v>EPA
United States
Environmental Protection
Agency
Case Studies Analyzing the Economic
Benefits of Low Impact Development and
Green Infrastructure Programs
i
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Case Studies Analyzing the Economic
Benefits of Low Impact Development and
Green Infrastructure Programs
U.S. Environmental Protection Agency
Office of Wetlands, Oceans and Watersheds
Nonpoint Source Control Branch (4503T)
1200 Pennsylvania Ave., NW
Washington, DC 20460
EPA 841 -R-13-004
August 2013
Cover Photos:
Top Left: Landscaped curb extension captures street runoff (City of San Diego Low Impact Development
Design Manual)
Bottom Left: Cisterns at the Pine Knoll Shores Aquarium in Atlantic Beach, NC (Jason Wright, Tetra Tech,
Inc.)
Right: Green roof in Philadelphia, PA (U.S. Environmental Protection Agency)
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
Acknowledgments
EPA gratefully acknowledges the pioneering efforts of the communities listed below and the
time and assistance these communities provided to enable the preparation of this document so
that their experiences might benefit communities at large:
Alachua County Environmental Protection Division, Gainesville, Florida
Capitol Region Watershed District, St. Paul, Minnesota
Charlotte-Mecklenburg Storm Water Services, City of Charlotte and Mecklenburg County, North
Carolina
Kane County, Illinois
City of Kirkland Department Public Works, Washington
City of Lenexa Department of Public Works, Kansas
Milwaukee Metropolitan Sewerage District, Wisconsin
New York City Mayor's Office of Long-Term Planning and Sustainability, New York
Philadelphia Water Department, Pennsylvania
City of Portland Environmental Services and Office of Sustainable Development, Oregon
Seattle Public Utilities, Washington
Los Angeles County Department of Public Works, California
Iowa Department of Economic Development, Des Moines, Iowa
Support for this document was provided to the U.S. Environmental Protection Agency by Stratus
Consulting, Inc., of Washington, DC, and Boulder, Colorado under contract GS-10F-0299K.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
Contents
Exhibits Hi
Acronyms and Abbreviations iv
1. Introduction 1
1.1 Objectives 1
1.2 Key Findings 2
1.3 How to Use This Report 2
2. Background 9
3. Approach 11
4. Overview of Case Study LID/GI Programs 12
5. Economic Analyses of LID/GI Programs 19
5.1 Types of Economic Analyses 19
5.2 Metrics for Costs and Benefits Analyzed by Case Study Entities 23
5.3 Summary of Case Study Analyses 24
6. Key Findings from the Case Study Economic Analyses 29
6.1 Factors Influencing the Selection of Economic Analysis Methods 29
6.2 Using Economic Analyses to Address Public Concerns and Gain
Stakeholder Support 29
6.3 Using Economic Studies to Optimize the Benefits of Infrastructure
Investments 31
6.4 LID/GI Can Cost Less than Grey Infrastructure Alone 32
6.5 LID/GI Approaches Result in Multiple Benefits 32
6.6 LID/GI Approaches Can Be Successfully Integrated into Capital
Improvement Programs 34
7. Lessons Learned 35
7.1 Track and Analyze LID/GI Capital and O&M Costs to Plan and Budget
Effective Programs 35
7.2 Build LID/GI O&M Activities into the Program Framework 36
7.3 Encourage Stakeholder Involvement and Education 36
7.4 Plan and Budget Additional Analysis to Evaluate LID/GI Programs and
Projects 38
Appendix: LID/GI Case Studies
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
Exhibits
Exhibit 1. Summary of analytical approaches used by three LID/GI case study agencies 3
Exhibit 2. Summary of the key characteristics of LID/GI case study entities 5
Exhibit 3. Examples of the potential environmental, financial, and social benefits of
LID/GI 9
Exhibit 4. LID/GI case study communities 11
Exhibits. Primary case study LID/GI program objectives 12
Exhibit 6. Case study LID/GI program elements 13
Exhibit 7. Economic analyses used by case study entities 20
Exhibit 8. Summary of cost and benefit metrics used by case study entities 23
Exhibit 9. Summary of LID/GI case studies 25
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
Acronyms and Abbreviations
ACF Alachua County Forever (Florida)
APSIP Arlington Pascal Stormwater Improvement Project
APWA American Public Works Association
BCA benefit-cost analysis
BBS Bureau of Environmental Services (Portland, OR)
BMP best management practice
CIP Capital Improvement Program
CNT Center for Neighborhood Technology
CRWD Capitol Region Watershed District (St. Paul area, MN)
CSO combined sewer overflow
CSS A combined sewer service area
EPA U.S. Environmental Protection Agency
GASB 34 Government Accounting Standards Board Statement 34
GI green infrastructure
GIS geographic information system
GSI green stormwater infrastructure
HBA Homebuilders Association
HOA homeowners' association
HVAC heating, ventilation, and air-conditioning
IDED Iowa Department of Economic Development
LACDPW Los Angeles County Department of Public Works
LEDC Lenexa Economic Development Council (City of Lenexa, KS)
LID low impact development
LID/GI low impact development and green infrastructure
MARC Mid-American Regional Council
MMSD Milwaukee Metropolitan Sewerage District
MODA multi-objective decision analysis
MS4 Municipal Separate Storm Sewer System
NDS natural drainage system
NOAA National Oceanic and Atmospheric Administration
NPDES National Pollutant Discharge Elimination System
NPV net present value
NRDC Natural Resources Defense Council
O&M operation and maintenance
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
PV present value
PWD Philadelphia Water Department
ROW right-of-way
SPU Seattle Public Utilities
SSSA separate sewer service area
SUSTAIN System for Urban Stormwater Treatment and Analysis Integration
TBL triple bottom line (in reference to full BCA)
TIP tax-increment financing
TP total phosphorus
TSS total suspended solids
WTP willingness to pay
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
1. Introduction
1.1 Objectives
This report was prepared to help utilities, state and municipal agencies, and other stormwater
professionals understand the potential benefits of their low impact development (LID) and green
infrastructure (GI) programs. The objectives are to highlight different evaluation methods that
have been successfully applied, and also to demonstrate cases where LID/GI has been shown to
be economically beneficial. The intent of this document is to promote the use of LID/GI, where
appropriate, to supplement grey
stormwater infrastructure.
To meet this objective, EPA developed
13 case studies of selected public entities
throughout the United States that have
conducted economic evaluations of their
LID/GI programs. Because it is important
to look beyond just one measure, such as
capital cost, in order to see a complete
picture of the economic benefits and costs
of LID/GI, a variety of analysis types are
presented in the case studies.
EPA selected 13 case studies to represent
various types of economic analyses and
LID/GI-based programs. The case studies
were selected to represent a variety of
analysis methods in different geographic
areas of the United States, for different
types of municipal programs. The case
studies highlight locations where LID/GI
applications, in combination with grey
infrastructure, were found to be
economically beneficial. In some cases
LID/GI might not be an appropriate
choice, but this document should help to
enable a more comprehensive assessment.
This document is intended to provide
stormwater professionals with useful
information and insights to draw upon in
their own planning and analysis efforts. It
Low impact development (LID) is a land
development approach that is intended to reduce
development related impacts on water resources
through the use of stormwater management
practices that infiltrate, evapotranspirate, or
harvest and use stormwater on the site where it
falls.
Green infrastructure (GI) for the purposes of this
report can be defined as the natural and man-
made landscapes and features that can be used to
manage runoff. Examples of natural green
infrastructure include forests, meadows and
floodplains. Examples of man-made green
infrastructure include green roofs, rain gardens
and rainwater cisterns.
For the purpose of this report the terms LID and
GI are used interchangeably even though
landscape architects refer to GI as the network of
open space nodes and corridor that provide
habitat for wildlife.
The term grey infrastructure in this document
refers to traditional stormwater management
systems that quickly dispose of stormwater, such
as pipes, pumps and lined ditches, or use of
detention ponds.
Pagel
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
is not intended to serve as specific guidance or to provide cost and benefit "rules of thumb" for
application to other locations. Nevertheless, many of the approaches and findings of the
communities in the case studies are applicable to communities in similar situations.
1.2 Key Findings
Although many entities have begun to implement LID and GI approaches for stormwater
management, research shows that a relatively small percentage of jurisdictions have conducted
economic analyses of their existing or proposed programs. This lack of program analysis is due
to many factors including uncertainties surrounding costs, operation and maintenance (O&M)
requirements, budgetary constraints, and difficulties associated with quantifying the benefits
provided by LID/GI.
Those entities that have begun to analyze their green infrastructure programs and practices in
order to ascertain the cost effectiveness of green infrastructure in comparison to grey
infrastructure or hybrid systems have used different types of economic analyses, depending upon
their objectives, resources, or other considerations. These analyses ranged in level of complexity,
and captured the costs and/or benefits of the programs in different ways. To illustrate this range
of analyses, Exhibit 1 presents information on the analytical approaches used by three case study
entities. Charlotte-Mecklenburg Storm Water Services conducted a cost-effectiveness analysis to
help prioritize its LID/GI alternatives to meet the specific objective of protecting a drinking
water reservoir. The Portland Bureau of Environmental Services focused its analysis on a single
best management practice (BMP), green roofs, to gain support from developers and building
owners. The Philadelphia Water Department (PWD) conducted a benefit-cost analysis (BCA) to
compare the benefits and costs of city-wide grey and grey/green stormwater management
alternatives. The PWD refer to their study as "triple-bottom-line" (TBL) analysis, a term that has
become recognized in municipal asset management to emphasize the financial-social-
environmental aspects of a complete benefit-cost analysis, rather than only the financial.
