special Stormwater Criteria for Trout and Salmon Streams
Several state and local Stormwater programs have developed
special Stormwater design criteria to protect trout and salmon
streams. Trout and salmon populations are extremely sensitive
to stream habitat degradation, stream warming, sedimentation,
Stormwater pollution, and other impacts associated with
development. In addition, some poorly designed or located
Stormwater BMPs can induce stream warming that can harm
trout or salmon populations. Without special design criteria,
these sensitive water resources might not be adequately
protected from problems associated with Stormwater runoff.
Some common examples of special design criteria aimed at
protecting trout and salmon streams include:
Requiring the protection and/or restoration of riparian
forest buffers
Requiring groundwater recharge and/or runoff reduction
Requiring downstream channel protection at development
sites (although extended detention times should be limited
to less than 12 hours)
>• Restrictions on the use of Stormwater ponds and wetlands
that can cause stream warming
Preference toward the use of infiltration and bioretention
practices
Requiring that Stormwater BMPs be constructed "off-line" so
they are located away from the stream
*• Requiring that pilot channels, outflow channels, and pools
be shaded with trees and shrubs
Requiring that Stormwater BMPs be planted with trees to
maximize forest canopy cover
>• Requiring that Stormwater BMPs be located away from the
streamside forest buffer to maximize forest canopy cover
and shading in riparian areas
*• Requiring pretreatmentof roadway runoff to reduce
sediment and road salt and sand discharges to receiving
streams
Individual Stormwater BMP design specifications can also be
modified to prevent:
Large, unshaded permanent pools or shallow wetland areas
Extended detention times that are longer than 12 hours
Extensive riprap or concrete channels
Construction of BMPs in on-line or in-stream configurations
For more information, see the North Carolina State University publication Stormwater BMPs for Trout Waters (Jones and Hunt, 2007)
http://www.bae.ncsu.edu/stormwater/pubs.htm
Dane County, Wisconsin, Erosion Control and Stormwater Management Manual, Ch. 3, Stormwater (Section 3.8, Thermal Control) (2007)
http://www.danewaters.com/business/stormwater.aspx
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.15. Special Stormwater Criteria for Groundwater
Groundwater is a critical water resource because many residents
depend on groundwater for their drinking water and the
health of many aquatic systems depends on steady recharge.
For example, during periods of dry weather, groundwater
sustains flows in streams and helps to maintain the hydrology of
wetlands.
Because development creates impervious surfaces that prevent
natural recharge, a net decrease in groundwater recharge rates
can be expected in urban watersheds.
Communities that rely on groundwater as a drinking water
supply have protected groundwater supplies and headwater
streams by developing special criteria to require the infiltration
of a certain volume of Stormwater runoff and require the
use of pretreatment for all Stormwater BMPs. They have also
required the use of low-impact development techniques, such
as impervious disconnection, soil amendments, open space
protection, and/or the maintenance or restoration of a certain
amount of "recharge-friendly" land cover, especially forest.
However, runoff from urban land uses and activities can degrade
groundwater quality if it is directed into the soil without
adequate treatment. Soluble pollutants, such as chloride, nitrate,
copper, dissolved solids,and hydrocarbons can migrate into
groundwater and potentially contaminate groundwater supplies.
Communities should take care to ensure that groundwater
supplies are both maintained with groundwater recharge and
protected from contamination.
The list below contains examples of "Stormwater hotspots."
At these types of sites, infiltration should be discouraged and
source control and pollution prevention measures adopted to
minimize spills, leaks, and illicit discharges.
For examples of Stormwater criteria and standards to protect
groundwater, see Tool 5: Manual Builder.
Potential Stormwater Hotspots (CWP and MDE, 2000)
Vehicle salvage yards and recycling facilities
Outdoor vehicle service and maintenance facilities
Outdoor vehicle and equipment cleaning facilities
Fleet storage areas (bus, truck, etc.)
Industrial sites
Marinas (service and maintenance)
Outdoor liquid container storage
Some outdoor loading/unloading facilities
Public works storage areas
Commercial container nursery
Large chemically managed turf areas
1
Absorption
-•• ^ field
Groundwater***--
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.16. Special Stormwater Criteria for Wetlands
Wetlands are recognized for the many important watershed
functions and services they perform, and their direct
disturbance is closely regulated. However, indirect impacts
associated with Stormwater, such as altered water level
fluctuations and increased nutrient and sediment loads, are
not routinely regulated or even acknowledged. Stormwater
inputs can alter the hydrology, topography, and vegetative
composition of wetlands (Wright etal. 2006). For example,
increased frequency and duration of inundation can degrade
native wetland plant communities or deprive them of their
water supply. The deposition of sediment carried by urban
Stormwater can have the same effect, causing replacement of
diverse species with monotypes of reed canary grass or cattails.
Cappiella etal. (2005) have developed a framework for
protecting sensitive natural wetlands, including special
Stormwater criteria for discharges to wetlands. This information
can be found at the Center for Watershed Protection's
Wetlands Web Site:
www.cwp.org > Resources > Special Resource Management >
Wetlands &Watersheds
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.17. Special Stormwater Criteria for Impaired (TMDL-Listed) Waters
Under the Clean Water Act, water quality standards, which consist of both narrative and numeric criteria, are established
to protect the physical, chemical, and biological integrity of surface waters and maintain designated uses. If water quality
monitoring indicates that these water quality standards are not being met and that designated uses are not being achieved,
surface waters may be added to a list of impaired waters.
When a surface water is listed, a Total Maximum Daily Load (TMDL) study and implementation plan are scheduled for
development. Using water quality sampling and computer modeling, a TMDL study establishes pollutant load reductions from
both point and nonpoint sources needed to meet established water quality standards.
There is increasing emphasis among state and federal permitting agencies to create stronger links between TMDLs and
Stormwater permits, such as MS4 permits (USEPA, 2007; USEPA Region 5, 2007a, 2007b). With successive rounds of MS4
permits, permitted agencies will very likely need to apply more stringent Stormwater criteria in impaired watersheds and/or
provide a better match between particular pollutants of concern and selected BMPs.
Strategies for Local Stormwater Managers to Address TMDLs Through Special Stormwater Criteria
Depending on the nature of the TMDL and the implementation plan, local Stormwater criteria can help address TMDL
requirements. The following three general approaches are discussed in order of decreasing sophistication. There are other
approaches that can applied, and a local program may find that a hybrid approach is most applicable.
Site-Based Load Limits
Surrogate Measures for Sources of Impairment
Presumptive BMP Performance Standards
1. Site-Based Load Limits
Some pollutants that are the basis for TMDLs are understood well enough that site-based load calculations can be done for
each development and redevelopment site. These pollutants generally include sediment, phosphorus, and nitrogen (in some
areas, other pollutants, such as ammonia, fecal coliform bacteria, and other pollutants can be added to the list if adequate local
or regional studies have been conducted) (MSSC, 2005). If site-based load limits are to be used, the TMDL and local Stormwater
program should have the following characteristics:
>• The TMDL allocates a load reduction target to urban/developed land (preferably separating out existing developed land
from estimates of future developed land).
>• The local program uses (or plans to use) a method, such as the Simple Method (CWPand MDE, 2000), that allows for the
calculation of pollutant loads for a particular site development project.
The local, regional, or state manual (or policy document) contains a method to assign pollutant removal performance values
to various structural and nonstructural BMPs. Low-Impact Development (LID) credits are another positive factor so that LID
practices can be incorporated.
The general process for calculating site-based load limits is as follows:
1. Based on the wasteload allocation (WLA) and load allocation (LA) in the TMDL, develop a site-based load limit forthe
pollutant of concern. The local program must allocate the total load reduction goal for urban/developed land to existing
and future urban/developed land within the impaired watershed. The program should consider having a more flexible
standard for redevelopment projects because the standard will usually be more difficult to meet for these projects.
Example: Site-based load limit = 0.28 pounds/acre/year for total phosphorus (Hirschman et al. 2008}
That is, if each newly developed site meets the standard of 0.28 pound/acre/year, the load reduction goal for new urban/developed
land can be met.
In this context, other measures—such as Stormwater retrofits and restoration projects—might have to be applied for existing
urban/developed land (see Step 5 below and Schueler et al. 2007).
2. For each development site, the applicant should calculate the post-development load forthe pollutant of concern using a
recognized model or method. Most use impervious cover as the main basis for calculating loads, although other land covers
(e.g., managed turf) are also important contributing sources.
Example: Post-development total phosphorus load = 0.55 pound/acre/year
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.17. Special Stormwater Criteria for Impaired (TMDL-Listed) Waters (continued)
3. Next, the required load reduction is computed by comparing the post-development load to the site-based load limit, and
an appropriate BMP is selected.
Example: Load reduction = post-development load - site-based load limit
0.55 -0.28 = 0.27pound/acre/year (load that must be removed to meet the load limit standard)
Selected BMPs should be capable of removing the target load reduction. One way to determine this is to calculate the load leaving
the BMP based on the expected effluent concentration and the effluent volume for the design storm (or on an annual basis).
4. Select a combination of structural and nonstructural BMPs that can be documented to meet the required load reduction.
If the local program a nd/orTMDL implementation plan encourages LID, then these practices should be assigned load
reduction credits (see Section 6.10).
5. If the entire load reduction cannot be achieved (or is impractical) on the particular site, the applicant might be eligible
to implement equivalent off-site BMPs within the impaired watershed. These off-site BMP may be implemented by the
applicant on developed land that is currently not served by Stormwater BMPs. Alternatively, the applicant can pay an
appropriate fee (fee in lieu) to the local program to implement Stormwater retrofits within the impaired watershed. In either
case, full on-site compliance is being "traded" to implement other BMPs that can help achieve TMDL goals.
The local program would have to apply this technique to a variety of local plans to gauge achievability and feasibility across a
range of development scenarios.
A good real-world example of this approach (although not specific to impaired watersheds) is Maine's Phosphorus Control in Lake
Watersheds: A Guide to Evaluating New Development (Interim Draft, 12/10/2007).
http://www.maine.gov/dep/blwq/docstand/stormwater/stormwaterbmps
2. Surrogate Measures for Sources of Impairment
If site-based load limits cannot be used because of the type of impairment (e.g..aquatic life) or limited data, surrogates that have
a strong link to the cause of impairment can be used. For instance, various TMDLs have used impervious cover and Stormwater
flow as surrogates for Stormwater impacts on aquatic life, stream channel stability, and habitat (USEPA, 2007). In these cases,
the surrogates are relatively easy to measure and track through time. The TMDL might have a goal to reduce impervious cover
and/or to apply BMP treatment to a certain percentage of impervious cover within the impaired watershed.
A local Stormwater program could apply the surrogate approach through a tiered implementation strategy for new
development and redevelopment (see also Section 4.2):
FIRST, minimize the creation of new impervious cover at the site through site design techniques. Preserve sensitive site
features, such as riparian areas, wetlands, and important forest stands.
SECOND, disconnect impervious cover by using LID and nonstructural BMPs.
THIRD, install structural BMPs to reduce the impact of impervious cover on receiving waters.
3. Presumptive BMP Performance Standards
Perhaps the most widespread and simplest method to NnkTMDL goals with Stormwater criteria is to presume that
implementation of a certain suite of BMPs will lead to load reductions, and that monitoring and adaptive management can help
adjust the appropriate template of BMPs overtime (USEPA, 2007; USEPA Region 5, 2007a). This strategy acknowledges that
data are often too limited to draw a conclusive link between particular pollutant sources and in-stream impairments. However,
as more data become available and TMDL implementation strategies are refined, a more quantitative method, such as the two
noted above, should be pursued.
There are a wide variety of "presumptive" BMPs that can be included in local Stormwater criteria for an impaired watershed, and
these should be adapted based on the pollutant(s) of concern:
Stream/wetland/lake setbacks and buffers
Site reforestation
>• Soil enhancements
>• Incentives for redevelopment
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Table 4.17. Special Stormwater Criteria for Impaired (TMDL-Listed) Waters (continued)
>• Requirements for runoff reduction (see Table 4.8)
Implementation of LID
>• Requirements for BMPs with filter media and/or vegetative cover
Enhanced sizing and/or pre-treatment requirements
Required BMPs at Stormwater hotspots or particular land use categories (e.g., marinas, industrial operations)
>• Contribution to Stormwater retrofit projects within the watershed
The providing channel protection criterion (see Table 4.10) is highly recommended for receiving waters that are impaired by
sediment or sediment-related pollutants. Given the importance of channel erosion in the sediment budget of urban streams, it is
critical to control erosive flows from development projects.
For more information on linking TMDLs to Stormwater permits, see:
Total Maximum Daily Loads with Stormwater Sources: A Summary of 17 TMDLs, EPA 841-R-07-002
http://www.epa.gov/owow/tmdl
Total Maximum Daily Loads and National Pollutant Discharge Elimination System Stormwater Permits for Impaired Waterbodies:
A Summary of State Practices, USEPA Region 5
http://www.epa.gov/R5water/wshednps/topic_tmdls.htm
Linking TMDLs and the Implementation of Low Impact Development/Green Infrastructure Practices, USEPA Region 5
Fora comprehensive primer on Stormwater retrofitting in existing urban/developed land, see:
Urban Stormwater Retrofit Practices, Manual 3, Urban Subwatershed Restoration Manual Series, Center for Watershed Protection,
www.cwp.org> Resources > Controlling Runoff & Discharges > Stormwater Management > National/Regional Guidance.
Managing Stormwater in Your Community
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Chapter 4: Developing a Stormwater Management Approach and Criteria
Managing Stormwater in Your Community
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Chapter
Developing a
Post-Construction
Stormwater Ordinance
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 3
Linking Stormwater to
Land Use
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Post-Construction
Stormwater
Model Ordinance
Companion Tools for Chapter 5
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
Framework for the Stormwater ordinance
Scoping out the right ordinance for the community
• Anatomy of a Stormwater ordinance
Regulatory structure elements
Design elements
Plan review elements
Maintenance elements
> Inspection & enforcement elements
Tips and milestones for building the Stormwater
ordinance
Involving the public in ordinance adoption
Managing Stormwater in Your Community
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
5.1. Framework for the Stormwater Ordinance
General Status and Trends
The Stormwater ordinance is the backbone of a local
program. It provides the legal foundation for all other
program elements, including design standards, devel-
opment review procedures, inspections, maintenance,
and enforcement. Many local programs begin to build
their Stormwater programs by developing and adopt-
ing a local ordinance. While this is often an early step, it
can also be one of the most difficult. As a local regula-
tion, the ordinance must have political support, and
this often involves garnering public support through
education and outreach efforts.
Recent research on NPDES Phase II programs revealed
that about half have adopted some form of storm-
water ordinance. Most of these programs were able
to adopt their local ordinance in 3 years or less (CWP,
2006). Programs that have not yet adopted a storm-
water ordinance note various reasons, including lack of
funding, lack of staff, lack of political support, and lack
of guidance from the state level.
Assess Existing Ordinances
Most communities have existing codes in place that
address Stormwater or drainage in some fashion.
However, existing codes might not support or, in fact,
might be inconsistent with the Stormwater goals that
are expected and required under NPDES MS4 permits.
Chapter 3 outlines some of the most common incon-
sistencies between typical local codes and a "modern"
Stormwater program (e.g., one that promotes good site
design, reduction in impervious cover and disturbed
soils, and innovative BMPs to minimize Stormwater
impacts). Several of these inconsistencies are shown
graphically in Figure 5.1. These inconsistencies can be
particularly acute if the local program wishes to pro-
mote low-impact development (LID) practices.
Tool 4 contains a more thorough "Codes and Ordi-
nance Worksheet" that can be used to systematically
review existing codes and identify inconsistencies with
design approaches that reduce Stormwater impacts. In
many cases, the local program can work to eliminate
these inconsistencies. Some changes to existing codes
will be more difficult than others. For instance, it would
be difficult to change zoning standards that are tied to
statewide uniform building codes, but more straight-
forward to change local standards.
Using Model Ordinances
Many state and regional agencies have model storm-
water ordinances. Many state-level ordinances specify
the technical criteria to be adopted at the local level,
although local adaptation and customization are
expected. Also, many localities begin their ordinance
development process by looking to good examples
from neighboring communities.
Finding and using the most appropriate model is an
important early step in efficiently adopting an ordi-
nance. This step is also an early opportunity to engage
the local legal staff in the development of a Stormwa-
ter ordinance. Tool 3 is a model Stormwater ordinance
that can serve as a good starting point (see Figure 5.2).
Ordinances and Design Standards
The recommended approach for most local programs
is for the ordinance to reference appropriate design
standards (see Chapter 6) but not contain these stan-
dards within the code language itself. The reasons for
this are as follows:
• Design standards should be updated based on
local lessons and improvements in technology. It
can be a burden on the local program to amend
the ordinance each time a design change is sought.
Alternatively, design documents that are amended
through an administrative procedure, with ample
public involvement and input, are more likely to
remain as living documents.
As design standards evolve, they will contain standard
diagrams, computations, and examples. It is quite
burdensome to include these elements within the
confines of a legal document, such as an ordinance.
The ordinance should remain simple and readable
for the widest possible audience. A separate design
standards document can be written for technical
audiences, such as design consultants and plan
reviewers.
Managing Stormwater in Your Community
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
THE LOCAL CODE MAY REQUIRE THIS
BUT NOT ALLOW THIS
Subdivision with no open space
Open-space design
^$j §,
g> 5 p
& S
Curb and gutter on roads
Parking lot islands not used for storm water
Stormwater BMPs address only flood control
Nonstructural BMPs and LID not allowed
Swales and grass channels
Parking lot bioretention areas
Stormwater BMPs address water quality and
resource protection
Nonstructural BMPs and LID given credit
Figure 5.1. Existing codes may conflict wth progressive Stormwater management
Managing Stormwater in Your Community
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
TOOL 3
Post-Construction
Stormwater
Model Ordinance
WATER RESOURCES
PROTECTION ORDINANCE
CITY OF DAR1KR GEORGIA
Adopts .Vjiwfiar.'/. .'«»
ftqwucdOctober IB, JOO>
Other model ordinances to protect local aquatic resources can be found at CWP's Stormwater Managers' Resource
Center (SMRC): http://www.stormwatercenter.net
Information on state-by-state Stormwater regulations can be found at the stormwaterauthority.org Website:
http://www.sfor/T7wciferai/fhorify.org
Figure 5.2. Tool 3: Model Post-Construction Stormwater Ordinance. Other state and regional ordinances are
available around the country
If this approach is taken, the ordinance must be clear
that the relevant design standards are contained in the
latestversion of the design document, or within the
design manual that is updated from time-to-time. This
will ensure that, as the design standards change, the
ordinance requirements will attend to the most up-to-
date version.
Chapter 6 specifically addresses the topic of devel-
oping a Stormwater guidance manual or revising an
existing state or regional manual to meet local needs.
5.2. Getting Started: Scoping Out the Right
Ordinance for the Community
There are many decisions to make when crafting an
ordinance. Many of these will be highlighted and
clarified during program planning and goal setting.
However, it is quite another challenge to translate
general goals and intentions into legal language.
Before mounting the task of drafting the ordinance, it
is important to scope out the unique circumstances in
a given community. These local conditions might be
based on the pace and type of development expected;
natural conditions, such as soils and slopes; or institu-
tional factors, such as the availability of a state model
ordinance and/or design manual. The following scop-
ing questions will help the Stormwater manager frame
the type of ordinance (or ordinance revisions) that is
right for the community.
1. Is there a state or regional model ordinance based
on the state's MS4permit requirements? Is adoption
of this ordinance mandatory or voluntary?
If the Stormwater manager chooses to (or is
required to) use a model ordinance, the drafting
job is simplified. However, the ordinance can still
be tailored to local conditions and needs. For
instance, special Stormwater criteria or additional
maintenance provisions might be appropriate for
the local ordinance.
Managing Stormwater in Your Community
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
2. Do existing local codes pertain to drainage and/or
stormwater?
Existing codes will likely need to be augmented or
overhauled to be consistent with the stormwater
program's current goals and objectives. Refer to
Tools 1 and 4 (Stormwater Program Assessment
and Codes and Ordinance Worksheet) for
guidance on evaluating existing codes.
3. Should the stormwater program be integrated with
erosion and sediment control for construction sites
and/or illicit discharge detection and elimination?
Some level of integration is important. Logical
avenues for integration include a joint ordinance,
a combined development review process, and
an integrated inspection/enforcement program.
Design manuals for erosion and sediment control
and post-construction stormwater might be
separate in some jurisdictions to avoid confusion
and to keep the size of the manuals manageable.
4. What are the permit commitments with regard to
adopting an ordinance?
The Phase II regulations state that stormwater
requirements must be implemented "by ordinance
or other regulatory means." The permit may entail a
specific action and schedule (e.g., adopt stormwater
ordinance by Year 3 of the permit).
5. What are the environmentally significant or
sensitive resources in the community: drinking
water reservoirs, sole source aquifers, areas
subject to flooding, estuaries, wetlands, cold-water
fisheries, recreational lakes and rivers, impaired
waters, pristine streams, or other resources?
Although Phase I and II communities must comply
with regulatory requirements, the best way to
promote a program to the local community is to
base it on local resources. One way to enhance the
ordinance is to include special stormwater criteria
(or watershed-based criteria) for locally important
resources (see Chapter 4 for more detail).
5.3. The Anatomy of a Stormwater Ordinance
Table 5.1 outlines the basic elements of a stormwater
ordinance, arranged into five categories. Subsequent
sections of this chapter describe each element in more
detail. Tool 3: Model Stormwater Ordinance provides
a template for a comprehensive stormwater ordinance.
Table 5.1. Basic Elements of a Stormwater Ordinance
Category 1: Regulatory Structure Elements
The ordinance can be seen as the engine for a stormwater
program. All other program elements must tie back
to adequate or enabling language in the stormwater
ordinance. Basic regulatory elements include:
»• Legal authority and purposes
Definitions
Applicability for stormwater requirements
Exemptions
»• Waivers
Category 2: Design Elements
The ordinance's design elements influence the type, size,
and design of various BMPs that can be used to comply with
the ordinance, including:
»• Stormwater management criteria
»• Regional stormwater and watershed approaches
Category 3: Development Review Elements
The development or plan review process is the chief
compliance tool for a stormwater program. The ordinance
establishes:
Plan submission and review requirements
»• Requirement for a performance bond at plan approval
Category 4: Maintenance Elements
The ordinance must help lay the groundworkfor long-term
maintenance. Important ordinance linkages to maintenance
include:
Easements for stormwater treatment and access to
BMPs
Maintenance agreements to assign long-term
responsibility, as well as operation and maintenance
plans
Maintenance inspection and reporting requirements
Category 5: Inspection and Enforcement Elements
Enforcement tools provided in the ordinance are paramount
fora successful program. Important enforcement
considerations include:
Inspections for permanent BMPs
Penalties and remedies for noncompliance
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Category 1: Regulatory Structure Elements
An effective ordinance must include regulatory ele-
ments to establish basic regulatory parameters as
described below.
Legal Authority and Purposes
This section establishes the legal authority for a local-
ity to manage stormwater, and it is often tied to state
enabling legislation or general police powers of the
jurisdiction. The purposes section establishes the goals
of the ordinance, which should be tied to overall pro-
gram goals. In general, these sections will be specific
to the locality and based on state or federal regula-
tions as well as local goals.
Several examples of items that might be covered in the
purposes section are listed in Table 5.2.
Table 5.2. Purposes Section of a Stormwater
Ordinance
Reduce flooding from land development to protect
stream channels, property, and public safety.
Minimize increases in water pollution caused by
stormwater runoff from land development.
Protect the ecological integrity and quality of stream
networks, surface water, and groundwater.
Ensure that the types, locations, and function of
stormwater management measures are consistent
with the overall growth management goals of the
community.
>• Ensure that all stormwater management measures are
properly maintained.
Definitions
This section provides commonly understood and
legally binding definitions. These terms should be
defined consistently across other related guidance and
regulatory documents.
Applicability for Stormwater Requirements
The applicability provisions dictate how many sites
will be captured in the regulatory process versus those
that are exempt. A local program with existing staff
resources, budget, and community interest will likely
choose a finer mesh size (to catch more sites) than
one without such assets. Applicability is an important
consideration because it determines how many sites
will be subject to plan review and site inspections.
This decision might also dictate how many BMPs will
require ongoing maintenance by a community. Other
considerations are whether criteria will apply to single-
family lots and all redevelopment sites.
EPA's Phase II MS4 stormwater regulations apply to
new development and redevelopment projects that
disturb 1 or more acres, and most state programs
have adopted this same threshold. Local programs
might want or need to adhere to the 1-acre-disturbed
threshold. However, other programs might expand
coverage by using criteria that address other
stormwater concerns, such as:
Impervious cover
Land disturbance smaller than 1 acre
Number of lots in a subdivision
• Watershed characteristics
Table 5.3 lists a range of stormwater applicability crite-
ria in use around the country (CWP, 2006).
The applicability section should state that the thresh-
old applies only to projects that are not part of a larger
common plan of development. A phased project
should consider the entire area being developed under
the various phases.
Exemptions
Exempt projects are categorically excluded from
stormwater requirements (as opposed to variances,
which are evaluated case by case). Some exemptions
are based on state code provisions; for instance, runoff
from agricultural operations is exempt in some states.
Be careful: Exemptions often turn into loopholes. For
example, "logging" and "farm" roads being built under
an exemption have been known to turn into subdivi-
sion streets at a later time. Also, hardship should not
be the basis for exemptions.
Table 5.4 lists the most common exemptions allowed
in stormwater ordinances.
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Table 5.3. Examples of Stormwater Ordinance Applicability Criteria in Use Around the Country
Type of Threshold and Ranges of Values from Surveyed Communities
Impervious Cover
LOW THRESHOLD (more sites covered by ordinance):
100 square feet
HIGH THRESHOLD (fewer sites):
20,000 square feet
Land Disturbance
MOST COMMON:
1 or more acres disturbed (NPDES Phase II MS4 requirement)
LOWER THRESHOLDS (more sites covered):
Any land disturbance
2,500 square feet or more disturbed
20,000 square feet or more disturbed
Number of Lots
LOW THRESHOLD (more sites covered):
1 or more lots
HIGH THRESHOLD (fewer sites):
10 or more lots
Variable
Case-by-case:
All commercial and subdivision plats, plus lot drainage plans
Any new connection to the storm sewer system
>• 2,500 square feet of new impervious or 1,000 square feet of
impervious added to existing development
5,000 square feet disturbed or any new or replacement
impervious cover
Parking lots with 10 or more spaces or 10 or more homes
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Table 5.4. Common Exemptions in Stormwater
Ordinances
>• Projects thatareexc/us/Ve/yforagricultural orforestry
purposes. (Note: The term "exclusively" is necessary to
avoid creating loopholes.)
>• Single-family structures, oradditions or modifications
to single-family structures, that are not part of a larger
project.
Projects that predate the effective date of the ordinance.
Other land uses that might be under the purview of
other agencies or requirements, such as mining, oil and
gas operations, and state/federal agency projects.
>• Temporary projects, such as road and utility
maintenance. However, there is some debate about
whether all temporary projects should be exempt, or
whether these represent opportunities for incremental
improvements in post-construction Stormwater
treatment.
Variances
As described above, variances are considered on a
case-by-case basis. They may be granted for a number
of reasons, including:
• They allow the elected officials to perform
their discretionary duties, such as when overall
public benefit outweighs strict adherence to the
ordinance.
• They allow flexibility in unusual circumstances
where strict compliance isn't practical.
It is important to recognize that granting a variance
does not necessary allow the applicant to avoid any and
all attempts to address Stormwater impacts. The code
must specify the conditions or mitigation measures
that justify granting a variance. Elected bodies should
routinely attach conditions to the granting of a variance.
For instance, the applicant might be required to contrib-
ute land or funds for off-site mitigation or to provide on-
site Stormwater treatment with an innovative practice.
By nature, variances should be limited and applied
very selectively. There are, however, legitimate cases
where the use of variances is warranted, including:
• Variances for water quantity in situations where
Stormwater detention would not be beneficial (e.g.,
along major floodplains) and/or would cause more
environmental damage than benefit (e.g., locating
a detention pond in a natural drainage system). In
cases like these, it is important for the applicant to
demonstrate that there will be no adverse impacts
on downstream channels, structures, or property.
• Variances to allow redevelopment within enterprise
zones, existing town centers, or other areas where
redevelopment is critical to achieve joint economic
development and land use objectives. In some
cases, redevelopment projects will have trouble
meeting all on-site Stormwater requirements, and
these requirements can act as a disincentive for
some redevelopment projects. In these cases, the
program must balance the advantages of having
the redevelopment with the need for full on-site
Stormwater compliance. (See Chapter 3 for more
discussion on Stormwater and land use.)
In all cases, a fee should be associated with applying
for a variance. The fee can cover the staff time needed
to process the waiver and, with more sophisticated
programs, can also be applied to off-site or watershed
projects (conducted by the local program or developer)
in lieu of full on-site compliance. For example, Mary-
land's Critical Area Program specifies an "offset fee"
based on a site's phosphorus loading (CWP, 2003b).
The fee can be applied by the jurisdiction to retrofit or
watershed projects identified in a watershed plan.
Category 2: Design Elements
The ordinance provides the general objectives of
design (criteria), while a separate design guidance
manual can contain the specific design information.
The design portion of the ordinance can also include
the regulatory structure for a regional or watershed-
based Stormwater program.
Design Criteria
Design criteria establish the design objectives for
BMPs, and they will influence directly the types and
sizes of these practices. Programs are expected to
establish criteria that attempt to maintain pre-devel-
opment hydrologic conditions, such as controlling
peak flows and the rate and volume of runoff.
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Traditionally, most programs had criteria for water
quantity (flood) control. More recently, water quality
criteria have become more widespread and are an
important ordinance element for MS4s. Also, some
communities have additional criteria for locally
important resources, such as cold-water fisheries,
groundwater, coastal waters, and drinking water
supplies. These are considered "Special Stormwater
Criteria" and can be adapted for other resources,
including wetlands and impaired waters.
The criteria in the ordinance should remain fairly
simple, with technical detail reserved for the design or
guidance manual. Chapter 4 contains a more detailed
discussion and description of Stormwater manage-
ment criteria that can be included in a Stormwater
ordinance, and Chapter 6 provides information on
developing Stormwater guidance manuals. In addition,
Tool 3: Model Stormwater Ordinance contains model
language for Stormwater management criteria.
Category 3: Plan Review Elements
Chapter 7 provides detailed guidance on the storm-
water plan review process. However, most plan review
functions must tie back to legal authority and require-
ments established in the ordinance. These elements
include both the mechanics of the review process
(e.g., submission requirements and allowable review
periods) and all the documentation that should be tied
to approval of a Stormwater plan (e.g., maintenance
agreements, easements).
Plan Submission and Review
At its basic level, the plan review section outlines the
requirement for plans to be submitted, the sched-
ule for review, and general conditions for approval.
Approving the plan can be a locality's last chance to
influence several important issues, such as ensuring
long-term access to BMPs and assigning maintenance
responsibility. The ordinance should establish the plan
approval process as a mechanism to secure needed
documents for the long-term viability of site BMPs.
A comprehensive plan submission and review section
might include the elements listed in Table 5.5, based
on a program's goals and level of sophistication.
Category 4: Maintenance Elements
The ordinance's role with respect to long-term
maintenance includes the following:
• Ensure that maintenance agreements are recorded
during the development review process. These
agreements (or other ordinance language) should
specify right-of-entry for inspections.
• Ensure that each approved Stormwater BMP has an
adequate operation and maintenance plan, with
practical maintenance checklists and schedules.
