LEWIS PUBLISHERS
A CRC Press Company
Boca Raton London New York Washington, D.C.
Second Edition
Thomas N. Debo • Andrew J. Reese
Municipal
Stormwater
Management
© 2003 by CRC Press LLC

This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with
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No claim to original U.S. Government works
International Standard Book Number 1-56670-584-3
Printed in the United States of America 1 2 3 4 5 6 7 8 9 0
Printed on acid-free paper

Library of Congress Cataloging-in-Publication Data

Debo, Thomas, N. (Thomas Neil), 1941–
Municipal stormwater management / Thomas N. Debo, Andrew J. Reese. –– 2nd ed.
p. cm.
Updated ed. of: Municipal storm water management. c1995.
Includes bibliographical refrences and index.
ISBN 1-56670-584-3 (alk. paper)
1. Urban runoff––Management. I. Reese, Andrew J. II Debo, Thomas N. (Thomas
Neil), 1941– Municipal storm water management. III. Title.
TD657 .D43 2002
2002030199

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Preface

The field of municipal stormwater management has expanded to the extent that it would
take many volumes to exhaustively cover the subject. But, in the day-to-day design and
management of the stormwater system, the engineer, planner, or administrator should not
need to resort to a large number of documents to find needed information. It should be
readily available in one spot, carefully explained where necessary, but not overly cluttered
with detailed theory and derivation. That is the approach and major aim of this book.
From a technical design standpoint, the authors combed the literature to find and present
clear treatments of each of the key design situations the practitioner will encounter. A

wealth of knowledge was compiled from federal, state, and local design publications. In
each case, the authors attempted to provide a stand-alone discussion, including all relevant
charts, figures, tables, and example applications. In addition, much original information
gathered from experience in many cities and counties is included.
To properly understand and manage stormwater requires more than a knowledge of
design procedures and hydrologic or hydraulic practice. Actually making it happen in a
real-world municipality, filled with the demands of regulations, financial pressures, stake-
holder groups, and politics, is also an important part of stormwater management. While
harder to quantify, the tools and understanding necessary for institutional, as well as
technical, success are also included in this book. They are derived from literally hundreds
of experiences and projects in cities and counties across the United States. A careful reading
will provide a wealth of information and principles and a sense of what works and what
does not.
Stormwater management is a fast-evolving field. Any treatment of it is only a snapshot
of a changing picture. The authors included the most up-to-date information available in
each of the key areas of the practice, including water quality best management practices
and stormwater master and quality management plans. Also gathered and included are
little known but valuable tables, charts, and procedures covering common designs and
more specialized situations. English and metric versions of charts and nomographs are
included where available and where deemed useful for the designer. The evolution of
stormwater management, as any science or practice, builds on basic understandings and
concepts. In each case, the authors attempted to provide, first, sufficient discussion to lay
a foundation and framework upon and within which any new developments can be built.
The book is primarily designed for use by engineers, designers, and planners involved
in municipal stormwater management. Information contained should cover most of the
design applications within urban areas and most of the institutional aspects of stormwater
management the planner or administrator faces daily. The book has also been designed
to be applicable to civil and environmental undergraduate and graduate courses from
planning or administration and engineering perspectives.
In addition to a general update of all information in the book, the major additions in

this edition of the book are updated information on water quality best management
practices, additional hydrology information, and new discussions related to the institu-
tional aspects of urban stormwater management.

Thomas N. Debo
Andrew J. Reese

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© 2003 by CRC Press LLC

Authors

Dr. Thomas N. Debo

is Professor Emeritus in the City Planning Program in the College
of Architecture at the Georgia Institute of Technology and president of Debo & Associates,
Inc., a consulting firm specializing in the urban stormwater management area.
He received his B.S. in Civil Engineering from Michigan Technological University in
1963 and his Master of City Planning and Ph.D. in Civil Engineering from the Georgia
Institute of Technology in 1972 and 1975, respectively. He has over three decades of
experience dealing with stormwater management, including development of hydro-
logic/hydraulic computer programs, engineering design handbooks, local ordinances and
policies, and technical and engineering studies and designs. He has worked with numer-
ous municipalities throughout the United States, state and federal agencies, and a large
number of consulting and legal firms, and has extensive experience as an expert witness
related to urban stormwater management issues. Dr. Debo has published several books
and over 40 articles in professional journals and other publications. He has been very
active in conducting stormwater-related workshops throughout the country and has been
invited to give presentations and speeches extensively throughout the United States and
several European countries. In recent years, Dr. Debo has been involved with the design

and implementation of innovative techniques for the capture and reuse of urban storm-
water and improvement of stormwater quality. He is a member of the American Society
of Civil Engineers and a registered engineer in the State of Georgia. Dr. Debo is married
and the father of four daughters and four grandchildren and presently resides in Atlanta,
Georgia, and Morganton, North Carolina.

