Developing Successful Runoff Control Programs for Urbanized Areas
in
Prepared by:
Northern Virginia Soil and Water Conservation District
Fairfax, Virginia
fulfillment of Grant # X-820828-01-0/1/2 from the Nonpoint Source Control
Branch, Office of Water, U.S. Environmental Protection Agency
Final Report
July 1, 1994
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS u j
EXECUTIVE SUMMARY l
DEFINING THE PROBLEM OF URBAN RUNOFF MANAGEMENT , - 4
Introduction
Purpose and Intended Audience of this Manual 4
Brief History of Runoff Control 5
How Urban Runoff Adversely Affects Water Resources . /
The Need for Urban Runoff Management 7
Retrofitting Developed Areas J«
Local Governments' Compliance with Federal and State Regulations 11
Summary of Selected Federal Water Quality Programs 12
BRIEF SURVEY OF CURRENT METHODS AND TECHNIQUES 14
Types of Urban Runoff Retrofit Techniques - - 14
Nonstructural Methods to Control Urban Runoff 15
Structural Runoff Controls for Highly Urbanized Areas 16
DEVELOPMENT & IMPLEMENTATION OF AN URBAN RUNOFF
CONTROL PROGRAM 19
Important Program Elements 19
Building a Strong Institutional Foundation - -1
Assessing Institutional Resources 23
Setting Priorities/Selecting Management Practices 25
How To Overcome Roadblocks to Implementation 26
Funding Options/Alternative Funding Approaches : - 31.
Elements of Successful Programs/Solutions 34
Conclusions and Recommendations 34
INTRODUCTION TO THE CASE STUDIES 3?
City of Alexandria, Virginia 3°
Southeastern Massachusetts 42
City of Austin, Texas 5^
City of Orlando, Florida r3
County of Fairfax, Virginia
Cities of Eugene and Portland, Oregon 76
GLOSSARY 90
BIBLIOGRAPHY 92
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ACKNOWLEDGEMENTS
ict (NVSWCD),
This report was researched and written by Robert losco,
Specialist, Northern Virginia Soil and Water Conservation
Fairfax, Virginia.
The author would particularly like to acknowledge the contributions of Jean R.
P^karrVicTchaiLan and Director, NVSWCD, and Norman T. Jeffries, former
Executive Director, NVSWCD. They reviewed many drafts and provided valuable
Sights. In addition, the entire NVSWCD staff deserves thanks for providing the
overall assistance necessary to complete this project.
The project was funded by Grant # X-820828-01-0/1/2 from the Nonpoint Source
Control Branch, Office of Water, U.S. Environmental. Protection Agency Washington,
DC The EPA Project Officer for this grant was Rod Frederick, Chief, Urban Sources
Section, Nonpoint Source Control Branch.
The following individuals provided review comments:
Earl Shaver
Delaware Department of Natural Resources
Dover, DE
Warren Bell
City Engineer
City of Alexandria, VA
Leslie Tull
Environmental Officer
City of Austin, TX
Kevin McCann
Storm Water Utility Bureau
City of Orlando, FL
Dave Janik & Bernadette Taber
Buzzards Bay Project
Marion, MA
Noel Kaplan
Office of Comprehensive Planning
Fairfax County, VA
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Jack White
Department of Environmental Management
Fairfax County, VA
William Henry
Department of Public Works
Fairfax County, VA
Deborah Evans
Department of Public Works
City of Eugene, OR
Tom Liptan
Bureau of Environmental Services
City of Portland, OR
Dale Lehman
Woodward-Clyde Consultants
Gaithersburg, MD
William Tate
U.S. Environmental Protection Agency
Washington, DC
Robert Goo
U.S. Environmental Protection Agency
Washington, DC
Dov Weitman
U.S. Environmental Protection. Agency
Washington, DC
111
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Executive Summary
This manual defines the institutional and programmatic issues which are crucial to
the success of runoff control programs in already urbanized or urbanizing areas.
These nontechnical factors are often decisive in determining the effectiveness and
success of such programs.
The manual describes strategies which local communities can use to develop the
institutional frameworks needed to implement runoff control programs. The
strategies are described in the program development section of the manual and in the
case studies presented.
Each community will have different urban runoff management needs, environmental
concerns and available resources. Yet, building an effective program requires certain
common key steps. This manual lays out the essential elements, which will also be
useful in preparing the management plans required by various Federal regulations
and programs. In addition, retrofitting for runoff control may be necessary in some
urban areas to achieve the water quality improvements necessary under current
Federal and state mandates.
The Coastal Zone Act Reauthorization Amendments of 1990 (CZARA), §6217,
required the development of the Guidance Specifying Management Measures for
Sources of Nonpoint Pollution in Coastal Waters (USEPA, 1993). States with coastal
zone management programs are required to develop coastal nonpoint pollution
control programs consistent with these Management Measures. The "Existing
Development Management Measure" of Chapter Four (Urban Areas) requires
development and implementation of programs to reduce pollution from existing
development.
The National Pollutant Discharge Elimination System (NPDES) Storm Water Permit
Program, established by §402(p) of the Clean Water Act, requires permits for certain
municipal and industrial storm water discharges. In addition, this program requires
the development of storm water management plans for the areas covered by the
permit, which usually includes urbanized areas.
Both of these programs could involve the use of retrofits to achieve water quality
improvements. While program requirements may differ based on the specific
regulatory authority, the goals of these programs are complementary and many of
the same management practices are applicable and satisfy the requirements of both
programs. The case studies presented in this manual provide examples of the
innovative ways in which many local governments are meeting the requirements of
multiple programs to improve water quality. However, communities need to refer to
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applicable state and Federal regulations to assure that they are in compliance with all
regulatory requirements.
The manual describes ways that local governments can approach the issues
surrounding the implementation of urban runoff retrofit technology even when the
control options are limited. It reviews appropriate "ultra-urban" technologies for
situations where more conventional, land-intensive control practices are not feasible.
Specific recommendations are summarized to help program implementation
personnel develop strong institutional frameworks and create effective urban runoff
control programs. The recommendations presented are largely based on the program
implementation experiences of the case study communities featured in the manual.
They include:
Problem Identification
Identify problems clearly at the outset
Define runoff control program objectives, requirements, and penalties
Priority & Goal Setting
Consider innovative and cost effective retrofit methods
« Prioritize retrofit alternatives and set realistic goals to implement
Adequate Funding
Identify stable and/or dedicated funding sources for urban runoff
management programs
Utilize cost-share approaches among agencies
Utilize economic incentives to reduce amounts of stormwater
discharges, e.g., utility fee reductions for reduced amounts of
impervious surface
Identify opportunities for public/private partnerships to conduct
nonpoint source pollution control activities
Obtain participation and support from private interests who will benefit
from urban runoff control programs
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Multilateral Approaches
Use teams or multi-agency work groups wherever possible
Create effective institutional structures
Identify related Federal state and local programs and assess their storm
water control effectiveness and degree of interaction
Designate a lead agency to coordinate program development and
implementation
Designate sufficient agency staff to support implementation projects
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DEFINING THE PROBLEM OF URBAN RUNOFF MANAGEMENT
Introduction
This manual recommends strategies for communities to use to develop the
institutional frameworks necessary for the successful implementation of urban runoff
control projects/ including retrofit projects in developed areas. It provides practical
information for local government personnel who wish to develop such programs.
While each community will have different runoff management needs and available
resources, building an effective program requires certain common steps. This manual
describes the step-by-step procedures necessary to develop effective programs to
reduce nonpoint source pollution from urban runoff in developed areas.
Institutional factors have a significant impact on the effectiveness of urban runoff
control programs. Because the development of institutional frameworks is vital to
effective program implementation, this manual emphasizes program development,
rather than specifying technical requirements for programs. (Technical manuals for
the implementation of urban runoff controls are listed in the Bibliography.) It
recommends strategies and outlines the step-by-step procedures which are necessary
to develop urban nonpoint source pollution control programs.
Finally, in the accompanying case studies, this manual describes some approaches
which local governments have successfully used to implement urban runoff control
programs.
Purpose and Intended Audience of this Manual
This manual provides specific guidance to help local governments implement urban
runoff programs. It does not track all regulatory requirements; these will differ by
state and locality. Rather, it addresses certain elements of urban runoff control
programs that are often problematic for municipalities considering program
implemention. It is designed to help them through the program development and
implementation process.
A local government wishing to develop an urban runoff control program for
developed areas needs to base its approach on local conditions. This manual
describes the basic issues in sufficient depth, with the use of examples, to enable a
local government to design an effective program based on its particular needs.
The audience for this manual includes public agencies such as local environmental
regulatory agencies; regional and local planning agencies; councils of governments;
planning commissions, departments of public works, soil and water conservation
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districts, and other agencies concerned with land use, development, and urban runotf
management.
However, the general public also needs to be included along with interested
environmental groups and elected officials as part of the process of managing urban
runoff problems and issues; this manual seeks to impart a basic level of knowledge
about these issues to the nonprofessional or nontechnical person.
The purpose of the case studies is to present alternatives for local governments to
consider in formulating solutions to urban runoff problems. They have been chosen
to provide examples of innovative and successful alternatives in the field.
Brief History of Runoff Control
Urban runoff has not always been recognized as a major contributor of pollutants.
Historically, urban nonpoint source pollution has been overlooked by surface water-
regulation agencies at the local, state and federal levels. Efforts to control surface
water quality degradation concentrated on point sources. Urban nonpoint source
pollution control focused on street sweeping, used motor oil recycling, and public
education.1 In addition, local governments have historically been concerned mostly
with urban runoff quantity control. Water quality concerns have now become
equally important for municipalities because of federal and state mandates.
During the first fifteen years of the national program to abate and control water
pollution, EPA and the states have focused most of their water pollution control
activities on so-called "point sources," such as discharges through pipes from sewage
treatment plants and industrial facilities. These point sources have been regulated by
EPA and the states through the National Pollutant Discharge Elimination System
(NPDES) permit program established by Section 402 of the Clean Water Act.
Congress also amended the Clean Water Act in 1987 to require EPA to establish
phased NPDES requirements for storm water discharges. Storm water discharge
permits will provide a mechanism for monitoring the discharge of pollutants to
waters of the United States and for establishing appropriate controls.2
The attempts to control point source pollution have reduced pollutant loads and
Murray, James, "Nonpoint Pollution: First Step in Control,"
in Design of Urban Runoff Quality Controls, Roesner et al, eds.
American Society of Civil Engineers (New York, 1989), p. 378.
2USEPA, "Overview of the Storm Water Program," Office-of
Wastewater Enforcement and Compliance, Permits Division.
Washington, DC: March, 1993.
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considerable progress has been made in restoring and maintaining water quality.
However, the abatement of point source pollution did not solve all water quality
problems. Recent studies and surveys by EPA and by state water quality agencies
indicate that the majority of the remaining water quality impairments in our nation's
rivers, streams, lakes, estuaries, coastal waters, and wetlands result from nonpoint
source pollution and other nontraditional sources, such as urban storm water
discharges and combined sewer overflows.
Congress amended the Clean Water Act in 1987 to focus greater national efforts on
controlling nonpoint sources. Section 319 of the Act was enacted to establish a
national program to control nonpoint sources of water pollution. In addition,
Congress enacted Section 6217 of the Coastal Zone Act Reauthorization Amendments
(CZARA) in 1990 to address the impact of nonpoint source pollution on coastal
waters.
In recent years EPA introduced the Watershed Protection Approach (WPA) as a
flexible framework for focusing and integrating current efforts and exploring
innovative methods for achieving environmental objectives. The WPA focuses on
four major elements: 1) identifying specific geographic locations; 2) integrating
available authorities to deal with all pollution sources; 3) involving all stakeholders in
analyzing and creating solutions; and 4) measuring effectiveness against clearly
established objectives. These key elements are derived from experience gained over
the past few years in many states and other EPA efforts such as the Clean Lakes and
National Estuaries Programs.
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How Urban Runoff Adversely Affects Water Resources
Urbanized areas and areas in which
development has altered the natural
hydrology and infiltration characteristics
of the land typically experience
increased surface runoff. Land
development alters the natural balance
between runoff and natural absorption
areas by replacing them with greater
amounts of impervious surface. The
result is increased rates and volumes of
surface runoff.
The negative impacts of urbanization on
water quality has been well-documented
in a number of sources, including the
Nationwide Urban Runoff Program
(NURP) and the States' reports written
in response to the requirements of §305(b) and §319 of the Clean Water Act. For
example, the States report that urban runoff and storm sewers are the second leading
source of water quality impairment of lakes and estuaries, and the third leading
source of water quality impairment of rivers in the United States.
As a consequence of. the increased quantity and rate of runoff, greater amounts of
pollutants are carried into receiving waters, and water quality degradation increases.
Other negative impacts include the increased susceptibility of eroded land to
flooding, other hydrologic changes, and wildlife and in-stream habitat degradation.
[See Box 1]
The Need for Urban Runoff Management
Many American cities contain areas in which buildings, parking facilities and urban
streets and walkways cover almost one hundred percent of the land surface. This
creates runoff conditions but offers no room for structural urban runoff quality
management facilities such as extended dry detention or wet ponds. Even when
redevelopment occurs within these areas, high land values usually require
replacement by similarly intense land uses in order to provide economic viability for
the project. Conventional best management practices (BMPs) are difficult, if not
3USEPA, The Quality of Our Nation's Water: 1992, Office of
Water, EPA Document 841-S-94-002, March 1994, p. 10.
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impossible, to implement in this context.
In such situations, innovative BMP applications requiring little or no above ground
coverage are necessary in order to meet increasingly stringent Federal and state
urban runoff pollution control requirements. In highly urbanized areas, the use of
innovative urban quality control retrofitting is the primary option to improve the
water quality of surface waters which receive runoff discharges from older urbanized
areas.
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Why worry about urban runoff?
What is the problem with urban runoff anvwav?
Storm water runoff picks up pollutants and debris as it traverses developed
areas, particularly parking lots and streets. During storm events, pollutants are
picked up and flushed directly into local lakes, creeks, and streams, without
being filtered by the soil or natural vegetative cover. This endangers water
quality. Better pollution control is needed to reduce the amount of
contamination affecting these water bodies.
Isn't new development the cause of all these problems?
New development, in many localities, has to meet strict regulations on the
quality and quantity of storm water runoff. However, many of our current
water quality problems are caused by runoff from older, developed areas. We
can't solve the problem without retrofitting older stormwater control devices
or installing them where none currently exist.
How can we solve this problem?
As the public becomes aware that there are problems with urban runoff
quality, and begins to take action, the water quality of area streams and rivers
should improve. As people learn that the storm drain at the end of the street
flows straight to a nearby stream, they will be more interested in what drains
to, or is dumped in, the street catch basin. They will also press their elected
officials to incorporate stronger stormwater treatment standards into both new
development and redevelopment projects in their community.
How urban runoff affects water resources.
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Retrofitting Developed Areas
As urbanization occurs, and areas of
impervious surface increase,
maintenance of water quality becomes
increasingly difficult. Retrofit of
structural controls is often the only
feasible alternative for improving water
quality in developed areas.
Ideally, as land is developed best
management practices would be
implemented to control present and
future urban runoff problems.
However, controlling pollutants in
runoff from new development alone will
not solve existing water quality
problems. Therefore, retrofitting is
necessary. It is also the primary option
for developed areas to improve urban
runoff water quality.
Impervious surfaces in developed
areas may cover 100% of the land
surface.
Retrofitting is a process that involves the modification of existing surface water
runoff control structures or surface water runoff conveyance systems which were
designed to control flooding, so they will also serve a water quality improvement
function.
Retrofitting should also be considered as an opportunity to improve existing water
quality best management practices. Existing practices may be inadequate or
performing poorly, or they may simply lack the pollutant removal capability of
newer BMP designs. The least expensive and most practicable retrofit opportunities
often involve the improvement of existing urban BMPs. BMP retrofits are a widely
used technique. The opportunity to improve existing urban BMPs at modest cost, or
to convert older dry storm water detention ponds, for example, into more efficient
wet extended detention ponds is afforded by a retrofit approach.
Factors such as the presence of existing development, or a community's financial
constraints, may limit runoff management options; targeting may be necessary to
identify priority pollutants and select the most appropriate retrofit methods. This is
particularly true in highly urbanized areas where land is limited and the use of
conventional pond systems is restricted.