These plans can be a component of the recorded
maintenance agreement.
• Ensure that easements for maintenance and access
are platted during the development review process.
Establish maintenance inspection and reporting
requirements.
The other functions of the ordinance in establishing
a maintenance program may include provisions for
compliance, design, and designation of the responsible
party:
• Establish penalties and remedies for noncompliance
with required maintenance tasks (see below under
"Penalties and Remedies").
Establish a general guideline that all Stormwater
BMPs must incorporate design elements to reduce
maintenance and prevent failure (although specific
design guidelines should be in the design manual).
• Establish the responsible party for maintenance. In
many cases, the ordinance will include a definition
for "responsible party" and allow for various
scenarios—private owners, owners' associations,
a government agency or utility, or another private
or public entity specified in the maintenance
agreement.
Establish the requirement for a maintenance
"escrow" account or certificate of financial capability
to be established by the responsible party.
Chapter 9 contains more detailed guidance on
establishing a Stormwater maintenance program.
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Table 5.5. Plan Submission and Review Elements in a Stormwater Ordinance
>• Statement that other permits (building and/or grading permits) may not be issued until a Stormwater plan has been
approved.
>• Requirement for a concept or preliminary plan (this is critically important for plans that have the potential to incorporate
low-impact development).
>• Requirement for a final plan.
Process for accepting plans as complete based on a checklist (which can be contained in the design manual; see Tool 6:
Checklists for specific examples).
Requirement that plans be certified by qualified professionals.
>• Review schedule (e.g., 7 days to determine that a plan is complete and 30 days for review).
Procedure for amending approved plans.
>• Coordination with other federal, state, and local reviews (e.g., erosion and sediment control/construction Stormwater
permits, wetland and stream permits). For instance, include a statement that grading or building permits cannot be issued
until all necessary permits have been obtained.
>• Requirement for necessary drainage and access easements for facilities and conveyances.
Designation of a responsible party for long-term maintenance.
>• Requirement that a maintenance agreement be recorded prior to plan approval. This may also include maintenance plans
for each type of facility (practical maintenance activities and schedules).
>• Requirement for the posting of a performance bond or other surety prior to issuance of building or grading permits. See
Tool 7: Performance Bonds.
Requirement for as-built plans that must be certified by a professional engineer and approved prior to release of
performance bonds.
>• Authority and fee schedule for collecting plan review fees. (The fee schedule may include inspection or other permit fees
as well.)
Category 5: Inspection and Enforcement
Elements
The enforcement elements of the ordinance are
critical to a successful program. The ordinance should
provide various compliance and enforcement tools for
different circumstances. Tool 3: Model Stormwater
Ordinance contains suggested enforcement and
penalty language.
Inspection for Permanent Controls
The inspection section of the ordinance outlines the
requirements for responsible parties to inspect and
report on permanent Stormwater controls. These
inspections should be tied closely with construction-
phase inspections (erosion and sediment control).
Ideally, one inspection section would cover both
functions if the ordinances are combined.
The ordinance should be clear about who is
responsible for conducting inspections—the
responsible party, a local government department,
or a combination—and the type and frequency of
reporting that must be submitted by the applicant.
Inspection language should establish authority for local
program staff to access sites and carry out any enforce-
ment actions (see Penalties and Remedies). Inspection
requirements for permanent controls should include:
Periodic inspections during construction/
installation of permanent controls
As-built inspection to certify that permanent
measures are installed according to approved plans
and stabilized
• Periodic maintenance inspections for the life of the
measure (e.g., at least annually and in response to
complaints)
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
• Minimum reporting requirements (actual inspection
checklists should be in the design manual; see Tool 6:
Checklists)
More sophisticated programs might provide for a sys-
tem of private certified inspectors that receive training
and certification from the stormwater program and
inspect sites on behalf of responsible parties.
Penalties and Remedies
Various options to seek compliance should be estab-
lished in the ordinance to allow flexibility for different
circumstances. Penalties and remedies for stormwater
can be combined with the construction-phase (erosion
and sediment control) and possibly illicit discharge
penalties. However, different enforcement tools will
likely be used during active construction (e.g., stop
work orders) than during the post-construction main-
tenance period (e.g., civil penalties).
Table 5.6 lists and describes the various penalties and
remedies to include in a stormwater ordinance. Often,
a local program will use more informal compliance
methods as a first line of defense. These might include
verbal warnings and warning letters. If these early
attempts do not achieve the desired results, enforce-
ment can escalate to the more formal mechanisms
noted in Table 5.6.
Table 5.6. Types of Penalties and Remedies
Type
Description
Notice of violation (NOV)
Written notice served on the responsible party stating the cause of the violation, remedial steps
to be taken, a schedule for compliance, and consequences for noncompliance (e.g., stop work,
revoking of permits, and pursuit of civil and/or criminal penalties).
Stop work order
Provision for the enforcing agency to stop work on a site if the responsible party fails to comply
with an NOV. A stop work order is more effective for erosion and sediment control (construction-
phase stormwater) than for post-construction stormwater.
Civil penalties or charges
Civil penalties can impose charges for specific violations. The ordinance can include a schedule of
civil penalties (specific charges linked to specific types of violations), and inspectors can use this
schedule in "ticket book" fashion when in the field. Civil penalties provide more flexibility than
criminal penalties.
Criminal penalties
Criminal penalties establish violations as misdemeanors, subject to specific fines and/or
imprisonment. Each day the site is not in compliance is considered a separate violation. Although
criminal penalties represent the biggest "hammer" in the enforcement toolbox, most programs
resort to them rarely and could find it difficult to garner the political support to use such penalties.
Withholding other permits
or approvals
Perhaps the biggest motivator to comply during the construction process is withholding
certificates of occupancy or other approvals until all measures have been properly installed.
This tool would not apply to long-term maintenance, however, and might also present timing
challenges for the applicant and jurisdiction (e.g., site work lags behind building and occupancy).
Revoking or suspending
other permits or approvals
This tool is similar to withholding permits, but it applies to permits or approvals that have already
been granted (e.g., building or grading permits). The appropriate permit or authorization can be
suspended until the required actions are taken, at which point the permit is reinstated. This tool
can be quite effective, but implementing it usually takes political support.
Performance bonds
Performance bonds are not an enforcement tool in the strict legal sense, but many programs use
them to motivate compliance. Bonds can be particularly useful fora stormwater program because
their duration can cover the proper installation of stormwater measures plus a reasonable period
thereafter to ensure that practices function properly. The bond concept can also be expanded to
maintenance in the form of a maintenance bond, escrow, or other financial guarantee that must be
posted by the responsible party. In the ordinance, the performance bond section would likely not
be in the penalties section but rather in the plan submission and review section.
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
5.4. Tips and Milestones for Building the
Stormwater Ordinance
Table 5.7 lists 10 important tips and milestones for
developing and adopting a Stormwater ordinance. The
table lists each milestone, appropriate internal and
external parties that are customarily involved with that
milestone, and an average time frame for the task. Of
course, the actual timeline and parties involved will
vary from community to community.
5.5. Involving the Public in Ordinance
Development and Adoption
The purpose of public participation in the ordinance
development process is to garner public, and ulti-
mately decision-maker, support for (1) the idea that a
Stormwater ordinance is indeed needed (and required)
in the community and (2) the adoption of an ordinance
by the elected officials. The public participation pro-
cess should add value to the final product by incorpo-
rating stakeholder input, ideas, and comments on how
the ordinance can best meet local needs while being
responsive to state and federal requirements.
A short list of public participation methods particu-
larly tailored to the ordinance development process is
provided in Table 5.8. The strengths and weaknesses
of each method are derived, in part, from Randolph
(2004). As noted in the table, there is a trade-off
between the degree of participation and the number
of stakeholders that can be included in the process. For
instance, an advisory committee or ordinance round-
table has a high degree of participation by a limited
number of stakeholders compared to a Web site or
public service announcement. The table lists the meth-
ods based on the degree of participation required,
from high to low.
When developing the public participation strategy,
Stormwater managers should be mindful of the impor-
tant "internal" stakeholders that will help with ordi-
nance development, adoption, and implementation.
These internal stakeholders or agencies can include
(but might not be limited to) the following agencies:
• Planning and community development to
coordinate plan review procedures and design
standards.
Public works department to verify responsibility
for long-term maintenance and the placement of
Stormwater BMPs in relation to public rights-of-way
and easements.
Legal staff to check consistency with federal and
state regulations and permits, check legal language,
and assist with compliance and enforcement tools.
Finance department to assist with fees,
performance bonds, and tracking.
Information/CIS technology to assist with posting
public information materials, maps, and program
tracking.
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Table 5.7. Tips and Milestones for Building the Stormwater Ordinance
Ordinance Milestone
Appropriate Parties
Time Frame
1. Assess existing codes—zoning, subdivision,
drainage, Stormwater.
Stormwater authority
Planning/community development department
>• Stakeholder group
3-6 months
2. Determine permit commitments for Stormwater
ordinance.
Stormwater authority
State MS4 coordinator
1 week
3. Identify relevant state and/or regional model
ordinance or design manual.
Stormwater authority
>• State/regional agencies
State MS4 coordinator
>• Stakeholder group
1 month
4. Make decisions about programmatic
integration with erosion and sediment control,
illicit discharge detection and elimination, and
land use planning.
Stormwater authority
Other local departments involved with aspects
of the Stormwater program
Planning/community development department
>• Stakeholder group
6 months-1 year
5. Devise and execute a public and stakeholder
participation strategy for ordinance
development and adoption.
Stormwater authority
Outreach expert (internal or external)
Legal staff
>• Local leadership (elected and appointed officials)
Other internal and external stakeholders
1-3 years
6. Examine options and make decisions about
applicability threshold, exemptions, waivers,
and design criteria.
Stormwater authority
Stakeholder group
Consultant, if appropriate
3-6 months
7. Determine whether the ordinance should allow
or require low-impact development measures
through variances and/or in design criteria.
Stormwater authority
Stakeholder group
3-6 months
8. Determine whether off-site or watershed
projects are an appropriate site compliance
mechanism in the community.
Stormwater authority
>• Stakeholder group
>• Watershed organizations
Consultant, if appropriate
1-2 years
9. Project annual plan review, inspection, and
maintenance work loads based on applicability
threshold and development rates. Translate to
budget and staffing needs.
Stormwater authority
Public works department
Planning/community development department
Locality's finance/budget office
1-3 months
10. Adopt and implement the ordinance
Stormwater authority
Legal staff
Elected officials
Entire Process:
1-3 years
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Chapter 5: Developing a Post-Construction Stormwater Ordinance
Table 5.8. Public Participation Techniques for Ordinance Development
Technique and Degree
of Participation
Strengths
Weaknesses
High Degree of Participation
Advisory Committee
or Codes Roundtable:
Key stakeholders meet
throughout the process and
might even have a limited
research or writing role.
A full codes roundtable
process involves various
subcommittees.
>• Can build constituency by incorporating an
education process for the committee members.
Provides for continuity throughout the process.
Good tool for soliciting both technical and value-
based input.
>• A successful committee process can be very
influential for decision-makers (especially if they
are involved in the process).
>• Good way to include legal staff, an important
and often overlooked stakeholder, early in the
process.
Difficult to achieve full representation
of all stakeholders.
Requires high degree of commitment
of participants (some stakeholders
cannot attend numerous meetings).
Labor-intensive for staff, unless
outside facilitation and technical
support are provided.
Focus Group(s): One-
time meeting of a diverse
group to gauge reaction to
ordinance approach and
specific actions.
>• Multiple focus groups can reach a variety of
interests.
>• Can focus on specific issues.
>• Can be designed to be interactive.
>• As with committees, can be used to engage legal
staff early in the process.
As with committees, it can be
challenging to fully represent all
interests.
Moderate Degree of Participation
Field Trips, Outreach
Events, Workshops: A
range of events that a re
experiential, visual, and
interactive.
>• Can have a "seeing is believing" impact.
Can be more interactive than formal hearings.
Provides good media opportunities.
>• Adds fun to the process.
Good design is essential to have an
impact—need to involve education
and outreach specialists.
Primarily reaches only those who
want or happen to show up.
Low Degree of Participation
Public Meetings and
Hearings: Usually a more
formal setting to present
ideas or drafts and receive
comments.
Often a necessary step in the latter phases of the
process.
Can be efficient use of staff time.
Difficult to build in meaningful
interaction.
>• Vocal naysayers can dominate and
appear to be the loudest voice.
Can lead to unfounded perceptions
about certain individuals or groups
because there is limited or no
opportunity to interact and share
ideas.
Public Information
Materials: Might include
Web sites, brochures, press
releases, and other media.
Efficient way to reach the greatest number of
people.
Isn't really a form of "participation" and
may have limited impact.
Can be perceived as biased.
A more complete menu of public involvement strategies for MS4s can be found at EPA's Web site:
www.epa.gov/npdes/stormwater/menuofbmps
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Chapfc
Developing Stormwater
Guidance Manuals
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 3
Linking Stormwater to
Land Use
Chapters
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapters
Inspection of
Permanent BMPs
During Construction
Chapters
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Stormwater
Manual Builder
Companion Tools for Chapter 6
Download Post-Construction Tools at:
www.cwp.org/postconstruction
Managing Stormwater in Your Community
Chapter 6
Stormwater Guidance
Manual
What's In This Chapter
Overview of Stormwater guidance manuals
General status and trends in Stormwater guidance
manuals
Scoping out development of a Stormwater guidance
manual
Outlining the policy and procedures manual
Outlining the Stormwater design manual
List of recommended BMPs
3 Stormwater BMP design specifications
Stormwater BMP computations and models
3 Leveling the playing field between LID and
conventional practices: Stormwater credit systems
Building a Stormwater manual: the manual builder tool
Tips for Stormwater guidance manual project
management
Involving the public in developing the Stormwater
guidance manual
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Chapter 6: Developing Stormwater Guidance Manuals
6.1. Introduction
Collectively, all the technical information contained in
the design standards and guidelines will help ensure
that the regulations and requirements that are spelled
out in the ordinance are effectively implemented on
the ground. Ultimately, the information contained
within the stormwater design standards and guide-
lines will influence:
• How well stormwater management will be
integrated with site planning and design
• How both structural and nonstructural stormwater
best management practices (BMPs) will address the
stormwater management criteria established in the
ordinance
The size, appearance, functionality, and safety
of stormwater BMPs, including how they are
landscaped and whether they are designed to
reduce mosquito breeding and other nuisance
conditions
How easily stormwater BMPs can be accessed
for maintenance, and the frequency and type of
maintenance tasks required
Design standards and guidelines need to be spelled
out in detail to ensure that both the designer and plan
reviewer have all the tools and information they need
to properly select, design, review, and approve struc-
tural and nonstructural BMPs. This detailed guidance
is most efficiently and effectively provided within the
context of a stormwater guidance manual.
Fortunately, most states and many regional agencies
have some type of stormwater guidance manual that
can be referenced or adapted by the local program.
This is likely the most cost-effective approach for
providing design information. Many existing manuals,
however, do not have up-to-date guidance and speci-
fications for low-impact development, stormwater
credits, BMP selection and sizing, criteria for sensitive
receiving waters, treatment of stormwater hotspots,
and other features. For this reason, a local stormwater
program may want to, over time, develop a local
addendum or design supplement, or work with rele-
vant state or regional agencies to add this information
to existing manuals. Larger jurisdictions or more
sophisticated programs might find developing their
own design guidance manual desirable.
6.2. Stormwater Guidance Manuals: An
Overview
A stormwater guidance manual is the ideal repository
for all the detailed technical information associated
with stormwater design. Other options are available,
such as providing standards in the ordinance or in a
variety of separate technical and policy documents.
This option might be suitable for small communities
or communities that are in the early stages of building
a stormwater program. However, consolidating the
design standards and guidelines into a well-organized
stormwater guidance manual ultimately leads to a
more efficient and effective stormwater program.
The most effective stormwater guidance manuals
contain two parts:
1. The policy and procedures manual outlines
administrative documents and procedures for
the stormwater plan review, inspection, and
maintenance process.
2. The stormwater design manual contains the
detailed standards and guidance needed by
designers and plan reviewers to select, design,
review, and approve both structural and non-
structural stormwater BMPs at development sites.
In some cases, the two types of manuals are separate
documents. In others, the manuals are combined into
one comprehensive stormwater guidance manual.
Many off-the-shelf resources are available to help
stormwater programs develop both types of manuals.
This chapter provides practical advice on how to
customize these resources to develop effective
stormwater design standards and guidelines.
6.3. General Status and Trends
The following general conditions prevail with regard to
stormwater guidance manuals (CWP, 2006):
• Many communities, and in particular MS4s, provide
some type of guidance in a manual or in the
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Chapter 6: Developing Stormwater Guidance Manuals
stormwater ordinance. Many refer to a state or
regional manual that is already in use.
• Nearly three-quarters of U.S. states have some type
of design manual, but many of the standards and
BMPs have not kept up with recent innovations.
Most manuals do not provide incentives or credits
for the use of low-impact development and/or
nonstructural BMPs.
Most existing manuals address standards for peak
rate (flood) control and water quality treatment.
Fewer manuals also address groundwater recharge,
runoff reduction, downstream channel stability, or
special criteria for sensitive receiving waters (e.g.,
wetlands).
6.4. Getting Started: Scoping Out the
Development of Stormwater Guidance
Manuals
The first step in developing a stormwater guidance
manual is to consider some key decisions about the
manual. Several important scoping questions are pro-
vided below.
1. Is there an existing state or regional stormwater
design manual that can be referenced to serve as the
local manual?
As stated, an existing state or regional stormwater
guidance manual can be incorporated by reference
by a local program. As of fall 2006, approximately
36 states, the District of Columbia, and several
Canadian provinces and U.S. territories had
developed statewide stormwater guidance
manuals. (See Section 6.11 and Tool 5: Manual
Builder for additional information on existing state
and regional stormwater manuals.) In many cases,
a stormwater program may still want to issue a
local design supplement to adequately address
any technical details or local issues that are not
discussed in the state or regional manual.
If a state or regional design manual is not available
as a reference, a local stormwater program can still
make use of the numerous off-the-shelf resources
that are available to develop a stormwater design
manual (see Section 6.11).
2. If there is an existing state or regional stormwater
design manual that can be used as a reference, does
it contain mandatory design standards or voluntary
guidelines or recommendations about the design of
stormwater BMPs?
Many existing state and regional stormwater design
manuals are guidance documents that contain
general recommendations about the design
of stormwater BMPs but no mandatory design
standards that must be used at the local level.
Most state manuals are not "regulations," per se,
but they can be referenced by a local stormwater
ordinance to tie particular design standards to the
ordinance. The bottom line is that, in many cases,
local action is required to "activate" the preferred
design standards. Local program staff should confer
with state agency staff on the regulatory status of
existing manuals and then make strategic decisions
about which material to incorporate by reference
(with or without local adaptations) in local codes
and design guidance documents.
3. If there is an existing state or regional stormwater
design manual that can be used as a reference,
does it include all the technical design guidance
necessary to facilitate the program?
Many state and regional stormwater manuals
developed in the 1980s and 1990s do not contain
guidance on all the elements that should be
included in the local stormwater program. Because
stormwater management is a constantly evolving
field, these older guidance manuals might provide
little or no guidance for items that are now
considered essential parts of a program, such
as the use of low-impact development, source
controls, nonstructural BMPs, and landscaping and
maintenance plans. If the state or regional manual
to be used as a reference does not adequately
address these items, or any other items that might
be outlined in a local ordinance, a local stormwater
design supplement should be developed to
properly address them.
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Chapter 6: Developing Stormwater Guidance Manuals
4. How much educational or background material
should be provided to design consultants and flan
reviewers in the community?
If the information contained in the stormwater
guidance manual will be new to the community,
more educational information may need to be
provided in the manual. Background information on
design equations and illustrative design examples
that guide users through the selection and design
of stormwater BMPs may need to be provided. This
information is extremely valuable to those who
might be seeing the information for the first time,
and it serves as a great reference for local design
consultants.
5. Should information about post-construction
stormwater BMPs and erosion and sediment control
practices be combined into a single manual?
If a community lacks both an erosion and sediment
control (ESC) guidance manual and a stormwater
guidance manual, it can be tempting to combine the
two into a single document. A unified stormwater
manual can lead to greater integration of these two
programs and may provide a platform from which
to launch public education and outreach efforts. If
a unified stormwater manual is created, great care
should be taken to ensure that the manual is kept as
concise and well-organized as possible.
6. What process will be used to update the manual
periodically?
At their best, stormwater manuals are living docu-
ments that can be revised as new technologies
and procedures become available. A premeditated
and scheduled update process will facilitate
maintenance of a modern manual. Updates should
be done as frequently as possible to keep up
with innovations in stormwater technologies and
approaches, regulations, computer software, and
other rapidly changing subjects. At a minimum,
manuals should be updated every 5 years. Also, it
is important that any stormwater ordinances that
refer to the design manual include language to
reference the "most recent version" or "thedesign
manual, as may be updated from time to time."
Standing committees that inform and guide the
update process can also be helpful. Early decisions
about the manual's format will influence the ease
of performing updates. For instance, a manual
in an online or three-ring binder format—where
modifications are fairly simple to incorporate—may
be easier to update than a bound document.
Whatever format is used, care should be taken
to place the date and version number on each
page of the manual so that users know they are
working with the most current version (this applies
especially to online and electronic versions).
6.5. Outlining the Policy and Procedures Manual
After consideration of the key scoping questions
presented above, the next step in developing a storm-
water guidance manual is outlining the technical
content to be included in the manual.
As noted in Section 6.2, this chapter suggests dividing
the manual content into two major sections: (1) policy
and procedures (P&P) and (2) stormwater design. This
section presents information on outlining the P&P
component. Sections 6.6 through 6.11 address the
stormwater design manual components.
A P&P manual should contain the forms, checklists,
and flowcharts that support the implementation of
the local stormwater ordinance. An effective manual
accomplishes the following:
• Clarifies how the local stormwater ordinance applies
to new development and redevelopment projects
and describes which development activities are
exempt from the requirements of the ordinance.
Outlines the local project review process and
highlights the materials and documentation that
must be submitted to facilitate efficient plan review.
Describes the local stormwater BMP construction
and maintenance inspection program and defines
when and how stormwater BMPs will be inspected
during and after construction.
Highlights how stormwater BMPs will be tracked
and monitored by the local stormwater program.
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Chapter 6: Developing Stormwater Guidance Manuals
Includes procedures and forms to be used for the
local program's enforcement program, as outlined
in the ordinance.
A P&P manual should be well organized and relatively
concise. Probably the most intuitive way to organize
the manual is to separate it into sections or chap-
ters that focus on the individual elements of a local
stormwater program. For example, one section can be
dedicated to the plan review process, while another
can be dedicated to the stormwater BMP inspection
program. A typical P&P manual outline is provided in
Table 6.1, and Table 6.2 describes some of this content
in more detail.
6.6. Outlining the Stormwater Design Manual
The design manual contains standards and guidance
on the selection of stormwater BMPs, the sizing and
design of structural and nonstructural BMPs, and the
use of hydrologic, hydraulic, and water quality models
for design.
A well-organized design manual can help ensure that
the requirements of the local stormwater ordinance
are adequately and accurately implemented during
project design. Although the ordinance might define
the general stormwater management criteria fora
development site, the design manual should provide
the detail necessary to select, design, and size a BMP
or series of BMPs that meet the requirements of the
Table 6.1. Typical Policy and Procedures Manual Outline
>• Introduction
- Purpose of Manual
- Relationship of Manual to Local Stormwater Ordinance
>• Ordinance Applicability
- Regulated Development Activities
- Exempted Development Activities
>• Stormwater Plan Review Process
- Application and Submittal Requirements
- Plan Review Flow Chart
- Plan Review Checklists
- Schedule of Other Potentially Required Permits (e.g., state, federal)
- Information about Maintenance Agreements and Plans
- Information about Deeds of Easement
- Performance Bond Program Information
- Project Closeout Information (e.g., As-Built Plans, Certificates of Completion)
- Schedule of Plan Review Fees
- Waiver and Fee-in-Lieu Program Information (e.g.. Alternative Compliance)
Installation of Post-Construction Stormwater BMPs
- Inspection Procedures and Frequencies
- Inspection Checklists
- Enforcement, Violations,and Penalties
Stormwater BMP Maintenance Inspection Program
- Inspection Procedures and Frequencies
- Inspection Checklists
- Tracking and Monitoring Program for Stormwater BMPs
- Enforcement, Violations,and Penalties
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.2. Policy and Procedures Manual Content
Stormwater Plan Review Process
Applications and Documents: An outline of the overall plan review process, a plan review flow chart, application forms and
submittal checklists, submittaI and review timelines, procedures for amending development plans, and an outline of the
decision appeals process (see Chapter 7 for more detail).
Checklists: Checklists for plan review, including checklists for individual Stormwater BMPs that maybe used as part of a
Stormwater plan.
>• Permit Coordination: Information about how local project review will be coordinated with other applicable local, state,
and federal permits programs for activities in wetlands, streams, and floodplains.as well as a schedule of other potentially
applicable local, state, and federal permits.
Maintenance Agreements: Information about maintenance agreement and plan requirements, standard maintenance
agreement forms, and procedures for recording agreements.
>• Operation and Maintenance (O&M) Plan Templates: Templates for O&M plans that are specific to each type of structural
and nonstructural BMP. The templates should include maintenance activities and frequencies for routine and structural
maintenance and should reference any legal agreements in place that guide maintenance. Tool 6: Checklists can help guide
the development of BMP-specific O&M templates.
Easements: Information a bout Stormwater, drainage, and access easements, including a definition of when and where they
must be provided and what their dimensions must be, standard deeds of easement, and procedures for recording easements.
Performance Bonds: Information about local performance bond or"guarantee" programs, including specific program
requirements, standard bond forms, a bond value computation form, and an outline of bond release procedures (see Tool 7).
>• Project Closeout: Information a bout project closeout, including requirements for as-built plan submittal and review, and
procedures for issuing Stormwater certificates of completion.
Fees: A schedule of fees for the plan review process.
Waivers: An outline of the local waiverand fee-in-lieu program, including program requirements, procedures forapproving
waivers and fees-in-lieu, and a schedule of fees.
Chapter 7 of this manual contains additional discussion about the Stormwater plan review program.
Installation of Post-Construction Stormwater BMPs
Inspection Schedule: Procedures for standard construction inspections and times when BMP construction inspections will
occur (e.g., initial site inspection, critical BMP installation stages, final site inspection, as-built confirmation).
>• Checklists: Documentation procedures for inspections, including standard construction inspection checklists.
Enforcement: Requirements for correcting inadequacies found during construction inspections and enforcement tools that
are available for use by the local Stormwater program.
Chapter 8 of this guidance contains additional discussion about the development of a Stormwater BMP construction inspection
program.
Stormwater BMP Maintenance
Inspection Schedule: Procedures for standard maintenance inspections (e.g., either by the Stormwater program or self-
inspections by the owner/operator) and how often the inspections will occur.
>• Checklists: Documentation procedures for inspections, including standard maintenance inspection checklists.
Monitoring: Information about how the results of maintenance inspections will be monitored over the long term.
>• Enforcement: Requirements and timelines for correcting inadequacies found during inspections and enforcement tools that
are available for use by the Stormwater program.
Chapter 9 of this guidance contains additional discussion about the development of a post-construction maintenance program.
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Chapter 6: Developing Stormwater Guidance Manuals
ordinance. In this regard, the design manual serves as
the "users' guide" for program compliance.
Subsequent sections of this chapter provide more
guidance on the recommended elements of a design
manual, including:
List of recommended BMPs (Section 6.7)
• Stormwater BMP design specifications (Section 6.8)
Stormwater BMP computations and models
(Section 6.9)
Stormwater credit systems (incentives for LID)
(Section 6.10)
• The Manual Builder Tool (Section 6.11)
Table 6.3 presents the outline of a typical Stormwater
design manual.
Table 6.3. Typical Design Manual Outline
Introduction
- Purpose of Manual
- Relationship to Local Stormwater Ordinance
General Stormwater Management Information
- Why Stormwater Matters
- General Principles for Stormwater Management
- How Local Conditions Affect Stormwater Management
Stormwater Management Criteria
- Stormwater Management Criteria
- Special Stormwater Design Criteria for Sensitive Receiving Waters
Stormwater BMP Selection
- Approach to Stormwater BMP Design and Selection
- Stormwater BMP Selection Guidance and Selection Matrices
- List of Recommended Stormwater BMPs
- Use of Proprietary Stormwater BMPs
Stormwater BMP Standards and Specifications
- Site Requirements/Feasibility
- Conveyance
- Pretreatment
- Treatment
- Landscaping
- Safety Features
- Maintenance Reduction Features
Stormwater BMP Design Methods and Computations
- Acceptable Hydrologic, Hydraulic, and Water Quality Models
- Required Modeling and Design Assumptions
- Design Examples
Stormwater Credit Program Information
- Available Low-Impact Development (LID) Credits and Applications
- Credit Computation Procedures
- LID Fact Sheets (if not included in Specifications section)
Appendices (e.g.. Design Tools and Resources)
- Approved Plant Lists
- Computer-Aided Design and Drafting (CADD) Details
- Soil and Geotechnical Investigation Guidance
- Other technical support for local program
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Chapter 6: Developing Stormwater Guidance Manuals
6.7. Design Manual: List of Recommended BMPs
In addition to outlining the local approach to BMP
selection, the stormwater design manual should
include a list of structural and nonstructural BMPs that
are recommended for use in the community. A general
approach for the BMP list may be a tiered process, such
as the following:
• Specifically list BMPs that are good matches for
the community in terms of pollutant removal
performance, maintenance burden, aesthetics,
community acceptance, and other factors. The
manual's design specifications will focus on these
BMPs.
• Establish an open-ended process for the acceptance
of other BMPs that developers and design consultants
might ask to use for particular applications. The
process should request consistent information
and be equitable for the various parties seeking
authorization to use various BMPs. (See Tool 8: BMP
Evaluation Tool fora suggested process.)
Provide a more rigorous set of guidelines or
restrictions for BMPs that have proven difficult,
have led to complaints, have an unusually high
maintenance burden, and/or have had performance
problems.
Table 6.4 provides some general guidance on deter-
mining an appropriate set of recommended BMPs.
6.8. Design Manual: Stormwater BMP Design
Specifications
This section of the design manual should contain
stormwater BMP design specifications and typical
details for each of the individual site design, source
control, and structural stormwater BMPs. These specifi-
cations are very important because they influence the
performance, appearance, safety, maintenance burden,
and community benefits provided by the final product.
Stormwater BMP specifications are intended to make
sure the right practice is installed in the right situation.
Nowhere else in the design manual will there be such
a conflict between the need to be prescriptive and the
opportunity to offer designers more flexibility to come
up with creative solutions for a site. This is a situation
where the stormwater manager needs to concentrate
on wordsmithery—particularly with respect to words
like shall and should because these words define which
specifications are mandatory and which are merely
optional or encouraged.
Most stormwater BMP fact sheets address the
following items:
Site Requirements/Feasibility: These specifications
ensure that a stormwater BMP is used only in an appro-
priate setting where it can work effectively. Common
feasibility factors include:
Minimum or maximum contributing drainage area
Slope
Available head
Soil infiltration rate
• Depth to water table
Depth to bedrock
Conveyance: These specifications deal with the
plumbing into and out of the stormwater BMP and its
connection to the storm drain system or discharge to
a stream network. The primary goals are to prevent
erosion at inlets and outlets, provide safe overflow and
adequate conveyance for storms that exceed the water
quality volume, and ensure the right volumes are
diverted for stormwater treatment.