Andrew J. (Andy) Reese

has over 27 years’ experience in a wide variety of stormwater
and water resource engineering and management roles.
In those years, he worked in a hydraulic and hydrologic research position with the
Corps of Engineers, and then as a consultant. He has served in roles from site design,
FEMA studies, master planning, stable channel design and sediment transport, hydraulic
structures design, design criteria manual development, NPDES permitting, training, com-
puter modeling and software development, public education programs, meeting facilita-
tion, stormwater utility development, BMP programs, and numerous stormwater program
assessments. He has managed many large and complex municipal stormwater projects.
His experiences with well over 100 local governments in 48 states and for numerous state
and federal agencies give him a unique view of stormwater management as it is practiced
in the United States. He has been involved in the establishment of some of the most
successful stormwater programs in the United States.
Reese has written and presented over 50 papers nationally and internationally on various
stormwater-related subjects from complex modeling to program development, public
involvement, and stormwater overviews. He is also a popular speaker and teacher, annu-
ally giving many presentations and short courses across the United States and interna-
tionally for national and regional conventions. He has master’s degrees in business
administration and hydraulic engineering. Reese is vice president for AMEC Earth &
Environmental, Inc., a large international water resources, environmental, and geotechni-
cal consulting firm. He is a registered professional engineer and hydrologist. He is married
and the father of four teenagers residing near Nashville, Tennessee.


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© 2003 by CRC Press LLC

Contents

1

Introduction to Municipal Stormwater Management

1.1 Stormwater Management Paradigms
Early Stormwater Paradigms
Paradigm #1 — Run It In Ditches
Paradigm #2 — Run It In Pipes
Paradigm #3 — Run It In Stormwater Pipes
Paradigm #4 — Keep It From Stormwater Pipes
Paradigm #5 — Well, Just Do Not Cause Flooding
The New Breed of Stormwater Paradigms
Paradigm #6 — Do Not Pollute
Paradigm #7 — It Is The Ecology
Paradigm #8 — Water Is Water Is Watershed
Paradigm #9 — Green And Bear It
From Paradigm To Paradigm
1.2 Understanding Stormwater Management Problems and Solutions
1.3 The Organization of the Rest of the Book
References

2

Stormwater Management Programs


2.1 The Stormwater Management Program
2.2 Functional Perspective of Stormwater Management
Long-Range Aspects
Day-to-Day Stormwater Management
2.3 Overview of the Legal Aspects of Stormwater Management
2.4 Overview of the Technical Aspects of Stormwater Management
Technical Manuals
Computer Models
Databases and Infrastructure Inventories
Mapping, GIS, and Related
GIS Systems
2.5 Overview of the Organizational Aspects of Stormwater Management
2.6 Overview of the Financial Aspects of Stormwater Management
2.7 Typical Stormwater Management Problem Areas
Long-Term Problem Areas
Legal/Financial/Organizational/Technical Underpinning Problem Areas
Day-to-Day Problem Areas
2.8 Three Example Programs
Charlotte, North Carolina
Louisville MSD, Kentucky
Tulsa, Oklahoma
2.9 Characteristics of Successful Programs
Public Education and Involvement
Key Champions
Financing

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Basin-Wide Planning and Control
Clear Procedures and Goals
Focused Authority
Strong Technical Guidance and Capabilities
Guided Development
Comprehensive Maintenance
An Environmental Focus
2.10 The Stormwater Program Feasibility Study
2.11 Floodplain Management
Flood Insurance Programs
Reference

3

Public Awareness and Involvemen

3.1 Introduction
3.2 Defining the “Public”
3.3 Plan to Include the Public
3.4 Public Involvement and Education Techniques
Public Participation
Public Participatory Groups
3.5 The Stormwater Advisory Committee
Defining the Group
Media and the General Public
Authority and Purpose
Defining the Issues
Informed Consent and Consensus Building
Ground Rules and Objective Criteria
Policy Papers