1.3 How to Use This Report
Stormwater professionals can use the information and resources provided in this report when
planning, implementing, and assessing their own LID/GI programs. The report provides a
starting framework that both illustrates how others have evaluated the costs and benefits of their
LID/GI projects and programs and suggests methods communities may want to investigate to get
started on their own community-specific analyses.
The main body of the report provides summary information on the types of economic analyses
conducted by the case study entities, as well as the key findings and lessons learned by each
entity as a result of implementing their green infrastructure programs. The 13 write-ups, which
are provided in the appendix, offer more detailed information about each entity's LID/GI
program, the role and type of economic analyses conducted, the specific analytical methods used,
the results of the analyses, and key challenges and lessons learned. The case studies also provide
additional written and Web-based resources related to each case study program.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Exhibit 1. Summary of analytical approaches used by three LID/GI case study agencies
Entity Charlotte-Mecklenburg Storm
Water Services, North
Carolina
Program Stream restoration and BMPs
are used to reduce impacts
of rapid development on
drinking water quality
Role of BMP project prioritization
economic through evaluation of
analysis alternatives
Type of Cost-effectiveness
analysis
Key
metrics
Results
Capital cost per pound of
sediment prevented from
entering stream
• For urban retrofits, stream
restoration is the most cost-
effective means of
controlling sediment
deposition into the
reservoir.
• Prioritization allows the
county to implement need-
based, rather than
opportunity-based, projects
Bureau of Environmental Services
Portland, Oregon
Ecoroofs program: The City of
Portland encourages the
construction of green roofs by
providing incentives to developers
and by requiring green roofs on new
city-owned facilities and roof
replacement projects.
• Determine if benefits exceed cost
• If so, use results to increase
implementation of ecoroofs in the
city
Benefit-cost analysis (BCA;
including TBL elements) of
hypothetical new commercial
building with 40,000-square-foot
roof
• Present value (PV) life-cycle
costs
• Avoided costs
• Environmental and social benefits
• Net present value (NPV) of
program to the public (e.g., public
stormwater system and the
environment)
• NPV of the program to
developers and building owners
• NPV to public and private
stakeholders combined
Construction of ecoroofs has:
• Immediate and long-term benefits
to the public
• Positive net benefits accrue to
building owners starting in year
20 for the assumed conditions
Philadelphia Water Department,
Pennsylvania
The Green City Clean Waters
Program aims to reduce
combined sewer overflows
(CSOs) and improve water
quality.
Demonstrate full range of
societal benefits of LID/GI to
regulators and the public
Benefit-cost analysis (referred to
as a TBL analysis by PWD)
• NPV life-cycle costs and
benefits of Gl and grey
approaches
• Quantified and monetized
social and environmental
benefits
LID/GI-based approaches
provide important
environmental and social
benefits that are generally not
provided by grey infrastructure
A LID/GI-based approach,
coupled with targeted grey
infrastructure, is the city's
preferred approach to
optimize net benefits
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Exhibit 2 provides a more comprehensive summary that covers all of the case studies in this
report. Exhibit 2 provides a key to help stormwater professionals identify case study entities that
have common drivers and program goals and is intended to enable users to quickly identify
communities that have begun to address common issues and ascertain how their experiences can
be applied to the user's program evaluation process.
The matrix enables users to select case study analyses based on the following factors:
> Objective or role of the economic analysis
> Program goals and objectives
> LID/GI program elements
> Type of economic analysis
> Geographic location
> Urban or rural location
> Population served.
An "X" in a cell indicates that the specified characteristic is directly associated with the case
entity's economic analysis. An "O" indicates that although the specified characteristic is
associated with the case study's LID/GI program, it is not an aspect of the program covered in
the economic analysis.
For example, let's say your primary purposes for evaluating your LID/GI program are to
prioritize program alternatives and build community support for the preferred alternative
indicated by the analysis. You can quickly refer to the Exhibit 2 matrix and identify the case
study entities that had similar objectives (i.e., see "Role of Economic Analysis" and "Potential
Usefulness of Economic Analysis Results"). If you need to obtain a better understanding of how
it may be possible to quantify and monetize the benefits of your program, you will likely want to
review the case studies with characteristics similar to your own. For example, if your utility is
located in a densely populated urban area where GI will require the retrofitting of existing
neighborhoods, it might be helpful to examine the case studies for urban entities.
It is important to note that the focus of this report is not to determine how to identify the most
appropriate type of economic analysis. The use of a specific technique or type of analysis
depends on a variety of factors. Factors to consider include, the objective of the economic
analysis, how you plan to use the results (e.g., to gain stakeholder support, alleviate public
concerns, or identify economically feasible solutions) and the budget available for conducting
the analysis. On the other hand, the type of LID/GI techniques and the land uses in which they
are applied do not seem to play a large role for the type of economic analysis conducted in these
case studies. For example, cost-effectiveness and benefit-cost analysis can be applied to LID/GI
programs in both rural and urban areas and across a variety of infrastructure types. Consequently,
the case study matrix should be used to glean ideas and examples and was not written to serve as
a "how-to" manual.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Exhibit 2. Summary of the key characteristics of LID/GI case study entities3
Case study characteristics
Role of economic analysis
Develop project options/strategies (5)
Prioritize projects (5)
Evaluate cost-effectiveness (5)
Demonstrate benefits (8)
Potential Usefulness of Economic Analysis Results
Inform future project development/selection (7)
Gain support for project (9)
Obtain funding for LID/GI approach(2)
Bring in outside partners (2)
Increase implementation of program activities (1)
Establish basis for program adoption/continuation (4)
Stated program goals/objectives
Meet Municipal Separate Storm Sewer System (MS4)
requirements/separate sewer concerns (4)
Reduce CSOs (5)
Reduce stormwater runoff (9)
Flood control (7)
Improve water quality (13)
Improve drinking water quality (1)
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Case study characteristics
Reduce erosion (4)
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Provide other environmental benefits (6)
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Program elements
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Fees and economic incentives (5)
Large-scale bioretention ponds (3)
Land acquisition/preserve open space (6)
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Case study characteristics
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
1. Introduction
Case study characteristics
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economic analysis.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
2. Background
2. Background
Managing stormwater runoff solely through traditional "grey" infrastructure systems can present
a variety of challenges, including high construction, maintenance, and repair costs; increasing
combined sewer overflow events; and the introduction of pollutants into source waters. These
problems are increased as population and development continue to increase and new challenges,
such as changing weather patterns, increasing energy costs, new environmental concerns, and
aging water infrastructure arise. As the complexity and magnitude of these issues increase, states,
cities, and water resource managers increasingly have recognized that a new, integrated approach
to stormwater management—one that focuses on sustainability and benefits for multiple
stakeholders—will be needed to help ensure that the nation can provide the quality and quantity
of water demanded in the future.
Exhibit 3. Examples of the potential environmental, financial, and social benefits of
LID/GI
Environmental benefits
- Improved water quality
- Improved air quality from trees
- Improved ground water recharge
- Energy savings from reduced air conditioning
- Reduced greenhouse gas emissions
- Reduced urban heat stress
- Reduced sewer overflow
Financial benefits
- Reduced construction costs compared with all-
grey infrastructure, or compared with upsizing
grey infrastructure for increased runoff
Other social benefits
- Improved aesthetics
- More urban greenways
- Increased public education on their role in
stormwater management
- Reduced flash flooding
- Green jobs
- Potential increase in economic development
from improved aesthetics
The use of LID/GI can result in a number of financial, environmental, and social benefits, as
illustrated in Exhibit 3. Communities throughout the United States are beginning to recognize
these benefits and have become increasingly interested in implementing LID/GI-based
approaches. However, because LID and GI have not yet been implemented on a wide scale, a
number of uncertainties surround the implementation of these approaches in comparison with
traditional or grey infrastructure. Adoption of LID/GI practices has been hindered by concerns
that implementing LID/GI programs will increase costs or not adequately protect property or the
environment. Findings from the case studies related to these concerns include the following:
> Perception: It is difficult to develop estimates for the capital costs and O&M costs
associated with LID/GI-based technologies because of the site-specific nature of LID/GI,
which is often based on soil, vegetation and other unique site factors. Some case study
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
2. Background
entities used pilot studies, developed locally focused design guides, and obtained assistance
from consultants or university extension services to adapt O&M techniques to their areas
and develop and track the costs of these techniques. Many case study entities successfully
estimated the capital costs of their LID programs and projects using similar approaches.
> Perception: There is uncertainty regarding the effectiveness ofLID/GI approaches
compared to traditional infrastructure, especially over the long term. As with estimating
maintenance needs, communities have initiated pilots to gain a comfort level with using
LID practices. By monitoring pilot- and full-scale installations, in addition to reviewing
available literature, entities can inform their expectations concerning the effectiveness and
the limitations of these practices.
> Perception: The up-front capital costs associated with LID/GI are often more than those
associated with traditional infrastructure. In some cases, entities found the capital costs
required for LID/GI approaches, or mixed green/grey approaches, to be less than the capital
costs required for traditional grey infrastructure. Furthermore, when life-cycle costs
(including capital, O&M, and replacement costs over time) are taken into account, cost
savings compared to traditional infrastructure can be even more significant. In addition,
communities are finding that even when the capital costs are higher—for example, in urban
areas with no land available for infiltration—the associated benefits that accrue from the
implementation of LID/GI practices often provide the value to justify adoption of these
practices. For example, Charlotte-Mecklenburg Water Services found that reforestation was
not the most "cost-effective" stormwater management alternative, but it was implemented
for the many benefits an urban forest provides in addition to stormwater management, e.g.,
aesthetics, shading and air pollution abatement.