Pretreatment: Pretreatment is absolutely essential
for all types of structural stormwater BMPs to keep
sediment out of the main treatment cell, although
the type, form, and volume of pretreatment practices
often differ between practices. Good stormwater
specifications tend to be numeric and prescriptive with
respect to pretreatment requirements, and they clearly
specify acceptable forms of pretreatment.
Treatment: The performance of most stormwater BMPs
is not governed by only the size of the water quality
volume provided. Other design factors, such as geom-
etry, flow path, media, and residence time, should be
clearly specified to ensure adequate performance.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.4. Developing a Recommended BMP List
The following criteria should be considered when determining a community's recommended BMPs.
Not all BMPs can score high across all of these criteria, but desirable BMPs provide a sufficient level of
performance for most of them.
Provide reliable pollutant removal
performance
Have a sustainable maintenance
burden
Be acceptable to the public
Confer multiple community benefits
Creatively use vegetation
Create habitat but reduce nuisances
Have no unanticipated negative
impacts on the environment
The BMP should employ a sequence of pollutant removal mechanisms that maximize the
removal of key pollutants of concern. BMP performance can be evaluated on the basis of
removal efficiency, effluent concentration, and the documentation of pollutant removal
design features (e.g., pretreatment, filtering, settling,). See Tool 8: BMP Evaluation for more
guidance on BMP performance.
Both routine and nonroutine maintenance tasks should promote longevity, and the life
cycle costs should be manageable so that future owners can maintain the BMP.
The BMP should be viewed by adjacent residents and business owners as an attractive
community amenity and/or landscape feature that adds to rather than detracts from
property values.
The BMP should do more than just treat Stormwater; it should also promote community
greening, recreation, and Stormwater education.
The BMP should use trees and vegetation to promote cooling, shading, screening, and
other landscape functions and should avoid the extensive use of irrigated turf.
The BMP should create both aquatic and terrestrial habitat and should be designed to
avoid nuisance problems such as resident geese and mosquito breeding.
The BMP should not create any negative environmental impacts, such as stream warming
or groundwater contamination.
Landscaping: Enhancing the appearance and com-
munity benefits of a Stormwater design is frequently
overlooked in BMP specifications. The trend in recent
years is to require landscaping plans for every practice
and to provide detailed landscaping guidance in a
manual appendix.
Safety: Stormwater specifications should be clear on
how safety hazards, such as deep pools, sharp drop-
offs, riser access, and other safety problems will be
minimized in both design and construction. The trend
in recent years has been to manage risk by preventing
unsafe contours and using dense vegetation to control
access to certain areas (rather than excluding people
through unsightly fences). Given potential liability con-
cerns, communities should be very clear and specific
about what is required to protect public safety.
Maintenance: Good Stormwater specifications focus
on criteria to reduce the maintenance burden for the
Stormwater BMP and make maintenance tasks easier
to perform. Including good maintenance-reduction
criteria in Stormwater specifications reduces the long-
term maintenance burden and life-cycle cost of BMPs.
Specifications should always make sure that future
owners have easy access to the parts of the practice
that need to be inspected and maintained. Table 6.5
lists several examples of maintenance-reduction design
specifications. Chapter 9 provides additional informa-
tion on maintenance design recommendations, as well
as various approaches for maintenance responsibility.
Tool 5: Manual Builder can be used to find good
examples from around the country for BMP design
specifications.
6.9. Design Manual: Stormwater BMP
Computations and Models
This section of the manual provides detailed guidance
on the actual design of Stormwater BMPs by outlining
required design assumptions; providing an overview of
the acceptable hydrologic, hydraulic, and water quality
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.5. Examples of Maintenance Reduction Criteria (CWP and WIDE, 2000; CWP, 2004)
Access paths within easements, with load-bearing capacity suitable for maintenance equipment, should extend to all major
stormwater BMP features, including the pretreatment facility, inflow points, outfall, filter beds, embankment, and riser area.
Maintenance access paths should be at least 12 feet wide, have a maximum slope of 15%, and be appropriately stabilized (e.g.,
reinforced turf) to withstand maintenance equipment and vehicles.
Pretreatment facilities should be designed to allow for sediment removal and regular maintenance. For example, use a hard
surface such as concrete pavers for the bottom of a sediment forebay. For underground practices, locate a large manhole
opening directly over the sedimentation chamber and ensure that a vactor truck can access the manhole. Maintenance clean-
out elevations should be physically marked on pretreatment structures.
Stormwater ponds and wetlands should be designed to allow for sediment removal and provided with a designated on-site
disposal area or, at minimum, an on-site dewatering area.
Filtration and infiltration practices should be designed to allow for filter bed removal and replacement.
>• Outlet structures must be located within embankments for maintenance or emergency access and should be accessible
during storm events.
>• Access to outlet structures must be provided by lockable manhole covers and, if necessary, manhole steps within easy reach of
valves and other controls.
Principal spillways must be equipped with a trash rack that provides access for maintenance.
>• Stormwater ponds, wetlands, and infiltration practices must be equipped with an underdrain system that can completely
drain the treatment cell within 24 hours. The underdrain must be equipped with an adjustable valve and should be over-
designed (one pipe size greater than the required design diameter). Underdrain valve controls must be located inside the
outlet structure at a location where they will not normally be inundated.
>• Low-flow orifices must have a minimum diameter of 3 inches and must be adequately protected from clogging by an
acceptable external trash rack. Use of non-clogging low-flow orifice designs, such as the reverse-slope pipe in a permanent
pool or the perforated half-round corrugated metal pipe (CMP), is recommended. Perforated pipe covered with filter cloth is
not recommended because of the potential for clogging.
Infiltration practices must have an observation well consisting of an anchored, 6-inch-diameter perforated PVC pipe with a
lockable cap.
>• Stormwater ponds and wetlands must have a staff gauge (graded measuring stick) to consistently measure the depth of
sediment and the permanent pool elevation.
A warranty must be provided with all landscaping installations.
>• Proprietary BMPs should be covered by a maintenance contract with a qualified maintenance firm before a certificate of
occupancy is issued.
>• See Chapter 7 for additional information on stormwater maintenance programs.
models that can be used for design; and providing a
number of design examples to illustrate the required
local approach.
The foundation of stormwater design is understanding
the relationship between the characteristics of a
particular drainage area and the stormwater runoff
that passes over it. In particular, the relationship
between land cover and stormwater quality and
quantity must be analyzed. A hydrologic, hydraulic, or
water quality model is needed whenever an estimate
of these stormwater characteristics is needed for
stormwater BMP design.
The design manual should provide guidance on
acceptable hydrologic, hydraulic, and water quality
models. The design manual should also identify the
assumptions that must be made during modeling and
BMP design. This last item is particularly important—
modeling assumptions play a significant role in
stormwater BMP design. Some examples of typical
modeling assumptions are presented in Table 6.6.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.6. Examples of Typical Modeling and Design Assumptions
>• The Rational Method (Q=CiA) will be acceptable for drainage areas less than 20 acres.
For drainage areas greater than or equal to 20 acres, the most recent update ofTR-55, TR-20, and/or HEC-HMC will be used as
basis of design.
Predevelopment land use will be considered to be forest or meadow in good condition, regardless of the actual condition at
the time of application.
>• Hydrologic parameters will reflect the ultimate build-out of the land development project, and the land development project
as a whole; individual lots will not be considered separate land development projects.
>• Runoff calculations for all off-site areas will be based on existing land use conditions or anticipated future land use conditions.
Site impervious cover will be directly measured from the site plan.
>• For determination of soil runoff characteristics, areas that are hydrologically disturbed and compacted will be changed to the
next hydrologic soil group (one that has higher runoff potential; for instance, change a "B" soil to a "C" soil).
>• The length of overland flow used in time of concentration calculations will be no greater than 150 feet (pervious cover) or
75 feet (impervious cover).
Rainfall data, as approved by the local Stormwater program, will be used for rainfall volume, storm distribution, return
frequency, and event duration.
Some interaction between Stormwater designers and
Stormwater program staff is needed to gain consensus
on acceptable models and modeling assumptions.
Modeling Overview
A wide variety of models are available for performing
hydrologic and hydraulic calculations, and these
models are used for many purposes. The most
common uses include:
Characterize Stormwater runoff in terms of peaks
and volumes
• Predict the impacts of watershed changes
• Determine the effects of Stormwater management
practices
• Perform hydraulic design
• Provide input to other models
The decision to use a model, and which model to use, is
an important part of Stormwater management planning.
Even though there are no clear rules on how to select
the right model, a few simple guidelines can be stated:
1. Define the problem and determine what
information is needed and what questions need to
be answered.
2. Use the simplest method that can answer the
questions and that has an acceptable level of
accuracy.
3. Do not try to fit the problem to a model, but try to
select a model that fits the problem.
4. Question whether increased accuracy is worth the
increased effort. (With the advances in computer
technology, computational cost is hardly an issue
anymore.)
5. Do not forget the assumptions underlying the
model used, and do not read more significance into
the simulation results than is actually there.
Hydrologic models are used to estimate runoff
volumes, peak flows, and the temporal distribution of
runoff at a particular location resulting from a given
precipitation record or event. Essentially, hydrologic
models are used to predict how the site topography,
soil characteristics, and land cover will cause runoff
either to flow relatively unhindered through the
system to a point of interest or to be delayed or
retained somewhere upstream. Many hydrologic
models also include relatively simple procedures to
route runoff hydrographs through storage areas or
channels, and to combine hydrographs from multiple
watersheds.
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Chapter 6: Developing Stormwater Guidance Manuals
Hydraulic models are used to predict the water
surface elevations, energy grade lines, flow rates,
velocities, and other flow characteristics throughout
a drainage network that result from a given runoff
hydrograph or steady flow input. Generally, the output
(runoff) from a hydrologic model is used as the input
to a hydraulic model. The hydraulic model then uses
various computational routines to route the runoff
through the drainage network, which might include
channels, pipes, control structures, and storage areas.
Combined hydraulic and hydrologic models
provide the functions of both hydraulic models and
hydrologic models in one framework. A combined
model takes the results from the hydrologic portion of
the model and routes them through the hydraulic por-
tion of the model to provide the desired estimates.
A variety of common hydrologic and hydraulic models
are summarized in Table 6.7. Table 6.8 provides more
detail about these models and their applications (Akan
and Houghtalen, 2003; Huber et al. 2006).
Table 6.7. Summary of Hydrologic and Hydraulic Models
Model or Tool
Input Complexity
Continuous Modeling
Public Domain
Rainfall-Runoff Calculation Tools:
peak flow, runoff volume, and/or event hydrograph calculations only
Rational Method (equation)
Low
No
Yes
Hydrologic Models:
rainfall-runoff simulation, reservoir and channel routing
TR-55
HEC-HMS
WinTR-20(orTR-20)
Low
Medium
Medium
No
Yes
No
Yes
Yes
Yes
Hydraulic Models:
water surface profile determination along waterways and through structures
CulvertMaster
Flow/Master
HEC-RAS
WSPRO
Low
Low
Medium
Medium
No
No
Yes
No
No
No
Yes
Yes
Combined Hydraulic and Hydrologic Models:
rainfall-runoff results automatically input into hydraulic calculation module
HydroCAD
PondPack
EPA-SWMM
XP-, PC-, MIKE- SWMM
Medium
Medium
Medium/High
Medium/High
No
No
Yes
Yes
No
No
Yes
No
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.8. Description and Applications for Various Models
Rational Method
The rational method is a simple calculation of peak flow based on drainage area, rainfall intensity, and a non-dimensional runoff
coefficient. The peak flow is calculated as the rainfall intensity in inches per hour multiplied by the runoff coefficient and the
drainage area in acres. The peak flow, Q, is calculated in cubic feet per second as Q = CM, where C is the runoff coefficient,/is the
rainfall intensity, and A is the drainage area. This method is best used only for simple approximations of peak flow from small
watersheds.
TR-55, Urban Hydrology for Small Watersheds
Win TR-55
Technical Release 55 (TR-55): Urban Hydrology for Small Watersheds was developed by the U.S. Department of Agriculture (USDA)
Soil Conservation Service (SCS), now the Natural Resources Conservation Service (NRCS), in 1975 as a simplified procedure to
calculate storm runoff volume, peak rate of discharge, hydrographs, and storage volumes. In 1998 Technical Release 55 and the
computer software were revised to what is now called WinTR-55. WinTR-55 is a single-event, rainfall-runoff small watershed
hydrologic model. The WinTR-55 generates hydrographs from both urban and agricultural areas at selected points along the
stream system.
WinTR-55 is available on the NRCS Web site. The model and support documentation can be downloaded for free at:
http://www.wsi.nrcs.usda.gov/products/W2Q/H&H/Tools_Models/WinTR55.html
HEC-HMS
HEC-HMS is a rainfall-runoff model developed by the U.S. Army Corps of Engineers to compute runoff hydrographs for a network
of watersheds. The model evaluates infiltration losses, transforms precipitation into runoff hydrographs, and routes hydrographs
through open channel routing.
The HEC-HMS program is available to the public and can be downloaded from the U.S. Army Corps of Engineers Web site:
http://www.hec.usace.army.mil/software/hec-hms
TR-20
Technical Release No. 20 (TR-20): Computer Program for Project Formulation Hydrology was developed by the hydrology branch
of the USDA Soil Conservation Service in 1964. TR-20 is a single-event rainfall-runoff model that is typically used with a design
storm for rainfall input. The program computes runoff hydrographs, routes flows through channel reaches and reservoirs, and
combines hydrographs at confluences of the watershed stream system.
The TR-20 program is available to the public and can be downloaded from the NRCS Web site:
http://www.wsi.nrcs.usda.gov/products/W2Q/H&H/Tools_Models/WinTR20.html
HEC-RAS
HEC-RASisa river hydraulics model developed by the U.S. Army Corps of Engineers to compute one-dimensional water surface
profiles for steady or unsteady flow. Computation of steady-flow water surface profiles is intended for floodplain studies and
floodway encroachment evaluations. Unsteady flow simulation can evaluate subcritical flow regimes, as well as mixed flow
regimes including supercritical, hydraulic jumps, and drawdowns. Sediment transport calculation capability will be added in
future versions of the model.
The HEC-RAS program is available to the public and can be downloaded from the U.S. Army Corps of Engineers Web site:
http://www.hec.usace.army.mil/software/hec-ras
WSPRO
WSPRO is a model for water surface profile computations developed by the U.S. Geological Survey. The model evaluates one-
dimensional water surface profiles for systems with gradually varied, steady flow.
The WSPRO program is available to the public and can be downloaded from the U.S. Geological Survey Web site:
http://water.usgs.gov/software/wspro.html
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.8. Description and Applications for Various Models (continued)
CulvertMaster
CulvertMasterisa hydraulic analysis program for culvert design. The model uses the Federal Highway Administration's Hydraulic
Design of Highway Culverts methodology to provide estimates for headwater elevation, hydraulic grade lines, discharge, and
culvert sizing.
CulvertMaster is a proprietary model that can be obtained from Bentley Systems, Inc.:
http://www.bentley.com/en-US/Products/CulvertMaster
Flow/Master
FlowMaster is a hydraulic analysis program used for the design and analysis of open channels, pressure pipes, inlets, gutters, weirs,
and orifices.
FlowMaster is a proprietary model that can be obtained from Bentley Systems, Inc.:
http://www.bentley.com/en-US/Products/FlowMaster
HydroCAD
HydroCAD is a computer-aided design program for modeling the hydrology and hydraulics of Stormwater runoff. Runoff
hydrographsare computed using theSCS runoff equation and the SCSdimensionless unit hydrograph. HydroCAD has the ability
to simulate backwater conditions by allowing the user to define the backwater elevation before simulating a rainfall event.
HydroCAD is a proprietary model that can be obtained from HydroCAD Software Solutions, LLC: http://www.hydrocad.net
PondPack
PondPackis a program for modeling and design of the hydrology and hydraulics of Stormwater runoff and pond networks.
Rainfall analyses can be conducted using a number of synthetic or historical storm events, using methods such as SCS rainfall
distributions, intensity-duration-frequency curves, or recorded rainfall data. Outlet calculations can be performed for outlets like
weirs, culverts, orifices, and risers. The program can assist in determining pond sizes.
PondPack is a proprietary model that can be obtained from Bentley Systems, Inc.:
http://www.bentley.com/en-US/Products/PondPack
SWMM-Based Programs
The Storm Water Management Model (SWMM) was originally developed for the U.S. Environmental Protection Agency (EPA) in
1971 by Metcalf and Eddy, Inc., Water Resources Engineers, Inc., and the University of Florida. SWMM is a dynamic rainfall-runoff
and water quality simulation model, primarily but not exclusively for urban areas, for single-event or long-term (continuous)
simulation.
SWMM is a comprehensive computer model for analysis of quantity and quality problems associated with urban runoff. It can
be used for planning and design. The planning models used for an overall assessment of urban runoff problem or proposed
abatement options.
The SWMM program is available to the public and can be downloaded from the U.S. Environmental Protection Agency's Web site:
http://www.epa.gov/ednnrmrl/models/swmm
The proprietary shells, XP-SWMM and PC-SWMM, provide the basic computations of EPA-SWMM with a graphic user interface,
additional tools, and some additional computational capabilities. XP-SWMM is available on theXP Software company Website:
http://www.xpsoftware.com
PC-SWMM is available on the Computational Hydraulics International Web site:
http://www.computationalhydraulics.com
References: Akan and Houghtalen, 2003; ARC, 2001; Hydrocomp Inc., 2008; MSSC, 2005; PA DEP, 2006; Huber et al. 2006.
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Chapter 6: Developing Stormwater Guidance Manuals
6.10. Design Manual: Leveling the Playing Field
between Low-Impact Development (LID)
and Conventional Practices—Stormwater
Credit Systems
Oftentimes, low-impact development practices (LID)
are not used because there is no local system to get
them approved on development plans. Even if all par-
ties involved (plan reviewers, developers, design con-
sultants) are interested in LID practices, they cannot be
fully incorporated unless they are considered coequal
to more conventional practices, and their benefits for
water quality and runoff reduction are counted in the
local compliance process.
Most conventional BMPs have well-defined sizing and
water quality computation procedures by which the
local reviewer can establish compliance. However,
computational methods for LID are more uncertain
and less widely known and accepted.
Even with these difficulties, there are benefits to
be derived from incorporating LID into site design,
including:
• In some cases, LID can be more economical for the
developer while still providing effective Stormwater
treatment (if properly designed, implemented, and
maintained).
• These measures can also reduce the size and/or
footprint of conventional, structural Stormwater
conveyance and treatment systems needed at a site.
Most LID techniques have aesthetic benefits and
can enjoy wider homeowner acceptance compared
to certain conventional practices. For instance,
a restored riparian buffer and grass channels
are usually more acceptable to the public than a
conventional "backyard" basin.
• Use of LID allows the site designer to tailor
Stormwater solutions to the particular conditions
and opportunities at the site. For example, if a
site has many unbuffered streams or open spaces
previously used for agriculture, restoration plans
can become part of the Stormwater mix.
Certain LID techniques can be coordinated with
land use strategies to protect water resources.
An example is encouraging shared parking, and
thus a reduced parking lot footprint, in areas
where the locality wishes to encourage infill and
redevelopment.
An emerging way to incorporate LID into Stormwater
compliance systems is to consider the ability of various
practices to reduce the overall volume of runoff. "Run-
off reduction" tends to level the playing field between
LID and conventional practices because it provides a
common denominator that can be ascertained for a
fuller range of practices than are typically allowed in
local and state Stormwater manuals.
Runoff reduction can be defined as the total annual
runoff volume reduced through canopy interception,
soil infiltration, evaporation, transpiration, rainfall
harvesting, engineered infiltration, or extended
filtration. By nature, BMPs that reduce the overall
volume of runoff also reduce pollutant loads, and they
can also help mitigate other Stormwater concerns,
such as downstream channel erosion and reduced
groundwater recharge.
Chapter 4 (Table 4.8) provides more detail on runoff
reduction as a Stormwater management criterion.
Table 6.9 lists the runoff reduction capabilities of vari-
ous conventional and LID practices based on an exten-
sive literature search (Hirschman et al. 2008). The
values in the table are generally average annual runoff
reduction rates from research studies, and they pertain
chiefly to smaller storm events (e.g., 90th percentile
rainfall event or less—equivalent to the "water quality
volume"; see Table 4.9).
Various state programs are updating their Stormwater
regulations and handbooks to incorporate the prin-
ciples of runoff reduction. Hirschman et al. (2008)
provides a comprehensive compliance system, includ-
ing a spreadsheet tool, that can be used or adapted
to provide credit for runoff reduction practices. This
system is based specifically on reduction in nutrient
loads, but it could be adapted to other pollutants of
concern (see wwiv.civp.org > Resources > Controlling
Runoff & Discharges > Stormwater Management >
National/Regional Guidance).
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.9. Runoff Reduction for Various BMPs
Stormwater Practice
Green Roof
Rooftop Disconnection
Raintanks and Cisterns
Pervious Parking
Grass Channel
Bioretention
Dry Swale
Wet Swale
Infiltration
Extended Detention Pond
Soil Amendments
Filter Strip; Sheetflow to
Open Space
Filtering Practice
Constructed Wetland
Wet Pond
Runoff Reduction Rates
from Literature (%)a
45-60
25-50
Amount captured and reused
45-75
10-20
40-80
40-60
Less than 10%
50-90
0-15
50-75
50-75
Less than 10%
Less than 10%
Less than 10%
a Ranges of values are for different design components that vary in
their ability to promote runoff reduction. For instance, bioreten-
tion that is designed for infiltration into the subsoil has a higher
runoff reduction rate than bioretention with an underdrain,
where infiltration rates are less.
Also, values represent average annual reductions based on
research studies. The values are relevant chiefly for smaller
storm events — approximately the 90th percentile rainfall event
or less. Some runoff reduction can also be achieved for larger
events (channel protection and/or flood control runoff events),
but the values would likely be adjusted depending on site runoff
characteristics.
Source: Hirschman et al. 2008.
A number of other state and local Stormwater pro-
grams have crediting procedures for LID that a storm-
water program can tailor to its own needs. References
and web links to several of these programs are pro-
vided in Tool 5: Manual Builder. See also the resources
listed in Tables 4.7 and 4.8 concerning site natural
resource inventories and runoff reduction criteria.
The design manual plays a critical role in establishing a
Stormwater credit system. The manual should describe
each credit, indicate how it is computed, outline
required site conditions, highlight restrictions to where
it can be applied, and conclude with a numerical
design example.
Not all credits are available for each development site,
and certain site-specific conditions must be met to
receive each credit. These minimum conditions include
site factors like maximum flow length or contributing
area. These "eligibility criteria" help to avoid situations
that lead to runoff concentration, erosion, and possible
drainage complaints. An example of eligibility criteria
needed to receive a Stormwater credit for grass chan-
nels is provided in Table 6.10.
As an additional resource, Tool 6: Checklists provides
plan review, construction, and maintenance inspection
checklists for various nonstructural practices that can
be considered for Stormwater credits.
Experience in other states has shown that it can take a
while for both local plan reviewers and engineering con-
sultants to understand and effectively use Stormwater
credits during site design and plan review. Adoption
of credits is particularly difficult in communities where
Stormwater design occurs long after site layout, giving
designers and plan reviewers little chance to apply LID
techniques and the corresponding credit system.
Four ingredients appear to be important in
establishing an effective local credit system:
Strong interest and some experience in the use of
LID techniques.
A development review process that emphasizes
early Stormwater design consultations during and
prior to initial site layout. Such procedures as pre-
submittal meetings and concept plans are strongly
encouraged.
Effective working relationships between plan
reviewers and design consultants.
A commitment by both parties to field verification
to ensure that credits are not a paper exercise.
If a community feels that it has many of these
ingredients in place, the local program should start to
develop a Stormwater credit system.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.10. Eligibility Criteria for Grass Channel Credit
Eligibility: A qualifying grass channel meets the following criteria:
>• Primarily serves low to moderate residential development, with a maximum density of 4 dwelling units per acre
The bottom width of the channel should be between 4 and 8 feet wide.
>• If suitable soil amendments are provided for channels in C/D soils, the 20% runoff reduction rate maybe used. For channels in
A/B soils, soil amendments are not needed so long as soils are protected during site construction.
>• Channel side-slopes should be no steeperthan 3H:1V
The longitudinal slope of the channel should be no greater than 2%. (Checkdamsora terraced swale design may be used to
break up slopes on steeper grades.)
The maximum contributing drainage area to any individual grass channel should be 5 acres.
>• The dimensions of the channel should ensure that runoff velocity is non-erosive during the 2-year design storm event and
safely convey the local design storm (e.g., 10-year design event).
>• Designers should demonstrate that the channel will have a maximum flow velocity of 1 foot per second during a 1-inch storm
event.
See Tool 5: Manual Builder for additional Stormwater credit design references.
For a fuller overview of the topic of Stormwater BMP
performance for both conventional and innovative
practices, see EPA's online Urban BMP Performance
Tool: www.epa.gov/npdes/urbanbmp
6.11. Building a Stormwater Manual: The Manual
Builder Tool
Once the scope of the local Stormwater guidance
manual has been determined and a manual outline
developed, the next step is to actually build the
manual. This section provides information about the
development of a Stormwater guidance manual and
information on how to use existing state and regional
Stormwater manuals and existing off-the-shelf storm-
water resources.
At the outset, the Stormwater manager should keep
in mind several do's and don'ts of manual writing that
have been acquired through hard-won experience
across the country. These tips are profiled in Table 6.11.
There are a significant number of existing state,
regional, and local Stormwater management guidance
manuals that can be used to develop a local manual.
Tool 5: Manual Builder was created to help storm-
water managers sort through these existing manuals
to find the information they need to most efficiently
develop a local manual.
A total of 51 state, regional, and local Stormwater
management guidance manuals were reviewed to
develop the Manual Builder tool. These manuals are
listed in Table 6.12. If the manuals were stacked on
top of each other, the pile would be more than 10 feet
high (see Tool 5 for links to these documents on the
Internet). The stack would contain tens of thousands
of pages of material, much of which is redundant or
recycled from other manuals.
To help Stormwater managers most efficiently find the
information they need to build a Stormwater guid-
ance manual, the Manual Builder tool indexes exist-
ing design and policy and procedures manuals by the
best examples in a variety of topic areas, as listed in
Table 6.13.
Stormwater managers can use the tool to quickly
find good information on the topics they are most
interested in. Once the most appropriate material is
identified, it can be customized to fit local conditions.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.11. Manual Writing Do's and Don'ts
Do:
Clearly indicate what is required, recommended, or merely encouraged.
>• Keep the manual as concise as possible.
Describe why the management of post-construction Stormwater is important.
Organize the manual in such a way that users can quickly find the information they need.
Provide documentation to support the local Stormwater management criteria and design requirements.
>• Check every equation three times.
>• Allow the manuals to be revised administratively.
Place the date and version number on each page of the manual so users know they a re working with the most current
version.
Consider making the manual available on a CD or as a Web-based document to better facilitate distribution.
Place design tools and resources in appendices, where they can be added or removed as necessary.
>• Solicit input from the design and development community. Consider forming a technical review committee composed of
municipal staff and outside stakeholders.
Don't:
>• Include a lot of unnecessary background information.
Expect folks to read the manual from cover to cover.
>• Randomly cut and paste from another manual without careful adaptation.
>• Scatter requirements for an individual BMP throughout the manual. Instead, develop individual fact sheets for each BMP that
identify all the important selection, design, construction, and maintenance information.
Present Stormwater management criteria and design requirements without providing corresponding design methodologies
and documentation.
>• Make the manual more than about 2 inches thick.
Ignore the input and comments from the local Stormwater design and development community.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.12. Directory of State and Local Stormwater Manuals Reviewed
State Manuals
Alabama
Alaska
British Columbia
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Guam
Idaho
Illinois
Iowa
Kansas
Kentucky
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Nevada
New Hampshire
New Jersey
New York
North Carolina
North Dakota
Northern Mariana Islands
Ohio
Ontario
Oregon
Alabama Handbook for Erosion Control, Sediment Control and Stormwater Management on
Construction Sites and Urban Areas
Alaska Stormwater Pollution Prevention Plan Guide
Stormwater Planning: A Guidebook for British Columbia
New Development and Redevelopment Stormwater Best Management Practice Handbook
Erosion Control and Stormwater Quality Guide
2004 Connecticut Stormwater Manual
Green Technology: The Delaware Urban Runoff Management Approach
Stormwater Management Guidebook
Florida Development Manual: A Guide to Sound Land and Water Management
Georgia Stormwater Management Manual
Northern Mariana Islands and Guam Stormwater Management Manual
Catalog of Stormwater BMPs for Idaho Cities and Counties
Illinois Urban Manual
Iowa Stormwater Management Manual
Protecting Water Quality: A Field Guide to Erosion, Sediment and Stormwater Best
Management Practices for Development Sites in Missouri and Kansas
Best Management Practices (BMPs) for Controlling Erosion, Sediment, and Pollutant Runoff
from Construction Sites: Planning and Technical Specifications Manual
Stormwater Management for Maine
Maryland Stormwater Design Manual
Stormwater Management Handbook
Guidebook of Best Management Practices for Michigan Watersheds
The Minnesota Stormwater Manual
Planning and Design Manual for the Control of Erosion, Sediment, and Stormwater
Protecting Water Quality: A Field Guide to Erosion, Sediment and Stormwater Best
Management Practices for Development Sites in Missouri and Kansas
Handbook of Best Management Practices
Innovative Stormwater Treatment Technologies Best Management Practices Manual
New Jersey Stormwater Best Management Practices Manual
New York State Stormwater Management Design Manual
Draft Manual of Stormwater Best Management Practices
A Guide to Temporary Erosion Control Measures for Contractors, Designers and Inspectors
Handbook of Best Management Practices
Northern Mariana Islands and Guam Stormwater Management Manual
Rainwater and Land Development Manual
Stormwater Management Planning and Design Manual
Bio filters for Stormwater Discharge Pollution Removal
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.12. Directory of State and Local Stormwater Manuals Reviewed (continued)
State Manuals
Pennsylvania
Rhode Island
South Carolina
Tennessee
Vermont
Virginia
Washington
Washington
West Virginia
Wisconsin
Wyoming
Stormwater Best Management Practices Manual
Rhode Island Stormwater Design & Installation Standards Manual
South Carolina Stormwater Management and Sediment Control Handbook for Land
Disturbing Activities
Erosion and Sediment Control Handbook
Vermont Stormwater Management Manual
Virginia Stormwater Management Handbook
Stormwater Management Manual for Eastern Washington
Stormwater Management Manual for Western Washington
West Virginia Erosion and Sediment Control Best Management Practice Manual
Wisconsin Stormwater Manual
Urban Best Management Practices for Nonpoint Source Pollution
Local Manuals
Albemarle County, Virginia
Austin, Texas
Austin, Texas
Baltimore, Maryland
Columbus, Ohio
Dane County, Wisconsin
Design Standards Manual
Drainage Criteria Technical Manual
Environmental Criteria Technical Manual
Baltimore City Stormwater Management Manual
Stormwater Drainage Manual
Dane County Erosion Control and Stormwater Management Manual
Urban Drainage and Flood Control Urban Storm Drainage Criteria Manual
District (Denver, Colorado)
Eugene, Oregon
Kansas City Metro Area
Knoxville, Tennessee
Knoxville, Tennessee
Lake County, Illinois
Lake County, Ohio
Lexington-Fayette County,
Kentucky
Los Angeles, California
Philadelphia, Pennsylvania
Portland, Oregon
North Central Texas Council of
Governments
San Diego, California
Stafford County, Virginia
Stormwater Management Manual
Best Management Practices for Stormwater Quality
Land Development Manual
BMP Manual
Technical Reference Manual
Bioretention Guidance Manual
Stormwater Manual
Development BMP Handbook
Stormwater Management Guidance Manual
Stormwater Management Manual
Design Manual for Site Development
Land Development Manual
Stormwater Management Design Manual
Note: See Stormwater Manual Internet Directory in Tool 5.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.13. Summary of the Manual Building Tool
Topic Areas for Design Manual
Topic Areas for Policy and Procedures Manual
*• Stormwater Management Criteria
- Stable Conveyance/Channel Protection
- Flood Control
- Groundwater Recharge
- Water Quality
>• Special Criteria for Sensitive Receiving Waters
- Groundwater Protection
- Surface Water Protection
- Trout Stream Protection
- Wetland Protection
- Site-Based Pollutant Load Reduction
>• Special Criteria forTricky Development Situations
- Ultra-Urban/Small Site Practices
Pollution Source Control/Hotspot Management
>• Smart Growth
Low-Impact Development
>• BMP Selection Matrices
BMP Fact Sheets
>• Detailed BMP Design/Performance Specifications
- Bioretention
- Filtration
- Infiltration
- Open Channels
- Stormwater Ponds
- Stormwater Wetlands
- Green Rooftops
- Porous Pavement
- Rain Barrels
- Rain Gardens
- Experimental/Proprietary BMPs
>• Hydrologic and Hydraulic Models
Design Examples
>• Stormwater Credits
Detailed Landscaping Guidance
Detailed BMP Operation and Maintenance Requirements
>• Karst Topography
>• Arid/Semi-Arid Climate
>• Cold Climate
>• Ordinance Applicability
- Redevelopment Criteria
- Single-Family Lot Criteria
Application/Submittal Requirements
Plan Review Process
Plan Review Checklists
Permit Coordination
Maintenance Agreements and Plans
>• Deeds of Easement
>• Performance Bonds
>• Waiver/Fee-in-Lieu Programs
Construction Inspection Procedures
>• Construction Inspection Checklists
Maintenance Inspection Procedures
>• Maintenance Inspection Checklists
Violations, Enforcement and Penalties
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Chapter 6: Developing Stormwater Guidance Manuals
6.12. Tips for Stormwater Guidance Manual
Project Management
Scoping And Budgeting for the Manual
This section provides some insights on how a storm-
water manager can most effectively scope, budget,
and schedule the manual-building and adoption pro-
cess. In general, the basic steps in the manual-building
process consist of:
1. Scoping the Manual (see Section 6.4)
2. Outlining the Manual (see Sections 6.5 and 6.6)
3. Building the Manual (see Sections 6.7 through 6.11)
Policy and Procedures Manual
Design Manual
4. Collecting Input from Stakeholders
5. Adopting the Manual
6. Training Designers and Plan Reviewers on the
Manual
7. Maintaining and Updating the Manual
Since Steps 1 through 3 of the manual building process
were detailed earlier in this chapter, this section gener-
ally addresses the subsequent steps. However, one key
decision that affects the entire manual-building pro-
cess is determining which steps can be done in-house
and which can be assigned to a consultant or subcon-
tractor. The total effort is obviously tied to whether
the Stormwater guidance manual must be built from
scratch or whether an existing state or regional manual
can be adopted as a reference.