In highly urbanized areas, sand filters or water quality inlets with oil grit separators
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may be appropriate for retrofits because they do not limit land usage. Sand niters,
however, may be a better alternative for treating hydrocarbon runoff from small sites
than oil grit separators because sand is a superior filtering medium. Recent research^
questions the effectiveness of oil grit separators at removing hydrocarbon pollutants.
Urban runoff retrofitting for nonpoint source pollution control includes a broad range
of different techniques which attempt to reduce the adverse impacts of urban runoff
on receiving waters. The types of retrofit techniques will differ depending upon
where they are placed in the storm drainage network.
Local Governments' Compliance with Federal and State Regulations
The current storm water management
requirements and drainage needs in
major population centers are significant.
EPA storm water permit regulations
require large (>250,000) and medium
(>100,000) size municipalities to have
storm water discharge permits for
discharges from their storm sewer
. systems under the National Pollutant
Discharge Elimination System (NPDES)
storm water permit program. Large-
and medium-size municipalities
nationwide are now applying for these
permits which will require
implementation of comprehensive storm
water management programs to control
storm water runoff.
In addition, Section 6217(g) of the Coastal Zone Act Reauthorization Amendments
(CZARA) of 1990 requires States to develop coastal nonpoint source pollution control
programs, including a management program to control runoff from existing
development. The new coastal zone requirements are only applicable, however, in
areas which are not subject to the NPDES storm water permitting regulations.
4 Schueler, Thomas R., "Hydrocarbon Hotspots in the Urban
Landscape: Can They Be Controlled?" in Watershed Protection
Techniques. Volume 1(1), February 1994, p
11
3-5.
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The increasing stringency of federal, state and local regulations are all examples of
the emphasis being placed on minimizing both point and nonpoint source pollution
from urban runoff.
Summary of Selected Federal Water Quality Programs
Coastal Zone Management Act of 1972 (CZMA)
established a program to encourage states to develop comprehensive
programs to protect and manage coastal resources
Coastal Zone Act Reauthorization Amendments of 1990 (CZARA) S6217
mandated state coastal programs to address nonpoint source pollution
affecting coastal water quality and required the development of the
Guidance Specifying Management Measures for Sources of Nonpoint
Pollution in Coastal Waters which states are to incorporate into their
coastal nonpoint source programs
National Pollutant Discharge Elimination System (NPDES) Storm Water Permit
Program
established by §402(p) of the Clean Water Act; requires permits for
certain municipal and industrial storm water discharges
Clean Water Act $319: Nonpoint Source Control Program
initiated-a national program which resulted in state nonpoint source
management programs to control nonpoint sources of water pollution
and protect groundwater
Clean Water Act 5320: National Estuary Program
focused point and nonpoint pollution control on geographically-
targeted, high priority estuarine waters; controls are selected and
implemented on a watershed basis
EPA's Watershed Protection Approach
voluntary effort to align traditional regulatory and nonregulatory
programs to support watershed protection in an integrated, holistic
manner
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While program requirements may differ
based on the specific regulatory-
authority, the goals of these programs
are complementary and many of the
same management practices are
applicable and satisfy the requirements
of multiple programs. The case studies
presented in this manual provide
examples of the innovative ways in
which many local governments are
meeting the requirements of multiple
programs. This manual will help
communities develop and implement
pro-ams to improve water quality. However, communities need to refer to
appSle strand Federal Regulations to assure that they are in compliance with all
regulatory requirements.
For example, some communities are not subject to NPDES permit requirements but
may be subject to requirements under the Coastal Zone Act Reauthonzation
Amendments of 1990 ("CZARA"), and vice versa. In addition, some states have
fd"mo^regulatory programs that may govern the management of storm water or
runoff in the absence of Federal requirements. Other communities may not be
XctTo any regulatory requirements at this time, but the public is increasingly
aware of runoff problems and their causes and some control of runoff is becoming
inevitable.
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BRIEF SURVEY OF CURRENT METHODS AND TECHNIQUES
Types of Urban Runoff Retrofit Techniques5
Retrofit techniques can be differentiated depending upon where they are placed in
the storm drainage network. Some of these are described below:
Source retrofit: Use of techniques that attenuate runoff and/or pollutant
generation before it enters a storm drain system, e.g., reducing
impervious areas, using pollution prevention practices
Open channel retrofit: These are installed within an open channel
below a storm drain outfall, e.g., an extended detention shallow marsh
pond system.
Natural channel retrofit: Depending on the size of the channel and the
area of the floodplain, a natural channel may provide several retrofit
options
Off-line retrofit: Involves the use of a flow-splitter to divert the first
flush of runoff to a lower open area for treatment; used where land is
available for off-line treatment
Existing BMP retrofit: The retrofit of an existing BMP to improve its
pollutant removal efficiency or capacity (ability to detain flow) or both.
In-line retrofit: Used where there are space constraints that prevent the
use of diversions to treatment areas.
Urban runoff retrofits involve a broad range of different techniques intended to
reduce the adverse impacts of urban runoff on receiving waters. [See Box 2] The
overall goal should be to achieve some reasonable degree of hydrologic control and
pollutant removal (in relation to cost-effectiveness) as a result of the retrofit.
Otherwise, the retrofit is not worth doing.
5 as identified in MWCOG, Watershed Restoration Source Book,
59. .
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Technical factors affect the site-specific suitability of particular retrofit technologies.
A checklist of these factors includes:
land use ;
climate
size of drainage area
soil permeability " ,
slopes
depth to water table
space requirements
type and condition of the water
resource to be protected
depth to bedrock :
pollutants to be addressed
maintenance access
Nonstructural Methods to Control Urban Runoff
Land use controls can be a cost effective means to control urban runoff. They have a
maintenance cost/multiple use advantage over structural BMPs in many cases, and
should be employed in redevelopment situations where appropriate. Furthermore,
land use controls may be necessary along with structural measures in order for a
jurisdiction to meet its water quality goals.
Strategies for implementing land use controls may include limits on impervious
surfaces, encouragement for the preservation of open space, and promotion of cluster
development The use of nonstructural and structural best management practices for
controlling urban nonpoint source pollution can also be required as a condition of
development approval.
Zoning
Zoning is a powerful tool which communities can use to control the type of
development or redevelopment allowed within their boundaries. Following are some
examples of zoning controls that can be used to protect water resources:
cluster development: constructing dwellings close together to preserve
open space
down-zoning: changing an established zone to require a lower density
conditional zoning: allowing certain activities only under specified
conditions that protect water resources
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overlay zoning: placing additional zoning requirements on an area that
is already zoned for a specific activity or use; through the use of
resource overlay zoning, high pollution activities can be controlled in
sensitive areas
open space preservation: protecting open space and buffer zones near
water bodies, e.g., greenways or riparian corridors
Structural Runoff Controls for Highly Urbanized Areas6
1. Innovative Practices
In areas where impervious materials cover almost one hundred percent of the
surface, conventional BMPs requiring large amounts of land and good soil conditions
are usually not feasible. These types of BMPs include dry ponds, wet ponds,
constructed wetlands and various sorts of infiltration devices.
On sites where standard BMPs are not feasible, one should consider the use of
unconventional or innovative BMPs sometimes known as "ultra-urban" BMPs. These
systems are designed to function by gravity flow between the components. They
include: 1) sand filtration systems; 2) underground sand filters consisting of multiple
chambers; 3) surface sand filters such as double-trench systems; and 4) peat/sand
filtration systems.
Each is briefly described below:
Sand filtration systems: The City of Austin, Texas has developed a BMP which
consists of a sedimentation and filtration basin and is appropriate for use on
redevelopment sites where topography, space limitations and high value land do not
allow the use of traditional BMPs. These filtration systems are primary water quality
control structures. In order to ensure the long-term effectiveness of these systems, it
is necessary to protect the filter media from excessive sediment loading. A sediment
trapping structure is required to be located prior to the filtration basin. Austin sand
filter sytems are particularly well-suited to regional storm water control.
Underground sand filters with multiple chambers: This is a system consisting of a
structure containing three chambers, one each for pre-treatment, filtration and
discharge. The first chamber is a pre-treatment facility performing the same function
as a water quality inlet, removing floating debris and material such as oil and grease.
6 A more detailed description of these controls and their
effectiveness is provided in the Alexandria Supplement to the
Northern Virginia BMP Handbook, [see Bibliography]
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The second chamber is a filtration device, while the third is a clear well discharging
directly to the storm sewer system. The District of Columbia uses underground sand
filters as in-line facilities for both storm water quality and peak flow attenuation.
One of the major advantages of the D.C. sand filter is that it does not take up any
space on the surface, allowing full use of high-value urban land. This aspect makes
it particularly attractive to land developers.
*»«*> «»nH filter systems: This system is usually referred to as the Delaware sand
filter because it was developed for use in Delaware. Unlike the other filters
described in this section, the surface sand filter system is intended to be an on-hne
facility, processing all runoff leaving the site up to the point where the overflow limit
s reached It consists of two parallel concrete trenches, one for sedimentation, the
Stotoffltotion. A major advantage of this filter design is that it requires a depth
o only 30 inches from the ground surface to the bottom of the paved trench, making
it useful in areas with high water tables. The simplicity of the design also facilitates
maintenance.
P^can filtration systems: Peat/sand filters are filtration
developed as alternative wastewater systems. Peat is an excellent natural filter of
many types of effluents and pollutants and is just beginning to be used for urban
mnotf quality management. A peat/sand filter system should be considered for use
TdevelopmLts of several acres where the pollutant removal requirement is higher -
San couldPbe expected to be achieved through the use of other ultra-urban BMPs. In
addition, peat/sand filters require less site area than most conventional BMPs.
" However it should be noted that, under certain conditions, peat filters can become
net exporters of nutrients.
Use of Publir Ri^hts-of-Wav
A retrofit technique which has been identified for use in a land-limited context is the
use of public rights-of-way as an opportunity for runoff controls such as wet ponds
vegetated swales or meandering vegetated channels. This would include the use of
land under bridges and overpasses, the median strips of roads and highways, and the
exit ramp rights-of-way off major highways.
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2. Retrofit Capability of Selected BMPs7
Extended Detention Ponds: Frequently used in retrofit applications, particularly
within dry storm water management ponds.
Wet Ponds: Occasionally used in retrofit situations, particularly within dry storm
water basins
Constructed Storm Water Wetlands: An effective retrofit technique. Can be achieved
by adding wetland features to dry storm water basins.
Infiltration Trenches: Limited by soil conditions.
Infiltration Basins: Not recommended for retrofit settings, especially in the coastal
zone.
Porous Pavement: Limited by soils which have been modified in most urbanized
watersheds and are not capable of providing adequate infiltration.
Sand/Peat Sand Filters: Designed as end-of-pipe retrofits in several applications. A
double-trench version has been designed for parking lot retrofits.
Grassed Swales: Although not suitable for ultra-urban areas because of the difficulty
of preventing erosion in highly impervious areas, retrofit option may involve
installing check dams to increase contact time in existing swales.
Filter Strips: Although the percentage of impervious surface in highly urbanized
areas limits the usefulness of this practice as a water quality control device in ultra-
urban settings, this type of retrofit is appropriate if enough land is available.
Water Quality Inlets: Although water-quality inlets are often used in ultra-urban
areas, their low pollutant removal capability limits their usefulness as a retrofit
technology.
" More detailed information on the retrofit capability of
these practices can be found in A Current Assessment of Urban
>Best Management Practices. [see Bibliography]
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DEVELOPMENT & IMPLEMENTATION OF AN URBAN RUNOFF CONTROL
PROGRAM
While the program elements discussed in this section are considered important to
program development and success, they do not necessarily fulfill all regulatory
requirements which may be applicable to a given municipality. Planners and
program managers should check on all relevant program requirements when
developing their programs.
Important Program Elements
An urban runoff control and retrofit implementation program involves both technical
and programmatic components and should include the following elements:
technical capability
use of appropriate technology
implementation authority/enabling legislation
funding mechanism or resource commitment
institutional support structures
The case studies which are part of this manual demonstrate that local motivation is
critical to the successful implementation of urban runoff controls. Also, successful
implementation will not occur without a strong local commitment of personnel and
resources. Regulations, ordinances, enabling legislation, design criteria, construction
specifications, inspections and enforcement, and operations and maintenance
procedures should all be clear and explicit. Appropriate technology for
implementing runoff control measures must exist and must be at an affordable cost
to the agency. If the foregoing are not present, implementation or continued
successful program performance may not occur.
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Important Elements for Program Success
Technical Capability
Design Criteria for Selection of Appropriate
Technology
Implementation Authority/Enabling Legislation
x f "*<*
Dedicated Funding Mechanism
^ Vt" < -
Staffing/Training/Institutional Support/Operations &
Maintenance
The box above depicts some of the key elements for- developing and conducting a
successful urban runoff control program. All of them may significantly affect
program outcome:
technical capability and the choice of an appropriate technical solution
implementation authority and a dedicated funding mechanism
the often-neglected elements of program staffing, proper training, strong
institutional support, and the proper operations and maintenance
procedures
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Building a Strong Institutional Foundation
Urban runoff management program practitioners strongly support the view that the
success or failure of urban runoff control programs depends upon effective
institutional frameworks. The following elements are often cited as crucial to
program success:
Programmatic:
adequate problem assessment
BMP targeting and selection methodology (e.g., on-site vs. regional
facilities)
appropriate design criteria
adequate staffing and training
responsibility for success of total program vested in a single agency at
an appropriate level of authority
Funding/Implementation:
dedicated program funding, such as a storm water utility fee
ease of operation and maintenance procedures
administrative mechanism to ensure O & M is performed
Each of these elements must receive adequate institutional support if a successful
urban runoff control program is to be implemented. In order to develop the
necessary institutional frameworks, the local government should focus sustained
attention on the institutional aspects of program development. There should be a
recognition that developing an institutional framework is essential to support a
successful multi-agency, long-term urban nonpoint source runoff program.
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How can communities develop a
successful program?
Each local government may have
mmmmmmmmmmmm^i^mm^^^^^mm^mi^m^fm different tasks to complete to create a
successful program. However, certain
common threads run through all the case studies described in this manual and these
can be instructive in helping local governments to put together effective urban runoff
control programs.
A strong motivation to act is essential.
Frequently the strongest
motivation to act is economic. In the mm^^^^^^^i^^~^~^^
Southeastern Massachusetts area case
study, the closure of thousands of acres of shellfish beds due to contamination by
storm water runoff resulted in millions of dollars of lost income to local residents and
serious disruption to local economies.
For other communities, such as Austin, TX, protection of drinking water supplies is a
high priority. Still others, such as Orlando, FL, are concerned about the water quality
of the hundreds of lakes within its metropolitan region.
Teamwork is essential to accomplish
Pick the right people and the right your goals.
organizations. The experience gained ^^__________^___^______
from the case studies proves that ^^*mam^mmfg^*m^^*m^*~m
teamwork is necessary to achieve the
desired results. The nature of the urban runoff problem means that any solution will
cut across departmental, bureaucratic and organizational boundaries. The high cost
of storm water control projects, especially retrofits, makes cost-sharing among
organizations particularly advisable. So identify the key players early and make
good working relationships a high priority. Don't neglect the important role of
private organizations and interests.
The need for adequate staffing and
training should be recognized.
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Assessing Institutional Resources
Two initial goals should be considered
by a local government interested in
developing an urban runoff control
program:
1) developing or improving
its institutional capacity to
mitigate the urban runoff
water quality problems
which it faces
2) ensuring that its institutional capacity matches its technical ability to
deal with the problem.
Implementation personnel should evaluate the following factors as part of an initial
assessment of institutional structures:
Identify the kev agencies and personnel
Determine who the key players are in the relevant agencies. Typically, there are four
major groups involved in the institutional water quality decision-making process:
1) legislative
2) regulatory
3) consulting professionals
4) "users" such as developers, clients, citizens (also includes
environmental advocacy groups)
The program manager should be aware that the typical bureaucratic organization of
institutions into branches, divisions, departments, etc., can hamper the ability of the
organization to carry out its program goals and hinder program effectiveness. The
most successful programs find ways to break the bureaucratic logjam.
Identify all relevant existing programs and assess their effectiveness
This may involve looking at an array of water quality programs scattered across
different agencies and departments. Look for opportunities to modify these
programs to reach the desired goals. Make sure that existing governmental
structures are capable of implementing proposed programs. Finally, identify- what
new programs are needed.