> Perception: The monetization of environmental and social benefits is a relatively new field,
with few standardized approaches. Some communities have turned to simply listing the
benefits and assigning qualitative or quantitative rankings to establish an acknowledgment
of the value of the societal or environmental benefits associated with LID/GI. Although
estimating the monetary value of environmental or other social benefits can be difficult,
some communities are beginning to use well-established methods or emerging tools for
monetizing certain benefits (e.g., reduction in pollutant levels, increased property values,
using benefit calculators such as the U.S. Department of Agriculture Forest Service's
i-Tree program [ www.itreetools.org1).
This report provides examples of methods for evaluating the potential economic benefits of
LID/GI and attempts to address some of the concerns that the uncertainties of benefit analyses
are too complex to undertake. As development pressures increase and aging infrastructure needs
to be replaced or new infrastructure added, it is essential that agencies, utilities, and
municipalities begin to develop the capability to use the appropriate tools and analytical
framework to assess, compare and evaluate the various alternatives, both green and grey, to
determine the best solution for that community.
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3. Approach
3. Approach
To compile the case studies in this report, more than 45 communities with existing or planned
LID/GI-based programs were evaluated. The communities included in this review were
identified by web searches, information from recognized LID/GI sources, e.g., the
U.S. Environmental Protection Agency (EPA) GI and LID websites, interviews with EPA
representatives from each of the 10 EPA regions, and the research team's personal knowledge
and experience.
The 13 case study communities in Exhibit 4 were selected to represent various types of economic
analyses and LID/GI programs, as well as a broad geographic and demographic range.
The case studies were developed from interviews with a representative from each case study
community, as well as reports and data provided by each entity. Each case study contains
highlights of the community's LID/GI program; a description of the economic analysis that was
conducted; the methods, results, and outcomes of the economic analysis; and key lessons
learned. Examples of similar LID/GI programs and economic analyses, sources, and contacts are
also provided. More detailed case study information for each community is provided in the
appendix.
Exhibit 4. LID/GI case study communities
1. California: Sun Valley Watershed, Los Angeles County Department of Public Works (LACDPW)
2. Florida: Alachua County Environmental Protection Department and Public Works Department
3. Illinois: Kane County Facilities, Development, and Environmental Resources Department
4. Iowa: City of West Union and the Iowa Department of Economic Development (IDED)
5. Kansas: City of Lenexa Public Works Department, Watershed Division
6. Minnesota: Capitol Region Watershed District, St. Paul
7. New York: Mayor's Office of Long-term Planning and Sustainability, New York City
8. North Carolina: Charlotte-Mecklenburg Storm Water Services, Mecklenburg County, City of Charlotte
9. Oregon: Portland Bureau of Environmental Services (BES)
10. Pennsylvania: Philadelphia Water Department
11. Washington: The City of Kirkland Public Works Department
12. Washington: Seattle Public Utilities (SPU)
13. Wisconsin: Milwaukee Metropolitan Sewerage District (MMSD)
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4. Overview of Case Study LID/GI Programs
4. Overview of Case Study LID/GI Programs
The LID/GI projects and programs implemented by the case study entities vary significantly.
Exhibit 5 summarizes factors influencing the implementation of specific LID/GI practices based
on program needs and objectives.
Exhibit 5. Primary case study LID/GI program objectives
Meet EPA National Pollutant Discharge Elimination System (NPDES) permit for either combined sewers,
sanitary sewer overflows, or separate storm sewer systems.
Reduce combined sewer overflows (CSOs) to comply with consent decrees.
Reduce stormwater runoff and related pollutants.
Reduce localized flooding during small storm events.
Improve water quality in lakes, rivers, and streams.
Improve drinking water quality.
Reduce erosion and resulting property damage.
Protect aquatic habitats.
Increase infiltration to recharge ground water for water supply and maintenance of stream baseflow.
Provide recreational opportunities and increased public access to local water bodies.
Enhance aesthetics and quality of life.
Provide other environmental benefits.
Reduce cost of replacing aging infrastructure.
Reduce adverse impacts from growth and development.
A brief overview of each entity's LID/GI program is presented below. Each overview includes
the name of the case study and a description of the program objectives, components, and
economic analysis. Exhibit 6 summarizes the types of program elements implemented by the
case study entities. The economic analyses conducted by each case study entity are explored in
more detail in Section 5 which covers the Economic Analyses of LID/GI Programs.
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4. Overview of Case Study LID/GI Programs
Exhibit 6. Case study LID/GI program elements
LID development standards/ordinances/guidelines
- Stream setbacks
- Protection of priority natural resource areas
- Zoning requirements
- Design guidelines
Fees and economic incentives
- Drainage fees
- Systems development fees
- Green roof incentives
Large-scale bioretention areas (e.g., retention
ponds)
Land acquisition
Open space preservation and park development
Stream restoration
Reforestation/tree planting/urban forestry
Floodplain reconnection
Wetlands development
Underground infiltration trenches/storage
Green streets and alleys
Permeable pavement for streets, sidewalks, and
parking areas
Smaller-scale bioretention and infiltration
- Rain gardens
- Bioretention/bioinfiltration areas
- Bioswales
- Filter strips
- Depressional parking islands and road medians
Ecoroofs/green roofs
Blue roofs
Reduction of impervious surfaces
Rainwater harvesting
- Rain barrels
- Cisterns
- Disconnecting downspouts
Evaluating the Benefits of Green Infrastructure to Reduce Localized Flooding
(Sun Valley Watershed, Los Angeles County Department of Public Works, Los Angeles County
(LACDPW), California)
LACDPW developed a comprehensive LID-based program that offers a multipurpose
approach to stormwater management in the Sun Valley watershed. The program, which
was initiated with an extensive set of infiltration-based projects, was initially undertaken to
respond to localized flooding. It developed into a plan to integrate flood control,
stormwater pollution reduction, and water conservation efforts using infiltration and
stormwater recycling practices. The program also addresses other community needs, such
as improving recreational resources and wildlife habitat, and enhancing aesthetic amenities
in the watershed. Projects include large scale infiltration basins such as the Sun Valley Park
Project, constructed wetlands, tree plantings, development of parks and open space, and
storm drains systems designed to convey stormwater to the project areas. The LACDPW
conducted a benefit-cost analysis (BCA) that compared the capital, land, and O&M costs
with the environmental and social benefits of its stormwater management alternatives. The
results led the Department to select an integrated solution.
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4. Overview of Case Study LID/GI Programs
Preserving Suburban Lands to Improve Water Quality Provides a Good Return on
Investment for the Community
(Alachua County Environmental Protection Department and Public Works Department, Alachua
County, Florida)
Alachua County which is located within the Gainesville, FL metropolitan area, developed
its LID/GI-based program to help mitigate the impacts of historical land development and
prepare for the expected population and development growth related impacts on water
resources in the region. The county's program includes development standards that require
GI and incentives for the use of GI on private lands. The Alachua County Forever (ACF)
program is the keystone of the program. Through ACF, the county acquires, protects, and
manages environmentally significant lands in order to protect water resources, wildlife
habitat, and natural areas suitable for resource-based recreation. Alachua County conducted
a benefit-cost analysis (BCA) that compared the benefit of increased property values that
resulted from increases in open space against the decreased tax revenues lost from public
acquisition of private property under the management of the ACF program.
Finding that Environmentally Sensitive Land Development is also Fiscally Responsible
(Kane County, Illinois, Blackberry Creek Watershed)
Kane County, located just west of Chicago, initiated a number of programs to encourage
"conservation-based land development." Its goal was to reduce flooding and streambank
erosion, improve water quality, and enhance aquatic habitat in local streams and wetlands.
A key component of the county's program is adoption of an LID/GI county stormwater
ordinance (which applies to all new development within the county) and corresponding
LID/GI-based BMPs. The BMPs include a number of green stormwater infrastructure
(GSI) management practices, as well as site planning and development design approaches
that preserve existing natural areas and use naturalized drainage, retention of small storm
events, and detention for larger storms. The county successfully implemented several
naturalized detention basin and permeable pavement projects, narrow street designs,
demonstration projects at a local school, and cluster development. It conducted a fiscal
impact analysis of county revenues and expenditures under both conservation-based and
conventional alternatives.
Long-Term Cost Savings Plus Environmental and Social Benefits Envisioned in Rural
Green Streets Pilot Project
(West Union, Iowa)
In partnership with the Iowa Department of Economic Development, West Union
developed an integrated approach to community sustainability and livability through the
Iowa Green Streets Pilot Project, which includes incorporating LID/GI techniques into the
renovation of six downtown blocks. Primary objectives of the project include improving
citizen safety, replacing aging infrastructure, improving water quality and habitat in a
nearby trout stream, and reducing flooding in the downtown area. As part of the project
analysis, West Union compared the long-term ownership costs of a green street design with
those of a conventional design.