Table 6.14 provides some general estimates of the
staff time and estimated time frame needed to com-
plete each step in the manual-building process, using
several assumptions.
In most cases, the manual-building effort will be a
blend of in-house labor and contracting effort. The
pros and cons of using either form of labor are com-
pared in Table 6.15. Some tips on getting the most out
of a Stormwater consultant are presented in Table 6.16.
Maintaining and Updating the Manual
Experience has shown that the first edition of a new
Stormwater guidance manual is never perfect; errata,
clarifications, and policy interpretations are needed
from day one. Stormwater managers should always
budget some time and money to maintain and update
the manual. Changes can be made efficiently if the man-
uals are posted on the Web (but make sure to number
and date each new release). It is also helpful to maintain
a user e-mail database so that Stormwater managers
can quickly notify users about any new releases.
It is recommended that communities update their
Stormwater manuals at least once every 5 years. This
update should include full stakeholder input and focus
on improving the effectiveness of the Stormwater
management program. Also, language in the storm-
water ordinance should provide reference to "the most
recent version" of the manual so that updated material
in the manual is covered by the ordinance.
6.13. Involving the Public in Developing the
Stormwater Guidance Manual
This section provides information on involving stake-
holders in the Stormwater manual development process,
as well as training both design consultants and plan
reviewers on use of the manual once it is developed.
Involving Stakeholders in the Manual-building
Process
Because the Stormwater guidance manual will be used
by the local design community, the manual-building
process offers an excellent opportunity to engage this
community. Local design consultants, provided that
they are familiar with the concepts presented in the
manual, can contribute information on what works
and doesn't work and give practical insight into the
selection and design of Stormwater BMPs. Often these
discussions can be very productive and can help build
a more effective manual.
The manual-building process is also an opportunity to
engage other stakeholders by inviting their input and
providing them with insight into the local Stormwater
approach. It can be helpful to expand the stakeholder
group to include interests outside the local design
community to get a broader level of input and
additional opinions on important policy decisions.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.14. Projected Staff Effort for Each Step of the Manual-Writing Cyclea
Manual Building Step
1. Scoping the Manual
a) Manual scoping
b) Scope of work
c) Contracting process
2. Policy and Procedures Manual
a) No procedures exist
b) Need to add a few
c) Mmost already exist
3. Engineering Design Manual
a) Start from scratch
b) Major supplement
c) Minor supplement
4. Stakeholder Input
a) Tech committee
b) Expanded input
5. Manual Adoption
Estimated Staff Effort e
(days)
5 to 8 days
3 to 5 days
5 to 10 days
30 to 60 days
10 to 15 days
5 to 8 days
150 to 250 days
50 to 100 days
10 to 25 days
15 to 30 days c
Varies
10 to 15 days
Time Frame to Complete
(weeks)
1 to 3 weeks
2 to 3 weeks
4 to 12 weeks
12 to 24 weeks b
8 to 12 weeks b
4 to 8 weeks b
24 to 72 weeks
12 to 36 weeks
12 to 24 weeks
12 to 24 weeks
Varies
13 to 26 weeks
6. Manual Training
15 to 30 days1
12 to 24 weeks
7. Manual Maintenance
a) Initial revision
b) Overhaul during permit
10 to 20 days
25 to 40 days
2 to 4 weeks
12 to 36 weeks
Notes and Assumptions
a These projections are illustrative only and should be carefully checked.
b Time frame may expand if review by municipal attorney is needed.
c Assumes an average of 30 hours staff time per meeting.
d Assumes 40 hours per training session.
e To get probable consultant cost, convert days to hours and multiply hours by a $100 to $125 hourly rate.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.15. Pros and Cons of Using In-House and Consultant Labor to Build a Stormwater Management Guidance
Manual
In-HouseLabor
Consultant Labor
Pros
Often less expensive
Ensures greater ownership and understanding
Can tailor to particular local project review process
>• Can tailor to local high-value water resources
Potential to create a comprehensive and professional-looking
manual
Can bring outside expertise/resources to bear
Can get it done faster
Can be perceived as more objective by stakeholders
Cons
>• Will take longer to complete
>• Regular responsibilities of staff make it difficult to
complete
>• Staff may not have necessary expertise
>• Professional-looking graphics (e.g., CADD) may be hard
to produce
No municipal ownership of manual after contract is over
>• Contracting process can add significant cost to project
>• Local firms may not have necessary expertise
Can be difficult to keep updated if text and graphics are in
complicated format
Table 6.16. Getting the Most from a Manual Consultant
>• Askthe scoping questions in Section 6.4 to define the manual content before developing a scope of work.
Use the scope of work to define specifically what you want in your manual before you approach a consultant.
Determine which tasks are cheaper to do in-house (meeting logistics, inviting stakeholders, coordinating review comments,
compiling the project review manual).
Beware of scope creep. It is better to ask for less and get good quality than to ask for the Cadillac version that exceeds
available budget.
Remember that a lot of meetings and manual revisions will be needed. Make sure you get cost estimates for each.
Use the consultant to research current options for BMPs and approaches you are not familiar with.
>• Think a bout requiring a double consultant team—a local consultant that is thoroughly familiar with the existing
development review process and local Stormwater BMPs and a non-local consultant that has demonstrated experience with
Stormwater designs not currently used in the community.
If a combination of in-house and consultant labor is used, make sure to assign a single person to coordinate the team effort
between the agency and consultant, and make roles and responsibilities clear in the scope of work.
>• Strive for a multidisciplinary team (in-house and consultant) with experience in engineering, regional planning, landscape
architecture/horticulture, soils and geology, and other disciplines relevant to the Stormwater BMPs you want to include in the
manual.
Use a technical or stakeholder committee to give structured input and feedback to the consultant, but make sure the input is
compiled and organized clearly by the in-house project manager.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.17 presents a list of key stakeholders who
should be involved in the manual-building process.
Table 6.17. Key Local Stakeholders to Involve in the
Manual-Building Process
Consulting engineers
Local engineering
associations
Contractors
Developers
Homebuilders
Watershed groups
Smart Growth groups
Plan reviewers and
inspectors
Wetland regulators
Landscape architects
Public health authorities
(re. mosquitoes)
Local road/highway
engineers
Surveyors
Homeowner associations
Economic development
agencies
A range of methods can be used to solicit input from
stakeholders during the manual-building process:
• Technical review committee: The most traditional
method is to assemble a group of stormwater
stakeholders to provide input on the scope of the
local stormwater manual and to review various
drafts as the manual is written. The group can serve
as a "standing committee" to help with training
and in updating the manual in the future. The
committee approach can be quite time-intensive,
and it often requires multiple meetings before final
consensus is achieved.
Focus groups: This approach seeks to gain input
from a select group of experts or stakeholders
during a one-time meeting to gauge reaction to
proposed manual approaches and key stormwater
issues.
Field trips, outreach events, workshops: A dose
of stormwater education is often helpful to get
stakeholders to understand stormwater issues and
practices. These events are experiential, visual, and
interactive, and they help the group get a first-hand
look at both stormwater problems and solutions.
• Stormwater site tours and visual tours: Many
stakeholders are hesitant to accept new stormwater
BMPs if they have not yet been applied in the
community. This reluctance can be overcome
by arranging tours in other communities where
innovative practices have been effectively used.
A more low-cost approach is to develop a visual
tour using PowerPoint slideshows of innovative
practices from other communities or regions. Check
the Center for Watershed Protection's Stormwater
Center Web site for an extensive catalog of
stormwater images (www.stormwatercenter.net).
• Demonstration BMPs in New Municipal
Construction: Localities may consider
demonstrating innovative practices in municipal
construction projects as a strategy to gain greater
acceptance. This approach of leading by example
can help overcome barriers to practice adoption.
• Public Meetings and Hearings: These formal
settings might be required to give notice, accept
comments, or present testimony to formally adopt
the manuals. Stormwater managers should not rely
solely on these formal meetings to get stakeholder
input (since they are customarily held near the
end of the rule-making process). Instead, they
should consider investing in some of the informal
stormwater education methods mentioned above.
Table 6.18 presents some helpful tips aimed at assist-
ing stormwater managers in collecting useful input
from stakeholders and making the most of the stake-
holder input process.
Training Designers and Plan Reviewers
Many communities get so involved in building the
stormwater manual that they are too exhausted or
cash-strapped to train their own plan reviewers and
engineers on how to actually use it. At the same time,
design consultants are notoriously busy and will be
sacrificing billable time to learn the information in
the manual. Communities will need to allocate time
for training plan reviewers and design consultants.
Otherwise, municipal staff will end up training design
consultants on a piecemeal basis during every plan
submittal. Training is a sound investment because it
can help reduce future plan review time and result
in fewer resubmittals. Table 6.19 outlines some tips
on designing effective training programs for the new
stormwater manual.
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Chapter 6: Developing Stormwater Guidance Manuals
Table 6.18. Tips for Making the Most of the Stakeholder Input Process
>• Keep an up-to-date mailing and notification list for the regulated community (e.g., developers and designers).
Develop technical support documents or issue papers to support design decisions.
>• "Sell" the environmental and economic benefits of new Stormwater approaches.
>• Use demonstration sites at municipal facilities to "show off" innovative practices and desired approaches.
>• Post manual drafts and technical committee comments on the agency Website so they can be easily accessed.
>• Be open to change throughout the manual-writing process.
>• Carefully log all comments received and track how each one was handled, and make this record available to stakeholders.
Develop and communicate clear procedures for keeping the manual updated.
Make sure to recognize the volunteer efforts of Stormwater stakeholders who participate in the manual review process.
Communicate clearly to decision-makers the intent of the manual to aid compliance (and not to impose additional
requirements).
Table 6.19. Tips for Effective Manual Training
Start with your own plan review and inspection staff. They are the core group that will end up training much of the local
design community.
Provide incentives for designers to attend training sessions, and indicate how attending the training can get their plans
approved more quickly and with fewer revisions.
Conduct short training work sessions at convenient times for the busy professional.
>• Use real development sites for design examples.
>• Clearly specify what's new and different in the manual.
Train consultants in new modeling techniques.
Administer multiple-choice tests to measure proficiency with the manual.
Always ask stakeholders what their training needs are, and incorporate their responses into the next training.
>• Recognize innovative local designers and include them in the training program.
>• Focus on the practices you really want to promote.
>• Provide opportunity to discuss Stormwater issues and policies that are not contained in the new manual.
>• Get feedback to improve future training sessions.
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Chapter /
The Stormwater Plan
Review Process
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 9
Maintenance
Program
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 3
Linking Stormwater to
Land Use
Chapter 4
Stormwater Approach
& Criteria
Chapter 5
Post-Construction
Ordinance
Chapter 6
Stormwater Guidance
Manual
Plan Review, BMP
Construction & Maintenance
Checklist
Companion Tools for Chapter 7s
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
Current trends and issues with Stormwater plan
review
Scoping out the best review process for a local
Stormwater program
The anatomy of a typical Stormwater plan review
process
Tips for building an effective Stormwater plan
review process
Involving the public in development review
Managing Stormwater in Your Community
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Chapter 7: The Stormwater Plan Review Process
7.1. Introduction
Previous chapters covered program planning, adopt-
ing a stormwater ordinance, and developing a storm-
water guidance manual. The next step is to have a
plan review process that ensures that the stormwater
standards and specifications are translated correctly
onto development plans.
Approval of a stormwater plan is an important mile-
stone. After plans are approved, making changes to the
situation "on the ground" can be very difficult. There-
fore, the plan review and approval process is the best
opportunity to get things right with stormwater design.
A well-organized stormwater plan review process can
help ensure that:
Stormwater BMP designs meet the standards and
specifications in the ordinance and design manual
and are being properly applied to the project site.
• Stormwater plans incorporate innovative practices,
such as site design techniques and low-impact
development, early in the planning process.
BMPs are sited within easements and have adequate
access for inspection and maintenance.
• Adequate maintenance agreements that assign
long-term maintenance responsibility are in place.
The stormwater BMP plan approval is coordinated
with other necessary environmental permits for
erosion and sediment control, streams, wetlands,
floodplains, and dams.
• Approved stormwater BMPs are covered by
performance bonds to ensure proper installation in
the field.
The location and specifications of approved
stormwater BMPs are properly documented at each
site so that inspection and maintenance staff will
have the necessary information.
The review process generates the appropriate
amount of user fees to help defray development
review costs.
Although requiring water quality BMPs on devel-
opment projects may be a relatively new function
within a local agency, most local governments
have experience with general development plan
review. A stormwater plan review process does not
have to be created from scratch. The biggest chal-
lenges are securing an adequate and well-trained staff
and integrating stormwater reviews with other local
reviews for drainage, utilities, erosion control, roads,
and site layout.
This chapter provides practical guidance for build-
ing a stormwater plan review process. The chapter
addresses:
Current trends and issues with stormwater plan
review
• Scoping out the best review process for a local
program
The anatomy of a typical review process
Tips for building an effective process
• Involving the public in stormwater plan review
7.2. Current Trends and Issues with Stormwater
Plan Review
The number of stormwater plans reviewed by a local
program on an annual basis ranges from fewer than
10 to more than 1,000 (CWP, 2006). The actual number
could be higher when all resubmissions are included.
The true test of "plan burden" is how many plans are
assigned to each reviewer. Many programs do not have
enough staff to conduct a thorough review of all the
plans submitted. The majority of programs have fewer
than 1.5 full-time employees (FTEs) assigned to the
review of stormwater plans. In addition, many of these
reviewers must also review other types of plans, such
as erosion control and road plans.
The number of plans each FTE reviews on an annual
basis ranges from around 15 to over 200, with the aver-
age reviewer checking from 70 to 100 plans per year
(CWP, 2006). Some local programs use consultants to
review stormwater plans; the review fees are paid by
the applicant.
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Chapter 7: The Stormwater Plan Review Process
7.3. Getting Started: Scoping the Stormwater
Plan Review Program
The first task in building or retooling a program to
review Stormwater plans is to scope out what changes
must be made in the existing Stormwater management
program and what additional components are necess-
ary. A list of scoping questions is provided below to
assist Stormwater managers in making these decisions.
1. What level of integration is desired between
Stormwater and other local reviews?
The question pertains to whether Stormwater plan
reviews should be conducted by a special agency,
often outside the usual development review
department. On the one hand, having Stormwater
reviews performed by an engineering or public
works department (often external to the planning
or community development office) can allow the
Stormwater review to be performed by a technically
trained, engaged Stormwater professional. On the
other hand, this type of segregation between site
plan and Stormwater reviews can make it difficult
to consider Stormwater design early enough in
the development process because the Stormwater
review may become a sidebar at the final plan stage.
This type of segregation is particularly problematic
if the program wishes to promote low-impact
development and/or Stormwater credits (see
Chapter 6), which require a link to early design
decisions.
2. Based on the expected plan load, what will be the
likely distribution between large sites, small sites,
redevelopment, and single-family lots?
If the program staff knows the types of plans
that it will receive, a better match can be made
between staff resources and the types of plan
review conducted. For instance, large, sophisticated
projects with complex computation packages will
likely require review by an engineer or someone
under the close supervision of an engineer.
Alternatively, single-family lot plans and small
commercial sites can be reviewed by a competent
(and trained) engineering or planning technician.
3. What is the current level of Stormwater knowledge
and training among plan reviewers and design
consultants in the community?
If Stormwater is new and unfamiliar to the review
staff and consultants, the program staff will have
to spend more time on education and training on
basics (e.g., sources of pollution, runoff calculations)
and specifics (e.g., particular BMP specifications).
4. How will the program balance plan review with
inspection and maintenance responsibilities in
terms of program staff and resources?
Plan review demands can overwhelm a local
program, consuming staff time to the point where
the program is unable to provide adequate services
for inspection and maintenance. Even a well-crafted
and reviewed plan means little if it is not followed in
the field. Local Stormwater managers should strive
for a balance between desktop review and field
inspections.
5. What is the level of citizen interest in and concern
about development in the community?
Many state and local laws require public access to
information, and the Phase II MS4 requirements
include public involvement. The development
review process is a prime program element where
public involvement can and should be built in.
Neighboring property owners, citizens groups, and
other community interests will want to know what
plans have been submitted and how they are being
reviewed. If BMPs are allowed on or adjacent to
residential lots, citizens will want to know what they
are for, if they are temporary or permanent, and
whether they can be modified. Public involvement
during development review involves use of
appropriate technology, such as a Web-based
tracking system, and an attitude of openness within
the review agency.
7.4. The Anatomy of Stormwater Plan Review
Figure 7.1 outlines a generic plan review process for
Stormwater. Of course, particular local procedures vary
in complexity and the degree of interdepartmental
coordination. As depicted in the figure, the
Managing Stormwater in Your Community
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Chapter 7: The Stormwater Plan Review Process
Stormwater Authority
1 . Materials & Forms Made
Available to Regulated Community
"
4 A,
2. Pre-Submittal
Meeting
4. Submittal Accepted as Complete:
Review Initiated
3. Subm
Appli
4-
5. Review & Comment on
Concept Plan
±
7. Concept Plan Approval
9. Submittal Accepted as Complete:
Review Initiated
t
iterative 6. Resubmittc
4
^ 8. Submit F
Computation
i
10. Review & Comment on
Final/Design Plan
±
12. Coordinate with Other Internal
or Local Reviews
+
k
iterative II.Resubmitt
4
13. Verify All Applicable State/Federal Permits for
Work in Streams, Wetlands, and Floodplains
+
14. Maintenance Agreement Completed & Recorded
+
15. Performance Bond Calculated & Posted
V
16. Final/Design Plan Approved
i
17. Documentation/Tracking for Plat
Review, Inspections & Maintenance
iplicant
"^
t Concept Plan,
cation & Fee
) Address Comments
H
inal/Design Plan,
s, Application & Fee
o Address Comments
Figure 7.1. Typical Stormwater plan review process
Managing Stormwater in Your Community
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Chapter 7: The Stormwater Plan Review Process
department or agency that reviews stormwater plans
(the stormwater authority) is responsible for certain
actions, while other actions are the responsibility of the
developer/applicant or are a shared responsibility (those
that straddle the figure's centerline). Table 7.1 provides
a brief description of each step outlined in Figure 7.1.
Table 7.1. Brief Description of Tasks in Stormwater Review Flowchart
1.
2.
3.
4.
5.
6.
7.
8.
9.
Materials and Forms Made
Available to Regulated
Community
Pre-Submittal Meeting
Submit Concept Plan,
Application and Fee
Submittal Accepted as
Complete
Review and Comment on
Concept Plan
Resubmit to Address
Comments
Concept Plan Approval
Submit Final/Design Plan,
Computations, Application
and Fee
Submittal Accepted as
Complete
The regulated community needs to know what is expected. The following materials and
forms should be provided:
>• Submittal application and fee payment form
>• Review flowchart and schedule
>• Plan submittal and review checklists
>• Contact information for relevant personnel.
A pre-submittal meeting can be voluntary or mandatory, and it can be in the office or field. It
gives the applicant a chance to sit down with reviewers to scope out relevant questions and
can lead to better submittals and quicker compliance. It is also a critical step for plans that
use low-impact development (LID) or stormwater credits.
A Concept Plan provides the opportunity for the applicant to put basic stormwater design
ideas on paper, and it gives the reviewer something to react to before the applicant expends
the time and resources preparing more complex engineered plans and computations. Again,
this is a critical step for plans that use LID and stormwater credits. The stormwater reviewer
should coordinate with staff who might be reviewing other components of the site plan or
subdivision plat. Also, some preliminary computations (e.g., impervious area anticipated,
preliminary pre- and post-runoff volumes) are appropriate forthis stage.
Often, stormwater plans go through several unnecessary rounds of review because the
original application is not complete. The Stormwater Authority should ensure that elements
on the Concept Plan Checklist are submitted prior to initiating a formal review (see Tool 6:
Checklists).
The Stormwater Authority checks the Concept Plan to see if the proposed design is adequate,
so that the final plan can comply with the standards. Critical items to check a re whether the
proposed number, type, and approximate size of practices are adequate; whether critical
areas (wetlands, floodplains, streams) are identified and protected according to standards;
and whether other permits (e.g., wetlands) are likely to be required. If the program allows or
encourages low-impact development or nonstructural credits (see Chapter 6), the Concept
Plan should be used to identify which stormwater credits will be used in particular locations.
As shown in Figure 7.1, the comment and resubmittal process is iterative. Ideally, it can be
accomplished in two rounds or less for the Concept Plan stage (two submittals and two
reviews).
The Stormwater Authority should take some type of formal action on the Concept Plan, so
that all parties know that it is time to proceed to final Design Plan.
The Design Plan customarily includes a project narrative, plans, all necessary computations,
and other permit documentation (i.e., certification statement, professional engineers stamp,
proof of other permits). Based on the ordinance, a fee is collected for the initial submittal
and/or for each resubmittal and review.
Again, the Stormwater Authority should check the plan against the Design Plan checklist to
verify that it is complete prior to initiating review.
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Chapter 7: The Stormwater Plan Review Process
Table 7.1. Brief Description of Tasks in Stormwater Review Flowchart (continued)
10. Review & Comment on Final/
Design Plan
This is a detailed review to verify compliance with all standards in the ordinance and design
manual. Critical elements are computations, proper sizing and locating of BMPs, materials
and specifications, protection of critical areas, and coordination with erosion and sediment
control plans.
11. Resubmit to Address
Comments
This step is, again, an iterative process. Two rounds should be sufficient for most Design
Plan reviews, especially if the Concept Plan successfully establishes basic, agreed-upon
parameters for the design.
12. Coordinate with Other Internal
or Local Reviews
Coordination with other reviews and/or departments should be ongoing so that Stormwater
BMP designs, LID, and Stormwater credits can be considered early in the review process and
not as an afterthought once all road alignment, lot layout, and utility decisions have been
made on the site or subdivision plan.
Table 7.2 lists the other local permits and plans that typically must be coordinated with
Stormwater plans.
13. Verify Applicable State &
Federal Permits
Often multiple agencies are looking at the same site plan for different reasons, and in many
cases there are no formal means to coordinate the various reviews. For instance, if the Army
Corps of Engineers has jurisdiction over a stream or wetland that is proposed to be affected
by the plan, the Stormwater Authority should make sure that the Corps is in the loop while
reviewing the Stormwater plan. Table 7.2 lists typical state and federal permits that should
be coordinated with local Stormwater plans. The applicant should be responsible for
furnishing relevant documentation to show compliance with these various permit programs.
14. Maintenance Agreement
Completed & Recorded
A maintenance agreement obligates the responsible party to ongoing maintenance of BMPs,
and it should be recorded with the property deeds. The responsibility for the maintenance
agreement is often shared, with the applicant filling out and signing the agreement and the
Stormwater Authority making sure that it is recorded at the courthouse.
15. Performance Bond Calculated
& Posted
A performance bond or surety is posted to provide a financial guarantee that the BMPs on
the erosion and sediment control and Stormwater plan are actually installed in the field (and
maintained fora certain duration). Most programs require that the bond be posted prior to
approval of the final plan. Programs differ on whether the bond amount is computed by the
applicant or the Stormwater Authority (see Tool 7: Performance Bonds).
16. Final/Design Plan Approval
This is often the last chance for the Stormwater Authority to have input into the design
before the start of project construction, and to confirm that maintenance agreements and
performance bonds are in place. The Stormwater Authority should provide written approval
and put an approval date and stamp on the plan.
17. Documentation/Tracking
Once the plan is approved, the project moves to the inspection phase to verify that BMPs on
the plan are installed correctly in the field. Proper and centralized documentation should be
provided so that inspectors—and ultimately the parties responsible for maintenance—can
locate the BMPs and understand their specifications without having to dig through multiple
file drawers or work through numerous departments. See Table 7.3 for a description of
adequate documentation. Many localities have developed electronic or CIS-based tracking
systems to assist with geo-locating BMPs and tracking inspection findings, enforcement
actions, etc.
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Chapter 7: The Stormwater Plan Review Process
Table 7.2. Typical Local, State, and Federal Plans and Permits that Should Be Coordinated with Review of
Stormwater Plans
Local Permits/Plans
State/Federal Permits
>• Site plans and easement plats (showing drainage and
access easements)
Subdivision plats
>• Grading and drainage plans
Erosion and sediment control plans
Road plans
>• Floodplain permits
Well and septic permits, if applicable
NPDES (or state equivalent) construction Stormwater
permits (greater than 1 acre disturbed)
NPDES (or state equivalent) industrial Stormwater general
or individual permits
Army Corps of Engineers (section 404) and/or state
stream and wetland permits
Wellhead protection/source water permits
>• Dam safety permits
As mentioned in Step 17 of Table 7.1, adequate docu-
mentation should be prepared to transfer the project
to the inspection phase. Table 7.3 lists the documents
that constitute such a package.
Table 7.3. Documentation for Transferring Project
to Inspections and Maintenance
Project information: name of project, location, file or
tracking number, file location
>• Plan reviewer contact information
Information from Stormwater plan: number and type
of practices (structural and nonstructural), where they
are located, design computations, details,approved
as-built plans
Copy of any Stormwater credits applied to site
>• Copy of plat showing drainage and access easements
and any deeds of easement
Copy of recorded maintenance agreement denoting
responsible party
Maintenance plans approved as part of Stormwater
plan and/or maintenance agreement
Performance bond form and computation sheet (or link
to database)
>• Copy of other relevant permits (streams, wetlands,
floodplains, dam safety)
7.5. Tips for Building an Effective Stormwater
Plan Review Process
The following section provides eight tips for building a
more effective plan review process.
Tip #1 Start with "big picture" policy
decisions
As stated, most programs already conduct some type
of development review function, so may also have
a set of formal or informal policies in place. In some
cases, however, these policies are not well articulated
or communicated to the regulated community. Adding
Stormwater reviews to the existing review process can
be an opportunity to develop or clarify these policies.
Table 7.4 lists some pertinent policy considerations for
the Stormwater plan review process.
One particularly interesting option for development
review is to use consultants to review plans. Two pro-
grams polled as part of Stormwater program research
employ this strategy (CWP, 2006). Table 7.5 outlines
some of the pros and cons of using consultant reviews
based on the experience of these programs.
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Chapter 7: The Stormwater Plan Review Process
Table 7.4. Important Policy Questions for Stormwater Plan Review
How can the plan review process be structured so that Stormwater design is considered early in the review process? This is
particularly important for consideration of Smart Growth incentives, LID, and/or nonstructural Stormwater credits.
Should erosion and sediment control and post-construction Stormwater management plan reviews be combined?
Would the program benefit from contracting some or all Stormwater plan review functions to a private contractor?
>• What are appropriate schedules and goals for plan review turnaround times? What level of staffing is needed to accomplish this?
Will site visits by plan reviewers be conducted, and for which sites?
Will pre-submittal meetings be voluntary or mandatory?
If proprietary BMPs are accepted for use in the community, what guidelines or requirements will apply to approve their use
on a particular plan?
>• How will applicants and the public have access to plans and review comments?
>• What type and frequency of training are necessary to adequately educate plan reviewers and applicants?
>• Will field inspectors have any role in the plan review process, and plan reviewers in the inspection process?
>• How will public projects be reviewed? Should public projects be expected to lead by example?
Table 7.5. Trade-offs in Having Consultants Review Plans
PROS
CONS
Frees up local government staff for other tasks (e.g.,
program development, inspections, maintenance, master
planning).
>• Leverages highly skilled reviewers (e.g., P.E.s).
Additional staff is made available for high plan load times.
Responsiveness and turnaround time are generally very
good.
Deadlines are usually met.
>• Reviewers interact only with applicants, so political and
public pressure are reduced.
Consultant staff can't make policy decisions, so
coordination and communication with local staff can be
tricky.
Can be difficult for consultants to coordinate with other
local reviews early in the review process.
>• Review fees are variable and usually higher (based on
consultant time/fees for each plan).
There is a learning curve for applicants to get used to the
system.
Tip #2 Anticipate plan review load
According to Stormwater program research (CWP, 2006),
a typical reviewer's plan load is approximately 70 plans
per year. Individual reviewers who review more than 100
plans per year may have trouble providing a thorough
review and/or meeting review deadlines.
The ability of a local program to develop an efficient
and effective Stormwater plan review program is a
function of adequately anticipating the number of
plans that will be submitted, the complexity of the
plans (e.g., large sites with multiple practices versus
small, simpler sites). Large, complex plans can easily
take 8 hours for an initial review and 4 hours for each
resubmittal. Simpler and smaller sites can likely be
reviewed in 6 hours for the initial submittal and 2 to 4
hours for resubmittals.