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Determine the motivations and goals of the key agencies
They may be acting in response to a
perceived problem such as a health
hazard or to a water use impairment.
Remember that not all organizations are
subject to the same level of political
pressure.
Determine whether
political support exists
This includes both established and grassroots structures. Political support for
environmental issues becomes especially significant in times of resource constraints
and competing interests.
Identify appropriate pollution control techniques
Consult a BMP manual, such as those listed in the Bibliography, for the types of
control mechanisms appropriate to a particular site.
Identify funding options
This might include study of the feasibility of a dedicated funding source such as a
storm water utility and development of a fee structure.
Consider the limitations of available technology
The potential for solving a problem may be limited by many factors over which the
implementing authority has no control. This includes performance limitations of
technology as well as any site-specific constraints.
Conclusion
The importance of developing institutional structures cannot be overstated. Effective
urban runoff management is greatly helped by the presence of strong institutional
mechanisms. Furthermore, the case studies support the conclusion that where urban
runoff quality control is institutionalized through dedicated funding mechanisms
such as storm water utilities, innovative and comprehensive programs (including
retrofit activity) are the rule.
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Setting Priorities/Selecting Management Practices
Urban nonpoint source runoff problems may be numerous in a given area and the
solutions are often complex. Funding to solve these problems is usually limited so it
is necessary to set priorities so that the worst problems can be targeted for attention.
A ranking methodology should be developed for a specific study area (e.g., a
watershed) in order to encourage a phased approach and to allocate scarce resources
optimally. Once particular waterbodies and sources have been targeted for action,
the local government can then determine the most cost effective approach to solve the
problem.
The following factors should be considered in the ranking process:
waterbody importance
type of use (recreation/aquatic life/drainage)
status of use (impaired or denied uses)
level of use
pollutant loads
The key point to be made about the ranking process is that it should reflect local
issues and concerns. The ranking factors can be assigned different degrees of weight
based on the degree of local importance.
In evaluating and selecting appropriate control practices, local governments should
consider:
Does the practice selected meet any applicable regulatory requirements?
Is the selected control buildable and effective?
Relying upon structural controls is different from the use of source controls and
regulatory or non-structural controls. Complex structural controls pose both
construction and future maintenance challenges that should not be overlooked.
Use the following as a checklist of the tests which the proposed BMP should pass to
be considered for implementation:
Does it meet regulatory requirements?
Is it effective at pollutant removal?
Can it gain public acceptance?
Is it technically implementable/easily maintained?
What are the associated costs?
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The process of setting priorities and targeting urban runoff problems is a complex
process consisting of many factors and should be performed in a systematic manner.
How To Overcome Roadblocks to Implementation
Two of the biggest "roadblocks" to implementation of urban runoff control retrofit
projects are high cost and shortage of funding and the lack of available land in
urbanized areas. Many participants in the urban runoff management and planning
process describe the extreme difficulty of implementing urban runoff retrofits
because of the lack of available land at highly urbanized sites and the lack of funding
for these typically expensive projects. The most difficult sites are those where land
for siting control practices is severely constrained or non-existent. The high cost
associated with retrofitting older urban storm drainage systems requires a careful
evaluation of pollutant reduction goals and the targeting of control practices.
Land Availability
In the urban context, land may be strictly limited and/or its value may be prohibitive
for some uses. Practices requiring large land areas are simply not feasible. The three
most used control devices for storm water quality management, vizv dry ponds, wet
ponds, and infiltration devices, are not always suitable for urban retrofit situations
because of space constraints or underlying soil conditions.
On sites where these types of conventional practices are not feasible, innovative and
experimental approaches should be tried. Newer ultra-urban technologies that take
up little or no above-ground space should be used. Performance monitoring should
be done to verify effectiveness.
Cost of Implementation
The extremely high cost of retrofit projects - engineering studies, land acquisition,
and the actual construction costs - raises the question of how realistic these projects
are for many local governments to achieve. In addition to initial project cost, there is
also the continuing and long-term cost associated with operations and maintenance.
Some ways to reduce the high cost of these projects include:
utilizing state or federal cost-share programs where available (e.g.
FEMA floodplain "buyout" or EPA nonpoint source grants)
* encouraging multi-jurisdictional efforts to spread the cost and benefits
soliciting volunteers and in-kind contributions to reduce project cost
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. creation of special districts or dedicated funds such as storm water
utilities
low interest state revolving fund (SRF) loans for nonpoint source control
projects
The use of high value urban land is the biggest obstacle to implementing retrofits for
many municipalities. Land which would ordinarily be generating revenue for the
municipality is removed from the tax rolls. This is a clear institutional disincentive to
implement retrofits in highly urbanized areas. If a local government considers water
quality improvement as a goal desired by the community, then the revenue loss
might be viewed differently by the public, and would be easier to justify politically.
Localities are increasingly turning to methods of returning the costs of storm water
discharges to individual property owners, through mechanisms such as storm water
utility fees or storm drainage and flood control fees. The goal of these programs is to
provide economic incentives to property owners to reduce the amount of storm water
discharges from their land by offering credits for implementation of best management
practices, as well as to reduce the burdensome cost to already fiscally-strained
jurisdictions.
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Increasing Public Awareness
To ensure adequate support for urban
runoff control programs, the public
needs to be educated about the nature
of urban nonpoint source pollution and
the benefits of controlling urban runoff.
These issues are not readily understood
by large segments of the public. The
need to heighten public awareness
cannot be overemphasized.
Urban runoff control programs must
have public backing and involvement to
succeed. There is broad general support
for environmental concerns and this
support can be translated into political
support for urban runoff control
programs. However, adequate funds must be devoted to public information and
education programs about the nature, causes and solutions of urban runoff and urban
nonpoint source pollution. The public must recognize the seriousness of urban
runoff pollution, and understand the importance of local commitment for a successful
urban runoff management or retrofit program.
Public education is an essential tool for
increasing public awareness and
generating political support.
Educational efforts typically include:
program meetings and
presentations
program materials such as
newsletters, fact sheets,
brochures, and posters
homeowner education programs
media campaigns
coordination with activist groups for program support
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Creating a Stable Funding Mechanism
Runoff control programs are usually
implemented at the local level. Local
communities generally have limited
budgets and limited staffing which
impedes effective implementation.
Sources of funding at the Federal and
state levels are also limited and
uncertain, and cannot be counted upon
to provide total project funding.
One successful institutional response by
many municipalities has been the establishment of storm water utilities. Some
jurisdictions have used storm water utilities to fund the basic "hardware" of urban
runoff management, while others have included funding for watershed planning and
retrofitting programs.
Special taxing districts, such as a watershed improvement district, can levy taxes and
borrow money to engage in a wide range of nonpoint source pollution control
activities. A special taxing district is similar to a school district or a sanitary district
and functions as a special governmental unit in a particular area. Real estate within
its boundaries is appraised and taxed to fund program activities.
The purpose of a dedicated funding source such as a storm water utility or a special
taxing district is to provide a stable and reliable method of financing storm water
management programs. The development of comprehensive and effective programs
requires a secure funding base.
[More information on funding options is provided below.]
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Policies and Procedures vs. Programs and Institutional Frameworks.
Effective prevention and control of urban runoff pollution requires both defined
policies and procedures, and effective programs and institutional structures. Just
having policies on paper is no guarantee of an effective program. Institutions must
be organized in such a way as to implement the policies and carry out the
procedures.
Indeed, the implementation phase is just the final step in an often long process of
planning and preparation. It must be accompanied by a real institutional
committment to change ineffective and outmoded structures, to break through
political or bureaucratic impasse, and to see that programs function effectively.
The question for the local program manager is: Are the local government's agencies
organized to efficiently and effectively carry out runoff control activities? Are the
various agencies involved clear about their responsibilities? Responsibilities of each
involved party can become a major issue when urban nonpoint source control
projects involve multiple agencies, as they almost always do.
The responsibility of each agency
involved in an urban runoff control
project should be clearly spelled out.
The complexity of developing and
implementing urban runoff control
programs, including the special
considerations relative to retrofit
situations, means that the following
distinct phases should be well-known to the program manager:8
planning phase: analyze, evaluate, plan
preparation phase: prepare budget, allocate resources, and obtain
permits
pilot project phase: test selected BMPs
full-scale implementation: construct selected BMPs
evaluation/documentation: evaluate program effectiveness
8 U.S. Environmental Protection Agency, "Evaluating Nonpoint
Source Control Projects in an Urban Watershed," in Nonpoint
Source Watershed Workshop. Seminar Publication tt EPA/625/4 -
,91/027.
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Funding Options/Alternative Funding Approaches
Implementation of urban runoff control programs at the local level often requires
non-Federal funding. Now that governments at all levels are facing fiscal constraints,
alternative funding sources are becoming increasingly important. Following is a
discussion of some of these approaches:
Local governments with strong
institutional frameworks have led the
way in the development of utilities
specifically designed to abate NFS =
pollution or targeted at a particular type
of NFS pollution:
Local governments are
using the utility concept to
develop institutional
approaches incorporating
homeowner responsibility
for some runoff
management practices (e.g., septic system maintenance, small
construction grading and landscaping permits requiring best
management practices to control runoff)
Storm water utilities are spreading all over the country as a way of
providing a dedicated funding source for urban runoff control projects;
a storm water utility is to storm water what a sewage utility is to
sewage and a water utility is to drinking water. It is a dedicated
funding source or "stand alone" service unit within the city government
which generates revenues through fees for service. It is responsible for
the operation, construction and maintenance of storm water
management devices and for storm water system planning.
State revolving loan funds were very successful in the early years of point source
pollution control and are now being adapted to nonpoint sources:
State revolving loan funds, originally established for states to upgrade
sewage treatment facilities through construction grants, may also be
used to fund a wide variety of nonpoint source control projects and best
management practices (BMPs)
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Special fees and taxes are another source of dedicated project funds for nonpoint
source pollution control:
This approach involves the use of user fees/special taxes to fund
nonpoint source pollution projects and programs, such as special taxes
and fees on the sale of fertilizers and pesticides, waste disposal, and
underground storage tanks
Some innovative approaches being used to fund urban nonpoint source pollution
control programs include: :
Special tax districts, such as watershed improvement districts, which can
be created to protect highly valued water bodies.
Checkoff on tax forms to fund restoration and conservation programs.
Revenue bonds, which are long-term municipal bonds guaranteed solely
by the dedication of project funds.
Public/private partnerships can be used to pay for capital and/or
operating expenses, for storm water facility projects when neither could
fund them alone.
An annual nonpoint source pollution control tax based on property size
and land use (not on value) is being used in Puget Sound, Washington.
The sale of special license plates in Maryland and Virginia has raised
substantial amounts of money to restore the Chesapeake Bay.
Types of Funding Mechanisms Available to Local Governments
General funds
The use of general funds may require the re-allocation of existing
revenues.
Long-term borrowing
Large structural BMPs may require funding through bond issues.
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Pro-rata share fees
These fees are typically based on an assessment of the development's
potential to contribute to urban runoff problems.
Storm water utilities
Utilities typically assess a fee based on the percentage of a site's
impervious area.
Special assessment districts
Funds for projects in a district can be raised by assessing fees to
landowners in the district.
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Elements of Successful Programs/Solutions
The case studies presented in this
manual were selected as examples of
exemplary local government initiatives
in the area of urban runoff control
and/or retrofit implementation. The
case studies included are all "success
stories," and they display certain
common elements. Among these are the
following:
strong institutional motivation to act on problem
political and/or grassroots support for action
skilled personnel
knowledge of available technologies
dedicated funding source, such as a storm water utility fee
an environment of institutional cooperation and a long-term
commitment to work together
targeting strategy/process to maximize use of limited resources
Many communities are recognizing the benefit of preventing ecological and habitat
destruction to avoid the very high costs associated with the restoration of degraded
resources. The most successful communities take a pro-active stance with regard to
regulatory requirements, and use proper planning techniques to prevent degradation
of water resources. They are realizing the economic, environmental and social
benefits of protecting the existing ecosystem through land use controls, development
restrictions and urban'best management practices.
Conclusions and Recommendations
Effective urban runoff control programs are built upon numerous institutional,
economic and technical factors. The most successful programs examined in this
project displayed a strong institutional or programmatic focus, in additional to having
a strong motivation (usually economic) to act on a problem. Furthermore, the case
study communities displayed strong political and/or grassroots support for
community action as well as skilled personnel.
Solutions must be tailored to each communities' particular circumstances, but the
following recommendations may assist the interested community to more quickly
develop an urban runoff control or retrofit program for developed areas.
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Recommendations
Identify and obtain stable, if not dedicated, funding sources for urban
runoff programs, including retrofit programs.
Utilize cost-share approaches among agencies to maximize resource
impact and obtain participation and support from private interests
benefitting from urban runoff control projects.
Use team or multilateral approaches wherever possible; given the nature
of urban runoff problems, most solutions will need to cut across
bureaucratic and organizational boundaries.
Focus effort initially on building institutional structures to support
comprehensive urban runoff control programs.
Identify water quality problems and prioritize retrofit alternatives.
Identify all existing related programs and assess their effectiveness and
modify where needed.
Consider innovative, cost effective, and environmentally responsible
ways of retrofitting.
Utilize economic incentives (such as tax or fee reductions) to motivate
property owners to employ runoff control and/or retrofit strategies.
Make retrofit projects a condition of approval for redevelopment
projects.
Create a single management agency charged with overall responsibility
to plan and coordinate program implementation and conduct and/or
monitor operations and maintenance activities.
Designate agency staff to support implementation of projects.
Do adequate retrofit planning and realistic goal setting.
Select knowledgeable contractors or contractors with a good track record
in water quality and urban runoff control projects.
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Supervise, even direct if necessary, the construction phase of ail projects.
Educate developers, consultants, contractors, politicians and the general
public about urban nonpoint source pollutions issues.
Identify opportunities for public/private partnerships to conduct
nonpoint source pollution control activities.
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Introduction to the Case Studies
The following case studies exemplify many of the institutional, regulatory, planning
and implementation issues discussed throughout this manual. They describe the
experiences of selected local governments in dealing with the problem of urban
runoff management in developed areas. Many of the approaches described in the
case studies are highly innovative and will be useful guides for other localities
considering the implementation of urban runoff control and/or retrofit programs.
This manual utilizes the case studies to illustrate some approaches which localities
are successfully using to manage urban runoff problems. It provides examples of
jurisdictions where institutional frameworks have been successfully developed to
support urban runoff management and retrofit programs. Institutional issues are
given great emphasis in the case studies, as in the main narrative, because
institutional issues, rather than purely technical ones, are believed to be a common
obstacle to the successful implementation of urban runoff management projects.
The case studies demonstrate the many different ways communities have developed
and implemented urban runoff management programs. Each program is unique,
based on the magnitude and negative impact of that community's urban runoff
problem, the available resources and existing pollution control programs, and the
existing regulatory context in which the local government is operating.
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Citv of Alexandria, Virginia
Introduction
Municipalities are being confronted by increasingly stringent local, state, and Federal
environmental regulations. Complying with these regulations is a challenge. The
approach taken by the City of Alexandria, Virginia is a case study which illustrates
this point.
Alexandria is situated on the tidal Potomac River, across and down river from
Washington, DC. Because of its location, the City must comply with Virginia's
"Chesapeake Bay Preservation Act." The Act's implementing regulations required the
City to designate "Chesapeake Bay Preservation Areas" within its boundaries. The
City as a whole was designated to be a preservation area. This designation means
that development and redevelopment of land in the City must achieve specified
storm water management criteria. For permitted development, nonpoint source
pollution loads cannot exceed pre-development loads based on average land cover
conditions. For redevelopment of land currently served by water quality best
management practices (BMPs), nonpoint source pollution in post-development runoff
cannot exceed the load existing prior to redevelopment. For redevelopment of land
not currently served by water quality BMPs, a ten percent reduction in nonpoint
source pollution in runoff must be achieved when compared to the load existing
prior to redevelopment.
Meeting these storm water management criteria in Alexandria has indeed been a
challenge. Implementing conventional water quality BMPs to control the quality of
storm water discharges is often either economically impractical or physically
impossible because of a number of factors such as a lack of physical space, extremely
high land values, a high water table, or unsuitable soil conditions. The City has met
the challenge by adopting and adapting for local use a class of BMPs dubbed "ultra-
urban."
