Developing Successful Runoff Control Programs For Urbanized Areas
Click HERE for graphic.
Developing Successful Runoff Control Programs for Urbanized Areas
Prepared by:
Northern Virginia Soil and Water Conservation District
Fairfax, Virginia
in 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
TABLE OF CONTENTS
ACKNOWLEDGEMENTS. . . . . . . . . . . . . . . . . . . . . . . . .ii
EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . 1
DEFINING THE PROBLEM OF URBAN RUNOFF MANAGEMENT . . . . . . . . . 4
Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
Purpose and Intended Audience of this Manual . . . . . . . . 4
Brief History of Runoff Control. . . . . . . . . . . . . . . 5
How Urban Runoff Adversely Affects Water Resources . . . . . 7
The Need for Urban Runoff Management . . . . . . . . . . . . 7
Retrofitting Developed Areas . . . . . . . . . . . . . . . .10
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 . . . . . . . . .21
Assessing Institutional Resources
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. . . . . . . . . . . . . . . . .37
City of Alexandria, Virginia . . . . . . . . . . . . . . . .38
Southeastern Massachusetts . . . . . . . . . . . . . . . . .42
City of Austin, Texas. . . . . . . . . . . . . . . . . . . .51
City of Orlando, Florida . . . . . . . . . . . . . . . . . .63
County of Fairfax, Virginia. . . . . . . . . . . . . . . . .71
Cities of Eugene and Portland, Oregon. . . . . . . . . . . .76
GLOSSARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
BIBLIOGRAPHY. . . . . . . . . . . . . . . . . . . . . . . . . . .92
i
ACKNOWLEDGEMENTS
This report was researched and written by Robert losco, Urban Water
Quality Specialist, Northern Virginia Soil and Water Conservation
District (NVSWCD), Fairfax, Virginia.
The author would particularly like to acknowledge the contributions
of Jean R. Packard, Vice-Chairman and Director, NVSWCD, and Norman
T. Jeffries, former Executive Director, NVSWCD. They reviewed many
drafts and provided valuable insights. 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
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
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
1
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
2
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
3
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
implementation. 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
4
districts, and other agencies concerned with land use, development,
and urban runoff 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
___________________________
1Murray, 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.
5
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.
6
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.
Click HERE for graphic.
The negative impacts of urbanization on water quality has been
well-documented in a number of sources, including the Nationwide
Urban Runoff Program 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 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.
7
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.
8
Why worry about urban runoff?
What is the problem with urban runoff anyway?
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.
9
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.
Click HERE for graphic.
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.
Retrofitting is a process that involves the modification of
existing surface @vater 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
10
may be appropriate for retrofits because they do not limit land
usage. Sand inters, 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.4
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 Government's 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 (NTDES) 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.
Click HERE for graphic.
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.
___________________________
4Schueler, Thomas R., "Hydrocarbon Hotspots in the Urban
Landscape: Can They Be Controlled?" in Watershed Protection
Techniques. volume l(l), February 1994, p. 3-5.
11
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 Sone Act Reauthorization jAmendments of 1990 (CZRA) 6217
- mandated state coastal program affecting coastal water quality
and required the development if 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 management programs which
resulted in state nonpoint source management programs to
control nonpoint sources of water pollution and protect
groundwater
Clean Water Act 320: 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
12
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 programs to improve water
quality. However, communities need to refer to applicable state
and Federal regulations to assure that they are in compliance with
all regulatory requirements.
Click HERE for graphic.
For example, some communities are not subject to NPDES permit
requirements but may be subject to requirements under the Coastal
Zone Act Reauthorization Amendments of 1990 ("CZARA"), and vice
versa. In addition, some states have additional regulatory
programs that may govern the management of storm water or runoff in
the absence of Federal requirements. Other communities may not be
subject to 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.
13
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 B.MP 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,
P. 59.
14
Click HERE for graphic.
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
15
- 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 stems 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]
16
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.