A related factor is the turnaround time that must
be met for each review. The Stormwater ordinance
should have a basic review schedule; most allow 30 to
60 days for review of a submitted plan (after the plan
is accepted as complete). In addition, the leadership
of the agency might have unofficial goals related
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Chapter 7: The Stormwater Plan Review Process
to customer service that become de facto review
deadlines. Developers and design consultants will
always want the shortest turnaround time possible,
but it is preferable to set a realistic goal and meet
it than to promise a more ambitious schedule and
chronically fall short.
Once plan review loads are estimated, a program must
ensure an adequate level of staffing and develop an
outreach strategy so that reviewers and applicants
clearly understand the review process.
Tip #3 Develop forms and checklists for
reviewers and applicants
In the development review process, the main custom-
ers are the applicants that are submitting plans. A
smooth process will rely on providing clear instruc-
tions and managing expectations. Table 7.1 (Step 1)
provides some information on the types of forms that
are recommended to aid the submittal process. One
type of form that is sometimes overlooked is the fee
form. If a program is not collecting plan review fees, it
is missing out on a source of revenue that is generated
by the "users" rather than general taxpayers.
Another critical type of form is the plan review check-
list. Tool 6: Checklists provides plan checklists for both
concept plans and final design plans. These checklists
(or versions modified by individual programs) can be
provided to applicants to help with plan preparation.
Reviewers can also use them to verify that an initial
submittal is complete and ready for review.
Tool 6 also contains plan review checklists that
are specific to particular types of BMPs. Once the
reviewer verifies that all relevant information has been
submitted, the specific checklists can be used to help
review details and specifications on the plan. These
checklists address both structural and nonstructural
practices. The checklists can also be used as a sort of
routing slip if various reviewers are checking different
aspects of the same plan. Table 7.6 lists the BMPs
for which checklists are provided in the tool, and
Figure 7.2 illustrates the types of checklists included.
Table 7.6. Plan Review Checklists Provided in
Stormwater Checklist Tool
Structural Stormwater
BMPs
>• Bioretention
>• Filtration Systems
>• Infiltration Systems
>• Open Channels
>• Ponds
>• Wetlands
Nonstructural
Stormwater BMPs
>• Natural Area
Conservation and
Restoration
>• Sheetfiow to Buffer
>• Impervious Area
Disconnection
>• Grass Channels
Another area of variability and potential conflict
between reviewers and designers is the type and
format for computations. Reviewing design computa-
tions can be difficult when there is no standard format
and computations are submitted as stacks of computer
output. A standard computation submittal package
can help both applicants and reviewers know what is
expected. Table 7.7 outlines a recommended compu-
tation submittal package.
Tip #4 Hold Pre-Submittal Meetings
Even at the concept plan stage, the developer or
design consultant has spent a good deal of time
developing the site layout and even picking Stormwa-
ter BMPs. He or she might not be aware of site design
alternatives that could reduce both runoff and cost.
Also, the developer or design consultant might not
be aware of available Stormwater credits for LID or
nonstructural measures. The best way to communicate
this information early in the design process is through
a pre-submittal meeting (Figure 7.3). Often this is the
only meaningful way to introduce these concepts early
enough in the process to effect real design changes.
The pre-submittal meeting can be held in the office
or at the site, and it can be voluntary or mandatory,
depending on the preferences and capabilities of
the local program. Pre-submittal meetings are also
the appropriate time to communicate with appli-
cants about other relevant permits (e.g., construction
Stormwater, wetlands and streams, floodplain, dam
safety). The meeting can be used to promote the
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Chapter 7: The Stormwater Plan Review Process
Concept Plan Checklist
Project Plans
S = Satisfactory U = Un
Item S
1. Existing and proposed topography
(minimum 2-foot contours or local standard)
2. Existing and proposed stormwater
management system
a. Catchments
b. Drainaae areas & flowoaths
c. Stormwater management practices:
types identified and adequate surface
area allocated on clan
d. Proposed drainage and maintenance
access routes and easement locations
e. Stream reaches
f. Prooosed channel modifications
3. Predominant soil types
Existing land cover/land use and proposed
limits of disturbance
5. Resource protection areas (e.g. sensitive
streams, wetlands and lakes)
Final Design Plan
Checklist
esign Computations
• = Satisfactory U = Unsatis
Item
P re-development hydrologic/hydraulic
analysis (show methodology and supporting
calculations)
a. Drainaae areas and desian ooints
b. Land use, soil type and impervious
cover assumptions
c. Curve number assumptions
d. Flow oaths and times of concentration
e. Summarv of desian storms analyzed
f. Peak runoff rates
a. Total runoff volumes
2. Post-development hydrologic/hydraulic
analysis (show methodology and supporting
calculations)
Structural BMP
Plan Review
Checklist
|1. Type of facility (check all that apply)
a. Infiltration
b. Filtration
c. Bioretention
Item
d. Extended Detention (storage for Cpv,
On. Of)
|2. Facility Location
a. Surface
b. Underground
iltration Media
No filtration media (e.g. dry well)
Sand
Bioretention Soil
Peat
Other
Item
Type of conservation area
a. Forest
b. Prairie
c. Other
Nonstructural BMP Plan
Review
Checklist
A. Project Plans
Item
1. Plan view depicts the boundaries of the
conservation area relative to existing and
proposed features. And includes the
following:
a. Limits of existing natural area
b. Average slope of natural area
c. Root zones for specimen trees
d. Type, size, and condition of existing
vegetation
Figure 7.2. Tool 6: Checklists includes checklist tools for concept plans, final design plans,
structural BMPs, and nonstructural BMPs
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Chapter 7: The Stormwater Plan Review Process
Table 7.7. Recommended Computation Submittal Package (derived from Claytor, 2006)
Cover: Project title, client, nature of computations
Project vicinity map
>• Watershed delineation for pre- and post-development conditions with travel times (times of concentration), land use, and soils
Soils survey map
Narrative of Stormwater management system
>• Summary of hydrology and hydraulics
*• Table of drainage areas, curve numbers (CNs), time of concentration (Tc), peak discharges (pre-and post-construction) that
summarizes the performance of proposed Stormwater measures.
Detailed hydraulic calculations (hydraulic calculations of outlet orifice, weirs, spillways, etc.)
Hydrologic analyses (e.g., area CN calculation spreadsheets, practice sizing equations, model run outputs)
Other calculations (e.g., inflow channel sizing, outfall channel, downstream analyses, dam breach assessments, filter
diaphragm sizing, groundwater mounding analyses, structural calculations)
Site photographs
List of permit requirements and how project is in compliance (including permits needed for construction Stormwater, streams
and wetlands, floodplains, stream buffers, wellhead protection, and dam safety and other relevant permits)
Supporting data (as applicable)
- Soil test pits and/or borings
- Pollutant monitoring data
- Groundwater elevation data
- Habitat evaluations
- Tree surveys
- Threatened and endangered species
- Receiving water classification (e.g., 303(d) listing, cold-water fishery)
Figure 7.3. Hold a pre-submittal meeting to review Stormwater alternatives
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Chapter 7: The Stormwater Plan Review Process
idea of avoiding impacts on sensitive resources rather
than going through a lengthy permit process.
Finally, the pre-submittal meeting can be a time for
stormwater managers and land use planners to sit in
the same room with applicants and fully discuss the
idea of using site planning and Smart Growth tech-
niques to avoid stormwater impacts (see Chapter 3 for
more details on this topic).
Tip #5 Reward good actors
Plan reviewers and applicants are often in conflict
about the time it takes to review a particular submit-
tal. For most applicants, review time is a critical issue.
Therefore, incentives that incorporate expedited
reviews might be an attractive option. A lot of review
time is lost when a single plan must undergo multiple
submittals and reviews before the plan is deemed suf-
ficient. Some programs use submittal checklists and
standard runoff and water quality computation tables
as tools to promote expedited review. Plans that are
submitted with complete and accurate information are
moved to the top of the stack (especially resubmittals
of plans that have already been reviewed at least once).
Another justification for expedited review is to pro-
mote innovative practices, such as low-impact devel-
opment. Plans that go the extra mile and incorporate
design features that are encouraged by the local
program can be given priority review status.
Two important points attend to an expedited review
procedure: (1) ensure that the process is equitable and
that all applicants are eligible, and (2) make sure that
an expedited review is still a thorough review. Review-
ers must still have enough time to make sure that
all details and specifications are in accordance with
appropriate standards.
Tip #6 Provide training for reviewers and
design consultants
Both design consultants and local review staff typi-
cally work under the constant strain of deadlines. The
paradox is that without adequate training, the quality
of plan submittals decreases, the time needed for each
review increases, and the overall number of submit-
tals needed to get a single project through the process
increases. In the end, the available time is used less effi-
ciently than if the training were provided (Figure 7.4).
Chapter 6 provides some tips for training of design
consultants in the context of a design manual. Many of
these tips can be adapted for general training on the
development review process and can also be used to
train reviewers as well.
Figure 7.4. Provide training for plan reviewers and
design consultants
Tip #7 Set up a documentation and tracking
system
It is critical to track the receipt of plans, review com-
ments, resubmittals, approvals, maintenance agree-
ments, performance bonds, drainage easements on
plats, and the relationship between approval of a
stormwater plan and other internal approvals. If there
is an existing system for site plans and plats, investi-
gate whether stormwater plan tracking can be added
easily to the system.
Tracking plan submittals and reviews can help to
accomplish the following:
• Helps local stormwater managers keep track of
plans and workloads, and provides feedback on
review times and staffing needs.
• Allows applicants to track their submittals through
the process at any given time. Some programs
provide this information on the Internet.
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Chapter 7: The Stormwater Plan Review Process
Assists the program with reporting of measurable
goals in the MS4 permit. (For example, counting
plans and reviews is one of the easier metrics to
report; such a system can also help with public
involvement goals.)
• Allows the program to comply with record-keeping
and open government requirements.
Many localities, including the following, are shifting to
Web-based systems for tracking projects:
• City of Greensboro, North Carolina's online plan
tracking system (Figure 7.5):
http://www.ci.greensboro.nc.us/PlanReview
City of Omaha, Nebraska's online system for
construction inspections and citizen complaints:
http://www.pcwperosioncontrol.org/public
Chapter 10 provides additional information on general
stormwater tracking, monitoring, and evaluation.
Source:
www.ci.greensboro.nc.us/PlanReview/PlanSearchFull.asp
Figure 7.5. Example of Web-based plan review
tracking system from the City of
Greensboro, North Carolina
Tip #8 Integrate development review and
inspections
A field inspector "inherits" a plan from the reviewer, and
the two will likely have different perspectives about the
project. Inspectors can be quite good at anticipating
problems related to construction sequence, conflicts
with utilities, equipment access, and other issues that
can become problems in the field.
On the other hand, the inspector's job is to ensure that
the project is built to the specifications and details on
the plan, and the inspector might not have the leeway
or inclination to apply flexibility in certain circum-
stances. The reviewer might have a better sense of the
ultimate BMP design purpose and can help the inspec-
tor ensure that construction and installation meet that
purpose. The reviewer can also apply judgment about
when to notify the applicant's design consultant if field
modifications are necessary.
In short, the plan review process should allow for
two-way communication and coordination between
reviewers and inspectors. The following are several
simple strategies to enhance this coordination:
Invite inspectors to team review meeting for
individual plans.
• Have reviewers and inspectors attend the same
training, and include both design and construction
issues.
Have plan reviewers attend pre-construction
meetings for projects they reviewed.
• Encourage reviewers to periodically go on
inspection rounds with inspectors.
7.6. Involving the Public in Stormwater Plan
Review
Public involvement during stormwater review will
likely be tied to a broader public involvement and
notification process for development review in general.
This process is likely to have a nominal level of public
involvement built in through the formal notification
and public hearing requirements included in local or
state codes. However, stormwater managers should
strive for a public involvement process that goes
beyond minimum legal mandates. Public involvement
should add value to the process by incorporating a
broad set of ideas early in the review cycle. The process
should also aim to make stakeholders feel that their
input has meaning and is not collected as a mere
formality. The development review process is also an
excellent venue for incorporating public education
and outreach efforts that also fulfill MS4 requirements.
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Chapter 7: The Stormwater Plan Review Process
Table 7.8 lists stakeholders that are customarily
involved in the stormwater review process and various
strategies that can be incorporated into a meaningful
public involvement program. The table lists stake-
holder in different categories:
Primary stakeholders are those who are involved
directly in the review process for a particular
property, such as the applicant, the applicant's
design consultant, and adjacent property owners.
These parties often have the most to gain or lose
from the approval or disapproval of a plan.
Review process stakeholders are other departments
or agencies that have a role in reviewing the overall
development proposal (for environmental and
other compliance issues). Communication and
coordination with these stakeholders is important
to ensure an efficient process.
Other stakeholders are additional parties that
should be included in a transparent process.
These stakeholders might have general interest in
development issues within the neighborhood or
community, and they might wish to speak at public
hearings if given the opportunity.
Table 7.8. Key Stakeholders in Stormwater Development Review and Selected Strategies
Stakeholder Group
Public Involvement Strategies
Primary Stakeholders
>• Applicant
>• Applicant's design consultant
Adjacent property owners
>• Elected officials and/or planning boards that must
approve plans
>• Electronic orWeb-based plan and comment tracking and public
notification of plan status
>• Training and workshops on stormwater plan content, especially
information that may be new to the local community (e.g., LID,
stormwater credits)
Early notification and fact sheets for adjacent owners
Roundtable process to amend local codes to promote LID and
innovative practices (also include other stakeholders listed below)
Review Process Stakeholders
Planning department
Public health agency (well and septic approval)
>• Water and sewer utility
Floodplain administrator
>• Erosion control administrator
>• Zoning enforcement agency (standing water)
>• Local/state transportation department
>• Army Corps of Engineers
>• State/regional regulatory agencies (wetlands)
>• Parks/green way administrator
>• Training and workshops on stormwater, and on the role planners
have in reducing stormwater impacts by influencing design (e.g.,
reducing impervious cover)
>• Joint review meetings where various agencies can express their
views and concerns
>• Joint site visits with other departments/agencies
Cross-training with relevant departments
Other Stakeholders
>• Local environmental groups
Local builders'association
>• Property owners and residents in vicinity of
project
>• General public
>• Web-based system on review process and plans in the review mill
>• Public notification when waivers are granted
Fact sheets on BMPs and "urban legends" (e.g., mosquito breeding)
>• Community meetings for specific plans before they reach public
hearing stage
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Chapfc
Inspection of Permanent
Stormwater BMPs During
Construction
Chapter 1
Introduction &
Background
Chapter 2
Program
Development
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 3
Linking Stormwater to
Land Use
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Plan Review, BMP
Construction & Maintenance
Checklist
Companion Tools for Chapter 8
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
Current trends with inspection programs
Scoping out an effective local inspection program
The anatomy of a typical inspection process
Tips for building an effective inspection program
i Involving the public in the inspection process
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
8.1. Introduction
Previous chapters discussed program planning, adopt-
ing a stormwater ordinance, developing stormwater
design guidelines, and the plan review process. Each
chapter represents a building block of a local post-
construction stormwater management program.
The next important step for a local stormwater pro-
gram is to ensure that BMPs that are approved through
the plan review process are built correctly at the site.
This involves careful inspection of the BMP installation
process while site construction is taking place.
For the purposes of terminology, this chapter dis-
cusses the installation of permanent (post-construc-
tion) BMPs during site construction, with the goal of
having the permanent BMPs installed correctly and
becoming operational at the end of the construction
phase. This chapter does not address the broader issue
of construction stormwater (erosion and sediment
control) measures. Guidance on developing construc-
tion stormwater pollution prevention plans (SWPPPs)
is available from EPA (see Developing Your Stormwater
Pollution Prevention Plan: A Guide for Construction Sites
at http://www.epa.gov/npdes/swpppguide).
An effective construction inspection process can help
ensure that:
Stormwater BMPs are built according to approved
plans and specifications.
• Future maintenance needs of stormwater BMPs are
reduced to the greatest extent possible.
• Low-impact development techniques are properly
implemented. Areas of the site shown on the plan to
be preserved are not disturbed during construction
(including soils that should not be compacted).
Proper materials and construction techniques are
used.
This chapter provides practical guidance for building
an effective program to inspect permanent storm-
water BMPs during construction and ensure proper
installation by addressing:
Current trends with inspection programs
Scoping out an effective local inspection program
The anatomy of a typical inspection process
Tips for building an effective inspection program
Involving the public in the inspection process
8.2. General Status, Trends, and Issues with
Inspection of Permanent Stormwater BMPs
During Construction
Although most local stormwater programs conduct
some type of inspection during construction, many do
not adequately follow through to ensure that post-
construction BMPs are installed correctly (CWP, 2006).
A minority of programs use tools, such as performance
bonds and as-built plans, to ensure proper BMP
installation.
Many BMP failures are due to construction and
installation problems, and most can be avoided
through an enhanced inspection effort. As an example,
Figure 8.1 illustrates several construction-related
problems that might occur during the installation of
various bioretention BMPs.
8.3. Getting Started: Scoping Out a Program
to Inspect Stormwater BMPs During
Construction
The first task in building or retooling a program to
inspect post-construction stormwater BMPs during con-
struction is to make key decisions about the inspection
program. A list of scoping questions is provided below.
1. Does the department or agency already inspect
construction sites?
Many local programs already conduct some
form of inspection of stormwater BMPs during
construction. Of those that don't, many might
work with departments or agencies that already
conduct some type of inspection program at
active construction sites, whether for erosion
and sediment control (ESC), forest conservation,
wetland protection, or building inspection. If these
programs are already in place, a local stormwater
program might be able to integrate a stormwater
BMP construction inspection program into one of
them.
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Bioretention swale, installed too early during active
construction, has become clogged with sediment.
Bioretention area does not drain because of improper
soil media, soils compacted during installation,
and/or filter fabric under media.
Curb inlets to bioretention swale have eroded
because of improper sizing of stone.
High plant mortality has occurred because improper
species were substituted during construction.
Site runoff by-passes bioretention swale because of
small elevation changes during construction.
Some site runoff by-passes bioretention because
of inadequate slope of filter strip.
Figure 8.1. Common issues with installation of post-construction BMPs, using bioretention as an example
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
2. What is the current level of knowledge among
inspectors about the design and installation of post-
construction BMPs?
Regardless of whether municipal staff perform the
inspections or private inspections are authorized,
it is critical that the inspectors be adequately
trained in the proper design and installation
of all stormwater BMPs that might be used in
the community. The inspectors must not only
understand the specifications "on paper" but also
understand how they translate in the field. This
might require basic surveying and other field skills
(e.g., determining whether a detention pond is
being constructed at the proper elevation with the
correct slopes). Inspectors must be familiar with:
Material specifications for the BMPs
• Installation schedule for the BMPs
BMP construction or installation techniques
• BMP operation and maintenance requirements
The inspector should also have a working
knowledge of commonly used proprietary BMPs in
order to ascertain whether they are being installed
and used correctly.
3. How often will stormwater BMPs on active
construction sites need to be inspected?
The required inspection frequency for some
local programs might be determined by the
stormwater ordinance. Other programs might not
have formal requirements but might set goals for
how often they will inspect stormwater BMPs on
active construction sites (e.g., once every 2 weeks,
as triggered by construction milestones, and as
construction is completed).
4. Is there an existing tracking system for inspections
and enforcement actions that can be modified to
include the inspection of stormwater BMPs during
construction?
There should be a method for tracking the
inspections and enforcement actions taken so
that appropriate follow-up can be conducted. If a
system exists to track other types of construction
inspections (e.g., ESC inspections), that system can
be modified to include the inspection of post-
construction BMPs during construction. Tracking
the type and location of each post-construction
BMP installed is critical to assist in the inspection of
the BMPs during and after construction.
8.4. The Anatomy of a Program to Inspect
Stormwater BMPs During Construction
Figure 8.2 illustrates the basic process for inspecting
the installation of post-construction BMPs. Of course,
particular local requirements or guidelines could affect
the complexity of the process illustrated in the figure.
As depicted in the figure, the department or agency
charged with site inspections (the Stormwater Authority)
is responsible for certain actions, while other actions
are the responsibility of the applicant/contractor or are
a shared responsibility (those that straddle the figure's
centerline). Information and guidance for each step
identified in Figure 8.2 are provided in Table 8.1.
8.5. Tips for Developing an Effective Program
to Inspect Stormwater BMPs During
Installation
Once the stormwater manager has a good understand-
ing of the stormwater BMP inspection process, the
following eight tips can help establish an effective pro-
gram to inspect stormwater BMPs during construction.
Tl P #1 Determine Who the Site Inspectors
Will Be
The key consideration is to determine who will con-
duct the inspections. There are a number of legitimate
options for a local program to consider:
• Existing construction inspection staff (e.g., ESC,
building inspection staff)
• Plan review staff
Dedicated post-construction BMP inspection staff
• Contractors retained by the local program
Contractors or on-site representatives retained by
the owner/developer
Each is described in more detail below, and Table 8.2
outlines several pros and cons of each option.
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Stormwater Authority
1. Obtain Approved Plan
Review Files
2. Confirm that Performance Bond
Has Been Posted
3. Hold
Pre-Construction
Meeting
4. Conduct Routine Inspections—
Include Post-Construction Features
iterative
6. Ensure Site Conditions Are
Adequate to Install Permanent
(Post-Construction) BMPs
8. Conduct BMP Installation
Inspections at Critical Milestones
iterative
10. Confirm As-Built Plans
11. Release Performance Bond
for Work Completed.
Issue Certificate of Completion
12. Transfer
Project Documentation/Tracking
Information to Maintenance Staff
Applicant/Contractor
5. Site Construction
7. Install Permanent
(Post-Construction) BMPs
9. Prepare and Submit
As-Built Plans
Figure 8.2. Typical process for conducting inspections of post-construction BMPs during construction
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Table 8.1. Brief Description of Tasks in Construction Inspection Process Flowchart
1. Obtain Approved Plan
Review File
The approved plan review file should be obtained from the plan reviewers. The following materials
and information should be contained within the plan review file:
Summary of how the requirements of the local Stormwater ordinance are met
>• List of all BMPs (structural and nonstructural) to be used at the development site
>• Plan set illustrating the types, locations, and specifications of Stormwater BMPs used at the site
>• Permits
Contact information for contractors and design engineers
>• Construction schedule
2. Confirm That
Performance Bond
Has Been Posted
The applicant should post an adequate performance bond or surety before approval of the final
plan (see Chapter 7). Inspection staff should ensure that the bond has been posted before any
construction activities begin. For more information, see Tool 7: Performance Bonds.
3. Hold Pre-Construction
Meeting
A pre-construction meeting should be held prior to any construction activity. The meeting should
review the Stormwater BMPs to be installed, critical construction milestones, and the sequence of
construction. It is recommended that the following parties attend the meeting:
>• Owner/developer and/or representative
>• Site construction superintendent
>• Relevant construction contractors (e.g., grading)
>• Site plan reviewer
Stormwater BMP inspector
>• Erosion and sediment control inspector
4. Conduct Routine
Inspections—Include
Post-Construction
Features
Project site visits and inspections should be conducted according to an established inspection
schedule. These routine inspections can be conducted on a regular basis (e.g. weekly, biweekly) or at
important milestones.
Site inspections should ensure that post-construction features are accounted for during the
construction process. Examples include:
Riparian buffers and natural areas identified on the post-construction plan are not disturbed.
>• Areas/soils identified on the post-construction plan for infiltration (or bioretention) are not
disturbed or compacted, unless the plan's construction sequence allows for co-location of
construction and post-construction facilities (see Chapter 1 for more discussion on this topic).
Permanent BMPs are not installed or converted prematurely during active grading or before
drainage areas are stabilized.
>• Information about post-construction BMPs that involve individual lots is communicated to site
contractors, subcontractors, and lot builders.
5. Site Construction
See no. 4 above. The contractors should be aware of post-construction features that might need to
be protected during site work. Contractors should be aware of both structural and nonstructural
BMPs approved for the site.
6. Ensure Site Conditions
Are Adequate to
Install Permanent
(Post-Construction)
BMPs
Many post-construction BMPs cannot be installed until drainage areas are stabilized with vegetation.
Infiltration and bioretention facilities are particularly sensitive to sediment loads during construction.
Other post-construction BMPs, such as ponds, are likely to be converted from erosion control basins,
and conversion should take place only after the erosion control phase is complete.
The inspector must communicate clearly to the contractor about the timing and scheduling for the
installation of post-construction BMPs. This might take place as different phases of the project are
stabilized.
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Table 8.1. Brief Description of Tasks in Construction Inspection Process Flowchart (continued)
7. Install Permanent
(Post-Construction)
BMPs
Once site conditions are adequate, per the inspector's verbal or written communication, the
contractor should install the post-construction BMPs according to the approved plans and
specifications.
8. Conduct BMP
Installation
Inspections At Critical
Milestones
Although inspectors cannot be on-site during the entire BMP installation process, it is critical that
inspections take place at critical milestones. These milestones might include:
Grading for post-construction BMPs
Modifications to embankments, risers, and spillways
Construction of forebays or pretreatment cells
>• Placement of underdrain systems
Testing and installation of soil or filtering media
>• Planting, final grading, final stabilization
Tool 6: Checklists includes checklists that inspectors can use during the installation of structural
and nonstructural BMPs. It might be prudent to have inspectors sign off at key milestones before the
contractor proceeds with BMP installation.
9. Prepare & Submit
As-Built Plans
10. Confirm As-Built Plans
Once BMP installation is complete, as verified by the inspector, the applicant's design consultant
prepares an as-built plan for each Stormwater BMP based on actual site conditions. This plan can take
the form of a "red-lining" approved design plan to note any discrepancies. The design professional
also certifies that the constructed BMP meets or exceeds plan specifications. It is important for the
as-built plan to confirm:
>• Placement of BMPs within easements
>• Proper sizing, dimensions, and materials
>• Elevations of inlets, outlets, risers, embankments, etc.
>• Vegetation per the planting plan
>• Location of permanent access easements
The inspector and the plan reviewer both sign off on the as-built plan, and any discrepancies are
noted.
11. Release Performance Once the inspector has confirmed that the BMP is properly installed per the plans and specifications
and is in good working order, the relevant portion of the performance bond can be released. It is
prudent to wait approximately 60 days and/or after two storm events to release the bond to ensure
that vegetation is established and the BMP functions properly during storms. Upon release of the
bond, some programs also issue a certificate of completion, which provides good documentation
for both the owner/responsible party and the maintenance inspection staff that BMP installation is
complete.
Release Performance
Bond for Work
Completed. Issue
Certificate of
Completion
12. Transfer Project
Documentation/
Tracking Information
to Maintenance Staff
Once BMP installation is complete, the Stormwater program will begin the next phase of inspections.
These regular maintenance inspections may be conducted by construction inspection staff,
dedicated maintenance staff, or agents of the owner. See Chapter 9 for more information on
maintenance inspection requirements.
The following information should be provided to the maintenance inspection staff and the party
responsible for long-term maintenance during transfer of the project:
>• Approved as-built plans
>• Recorded maintenance agreement and plan
>• Construction photographs and map of photo stations
>• Construction plans
Design computations and any as-built modifications
>• Contact information for responsible maintenance party
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Table 8.2. Pros and Cons of Using Different Inspection Options
PROS
CONS
Using Existing Construction Inspection Staff
Efficient use of staff.
Helps with integration of minimum measures 4 and 5
(construction and post-construction Stormwater) for
MS4s.
Allows inspectors to stay with project through entire
construction cycle.
May stretch existing staff beyond their capabilities;
post-construction might not get adequate attention.
Inspection milestones for Stormwater and building construction
might not coincide.
Using Existing Plan Review Staff
>• Plan reviewers are familiar with BMP designs.
Reviewers can judge necessary field changes.
Deadlines for plan reviews may conflict with being on-site at
critical construction milestones.
Reviewers will always have less time to spend in the field
compared to inspectors.
Using Dedicated Post-Construction Inspection Staff
>• Inspectors can concentrate on post-construction
BMPs.
>• Best method to ensure proper BMP installations.
>• May be inefficient to have specialization of inspectors.
>• Requires additional communication and coordination
between inspectors with different responsibilities (e.g., ESC,
post-construction, building).
Using Contractors Retained by the Local Program
Frees up local government staff for other tasks,
>• Trained and certified inspectors can improve the
quality of inspections, especially if they also have
design experience.
>• Inspector observations are made independent of
political pressures.
Private inspectors do not have enforcement authority; local staff
will need to get involved in enforcement actions.
Private inspectors might have business relationship with
the developer or contractor, which might cause a conflict of
interest.
Coordination with other inspectors and plan reviewers is more
difficult.
Cost might be high for the local program, unless reimbursed by
inspection fees.
Using Contractors or On-Site Representatives Retained by the Owner/Developer
Frees up local government staff for other tasks.
>• Cost is born by the owner or developer.
Local program can concentrate on training and
certification.
Local government must still police and audit the work of on-site
representatives.
Quality of inspections might decline if on-site representative
is an employee of the developer or contractor, as opposed to a
qualified third-party contractor.
Local government must have clear-cut enforcement procedures
based on inspection reports.
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Using Existing Construction Inspection Staff
One option for local stormwater programs is to inte-
grate a post-construction BMP inspection program
with an existing construction inspection program.
Many local stormwater programs already have or work
with departments or agencies that already conduct
some type of inspection program at active construc-
tion sites, whether for ESC, forest conservation, or
wetland protection. These programs can be integrated
with a post-construction BMP inspection program to
maximize resources and staff time.
Other types of inspection staff, such as building
inspectors, could be used as well, but care must be
taken to ensure that they visit the site at the appropri-
ate times and are properly trained. The timing of build-
ing inspections might not necessarily coincide with the
need for inspection of post-construction BMPs
(i.e., stormwater BMPs might be in place before the
building of the structure begins).
Using Existing Plan Review Staff
Using plan review staff to conduct site inspections can
be a very effective way to ensure that the most viable
BMPs are approved and built according to correct
specifications. Plan review staff are usually familiar
with the BMP designs and should be able to determine
whether BMPs are being installed according to the
approved plans. They would also be best equipped
to request plan and design changes in the field if it
appears the approved design is no longer adequate.
However, this staffing integration option would involve
field work during construction for the engineers and
plan reviewers, and this might be an additional respon-
sibility and require more time per project.
Using Dedicated Post-Construction Inspection
Staff
If construction inspections are currently not conducted
in the community or are conducted by staff who are
unable to conduct additional inspections for post-
construction BMPs, dedicated staff might need to be
employed to perform this task. These staff members
might have other duties, but their primary focus would
be on the proper installation of post-construction BMPs.
This approach has some benefits: (1) the inspector can
focus on a single task while performing the inspections;
(2) the inspector is trained specifically regarding the
design and installation of post-construction BMPs; and
(3) follow-up and enforcement are easier if the inspec-
tor can concentrate on BMP installation as opposed to
multiple other issues at the site.
Using Contractors Retained by the Local
Program
An additional option for local stormwater programs is
to hire a contractor to perform inspections of post-con-
struction BMPs. These outside contractors function in
much the same way as dedicated construction inspec-
tion staff, but the local program contracts the work out
instead of hiring new staff members.
Using Contractors or On-Site Representatives
Retained by the Owner/Developer
Some programs require that the engineers who design
stormwater BMPs "self-inspect" their own BMPs during
construction. The design engineers should understand
the intent of the BMP design and be able to ascertain
whether the appropriate methods and specifications
are employed during installation of the BMP.