Ultra-urban BMPs are non-conventional BMPs that are particularly suited for use in
highly urbanized areas. They are based on sand filter technology and are currently
used "in other parts of the United States. Alexandria has installed four of these ultra-
urban BMPs in intensely developed areas. In order to facilitate the use of sand filter
technology, the City has published design criteria for various ultra-urban BMPs in the
Alexandria Supplement to the Northern Virginia BMP Handbook.
The Alexandria Supplement states that the standard types of BMP facilities such as
dry ponds, wet ponds, and infiltration devices are not suitable for use in large areas
of Alexandria because of space limitations or poor soil conditions. The planner,
developer, or engineer is therefore urged to consider the use of unconventional or
38
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innovative BMPs. It should be noted that infiltration is not the preferred method in
Alexandria and will only be approved where it can be clearly demonstrated that it }
will work Most areas of Alexandria do not contain soils that are conducive to the
use of infiltration devices. (Marine clay is the prevalent soil type in Alexandria and
the region.)
To complicate the problem, Alexandria, in common with many older cities developed
in previous centuries, has sections of combined sanitary and storm sewers. During
heavy or prolonged storm events, combined sewer overflows (CSOs) may occur,
discharging directly into streams. Alexandria has applied for an NPDES permit for
the CSOs from the Virginia Department of Environmental Quality.
Strategy
The development of design criteria to guide local developers, culminating in the
Alexandria Supplement to the Northern Virginia BMP Handbook, resulted from the
City's engineering staff consulting with jurisdictions across the country where similar
ultra-urban technology is being proposed or has been implemented.
It should be noted that the City's strategy of implementing ultra-urban BMPs was
essentially driven by the lack of available land and alternatives. Most other BVPs
were fairly easily screened out because of the severe space constraints. Available
technology aside, the other principal strategy issue requires that opportunities be
seized as they arise, usually from redevelopment.
The general strategy employed in the implementation of these retrofits was one of
exploiting any available opportunities. Cooperation was solicited from developers.
The double trench Delaware sand filters which were implemented did not take up
any valuable land above-ground and this was a strong selling point for bottom-line
conscious developers. This allowed them full economic use of the land. The focus
has been on available sites. Parking lots have been the chief sites suitable for the
Delaware sand filters, and implementation has been limited to them.
One advantage of the Delaware sand filter for Alexandria is that it requires a total
depth of 30 inches from the ground surface to the bottom of the paved trench. This
is critical in portions of the city where the depth to groundwater is minimal. In
addition, the simplicity of the system and the ready accessibility of the chambers for
regular maintenance makes the Delaware-type filter very suitable for site conditions
which are typical in Alexandria. This type of system is appropriate for up to five
acres of 100% impervious cover.
Two [District of Columbia] underground vault sand filter systems were installed on a
3-acre townhouse development in the Winter/Spring of 1994. The principal
advantage of these systems is that they may be placed under streets, and in cells of
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parking garages, allowing full economic use of the surface areas.
The cost of implementing sand filter technology varies due to site-specific conditions.
Most of the devices already implemented in Alexandria were prototypes, making
accurate cost estimates difficult. However, a range based on the characteristic design
of the Delaware, Austin, and District of Columbia designs can be estimated. The
costs of Austin sand filters, typically suitable for large-scale sites, range from $13,000
to $19,000 per impervious acre. The D.C. sand filter, which is characterized by an
underground vault with sediment and filtration chambers, originally cost around
$35,000 per unit, but through economies such as pre-cast concrete and standardized
design, costs have come down considerably to the $12,000 to $16,000 range. It should
be borne in mind that the early models of these systems are essentially prototypes
and that costs are highly variable. Economies of scale are likely to come about
through routine implementation. The use of prefabrication and modular units may
further reduce costs in the future.9
Effectiveness of Ultra-Urban BMPs compared with Conventional BMPs
Most of the (Delaware) double-trench sand filters implemented to date in Alexandria
have not been subjected to long-term monitoring and Delaware does not rate these
systems for nutrient removal efficiency. Based on long-term monitoring of sand
filtration systems done by Austin, Texas, the Delaware system is rated at 80%
suspended solids removal rate. Alexandria, however, recognizes a TP (total
phosphorus) removal rate of 40%.10
The Virginia Chesapeake Bay Local Assistance Department has provided a grant to
the City of Alexandria to monitor the performance of the first two Delaware sand
filters constructed in the city.
Other Institutional Issues
This case study illustrates the benefit of having a committed public official dedicated
to implementation of nonpoint source pollution control technology. The City
Engineer has implemented retrofits mostly on his own initiative, having had
relatively few bureaucratic obstacles to overcome.
9 Warren Bell, A Catalog of Stormvater Quality Best
Management Practices for Ultra-Urban Watersheds. Presented at
the National Conference on Urban Runoff Management in Chicago,
on April 2, 1993.
IL
10 Ibid.
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There are other programs described in case studies in this manual where institutional
support comes from the "grass roots." It is vital to have public support for pollution
control programs, but building support for these programs may sometimes require
that public officials take the lead and steer programs past the numerous bureaucratic
obstacles.
For more information...
For more information on the City of Alexandria's program, call the Transportation
and Environmental Services Department at (703) 838-4320.
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Southeastern Massachusetts
This case study looks at storm water retrofit projects in the following areas of Cape
Cod:
Buzzards Bay/Buttermilk Bay:
1) Spragues Cove Storm Water Remediation Project (Town of
Marion)
2) Broad Marsh River Storm Water Remediation Project (Town of
Wareham)
3) Electric Avenue Beach Storm Water Demonstration Project (Town
of Bourne)
4) Hen Cove NFS Pollution Mitigation Project (Town of Bourne)
Town of Yarmouth
Town of Orleans
Existing Nonpoint Pollution Problems on Cape Cod
A Cape Cod Section 208 planning study identified the following pollutants in storm
water runoff from urban sources at various locations on the Cape:
Organics: Oil and grease (hydrocarbons), benzene, xylene, and toluene
from auto emissions or atmospheric deposition. Runoff from roads into
Buzzards Bay is estimated to contribute 33,000 Ibs. of petroleum
hydrocarbons a year to the Bay.
Inorganics: Nitrates, phosphates, ammonia, chloride, sodium, calcium,
potassium, barium, iron, cadmium, chromium, copper, lead, and zinc
have all been identified in runoff from a section of Route 28 near
Falmouth.
Biological: Bacteriological contaminants (mostly fecal coliform) in storm water
runoff were strongly implicated in the closure of shellfish beds in Buttermilk
Bay (Bourne).
I. Case Studies
Buzzards Bay Area
In Buzzards Bay, over 8,000 acres of shellfish beds are believed to be closed as a
i
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direct result of storm water contamination. This represents an estimated economic
loss of $24 million to communities in the Buzzards Bay area.11 The Buzzards Bay
Comprehensive Conservation Management Plan (CCMP) adopted in 1992 calls for the
prevention of new storm water discharges to the Bay, as well as the remediation of
existing discharges that pose a threat to water resources. The plan also calls for
towns to inventory and prioritize storm water discharges for remediation. After
towns have evaluated their storm water needs, they can proceed based on available
resources Funding, however, is one of the most significant factors affecting the
ability of Southeastern Massachusetts area towns to deal with their urban runoff
problems.
The development of the Buzzards Bay CCMP resulted in some significant
accomplishments for the Buzzards Bay region:
it established overlay district protection to limit nitrogen inputs to
marine waters of Buttermilk Bay (a first in the nation)
it resulted in the development of regional strategies, approaches and
enforceable mechanisms as part of the Massachusetts Coastal Zone
Management program
1. Electric Avenue Beach
Strategy and Rationale
An existing storm water system was retrofitted at Electric Avenue Beach in Bourne,
Massachusetts as a demonstration project as part of the Buzzards Bay Project (a joint
project of the Massachusetts Coastal Zone Management Program and the U.S.
Environmental Protection Agency). The project was undertaken in response to high
fecal coliform bacteria levels found in wet weather storm drain discharges to
Buttermilk Bay, a tidal embayment in the towns of Bourne and Wareham at the
northern end of Buzzards Bay. The Buzzards Bay Project funded the implementation
of a storm water infiltration system in order to test the effectiveness of these systems
in removing bacterial and nutrient contamination from the storm water runoff
entering Buttermilk Bay.
The storm water infiltration system was designed to intercept a one-year design
storrn from the adjacent watershed and to avoid direct discharge of the first flush to
the Bay. Instead, the flow enters a settling tank for removal of solids and floatable
waste and is then discharged to infiltration galleys. The only flow which is
11 Buzzards Bay Project, "Bay Watch," (Newsletter)
Spring/Summer 1993 Vol. 7 (5), p. 1.
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discharged from the original outfall is from a one-year storm or better. Monitoring
provided by the Barnstable County Health Department has confirmed a reduction in
bacterial loading.
There are other points which make this project noteworthy:
the infiltration galleys are preceded by oil/grit chambers designed to
reduce clogging in the infiltration devices
because the infiltration devices are very dose to the beach area, the
distance to groundwater is approximately two feet - groundwater
sampling has not shown any contamination, however
a substantial reduction in construction costs was achieved by utilizing
personnel from the Town of Bourne's Department of Public Works
One of the unique aspects of this demonstration project was that the EPA Region I
and Buzzards Bay Project oversight staff utilized the Department of Public Works
personnel from the Town of Bourne for construction of the storm water infiltration
system. The significant institutional consideration here is that the experience gained
by Town staff in the design of the demonstration project could be used for the
construction and maintenance of additional storm water infiltration systems. This
enhances the storm water quality control expertise of Town personnel and further
institutionalizes the process.
Effectiveness
At the Electric Avenue demonstration project site in Bourne, monitoring indicates that
the retrofit structures are removing over 95% of the fecal coliform from storm water
runoff.
2. Hen Cove Monpoint Source Pollution Mitigation Project
Storm water runoff pollution was implicated in the closure of shellfish beds and a
swimming beach in Hen Cove. The Buzzards Bay Project assisted the Town of
Bourne in retrofitting the adjacent storm drain systems so that pollutants are not
discharged directly to the Cove.
Strategy and Rationale
The Hen Cove project targeted specific storm drain systems which currently allow
direct discharge of untreated storm water into the Cove. The mitigation project
incorporated the use of leaching chambers and the surrounding soil to treat the "first
flush." (During heavier or more severe storms, excessive runoff will overflow into the
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conventional storm drain system.) Several individual leaching chambers were placed
under the road surface throughout the watershed (there are 13 so far). At each
location, runoff from the road will be diverted into a storm drain with a settling I
basin to allow sediments and other solids to settle out. From the storm drain inlet,
the storm water is then piped under the road surface into leaching chambers. The
leaching chambers are pre-cast, perforated concrete structures which are surrounded
by crushed stone. Storm water is temporarily stored in the chambers and in the
voids between the crushed stone until it seeps into the surrounding soils.
Groundwater monitoring will determine the success of this approach by determining
the amount and type of pollution attenuation in the surrounding soils.
3. Spragues Cove Storm Water Remediation Project
The Buzzards Bay Project is working with the Town of Marion, Massachusetts, to
reduce pollutants associated with storm water runoff entering Spragues Cove.
Spragues Cove is a small, shallow embayment on the shore of Sippican Harbor.
Currently its three-acre area of valuable shellfish beds is closed for shell-fishing
because it exceeds both state and Federal bacteria standards for shellfishing.
The largest storm drain system drains approximately 64 acres of watershed directly
in the Cove. The mitigation project will incorporate the use of a constructed wetland
system to treat the "first flush."
Strategy and Rationale
Several treatment alternatives for the storm water draining into Spragues Cove were
considered:
No action. The drainage system continues to function and shellfishing
areas remain closed because of high fecal coliform counts
Mechanical treatment methods such as chlorination, ultraviolet light,
ozone and reverse osmosis
Physical methods of treatment such as infiltration, settling or
constructed wetlands
The Town of Marion reviewed the alternatives and decided that a constructed
wetland system met the objectives of the project. The system will include a settling
basin, marshland vegetation, and an open, deep water pool. The settling basin allows
for coarse sediments and particulates to settle out prior to entering the wetland
treatment system. In the wetland itself, physical and biological processes will treat
and remove pollutants from the water. The restored wetland system will have a
hydraulic detention time of over 14 days.
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The wetland system will be constructed where a salt marsh previously existed. The
site was filled decades earlier with dredge spoil from nearby Sippican Harbor. In
addition to providing water quality improvements, the restored wetlands system will
enhance the fish and wildlife habitat in the area. Currently the site has little habitat
value.
Effectiveness
Existing research on using wetlands to treat wastewater for fecal coliform indicates
that at least 95 percent or greater is typically removed. Fecal coliform counts
associated with storm water from the Spragues Cove outfall are significantly lower
than previously recorded levels. The water quality monitoring plan will be part of
the quality assurance/quality control (QA/QC) plan required by the U.S.
Environmental Protection Agency.
Costs and Funding
The Town of Marion and the Buzzards Bay Project obtained $25,000 through the
Massachusetts Department of Environmental Protection's 319 grant program. The
Town provided an in-kind match valued at $35,000 to cover the cost of construction,
equipment and labor. The Town also donated the land on which the wetland system
will be constructed (estimated value of $100,000 per acre). A total of two to three
acres of land will be utilized for the project at a total cost of $200,000 to $300,000.
Additionally, the U.S. Fish and Wildlife Servide granted the Town $10,000 for the
project under the Wetland Restoration Program. Planning and technical assistance
will be provided by an interdisciplinary team from the Soil Conservation Service
(SCS).
4. Broad Marsh River Storm Water Remediation Project
Broad Marsh River is a tributary to the Wareham River estuary. It is located in the
Town of Wareham in the northern part of Buzzards Bay. The entire Broad Marsh
River has been closed to shellfishing and some beaches closed to swimming due to
high fecal coliform concentrations. The most significant source of pathogens and
fecal coliform pollution in the river is associated with storm water runoff from
discharges from adjacent storm drain systems. Other potential sources, such as
migratory waterfowl and boats, have been deemed insignificant.
The primary objective of the storm water remediation project is to reduce the amount
of pollution (mostly fecal coliform) from storm water runoff entering Broad Marsh
River.
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Strategy and Rationale
Several alternatives were considered for the treatment of storm water runoff from
storm drain systems adjacent to the Broad Marsh River:
No action. Fecal coliform pollution would continue unabated and result
in the continued closure of shellfishing beds and many beach closures
for swimming.
Extended detention basins, wet ponds or constructed wetlands would be
used to detain the first flush of runoff for at least 24 hours.
Infiltration structures such as infiltration basin at the end of each storm
drain system, or a series of leaching chambers under the existing road
surface
The selected alternative was the use of leaching chambers placed under the road
surface. The rationale for selecting this alternative is typical in many retrofit
situations; detention basins were rejected because, as an "end-of-pipe" practice, they
require considerable commitment of land to function properly. Since there are 16
storm water outfalls to this section of the Broad Marsh River, there would have to be
16 detention basins and this would require the acquisition of a large amount of land,
including some dwellings. This choice was not deemed feasible. Infiltration basins
located at the end of a pipe have a similar need for large land commitment. The
leaching chamber option was chosen because leaching'chambers placed under the
road surface would minimize the disruption to the present drainage system and
would not require a large land commitment.
Effectiveness
This project is not yet fully established. However, to demonstrate the effectiveness of
the leaching chambers, the project will monitor a minimum of three chambers.
Costs and Funding
The Buzzards Bay Project was initially unable to fund the Broad Marsh River project.
However, the Buzzards Bay Project together with the Town of Wareham, requested
funding under the Massachusetts Department of Environmental Protection's 319
(Nonpoint Source) Program and successfully secured funding in the amount of
1,450 to help reduce pollution loadings from storm water runoff.
5. Town of Yarmouth
In 1991, the Town of Yarmouth implemented the retrofit of a drainage system to
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eliminate the direct discharge of storm water runoff containing high fecal coliform
counts to the Bass River. The drainage system was retrofitted to direct the flow into
a retention basin to allow storm water to percolate through a gravel bed. This design
also allowed for evaporation to remove pollutants. The retrofit substantially reduced
fecal coliform counts from pre-retrofit levels and improved the water quality in
several ways:
it has reduced velocity, encouraging infiltration
it further reduced the velocity through infiltration and
evaporation
fecal coliform counts are lower even after similar pre-retrofit
rainfall events
Effectiveness
Water quality monitoring performed by the Barnstable County Department of Health
Laboratory both before the retention basin retrofit and afterward revealed
substantially reduced fecal coliform counts.12
6. Town of Orleans
The Town of Orleans, Massachusetts is a community on Cape Cod which has
extensive coastal waters, including three estuaries. These waters contain important
commercial shellfishing areas. In 1988, several areas within the Town's waters were
closed to shellfishing due to bacterial contamination. Through sampling of storm
drain outfalls and receiving waters, and from a review of existing water quality data,
the Town identified storm water runoff as a significant source of contamination from
bacteria and other pollutants to its coastal waters.