3.6 Volunteer Programs
3.7 Dealing with the Media
3.8 Risk Communications
3.9 Technical Communications
References

4

Ordinances, Regulations, and Documentation

4.1 Introduction
4.2 Legal Basis and Considerations
Watercourse Law
Riparian Doctrine
Prior Appropriation Doctrine
Diffused Surface Water Law
Common Enemy Doctrine
Civil Law Doctrine
Reasonable Use Doctrine
Liability and Damages
Individual Liability
Municipal Liability
“Takings”
Water Quality and Water Law
4.3 Municipal Ordinances
Legal Authority and Context

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Technical Basis
Administrative Apparatus
Enforcement Provisions
Special Water-Quality Considerations
Detention
4.4 Drafting Local Ordinances and Regulations
Identify Problems and Issues
Formulation of Objectives
Developing Policies
Detention Analysis Example
Drafting the Ordinance
Stormwater Management Design Manual
4.5 Flexibility in a Stormwater Management Program
Flexible Ordinance Provision
Rigid Ordinance Provision
4.6 When to Adopt an Ordinance
4.7 The Complete Stormwater Management Program
Land-Use Planning Aspects
Municipal Role in Encouraging Innovative Solutions
Administrative Problems
Technical Requirements
Staff and Financial Resources Needed
Field Inspection
Enforcement
Legal Considerations
Summary
4.8 Documentation
Purpose of Documentation
Types of Documentation
Preconstruction

Design
Construction or Operation
Documenting the Plan Development Process
Documentation Procedures
Storage Requirements
Specific Content of Documentation Files
Hydrology
Bridges
Culverts
Open Channels
Storm Drains
Storage Facilities and BMPs
Pump Stations
4.9 Documentation for Legal Proceedings
References

5

Financing Stormwater Management Programs

5.1 Financing Needs of Stormwater Management Programs
5.2 Major Stormwater Funding Methods
5.3 Stormwater Utility Overview
Overview of the Concept

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© 2003 by CRC Press LLC

Advantages of the Utility Concept
Uniqueness Factor

5.4 Utility Funding Methods
5.5 Stormwater Utility Policy Issues
General Policy Information
Stormwater Credits
5.6 Steps in a Typical Financing Study
Overview
The Program Track
The Public Track
The Finance Track
The Data Track
Feasibility Studies
5.7 Typical Financing Feasibility Study Scope of Services
Purpose
Task 1 — Development of a Citizens Group
Task 2 — Stormwater Program Description, Problems, and Needs
Deliverables
Task 3 — Program Objectives and Priorities
Deliverables
Task 4 — Projected Stormwater Program
Deliverables
Task 5 — Basic Funding Feasibility
Deliverables
Task 6 — Service Charge Billing, Collection, and Accounting Options
Deliverables
Task 7 — Public Communications Program
Deliverables
Task 8 — Action Plan Report
Deliverables
References
Appendix A — Financing Stormwater Management Programs


6

Data Availability and Collection

6.1 Overview
Introduction
Data Collection Effort
6.2 Sources and Types of Data
Data Categories
6.3 Major Data Topics
Watershed Characteristics
Contributing Size
Slopes
Watershed Land Use
Streams, Rivers, Ponds, Lakes, and Wetlands
Roughness Coefficients
Stream Profile
Stream Cross Sections
Existing Structures
Flood History

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Debris and Ice
Scour Potential
Controls Affecting Design Criteria
Downstream Control
Upstream Control

6.4 Data Acquisition, Survey Information, and Field Reviews
Remote Data Acquisition
Geographical Information Systems
Telemetry
Survey Information
Field Reviews
6.5 Data Evaluation
Data Accuracy
Sensitivity Studies
Statistical Analysis
Time Series Analysis
Extreme Event Analysis
Geostatistical Analysis
Other Statistical Methods
6.6 Precipitation Data Collection
Overview
Data Collection
Factors Influencing Data Collection
Storm Types
Storm Movement
Storm Decay
Precipitation Data Acquisition
Rain Gauges
Radar Precipitation Data Acquisition
Rain Gauging Networks
Rainfall Average Depth Estimation
6.7 Flow Data Collection
Introduction
Basic Equipment and Techniques Overview
Common Errors

6.8 Flow Data Collection — Natural Controls
Selection of Gauging-Station Sites
Velocity Measurements
Velocity Meters
6.9 Flow Data Collection — Tracer Methods
Salt-Velocity Method
Salt or Color-Dilution Methods
6.10 Environmental Data Considerations and Collection
Data Needs
Environmental Sampling Objectives
Typical Sampling Program Steps
Key Constituents
Metals
Nutrients
Human Pathogens
Oxygen Demand