Another self-inspection option is to require a hired on-
site representative to inspect and report on BMP instal-
lation progress. This approach is used in ESC programs
around the country. In most cases, on-site representa-
tives should be third-party consultants retained by the
owner or developer. The certified inspector is required
to regularly inspect BMPs and certify in writing that
they are installed according to plans and specifications.
These reports are submitted to the stormwater pro-
gram and/or kept on-site for reviews during spot-check
inspections by the local program. The self-inspections
can be used as the sole method of inspection or as
a supplement to the stormwater program's regular
inspections.
It is important to note that self-inspections and third-
party inspections do not relieve stormwater program
staff of all inspection responsibilities. Under this
system, it is critical to have a training and certification
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
program to authorize the private parties who are
conducting inspections. The local program is also
responsible for policing the system, detecting abuses,
reviewing inspection reports, and conducting periodic
co-inspections to ensure appropriate performance
levels.
TIP #2 Anticipate Inspection Loads and
Staffing Requirements
The ability of a local stormwater program to conduct
effective inspections of stormwater BMPs during the
construction phase is a function of the number of proj-
ects being simultaneously constructed, the complexity
of each project (e.g., large development sites with mul-
tiple stormwater BMPs as opposed to small sites with
one or two stormwater BMPs), the technical compe-
tence of the inspectors, the number of inspectors, and
the enforcement tools available to each inspector.
As stated in Chapter 7, a typical stormwater program
can expect to review between 70 and 100 develop-
ment plans each year. This number, of course, is based
on the rate of development in a community and the
specific applicability of regulations contained in the
stormwater ordinance. Getting a good handle on this
number, and the size and scope of particular develop-
ments, allows the stormwater manager to project the
number of construction sites that will be active during
any given year. This projection allows for the allocation
of inspection staff and resources.
In addition, if there is a mandated inspection fre-
quency for stormwater BMPs during construction (e.g.,
every 2 weeks, at the inception and conclusion of the
project), this must be considered as well when deter-
mining the staff and resource needs for the program.
IIP #3 Develop Forms and Checklists for
Inspectors
Proper documentation is essential to track inspec-
tion findings, as-built confirmation, and enforcement
actions. Inspection checklists are crucial not only to
track findings but also to ensure that multiple inspec-
tors are performing consistent BMP reviews. It is also
recommended that the checklists be signed by the
inspector and the contractor's on-site representative
receiving the checklist at the time of the inspection.
Tool 6: Checklists provides inspection checklists for
structural and nonstructural BMPs. The checklists
provided in the tool are listed in Table 8.3 and shown
graphically in Figure 8.3.
Table 8.3. BMP Construction Checklists Provided in
Tool 6: Checklists
Structural
Stormwater BMPs
*• Bioretention
Filtration Systems
>• Infiltration Systems
*• Open Channels
^ Ponds
>• Wetlands
Nonstructural
Stormwater BMPs
>• Natural Area Conservation
and Restoration
>• Sheetflow to Buffer
>• Impervious Area
Disconnection
>• Grass Channels
Checklists can be in hard-copy format, with duplicates
provided to the contractor's on-site representative or
superintendant. Increasingly, however, local inspec-
tion programs are using portable devices or laptops
coupled with GPS technology to record inspection
findings. This can save time with reentering data from
field checklists into an inspection database.
TIP #4 Develop An Adequate Enforcement
Plan and Enforcement Tools for
Inspectors
Upon completion of an inspection, the developer and
contractor should be informed of the results of the
inspection and any corrections that need to be made.
The letter should include basic information (e.g., date
of inspection, people present during the inspection, a
copy of the inspection checklist), outline any repairs/
changes that need to be made, and state when any
changes/repairs need to completed. It is hoped that
the developer and contractor will respond promptly
to the letter; sometimes they will not. In these cases,
inspectors must have the legal authority to enforce
the requirements of the local stormwater program.
The inspection of post-construction BMPs during
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Installation of
Structural BMPs—
Example: Infiltration
& Bioretention
(excerpt)
Installation of Non-
Structural BMPs—
Example: Grass
Swales (excerpt)
If off-line facilify, flow diversion sfrucfure
insfalled accordinq fo plans
Prefreafmenf facilify insfalled according fo
approved plans
3. Inleffs) and inlef profecfion insfalled
4. Sfrucfural componenfs (e.g. foundafion,
walls) insfalled according fo plans
a.
Maferials fesfed per locah^ouimT^r^s
Liner insfalled correcfly, if applicable
6. Pilfer bed composifion, depfh and
insfallafion conforms fo approved plans and
7. Riser/ouflef sfrucfure insfalled correcflv
a. Locafion, dimensions and fype of riser
^ai^correcf
b. Riser equipped wifh removable frash
rack
c. Locafion, dimensions and fype of low
flow orifice are correcf
d. Low flow orifice insfalled correcfly and
adeouafelv profecfed from clogging
e. If a filfrafion sysfem, underdrain sysfem
insfalled correcflv
Emergency overflow sfrucfure/spillway
insfalled according fo plans
Item
After erosion and sediment controls are
removed, drainage area to grass channels
matches area shown on plans
Grass channels match the dimensions and
slopes shown on the plans.
Erosion control blanket or turf reinforcement
mat insfalled properly, if applicable
1. Topsoil mixture, soil amendments, and soil
compaction complies with plan
2. Vegetation complies with approved planting
plan and specifications
Figure 8.3. Tool 6: Checklists includes construction/installation checklists for structural and nonstructural BMPs
construction should not be added to an inspector's
workload without providing the inspector with
the necessary enforcement tools to implement the
program.
The enforcement mechanisms that are potentially avail-
able to a site inspector are numerous, but they must be
backed up by the local stormwater ordinance or other
applicable local codes and ordinances. (For example
enforcement language, see Tool 3: Model Stormwater
Ordinance.) Typical enforcement tools include:
• Inspection results summary form letter
• Violation "ticket book" with administrative (civil)
fines
Notice to comply
Notice of violation
• Stop work order
Summary of civil/criminal penalties
• Process for withholding release of performance
bond
• Process for withholding release of other approvals/
permits (e.g., occupancy permit)
An enforcement tool package can be included in the
policy and procedures manual (see Chapter 6) and
provided to site inspectors. Some tools will be forms or
letter templates; others will be information sheets that
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
summarize processes and procedures. For example,
a tool might describe the local program's civil and/or
criminal penalties or outline the process for withhold-
ing the release of performance bonds or other approv-
als and permits.
IIP #5 Use Inspectors to Confirm As-Built
Plans and Transfer the Project to the
Maintenance Inspection Staff
Although the acceptance of as-built plans is primar-
ily a plan reviewer function, construction inspectors
can play a key role in confirming the accuracy of
as-built plans and adding documentation to the file
that might be extremely useful for the maintenance
inspection staff who will ultimately inherit inspection
responsibilities.
As-built plans should be prepared by qualified
engineers and surveyors to verify that post-
construction BMPs have been installed according
to plans and specifications. Inspection staff should
confirm these as-built plans and take photographs
of as-built conditions. Doing so will provide useful
documentation and help answer questions when
future maintenance issues are identified (Figure 8.4).
In some programs, the staff that inspects post-con-
struction BMPs during construction is the same staff
that inspects them afterwards for maintenance pur-
poses. In other cases, different staff members, facility
owners, or private responsible parties are used to per-
form maintenance inspections. See Chapter 9 for more
information about BMP maintenance requirements.
A special case might exist when proprietary BMPs
are installed. When transferring these projects to the
maintenance program, some stormwater managers
require additional documentation beyond as-builts
to help ensure long-term maintenance. At this
stage, the local program can require verification of
maintenance contracts or a limited-duration (e.g.,
3 years) maintenance bond to jump-start actual
maintenance of these devices (especially if the designs
are maintenance-intensive).
DEEP ROCK DITCH
ALONG CONTOUR -
1.51 #57 STONE ON TOP
OF 0.5'#78 STONE.
CAPPED WITH RIVER STONE
UNDERDRAW GRAVEL
TO SAPROLITE (VARIABLE) -
#57 STONE
PEA GRAVEL (0.51)-#78
STONE
UNDERDRAIN PIPE TO DAYLIGHT @ 1 % SLOPE (MIN.) -
PERFORATED BELOW BIOFILTER; NON-PERFORATED TO DAYLIGHT
4--20 SLOT WELL SCREEN FOR PERFORATED SECTIONS SCHEDULE
40 PVC FOR NON-PERFORATED SECTIONS
SILT TRAP CONVERSION TO BIOFILTER
PROFILE
NTS
Figure 8.4. Construction inspectors should be involved in confirming as-built plans
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
IIP #6 Provide Training for Inspectors
Construction inspectors must possess the skills to
assess conditions that could impact stormwater qual-
ity, as well as the skills to assess the effectiveness of
BMPs. The stormwater manager should develop and
implement a stormwater BMP training program and
also take advantage of existing training offered at
the regional or state level. A training program should
address the following:
• Site construction sequencing
• Requirements and content of stormwater pollution
prevention plans (SWPPPs)
• Design and function of post-construction BMPs
(structural and nonstructural)
Material specifications
• BMP installation techniques and sequencing of
installation steps
• Confined space training, especially in communities
where there are numerous underground practices
Unique issues associated with proprietary devices
• Common pitfalls in construction that affect the
functioning of stormwater BMPs
Local, state, and federal regulations that require
post-construction stormwater management (e.g.,
NPDES regulations)
Inspection protocols/process, for both contractors
and agency staff
• Enforcement response plan and tools
Some stormwater programs are offering training
and certification for contractors as well as municipal
inspectors. This approach helps to ensure that contrac-
tors are installing and inspecting BMPs appropriately
to maintain compliance and are better able to commu-
nicate with agency inspection staff if there are compli-
ance problems.
TIP #7 Integrate Plan Review and Inspections
Plan review and construction inspection staff and
processes should be integrated to the greatest extent
possible. This integration will help to minimize conflicts
between the plan review and construction inspection
processes and maximize the benefits of both.
As described earlier, the construction inspector's job
is to ensure that the project is built according to the
specifications and details shown on the approved plan.
The inspector might not have the inclination or author-
ity to require changes in the field to account for unique
site characteristics and conditions. The plan reviewer
might have a better sense of the purpose of the BMP
design and its ultimate functionality and therefore can
help the inspector ensure that the construction of the
BMP is consistent with its purpose. The reviewer can
also apply judgment as to when to notify the develop-
er's engineer of needed design modifications based on
field conditions.
Integration should allow for communication and coor-
dination between the site inspectors and plan review-
ers (Figure 8.5). Table 8.4 lists several simple strategies
to enhance this coordination.
Figure 8.5. Co-inspections by construction inspectors
and plan reviewers can help resolve BMP
installation issues
Table 8.4. Methods to Integrate Construction
Inspections and Plan Review
>• Invite inspectors to team review meeting for individual
development plans.
Have reviewers and inspectors attend the same training,
and include both design and construction issues.
>• Have reviewers attend pre-construction meetings for
projects they reviewed.
>• Encourage reviewers to periodically go on inspection
rounds with inspectors.
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
8.6. Involving the Public in Stormwater BMP
Inspections
Often, the public is a critical component in the ESC
inspection process. People are well aware if mud is
being tracked on their street or if a silt fence is not
working. It is harder for a neighbor to identify that a
post-construction BMP is not being installed accord-
ing to specifications, although this can become very
apparent offer construction is complete if the neigh-
bor experiences increased flooding (for example).
Nevertheless, the public can be great source of general
information about Stormwater issues in the neighbor-
hood—areas that flood, how runoff patterns change
during construction, and the like—and their input can
be helpful to generate "red flags" about the Stormwa-
ter design of a project.
The more the public is educated about Stormwater
BMPs, the more helpful they can be. Therefore, it is
important to provide training, workshops, fact sheets,
and other outreach materials. In addition, providing
information online about specific projects will allow
public access to development information.
Obvious public stakeholders include developers and
contractors. It is important to listen to their concerns
and input regarding BMPs that work well and those
that are difficult to install or maintain. Table 8.5 lists
key stakeholders in the post-construction BMP inspec-
tion process, along with several strategies that can be
employed for public involvement. The table lists the
following categories of stakeholders:
Primary stakeholders are those who are involved
directly in the BMP construction and installation
process, including contractors and, in some cases,
the applicant's design consultant.
• Inspection coordination stakeholders are other
departments or agencies that play a role in
inspecting the site during construction or in
verifying that various site plan elements or permit
conditions are implemented. Coordination with
these stakeholders is important to avoid giving
conflicting messages to the contractor.
Other stakeholders are parties that might have an
interest in a particular site or construction issues in
general (e.g., adjacent property owners, builders,
watershed groups).
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Table 8.5. Key Stakeholders in Post-Construction BMP Inspection and Selected Strategies
Stakeholder Group
Selected Public Involvement Strategies
Primary Stakeholders
>• Applicant
>• Applicant's design consultant
>• Contractor(s)
>• Electronic or Web-based plan tracking
>• Training and workshops on BMP construction for
contractors and citizens, especially information that may be
new to the local community (e.g., LID, Stormwater credits)
Inspection Coordination Stakeholders
>• Erosion control inspector/administrator
>• Forest conservation inspector
Dam safety inspectors
>• Building inspectors
>• Army Corps of Engineers/local wetland and waterways
inspectors
Joint pre-construction meetings
>• Joint site visits
Joint enforcement mechanisms
Cross-training with relevant departments
Other Stakeholders
>• Local environmental groups
Local builders'association
Property owners and residents in vicinity of project
>• General public
Adjacent property owners
Training for citizens about proper construction methods
Web-based system on construction inspection and
compliance
Requirement for public access to records
Fact sheets for adjacent owners
Hotline for receiving complaints
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Chapter 8: Inspection of Permanent Stormwater BMPs During Construction
Managing Stormwater in Your Community
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Chapt<
Developing a Maintenance
Program
Chapter 1
Introduction &
Background
Chapter 10
Tracking, Monitoring
& Evaluation
Chapter 2
Program
Development
Chapters
Linking Stormwater to
Land Use
Chapter 9
Maintenance
Program
Chapter 4
Stormwater Approach
& Criteria
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 5
Post-Construction
Ordinance
Chapter 7
Plan Review
Process
Chapter 6
Stormwater Guidance
Manual
Stormwater
Manual Builder
Plan Review, BMP
Construction & Maintenan
Checklist
Performance
Bond
Companion Tools for Chapter 9
Download Post-Construction Tools at:
www.cwp.org/postconstruction
Managing Stormwater in Your Community
What's In This Chapter
Framework for Stormwater maintenance programs
i Current status and trends in Stormwater
maintenance
Scoping out the maintenance program
i Three maintenance approaches
Private maintenance
Local program maintenance
Hybrid approach
Tips for developing an effective maintenance
program - from the drafting board to the field
Public involvement in the maintenance program
-------
Chapter 9: Developing a Maintenance Program
9.1. Introduction
Framework for Stormwater Maintenance
Programs
A great deal of effort is involved at the front end of
developing a stormwater program. Getting storm-
water best management practices (BMPs) included on
design plans and constructed properly in the field is
a major accomplishment, but it is only the beginning
of the actual life of the BMPs. Ongoing maintenance
is needed to ensure that the BMPs will continue to
perform as designed. In fact, lack of adequate main-
tenance is the primary shortcoming for most local
stormwater programs across the country.
Local stormwater managers are increasingly aware
that infrastructure for stormwater BMPs requires
maintenance. And, as with any infrastructure, deferred
maintenance can increase costs and negatively affect
receiving waters; unmaintained BMPs will ultimately
fail to perform their design functions and might
become a nuisance or pose safety problems. Local
governments inherit problems arising from deferred
maintenance. Therefore, developing and implement-
ing an effective maintenance program is essential.
This chapter reviews existing stormwater maintenance
programs and common challenges associated with
implementing such programs. Three approaches to
maintenance are discussed in detail: (1) private prop-
erty owner maintenance, (2) local government main-
tenance, and (3) shared maintenance between public
and private entities.
This chapter also discusses BMP design and construc-
tion considerations that affect maintenance and offers
tips for conducting inspections. In addition, it presents
strategies for public involvement in maintaining BMPs.
9.2. Current Status and Trends in Stormwater
Maintenance
Only a small percentage of local programs have
developed basic operational maintenance programs.
Common pitfalls of stormwater maintenance programs
include the following (CWP, 2006):
• Lack of funding
Uncertainty of the physical location of BMPs
Inability to track responsible parties
• Lack of dedicated inspection staff
• Designs that are not conducive to easy maintenance
• Lack of compliance and enforcement authority
• Owners unaware of their maintenance
responsibilities
Historically, maintenance activities are difficult to
implement for the reasons outlined in Table 9.1.
9.3. Getting Started—Scoping Out the
Maintenance Program
The following questions are designed to assist storm-
water managers in scoping out their maintenance
program responsibilities. Table 9.2 is a maintenance
program service matrix that may help a local program
manager scope out the types and level of service for
the program.
1. How large is the maintenance task?
Local programs cannot develop a maintenance pro-
gram until an inventory of existing and anticipated
future BMPs is conducted. Programs must also deter-
mine what elements of the drainage infrastructure
should be included in the maintenance program. For
example, will the maintenance program be limited to
the actual BMPs, or will it also include conveyance sys-
tems (pipes and ditches), discharge points, floodplains,
and/or stream channels?
An important part of the inventory is assessing the
physical and regulatory condition of the system. The
physical condition includes the stability and function-
ality of BMPs and conveyances. The regulatory condi-
tion addresses whether BMPs and conveyances are
located within easements, have proper maintenance
access, and are covered by maintenance agreements
or covenants.
2. Who is responsible for maintenance?
Assigning maintenance responsibility is one of the
most important policy decisions, and the ques-
tion may have multiple answers. For instance, the
Managing Stormwater in Your Community
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Chapter 9: Developing a Maintenance Program
Table 9.1. Common Maintenance Pitfalls
Insufficient funding
At the root of many maintenance problems is the lack of a stable, long-term funding source.
Depending on the level of service a community provides, performing BMP inspection and
maintenance can be expensive. It is a real challenge for many communities to know what resources are
needed to fund maintenance and repairs and to develop a system that provides consistent funding
over the long term.
Uncertainty of the
physical location of
BMPs
In many communities, the location of stormwater BMPs and conveyance infrastructure has not been
tracked as they are constructed. Typically, many communities are not aware of the total number of
practices within their boundaries, or whether the BMPs approved have actually been constructed.
Inability to track
responsible parties
Even if a community (or local government) is able to track the location of a BMP, the land ownership
often changes hands, and the community might not know who the current owner is at a given time.
Another common problem is that a homeowners association (HOA) can change leadership or dissolve
overtime, leaving no real mechanism to maintain existing BMPs.
Lack of dedicated
inspection staff
Inspecting and maintaining stormwater BMPs is potentially a full-time job, but few communities have
a full-time inspector on staff. As a result, repairs are often ordered in response to citizen complaints,
rather than as a part of a comprehensive maintenance plan. Thus, many of the practices that a re "out
of sight" (e.g., underground practices) go without needed maintenance, resulting in a significant loss
of pollutant-removal capability.
BMP designs that
are not conducive to
easy maintenance
Many BMPs have been constructed without design features that reduce the maintenance burden over
time. Examples include inadequate maintenance access, insufficient pretreatment, inlets and outlets
prone to clogging, and designs that require confined space entry for maintenance. Lack of adequate
design for maintenance increases the frequency of needed maintenance activities, and it hampers the
ease with which maintenance and inspections can be conducted.
Lack of compliance
and enforcement
authority/access
Although many communities have maintenance requirements incorporated into a stormwater
ordinance, many also lack the real teeth to ensure that maintenance actually happens. Important
compliance issues include escalating enforcement procedures (as problems become increasingly
severe), maintenance access, and legal authority to inspect and to compel maintenance.
BMP owners unaware
of maintenance
responsibility
As a property changes hands, maintenance agreements and other documents outlining maintenance
needs are easily lost or buried within property deeds. This leaves practice owners unaware of long-
term BMP maintenance responsibilities and costs.
local government or an associated utility may be
responsible for BMPs on public land and within public
rights-of-way, but maintenance for BMPs on private
land may be a shared responsibility. This decision may
depend on the status of easements, maintenance
agreements, and whether maintenance tasks are aes-
thetic or structural.
3. What is the current status of legal tools for
maintenance?
Local programs must have the legal authority to require
maintenance of BMPs, or it is likely that maintenance
duties will be neglected. The proper legal authority
includes: assigning maintenance responsibility through
legally binding agreements, adequate access to BMPs,
and enforcement mechanisms. See Chapter 5 and
Tool 3: Model Ordinance for more guidance on devel-
oping a post-construction ordinance.
4. What "level of service" is desired for the
maintenance program?
The level of service defines the frequency and scope
of maintenance. For example, will BMP inspections
take place on an annual or semiannual basis? Will
this vary based on the size and type of BMP, whether
the facility is public or private, and other factors such
as the threat of flooding if maintenance does not
occur? Will maintenance be performed in response
to complaints or emergencies, or will it be based on
inspection reports or on a preset schedule? Table 9.2
outlines several key level of service decisions.
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Chapter 9: Developing a Maintenance Program
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Chapter 9: Developing a Maintenance Program
5. Who is responsible for structural versus routine
maintenance?
This question is related to the level of service. There
are two types of maintenance: structural and routine.
Structural maintenance consists of repairing plumb-
ing, parts, and infrastructure, and it is typically costly.
Routine maintenance involves removing accumulated
trash and debris and managing vegetative growth (see
Table 9.3).
Table 9.3. Examples of Structural and Routine
Maintenance
Structural
Maintenance Items
>• Clogged or broken
pipes
>• Missing or broken
parts (e.g., valves,
seals, manholes)
Cracked concrete
>• Erosion at outfall or on
banks
>• Regrading or dredging
>• Landscaping
needs complete
refurbishment
Routine
Maintenance Items
>• Mowing
Removal of small
amounts of sediment
Removal of vegetative
overgrowth and woody
plants
Removal or trash and yard
debris
>• Replacing dead or
diseased landscaping
Control of invasive plants
Many programs assign responsibility for routine
maintenance to the landowner or responsible party
(e.g., homeowners' association, or HOA) while retain-
ing responsibility for structural items. As programs
become more sophisticated, routine repairs by the
local program are favored because performing routine
maintenance prevents serious and more costly repairs
in the future.
6. Should the local program use in-house resources, a
contractor, or both to perform maintenance tasks?
Local program managers who operate large, public
facilities may use in-house staff to conduct BMP
maintenance in conjunction with operating and
managing utilities, buildings, and roads. For many
smaller programs, however, employing private
contractors is more efficient than hiring new staff and
purchasing equipment. Another option is entering
into an agreement with a water and sewer utility,
neighboring jurisdiction, or transportation agency
to share maintenance responsibilities and maximize
economies of scale in the use of equipment and
personnel.
7. How will maintenance compliance be tracked,
verified, and enforced?
Local stormwater ordinances (see Chapter 5) and
program tracking and evaluation systems (see Chapter
10) are key components of a strong program. Before a
stormwater plan is approved, each plan should have a
recorded maintenance agreement that can be used to
help track maintenance. Checklists can then be used
to determine whether performance criteria have been
met (see Tool 6: Checklists). Finally, when maintenance
is not performed, mechanisms to enforce compliance
must be in place.
9.4. Three Maintenance Approaches
There are three general approaches that communities
can use to implement a stormwater maintenance
program:
1. Private property owners are responsible for
performing stormwater BMP maintenance. (The
local program provides oversight and guidance.)
2. The local program is responsible for performing
maintenance.
3. A hybrid consisting of both public and private
entities responsible for various maintenance tasks.
Table 9.4 outlines the characteristics of each approach,
as well as typical program budgets and funding
mechanisms. Most stormwater programs include
features from all three approaches.
Approach 1: Private Maintenance
Using this approach, private landowners or HOAs are
primarily responsible for routine maintenance and
major structural repairs. Public maintenance, where it
does occur, is limited to facilities on public property.
Placing maintenance responsibility in the hands
of individual property owners, HOAs and business
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Chapter 9: Developing a Maintenance Program
Table 9.4. Three Maintenance Program Approaches
Typical Program Characteristics
Typical Annual
Maintenance
Program
Budget Range3
Typical Funding
Mechanisms
1. Private Maintenance
Property owners and homeowners associations responsible for
maintenance
Less costly for local program, but often is a neglected program element
Legal and program tools needed to establish responsibility: ordinance,
maintenance agreement, easements, and compliance tools
Strong outreach and education needed for effective program
$5Kto$100K
General fund
Plan review and inspection
fees
Maintenance bonds or
escrow accounts
2. Local Program Maintenance
>• Local program responsible for most maintenance functions
Owners may be responsible for routine tasks (mowing, picking up trash,
aesthetics)
Requires highest budget and staff commitment
More common in cities and towns with established public works function
and jurisdiction over roads and drainage
$100Kto$1.5M
Stormwater utility
Other utility (e.g., sewer)
rates
Transportation maintenance
funds
General fund
3. Hybrid Approach: Blend of Public and Private Maintenance
>• Local government maintains facilities on public land and/or major
private facilities within easements, while private parties are responsible
for facilities on most private property
>• Most common maintenance approach
>• Can be cost-effective, but still requires local government budget and
staffing
$50Kto$300K
Stormwater utility
Capital improvement
program
General fund
a Maintenance program budget figures were derived from research on local Stormwater programs, primarily Phase II MS4s,
conducted in 2005 (CWP, 2006). Because most programs are still in the early stages of program development, these figures
represent nominal costs associated with a maintenance program, and do not include other costs, such as the cost of Stormwater
capital improvement projects. Costs will increase as program responsibilities and accountability increase. Typically, larger
municipalities, such as Phase I communities, have much larger maintenance budgets.
owners significantly reduces the costs to the
municipality and may be the best option for small
communities that cannot afford to allocate staff
and crews to maintain BMPs. The local program still
plays a significant role under this option, however,
by educating property owners and HOAs, tracking
maintenance, and initiating enforcement when
needed. If the program fails to fulfill these roles, an
inadequate level of maintenance is inevitable.
The following six steps outline a general process for
establishing a private maintenance program:
Step 1: Develop Program Documents
The program's legal and administrative foundation
must be established in the Stormwater ordinance
(Chapter 5), design or policy manual (Chapter 6), and
other forms and applications.
A preliminary list of necessary documents is provided
in Table 9.5.
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Chapter 9: Developing a Maintenance Program
Table 9.5. Legal and Administrative Foundation for a Maintenance Program
Stormwater Ordinance
Requirement for responsible party to maintain
BMPs
General design standard to include
maintenance reduction features
Requirement for a maintenance agreement or
covenant recorded with property deed
Requirement for easements
Maintenance inspection frequency and
reporting
Requirement for performance bond to cover
initial installation and period of operation
(e.g., 2 years)
Compliance and enforcement tools
Design/Policy Manual
Detailed maintenance reduction design
specifications (see Chapter 6)
Standard (template) maintenance agreement
Standard easement deed and specifications
(when required, width, rights of grantor and
grantee)
Maintenance checklists and sample operation
and maintenance (O&M) plans
Performance bond forms (see Tool 7:
Performance Bonds)
Notice of Violation letter template
Schedule of civil and/or criminal penalties
Other Forms and
Application
Maintenance handbookor
guide for responsible parties
Civil penalty "ticket book" for
inspectors
Step 2: Verify maintenance provisions during
stormwater plan review
As noted in Chapter 7, the plan review process should
ensure that all necessary documents are in place when
a project is approved. These include:
Maintenance agreements, including the identity
of a responsible party and the applicable parcel(s),
which are recorded in the property deed (examples
of maintenance agreements can be accessed with
Tool 5: Manual Builder)
Operation and maintenance (O&M) plans, which
are part of the approved plan and/or maintenance
agreement
Easements, which are accurate and shown on the
final property plat
Performance bonds, if applicable (see Tool 7:
Performance Bonds)
Step 3: Develop Outreach Materials and Programs
for Design Consultants and Responsible Parties
Educating homeowners, HOAs, and businesses about
BMP maintenance is critical. Often, property owners
are unaware of what a BMP is, how it functions, and
what is required for maintenance. When development
is proposed for a new site, the following educational
outreach efforts should be conducted:
• During Plan Development: A municipal staff person
should work with the developer, contractor, or
design consultant to develop a maintenance plan
for each BMP. At the pre-construction meeting,
the parties should review the maintenance plan,
maintenance responsibilities, and schedules.
During Ongoing Maintenance: A municipality
typically provides technical assistance to HOAs and
businesses after the plan is developed. Technical
assistance may include providing lists of local
contractors who conduct maintenance or repairs,
developing a budget for maintenance, providing
maintenance handbooks written for citizens, and
accompanying owners or contractors during routine
and post-repair inspections. Some programs, such
as "Adopt-A-Pond," develop citizen-friendly guides,
training opportunities, and recognition and awards
for participants.
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Chapter 9: Developing a Maintenance Program
Step 4: Develop Inspection Procedures
There are three basic approaches for maintenance
inspections:
1. Local program staff conducts inspections: This
option requires the most time, staff, and funding,
but it provides local programs with the best control
over inspections.
2. Local program hires contractors to conduct
inspections: This approach reduces staff time, but it
requires contract management and quality control
to ensure that thorough inspections are conducted.
Local program staff members are responsible for
compliance and enforcement.
3. Private parties responsible for inspections:
Responsible parties can conduct inspections with
in-house personnel (or HOA volunteers) or by hiring
a contractor. This approach still requires the local
program staff to conduct spot inspections and to
ensure overall compliance. Under this scenario, the
local program could sponsor an inspector training
and certification program to promote consistency
and quality control.
Step 5: Establish a Tracking System
Regardless of whether the municipality or the property
owner is performing the BMP maintenance, tracking
maintenance activities is important. Automated sys-
tems could be established to send notices to property
owners when inspections and routine maintenance
should be performed, or when an inspection by a
municipal staff person reveals specific maintenance
needs (see Figure 9.1).
After changes in property ownership, updating
responsible party information is an important, but
often difficult, tracking function. Often, no formal
mechanisms are in place for notifying local programs
when a property with a deeded maintenance agree-
ment is sold. The local program must work with the
real estate office or send frequent (annual) notices to
responsible parties requesting updated information.
Figure 9.1. Many BMP tracking systems use GIS and related databases to track location, ownership, condition,
and other BMP characteristics (Source: CWP, 2006; Graphic: Albemarle County, VA)
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Chapter 9: Developing a Maintenance Program
Step 6: Administer Compliance and Enforcement
Procedures
The municipality is responsible for enforcement
actions when maintenance activities are not con-
ducted. Language in ordinances must specifically
define maintenance enforcement procedures and
timelines. Typically, municipalities are responsible for
educating property owners about these procedures.
A tiered enforcement procedure is often best.
Initially, responsible parties can be notified, verbally
or in writing, of inspection and maintenance tasks. If
needed repairs are not performed accordingly, a more
formal notice of violation that outlines specific tasks
and a schedule can be issued. In cases of continued
noncompliance or negligence, or where lack of
maintenance poses a threat to public health and safety
(e.g., potential dam breach), penalties and fines may be
assessed and issued.
Table 9.6 summarizes several compliance and enforce-
ment methods that can be used for BMP maintenance.
Table 9.6. Review of Available Compliance Methods
Method
Maintenance
agreement
Performance
bond
Notice of
Violation
(NOV)
Civil penalty
Criminal
penalty
Maintenance
escrow
requirement
Stage of Compliance
Recorded at project
review. Used during life
of BMP as basis for other
enforcement measures.
Posted at project review.