Strategy and Rationale
Three drainage areas were targeted as having significant adverse impacts on water
quality in sensitive areas and in need of remediation. The Town's strategy was to: 1)
identify the three high priority areas for development and implementation of
pollution control measures; 2) establish a storm water management committee; 3)
screen BMP alternatives to choose best available means to remove bacteria and solids;
and 4) appropriate funds for study of conceptual approaches and engineering designs
and for construction of the BMPs at the three high priority sites.
12 Town of Yarmouth, "Effects of Route 6 Storm Drainage
Improvements on Water Quality in Bass River," November 11, 1992.
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Prior to undertaking the projects, which are scheduled for completion in May, 1993,
the Town acted on the consultant's recommendations and took the following actions:
scoped potential solutions
focus on BMPs for control of bacteria and solids
prior to choosing BMPs, Town conducted field investigations, which
included the following steps:
mapping drainage systems
analyzing pollution treatment alternatives
sizing treatment facilities
designing O & M programs
The BMP selection process identified the most feasible and cost effective practices for
use in the three drainage systems which were to be retrofitted. In addition, the Town
of Orleans Storm Water Quality Task Force was set up to insure the project's
technical quality and to address local concerns.
A range of BMPs were considered for control of bacteria and solids and their
associated nutrients. The following BMPs were considered for this project, because
they are targeted for the control of solids and bacteria:
extended detention ponds
retention basins
infiltration trenches (subsurface leaching gallies)
filtration beds
A system of sub-surface leaching gallies was used at three sites because of limited
land but suitable soil conditions; one site consisted of a detention basin upstream of
a filter bed structure because soil conditions were too poor to permit infiltration.
Institutional Issues
The Town's principal institutional motivation for implementing the retrofit projects
was the adverse economic impact of closed shellfish beds. Abating and controlling
the bacterial contamination from storm water runoff was directly tied to economic
concerns and this was a very strong motivation for the Town to organize a task force
and to act on the problem. The Town appropriated funds to develop conceptual
approaches and engineering designs, as well as for the construction of the necessary
BMPs.
II. Regional Cooperation: Role of the Cape Cod Commission
The Cape Cod Commission works with towns on Cape Cod on various matters
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including local transportation projects. In Barnstable County, shellfish bed closures
were the principal motivation for the Commission to become involved with storm
water issues. The Commission trys to de-politicize issues and use all "levers"
available, including state environmental review processes, such as coastal zone
management consistency review, to affect outcomes.
Strategy
The strategy employed by the Cape Cod Commission utilizes several different
components to maximize the leverage which the Commission can employ to facilitate
implementation of storm water retrofit projects on Cape Cod. They try to use all the
"levers" available, such as coastal zone management consistency review and the
implementation of the Buzzards Bay Management Plan as part of the National
Estuary Program (EPA). The Cape Cod Commission works as a coordinator [much
like MWCOG in Anacostia watershed restorations] with the Massachusetts
Department of Public Works (Mass DPW) and local governments on storm water
remediation and retrofitting as part of local transportation projects.
The Cape Cod Commission (through the Cape Cod Marine Water Quality Task Force)
has developed a process for prioritizing storm water drainage mitigation projects.
This process includes the development of a numerical index to rank proposed
projects. The worksheet is keyed to the concerns o'f Barnstable County, viz., the
safety and harvestability of shellfish beds, as well as the safety of areas used for
swimming and recreation.
For more information...
For more information about the Buzzards Bay Project and other programs in
Southeastern Massachusetts, call the Buzzards Bay program office at (503) 748-3600.
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City of Austin, Texas
Background
The City of Austin, Texas, stretches from the Texas hill country of the Edwards
Plateau, eastward to the Blackland Prairie and the Gulf Coastal Plain. A unique
environment results from this rapid geologic and ecologic transition.
The Colorado River flows directly through the City. Three riverine lakes - Lake
Travis, Lake Austin and Town Lake - are the three most downstream reservoirs of a
chain of reservoirs on the Colorado River known as the Highland Lakes. These
reservoirs are the City's main water supply, as well as being tourism and recreational
resources.
Another key water resource in the area is the Edwards Aquifer, a limestone aquifer
on the western side of the City. The aquifer is the sole source of water supply to
several communities south of Austin.
These water resources are potentially threatened by water pollution resulting from
storm water runoff and other sources of nonpoint pollution. In response to this
threat, the City has developed one of the best watershed protection programs in the
country. The keystone of this program is the Comprehensive Watersheds Ordinance.
Development of the Comprehensive Watersheds Ordinance
In order to protect water resources from degradation due to urban nonpoint source
pollution, the City enacted several watershed protection ordinances in 1988. These
ordinances were combined into a single code which applies to the entire city and to
its extraterritorial jurisdiction. The City of Austin Land Development Code and the
Environmental Criteria Manual provide guidance for water quality management. The
1988 regulations became the basic building blocks of the Austin storm water
management and BMP implementation and retrofit program.
The original catalyst for the consolidation of the existing watershed protection
ordinances was the comprehensive planning effort known as "Austin Tomorrow."
This plan identified nonpoint source pollution as a potential threat to Austin's
environmental and economic well-being.
Monitoring of Austin's creeks and lakes followed this study and in 1978 the Lake
Austin Watershed Ordinance became the first water quality related ordinance and
nonpoint source pollution control ordinance to be adopted in the region.
In 1981, the City of Austin joined the EPA-sponsored Nationwide Urban Runoff
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Program (NURP) study and began monitoring its storm water structural controls in
1982. Subsequent watershed protection ordinances were passed from 1980-1984 to
cover additional environmentally-sensitive areas.
By 1986, the City of Austin had had eight years of experience with watershed
protection ordinances and appointed the Comprehensive Watersheds Ordinance Task
Force to develop the consolidated ordinance and provide final review and
recommendations for implementing the consolidation of the numerous existing
ordinances.
Overview of the Comprehensive Watersheds Ordinance
The Comprehensive Watersheds Ordinance (CWO) was directed at preventing urban
runoff pollution by placing requirements on proposed new development with Austin
and its extraterritorial jurisdiction. Although the Comprehensive Watersheds
Ordinance originally existed as a stand-alone document, it has since been
incorporated into the City's Land Development Code. In addition, there have been
several amendments to it since 1986 and more are anticipated in the future to better
protect various sensitive areas. Nevertheless, knowledge of the evolution of the
Ordinance is helpful to understanding Austin's strategy for urban nonpoint source
pollution control.
Specific pollutants were not addressed in the Comprehensive Watersheds Ordinance.
Control of specific pollutants was instituted only for the sensitive Barton Springs
Zone, which recharges the Edwards Aquifer. Several ordinances for the protection of
this sensitive area have been put in place over the last several years.
The Ordinance required a range of widely accepted and proven structural and
nonstructural nonpoint source pollution controls to be included in new development
projects. These controls included best management practices (BMPs) such as
impervious cover limitations, water quality buffer zones, protection of critical
environmental features, limitations on disturbance of the natural stream, erosion
control practices, sedimentation and filtration basins, and wastewater disposal
requirements. One significant aspect of the ordinance was the use of nonstructural
controls to prevent and mitigate nonpoint pollution associated with development.
The rationale behind this approach was that impervious cover limitations and buffer
zone requirements have been proven to maintain the basic hydrologic balance.
Protection of non-drinking water supply watersheds in the eastern side of Austin
were not given high priority. Downstream of Town Lake the Colorado River is not
used for drinking water supply. Furthermore, clay soils dominate on the eastern side
of the City; therefore, maintaining infiltration and recharge is not a critical goal in
these watersheds.
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Effectiveness of the Ordinance
The City of Austin standard sand filter design requires the first half inch of runoff
from a site to be diverted into a sedimentation basin and then filtered through sand.
This design is based on eight years of monitoring filter ponds of different designs.13
The demonstrated removal efficiency of the sedimentation/filtration ponds for total
suspended solids is 75% to 97%.
An important consideration learned from the Austin experience regarding
effectiveness is that maintenance is critical to ensure BMP effectiveness, yet timely
maintenance is problematic at both a local and nationwide level. Another is that the
best protection for water resources is believed to be afforded by a combination of
structural and non-structural controls as provided for in the Comprehensive
Watersheds Ordinance. Structural controls alone are not always effective, nor can
they prevent an increase in pollutants from high intensity developments.
Austin's non-degradation strategy for contributing watersheds is to limit the percent
of impervious cover in new developments and to reduce post-development pollutant
loads through a menu of storm water control practices, and a program of retrofitting
storm water treatment measures in developed areas. Austin has incorporated this
strategy into the framework of the City of Austin Land Development Code through a
mechanism known as an "impervious cover cap." The impervious cover cap is
established by setting a Maximum Sustainable Removal Rate for storm water
treatment measures at 90%; beyond this point, storm water control measures cannot
be relied upon to reduce the pollutant loads associated with additional impervious
cover down to the pre-development level.
This strategy aims to reduce excessive reliance on storm water treatment measures
because of their inherent limitations and risk of failure due to lack of maintenance
and their need for replacement. Impervious cover levels, on the other hand, do not
change over time, do not require maintenance, and their life span is infinite provided
their nature is unchanged.
However, the Austin program recognizes that modification of the City's development
regulations would provide only a partial solution to the problem of water quality
degradation. It sees retrofitting of structural storm water controls as the only way to
reduce pollutant loads from existing development and development projected but not
13 Parrish, John H. and Stephen Stecher, "Nonpoint Source
Pollution Control in the City of Austin." City of Austin,
Environmental and Conservation Services Department, March '1991,
p. 5.
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yet built.14
The Austin program has recognized that, in light of the growing trend toward
limiting building density and/or impervious cover as a means of nonpoint source
control in residential areas, there is a need to establish a clear linkage between
development density or impervious cover and pollutant loadings. In addition, the
city recognized that more study is needed on the effects of types of land use on the
quality of storm water runoff.
The City's Storm Water Monitoring Program has provided the city an opportunity to
evaluate the effectiveness of its varied array of storm water quality controls, and also
to assess whether they are over- or under-designed relative to site conditions.
First Flush of Runoff and its Effects on Storm Water Control Structure Design15
Austin's Environmental Resource Management Division published a report (1990)
showing that the first 1/2 inch of runoff did not necessarily carry the bulk of the
storm load. This was contrary to the prevailing assumption that the first 1/2 inch of
runoff in a storm washes off 90% of pollutants from the impervious cover. The
report suggested that for a development with 90% impervious cover, only 40% of the
total storm load would be washed off in the first 1/2 inch of runoff.
The implication of the report for control structure design was that a control structure
designed to capture and treat only the first 1/2 inch of runoff would only remove
about 40% of the total annual load. The bypass or untreated annual load could be
substantial. The report did not suggest an alternative structural control design; it
merely raised the issue of a substantial amount of pollutant load in excess flow from
a structure designed to capture and treat the first 1/2 inch. Changes to the City's
Land Development Code in December 1993 resulted in the treatment volume
increasing with the amount of impervious area on the site, starting at .50 inch plus
.10 inch per 10% increase in impervious cover over 20% of the site.
However/ urbanized watersheds should be targeted for priority control based on
other findings. Another Austin study confirms that storm water runoff pollutant
loads increase with watershed imperviousness, and that loading rates of urbanized
14 Ibid., p. 15
15 City of Austin, Environmental Resource Management
Division, "The First Flush of Runoff and Its Effects on Control
Structure Design." June, 1990.
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creek watersheds were significantly higher than those from small suburban sites.:fi
Sand Filter Program
The City of Austin has developed a sand filtration best management practice for use
in storm water quality management. The sand filtration systems are the primary
water quality control structures.
The City had previously implemented a storm water monitoring program in 1984.
This study was conducted to determine annual removal efficiencies of six storm
water quality control structures, including three filtration basins, one wet pond, one
sedimentation (dry) pond, and one retention/filtration basin system. The structures
were monitored between 1984 and 1989, and comparative measurements of inflows
and outflows were taken to determine concentrations of pollutants.
Effectiveness of removal for the following parameters was measured:
Fecal coliform
Total suspended solids (TSS)
BOD/COD
Nitrogen
Phosphorus
Heavy metals
The study17 concluded that the sand filtration basin is an effective structural control
measure for most of the described pollutant parameters. Sand filtration is a
demonstrated success in Austin, although officials concede that maintenance is
sometimes inadequate and sporadic.18 There have also been some isolated technical
and/or design failures, such as slope erosion and construction failures which have
resulted in inadequately performing BMPs.
"City of Austin, Environmental Resource Management
Division, "Stormwater Pollutant Loading Characteristics for
Various Land Uses in the Austin Area." March, 1990.
17City of Austin, Environmental Resource Management
Division, "Removal Efficiencies of Stormwater Control
Structures." Final Report, May 1990, p> 16.
"Personal communication with Les Tull, Engineer, City of
Austin, Texas, May 25, 1993.
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Strategy
The Austin sand filter program was implemented in response to regulator)'
requirements, viz., the consolidation and enactment of several watershed protection
ordinances in 1988. In addition, political pressure to act came from citizens
demanding action to protect water quality. The City of Austin's Land Development
Code and Environmental Criteria Manual provide documentation and guidelines for
the City's water quality management efforts. - - , . -
'" -.-*", *%**
Prior to enactment of the watershed protection ordinances, the City implemented a
storm water monitoring program in 1984 to evaluate storm water control measures
and to develop a database to quantify the effects of impervious cover and land use
on water quality and also to evaluate the effectiveness of various structural storm
water control measures already in use.
The basic strategy and philosophy guiding the Austin program has been to make .
new development and redevelopment pay the costs attributable to its impact and to
mitigate all impacts of new development. While this has been the strategy, it has not
been possible to accomplish this for all aspects of the development process, such as
permits and review. In addition, the City assumes responsibility for maintaining
water quality controls for single-family development. This approach includes a
provision for payment of a fee in lieu of constructing BMPs so as riot to restrict
development. "Fee in lieu of" funds are used for retrofit projects for existing
development, but only within the most highly urbanized and developed watersheds
classified as "urban" in the Land Development Code.19
There are many components to the Austin storm water management amd urban
nonpoint pollution control program. These include retrofit watershed master
planning, source control of pollutants, and public education. A current emphasis is
on the public education component, which includes videos and posters with the
theme of abating urban nonpoint source pollution.
Austin's strategy sees the key to a successful nonpoint source control program as the
targeting of critical areas to achieve high pay-off returns. The City's focus is on
potential deterioration of local water supplies, viz., Lake Travis, Lake Austin, Town
Lake and the Edwards Aquifer. The Comprehensive Watersheds Ordinance requires
the strongest nonpoint source controls in those developments in watersheds which
contribute to the drinking water supply.
Targeting new development is seen as a cost effective method of preventing future
nonpoint source problems. Required controls which are prescribed in the Ordinance
19 Ibid.
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can be included in the initial land planning. Since the primary controls set forth in
the Ordinance are non-structural, raw land cost is the main cost for new development
associated with nonpoint source controls. However, structural controls are also used
and these have a cost to the developer. Since impervious cover limitations are the
most important non-structural control specified in the Ordinance, retrofitting existing
development has proven to be difficult. Retrofitting structural controls has also been
difficult, due to limited location and high land costs.
The City's retrofit program uses public education as its main tool to build and keep
the necessary public support for storm water management programs through the use
of videos, posters, and other media. In addition, Austin has initiated a process of
storm water retrofit master planning as a way of maximizing the scarce public
resources available for this purpose.
Developing a strategy for controlling nonpoint source pollution from urbanized
watersheds is particularly difficult, and much more complex than preventing
nonpoint source pollution from developing watersheds. Retrofitting BMPs in urban
areas is still a "pioneering" activity and involves considerable experimentation and
cost. While there are an increasing number of localities pursuing retrofit strategies,
there is no broad national experience with retrofit implementation.