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4. Overview of Case Study LID/GI Programs
Demonstrating Cost Savings Associated with New LID/GI Development Standards
(Public Works Department, City ofLenexa, Kansas)
The objectives of Lenexa's LID-based program, Rain to Recreation, are (1) to reduce
flooding, (2) to improve water quality and habitat, and (3) to provide recreational
opportunities. The program consists of regulatory and non-regulatory approaches to
stormwater management. The non-regulatory measures include major capital projects
(e.g., lakes that serve as regional retention facilities), land acquisition, and stream
restoration projects, as well as Gl-based components such as green street improvements,
rain gardens, bioretention areas, and wetlands. The regulatory measures include LID-
oriented development standards for new development and an accompanying BMP manual,
protection of priority natural resource areas, and a stream setback ordinance. Lenexa
conducted a capital cost assessment that compared the capital costs of implementing LID
BMPs with the costs of traditional approaches for different types of development.
Realizing Cost Savings and Environmental Benefits by Using Green Stormwater
Infrastructure Retrofits
(Capitol Region Watershed District, Minnesota)
The highly developed nature of the Capitol Region Watershed District's (CRWD's) service
area leaves little flexibility for stormwater management. When CRWD evaluates BMPs, it
is primarily concerned with identifying areas to retrofit. Through its Arlington Pascal
Stormwater Improvement Project (APSIP), CRWD implemented LID techniques to reduce
localized flooding and improve water quality by reducing the amount of phosphorus,
bacteria, mercury, nutrients, polychlorinated biphenyls, and turbidity discharging into an
important recreational lake and the Mississippi River. APSIP consists of 18 LID-based
stormwater BMPs, including eight rain gardens, eight underground (under-street)
infiltration trenches, a large underground infiltration/storage facility, and a regional
stormwater pond, all in a 298-acre subwatershed. CRWD investigated the capital cost and
cost-effectiveness of different BMPs in terms of pollutant removal and flood control.
Bringing Together Agency Stakeholders to Assess the Cost-Effectiveness and Feasibility of
Sustainable Stormwater Management in Combined Sewer Overflow Areas
(Mayor's Office of Long-term Planning and Sustainability, New York City, New York)
New York City developed a sustainable stormwater management plan as part of the city's
broader sustainability initiative, PlaNYC. The overall water quality goal of PlaNYC is to
improve public access to (and recreational use of) the city's tributaries from 48 percent today
to 90 percent by 2030. Toward this end, the plan evaluates the feasibility of various policies
that, when fully implemented, will create a network of decentralized source controls to
detain or capture more than one billion additional gallons of stormwater annually. The plan
includes a variety of structural and nonstructural source control measures related to four
program areas: the public right-of-way, city-owned property, open space, and private
development. Structural source control measures include green roofs, blue roofs, rainwater
harvesting, vegetated controls, tree planting, permeable pavements, and engineered
wetlands. Nonstructural measures include design guidelines, performance measures, zoning
requirements, and economic incentives. The city conducted a cost-effectiveness analysis
comparing various LID runoff control options with traditional grey infrastructure options.
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4. Overview of Case Study LID/GI Programs
Using Cost-Effectiveness to Prioritize Projects that Reduce the Impacts of Rapid
Development that Impair a Drinking Water Reservoir
(Charlotte-Mecklenburg Storm Water Services, City of Charlotte and Mecklenburg County,
North Carolina)
The primary objective of Charlotte-Mecklenburg Storm Water Services' stormwater
program is to protect drinking water quality and water quality for recreation, aquatic
habitat, and endangered species. The biggest threat to water quality in the region is an
increased volume of stormwater runoff caused by rapid development; the runoff
contributes pollutants and sediment from stream erosion. The LID-related components of
the county's capital improvement program (CIP) include three focus areas: in-stream
restoration, upland LID-based retrofits (e.g., rain gardens, bioswales), and reforestation. In
addition, the Town of Huntersville (in Mecklenburg County) implemented a post-
construction LID-based ordinance to mitigate degradation of the drinking water reservoir
from future development. The county's incorporation of LID approaches was initiated
based on watershed modeling that had compared the effectiveness of alternative
stormwater management approaches with existing (traditional) practices at build-out
conditions. The model results indicated that LID was the only approach that would achieve
sufficient pollutant removal and prevent further degradation of the county's waterways.
Today, LID is being implemented in combination with conventional approaches designed
to manage larger storms.
A Benefit-Cost Analysis Provides the Basis for Incentivizing Ecoroof Construction
(Bureau of Environmental Services, Portland (BES), Oregon)
BES developed a stormwater management program that recognizes the need for sustainable
stormwater management systems throughout the city. The LID-based program helps the
city comply with its MS4 discharge permit, reduce CSO events, maintain water quality, and
control flooding. Specific program components include green roofs, green streets,
stormwater BMP monitoring, school BMPs, and a financing program. BES conducted a
BC A (including social, financial, and environmental elements) of a hypothetical green roof,
calculating the net present value (NPV) of the practices to illustrate the long-term value of
these investments to the public, developers, and building owners.
A Benefit-Cost Analysis of Combined Sewer Overflow Control Options
(Philadelphia Water Department (PWD), Philadelphia, Pennsylvania)
PWD is committed to the development of a balanced "Land-Water-Infrastructure"
approach to achieve its watershed management and CSO control goals. The PWD program
includes traditional grey infrastructure, as well as land-based LID/GI stormwater
management techniques and projects involving the physical reconstruction of aquatic
habitats. The LID/GI land-based approaches include disconnection of impervious cover,
bioretention, subsurface storage and infiltration, green roofs, swales, green streets
(including permeable pavement), and tree canopy. The water-based approaches include
streambed and bank stabilization and reconstruction, aquatic habitat creation, plunge pool
removal, improvement offish passage, and floodplain reconnection. The PWD conducted a
BCA analysis that demonstrated the full range of costs and social benefits of LID/GI to
regulators and the public. The PWD uses the term "Triple-Bottom-Line," a recently
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4. Overview of Case Study LID/GI Programs
adopted term used in municipal asset management to emphasize that a BCA includes social
and environmental considerations, as well as financial elements.
Ranking Benefits to Help Assess the Feasibility of LID Approaches in Capital
Improvement Program (CIP) Transportation Projects
(The City of Kirkland Public Works Department, Kirkland, Washington)
In 2007 stormwater engineering staff in the Kirkland Public Works Department began
investigating ways to integrate LID/GI into CIP transportation projects. Primary drivers
included the protection of Puget Sound and local waterways and the anticipation of future
NPDES MS4 permit requirements for LID/GI. In addition, analyses conducted in
surrounding municipalities showed that it was often more cost-effective to implement
LID/GI than more traditional approaches such as pipes and ponds. To identify
implementation opportunities, Kirkland stormwater staff evaluated the feasibility of
integrating LID/GI elements into 10 planned CIP projects. This evaluation helped them to
establish a process for integrating LID into CIP projects. Today, when technically feasible,
LID is integrated into the conceptual design phase of all projects involving public
right-of-ways.
Using an Asset Management Approach for Optimizing Green Stormwater Infrastructure
(GSI) Application
(Seattle Public Utilities (SPU), Seattle, Washington)
SPU became a leader in municipal water and wastewater asset management beginning in
2002 and applied these techniques to its advanced GSI program. The primary
environmental concerns facing SPU's drainage and sewer department include impairment
of Seattle's receiving waters and aquatic life and flooding of roadways and property due to
increasing runoff. SPU developed a comprehensive GSI program to address stormwater
management throughout the city. The program includes natural drainage system (NDS)
projects, which involve redesigning residential streets to take advantage of plants, trees,
and soils to clean runoff and manage stormwater flows; GSI for stormwater code
compliance; and Residential Rainwise, a public education and outreach program which was
designed to encourage residential customers to take steps to reduce the volume of
stormwater sent to public conveyance systems from private properties. SPU's asset
management process allows the utility to make decisions in a transparent manner, fully
informed by life cycle analyses and, where possible, BCA. SPU uses the term TBL in its
asset management program for costs and benefits analyses to highlight that a BCA includes
social, environmental, and financial considerations. The SPU case study describes a
business case study of one of its NDS projects, which was presented for asset management
review.
Optimizing the Potential for Green Infrastructure to Reduce Overflows and Provide
Multiple Benefits
(Milwaukee Metropolitan Sewerage District (MMSD), Milwaukee, Wisconsin)
LID/GI solutions are critical components of MMSD's plan to prevent water quality
degradation and flooding that can result from development and reduce CSOs. MMSD's
programs include Green Seams, which involves purchasing and preserving large areas of
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4. Overview of Case Study LID/GI Programs
land (that contain water-absorbing [hydric] soils) along waterways, and a very successful
rain barrel program. In addition, MMSD implemented several LID/GI demonstration
projects on both private and public lands. Going forward, the district will focus on
implementation of various LID/GI strategies such as the integration of LID/GI approaches
into its 2020 facilities planning effort. MMSD envisions that subsequent analyses will help
to further optimize the integration of LID/GI into its 2035 or 2040 facilities plans.
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5. Economic Analyses of LID/GI Programs
5. Economic Analyses of LID/GI Programs
Utilities and other implementing agencies are using numerous economic analysis techniques to
evaluate stormwater management alternatives. The following sections describe eight types of
economic analyses represented in the 13 case studies (Section 5.1); the benefits and costs
evaluated by the case study entities (Section 5.2); and a summary of each case study's economic
analysis, including the role and type of analysis used, key metrics, and outcomes (Section 5.3).