Usually used during
construction and initial
installation of BMPs.Can
be extended to cover
initial period of post-
construction maintenance
(e.g., 2 years)
First stage of enforcement
after inspection and
documentation of
noncompliance
Escalating level of
enforcement if NOV does
not lead to compliance and
bond has been released
Alternative to civil
penalties when remedies
listed above are not
adequate
Not common, but could
be effective tool at
completion of construction
Description
This agreement is a contract between a local government and a property
owner designed to guarantee that specific maintenance functions are
performed. A maintenance agreement usually specifies that, in cases of
noncompliance, the local program can enter the property to make necessary
repairs and assign applicable costs to the owner. Examples of maintenance
agreements can be accessed with Tool 5: Manual Builder.
In a typical stormwater management performance bond, a site developer
or property owner guarantees that construction of stormwater BMPs will
be completed in accordance with the terms of a stormwater ordinance and
approved stormwater design plan. Should the site developer or property
owner fail to meet the performance measures, the bond ensures that
enforcement action can betaken by the jurisdiction at the developer's or
property owner's expense (see Tool 7: Performance Bond).
As a first step in the compliance process, the owner or responsible party is
sent an NOV outlining the nature of the violation, the specific actions needed
to come into compliance, a schedule for completing the remedies, and
subsequent penalties that can be imposed if the actions are not taken.
As an incentive for compliance, a municipality can levy a monetary penalty
for noncompliance. This penalty can be a fixed amount, or the amount could
increase with the severity of the violation or the frequency of recurrence.
A criminal penalty can be levied for more serious cases in which a party can be
considered intentionally or knowingly negligent.
A property owner is required to post a cash escrow, letter of credit, or other
acceptable form of performance security in an amount that would cover costs
associated with maintenance and repair or replacement in the event of BMP
failure.
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Chapter 9: Developing a Maintenance Program
Approach 2: Local Program Maintenance
Using this approach, the local program is responsible
for BMP maintenance. This approach is not widespread
among MS4 communities, primarily because of the high
costs, extensive staffing, and administrative burden
placed on the program. This approach, however, has
advantages: Enforcement issues can be avoided, and
the local program has more control over when and how
maintenance takes place. In many cases, municipalities
can transition from private maintenance (Approach 1) to
local program maintenance (Approach 2) as the pro-
gram matures. This transition would require the local
program to inventory existing BMPs and conveyance
systems to determine immediate maintenance needs.
In general, this approach requires local programs to col-
lect and manage detailed information about each BMP,
maintain a team of dedicated staff, and secure funding.
A typical process for establishing this type of program
is outlined below.
Step 1: Inventory BMPs
Local programs must inventory BMPs, including
collecting information on the physical condition of
the structures and determining whether the BMPs are
within easements (or under fee-simple ownership)
and have adequate maintenance access. Table 9.7
lists typical items that should be included in a BMP
inventory.
Step 2: Establish Maintenance Policies and
Funding
This step requires critical policy-making decisions,
which serve as the foundation for program budget
and staffing and for determining level of service. A
typical decision may include determining responsi-
bility for structural versus routine maintenance (see
Table 9.3). In most communities, simple aesthetic
and routine tasks, such as mowing and trash removal,
are performed by the property owner or responsible
party. These activities require equipment and staffing,
and they are more challenging for municipalities to
undertake on a frequent or routine basis. See Table 9.2
for additional level of service policy decisions.
Table 9.7. BMP Inventory Checklist
Physical Condition
Programmatic Condition
Type of BMP
>• BMP Design Features: size of practice, drainage area, treatment area/
volume, design storm(s), pipe sizes, etc.
Structural stability of dams/impoundments, if applicable
Integrity of pipes and risers
Condition of emergency spillway or by-pass channel
>• Manholes and inlets in place and locked (if necessary)
>• Standing water or nuisance conditions
Sedimentation or sediment buildup
>• Evidence of clogging, ponding (infiltration, bioretention, filters)
Evidence of dumping (trash, yard debris)
Status of vegetation
>• Water enters and exits BMP per design
BMP is built according to design (e.g., dimensions, size, elevations)
>• Is BMP within easement? Are easement
dimensions adequate? Any utility
easements (that may interfere with BMP
function or maintenance)?
Any existing maintenance agreements in
force?
Maintenance access platted and exists in
good condition on ground?
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Chapter 9: Developing a Maintenance Program
Step 3: Secure Easements for New BMPs during
Plan Review
Securing easements after a project is built and after
properties are occupied is time-consuming and has
uncertain results. Therefore, program managers should
strive to secure easements during the review of storm-
water plans. This requires the stormwater reviewer to
coordinate with the department or staff person that
reviews property plats. To be of legal standing, the
easement must be shown on the plat of record.
Programs that promote low-impact development
(LID), dispersed, and distributed practices—possibly
on individual lots—may have to develop LID-specific
easement policies and procedures. There are legal,
administrative, and logistical considerations for having
easements cover these types of practices, and for the
long-term access and maintenance of the practices.
The local program may want to consider a "hybrid"
approach (see below) for certain categories of BMPs.
Table 9.8 provides some considerations for securing
stormwater easements.
Step 4: Secure Easements and Agreements for
Existing BMPs
Depending on the level of service, securing agree-
ments to access and maintain BMPs in the existing
inventory may be necessary. Many existing BMPs
require costly repairs to achieve a good operating
status. It is not uncommon for the local program to
assume responsibility for the BMPs only after the
private party (1) conducts maintenance of the BMP to
a minimum performance level and (2) provides legal
access and easement documents.
This element of the program can be very time-
consuming. It requires documenting the condition
of BMPs, negotiating with multiple property owners,
and involving legal staff and often elected officials. For
these reasons, securing easements and agreements
for existing BMPs will likely be a phased program.
A scoring or ranking system can help a program set
priorities for this task.
Table 9.8. Considerations for Stormwater Easements
Easements should cover:
BMPs
>• Enough land around BMPs for construction equipment to enter and maneuver. This includes access to dams, risers, safety
benches, forebays, and outlets, as appropriate.
>• For ponds, a setback (e.g., 25 feet) from the flood (100-year) pool area
Access routes for maintenance
According to program policies, conveyances and structures associated with BMPs
For drainage easements, the easement width should increase as the top width of the channel or depth of the pipe increases. For
instance, increase the easement width in increments of 5 feet for pipes that are 10,15,20 feet deep, etc.
Ensure that access routes are of adequate width (minimum of 12 feet) and acceptable longitudinal slope (15% or less). Surfacing
should be based on anticipated frequency of use and types of equipment. Although gravel may be a suitable surface, consider
pervious surfaces, such as reinforced turf or paver blocks, that do not increase the site's impervious cover.
Make sure easements are recorded on the property plat and in the deed.
Easement agreements or deeds of easement will help specify the rights and responsibilities of both the easement holder and the
owner. For instance, the deed or agreement can spell out that the owner is responsible for mowing and routine maintenance, and
that fences and other obstructions are not permitted.
For examples of easement specifications and documents, see Tool 5: Manual Builder.
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Chapter 9: Developing a Maintenance Program
Step 5: Train Inspectors
Inspector training and certification are essential for
a program that conducts most of its maintenance
operations. Inspectors need to be well versed in the
use checklists (see Tool 6: Checklists) and provide
feedback on maintenance activities to program
managers (Figure 9.2).
Step 6: Develop a Tracking System
Tracking BMP maintenance is essential for both local
programs and private property owners. In large com-
munities, tracking systems are technically advanced and
use linked systems comprising geographic information
systems (CIS), global positioning systems (GPS), and
hand-held data collectors. However, simpler CIS and
hard-copy file formats can also be used. Table 9.9 lists
items that are appropriate for local programs to track.
Another critical task is collecting data about specific
maintenance activities and their costs. Tracking
systems can monitor costs for performing inspection
and maintenance services. These data can assist local
programs in estimating future expenses and developing
more cost-effective means to accomplish tasks.
Step 7: Perform and Document Maintenance
Activities
It is common for all but the largest communities to rely,
at least partially, on outside contractors to conduct
maintenance and repair activities because of the over-
head equipment costs and specialized skills needed to
conduct the full range of maintenance activities (Figure
9.3). One alternative is to form a separate organization
or special "district," such as a stormwater utility, that
is responsible for all maintenance and inspections.
Another option is to include stormwater maintenance
responsibilities in an existing utility, such as a water and
sewer authority. Such a utility or district would have a
dedicated funding source to ensure longevity.
Approach 3: Hybrid of Public and Private
Maintenance
A blend of public and private maintenance, the most
common approach for local programs, provides
maximum flexibility for assigning maintenance respon-
sibilities. Programs using this approach are typically
shifting some maintenance activities from HOAs and
other private parties to local programs because the
private entities have proved incapable of performing
all maintenance activities. Often, a particular problem
or high-profile complaint to elected officials causes the
shift to occur.
The process for building a hybrid program contains
elements of approaches 1 and 2, and program
managers should refer to the steps in this chapter for
those approaches. A supplemental step is relevant to
hybrid programs.
Figure 9.2. Inspector training helps inspectors understand the function and maintenance needs of BMPs
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Chapter 9: Developing a Maintenance Program
Table 9.9. Tracking Items for a Municipally Operated Maintenance Program
Inspection dates and reports
>• BMP locations
General condition of BMPs (see Tool 6:
Checklists)
*• BMP features: size of practice, drainage area,
treatment volume/design storm, age, pipe sizes,
etc.
*• Photos
>• Information needed to prioritize maintenance
tasks. For instance, the inspection process can
categorize BMP maintenance needs as (1) no
action, (2) routine maintenance needed,
(3) major maintenance needed, or
(4) remediation/reconstruction needed. This
type of BMP triage system is necessary to
allocate available resources.
Maintenance work orders
Maintenance schedules and/or documentation
on tasks completed
Costs for various maintenance tasks
Available BMP feedback or evaluation data
that can help program managers amend the
list of approved BMPs or particular BMP design
features
Good retrofit opportunities
Figure 9.3. Use municipal staff, contractors, or both to perform maintenance tasks
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Chapter 9: Developing a Maintenance Program
Supplemental Step: Be Clear about Various
Maintenance Responsibilities
Maintenance responsibilities must be clearly outlined
for program success. One danger of a hybrid system
is that maintenance responsibilities are not systemati-
cally assigned and communicated. Local program staff
must understand who is responsible for maintenance
tasks and must ensure that private parties understand
their role. Table 9.10 provides some recommendations
on how to clarify roles and responsibilities.
Table 9.10. Methods to Assign and Communicate
Maintenance Responsibilities
>• Make explicit policy decisions based on program goals
and the characteristics of the community. Don't assume
that all parties will know what they're supposed to do.
Use a deed of easement or easement agreement to
clearly outline rights and responsibilities. See also
Table 9.8, Considerations for Stormwater Easements.
Use a maintenance agreement that clearly outlines
responsibilities for routine versus structural maintenance.
Develop a guidebook or other outreach materials geared
toward HOAs and responsible parties.
>• Explain maintenance responsibilities during
co-inspections.
>• Include maintenance information on the program Web
site.
Table 9.2 lists components of maintaining the drainage
system, which could be assigned to the local program
or private parties for maintenance. Assuming that most
or all of the functions in Table 9.2 must be performed
by some party, the local program must delegate
responsibilities. Local program staff would also monitor
all private-party activities to ensure that appropriate
inspection and maintenance tasks are performed.
9.5. Tips for an Effective Maintenance
Program—From the Drafting Board to the
Field
Maintenance must be considered throughout the
entire stormwater program—from early program
policy decisions, to design standards, to the
development review process, and, most important,
to inspection of BMPs in the field. The following
section provides tips on how to tailor design and field
procedures to consider long-term maintenance needs.
Figure 9.4 shows some good and bad examples of
design features related to maintenance.
This section is divided into two subsections:
1. On the Drafting Board: Tips for developing
design standards and for acknowledging and
accommodating long-term maintenance needs
during the initial design process.
2. In the Field: Procedures for inspecting BMPs to
ensure proper maintenance.
On the Drafting Board—Design Standards and
the Design Process
Tip #1 Authorize BMPs That the Program Is
Prepared to Maintain
Selecting or approving the right stormwater BMP is
key to ensuring success. Historically, poor selection of
BMPs contributed to failures and chronic maintenance
problems. Adding nonstructural BMPs, such as con-
serving natural areas, restoring riparian areas, and dis-
connecting impervious surfaces, to the list of approved
BMPs can also help reduce maintenance costs.
Designing BMPs as multifunctional and aesthetically
pleasing facilities promotes maintenance because
the public uses and takes interest in these areas. For
instance, BMPs that are designed as components of
greenways, walking trails, recreation areas, parks,
streetscapes, and courtyards have a higher likelihood
of receiving maintenance.
Table 9.11 outlines some of the key maintenance con-
siderations for various BMPs. Specific design features
are addressed in Chapter 6.
Tip #2 Develop BMP-Specific Maintenance
Plans
Maintenance plans can be incorporated into
approved design plans and/or as a component
of maintenance agreements. Maintenance plans
should identify the responsible party, include a list
and schedule for both routine and structural main-
tenance, and outline any legal mechanisms in place
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Chapter 9: Developing a Maintenance Program
Poor Examples
Good Examples
Maintenance Access and Safety:
Steep side slopes make maintenance difficult and are a safety hazard.
Practice Selection:
Underground BMPs can beoutof sight, out of mind when
it comes to maintenance.
No Pretreatment:
Without pretreatment, sediment can enter the main treatment
cell and inlets can erode.
Maintenance Access and Safety:
Shallow sides slopes and wetland benches are a maintenance
and safety feature.
Practice Selection:
Nonstructural BMPs, such as riparian restoration, can be
low-maintenance options and community amenities.
Pretreatment:
Forebays and pretreatment cells help protect the main
pond and ease future maintenance.
Figure 9.4. Examples of Poor and Good Maintenance Features Related to the Design Process
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Chapter 9: Developing a Maintenance Program
Poor Examples
Good Examples
Not a Community Amenity:
Unsightly basins in residential areas tend to become
nuisances and generate complaints.
No Planting Plan:
Lack of plants and landscaping make BMPs
unattractive and undesirable to maintain.
Poor Conveyance:
Improperly designed conveyances become
maintenance problems in the future.
Community Amenity:
Stormwater BMPs, such as this rain garden, can be designed as
amenities, with plantings, interpretive signage, and public access.
Planting Plan:
Plants are being added to this regional basin to
enhance aesthetics and water quality functions.
Good Conveyance:
Good conveyance design can include check dams,
vegetation, and adequate channel lining.
Figure 9.4. Examples of Poor and Good Maintenance Features Related to the Design Process (continued)
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Chapter 9: Developing a Maintenance Program
that guide long-term maintenance (i.e., maintenance
agreements, easements, and/or deeds of easement).
Tool 6: Checklists can assist with typical maintenance
tasks for specific categories of BMPs.
Tip #3 Provide Runoff Pretreatment
Pretreatment refers to the techniques used to provide
storage or to filter out coarse materials before storm-
water enters the BMP. Proper pretreatment preserves
a greater fraction of the water treatment volume
over time and prevents large particles from clogging
orifices, filter material, and infiltration sites. The specific
techniques and volumes of stormwater treated vary by
the type of BMP used. Common pretreatment prac-
tices include forebays, vegetated filter strips, stone
filter strips (for higher velocities), and grass channels.
One important consideration for pretreatment is that
these practices usually require frequent maintenance,
such as sediment and trash removal.
Tip #4 Carefully Design Conveyance Systems
High flows into, through, and out of the BMP often
cause erosion and increase maintenance burdens. To
minimize erosion, designs should consider inlet and
outlet protection, conveyance channels, and seepage
prevention.
Conveyance channels can be an important part of the
treatment train and require special design consider-
ations to minimize maintenance. They can also be a
maintenance burden, particularly if sediment accumu-
lates within the channel or if flows cause erosion within
the channel.
Tip #5 Ensure Long-Term Maintenance Access
Site access must be safe and must provide enough
room for construction vehicles to perform mainte-
nance. Access should include a dedicated easement
that guarantees right of entry. These requirements are
adequate for filtration and open-channel devices, but
the access requirements for aboveground or open-air
BMPs, and for surface treatments, are slightly different.
For example, for ponds and wetlands, it is important
that the access paths/roads have adequate width
(12-foot minimum is common) and appropriate longi-
tudinal slopes (maximum of 15% is recommended) to
allow maintenance vehicles to enter and turn around.
Programs can also consider surface treatments, such
as reinforced turf, that do not increase a site's impervi-
ous cover. Maintenance access should extend to the
forebay, safety bench, and outlet/riser area. Risers
should be located in embankments for access from
land, and they should include access to all elements via
a manhole and steps.
Tip #6 Include Safety Features
The best overall approach is to select BMPs that include
safety features. Many BMPs do not involve standing
water, steep dropoffs, or large risers and barrels, and
they should be considered as the best options.
When ponds or basins are used, however, the design
should incorporate safety features that prevent easy
access to confined spaces (e.g., risers and barrels), limit
drowning hazards associated with permanent pools of
water, and protect the BMP from vandalism.
Many communities use fences to prevent access to
ponds or basins. Alternative approaches include the
use of mild side slopes, wetland or safety benches, or
thick vegetation.
Riser structures can also be used, but methods to
reduce vandalism must be implemented. Riser man-
holes should be locked, and any openings in the riser
should be covered with an appropriate trash rack. In
addition, the operator valves for pond drains should
be chained and locked to prevent unauthorized use.
Tip #7 Plan for Sediment Removal and
Disposal
Removing sediment and debris is a common main-
tenance item for ponds, wetlands, and other types
of BMPs. Minor debris removal is relatively simple,
but removing large quantities of sediment can be a
major and costly undertaking. Design features should
enhance access, as described above, and include
features that minimize removal efforts. For example, a
pond drain is an important design feature that allows
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Chapter 9: Developing a Maintenance Program
Table 9.11. Key Maintenance Considerations for Various BMPs
Type of Practice
Overall
Maintenance
Burden*
Key Maintenance Considerations
Stormwater Ponds
Periodically remove and dispose of sediments
Control woody vegetation on dam
Repair slumping, animal burrows, and seepage associated with dam
Prevent clogging of orifices
Prevent unauthorized access to deep water areas, risers, pipes, and manholes
due to safety concerns
Manage vegetation and remove trash
Prevent standing water and mosquito habitat (mostly associated with dry
extended detention ponds)
Stormwater
Wetlands
See above for ponds
Manage invasives
Filtration Practices
Prevent clogging of filter surface through frequent cleaning and removal of top
layer
Replace filter media when clogged
Pump out sedimentation chamber (e.g., sand filters)
Use confined-space entry procedures for some designs
Infiltration
Practices
I-L
Repair and restore clogged practices
Prevent standing water
Bioretention
>• Prune, replace, and enhance vegetation
Replace mulch layer frequently
>• Keep inflow points (e.g., curb cuts) flowing and free of sediment and debris
Replace filter surface or install wick drains if clogged
Keep underdrain clear
Control impacts from road salt and snow plows in cold climates
Open Channels
Remove sediment periodically
Manage vegetation
Repair erosion after heavy storms
Clear debris from upstream face of check dams, if applicable
Minimize standing water and mosquito habitat
Proprietary Devices
Conduct frequent to periodic pump-outs and disposal; requires approved
disposal method for liquids and solids
Clean or replace cartridges, filter media, etc., depending on device
Repair clogged orifices and by-passes
Use confined-space entry procedures for some designs
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Chapter 9: Developing a Maintenance Program
Table 9.11. Key Maintenance Considerations for Various BMPs (continued)
Type of Practice
Natural Area
Conservation and
Restoration
Sheetflow to Buffer
or Open Space (e.g..
Preserving Open
Space Designed to
Intercept and Treat
Runoff)
Impervious Area
Disconnection
Grass Channels
Overall
Maintenance
Burden*
L
L
M
M-L
Key Maintenance Considerations
>• Prevent encroachments, such as dumping yard waste, cutting of trees, clearing,
and minor encroachments (sheds, decks, etc.)
>• Manage invasives
>• Maintain runoff as sheet flow; repair erosion rills and gullies
>• Maintain energy dissipators, level spreaders, and other devices to maintain sheet
flow
>• Prevent adjacent uses from piping runoff through open space or buffer
>• Ensure runoff enters pervious area
>• Remove sediment and debris build-up at points where runoff enters pervious
area
>• Prevent adjacent uses from piping through or around pervious area
>• Manage vegetation in pervious area
>• Maintain any "structural" elements in design: level spreaders, energy dissipators,
rain gardens, etc.
Remove sediment periodically
>• Repair erosion after heavy storms
>• Manage vegetation
>• Minimize standing water and mosquito habitat
* L = low; M = medium; H = high
maintenance crews to drain ponds or wetlands before
removing accumulated sediment.
At sites where sediment loads are expected to be
high, designers should designate a dewatering and
storage area on the site. If on-site storage is not
practicable, sediment can be used elsewhere after
dewatering, unless the material was generated from
a stormwater hot spot (e.g., gas station). In this case,
a Toxicity Characteristic Leachate Procedure (TCLP)
or other analytical analysis should be performed on
the removed sediment to determine if it meets the
criteria of a hazardous waste and thus requires special
handling and disposal.
Underground or proprietary BMPs—such as vaults,
chambers, and other structures that require accumu-
lated material to be pumped out—require special
consideration because inspection and maintenance
staff could be required to have confined-space training
to satisfy OSHA safety requirements. Also, some types
of proprietary devices require frequent maintenance
to perform as designed, so maintenance contracts are
essential when such BMPs are specified on plans.
Finally, disposal operations must be carefully planned.
Some pump-outs result in a waste material that is
composed of both liquids and solids. Wastewater
plants do not customarily accept wastewater with
solids, and sanitary landfills do not usually accept any
liquids or saturated sediments. Therefore, maintenance
plans must generate a waste material that meets the
various disposal requirements.
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Chapter 9: Developing a Maintenance Program
Tip #8 Include Planting Plan
All BMP designs should incorporate plantings to
improve both function and aesthetics. If designed
correctly, planting plans can reduce future mainte-
nance liabilities. Landscaping can help prevent access
to ponds by geese and children, stabilize banks, and
prevent upland erosion. Ponds may rely on adjacent
trees and shrubs, or on planted tree mounds within
wetlands, for shading to reduce ambient water
temperatures.
Planting plans designed for bioretention should iden-
tify and recommend species that can tolerate wet and
dry conditions. All BMP designs should incorporate
landscaping to improve function and aesthetics. All
planting plans should specify a care and replacement
warranty.
In the Field—Maintenance Consideration
During Inspection and Maintenance Activities
Tip #9 Require As-Built Plans
After construction is completed, qualified engineers
and surveyors should prepare as-built drawings of
BMPs for a permanent record of the structures. The as-
built plans are a critical element of future inspections.
See Chapter 8 for more details on the as-built process.
Tip #10 Use Benchmarks and Markers
Benchmarks must be established for tracking and
monitoring BMPs. For example, in ponds and wetlands,
sediment markers (graded measuring sticks) placed
in forebays or permanent pools can be used to
consistently measure the depth of sediment during
inspections. Similar markers can be used to ensure that
the elevation of the permanent pool remains relatively
constant over time. Sediment clean-out markers
should also be used in underground vaults and in the
sediment chambers of sand filters.
Tip #11 Inspect LID Measures, Source
Controls, and Nonstructural BMPs in
Addition to Structural Practices
Program managers may incorrectly assume that non-
structural BMPs, such as vegetated measures, do not
require routine inspection and maintenance. However,
proper maintenance is essential for continued per-
formance. Like structural BMPs, restored natural and
riparian areas, disconnected impervious surfaces, grass
channels, and similar practices can fail if inspections
and monitoring are not routinely conducted.
For instance, sediment buildup and debris at entry
points may prevent sheet flow from reaching pervious
areas or buffers. Vegetation used to restore natural
areas may not have adequate survival rates. Land-
owner practices and behaviors, such as dumping yard
waste and rerouting roof drains, may compromise
the function of the nonstructural BMP. For all these rea-
sons, inspection and maintenance procedures should
be applied to LID and nonstructural measures.
Tip #12 Use Inspection Checklists
A community should use standard inspection
checklists to record the condition of all stormwater
BMPs. It is easier for communities to track maintenance
activities electronically, using either a database
or spreadsheet, rather than relying on paper files.
Well-designed checklists can be integrated within
maintenance databases to prioritize maintenance,
track performance over time, and relate design
characteristics to particular problems.
Tool 6: Checklists provides templates for maintenance
checklists based on the type of BMP, including LID and
nonstructural practices. Program managers can use
these templates to customize their own maintenance
checklists.
Tip #13 Take Photographs
Inspectors should take photographs of all BMPs. In
addition, specific problem areas should be photo-doc-
umented. For example, a recommended list of photo-
graphs for a BMP pond would include:
• Vehicle access points
• Overview of areas or related structures surrounding
the pond
Pretreatment areas
Wetland planting areas, if applicable
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Chapter 9: Developing a Maintenance Program
Inlets
Overview of principal spillway, upstream and
downstream faces of embankments, and
emergency spillway
Downstream outfall(s) from BMP
• Any problem areas identified
Tip #14 Document Repair Items
Inspectors should clearly document items that require
repairs. Notations on design plans and physical mark-
ers, such as spray painting the key areas of concern, can
help maintenance crews locate and correct problems.
In addition, the inspector should use a copy of the as-
built plan to mark potential corrections and problem
areas. The marked-up as-built plan should be stored
digitally or in a paper file system. Such record keeping
can be used on the follow-up inspection and will help
confirm that maintenance was performed correctly.
Neglected repairs, or missing or damaged structures,
may pose immediate safety concerns. Examples
include a missing manhole cover over a drop inlet,
a damaged grate at a large inflow or outfall pipe, or
damaged fencing around a pond with steep slopes,
which may allow unauthorized and unsafe access.
Furthermore, repairs related to dam safety and flood-
ing hazards must be implemented immediately. For
example, if a BMP shows signs of embankment failure,
or if an inspector is unsure, a qualified engineer should
investigate the situation immediately and appropriate
actions must be taken. Similarly, cracks in a concrete
riser that drains a large area may pose a safety threat
and should be repaired immediately.
9.6. Public Involvement in the Maintenance
Program
Educational outreach programs can improve compli-
ance with maintenance requirements. Local govern-
ments should provide residential or commercial
property managers with BMP inspection training and
workshops on how to perform basic maintenance.
Table 9.12 provides a list of typical stakeholders and
strategies for involving them in a maintenance pro-
gram. The following are some strategies:
Co-Inspections
Municipal staff can accompany property owners
and/or third-party contractors on inspections to help
identify maintenance needs. During these inspections,
the local program staff can educate the public, one on
one, about general stormwater concerns and specific
BMP functions. These inspections can also provide in-
field training to private inspectors, thereby promoting
thoroughness and consistency.
Education and Adopt-A-BMP Programs
Communities can establish a volunteer program for
BMP maintenance by recruiting motivated individu-
als, service groups, neighborhood associations, and
school groups. This approach works well for highly
visible BMPs that have safe and easy access. Typically,
volunteers perform simple inspections and light main-
tenance tasks such as trash pickup and weed removal.
The volunteers also report serious problems or more
labor-intensive maintenance needs to the local pro-
gram manager. Certificates of accomplishment, prizes,
publicity, or other incentives can be used to recruit
volunteers and provide a rewarding experience.
Several communities sponsor Adopt-A-Pond pro-
grams to provide citizens and responsible parties with
guidance and resources for maintaining and improv-
ing stormwater ponds. An example of such a program
from Hillsborough, Florida, can be found at:
http://www.hillsborough.wateratlas.usf.edu
The Adopt-A-Pond program could be broadened to
include other types of stormwater BMPs.
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Chapter 9: Developing a Maintenance Program
Table 9.12. Key Stakeholders in Stormwater Maintenance & Selected Strategies
Stakeholder Group
Selected Public Involvement Strategies
Primary Stakeholders
>• Private responsible party or HOA
>• Public agency inspectors
>• Public agency maintenance crews
>• Co-inspections with responsible party and public inspector
Brochures and mailings to responsible parties
>• Workshops, certifications, plaques, and other forms of recognition for
responsible parties
Adopt-A-BMP programs with training and certification
Workshops for inspectors with field component
>• Workshops, certification, and recognitions for maintenance crews
Other Stakeholders
Private sector contractors performing
inspections for responsible parties
Private sector contractors performing
maintenance tasks for responsible parties
Elected officials
>• Residents of neighborhoods with BMPs
Training and certification programs
Periodic updates for elected officials to tout benefits of maintenance
program (e.g., cost savings through proactive maintenance)
Hotline for maintenance questions and concerns from the public
General information brochures or Web sites on "what to expect from your
neighborhood BMP"
Fact sheet on BMPs, mosquitoes, and West Nile virus
Hotline or Web-Based System for Complaints
and Concerns
A telephone hotline, or a Web site with a reporting
form, is a good tool for increasing citizen involvement.
Using these methods, citizens can notify local program
staff about specific maintenance issues, request an
inspection, or ask technical questions. In response,
local programs must establish a procedure for address-
ing these reports or queries quickly. The hotline
or Web site should be advertised in utility inserts,
the government pages of the phone book, on the
municipal Web site, and through other communication
channels.
Workshops, Training, and Certification for
Inspectors
Training workshops can help standardize the inspec-
tion process by reviewing objectives, procedures, and
follow-up actions. In addition, peer-to-peer training
enhances communication because inspectors can
share challenges and problem-solving related to real
field experiences. Training tied to inspector certifica-
tion can also be a motivator to encourage others to
participate. A program can issue certificates and main-
tain lists of certified inspectors for future field work.
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Chapfc
Tracking, Monitoring, and
Evaluation
Chapter 8
Inspection of
Permanent BMPs
During Construction
Chapter 1
Introduction &
Background
Chapter 9
Maintenance
Program
Chapter 2
Program
Development
Chapter 7
Plan Review
Process
Chapter 3
Linking Stormwater to
Land Use
Chapter 4
Stormwater Approach
& Criteria
Chapter 5
Post-Construction
Ordinance
Chapter 6
Stormwater Guidance
Manual
BMP
Evaluation
Companion Tools for Chapter 10
Download Post-Construction Tools at:
www.cwp.org/postconstruction
What's In This Chapter
i Current status and trends in tracking, monitoring
and evaluation
A framework for post-construction tracking,
monitoring and evaluation
Establishing measurable goals
Selecting and tracking indicators of success
i Program indicator tracking
Stormwater infrastructure tracking
Land use/land cover tracking
Water resources monitoring and modeling tracking
Annual reporting and program inspections and
audits
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Chapter 10: Tracking, Monitoring, and Evaluation
10.1. Introduction and Overview
The ultimate goal of the Phase II MS4 program is to
implement practices that protect and improve water
quality. MS4 programs can assess their progress using
measures of success, such as achieving measurable
goals, assessing the extent and condition of storm-
water practices, evaluating the effectiveness of BMPs,
and demonstrating compliance with the MS4 permit.
Some of the chief purposes for program tracking,
monitoring, and evaluation include:
• Identifying and implementing program
improvements on an ongoing basis to better
protect water resources
Documenting program status for annual reports
required under the MS4 permit
Striving to make the program more cost-effective
Preparing for a possible regulatory inspection or
audit
• Documenting program value and accomplishments
to the public and elected officials
Ensuring the best progress toward meeting a
resource-based goal
This chapter provides an overview of techniques to
track progress, including program tracking goals and
indicators, water quality monitoring, and program
reporting.
10.2. Current Status and Trends in Tracking,
Monitoring, and Evaluation
Although many programs have a system to catalogue
BMPs, few make the effort to look at the bigger
picture of program accomplishments and milestones
through time. A relatively small number use program
evaluation tools, stream assessments, stream
monitoring, BMP monitoring, or load reduction
estimates to gauge success and track the progress of
the program (CWP, 2006).