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© 2003 by CRC Press LLC

Sediment
Oil and Grease
Pollution Sources
Erosion and Sedimentation
Atmospheric Fallout
Vehicles
Other Human Activities
Impacts on Receiving Waters
Land-Use Baseline Data
Urban Runoff Quality Data Collection

Site Selection
Storm Event Sampling
Sample Types
References
Appendix A — Sources of Data
Appendix B — Field Investigation Form and Checklist

7

Urban Hydrology

7.1 Introduction
7.2 Concept Definitions
7.3 Hydrologic Design Policies
Drainage Basin Characteristics
Stream Channel and Conveyance System Characteristics
Floodplain Characteristics
Meteorological Characteristics
7.4 Design Frequency and Risk
Risk
Risk-Based Analysis
Design Frequency
Cross Drainage
Storm Drains
Inlets
Detention and Retention Storage Facilities
Review Frequency
7.5 Hydrologic Procedure Selection
Analysis of Stream Gauge Data
Regression Equations

Rational Method
Unit Hydrograph Methods
Synder’s Unit Hydrograph
SCS Synthetic Unit Hydrograph
Continuous Simulation Models
Summary
7.6 Calibration
7.7 Precipitation and Losses
Intensity–Duration–Frequency Curves
Rainfall Durations and Time Distributions
Duration
Distribution
Example Information
The “Balanced-Storm Approach”

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SCS 24-Hour Storm
Huff Distributions
Yen and Chow’s Method
7.8 Rational Method
Rational Formula
Characteristics and Limits of the Rational Method
Time of Concentration
Rainfall Intensity
Drainage Area
Runoff Coefficient
Example Problem — Rational Method
7.9 SCS Hydrologic Methods

Basic Equations and Concepts
Rainfall–Runoff Equation
Curve Number
Antecedent Moisture Conditions
Connected Impervious Areas
Unconnected Impervious Areas
Composite Curve Numbers
Rainfall
Calculation of Lag Time and Time of Concentration
Travel Time and Time of Concentration Empirical Equation
Travel Time and Time of Concentration — Manning’s Equation
Drainage Area
Procedures, Tables, and Figures
SCS Peak Discharges
Computations
Limitations
SCS Peak Discharge Example
SCS Hydrograph Generation
Rainfall Excess Using SCS Methods
Rainfall Excess Example
SCS Dimensionless Unit Hydrographs
Dimensionless Unit Hydrograph Discussion
Unit Hydrograph Applications
Unit Hydrograph Example
7.10 Santa Barbara Urban Hydrograph Method
Example: 10-Acre Site — Existing Conditions
Input Data
Output Table — 24-Hour Storm (Table 7-31)
Example: 10-Acre Site — Developed Conditions
Input Data

Output Table — 24-Hour Storm
7.11 Water-Quality Volume and Peak Flow
Water-Quality Volume Calculation
Water-Quality Volume Peak Flow Calculation
7.12 Channel Protection Volume Estimation
Basic Approach
7.13 Water Balance Calculations
Basic Equations
Rainfall (P)

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Runoff (Ro)
Baseflow (Bf)
Infiltration (I)
Evaporation (E)
Evapotranspiration (Et)
Overflow (Of)
7.14 Downstream Hydrologic Assessment
Reasons for Downstream Problems
Flow Timing
Increased Volume
The Ten-Percent Rule
References

8

Storm Drainage Systems


8.1 Introduction
8.2 Concept Definitions
8.3 Pavement Drainage
Design Steps
Design Factors
Return Period
Spread
Inlet Types and Spacing
Longitudinal Slope
Cross Slope
Curb and Gutter Sections
Roadside and Median Channels
Bridge Decks
Shoulder Gutters
Median/Median Barriers
Storm Drains
Detention Storage
Costs
8.4 Stormwater Inlet Overview
8.5 Design Frequency and Spread
8.6 Gutter Flow Calculations
Uniform Cross Section
Composite Gutter Sections
8.7 Grate Inlet Design
Grate Inlets on Grade
Grate Inlet in Sag
8.8 Curb Inlet Design
Curb Inlets on Grade
Curb Inlets in Sump
8.9 Combination Inlets

8.10 Energy Losses in a Pipe System
Friction Losses
Velocity Headlosses
Entrance Losses
Junction Losses — Incoming Opposing Flows
Junction Losses — Changes in Direction of Flow
Junction Losses — Several Entering Flows

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8.11 Storm Drains
Formulas for Gravity and Pressure Flow
Hydraulic Grade Line
Hydraulic Grade Line Design Procedure
8.12 Environmental Design Considerations
Roadway Pollution
Structural Roadway BMP Design Overview
References
Appendix A — Metric Design Figures