5.1 Types of Economic Analyses
Exhibit 7 lists the seven types economic analyses represented in the case studies and provides
examples of the key components of each analysis. More detailed descriptions are provided below
in the approximate order of complexity. The level of complexity increases as more metrics, e.g.,
capital costs, life-cycle costs, benefits and analytical methods, e.g., life-cycle costing, NPV,
monetizing benefits are included in the analysis.
Capital cost assessment. The simplest form of economic analysis, capital cost assessment can be
used to compare the up-front costs associated with both LID/GI and grey infrastructure
alternatives. Capital costs typically include costs incurred for the purchase of land, construction,
materials, and equipment used in the development of stormwater infrastructure, i.e., the total cost
of bringing a project to an operable status. Capital cost assessment does not incorporate O&M or
life-cycle costs and therefore does not always provide an appropriate comparison of alternatives
when the owner has a long-term financial interest. Unlike operating costs, capital costs are one-
time expenses, although payment can be spread out over many years in financial reports and tax
returns. The City of Lenexa, Kansas, used capital cost assessment to show savings associated
with LID/GI BMPs compared with traditional techniques.
Benefit-cost analysis. BCA is a common accounting framework used to evaluate the net effect of
a proposed program or project. Questions are posed such as: Do the benefits outweigh the costs?
Who benefits? Who incurs the costs?1 A BCA can be used to determine whether a proposed
project/program is a sound investment and used to determine how the costs and benefits compare
to other options. This type of assessment can include aspects such as avoided costs or
opportunity costs associated with the capital construction decision.
Alachua County, Florida, conducted a BCA of its LID/GI open space preservation program in
response to public concern over potential loss in property tax revenue associated with acquiring
open space for preservation. The county compared the cost of the reduction in property taxes
from the acquisition of open space against the benefits of increased property values and
1 Note that BCA is different from cost-effectiveness analysis. Cost-effectiveness analysis is used to determine
capital costs or life-cycle costs per unit of a single parameter, e.g., the cost per pound of pollutant removed,
whereas BCA is used to compare all monetized benefits to costs to derive an estimate of net monetized
benefits (or a benefit-cost ratio). A BCA should also qualitatively describe non-quantifiable benefits and costs.
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5. Economic Analyses of LID/GI Programs
Exhibit 7. Economic analyses used by case study entities
Type of economic analysis
Components of economic analysis
Capital cost assessment
Benefit-cost analysis (BCA)
Life-cycle cost and/or benefit
assessment component of BCA
Cost-effectiveness analysis
Fiscal impact analysis
Benefit valuation component of BCA
Quantitative ranking informed by
qualitative description of non-monetized
benefits and external costs
Up-front costs, e.g., land, construction, materials, equipment
One-time expenses (does not include O&M or financing costs)
Comparison of financial or monetized benefits to costs (NPV life-cycle
benefits and costs if possible)
Quantified and monetized financial, environmental, and social costs
and benefits (sometimes called "triple-bottom-line" in municipal asset
management programs)
Qualitative description of financial, environmental, and social benefits
(and costs) when quantification is not feasible
Life-cycle costs over the project life (sum of PV of investment costs,
capital costs, installation costs, O&M costs, replacement costs, and
disposal costs over project or program lifetime)
Life-cycle benefits over the project life (sum of PV of benefits over
project or program lifetime)
Life-cycle net benefits ,i.e., NPV
Capital or life-cycle costs as measured over comparative and uniform
time frame, e.g., the cost per pound of a specific pollutant removed per
year
Impact of development or land use change on the costs of
governmental units or services
Impact of development or land use change on revenues of
governmental units
Quantification of benefits in non-monetary terms, e.g., pounds of
pollutant removed, number of increased recreation visitor days
Monetization of benefits, e.g., avoided treatment costs, monetary value
of recreational user days
Qualitative description of benefits and costs
Quantitative ranking of benefits and costs, e.g., on a scale of 1 to 5
subsequent increased assessments for those properties located near the newly acquired open-
space areas.
Traditionally, BCAs have included benefits and costs that can easily be assigned a market value,
e.g., revenues and expenditures. BCAs using approaches that take into account the environmental
and social values associated with proposed programs in addition to the financial outcomes are
becoming more common. (To emphasize that an analysis does include social and environmental
considerations, as well as financial, some municipalities, including Seattle and Philadelphia,
have used the term triple-bottom-line (TBL) to refer to a comprehensive BCA.)
The comprehensive BCA approach reflects the fact that society and its enterprises—including
the institutions that work specifically in the public interest, such as water and wastewater
utilities—typically are engaged in activities intended to provide the greatest total value to the
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5. Economic Analyses of LID/GI Programs
communities they serve. These values extend beyond the traditional financial bottom line of a
standard financial analysis, which portrays only cash flows. Agencies that serve the public
interest also need to consider other responsibilities that do not directly show up in the financial
bottom line such as reducing urban heat stress and reducing risk to public safety associated with
localized flooding. Optimal program design thus accrues benefits across programs by identifying
and measuring how any one action or set of actions contributes to "social," "environmental" and
"fiscal" bottom lines.
A comprehensive BCA assesses the full range of internal and external costs and benefits of an
activity project or program, including nonmarket outcomes. It provides an organizing framework
within which the broad array of benefits and costs can be portrayed and communicated.
A BCA should include outcomes that can be quantified into physical units such as reduced tons
of carbon or increased recreational days, or monetized into dollar terms. The analyses should
also be conducted to include, as much as possible, outcomes that are less amenable to reliable
valuation and instead require qualitative discussion. To assign monetary values to social and
environmental outcomes, economists typically use surveys, inferences from market behavior, or
other modeling techniques.
The Los Angeles County Department of Public Works, the Portland Bureau of Environmental
Services, the Philadelphia Water Department, and the City of Kirkland, Washington, all include
comprehensive BCA components in their economic analyses, taking into account at least some
social and environmental costs and benefits associated with their respective programs and
projects. As described in the case studies, not all entities were able to quantify and/or monetize
benefits, and the level and depth of analyses varied across studies. For example, Portland BBS
monetized several environmental benefits that are not typically valued in traditional BCAs, i.e.,
the value of habitat creation and improved air quality. PWD quantified and monetized benefits
and costs across social, environmental, and financial lines, developing a comprehensive BCA of
proposed LID/GI program options.
Life-cycle cost or benefits assessment component of BCA. In economics, life-cycle costs are
defined as the sum of the present value (PV) of investment costs, capital costs, installation costs,
O&M costs, and replacement and disposal costs over the life of a project.2 Similarly, life-cycle
benefits represent the PV of the benefits of a project that accrue over its life. A comprehensive
BCA will include calculation of life-cycle net benefits, also referred to as the net present value
(NPV) of a project, which are the PV benefits minus PV costs. For a rural green street project,
West Union calculated the life-cycle cost savings associated with the use of permeable pavement
compared to the costs associated with using traditional pavement. The analysis showed that
although the permeable pavement would cost more up front, the city would realize savings
beginning in year 15 of the project due to reduced O&M costs compared with the cost of deicing
traditional pavement.
Life-cycle costs and benefits often serve as the basis for cost-effectiveness and benefit-cost
analyses (described below). For example, Seattle Public Utilities (SPU) used life-cycle costs to
conduct cost-effectiveness analysis of NDS project options. The results yielded life-cycle costs
per gallon of stormwater infiltrated, per greened acre, and per kilogram of total suspended solids
(TSS) removed. SPU considers its natural drainage infrastructure which includes the raingardens,
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5. Economic Analyses of LID/GI Programs
bioswales and green roofs it builds and maintains as part of its overall infrastructure and reports
this infrastructure on its basic financial statements in adherence to the Government Accounting
Standards Board Statement 34 (GASB 34) requirements for state and local governments. It
capitalizes its GSI assets in the same way as accounts for its traditional infrastructure, based on
the useful life of the asset and the typical replacement cycle. By reporting its GSI infrastructure
under GASB 34, SPU can show an increased value of its assets and equity, thereby supporting its
ability to fund expenditures from the capital budget. Reporting under GASB 34 also enables SPU
to capture the value of these GI assets in its financial reporting and makes the economic benefits
of GI more explicit when planning for future expenditures.
The Philadelphia Water Department's (PWD) BCA analysis of green and grey infrastructure
alternatives included an assessment of life-cycle benefits over a 40-year period. As part of this
analysis, PWD evaluated the city-wide benefits of specific GI practices, taking into account
planned implementation schedules over the life of the project, as well as the maturation of GI
components. For example, a tree will not provide as many benefits (such as shading and
paniculate interception and retention) the year it is planted as it will 20 years later, when it is
fully mature.
Cost-effectiveness analysis. Communities can use cost-effectiveness analysis to more directly
compare LID/GI and grey infrastructure solutions. This type of analysis is used to determine and
compare the capital costs or life-cycle costs per unit of a specific measure, e.g., stormwater
runoff reduction, pounds of pollutant removed. The Capitol Region Watershed District (CRWD)
in the St. Paul, Minnesota, area used cost-effectiveness analysis to determine the PV cost per
cubic foot of stormwater reduction associated with different LID/GI -based BMPs. CRWD also
determined the PV cost per pound of pollutant removal achieved. Mecklenburg County, New
York City, SPU, and MMSD also conducted cost-effectiveness analyses as part of their
economic evaluations of LID/GI.