BMP selection in retrofit situations is also problematic; for example, wet ponds are an
excellent BMP for controlling nutrients, yet they are often very difficult to site under
retrofit conditions.
Non-degradation Strategy20
Austin has developed a non-degradation strategy for a particularly sensitive and
important area known as the Barton Springs Zone, which covers several watersheds.
The strategy is "design-based" rather than being entirely a technology- or
performance-based approach. The design-based approach requires that compliance
be designed into a project before it is built based upon best available scientific and
engineering principles. This strategy includes a City-funded program for retrofitting
storm water controls.
Other elements of the non-degradation strategy include:
strengthening existing regulations by limiting exemptions
limiting impervious cover to levels at which generated pollutants can be
20Parrish/Stecher, "Nonpoint Source Pollution Control in the
,City of Austin," March 1991., p. 12
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reduced to background levels by an array of storm water control
practices
Importance of Non-structural Controls in Austin's Program
One of the distinctive features of Austin's storm water management strategy is the
emphasis given to the use of non-structural controls. The basic assumptions of this
approach are the following:21
structural controls alone cannot prevent an increase in pollutants from
high intensity development
maintenance requirements are high for structural controls compared to
the maintenance needed for impervious cover limitations and buffer
zones
sole dependence on structural controls is not wise for protecting the
City's water resources; a combination of structural and non-structural
controls is the best strategy
Institutional Issues
Austin created a city department of environmental conservation, the Environmental
and Conservation Services Department, in 1987. Its central focus is resource
conservation and environmental protection, as distinct from public works. This
department is co-equal with other City departments. It oversees the work of public
and private agencies under its jurisdiction. This institutional arrangement is clearly
intended to provide support for effective environmental and regulatory (enforcement)
action.
The Environmental and Conservation Services Department and the Department of
Public Works "share" a drainage utility (storm water utility). Drainage projects are
funded with fees from the drainage utility. "Storm water" is not separately identified
on the utility bill, nor described as such officially.
Costs and Financing
Most storm water programs are funded by the drainage utility, or drainage fee.
Public works drainage projects in the Capital Improvements Program are paid for
with bond sales which are repaid with tax (general fund) revenues at this time.
21Parrish/Stecher, "Nonpoint Source Pollution Control in the
City of Austin," p.6
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Development is expected to "pay for itself," that is, development must pay for the
cost of controls associated with that development. However, in reality, development
fees pay for approximately 30% of the land development review and permit
programs. Nevertheless, the program's emphasis on non-structural controls means
that the cost for the City is considerably lower (because of less monitoring and
inspection) than if structural controls were the sole means of control.
The Austin program also takes the view that preventing adverse water quality
impa"cts from nonpoint source pollution- is much less expensive than ti^ift^-t
.water quality after it has been degraded. One of the stated goals of the '
Comprehensive Watersheds Ordinance is to avoid the cost of retrofitting existing
f * ' 1ir ** *'
development.
There are significant costs throughout the institutional structure related to control of
nonpoint source pollution. Preventing NFS pollution can avoid or reduce other costs
such as wastewater treatment, the need for dredging lakes and waterways, and
health risks associated with toxics pollution. The Austin view is that the cost of
restoration, retrofitting, dredging, advanced types of water treatment, development of
new water supplies, and lost recreational and economic values can easily dwarf the
cost of prevention.22
Other NFS Control Programs
The City of Austin has also initiated non-structural and low-structural development
controls to limit impervious surface areas for storm water management purposes.
- They have established a critical zone in which no construction is allowed, as well as a
transition zone where development is limited or not allowed in order to preserve
riparian areas.
Other programs which the City has instituted to control urban nonpoint source
pollution include the following pollution prevention and source control programs:
household hazardous waste collection: provides for safe disposal of
hazardous materials
street cleaning and litter collection program
xeriscape and integrated pest management (IPM) programs: minimizes
inputs to the environment from fertilizers and pesticides; both
approaches stress the minimal use of the least harmful substances to
control pests and weeds; IPM is encouraged in municipal operations
22Parrish/Stecher, "Nonpoint Source Pollution Control in the
City of Austin," p.7
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BMP Siting Considerations
There is a diversity of opinion as to whether it is better to construct large regional
BMPs or numerous smaller BMPs closer to pollutant sources. The preferred
approach in Austin is to construct numerous smaller BMPs and capture water as
close to the source as possible for the following reasons:
1) need to capture less water to achieve the pollutant removal desired
2) capital and maintenance costs are less if the BMPs are smaller
3) maintaining the natural hydrology is easier with smaller BMPs - in
addition, the need for groundwater recharge is addressed, whereas if
channeling water further down the watershed was done, groundwater
recharge would not occur (or recharge of polluted water could occur
before the runoff reached the treatment device)
4) protection of smaller waterways from pollution and channel erosion
Summary and Conclusion
Austin has attempted to come to terms with its nonpoint source pollution problems
through implementation of the Comprehensive Watersheds Ordinance and other
ordinances since 1986. The City recognizes the actual and potential costs of nonpoint
source pollution as it relates to safeguarding of drinking and groundwater supplies,
maintaining tourism and recreational opportunities, and protecting wildlife habitat, to
name a few.
Austin is "ahead of the curve" in terms of meeting EPA and state water quality goals.
These efforts will continue to pay benefits into the future. The development and
implementation of the Comprehensive Watersheds Ordinance could be a model for
other local governments in their efforts to control nonpoint source pollution.
Relevance of Austin's Watershed Approach for Other Jurisdictions
Austin's Comprehensive Watersheds Ordinance is easily transferable to other
jurisdictions and to other hydrogeologic conditions. The Texas Water Commission
cited Austin's Ordinance as-an example of the kinds of controls which local
governments in Texas could implement as part of the Nonpoint Source Management
Plan which the state submitted to the U.S. Environmental Protection Agency.
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Because the Ordinance is based on BMPs instead of on design or performance
standards, it is widely applicable to other situations and does not require specialized
staffs for its implementation. The Ordinance is accompanied by a technical manual
which specifies the technical aspects of the controls which it requires.
Numerous other jurisdictions in Texas have adopted watershed protection ordinances
based on the same framework as Austin's. Governmental entities across the country
have requested copies of the Comprehensive Watersheds Ordinance for guidance on
how to protect their water resources and control nonpoint source pollution.
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Austin's Program at a Glance
Steps to Implementation
1) Comprehensive Planning Process: "Austin Tomorrow"
2) Appointed Watershed Ordinance Task Force
3) Consolidation of Watershed Protection Ordinances
4) Passed Comprehensive Watershed Ordinance
5) Targeting of Critical Areas: Austin's strategy uses targeting of
critical areas to achieve cost effective control.
Controls for New Development
Identify Candidate Retrofit Sites
Retrofit Program
A strategy for controlling nonpoint source pollution from urbanized watersheds
involves considerable coordination, experimentation and cost.
1) Use Public Education to Build Support
2) Use Retrofit Master Planning to Maximize Scarce Resources
For more information...
For more information about the City of Austin's program, call the Environmental
and Conservation Services Department at (512) 499-2501.
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City of Orlando, Florida
Introduction
The City of Orlando, Florida has taken a pioneering role in trying to solve its water
quality problems related to urban storm water runoff. Protection of its numerous
lakes and wetlands has been a primary motivation for action. Within the corporate
limits of Orlando there are some 83 named lakes, which lie within five major
drainage basins. The City has the distinction of having been designated a "National
Storm Water City of the Year" by the U.S. Environmental Protection Agency. It
earned this distinction because of its aggressive storm water management and retrofit
program. .
Some of the innovative storm water treatment systems and retrofit methods used in
Orlando include storm water wetlands, alum injection, exfiltration, lake aeration,
sediment control devices, trash screens and shoreline and littoral zone vegetation.
Some of the other approaches being used in Orlando are:
storm drain retrofits and water quality enhancements when performing
corrective maintenance (e.g., vertical volume recover}7 unit for drainage
to Lake Lawsona)
exfiltration basin retrofits to existing city storm drains
littoral zone enhancement and revegetation with native aquatic plants
creation of storm water wetlands for pre-treatment of runoff entering
lakes (e.g., Lake Lorna Doone)
depressional landscaping to encourage runoff infiltration (e.g., Lake
Ivanhoe)
One of the many major retrofit projects in the Orlando area is the Lake Greenwood
urban wetland, which is a wetland and storm water management system in an urban
environment close to downtown Orlando.
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Evolution of the Florida Storm Water Program/Major Regulatory Components
The major components of Florida's storm water program are three pieces of
legislation: the 1982 storm water permit requirements for new development; the 1987
Surface Water Improvement and Management Act (SWIM), which provided a
framework for watershed planning; and the 1989 storm water legislation, which
established program goals and extended program coverage to existing agricultural
and forestry sources.
The Surface Water Protection and Management section of the 1989 storm water
legislation provides the regulatory framework for the Florida storm water
management program, particularly the watershed approach. This program was
enacted by the Florida legislature to restore the state's degraded water bodies and to
protect those still in good condition.
The landmark 1989 storm water legislation was intended to integrate the various
existing storm water laws and programs into a comprehensive watershed
management program. Most importantly, the 1989 law emphasized the watershed
approach to correcting existing storm water deficiencies and it gave a regulatory
impetus to retrofitting. The 1989 law also established the State Storm Water
Demonstration Grant Program which provides matching grants for. storm water
treatment projects undertaken by local governments which have implemented storm
water utilities. The grant program is clearly an inducement to Florida municipalities
to set up storm water utilities.
Lessons Learned in Florida's Storm Water Program
The Florida storm water program has been successful at minimizing storm water
problems associated with new growth, but it has been much less successful in
restoring water bodies degraded by storm water discharges. The piecemeal approach
cannot address one of the state's largest problems, however, the problem of
retrofitting drainage systems, which includes:
retrofitting of existing storm water drainage systems to reduce pollutant
discharges to state waters
correcting storm water infrastructure deficiencies related to the state's
rapid growth
Livingston stresses that the solution is comprehensive and coordinated work
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throughout the watershed.23 He emphasizes the need to address land use, water
resources, and infrastructure planning within a watershed context. He also states
that a dedicated funding source, such as a storm water utility is also important for
maintaining an effective program.
Lessons Learned in Orlando
The Orlando experience suggests that one of the requirements for successful urban
runoff control and retrofit projects is the importance of control of the project and the
need to write very good specifications so that water quality goals are met. Engineers
and consultants may have an economic incentive to design BMPs which may not be
commensurate with the implementing authority's water quality goals.
Experience reveals that engineers and consultants may sometimes have a mechanistic
approach to problem solving and therefore advocate a hydraulic solution rather than
water quality one in some instances. They know how to get the water off-site as
quickly as possible, but this is not necessarily commensurate with a water quality
solution.
The best way for the implementing authority to ensure success is to be in control of
the project, to know the solution that is necessary, and then see that it is done
correctly.
Greenwood Urban Wetland
The Greenwood Urban Wetland in Orlando is a constructed urban wetland located
within a 522-acre drainage basin. Storm water runoff collected within the 522-acre
sub-basin flows into Lake Greenwood, which lies at the lowest point in a 4.5 square
mile urbanized area. The artificial wetland was built to alleviate flooding, to pre-
treat storm water runoff prior to discharge into drainage wells (which discharge
water to the upper Floridan acquifer), and to re-use the stored water to irrigate an
adjacent cemetery and park. City-owned land which was previously vacant was
excavated to form a series of ponds and a bypass stream leading to five drainage
wells.
The storm water quality enhancement component of the wetland plan came about as
a result of the City's concern for protecting its groundwater supply. Proximity to
groundwater is a prime concern in most of Florida.
"Livingston, Eric H., "Lessons Learned from a Decade of
Stormwater Treatment in Florida." Bureau of Surface Water
Management, Florida Department of Environmental Regulation,
Undated.
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The storm water "treatment train" concept was incorporated into the Lake Greenwood
urban wetland. The BMPs included in this treatment train are: a sediment and trash
screening device; a littoral zone with vegetation; and aerators to increase
microbiological activity.
Effectiveness of the Greenwood Urban Wetland
Water quality monitoring of Lake Greenwood was begun in 1987 - one year prior to
the beginning of construction of the wetland. This was done to obtain a baseline
profile and to ascertain the trophic state of the lake. Both before and immediately
after construction, the lake exhibited eutrophic to hyper-eutrophic conditions. After
completion of the project, the lake's trophic state indices were in the mesotrophic
range.
Prior to construction, the water quality of Lake Greenwood was not in compliance
with Florida Class III (recreation and wildlife propagation) water quality standards.
Since construction, there have been no water quality standards violations of any
parameters tested, including EPA-listed pesticides. Further monitoring of the storm
water treatment system is being planned for wet weather pollutant removal
efficiencies and further hydraulic analysis. An ongoing storm water monitoring
program was begun in 1991.
Based on the preliminary sampling data, it is clear that the Lake Greenwood urban
wetland storm water management system has enhanced water quality within the lake
and also the quality of the water discharged to the drainage wells (which discharge
to a major acquifer).
Development of Orlando's Storm Water Utility
Storm water projects in Orlando have traditionally been financed out of general fund
revenues, as is common in most municipalities. In addition, Orlando has used
revenue from a state gasoline tax for projects which also have a road/transportation
component. Depending upon general fund revenues, however, often results in
projects being deferred to pay for more critical governmental functions such as police
and fire. The City has adopted an aggressive program of storm water system repair
and replacement, pollution control, and lake enhancement. This problem has been
funded in the past through the City's general property tax budget, but this source is
no longer adequate for the scope of the problem today, particularly in view of
increasingly stringent state and Federal water pollution control requirements.
To provide for the effective management and financing of a storm water system
within the City of Orlando, the City established a storm water utility. The storm
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water utility generates its revenue through user fees. A storm water service charge i±,
levied on every parcel of land in the City. The fee is based on the amount of storm
water which a particular parcel passes on to the storm water drainage system.
The storm water utility is responsible for the operation, construction and maintenance
of storm water management devices, for storm water system planning and lake
management.
Packed Bed Storm Water Filter Artificial Wetland24
One innovative project which was proposed by the City and implemented through a
consultant was the "packed bed filter." This experimental storm water BMP will be
used (just coming on line in July 1993) to treat a small but highly urbanized portion
of the drainage basin which flows into Clear Lake. The project was initially proposed
in response to concerns about the lake's water quality.
The drainage basin for Clear Lake consists of over three square miles of highly
developed urban area. This retrofit technique became necessary because best
management practices (BMPs) for new development are not appropriate in the highly
urbanized and completely built-out Clear Lake basin. This innovative method of
storm water treatment was selected both for its presumed pollutant removal
efficiency, as well as the necessity of using a BMP which could function within a
limited area where land utilization constraints exist.
The packed bed filter is an example of technology transfer - a common wastewater
treatment technique which has application to urban storm water pollution treatment.
The filter utilizes a treatment train of two components, one of which is a packed bed
filter system planted with wetland macrophytes for nutrient uptake. Put more
simply, the system is a packed-bed filter (similar to a trickling filter) with
hydroponically-growing aquatic plants. During dry weather or low flow conditions,
the device will treat water from Clear Lake using the continuous flow to maintain the
planted beds.
The device has a limited storage volume, so a decision was made that in order to
maximize the removal of the most pollutants, the goal would be to capture less than
the first one-half inch of runoff from a larger acreage than a greater amount from a
smaller acreage. It is hoped that this will result in the treatment of a dirtier waste
stream and reduce the amount of pollutants reaching the receiving waters of Clear
Lake.
24Dyer, Riddle, Mills & Precourt, Preliminary Engineering
Report: Packed Bed Filter. Prepared for the City of Orlando, FL,
April, 1991, p. 4-3.
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Pollutant Removal Efficiency Cosiderations for Packed Bed Filters
Although the packed bed filter implemented by the City of Orlando has only recently
been brought on line [July 1993], there are certain operational considerations for
packed bed filters as they relate to treating urban storm water runoff. Packed bed
systems intended to treat storm water do not have to meet the strict effluent quality
criteria that would be required for wastewater. Indeed, the concentration of
pollutants in storm water most closely resembles tertiary treated wastewater with the
exception of solids concentrations. This is one reason why the packed bed storm
water treatment system was designed to treat a larger flow with lesser removal
efficiency than a higher removal rate from a smaller flow.
The packed bed filter employs the concept of a "treatment train." The concept of a
treatment train of BMPs involves a series of unit operations designed to remove the
largest amount of contaminants from runoff, typically greater than the pollutant
removal achievable through individual unit operations.