9

Design of Culverts

9.1 Introduction
9.2 Concept Definitions
9.3 Culvert Design Steps and Criteria
Design Steps
Determine and Analyze Site Characteristics

Perform Hydrologic Analysis
Perform Outlet Control Calculations and Select Culvert
Perform Inlet Control Calculations for Conventional
and Beveled-Edge Culvert Inlets
Perform Throat-Control Calculations for Side- and Slope-Tapered
Inlets (Optional)
Analyze the Effect of Falls on Inlet Control Section Performance (Optional)
Design Side- and Slope-Tapered Inlets (Optional)
Complete File Documentation
Engineering and Technical Design Criteria
Flood Frequency
Velocity Limitations
Buoyancy Protection
Length and Slope
Debris Control
Ice Buildup
Headwater Limitations
Tailwater Conditions
Storage — Temporary or Permanent
Culvert Inlets
Projecting Inlets or Outlets
Headwalls with Bevels
Improved Inlets
Commercial End Sections
Inlets with Headwalls
Wingwalls and Aprons
Improved Inlets
Material Selection
Culvert Skews
Culvert Sizes and Shapes

Weep Holes
Outlet Protection
Erosion and Sediment Control
Environmental Considerations

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Safety Considerations
9.4 Culvert Flow Controls and Equations
Design Equations
Critical Depth — Outlet Control
Tailwater Depth — Outlet Control
Tailwater Depth > Barrel Depth — Outlet Control
Tailwater < Barrel — Outlet Control
Tailwater Insignificant — Inlet Control
Inlet or Outlet Control
9.5 Design Procedures
Tailwater Elevations
Use of Inlet- and Outlet-Control Nomographs
Storage Routing
9.6 Culvert Design Example
Input Data
9.7 Long-Span Culvert
9.8 Design of Improved Inlets
Bevel-Edged Inlet
Side-Tapered Inlet
Slope-Tapered Inlet
Improved Inlet Performance
9.9 Design Procedures for Bevel-Edged Inlets

Design Figure Limits
9.10 Flood Routing and Culvert Design
Design Procedure
9.11 HY8 Culvert Analysis Microcomputer Program
References
Appendix A
Appendix B

10

Open Channel Design

10.1 Introduction
10.2 Design Criteria
Channel Types
Vegetative Linings
Flexible Linings
Rigid Linings
Rigid Low-Flow Channels
General Design Criteria
Channel Transitions
10.3 Hydraulic Terms and Equations
Flow Classification
Hydraulic Terms and Definitions
Total Energy Head
Specific Energy
Kinetic Energy Coefficient
Steady and Unsteady Flow
Uniform Flow and Nonuniform Flow
Gradually Varied and Rapidly Varied

Froude Number

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Critical Flow
Subcritical Flow
Supercritical Flow
Hydraulic Jump
Equations
Manning’s Equation
Continuity Equation
Energy Equation
10.4 Manning’s n Values
Natural Channels
10.5 Manning’s n Handbook
10.6 Best Hydraulic Section
10.7 Uniform Flow Calculations
Direct Solution
General Solution Nomograph
Trapezoidal Solution Nomograph
Trial-and-Error Solution
Irregular Channels
Average Roughness
Irregular Channel Calculations
10.8 Critical-Flow Calculations
10.9 Vegetative Design
Design Stability
Design Capacity
Erosion Control

10.10 Approximate Flood Limits
100-Year Flood Elevation
Setback Limits
10.11 Uniform Flow — Example Problems
Direct Solution of Manning’s Equation
Irregular Channel (Example 1)
Grassed Channel Design Stability (Example 2)
Grassed Channel Design Capacity (Example 3)
10.12 Gradually Varied Flow
Direct Step Method
Standard Step Method
10.13 Gradually Varied Flow — Example Problems
Direct Step Method
Standard Step Method
10.14 Hydraulic Jump
10.15 Channel Bank Protection
Riprap Design
Riprap Design Example
Grouted Riprap
Gabions and Rock Mattresses
Soil Cement
Bioengineering
Manufactured Bank-Protection Methods
10.16 Physical Stability of Channels
Overview
Channel Response to Change