Fiscal impact analysis. Fiscal impact analysis is used to estimate the impact of a development or
a land use change on the costs and revenues of governmental units. The analysis is generally
based on a community's fiscal characteristics, e.g., revenues, expenditures, land values and
characteristics of the development or land use change, e.g., type of land use, distance from
central facilities. The analysis enables local governments to estimate the difference between the
costs of providing services to a new development and the revenues—taxes and user fees, for
example—that will be generated by the development. Kane County, Illinois, used fiscal impact
analysis to compare the public costs (net revenues/costs) associated with LID/GI-based
development against the costs of traditional development practices.
Benefit valuation component of BCA. Several case study entities were interested in quantifying
the benefits provided by various alternatives or projects over time and did not necessarily need to
compare the benefits with program costs. Milwaukee's Metropolitan Sewerage District (MMSD)
evaluated the benefits (see below) of applying LID/GI practices throughout the city's combined
sewer service area. The benefits identified include increased property values, job creation,
reduced infrastructure costs, reduced pumping costs, increased recreational opportunities,
reduced stormwater volume and sediment loading, increased groundwater recharge, increased
carbon sequestration, and reduced energy use. MMSD believes that this analysis will help
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5. Economic Analyses of LID/GI Programs
MMSD employees, regulators, and the public to understand the multiple benefits of GI and move
it forward.
Quantitative ranking of a full range of benefits and costs. The first step in a BCA is to
determine an expected effect, such as a quantitative ranking, then design a study plan to
monetize the expected costs and benefits. Due to a number of factors such as limited resources
and insufficient data, it is not always feasible to quantify or monetize the benefits and costs
associated with a given project or program. In such cases, communities can qualitatively describe
the full range of benefits and costs and then conduct a quantitative analysis of the costs and
benefits based on a numeric scale that represents low to high, e.g., a scale of 1 to 5. Cost and
benefit categories also can be assigned a weighting factor based on individual agency objectives.
Using weighting factors allows the community to establish a framework for prioritizing/ranking
proposed program options. Kirkland, Washington, used this approach to evaluate the integration
of LID/GI practices into CIP transportation projects. As a result, the county established a process
for including LID/GI in all CIP transportation projects.
5.2 Metrics for Costs and Benefits Analyzed by Case
Study Entities
Exhibit 8 shows the various cost and benefit metrics quantified and/or monetized by the case
study entities. Benefits and costs that were qualitatively discussed are not included in Exhibit 8.
Exhibit 8. Summary of cost and benefit metrics used by case study entities
Cost-related metrics
Benefits metrics
Total costs can be presented in a number of ways:
• Capital costs
• O&M costs
• Life-cycle costs
• Annualized costs
• Cost per unit of stormwater volume reduction or
infiltration
• Cost per pound of total phosphorus, total nitrogen,
and/or TSS removed
• Cost per unit of peak flow reduction
• Cost per greened acre
• Cost of LID/GI techniques compared to grey or
traditional approaches
• Net public costs of LID-based development (costs
minus revenues)
• Cost of construction disruption based on amount
of extra time local residents will spend in
construction-related traffic
Avoided localized flood control facility costs
Avoided water quality treatment costs
Avoided grey infrastructure costs
Avoided social costs due to creation of "green" jobs
Energy savings due to reduced need for heating and
cooling, and associated value
Reduced carbon dioxide emissions due to energy savings
and carbon sequestration, and associated value
Change in property values
Avoided health costs due to improved air quality
Value of habitat provided by green roofs, based on the
cost of creating upland habitat in the local area
Reduction in heat-related fatalities, and associated value
Value of water quality and aquatic habitat improvements,
based on household willingness to pay, acres of wetlands
improved or created, and associated value of wetland
services
Increased recreational user days, and associated values
Water conservation benefits from groundwater recharge,
based on avoided imported water costs
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
5. Economic Analyses of LID/GI Programs
The cost metrics listed in the exhibit represent engineering cost estimates, i.e., capital, O&M,
life-cycle costs, as well as engineering estimates for specific performance measures used in cost-
effectiveness analysis, e.g., pounds of total phosphorus removed or gallons of stormwater
infiltrated. Many of the benefits listed in Exhibit 8 were quantified based on avoided costs
associated with implementing LID/GI solutions such as a reduced need for traditional localized
flood control infrastructure. Additional benefits were quantified based on willingness-to-pay
values from the literature, market prices, and other economic modeling techniques.
5.3 Summary of Case Study Analyses
Exhibit 9 provides a summary of the economic analyses conducted by each case study entity,
including the role and type of analysis, key metrics evaluated, and outcomes of the analysis. The
case studies are presented in approximate order based on level of complexity of the economic
analyses, from capital cost assessments to full BCA analyses that include social and
environmental costs and benefits, as well as financial.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
5. Economic Analyses of LID/GI Programs
Exhibit 9. Summary of LID/GI case studies
Entity
LID/GI program
description
Role of analysis
Type of
analysis
Key metrics
Outcome of analysis
Lenexa Public
Works Department,
KS
Charlotte-
Mecklenburg Storm
Water Services, NC
Capitol Region
Watershed District
(CRWD), MN
Adoption of LID/GI-oriented
development standards,
BMPs, and systems
development fees as part of
the Rain to Recreation
program.
Restoration of streams
damaged by runoff from
development, and BMPs to
reduce impacts of rapid
development, were assessed
to determine impacts on
drinking water quality.
Eighteen BMPs in a 298-
acre watershed designed to
reduce localized flooding and
stormwater runoff, improve
water quality, and enhance
recreation in local park.
Evaluate impacts of
development
standards and fee
Gain support from
developers prior to
adoption
Project prioritization
through evaluation
of alternatives
Capital cost
assessment
Cost-
effectiveness
Assess BMP
effectiveness for
pollutant removal and
flood control
Guide future project
development
Capital cost
assessment
Cost-
effectiveness
Capital cost savings from
implementation of BMPs
compared to traditional
development
Capital cost per pound of
sediment prevented from
entering stream and
downstream drinking water
reservoir
• Capital cost savings
• PV life-cycle costs
• PV cost/pound removal
of pollutants
• PV cost/cubic foot
stormwater reduction
Savings of tens to hundreds of
thousands of dollars in site work and
infrastructure costs with the application
of LID/GI BMPs for different types of
developments. In most cases, savings
more than offset costs associated with
the systems development fees.
Analysis helped to gain developer
support for standards and fee.
Analysis showed that stream
restoration is the most cost-effective
way to immediately control sediment in
this area. Consequently, stream
restoration is the focus of the county's
program. Prioritization allows the
county to implement need-based,
rather than opportunity-based,
projects.
Initial capital cost assessment found
substantial cost savings with Gl
compared with grey infrastructure. This
led to an analysis that helped CRWD
validate an LID/GI-based watershed
approach to water resource
management and increased
awareness of and support for Gl.
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The Economics of Low Impact Development and Green Infrastructure Programs
5. Economic Analyses of LID/GI Programs
Entity
LID/GI program
description
Role of analysis
Type of
analysis
Key metrics
Outcome of analysis
New York City
Mayor's Office of
Long-term Planning
and Sustainability,
NY
Seattle Public
Utilities (SPU), WA
West Union, IA
Kirkland Public
Works Department,
WA
Distributed Gl controls to
reduce stormwater runoff
and CSOs, improve water
quality, and increase public
access to tributaries,
compared to conventional
CSO controls such as
tunnels and basin storage.
Natural drainage system
(NDS) projects on residential
streets; LID/GI-based
stormwater regulations and
Residential Rainwise
Program to encourage
customers to reduce the
volume of stormwater sent
to the public system.
Pilot community for Iowa
Sustainable Green Streets
Initiative to replace aging
infrastructure and reduce
localized flooding in
downtown area.
Integration of LID/GI into
conceptual design phase of
all capital improvement
projects within public rights-
of-way.
Develop potential
stormwater strategies
Prioritize pilot projects
• Identify economically
feasible alternative
for NDS street project
• Integrate LID/GI into
SPU's asset
management program
to enhance financial
and public
accountability
• Gain support for
project
• Guide decision-
making
• Obtain funding
Establish process for
integrating LID/GI into
CIP transportation
projects
Cost- • PV life-cycle costs
effectiveness . py costs/gallon of runoff
captured
• Comparison of Gl to
grey infrastructure
Cost- • PV capital and O&M
effectiveness costs
• PV costs per greened
acre
• PV costs per kilogram
TSS removed
• PV cost per gallon of
stormwater infiltrated
• Life-cycle cost Cumulative life-cycle cost
analysis
• Benefit
valuation
(avoided
costs)
Quantitative
ranking of costs
and benefits
savings of permeable
pavement compared to
traditional
Cost- effectiveness
LID/GI demonstration
potential
Capital costs compared
to grey infrastructure
O&M costs
Collaboration potential
Environmental and
social benefits
Cost savings with Gl compared to grey
infrastructure. Analysis led the city to
adopt 20 pilot projects, short-term
strategies to supplement existing
stormwater control efforts, medium-
term strategies to develop cost-
effective source controls, and long-
term strategies to secure funding.
SPU identified most economically
feasible options and proceeded with
design phase. By integrating LID/GI
into asset management process, SPU
can minimize life-cycle costs to meet
established levels of service and
balance the risks to minimize life-cycle
costs.
Lower maintenance and repair costs
for deicing permeable pavement result
in projected savings over the life-span
of the pavement. Analysis helped West
Union secure funding. Without it, grey
infrastructure approach would have
been implemented.
Today nearly all CIP projects
(including projects other than just
transportation) contain LID/GI
elements, including many of the
projects evaluated in the feasibility
study. LID/GI options for CIP projects
are investigated as early in the
planning phase as possible.