Surface sand 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-line facility,
processing all runoff leaving the site up to the point where the
overflow limit is reached. It consists of two parallel concrete
trenches, one for sedimentation, the other for filtration. A major
advantage of this filter design is that it requires a depth of 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.
Peat/sand filtration Systems Peat/sand filters are filtration
systems which were first 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
runoff quality management. A peat/sand filter system should be
considered for use on developments of several acres where the
pollutant removal requirement is higher than could be expected to
be achieved through the use of other ultra-urban BMP--;. 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 Public Rights-of-Way
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.
17
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.
___________________________
7 More detailed information on the retrofit capability of
these practices can be found in A Current Assessment of Urban Best
Management Practices. [see Bibliography]
18
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 t his 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.
19
Important Elements for Program Success
- Technical Capability
- Design Criteria for Selection of Appropriate Technology
- Implementation Authority/Enabling Legislation Dedicated
Funding Mechanism
- 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
20
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 0 & 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.
21
How can communities develop a successful program?
Each local government may have 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
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 your goals.
Pick the right people and the right organizations. The experience
gained from the case studies proves that 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.
22
Click HERE for graphic.
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 key 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.
23
Click HERE for graphic.
- 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 impairments Remember that not all
organizations a 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.
24
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?
25
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, viz., 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
26
- 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.
27
Click HERE for graphic.
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 of 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.
Click HERE for graphic.
Public education is an essential tool for using 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
28
Click HERE for graphic.
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.]
29
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 commitment 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 # EPA/625/4-191/027.
30
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:
Click HERE for graphic.
Local governments with strong institutional frameworks have led the
way in the development of utilities specifically designed to abate
NPS pollution or targeted at a particular type of NPS 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)
31
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.
- Check-off 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.
32
- 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.
33
Click HERE for graphic.
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.
34
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.
35
- Supervise, even direct if necessary, the construction phase of
all projects.
- Educate developers, consultants, contractors, politicians and
the general public about urban nonpoint source pollution
issues.
- Identify opportunities for public/private partnerships to
conduct nonpoint source pollution control activities.
36
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.
City 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
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 BMP's 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
39
parking garages, allowing full economic use of the surface areas.
Cost
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 Stormwater Quality Best
Management Practices for Ultra-Urban Watersheds. Presented at the
National Conference on Urban Runoff Management in Chicago, IL on
April 2, 1993.
10 Ibid.
40
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.
41
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 NPS 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
lbs. 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
42
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 storm 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.
43
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 close 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 Nonpoint 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
44
conventional storm drain system.) Several individual leaching
chambers were places 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 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.
45
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 Service 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.
46
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 $88,450
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
47
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.
48
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 Cage Cod Commission
The Cape Cod Commission works with towns on Cape Cod on various
matters
49
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 tries 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 of 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.
50
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
51
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.
52
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.
53
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.
54
creek watersheds were significantly higher than those from small
Suburban sites.16
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 USS)
- 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.
___________________________
16 City of Austin, Environmental Resource Management
Division, "Stormwater Pollutant Loading Characteristics for Various
Land Uses in the Austin Area." March, 1990.
17 City of Austin, Environmental Resource Management
Division, "Removal Efficiencies of Stormwater Control Structures."
Final Report, May 1990, p. 16.
18 Personal communication with Les Tull, Engineer, City of
Austin, Texas, May 25, 1993.
55
Strategy
The Austin sand filter program was implemented in response to
regulatory 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 not 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 and
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.
56
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
___________________________
20 Parrish/Stecher, "Nonpoint Source Pollution Control in
the
,City of Austin," march 1991., p. 12
57
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.
___________________________
21 Parrish/Stecher, "Nonpoint Source Pollution Control in
the
City of Austin," p.6
58
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 is less expensive than trying to restore its from
nonpoint source pollution is much less expensive than trying to
restore 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 development.
There are significant costs throughout the institutional structure
related to control of nonpoint source pollution. Preventing NPS
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 NPS 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
___________________________
22 Parrish/Stecher, "Nonpoint Source Pollution Control in
the City of Austin," p.7
59
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.
60
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 Austins.
Governmental entitie