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Proportionality Approaches
Assessing Stream Stability
Stable Channel Design Approaches
Maximum Permissible Velocity Method
Tractive Stress Method
Regime Equations for Channel Proportions
Simons and Albertson Equations
Gravel Bed Equations
Analytical Methods for Channel Proportions
Neill Method
Stable Channel Design Examples
Permissible Velocity Example
Tractive Stress Design Example
Regime Equation Example
Neill Relations
Stream Structures
Grade Control Structures
Sills
Drop Structures, Chutes, and Flumes
10.17 Environmental Considerations for Channels
Instream Mitigation Features
Riprap and the Environment
Environmental Consideration of Floodplains
Floodplain Environmental Activities
Greenway Planning
Stream Channel Preservation and Restoration
Restoration Guiding Principles
Preserve and Protect Aquatic Resources
Restore Ecological Integrity
Restore Natural Structure

Restore Natural Function
Work within the Watershed and Broader Landscape Context
Understand the Potential of the Watershed
Address Ongoing Causes of Degradation
Develop Clear, Achievable, and Measurable Goals
Use a Reference Site
Involve the Skills and Insights of a Multidisciplinary Team
Design for Self-Sustainability
Use Passive Restoration, when Appropriate
Use Natural Fixes and Bioengineering Techniques, where Possible
Monitor and Adapt where Changes are Necessary
Restoration Practices
Stream Health Assessment
References

11

Storage and Detention Facilities

11.1 Introduction
11.2 Uses and Types of Storage Facilities
Uses of Storage Facilities
Types of Storage Facilities

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11.3 Design Criteria
General Design Criteria
Specific Detention Design Criteria

Specific Retention Design Criteria
Outlet Works Design Criteria
Location Design Criteria
11.4 Safe Dams Act
Category 1
Category 2
Category 3
11.5 General Design Procedure for Storage Routing
Stage–Storage Curve
Stage–Discharge Curve
General Procedure
11.6 Outlet Hydraulics
Combination Outlets
Perforated Risers
Two-Way Drop Inlets
Weirs
Sharp-Crested Weirs
Submerged Weir Correction
Approach Velocity Correction
Sharp-Crested Rectangular Weirs
Trapezoidal and Cipolletti Weirs
V-Notch Weirs
Broad-Crested Weirs
Submergence Effects
Triangular Channel Broad-Crested Weirs
Ogee Shapes
Special Weirs
Side-Channel Weirs
Example of Side-Channel Weir
Orifice Meters and Nozzles

Drop Inlet Boxes
Rooftop Detention
Example Rooftop Design
Modified Rational — Mass Balance Method
Drywells for Roof Drains
Detention Chambers and Pipes
Parking Lot Detention
Porous Pavement
Pipes and Culverts
Combination Outlets
Multistage Outlet Design Procedure
11.7 Extended Detention Outlet Design
Example Outlet Design
Method 1: Maximum Hydraulic Head with Routing
Method 2: Average Hydraulic Head and Average Discharge
Extended-Detention Outlet Protection
11.8 Preliminary Detention Calculations
Alternative Method

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Peak Flow Reduction
11.9 Routing Calculations
11.10 Example Problem
Preliminary Volume Calculations
Design and Routing Calculations
Downstream Effects
11.11 “Chainsaw Routing” Technique for Spreadsheet Application
Overview

Stage–Storage
Chainsaw Routing
Numerical Instability
11.12 Modified Rational Method Detention Design
Example Problem
11.13 Hand-Routing Method for Small Ponds
Limitations
Basic Approach Overview
Emergency Spillway Approximation
Details of Approach
Design Example — Sizing of a Small Pond for Orifice Flow
Step 1 — Input Data

.

Step 2 — Basic Calculations
Step 3 — Preliminary Estimates
Step 4 — Routing Number
Step 5 — Orifice Size and Other Data
Step 6 (Optional) — Recalculate Routing Number
Step 7 (Optional) — Recalculate R and Other Data
Step 8 — Emergency Spillway Approximation
Method Comparison
11.14 Land-Locked Retention
11.15 Retention Storage Facilities
11.16 Retention Facility Example Problem
11.17 Construction and Maintenance Considerations
11.18 Protective Treatment
Trash Racks and Safety Grates
References


12

Energy Dissipation

12.1 Introduction
12.2 Recommended Energy Dissipators
12.3 Design Criteria
Dissipator Type Selection
Ice Buildup
Debris Control
Flood Frequency
Maximum Culvert Exit Velocity
Tailwater Relationship
Material Selection
Culvert Outlet Type
Safety Considerations
Weep Holes

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12.4 Design Procedure
Data Needs
Procedure Outline
12.5 Local Scourhole Estimation
12.6 Riprap Aprons
Design Procedure
Design Considerations
Example Problems