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The Economics of Low Impact Development and Green Infrastructure Programs
5. Economic Analyses of LID/GI Programs
Entity
LID/GI program
description
Role of analysis
Type of
analysis
Key metrics
Outcome of analysis
Kane County, IL
Milwaukee
Metropolitan
Sewerage District
(MMSD), Wl
Alachua County
Environmental
Protection and
Public Works
Departments, FL
Adoption of county
stormwater ordinance and
corresponding LID/GI-
based BMPs, including
development approaches
that preserve natural areas
and use naturalized
drainage/retention/detention
(i.e., conservation-based
development).
Integration of distributed
LID/GI strategies into
overall planning efforts
including facilities plans
and CSO control plan;
projects on both public and
private lands.
County acquires and
preserves open-space lands
through ACF program to
reduce development impacts
and improve water quality.
Gain support from Fiscal impact
communities within Kane analysis
County for
BMPs/conservation-
based development
• Identify most cost-
effective solution for
integration of Gl into
pilot sewer shed
management program
• Demonstrate
environmental and
social benefits of Gl
Demonstrate benefits of
ACF to alleviate public
concerns that the
program reduces
property tax revenue
• Cost ef-
fectiveness
• Benefit
valuation
Benefit-cost
analysis (BCA)
County revenues and
expenditures over time
under conservation-based
and conventional
development alternatives
• PV cost per stormwater
volume reduction
• Stormwater performance
measures
• Avoided grey
infrastructure costs
• Quantified (and some
monetized)
environmental and social
benefits
• Increase in property
values from increased
open space
• Lost tax revenue from
acquiring private
property for the ACF
program
Study found that conservation
development alternative incurs a lower
public cost than the conventional
alternative. Conservation-based BMPs
were integrated into county stormwater
ordinance/land development
standards. In general, municipalities
were supportive and responsive to the
proposed land use changes.
Results will be used to help select
which projects to implement in the
future, and to show where the use of
Gl is a valid and effective approach.
MMSD believes that the analysis will
help MMSD employees, regulators,
and the public understand the multiple
benefits of Gl and move it forward.
Proximity to open space adds to parcel
value, for an increase in property tax
revenue of several million dollars per
year compared to not having the
added open space parcels.
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The Economics of Low Impact Development and Green Infrastructure Programs
5. Economic Analyses of LID/GI Programs
Entity
LID/GI program
description
Role of analysis
Type of
analysis
Key metrics
Outcome of analysis
Portland Bureau of
Environmental
Services (BBS), OR
Sun Valley
Watershed,
LACDPW, CA
PWD, PA
Ecoroof Program includes
incentives for green roofs on
privately owned buildings
and green roof requirements
for new city-owned buildings.
Goal of watershed-based
project was to alleviate
localized flooding while
providing multiple benefits.
Fifteen project elements with
LID/GI components.
Green City Clean Waters
Program aims to reduce
CSOs and improve water
quality in part through
distributed Gl controls and
comprehensive stream
restoration program.
Gain program support
Increase
implementation of
ecoroofs in the city
BCA analysis
Demonstrate higher
benefit-cost ratio of Gl
compared with grey
infrastructure (despite
higher costs)
BCA analysis
Demonstrate full range
of societal benefits of Gl
to regulators and public
BCA analysis
1. PV life-cycle costs
2. Avoided costs
3. Environmental and
social benefits
4. Net PV benefits
• PV costs for capital,
land, and O&M
• Environmental and
social benefits
• Benefit-cost ratio
• Net PV life-cycle costs
and benefits of Gl and
grey approaches
• Quantified and
monetized social and
environmental benefits
Ecoroofs generate significant public
and environmental benefits, as well as
benefits to developers and building
owners (due to extended life of
ecoroofs compared to traditional
roofs). Documenting benefits has
encouraged development of ecoroofs
and justified the use of financial
incentives to encourage private sector
implementation.
Demonstrated potential for multi-
objective stormwater strategies to
provide greater community value than
a single-objective flood control strategy
would provide. By quantifying benefits,
LACDPW has engaged a wide range
of agencies and stakeholders that
might not otherwise have participated
or provided funding for the program.
LID/GI-based approaches provide
important environmental and social
benefits that are generally not provided
by grey infrastructure. Analysis helped
PWD to determine that a Gl-based
approach, coupled with targeted grey
infrastructure, is their preferred
approach for city to follow.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
6. Key Findings from the Case Study
Economic Analyses
This section highlights the key findings from EPA's assessment of the economic analyses
conducted by the case study entities.
6.1 Factors Influencing the Selection of Economic Analysis
Methods
Utilities and other implementing agencies are using a variety of economic analysis techniques to
evaluate stormwater management alternatives. As evidenced in the case studies, economic
analyses can range in complexity from a simple assessment of the capital costs of various
alternatives to a comprehensive evaluation of the non-market benefits and costs of LID/GI
practices. The choice of a specific technique or type of analysis depends on a variety of factors,
including the objective(s) of the economic analysis which may include gaining stakeholder
support, alleviating public concerns, identification of economically feasible solutions, etc.
Budgetary issues also may influence the analytic methods selected. A full BCA will provide
decision makers the best information for use in policy development. However, budget, time, and
availability of data can make a full BCA difficult to complete. In those situations a less rigorous
analysis can be of use, such as qualitative ranking or cost-effectiveness.
Regardless of the type of analysis chosen, it is important to identify and qualitatively describe the
benefits associated with different LID/GI approaches. (See Section 1.3, How to Use This Report,
for additional ideas on how to select an appropriate analyses.)
6.2 Using Economic Analyses to Address Public Concerns and
Gain Stakeholder Support
In the case studies that show that the adoption of LID/GI practices have a net positive value to
society, this provides an important basis for addressing concerns expressed by the public and the
development community and for gaining stakeholder support. Depending on the scope and
application of the policies being considered, and the value assigned to benefits, not all analyses
may show a net positive value. More specifically, economic analyses that found a net positive
value from LID/GI were used to obtain:
> Community and public support. In response to public concern regarding the potential loss
of property tax revenues associated with preservation of open-space lands, Alachua
County, which includes Gainesville, Florida, conducted an economic analysis to quantify
the change in property values that would result from the additional green space. The county
analyzed real estate sales to show that the increase in land values for properties adjacent to
open space more than offsets the property tax revenue loss associated with acquiring open
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
space for preservation. Kane County, IL conducted a fiscal impact study to gain support
from the communities in the county for the integration of LID/GI-based BMPs into
stormwater and land development standards. In partnership with the Conservation
Foundation, Kane County presented its fiscal impact analysis to all 26 communities in
Kane County. The analysis provided evidence that municipalities can save money by
adopting conservation-based approaches for stormwater management. In general,
municipalities supported the proposed land use changes. The Milwaukee Metropolitan
Sewerage District (MMSD) also conducted a BCA analysis of the economic,
environmental, and social benefits associated with one of its proposed LID/GI program
options to garner public support for its GI approach. This analysis is an important
component of MMSD's public education campaign.
Support and funding from a wide range of stakeholders. By serving the interests of multiple
stakeholders instead of a single-purpose flood control project, the Los Angeles County
Department of Public Works (LACDPW) was able to gain the support of a wide range of
agencies and stakeholders that might not otherwise have been interested in participating in
or providing funding for its Sun Valley Water shed Management Plan. Supporting
organizations included local, state, and federal agencies and nonprofit groups whose
missions or activities are tied to the benefits achieved through the plan such as flood
control, water quality protection and improvement, ground water recharge , ecosystem
restoration, and recreation. LACDPW s BCA demonstrates the potential for multiple-
objective stormwater strategies to provide greater value to the community than a single-
objective flood control strategy.
Developer support. Before adopting LID/GI-oriented development standards and a systems
development fee for new development, the City of Lenexa (Kansas) analyzed potential
impacts for different types of developments including residential, multi-family and
commercial development. As noted above, the analysis showed substantial cost savings
associated with implementing LID/GI-oriented BMPs compared to traditional development
approaches. As a result of the analysis, the Lenexa City Council adopted the development
standards and an accompanying BMP manual. In addition, the city gained developer
support for adoption of the ordinance and the systems development fee. The Portland
Bureau of Environmental Services (BES) conducted an economic analysis of the long-term
costs and benefits of green roofs which convinced the Portland City Council to adopt a
Green Building Policy that requires construction of an ecoroof for all new city-owned
facilities and roof replacement projects if technically feasible. The policy includes an
incentive that offers developers floor area bonuses, which allows additional building space
to be constructed if the building is designed with green roofs. The main purpose of the
Portland BES benefit-cost analysis of ecoroofs described in the case study was to provide
further support for these programs and to encourage future construction of ecoroofs in the
city. Alachua County used the results of its economic analysis of property values, described
above, to alleviate potential concerns from the development community.
Cost-sharing support from Watershed Districts and other partners. The Capitol Region
Watershed District (CRWD) conducted cost-effectiveness evaluations to gain support from
multiple jurisdictions for the implementation of an LID/GI approach to water resource
management. The Los Angeles County Department of Public Works (LACDPW)
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
recognized the importance of involving the community to ensure success. By quantifying
and monetizing the benefits associated with its proposed projects, the LACDPW was able
to obtain support, including financial assistance, from a wide range of stakeholders and
local agencies that might not otherwise have been interested in supporting the projects.