The packed bed filter system is a new technology and a transfer of technology from
wastewater treatment systems to storm water management systems. As an
experimental practice for storm water treatment, many elements need to be
monitored for their relation to long-term effectiveness:
hydraulic residence time
bed media
plant materials for the packed beds
depth
travel length
velocity
liners
Use of Alum for Treatment of Storm Water Runoff
One technology showing promise is the use of alum to treat storm water runoff.
Two lakes in Orlando, Lakes Dot and Lucerne, and one in suburban Winter Park,
Lake Osceola, are having their storm water inputs from large urbanized drainage
basins pre-treated with alum. The alum treatment concept was initially tested on
Lake Ella in Tallahassee.
Alum treatment of storm water runoff was selected after an analysis of the pollution
abatement alternatives. Conventional storm water management techniques such as
retention, detention, or exfiltration were deemed not feasible due to space limitations,
or because of the poor infiltration capacities of watershed soils. The alum is injected
and mixes with the storm water in the storm sewer lines. Floe accumulation begins
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immediately and the floe settles on the lake bottom.
Alum injection is wastewater treatment technology being adapted to storm water
quality control. There is still some question whether it can be considered a retrofit
technology, but its use as a pollution abatement alternative involves many of the
hallmarks of a retrofit situation:
infeasibility of conventional storm water management techniques such
as retention/detention
infeasibility of using exfiltration systems due to limitations of available
space and poor infiltration capacities of watershed soils
Another Case Study in Florida
Lake Tackson Regional Storm Water Management System
Rapidly urbanizing areas in the Megginnis Arm watershed were causing water
quality degradation in Lake Jackson in Leon County near Tallahassee. A regional
storm water detention system was designed and constructed through a cooperative
effort of the Florida Department of Environmental Regulation, the Northwest Florida
Water Management District, and with funding from EPA's Clean Lakes Program and
the State of Florida. The facility consists of a wet detention pond with a heavy
sediment basin at the inflow, a sand filter system designed to filter particular
pollutants from storm water, and a three-cell constructed wetland designed to
remove dissolved pollutants such as nutrients.
Construction of the system was completed in 1983 at a cost $2,664,389. Maintenance
operations, which consist of sediment and clay removal from the top of the filter
fabric do not exceed $30,000 per year.
Effectiveness of the Lake Tackson facility
Florida State University researchers conducted a long-term storm water sampling
program of the facility and its individual components. Overall, the facility has
performed up to design specifications within the constraints of space and the
technical level of the equipment used. However, the increasing urbanization of the
watershed has resulted in larger volumes of storm water draining into the facility,
well beyond its design capacity. To overcome these deficiencies, the facility was
enlarged to provide longer detention of more storm water, allowing the facility to
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detain larger storms and limiting the discharge of untreated storm water into Lake
Jackson.
Lessons learned from Lake Jackson experience
Some of the lessons learned in the construction of the Lake Jackson regional storm
water management system include the following design considerations:
storage volume and the amount of water bypassing the system are
critical design elements; the system should be designed based on
maximum anticipated buildout in the watershed '
;-. -1- 'p'*1 ''-.'" *-. '-^jh''<^%! *», :'
adequate funding must be provided to operate and maintain the system
wetlands systems require some maintenance such as dredging to
remove accumulated sediments and organic matter; they will not work
indefinitely without maintenance
For more information:
For more information about the City of Orlando's program, call the Storm Water
Utility Bureau at (407) 246-2370.
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County of Fairfax, Virginia
Regulatory Context
Fairfax County, Virginia is subject to the following Federal and State legislation and
programs:
Amendments to the 1987 Clean Water Act requiring NPDES permits for
storm water discharges
Virginia storm water management regulations (at local option)
Erosion and Sediment Control Law
Chesapeake Bay Preservation Act
Section 404 of the Clean Water Act (wetlands protection)
Water quality requirements under the Reauthorization of the Clean
Water Act pending Congressional consideration in 1994
The County may also be subject to some requirements related to recent coastal zone
legislation to which Virginia as a coastal state would be subject. States must develop
a coastal nonpoint source pollution control program as a requirement of the Coastal
Zone Act Reauthorization Amendments of 1990 (CZARA). The State programs must
be approved by EPA and NOAA by 1995.
Background25
Fairfax County has been involved in storm water control for more than 30 years.
During the 1950s and 1960s, the emphasis was on storm water conveyance and
channelization, which included delineation of flood plains and implementation of
flood control projects. Beginning in 1972, on-site storm water detention was required
for all new development. In the 1980s, water quality BMPs were required for new
development in the southern areas of the County draining to the Occoquan reservoir,
the major source of drinking water for Fairfax County.
In addition to the Master Drainage Plans which were prepared for all watersheds in
"County of Fairfax, Virginia. Draft. National Pollutant
Discharge Elimination System. Municipal Storm Water Discharge
Permit Application, Part 2. November 1992.
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the County during the 1970s, a supplemental Regional Storm Water Management
Plan was prepared in 1988. This plan provides for regional storm water control
ponds to control both quantity and quality. Wherever opportunities exist, the County
intends to expand the implementation of regional storm water management ponds
from the current pilot project involving seven watersheds. Implementation of the
planned storm water control facilities over the past 20 years has resulted in
expenditures of approximately $60 million, financed primarily through storm bonds.
There are presently over 1,500 storm water management facilities located in the
County. In addition, there are 30 major lakes and over 100 smaller lakes and ponds
which function as BMPs and provide water quality benefits in Fairfax County.
In 1989, the Fairfax County Board of Supervisors adopted the "Regional Storm Water
Management Plan." The adoption of this plan marked a shift in philosophy on
implementing storm water management from reliance on on-site controls to what are
viewed as more effective regional controls.
Current Activities
The Fairfax County Department of Public Works is currently in the process of
obtaining various permits or implementing programs designed to provide water
quality improvements. These activities include:
obtaining an NPDES permit from the Virginia Department of
Environmental Quality; part 2 of the application has been submitted
and the County is awaiting approval from the State
implementing on-site best management practice (BMP) requirements for
new developments in Chesapeake Bay Preservation Areas to protect
water quality
implementing a regional storm water management program to provide
water quality improvements for both existing and new development,
and to protect downstream wetlands and habitat
implementation of stream channel erosion protection projects
adopted a Water Supply Protection Overlay District requiring BMPs in
the watershed of the County's water supply reservoir
re-zoned much of the Occoquan watershed [water supply reservoir] to
Residential/Conservation District (R-C) with 5 acre minimum lots
adoption of an Environmental Quality Corridor Policy to protect land
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and surface water resources
Ongoing Activities
As part of the County program to comply with NPDES requirements, there is a 5-
year monitoring program of selected storm water outfalls. The outfalls were selected
based on different land uses and, based on the final monitoring results, typical
pollutant loadings for each land use will be extrapolated.
There are approximately 44 regional storm water management facilities in the
Difficult Run watershed alone. The County currently spends approximately $1 to $2
million per year on capital construction for storm water control facilities. However,
prior to the recent downturn in the economy, typical drainage facility expenditures
totalled $2 million to $4 million per year. Due to current economic conditions, the
Fiscal Year 1994 appropriation has been reduced to $341,000.
To pay for these costs out of declining general fund revenues is becoming difficult for
the County and this has led to discussion about establishing a storm water utility as a
dedicated source of funding for storm water management and control. A storm
water utility feasibility study is currently in progress.
Role of the Chesapeake Bay Preservation Act
In Virginia, the Chesapeake Bay Preservation Act (CBPA) is a significant storm water
management program through its BMP requirements and use of buffers such as the
environmentally sensitive Resource Protection Areas (RPA). The regulatory
requirements of this program need to be considered by developers and local
governments such as Fairfax County, in addition to other storm water management
regulations.
Proposed Management Program
The County's proposed management program consists of the following elements:
continuation of ongoing requirements and programs such as
implementation of the Chesapeake Bay ordinance which requires
structural BMPs on all new development
implementation of suitable water quality control facilities
providing inspection and maintenance of storm water management
facilities
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increased public awareness of the importance of clean storm water
The County recognizes that the proposed management program will require
additional County funds and is currently evaluating the feasibility of establishing a
storm water utility to provide a dedicated funding source for storm water
management.
The County will look for opportunities to retrofit storm water devices and to
implement additional regional ponds in all the County's watersheds in existing
developed areas that are now without water quality controls. The County's
Comprehensive Land Use Plan also encourages the retrofitting of existing storm
water management ponds to become more effective BMPs.
Regional Storm Water Management Plan
In 1989, the County Board of Supervisors adopted a "Regional Storm Water
Management Plan" which proposed 134 regional ponds in the most rapidly
developing watersheds in the County. The adoption of this plan marked a shift in
Fairfax County's approach to implementing storm water management from onsite
controls to regional controls. This shift was based on the belief that regional controls
are more effective. Concerning the retrofit of existing facilities, proposed
development plans are reviewed by the Department of Public Works for
opportunities to implement regional storm water management to supplement the
pilot Regional Storm Water Management Plan for developing watersheds. In
addition, the feasibility of retrofitting existing or porposed flood management projects
to include water quality is evaluated.
Non-structural BMPs: Environmental Quality Corridors
Environmental Quality Corridors (EQCs) are the primary non-structural best
management practice used by the County to protect water resources. Although the
core of the EQC system will be the County's stream valleys, lands may be included
within the EQC system if they achieve any of the following:
habitat quality
corridor-like quality
aesthetic quality
pollution reduction capability
The stream valley component of the EQC system includes the following:
100-year flood plains and flood plain soils
soils with development constraints adjacent to wetlands, streams, and
steep slopes
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additional areas where above-described buffers are insufficient to
protect water resources
Current Funding/Future Funding of Water Quality Programs26
There are ongoing County water quality programs which are supported out of the
General Fund. These programs are:
monitoring programs
emergency response
public awareness
public facilities maintenance
The County's NPDES permit application clearly states the necessity of developing
new funding sources for implementation of capital improvement projects for water
quality.
The following point illustrates the tenuousness of funding water quality improvement
projects out of general or bond funds: The currently approved bond referendum
funds have almost been expended, and the latest storm bond referendum was
defeated by voters in 1990. Neither the general or storm bond funds can be relied
upon to provide stable funding for future storm water quality capital improvement
needs.
Yet the County estimates that $11.79 million per year will be required to implement
regional storm water management over the next decade, and to provide for
maintenance of these facilities. County staff are determining the feasibility of
establishing a storm water utility to provide long term capital as well as maintenance
funds for the County's storm water control facilities.
In the interim, two methods to fund capital construction of water quality control
improvements are being pursued. These are: use of storm drainage pro rata share
program funds; and proffer agreements with developers. Both of these sources are
relatively insignificant at the present time, due to the downturn in economic activity.
For more information...
For more information about Fairfax County's program, call the Storm Water
Management Branch at (703) 324-5800.
26 ibid.
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Cities of Eugene and Portland, Oregon
City of Eugene
Background
The City of Eugene developed its Comprehensive Storm Water Management Plan
(CSWMP) in response to Clean Water Act regulations requiring medium-size cities
and counties to improve and manage the quality of their storm water. The plan is a
model of a rational and comprehensive approach to dealing with the problem of
runoff from urbanized areas. From its beginning as a conventional program
emphasizing flood control and rapid conveyance of storm water runoff off-site, the
City has developed a plan which does not merely conform with, but exceeds, the
evolving Federal mandates for water quality management.
The principal motivation for initiating development of the Comprehensive Storm
Water Management Plan in 1991 was the imminent promulgation of a Federal
mandate (NPDES) requiring jurisdictions of medium size (between 100,000 and
250,000 population), to reduce discharges of pollutants to receiving waters from storm
water runoff.
The Comprehensive Storm Water Management Plan
The City's storm water management program goes further than meeting Federal and
state water quality requirements. It has taken the problem of meeting its legal
requirements and turned it into an opportunity to offer a broad-based solution
through a multiple objective approach to protecting, enhancing and restoring the
City's water quality.
The multiple objective approach of the Eugene plan includes storm water
management. Wetlands adjacent to Amazon Creek and other drainage channels are
considered to be hydrologically connected to the City's storm water conveyance
system. The plan recognizes the central role that wetlands play in storm water
management.
According to the plan, the five-year start-up phase of the storm water management
program includes major program activities such as planning and administration,
capital projects (including retrofitting), operations and maintenance, enforcement and
inspections, and public communications and outreach. The City has already
developed a storm water utility and user fee structure.
The City, however, did not have the necessary organizational structure and
programmatic resources in place to address the many issues involved in managing
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storm water quality. It determined that the proper way to address the whole range
of storm water issues was within a coordinated, comprehensive framework. Among
the factors which influenced its decision to develop a comprehensive strategy were
the following:
commitments already made to implement the recently approved West
Eugene Wetlands Plan (see below), as well as how the new mandates
could be incorporated into this Plan
a new proposed plan, the Natural Resources Functional Plan, aimed at
protecting the city's riparian and waterways corridors; this plan calls for
the City's urban runoff management plan to address the relationship
between riparian habitat, water quality and flood conveyance
implementation of other goals and policies contained in the city's
general land use plan
The CSWMP encourages this multiple objectives approach to storm water
management, including flood control, water quality treatment, and natural resources
protection. In addition, it strengthens the existing ordinances and implementation
activities already in place.
Relation of the Wetlands Plan to Storm Water Plan
Amazon Creek is the central drainage feature of Eugene. The channelization of
Amazon Creek (completed in 1959) significantly altered the hydrologic and hydraulic
conditions of the area. Although flood control benefitted the community and
allowed agriculture, commercial, and residential development to spread westward in
the city, it also had the unfortunate effect of hydrologically isolating surrounding
wetlands. This isolation and the subsequent draining of wetlands resulted in
environmental degradation.
Consequently, wetland restoration is a high priority for the City of Eugene. It
proposes to begin this process through a demonstration project called the Lower
Amazon Creek Restoration Project which aims to restore the hydrologic interchange
with surrounding wetlands/and restore fish and wildlife-habitat; and other associated
water resource values. This will be accomplished through the removal of levees, in
whole or in part: through modifying culverts; and through breaching levees at
selected locations.
In addition to restoration of historic wetlands, the city is developing a program to use
constructed wetlands for storm water quality treatment. The City is interested in
using these constructed wetlands to control (pre-treat) pollutants in urban runoff
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which enters a natural wetland system in West Eugene.
This idea grew out of the preparation and planning to develop the West Eugene
Wetlands Plan (WEWP), with the goal being the preservation of the natural system
through the pre-treatment of runoff from areas of the City. Without such treatment,
the degradation of the remaining existing natural wetlands would be a virtual
certainty. Storm water management is seen as critical to the success of the WEWP,
and to the survival of the wetlands themselves.
The use of constructed wetlands as a treatment process for urban runoff is emerging
as an alternative to conventional processes. Some of the advantages to using
constructed wetlands to temporarily store or treat storm water include:
water quality improvement
flood, erosion and storm damage reduction
replenishing surface and ground water supply
provision of fish and wildlife habitat
aesthetic or amenity benefit27
Regulatory Issues
There are numerous Federal laws and regulations, executive orders, as well as
comparable state and local regulations and ordinances which regulate activity in
wetlands or potential wetland areas. Current Federal policy forbids the use or
modification of natural wetlands to treat storm water.
Nevertheless, the following points should be borne in mind:
wetlands are functionally part of many municipal separate storm sewers
wetlands in urban areas may be dependent on storm water for their
very existence
Therefore, the strict application of regulations which forbid the degradation of
wetlands can have unintended consequences in watershed and wetland planning.
The City of Eugene experience suggests that flexibility should be allowed when
determining the level of appropriate protection for wetlands and that this can be
accomplished through a planning process which involves the local community as
well as Federal and state agencies which regulate these resources.
"City of Eugene, OR. Conceptual Engineering Design for
Water Quality Workshop. Final Report. Department of Public
Works, City of Eugene, OR, undated.
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Eugene's Existing Storm Water Program
The City's current storm water system has historically been focused on providing
flood control services. With its emphasis on storm water conveyance and flood
control, the existing program was in conflict with Federal mandates for water quality
management. Since the natural water quality treatment systems, such as riparian
areas, waterway corridors and wetlands have been extensively replaced with
conventional, structural conveyance facilities, ways need to be found to not only stem
the removal of natural systems, but seek opportunities to preserve them. The
CSWMP recognizes this goal and integrates it into the plan.