Example 1 — Riprap Apron Design for Minimum Tailwater Conditions
Example 2 — Riprap Apron Design for Maximum Tailwater Conditions
12.7 Riprap Basin Design
Design Procedure
Design Considerations
Example Problems
Example 1
Example 2
Example 3
12.8 Baffled Outlets
Design Procedure
Example Problem
12.9 Downstream Channel Transitions
12.10 Energy Dissipator Computer Model
References

13

Structural Best Management Practices

13.1 Introduction
13.2 Surface Waters, Pollution, and Mitigation Measures
Surface Water Drivers for BMP Usage
Pollution Dynamics
Pollution Accumulation
Urban Hot Spots
Pollution Movement Forces
Pollution Availability and Fate
Stressors Associated with Urban Runoff
Overall Approach: Structural and Nonstructural BMPs

BMPs and Disease Vectors
13.3 Estimation of Pollutant Concentration and Loads
Pollutant Loads
Event Mean Concentrations
Nationwide Regression Equations Method
Example Application (Tasker and Driver, 1988)
The Simple Method
Acute or “Shock” Pollutant Loading Estimates
Simulation Models
13.4 BMP Design Concepts
Basis for Design Criteria for Structural BMPs
Unified Sizing Criteria
Stormwater Better Site Design
Unified Stormwater Sizing Criteria
Stormwater Credits for Better Site Design

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13.5 Overview of Structural BMP Types
Basic Structural BMP Types
13.6 Selection of Structural Management Measures
Introduction
General BMP Pollutant Removal Effectiveness
Structural BMP Screening
Step 1: Overall Applicability
Step 2: Specific Criteria
Step 3: Location and Permitting Considerations
13.7 Online Versus Offline Structural Controls
Introduction

Flow Regulators
13.8 Regional Versus On-Site Stormwater Management
Introduction
Advantages and Disadvantages of Regional Stormwater Controls
Advantages of Regional Stormwater Control
Disadvantages of Regional Stormwater Controls
Important Considerations for the Use of Regional Stormwater Controls
13.9 Using Structural Stormwater Controls in Series
Combined Measures
Stormwater Treatment Trains
Calculation of Pollutant Removal for Structural Controls in Series
Example Application
13.10 Routing with WQv Removed
13.11 Specific Structural BMP Design Guidance
Overview
Overall Design Approach
Extended Dry Detention Basin
Pond Sizing
Outlets
Pollutant Removal Information
General Design Criteria
Typical Required Specifications
Typical Recommended Specifications
Sizing Example
Retention Pond
Pollution Removal Efficiency
Pond Sizing
Typical Required Specifications
Typical Recommended Specifications
Typical Maintenance Standards for Extended Detention and Wet Ponds

Alum Treatment System
Design Example
Constructed Stormwater Wetlands
Stormwater Wetlands
Pollution Removal Efficiency
Wetland Design
Permitting
Typical Standard Specifications for Constructed Wetlands
Typical Required Specifications
Typical Recommended Specifications

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Operation and Maintenance Requirements
Bioretention Areas
Pollution Removal Efficiency
Design
Typical Required Specifications
Typical Recommended Specifications
Maintenance
Design Example
Sand Filtration Systems
Overview
Configurations
Maintenance
Austin First-Flush Filtration Basin
Pollution Removal Efficiency
Design
Operation and Maintenance Requirements

Surface Sand Filter
Design Information
Design Example
Linear (Perimeter) Sand Filter
Underground Sand Filter
Organic Sand Filters
Infiltration Trenches
Infiltration Trench Design
Typical Operation and Maintenance Requirements
Typical Required Specifications
Typical Recommended Specifications
Design Example
Porous Pavement
Pollutant Removal Efficiency
Porous Pavement Design
Operation and Maintenance Requirements
Typical Required Specifications
Typical Recommended Specifications
Design Example
Modular Paving Blocks
Typical Design Specifications for Modular Blocks
Grassed Swales
Pollutant-Removal Efficiency
Dry Swale Design
Wet Swale
Grass Channels
Typical Required Specifications: Dry and Wet Swales
Typical Recommended Specifications: Dry and Wet Swales
Typical Operation and Maintenance Procedures
Filter Strips And Flow Spreaders

Pollutant-Removal Efficiency
Design of Filter Strips
Filter without Berm
Filter Strips with Berm
Filter Strips for Pretreatment

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Typical Required Specifications
Typical Recommended Specifications
Typical Operation and Maintenance Requirements
Design Example
Oil/Grit Separators (Water-Quality Inlet, Gravity Separator)
Pollution-Removal Efficiency
Oil/Water Separator Design
Typical Required Specifications
Recommended Specifications
Operation and Maintenance Requirements
Alum Treatment
Pollutant-Removal Efficiency
Design Criteria
Proprietary Structural Controls
Local Acceptance
Multichambered Treatment Train
References