10.3. A Framework for Post-Construction
Tracking, Monitoring, and Evaluation
Stormwater programs should continuously evolve
to reflect new information learned as the program is
implemented. A crucial part of this process is devel-
oping a system that consistently and quantitatively
measures the program's performance. Figure 10.1
illustrates a step-by-step process for tracking, monitor-
ing, and evaluation.
This iterative process ensures that even if the initial
goals established for a program prove to be unachiev-
able, the program can adjust and continue to move
forward. In addition, if some actions, projects, or
approaches do not achieve their stated aims or are
not cost-effective, adjustments can be made as the
program evolves. This process is necessary to achieve
improvements in water quality and aquatic habitats.
Finally, it supports the documentation of program
efforts, which can be helpful in both annual reporting
and regulatory inspection and audit procedures.
10.4. Establishing Measurable Goals
Measurable goals are design objectives or goals that
quantify the progress of program implementation
and the performance of BMPs. They are objective
markers or milestones that the local program, and the
permitting authority, will use to track the stormwater
program's effectiveness.
Measurable goals should include, where appropriate,
the following three components:
• The activity to be completed
• A schedule or date of completion
• A quantifiable target by which to measure progress
While this section provides a brief overview of tech-
niques to establish measurable goals (i.e., the activity
to be completed), the remainder of the chapter focuses
on specific tracking measures that help quantify
whether the target has been met.
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Chapter 10: Tracking, Monitoring, and Evaluation
Establish/
Refine
Measureable
Goals (10.4)
Select/Refine
Indicators (10.5)
Can
Goals Be
Measured?
baseline data)
Track Progress
(10.6-10.9)
Indicators
Adequate?
Actions,
Programs,
Goals Effectives
Achievable
Sufficient
Progress
Toward
Goals?
MS4 Audit/
Reporting
(10.10) May
Affect Elements
of the Process
Periodically Revisit
Figure 10.1. Post-construction tracking, monitoring, and evaluation framework
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Chapter 10: Tracking, Monitoring, and Evaluation
A program's success can be gauged by achieving a
combination of outcome-based and output-based goals
(See Table 10.1).
• Outcome-based goals focus on the ultimate desired
outcomes for the program, such as improving
stream health, improving water quality, or reducing
pollutant loads by a specific amount. These goals
are critical because they are the reason behind
developing a program. At the same time, it can be
difficult for an MS4 to commit to these outcome-
based goals for several reasons. These goals often
take a long time to achieve (longer than the typical
permit cycle), and they can be difficult to measure
or predict. In addition, achieving these goals often
depends on a combination of efforts and events,
some of which may be beyond the direct control of
the MS4.
MS4 programs should select a handful of outcome-
based goals that it considers challenging but
achievable and then track them over the course of
multiple permit cycles. Including these goals will
help focus and motivate the program to strive to
have a positive impact on receiving waters.
• Output-based goals focus on the activities that
achieve these outcomes, such as adopting an
ordinance, reviewing development plans for
stormwater, and inspecting all BMPs to ensure
that they are functioning properly. These goals
represent a checklist of items, and they are typically
controlled directly by the MS4. These output-based
goals ensure that the basic regulatory requirements
are met; they also support achieving the broader
outcome-based goals identified by the MS4.
Baseline data, such as current water quality condi-
tions, number of BMPs already implemented, or the
public's current knowledge or awareness of storm-
water management, inform the development of both
outcome—and output—based goals. During the
initial development of a stormwater program, some
data might be unavailable. The Stormwater Program
Self-Assessment (Tool 1) and Program and Budget
Planning (Tool 2) can help the MS4 assess its cur-
rent program resources and thus help define output-
based goals. Other data, such as past public polls or
existing stream monitoring data, if available, can also
help refine outcome-based goals.
Useful references for measurable goals include the
following:
Tool 1: Stormwater Program Self-Assessment
• Tool 2: Program and Budget Planning
USEPA, Measurable Goals Guidance for Phase
II and Small MS4s: www.epa.gov/npdes/pubs/
measurablegoals.pdf
• California Stormwater Quality Association (CASQA),
Municipal Stormwater Program Effectiveness
Assessment Guidance, 2007: www.casqa.org
10.5. Selecting and Tracking Indicators of Success
Indicators of success should be related directly to
and support the measurable goals established at the
program's onset. The selection of indicators will influ-
ence the record-keeping functions of the program.
Consequently, these indicators should be relatively
simple to measure and track over time.
A set of "base" indicators are needed to track many
aspects of the program. Base indicators are funda-
mental measures that most programs should adopt.
They can be supplemented by one or more additional
measures (supplemental indicators) that are tailored
to the specific needs, measurable goals, and degree
of sophistication of a specific program. Table 10.2 lists
some examples of base and supplemental indicators.
The table divides the indicators into the following
categories:
Program (Section 10.6.)
Program indicators track the progress of program
milestones, including permit compliance. Examples
include passage of an ordinance, adoption of
manuals, manual updates, or maintenance activities
conducted. These indicators track many of the
output-based goals that the program identifies.
Stormwater Infrastructure (Section 10.7.)
The tracking system for stormwater infrastructure
is a map-based system that documents the
location, construction, and condition of stormwater
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Chapter 10: Tracking, Monitoring, and Evaluation
Table 10.1. Examples of Measurable Goals for Post-Construction Practices: Keyed to Chapters of this Guide
NOTE: "XX" refers to a number to be identified by the specific MS4.
Chapter 2.
Program
Development
Chapter 3.
Land Use
Planning as the
First BMP
Chapter 4.
Stormwater
Management
Approach and
Criteria
Chapter 5.
Stormwater
Ordinance
Chapter6.
Stormwater
Guidance
Manuals
Chapter 7.
Plan Review
Process
Chapters.
Inspection
of Post-
Construction
BMPs During
Construction
Output-Based Goals
>• Develop maps with relevant environmental
information (such as watershed boundaries,
soils, land use).
>• Conduct a program self-assessment.
>• Secure a funding mechanism
>• Adopt a stream buffer ordinance.
>• Revise zoning and subdivision codes to
remove barriers to low-impact development
(LID) and conservation design.
>• Restrict development in sensitive watersheds.
>• Remove unnecessary barriers for infill
and redevelopment within targeted
redevelopment zones.
>• Develop a Stormwater program that includes
improving site design, source controls, and
structural BMPs.
>• Develop specific Stormwater management
criteria that address regulatory requirements
and local issues for inclusion in ordinances
and design guidance.
>• Adopt a post-construction Stormwater
ordinance.
>• Develop a Stormwater guidance manual or
provide local adaptations to a regional or
state manual.
>• Incorporate guidance on LID practices.
>• Develop a plan review and plan submittal
checklist.
>• Train staff and design consultants.
>• By the end of the permit cycle, XX% of new
plans are consistent with design criteria by
the second submittal.
>• Inspect all sites at least three times during
construction.
>• Develop checklists for staff inspectors.
>• Train contractors on key construction
requirements for Stormwater BMPs.
Outcome-Based Goals
>• Retain or increase XX miles of forested stream
buffer within sensitive watersheds.
>• Conserve XX acres of open space.
>• Reforest XX acres of land in critical
environmental areas.
>• Maintain XX% of forest cover in sensitive
watersheds.
>• XX% reduction in target pollutant (modeled
or measured) in watershed A.
XX% reduction in post-development runoff
volume for new development sites.
>• Progress toward meeting water quality
standards in watershed B by 2015.
>• XX% of new development sites that use LID
to better match pre-development hydrologic
conditions
>• XX% of developed land treated by
post-construction BMPs
*• XX pounds of the target pollutant (or
percent) removed based on approved
post-construction BMPs (modeled)
>• 100% of installed BMPs are built according to
standards and are operational before turning
over maintenance to responsible parties
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Table 10.1. Examples of Measurable Goals for Post-Construction Practices: Keyed to Chapters of this Guide (continued)
NOTE: "XX" refers to a number to be identified by the specific MS4.
Chapter 9.
Maintenance
>• Develop a formal maintenance inspection
schedule with priorities based on the type.
size, or "risk" of various BMPs.
>• Inspect each stormwater BMP at least
annually, or according to program schedule.
>• Inspect high-priority stormwater BMPs on
more frequent basis, according to program
schedule.
>• Inspect all preexisting (pre-ordinance) BMPs
by year 2 of permit cycle.
>• Address critical maintenance deficiencies
within 2 months of initial inspection.
>• XX Ib of sediment removed from stormwater
catch basins each year.
>• XX Ib of pollutant(s) of concern removed
by properly functioning stormwater BMPs
(modeled).
BMPs, stormwater outfalls, and other stormwater
infrastructure. This system helps the MS4 to track
BMP installation; prioritize maintenance activities;
and document program compliance.
Land Use/Land Cover (Section 10.8.)
Land use/land cover is an important measure
of success because it can help guide program
decisions regarding future zoning, management
practices, and habitat protection decisions.
Water Resources Monitoring and Modeling
(Section 10.9)
Water resources indicators measure the health of
waterbodies directly (e.g., in-stream monitoring)
or indirectly (e.g., water quality modeling). Water
quality monitoring and modeling, conducted by the
MS4 or another entity (e.g., federal or state agency,
watershed association, university) are essential to
gauge the success of the program.
Subsequent sections of this chapter describe these
indicators in more detail.
10.6. Program Indicator Tracking
Program indicator tracking is an accounting of program
measures and milestones taken by the MS4 to achieve
its goals. Program tracking also includes an internal
tracking system to guide the plan review process.
Program Measures and Milestones
Measures and milestones are the activities required
in the stormwater program's NPDES permit or activi-
ties set as measurable goals. The tracking system acts
as a checklist of items accomplished, and it is useful
in annual reporting and as a direct measure of the
program's progress overtime. Example measures
include the following:
Completion of a post-construction program self-
assessment (see Tool 1)
• Enactment of a stormwater ordinance
Development or adaptation of a stormwater
guidance manual (see Tool 5)
Development of a stormwater plan review process
Number of post-construction plans reviewed
Number and type of structural post-construction
BMPs installed
Number and type of non-structural post-
construction BMPs installed
Number of inspections of post-construction BMPs
conducted during initial BMP installation
Number of post-construction BMPs inspected for
maintenance
• Number of post-construction BMPs maintained
• Sediment removed from BMPs and storm drain
inlets
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Chapter 10: Tracking, Monitoring, and Evaluation
Table 10.2. Indicators of Post-Construction Stormwater Program Success
Base Indicators Recommended for all
Programs
Supplemental Indicators/Records3
Program
Indicators
Date of ordinance adoption/revision
Number of plans reviewed
>• Number and type of post-construction BMPs
approved on plans
>• Number of staff dedicated to program; dates
of staff hiring
Budget amount dedicated to the program.
Number of BMP installation/maintenance
inspections
>• Frequency of maintenance inspections based
on BMP type or priority
Number of practices maintained
Number of maintenance actions
>• Watershed plan development
Average plan review time
>• Collection of plan review fees, amount
collected, allocation of revenues
Pounds of sediment and trash removed from
stormwater practices
Public awareness of stormwater issues (as
measured by a survey)
Stormwater
Infrastructure
Numberand location of all outfalls
Number and location of installed post-
construction BMPs
Drainage and stormwater maintenance
easement maps.
Numberand location of BMPs requiring
maintenance.
— Routine
— Structural/repair
— Emergency/high-priority
>• Map of storm drain infrastructure
>• Number, location, and condition of LID
practices
Detailed data from maintenance reports, such
as:
— Number of practices with sediment
accumulation > 50% of capacity
— Number of practices with failing
embankments
— Number of practices with clogged filter
beds
Land Use/Land
Cover
Impervious cover
>• Land use
Land cover
Total area developed
Zoning
>• Assessment of key habitat factors
Location of key habitat areas/special
resources
Acres of forest/meadow/prairie preserved
during development
Numberand type of stormwater hotspots
Monitoring and
Modeling
Water quality conditions from available
monitoring and modeling (e.g.,TMDLs, state,
university, volunteer monitoring)
Annual pollutant load from the MS4
(modeled)
>• Average pollutant concentrations (in-stream
monitoring)
>• Habitat scores from stream assessments
Pollutant removal of individual practices
(monitored)
' The items in this column serve only as examples; the list is not exhaustive. Indicators should be customized by the specific program.
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Chapter 10: Tracking, Monitoring, and Evaluation
Many of these measures are simply checklist items
(e.g., "enactment of a stormwater ordinance") that
require no detailed data tracking. Other measures,
however, require ongoing record-keeping, usually by
several different departments within a community
(e.g., "sediment removed from storm drain inlets").
These measures will require significant coordination to
ensure that the desired data are collected on a regular
basis and in a usable format. (See Figure 10.2 for an
example.)
Plan Review Tracking
Most municipalities already have a system in place to
track their plan review process. Several commercial
systems are available, or a municipality can develop its
own database system. The primary purposes of these
plan review tracking systems are (1) to track the current
status of plans and where they are in the plan approval
process and (2) to ensure that all post-construction
requirements on submitted plans have been met. (See
Figure 10.3 for an example form used to collect and
track information about new development projects.)
The plan review tracking system can also be con-
structed to measure land use change overtime. If the
MS4 strives to use the tracking system in this way,
plan review forms and documentation need to be
customized to ensure that the desired data are readily
available. For example, if the form includes data like
the acres of forest and wetland disturbed or acres
of impervious cover created by a project, these data
can then be aggregated to characterize the land use
changes associated with new development within the
MS4.
See Chapter 7 for more information on the stormwater
plan review process.
Inlet Cleaning
12,000 -
Number of Inlets
Inlets-Volume
V
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Figure 10.2. Inlet cleaning data derived from maintenance records
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Chapter 10: Tracking, Monitoring, and Evaluation
City of San Diego
Development Services
1222 First Ave., MS-302
San Diego, CA 92101
(619)446-5000
FORM
Storm Water Requirements DS-560
Applicability Checklist
MARCH 2008
Project Address:
Assessor Parcel Number(s):
Project Number (for City Use Only)
Complete Sections 1 and 2 of the following checklist to determine your project's permanent and construction storm water best
management practices requirements. This form must be completed and submitted with your permit application.
Section 1 - Permanent Storm Water BMP Requirements:
If any answers to Part A are answered "Yes," your project is subject to the "Priority Project Permanent Storm Water BMP Re-
quirements," and "Standard Permanent Storm Water BMP Requirements" of the Storm Water Standards Manual. Section III,
"Permanent Storm Water BMP Selection Procedure." If all answers to Part A are "No," and any answers to Part B are "Yes,"
your project is only subject to the Standard Permanent Storm Water BMP Requirements. If every question in Part A and B is
answered "No," your project is exempt from permanent storm water requirements.
Part A: Determine Priority Project Permanent Storm Water BMP Requirements.
Does the project meet the definition of one or more of the priority project categories?*
1. Detached or attached residential development of 10 or more units —I Yes LJ No
2. Developments of heavy industy greater than 1 acre —I Yes LJ No
Commercial development greater than 1 acre LJ Yes —I No
4. Automotive repair shop '—I Yes '—I No
5. Restaurant LJ Yes LJ No
6. Hillside development greater than 5,000 square feet —I Yes —J No
7. Project within, directly adjacent to or discharging to receiving waters within Water Quality
Sensitive Areas.... ....IJ Yes LJ No
8. Parking lots greater than or equal to 5,000 square feet or with at least 15 parking spaces, and
potentially exposed to urban runoff IJ Yes —I No
9. Streets, roads, highways, and freeways which would create a new paved surface
that is 5,000 square feet or greater
..U Yes Q No
10. Significant redevelopment over 5,000 square feet LJ Yes LJ No
11. Retail gasoline outlets LJ Yes LJ No
" Refer tn the definitions section in the Storm Water Standards far expanded definitions of the priority project categories.
Limited Exclusion: Trenching and resurfacing work associated with utility projects are not considered priority projects. Park-
ing lots, buildings and other structures associated with utility projects are priority projects if one or more of the criteria in Part
A is met. If all answers to Part A are "No", continue to Part B.
Part B: Determine Standard Permanent Storm Water Requirements.
Does the project propose:
1. New impervious areas, such as rooftops, roads, parking lots, driveways, paths and sidewalks? LJ Yes LJ No
2. New pervious landscape areas and irrigation systems? LJ Yes LJ No
3. Permanent structures within 100 feet of any natural water body? LJ Yes LJ No
4. Trash storage areas? —I Yes —I No
5. Liquid or solid material loading and unloading areas? LJ Yes LJ No
6. Vehicle or equipment fueling, washing, or maintenance areas? LJ Yes LJ No
Figure 10.3. The City of San Diego's plan review process tracking form
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Chapter 10: Tracking, Monitoring, and Evaluation
Useful references for program tracking include the
following:
California Stormwater Quality Association (CASQA),
Municipal Stormwater Program Effectiveness Assessment
Guidance, 2007: www.casqa.org
Center for Watershed Protection, Smart Watershed
Benchmarking Tool: www.cwp.org
10.7. Stormwater Infrastructure Tracking
The Stormwater infrastructure tracking system is a
map-based database that tracks the location and
condition of BMPs, outfalls, conveyance structures,
and other Stormwater infrastructure attributes. This
tracking system should include a field inspection and
survey program for Stormwater infrastructure. The
tracking system is integral to the Stormwater program
for the following reasons:
Detailed knowledge of Stormwater practice
location and condition is needed to ensure ongoing
maintenance.
Long-term condition and performance of specific
BMPs and BMP design elements can help to inform
the future BMP design process.
BMP condition can reflect the effectiveness of the
program.
Integration of BMP data with land use data can be
used to develop models that estimate pollutant
removal on a watershed- or MS4-wide basis (see
Section 10.9).
• As a supplemental benefit, mapping of outfalls
and infrastructure will support the Illicit Discharge
Detection and Elimination (IDDE) program.
Because a Stormwater infrastructure inventory
program can be an ambitious and costly undertaking,
it can be phased over time. For instance, the program
can start with newly installed BMPs and major
outfalls, followed by older BMPs, minor outfalls, and
conveyance elements. Data should include a photo
log of infrastructure elements that are keyed to
markings made on the actual infrastructure elements
in the field.
All data entered into the database should be verified
and updated over time through field inspections.
For example, the quality of the location data can be
enhanced through the use of hand-held global posi-
tioning system (GPS) units during ongoing operation
and maintenance (O&M) activities, as well as when new
Stormwater infrastructure elements are added (see
Figure 10.4).
Figure 10.4. Global positioning systems (GPS) linked with geographic information systems (GIS) are excellent
tools for tracking Stormwater infrastructure
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Chapter 10: Tracking, Monitoring, and Evaluation
The specific data collected during field inspections can
be used to determine what percentage of practices
meet particular stormwater practice performance
goals, such as:
• Sediment forebays should be no more than half full
of sediment.
• Vegetation should cover at least 80% of the surface
area of bioretention and wetland BMPs.
Emergency spillways should be clear of debris and
obstructions.
Open channels should be stable (not eroding) and
free of sediment deposits.
These data are also used as triggers for when mainte-
nance should be performed by the municipality or the
responsible party (see Chapter 9).
In parallel with physical infrastructure mapping, the
MS4 needs a readily available, accurate, and preferably
digital mapping layer of any easements and property
boundaries. These data help in determining which
practices have adequate maintenance access, and they
help in identifying situations where a new agreement
with a private property owner is needed to conduct
regular inspections and maintenance.
10.8. Land Use/Land Cover Tracking
The ultimate effectiveness of any program needs to
be evaluated in the context of changing land use. In
addition, many of the codes and policies implemented
as a part of a post-construction stormwater program,
such as implementation of LID or open space design
techniques, can directly affect future land use. Con-
sequently, updating basic land use layers is critical to
understanding the actual benefits of the program.
Baseline data, including a good measure of impervi-
ous cover, land use, land cover, and developed areas,
should be developed early in the process. These data
should then be overlaid with zoning data or another
estimate of future land use. Taken together, these data
can help identify sensitive watersheds, as well as areas
of potential growth.
Ultimately, these data help to inform decisions about
redevelopment policies, zoning, and stormwater
criteria. They also help the community to understand
realistic pollutant reduction goals in the context of
existing land use and future development pressures.
Finally, these land use layers help the MS4 identify
areas for potential stormwater retrofits. (See Chapter 2
for more discussion on mapping and data needs to
build a program.)
These basic land use and land cover data can be
supplemented with additional data that can help the
MS4 better understand habitats and pollutant loading
potentials. Some examples include stream, wetland, or
forest assessments that identify high-value resources,
or locations of stormwater hotspots that identify key
pollutant load sources.
Land use and land cover data should be continuously
updated. A plan re view tracking system (Section 10.6)
can be a direct source of information, as long as the
existing and current land uses are accurately recorded
for each development plan. As these data are updated,
the MS4 can periodically reevaluate progress toward
watershed-wide goals identified at the program's
onset.
10.9. Water Quality Monitoring and Modeling
Tracking
Water Quality Monitoring
Water quality monitoring is the ultimate tool to mea-
sure the effectiveness of a stormwater program. Two
basic types of monitoring can be conducted:
1. Watershed Assessment Monitoring: This
monitoring takes place at the broad scale
of the watershed to establish baseline or
general conditions. Monitoring can consider a
range of indicators, including biological (e.g.,
macroinvertebrates, fish), physical (e.g., flow,
suspended sediment, stream channel stability),
and/or chemical (e.g., phosphorus, trace metals,
bacteria). Watershed assessment monitoring is
appropriate for all stages of program development,
but particularly in the planning stage to help
identify major water quality issues and threats.
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Chapter 10: Tracking, Monitoring, and Evaluation
2. Targeted Monitoring: Once general issues have
been identified, the program can undertake
targeted monitoring to identify particular source
areas, causes of elevated pollutant levels, or risks to
stream health. In this way, program resources can
also be targeted to actual land uses and sources that
are causing the problem. This type of monitoring
can focus on a few good water quality variables to
measure effectively, rather than trying to track a
long list of indicators. For example, monitoring for a
swimming beach that is impaired by bacteria should
monitor Ł coli at the swimming area, nearby storm
drain outfalls, and tributary streams.
Developing a program to conduct water quality
monitoring for a local stormwater program can
be challenging. Some of the significant challenges
include the following:
• The dynamic and variable nature of stormwater
quantity and quality is difficult to capture in a
stormwater monitoring program.
• Municipal stormwater programs usually encompass
large areas of land with multiple land uses and
many different outfalls to receiving waters.
Water quality monitoring programs, especially at a
large scale, can be expensive and staff-intensive.
It can be difficult to link a measured water quality
result to a BMP or action by the jurisdiction.
Some level of water quality monitoring is important
for post-construction programs. Depending on pro-
gram sophistication and level of funding, the MS4 may
develop a phased approach to monitoring, beginning
with relatively simple techniques (perhaps using citizen
volunteers) and progressing to more complex systems
(see the resources in Table 10.3). Other ideas are to pool
resources with other jurisdictions, local universities,
watershed groups, and/or relevant state agencies.
Another type of monitoring involves evaluating the
performance of selected BMPs. For example, if a
developer proposes a new BMP that the local program
staff is not familiar with, he or she can be asked
to conduct monitoring to demonstrate the BMP's
effectiveness. Tool 8: BMP Evaluation is designed to
help stormwater managers ask the right questions and
obtain the necessary monitoring data for verifying
BMP performance. Law et al. (2008) provides a study
design for monitoring the performance of individual
BMPs.
Water Quality Modeling
Water quality modeling can also be used to estimate
pollutant loads, and to measure progress based on
programs implemented by the MS4. Several models
are available, ranging from simple spreadsheet mod-
els to complex in-stream models. Unlike monitoring
data, water quality models are not a direct measure
of in-stream water quality. However, a simple, easily
updated model can provide enhancements to a moni-
toring program:
Models allow the community to forecast benefits
of a particular action, and they can be used to
customize measurable goals at the outset of the
permit cycle.
If data on land use and stormwater practices and
other relevant data are available, models can be
used to track progress over time.
• Unlike in-stream monitoring data, which are subject
to seasonal or annual weather conditions, models
can be used to predict progress without the "noise"
introduced by these climate variations.
Simplified models can be a relatively inexpensive
tool when compared with the level of monitoring
data needed to detect trends in water quality.
Table 10.3 presents some monitoring and modeling
resources available from various organizations.
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Table 10.3. Monitoring and Modeling Resources for Municipal Stormwater Programs
General Water
Quality Monitoring
Stormwater
Monitoring
BMP performance
monitoring
Pollutant Load
Models
Overall Monitoring
Guidance
USEPA, Monitoring Guidance for Determining the Effectiveness of Nonpoint Source Controls
(Sept. 1997, EPA 841-B-96-004).
USDh-NRCS, National Handbook of Water Quality Monitoring
http://gmnde.nal.usda.gov/wqic/cgi-bin/retrieve_wq_record.pl?rec_id=1015
Several resources for volunteer monitors available at: www.epa.gov/owow/monitoring/volunteer
Southern California Coastal Water Research Project, Model Monitoring Program for Municipal Separate
Storm Sewer Systems in Southern California
ftp://ftp.sccwrp.org/pub/download/PDFs/419_smc_mm.pdf
Dr. Robert Pitt, University of Alabama, National Stormwater Quality Database
http://rpitt.eng.ua.edu/Research/ms4/Paper/Mainms4paper.html
USEPA, Urban BMP Performance Tool
http://cfpub.epa.gov/npdes/stormwater/urbanbmp/bmpeffectiveness.cfm
USEPA, ASCE, etal.. International Stormwater BMP Database, Urban Stormwater BMP Performance
Monitoring: A Guidance Manual for Meeting the National Stormwater BMP Database Requirements
www.bmpdatabase.org
Center for Watershed Protection, Pollutant Removal Performance Database
www.cwp.org> Resources > Controlling Runoff & Discharges > Stormwater Management
Stormwater Manager's Resource Center, Environmental Indicator Profile Sheet: BMP Performance
Monitoring
http://www.stormwatercenter.net/intro_monitor.htm
USGS, SLAMM (Source Loading and Management Model)
http://wi.water.usgs.gov/slamm
Center for Watershed Protection, WTM (Watershed Treatment Model)
www.cwp.org > Resources > Watershed Management > Desktop Analysis
USEPA, BASINS (Better Assessment Science Integrating Point and Nonpoint Sources)
www.epa.gov/waterscience/basins/
Center for Watershed Protection, The Simple Method
http://www.stormwatercenter.net/intro_monitor.htm
Center for Watershed Protection, Monitoring to Demonstrate Environmental Results: Guidance to
Develop Local Stormwater Monitoring Programs Using Six Example Study Designs
www.cwp.org
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Chapter 10: Tracking, Monitoring, and Evaluation
10.10. Annual Reporting and Program
Inspections & Audits
Annual Reporting
All NPDES-permitted stormwater programs must
submit a report (typically, on an annual basis) docu-
menting activities in compliance with the permit. EPA's
Phase II regulations require that these annual reports
include the following:
Status of compliance with permit conditions
Assessment of the appropriateness and
effectiveness of the identified BMPs
Status of the identified measurable goals (see
Table 10.1)
• Results of information collected and analyzed,
including monitoring data submitted during the
reporting period
Summary of stormwater activities planned during
next reporting cycle
• Proposed changes to the Stormwater Management
Plan (SWMP), along with justification
Other entities responsible for implementing aspects
of the stormwater program
Change in people implementing and coordinating
the SWMP
The most common problem with annual reports is
that stormwater programs use them simply to report
activities and do not analyze the data to determine
whether program changes are necessary (i.e., the itera-
tive approach). For example, if the stormwater pro-
gram reports that it inspected 12 detention basins and
10 were in need of maintenance, the program should
assess and describe in the annual report why so many
needed maintenance. Perhaps it was the first time the
basins were inspected in many years, or the basins
might have been designed incorrectly. If necessary,
changes to the stormwater program should be made
to address any identified deficiencies.
The program can report findings using various tech-
niques. Figure 10.5 illustrates several examples; see
also the maintenance reporting examples in Table 10.1.
MS4 Audits
Regulatory agencies regularly conduct inspections
and audits of MS4 programs. The goal of those audits
is to assess compliance with NPDES permit conditions
(across all six minimum measures). This type of audit is
different from the post-construction program self-
assessment (Tool 1) described in Chapter 1, which can
be useful to help MS4 staff prepare for a regulatory
audit by assessing existing status of the stormwater
program and mapping out a future course and pro-
gram direction.
EPA has developed a guidance manual for state and
EPA staff on how to conduct MS4 audits (see MS4 Pro-
gram Evaluation Guidance available at www.epa.gov/
npdes/stormwater). Although the audience for this
manual is the parties conducting the audit, it is also
useful for MS4 staff to know what to expect and how
to prepare for an audit.
For stormwater programs that are audited by a
state regulatory agency or EPA (or their contractors),
Table 10.4 presents some tips on how to prepare.
The following are some common findings from past
MS4 audits conducted by EPA:
Inadequate standards to address post-construction.
Many MS4 audits have found post-construction
programs that lack specific standards or procedures
to adequately address post-construction runoff.
• Lack of an adequate stormwater planning
document. A stormwater management plan is the
document that guides all stormwater activities at a
municipal level; however, sometime these plans are
out-of-date or missing.
Inadequate measurable goals. Measurable goals are
supposed to be quantifiable and specific; however,
some municipalities use measurable goals as a
reporting measure but not a planning tool.
• Lack of stormwater pollution prevention plans
for municipal facilities. Municipal facilities often
conduct many activities that can affect stormwater
quality. A well-written plan helps identify practices
that minimize exposure of pollutants to runoff and
educate municipal staff on their use.
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Cease and Desist Referrals to RWQCB
Orders • 0%
2%
Job Memorandums
91%
Notice of
Violations
7%
A. Show results graphically (Source: County of Ventura, 2007).
New BMP retrofit just after construction.
New BMP retrofit after first storm.
B. Use photos to help illustrate activities (Source: County of Fairfax, 2003)
C. Use CIS data to show location or intensity of activity (Source: King County, WA, MS4 Annual Report)
Figure 10.5. Examples of how stormwater activities can be reported:
(A) graphically, (B) with photos, (C) with GIS data
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Table 10.4. Preparing for an MS4 Audit by a Regulatory Agency
Before the audit
Complete the program self-assessment (Tool 1).
Review NPDES permit requirements, program-specific measurable goals, and other program
commitments.
>• Analyze potential weaknesses and address them, to the extent possible, before the audit.
Brief municipal staff and management on the audit.
Review and organize stormwater records.
Visit municipal facilities to prepare them for an audit visit.
During the audit
Answer the auditors' questions truthfully.
>• Ask questions (What is their expectation? What are others doing?)
Be prepared to take auditors to municipal maintenance facilities and construction sites.
After the audit
Brief municipal staff and management on the results.
Begin addressing deficiencies found (even before the audit report is received).
Inadequate legal authority. Some municipalities
lack adequate legal authority to ensure program
implementation.
Although a regulatory audit can have negative
connotations for a local program, with the right
preparation and attitude, an audit can be transformed
into a beneficial experience. For example, it can
allow MS4 program staff to educate state and
EPA regulatory staff about the unique issues and
challenges they face in implementing the program,
and can highlight key accomplishments. The audit can
present an opportunity to educate elected officials
and department heads about the resources needed
to carry out a good stormwater program. It can also
be used as a catalyst to get various local departments
working together toward common stormwater goals.
Finally, the audit presents an opportunity to identify
key program gaps (e.g., record-keeping, enforcement,
inspections, and maintenance) and strategies to
strengthen the program. To realize these benefits, the
local program staff will have to allocate enough staff
time and resources to make the audit a meaningful
experience.
10-16
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