The City is faced with significant and complex issues as it seeks to transform its
existing storm water management program to meet the challenge of complying with
Federal mandates and heightened citizens' expectations. The framework of the
CSWMP will allow it to do this within a comprehensive planning context.
The City already has a dedicated revenue source to fund general and storm sewer
capital projects, the storm water utility user fee. It is the major revenue source for
the existing program, and is expected to be the principal revenue source for the new,
expanded program. The City has reviewed and analyzed current policy in light of
evolving Federal water quality mandates, and has refined its policy to include the
following:
that all users of the storm water system contribute to the financing of
the program
that property owners be encouraged to incorporate practices beyond the
minimum required through the use of financial incentives such as fee
reductions, etc.
Retrofitting and Eugene's Storm Water Management Plan
Eugene's CSWMP contains a specific capital facilities best management practice
(BMP) for retrofitting existing facilities, where feasible and appropriate, to achieve
water quality goals. These retrofits may include the installation of in-line sediment
'traps, detention/infiltration facilities, wetlands or riparian (re)vegtation, or simply
the modification of flood control facilities (i.e., storm drain inlets, retention basins, of
drainage channels) to function as water quality facilities.
Additionally, the capital facility BMP directly addresses the NPDES requirement that
the City assess the existing drainage and flood control facilities in order to determine
if retrofitting them would improve water quality.
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The capital facilities program includes retrofitting as one of the major activities
scheduled during the five-year start-up phase of the City's comprehensive storm
water management program, with retrofit implementation commencing around 1996.
The activities conducted as part of the retrofitting component of the Plan, include:
preparing a master list of existing facilities with relevant retrofit
considerations for each type
conducting an inventory of existing flood control facilities that will
provide information necessary to determine whether retrofits of these
facilities are feasible or not
reviewing inventory results to select sites and facilities where retrofits
would be most appropriate
developing a preliminary plan for retrofitting, with a schedule and
estimated costs
developing funding plans for retrofits
Eugene's Public Outreach Effort
An important feature in the evolution of the City's program are the numerous
methods for disseminating information about the development of the storm water
management program. These methods range from neighborhood newspapers such as
the Eugene Storm Water Connections, with general information about the City's
storm water management program, to more targeted information sheets, brochures,
and stickers, to community workshops to introduce citizens to storm water pollution
issues.
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Important Elements in Eugene's Program
The importance of the West Eugene wetlands to the overall stormwater
management plan.
the integration of natural resource elements into the overall
stormwater management framework and looking at the watershed
and how it functions as an integrated unit
. The significance of the multiple objective planning approach and why it could
be a model.
opportunity to address urban runoff issues from a comprehensive
perspective, including wildlife habitat, recreation, resource
conservation education, etc.
The high level and quality of citizen involvement and how this reduces conflict.
widespread citizen involvement with two-way communication
and feedback mechanisms facilitates consensus decision-making
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For more Information...
For more information about the City of Eugene's storm water program, contact the
Storm Water Program Coordinator at (503) 683-6839.
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City of Portland
Introduction
The City of Portland, Oregon, has developed innovative and comprehensive urban
runoff control strategies to meet the water quality requirements of Federal and state
legislation. Its program encompasses a wide range of activities for controlling both
point and nonpoint source pollution. The range of activities alone - from
transportation improvements to improved pesticides management - serves to
illustrate the diffuse nature of nonpoint source pollution.
Portland's storm water management program has been designed to be a constantly
evolving program which implements the management practices that succeed,
modifies or eliminates those that do not, and seeks to develop the most efficient and
productive practices throughout the program's life. Based on a. balanced economic
and environmental approach, its goal is to develop and implement the most
successful municipal storm water permit program in the Pacific Northwest.
Storm Water Permit Program (NPDES) Activities
The City of Portland, whose total population is roughly 450,000, has been classified as
a medium-size municipality for the purposes of the NPDES storm water permitting
program because less than 250,000 people are served by its municipal separate storm
sewer system. A significant portion of the city is served by combined storm and
' sanitary sewers, which are subject to other Clean Water Act regulations.
Under Oregon state-wide land use planning law, each city must define an urban
growth boundary (UGB) within which urban development is confined. Once
approved, they have the force of law. Within Portland's urban growth boundary, six
other agencies operate "municipal-like" separate storm water conveyance systems.
Together with the City, the six have become co-applicants for the Portland NPDhb
storm water permit application. The co-applicants include Multnomah County,
Multnomah Drainage District #1, Peninsula Drainage Districts #1 and #2, the Port of
Portland, and the Oregon Department of Transportation.
Although the permit has not yet been issued, the seven co-applicants are currently
conducting a number of programs and practices that directly or indirectly improve
the quality of storm water. While the NPDES permit application is a joint effort of all
the co-applicants, each co-applicant has responsibility for implementation of their
individual storm water management plan.
Significantly, from an institutional point of view, the City's NPDES program
implementation schedule has been developed to coincide with the majority of the co-
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applicants' fiscal year budget schedules. The goal of this action is ease of
implementation, but it also represents a concrete and very sensible method for
facilitating institutional cooperation.
NPDES Program Implementation Strategy
Portland's NPDES program strategy is to build on a foundation of existing urban
runoff control practices. The City developed.existing management program (EMP)
fact sheets corresponding to each regulatory requirement. Portland's proposed
NPDES management program emphasizes and builds upon existing storm water
controls and management practices. The program intends to limit the introduction of
new practices as much as possible, but where appropriate it will phase in new
practices during the life of the permit.
However, BMPs were developed to meet NPDES requirements not covered by
existing programs. The co-applicants have grouped .BMPs into implementation
categories:
public education and involvement
operations and maintenance procedures
industrial and commercial controls
illicit discharge controls
new development standards
structural controls
planning/system preservation and development
Nonpoint Source Program Activities - Some Examples
1. Used Oil Recycling Program
The City has a comprehensive solid waste and recycling program, which includes
used oil curbside pickup that properly recycles used oil. Although many
jurisdictions maintain used oil recycling programs, few offer pickup of used motor oil
as in Portland. (The City also provides yard debris, cardboard, paper, newspaper,
and metals residential curbside pickup.)
2. "Skinny Streets" Program
The City Office of Transportation has implemented new design standards for certain
street categories in an attempt to reduce environmental impacts, such as minimizing
the impervious area of new streets and preserving existing vegetation.
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3.
Snow and Ice Control
Sand and gravel materials are used at varying levels and picked up as soon as
possible after a storm has passed, which may take a few days or several weeks. By
comparison, many jurisdictions remove these materials only after the winter has
passed, if they collect them at all.
4. Pesticide/Herbicide Application
All applicators participate in an Integrated Pest Management (IPM) training program.
In addition, the City Planning Bureau has landscape requirements which reduce the
need for pesticides, herbicides, and fertilizer through the use of native plantings.
They are also developing an environmental seed mix.
Approach to Institutional Issues
The process by which the Portland NPDES permit co-applicants put together their
storm water permit application reveals some of the institutional issues which impact
upon the ability of a jurisdiction to carry out effective storm water management. The
seven jurisdictions have different institutional motivations and agendas and degrees
of political accountability and these factors affect how they approach and deal with
the problem of urban runoff management and control.
For example, the Oregon Department of Transportation (ODOT), one of the seven co-
applicants in the permit process, has as its mission the building of roads, not
managing storm water. Nevertheless, the ODOT maintains hundreds of miles of
storm sewer pipes that collect and transport storm water surface runoff, in addition
to open ditches and dry wells. It also has responsibility for 14 major storm sewer
outfalls in Portland.
The ODOT, however, is not subject to the same direct political pressures to pursue its
storm water management goals as, for instance, the City of Portland. The same holds
for the special drainage districts, the Port of Portland and other co-applicants. This
presents the potential for different outcomes. Such a divergence of institutional
interests and objectives could potentially limit the effectiveness of the storm water
management program.
However, the Portland experience illustrates how potentially problematic institutional
issues can be dealt with early in the program planning process and the result is likely
to be a more effective urban runoff control program. In the process of developing
the storm water management plan, the City's consultants worked with all the co-
applicants to define and clarify issues related to their proposed BMPs. As part of this
process they considered:
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the department or division within the agency which would be aftected
by or involved with the implementation of the BMP;
the agency's existing conditions related to the BMP, and the tasks
necessary to implement it;
the degree to which the implementation of the BMP is likely to affect
existing staff and/or resources
The fact that the process used in Portland considers these sometimes subtle but
important institutional concerns increases the probability of a successful outcome. It
also points up the importance of "issue scoping" and framework development to
ensure program effectiveness.
Program Funding
The City finances its storm water management activities through the levy of a
drainage fee which is based on the amount of runoff allowed to flow into the storm
sewer system. In 1992, the City initiated a storm water drainage discount program.
Discounts in the drainage fee are given to propoerty owners who limit the quantity
of storm water discharged from their property. The discount may be as high as one
hundred percent.
Discounts for water quality are not cuurently included in this program, but the City
code permits the imposition of such a fee and discount program in the future. The
existing discount program is directed at sites with on-site disposal systems.
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BMP Selection and Screening Factors used in Portland's Planning Process
Life Cycle Costs - The approximate cost of initial implementation
and future operation.
Regulatory Requirements - Does it meet existing and anticipated
Federal, state and local regulations? 4 ,
Pollutants - Does it offer reasonable control of the targeted
pollutants?
Implementability - Is it likely to be accepted and funded by the
various public agencies, city departments, and the general public?
Reliability - Does the BMP function predictably and is it effective
over time?
Environmental Impact - Consider the environmental impacts and
benefits of the BMP.
Equitability - How are the costs and benefits of the BMP
distributed?
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Portland's proposed NPDES stormwater management plan is innovative and
has the following components:
It emphasizes non-structural source controls including education
and maintenance programs.
It builds upon existing programs such as curbside recycling,
household hazardous waste collection, etc.
If encourages regional efforts and programs.
It emphasizes cooperation among its NPDES co-applicants to
improve water quality.
It phases in management plans to allow for budgetary and
resource constraints.
Portland's NPDES program highlights
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Portland's Compliance Strategies
Consider urban runoff issues as permanent issues which require a
long-term planning approach.
Share information and ideas and look for opportunities to cooperate
on projects, or share costs with other jurisdictions, etc.
Work closely with regulatory personnel throughout permit period
to discern their objectives, priorities and intentions.
Be creative and proactive in complying with permit and regulatory
requirements.
For more information...
For more information about Portland's urban runoff management program, please
call the Bureau of Environmental Services at (503) 823-7236.
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Glossary
Best Management Practice (BMP): A
practice or combination of practices that
are determined to be the most effective
and practical (including technological,
economic, and institutional
considerations) means of controlling
point and nonpoint pollutant levels
compatible with environmental quality
goals.
Constructed urban runoff wetlands:
Those wetlands that are intentionally created on sites that are not wetlands for the
primary purpose of wastewater or urban runoff treatment and are managed as such.
Constructed wetlands are normally considered as part of the urban runoff collection
and treatment system.
Drainage Basin: A geographic and hydrologic sub-unit of a watershed.
End of Pipe Control: Water quality control technologies suited for the control of
existing urban storm water at the point of storm sewer discharge to a stream. Due to
typical space constraints, these technologies are usually designed to provide water
quality control rather than quantity control.
First Flush: The delivery of a disproportionately large load of pollutants during the
early part of storms due to rapid runoff of accumulated pollutants. The first flush of
runoff has been defined several ways (e.g., one-half inch per impervious acre).
Impervious cover cap: A mechanism which establishes a Maximum Sustainable
Removal Rate for storm water control measures at 90%. The City of Austin, Texas
has incorporated this concept into its Land Development Code. It is designed to
avoid over-reliance on storm water control measures and recognizes their inherent
limitations and risk of failure due to lack of maintenance.
Impervious surface: A hard surface area that either prevents or retards the entry of
water into the soil mantle as under natural conditions prior to development and/or a
hard surface area that causes water to run off the surface in greater quantities or at
an increased rate of flow from the flow present under natural conditions prior to
development. Common impervious surfaces include walkways, driveways, parking
lots, concrete or asphalt paving, etc.
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Municipal separate storm sewer systems: Any conveyance or system of conveyances
*
^teJ^^vemment entity, is used for collecting .or conveymg storm water,
and is not part of a publicly-owned treatment works (POTW).
NPDES: National Pollutant Discharge Elimination System, created by Section 402 of
the Clean Water Act.
Post-development peak runoff: Maximum instantaneous rate of flow during a
storm, after development is complete.
ofan oTder urban runoff management structure, or a combinauon of mrprovement
and new construction.
Ultra-urban: Non-conventional BMPs that are particularly suited for use in highly
urbanized areas; based on sand filter technology
Urban runoff: That portion of precipitation that does not naturally percolate into the
ground or evaporate, but flows via overland flow.
Watershed- A drainage area or basin in which all land and water areas drain or flow
toward a central collector such as a stream, river, or lake at a lower elevation. The
land area that drains into a receiving waterbody.
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Bibliography
Anacostia Watershed Restoration Committee, The State of the Anacostia - 1989 Status
Report. Metropolitan Washington Council of Governments, 1989.
City of Alexandria, VA. AWandria Supplement to the Northern Virginia BMP
Handbook. Prepared by the Department of Transportation and Environmental
Services. Adopted February, 1992.
City of Austin, TX. "The First Flush of Runoff and Its Effects on Control Structure
Design." Environmental Resource Management Division, June 1990.
Citv of Austin, TX. "Storm Water Pollutant Loading Characteristics for Various Land
Uses in the Austin Area." Environmental Resource Management Division, March
1990.
City of Austin, TX. "Removal Efficiencies of Storm Water Control Structures. Final
Report." Environmental Resource Management Division, May 1990.
City of Eugene, OR. Conceptual Engineering Design for Water Quality Workshop.
Final Report. (Undated)
Dav Garv E, and C. Scott Crafton, Site and Community Design Guidelines for Storm
Water Management. Virginia Polytechnic Institute and State University, Blacksburg,
VA, 1978. - '
Bell, Warren, "A Catalog of Storm Water Quality Best Management Practices for
Ultra-Urban Watersheds." Presented at the National Conference on Urban Runott
Management in Chicago, IL on April 2,1993.
Buzzards Bay Project, "Bay Watch" (Newsletter), Spring/Summer 1993 Volume 7(5).
Dyer, Riddle, Mills & Precourt, Preliminary Engineering Report: Packed Bed Filter.
Prepared for the City of Orlando, FL. April 1991.
County of Fairfax, VA. Draft. National Pollutant Discharge Elimination System.
Municipal Storm Water Discharge Permit Application. Part 2. November 1992.
County of Fairfax, VA. Policy Plan: THP Countvwidp Policy Element of thq
Comprehensive Plan for Fairfax Countyr Virginia. 1990 Edition. Adopted by the
Board of Supervisors, August 6,1990.
Finnemore, EJ. and W.G. Lynard, "Management and control technology for urban
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3rm water pollution," in WaterPollntion Control FederationJournal. Volume 5*7),
Iyl982.
egulation, Tallahassee, FL
ower Colorado River Authority, T PR A 1 xfce Travis Nonpoint Source Pollution
f.mrnl Ordinar - Tarhni<-al Manual January 1991.
^'
Mew York: 1989)
G 1992 watorsh,.d Restorer, Source Book. Metropolitan Washington
' Governments, Department of tomronmental Programs, Washington, DC
As.es.ment nf TTrim
NOAA/USEPA rnagta] Nonpoint pmintinn Control Pro^m: Program Development
Gul^nce. National Oceanic and Atmospheric Administration/ U.S.
p .
Environmental Protection Agency, January 1993.
Novotny, Vladimir, and Gordon Chesters, H.nrtbnn
otny, Vlamr, an oron , .
Management. (New York: Van Nostrand Remhold Company, 1981)
Parrish John H and Stephen Stecher, "Nonpoint Source Pollution Control in the City
of Austin "City of Austin, TX, Environmental and Conservation Serves
Department, March 1991.
Council of Governments, 1992.
Schueler, Thomas R., "Hydrocarbon Hotspots in .
Controlled?" in Watershed Pro^rtinn Techniques. Volume 1(1), February
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Document No.
, 1990.
Vannouth (MAX Town o, "Effects of^ute 69J Drainage Irnproven^ents on
Water Quality in Bass River," November 11, 1992.
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