14

Stormwater Master Planning


14.1 The Role of Stormwater Master Planning
Introduction
Basic Master Plan Types
Keys to Successful Master Planning
14.2 The Master Planning Process: The Scoping Study
Step 1 — Make a Needs Analysis
Step 2 — Determine Constraints to Possible Solutions
Step 3 — Formulate the Technical Approach
The End Product of the Scoping Study
14.3 Computer Model Choice for Master Planning
14.4 Five Basic Types of Master Plans: The Flood Study
Major Creek Flooding
Data Collection
Preliminary Field Investigation
Design Storm Development
Hydrologic Model Development
Hydraulic Model Development
System Alternatives Development and Analysis
Minor System Flooding
14.5 Five Basic Types of Master Plans: The Cost/Benefit Analysis Master Plan
14.6 Five Basic Types of Master Plans: Stormwater Quality Master Plan
14.7 Five Basic Types of Master Plans: The Ecological Study Master Plan
14.8 Five Basic Types of Master Plans: The Holistic Master Plan
Introduction
Basic Approach
Example: Rapid Watershed Planning
Step 1 — Identify Initial Goals and Establish a Baseline
Step 2 — Set Up a Watershed Management Structure
Step 3 — Determine Budgetary Resources Available for Planning

Step 4 — Project Future Land-Use Change in the Watershed
and Its Subwatersheds

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Step 5 — Fine-Tune Goals for the Watershed and Its Subwatersheds
Step 6 — Develop Watershed and Subwatershed Plans
Step 7 — Adopt and Implement the Plan
Step 8 — Revisit and Update the Plan
References

15

Stormwater Quality Management Programs

15.1 Basic Urban Runoff Quality Understanding
Introduction
The Stormwater Quality Approach — History
15.2 Basic Findings
Broad Pollution Categories
Impacts of Urban Development
Changes to Stream Flow
Changes to Stream Geometry
Water-Quality Impacts
Degradation of Aquatic Habitat
Constant EMC
Source Control
Hot Spots
First Flush and Treatment Volume

Treatment Train Concept
Water-Quality Standards
15.3 Water Quality Act Overview
Phase I Basic Requirements
Municipal Reaction
Phase II Basic Requirements
Maximum Extent Practicable
Measurable Goals
15.4 The Six Minimum Controls
General Permit Conditions
The Six Minimum Controls
Guidelines for Developing and Implementing this Measure
Forming Partnerships
Using Educational Materials and Strategies
Reaching Diverse Audiences
Guidelines for Developing and Implementing this Measure
Guidelines for Developing and Implementing this Measure
Guidelines for Developing and Implementing this Measure
Guidelines for Developing and Implementing this Measure
Guidelines for Developing and Implementing this Measure
15.5 Costs of NPDES Phase II
15.6 The Ten Commandments in Developing a SWQMP
Overall Approach
The Ten Commandments
#1 — Think Paradigm Shift
#2 — Fix Real Things
#3 — Bring Me in Early, I’m Your Partner; Bring Me in Late,
I’m Your Judge
#4 — Do not Build New Problems


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#5 — Get the Foundations Right
#6 — Integrate and Graduate
#7 — Ride the Treatment Train
#8 — Get a Tool Set
#9 — Not All that Glitters is Gold
#10 — Check the Pool
15.7 The SWQMP Development Process
The Nine-Step Planning Approach
Step 1
Step 2
Step 3
Step 4
Step 5
Step 6
Evaluation of Best Management Practices
Step 7
Step 8
Step 9
EPA’s Guidance Approach
Self-Analysis
Action Plan
References

16

Site Design and Construction


16.1 Introduction
16.2 Site Design Concepts — Overview
Conservation of Natural Features and Resources
Lower-Impact Site Design Techniques
Reduction of Impervious Cover
Using Natural Features for Stormwater Management
Site-Planning Goals
Watershed Basis
16.3 Site Design Concepts — Implementation
16.4 Site Design Concepts — Design Steps
Feasibility Study
Overview
Program Components
Site Characteristics
Planning and Regulatory Controls
Site Analysis
Overview
The Concept Plan
Overview
Development of the Stormwater Concept
Preliminary/Final Plan
Overview
Preliminary Plan
Calculation of Final Stormwater Control Volumes
Final Design
Construction

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