> Local, state, and federal government policy and financial support. West Union reports that
the results of its economic analysis played an important role in gaining public and city
council support for its Green Streets Pilot Project. The analysis also helped the city obtain
financial support for the project because granting agencies were able to evaluate the
positive economic aspects of the program as part of the grant application and review
process. Results from the Philadelphia Water Department's (PWD) BCA (referred to by
PWD as TBL analysis to emphasize the social, environmental, and financial aspects) were
used not only to gain support from local stakeholders but also to encourage EPA to allow
GI alternatives in combination with conventional CSO mitigation infrastructure.
6.3 Using Economic Studies to Optimize the Benefits of
Infrastructure Investments
Utilities can use the results of economic analyses to prioritize and implement the most feasible or
effective LID/GI approaches, and obtain a more clear understanding of the benefits of project or
policy alternatives. For example:
> The Capitol Region Watershed District determined that LID/GI approaches could achieve
stormwater runoff goals for its watershed managment project at a lower cost than the
proposed construction of a 60-inch storm sewer pipe. CRWD then developed an approach
for assessing the cost and effectiveness of LID/GI options. The findings were used to assess
the relative costs and cost-effectiveness of the options in easily understood units such as
dollars per pound of pollutant removed. This approach now serves as a water resource
model for determining how to best achieve volume reduction and water quality in dense
urban watersheds.
> Charlotte-Mecklenburg Storm Water Services initiated LID/GI approaches because model
results indicated LID/GI was the only approach that could achieve sufficient pollutant
removal and prevent further degradation of the county's waterways. The county's analysis
showed that stream restoration was the most cost-effective way to immediately reduce
sediment loadings through the stabilization of eroding streambeds damaged from excess
urban runoff.
> New York City's Sustainable Stormwater Management Plan provides a comprehensive
analysis of the feasibility and cost-effectiveness of stormwater management alternatives.
The city found that its proposed LID/GI strategies—which include sidewalk standards,
road reconstruction standards, green roadway infrastructure, and stormwater requirements
and incentives for low- and medium-density residences and other existing buildings—
present significant opportunities for cost-effectively controlling stormwater and reducing
CSOs compared to the conventional pipe, tunnel and treatment alternatives for CSO
control. Based on the analysis conducted as part of its Sustainable Stormwater
Management Plan, the city developed and prioritized a series of promising stormwater
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
strategies and pilot projects. The pilot projects provide a framework for further testing,
assessment, and implementation of decentralized source controls. Other analyses conducted
by NYC point to some combination of significant cost savings, and higher net benefits
compared to grey infrastructure approaches.
6.4 LID/GI Can Cost Less than Grey Infrastructure Alone
In addition to assessing the economic feasibility of LID/GI approaches, the case study entities
used both simple and more complex economic analyses to compare LID/GI-based approaches
with more traditional, solely grey infrastructure technologies. Many entities found cost savings
associated with LID/GI-based alternatives. For example:
> The City of Lenexa, Kansas, found substantial cost savings associated with implementing
LID/GI-oriented BMPs for multi-family, commercial, and warehouse developments in
contrast to traditional stormwater management approaches using grey infrastructure.
> West Union, Iowa, compared the life-cycle costs (the total capital and O&M costs for the
project) of a permeable paver system in the downtown area with those of traditional
bituminous or Portland cement concrete pavement. Results showed that although
permeable pavement will initially be more expensive, the lower maintenance and repair
costs will result in cost savings in the long run. The city would begin to realize these cost
savings by year 15 of the project. Estimated cumulative savings over a 57 year period were
calculated to amount to about $2.5 million
> The Capitol Region Watershed District in Minnesota found significant capital cost savings
for LID/GI approaches compared to grey infrastructure. A new storm sewer for conveying
untreated, frequent floodwaters to Lake Como was estimated to cost $2.5 million compared
to $2.0 million for implementing GI infiltration practices. In addition, the district found that
LID/GI approaches would result in a significant benefit—by improving the quality of an
economically important, nutrient-impaired recreational lake.
> In Portland, the Bureau of Environmental Services (BES) calculated the NPV of its ecoroof
program to the public, i.e., the public stormwater system and the environment and to
private property owners such as developers and building owners. BES concluded that
ecoroof construction provides both an immediate and a long-term benefit to the public. The
net present benefit is $101,660 at year 5 and $191,421 at year 40. For building owners, the
benefits of ecoroofs do not exceed the costs until year 20, which is the point at which
conventional roofs require replacement. In the long term for the 40-year life of an ecoroof,
the net present benefit of ecoroofs to private stakeholders is more than $400,000.
6.5 LID/GI Approaches Result in Multiple Benefits
The multiple environmental, social, and financial benefits of LID/GI must be considered when
determining the most appropriate approaches to implement. Almost all case study entities
recognized the importance of the multiple benefits associated with LID/GI and developed both
quantitative and qualitative ways to value these benefits when they made their stormwater
management decisions.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
In Milwaukee, Portland, Philadelphia, and the Sun Valley watershed of Los Angeles County,
case study entities quantified and monetized benefits using non-market, or avoided cost,
economic valuation techniques. Some entities identified the key benefits of LID/GI in their
analysis but did not assign a value to those benefits. Several entities recognized the importance
of the multiple benefits of LID/GI and indicated that they hope to be able to quantify the benefits
in the future. Entities that incorporated these economic valuation techniques into their analyses
include the following:
> The Portland Bureau of Environmental Services identified and/or quantified and monetized
a wide range of benefits from ecoroof construction. Key benefits monetized in the city's
benefit-cost analysis included (1) public benefits of reduced stormwater system
management costs, habitat creation, improved air quality, and reduced carbon emissions
and (2) private benefits to developers and building owners from stormwater volume
reduction, reduced energy demand for heating and cooling, avoided stormwater facility
costs, increased roof longevity, and reduced cost due to heating, ventilating, and air-
conditioning equipment sizing. Portland found that, over time, the public and private
benefits of ecoroofs exceed the costs.
> The Philadelphia Water Department performed a full BC A comparison of green versus
grey infrastructure to evaluate the best approach for investing the city's funds to solve the
CSO problem in a dense urban environment. The analysis demonstrated that for equal
investment amounts and similar overflow volume reductions, the use of LID/GI would
provide 20 times the benefits of traditional stormwater infrastructure such as large tunnels
and pumping stations. The benefits quantified and monetized as part of this analysis
included increased recreational opportunities, air quality improvements, water quality and
ecosystem enhancement, creation of LID/GI-based jobs, increased property values, and
reduced urban heat stress.
> The Los Angeles County Department of Public Works (LACDPW) monetized the multiple
benefits associated with its proposed LID/GI-based alternatives, including benefits
associated with water conservation, recreational opportunities, improved community
aesthetics, increased wildlife habitat, and reduced stormwater pollution. By looking at the
benefits per unit cost, rather than just lowest capital cost, LACDPW was able to provide a
solution with more long-term value to the community and, also serve as a model for the
region.
> The Capitol Region Watershed District (CRWD) and West Union did not quantify the non-
market benefits associated with their LID/GI approaches but did recognize the important
role such approaches played. CRWD recognized that the only benefit of the $2.5 million
grey infrastructure alternative for stormwater management would have been to reduce
localized flooding in Como Park. The $2.0 million LID/GI BMP option not only reduced
flooding but also (1) reduced the volume of stormwater runoff which enhanced ground
water supplies; (2) improved water quality in an impaired lake; and (3) enhanced the
recreational amenities in Como Park. In West Union's life-cycle cost analysis of permeable
versus traditional pavement systems, the city recognized, but did not quantify, the benefits
of permeable pavement, such as improved water quality, increased stream health and
appearance, reduced storm sewer infrastructure and maintenance, improved pavement
surface temperatures, and improved street appearance.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
6. Key Findings from the Case Study Economic Analyses
6.6 LID/GI Approaches Can Be Successfully Integrated into
Capital Improvement Programs
Economic analyses of LID/GI programs have been used to establish processes for capital
improvement planning and other planning efforts. For example:
> The project evaluation matrix used in Kirkland's (WA State) feasibility study helped to
provide the institutional framework needed to successfully incorporate LID/GI elements
into the city's transportation CIP projects. Kirkland Public Works Department staff view
the study as an important initial resource, and today most CIP projects (including non-
transportation projects) contain LID/GI elements, including many of the projects evaluated
in the feasibility study. Today, LID/GI options for CIP projects are investigated as early in
the planning phase as possible.
> Subsequent to development of Fresh Coast Green Solutions, the Milwaukee Metropolitan
Sewerage District (MMSD) initiated a more detailed analysis of the potential of GI
strategies to help eliminate overflows and provide additional benefits. They produced a
study called, Determining the Potential of Green Infrastructure to Reduce Overflows in
Milwaukee, that is intended to be used to optimize the implementation of GI throughout
MMSD's service area. As a result of these planning efforts, LID/GI has been integrated
into MMSD's 2020 facilities planning effort, which is based on a watershed approach.
Subsequent analyses and related reports will enhance integration of GI into the 2035 or
2040 facilities plans. (Planning will begin in 2013.) As part of its "adaptive management"
approach to stormwater management, MMSD plans to continue evaluating the
effectiveness and benefits of LID/GI practices as implementation becomes more
widespread and more lessons are learned.
> A key outcome of Charlotte-Mecklenburg Storm Water Service's analysis is that
Mecklenburg County (NC) has begun to shift from implementing opportunity-based
projects to implementing need-based projects. This strategy includes the examination of a
number of drivers that influence the selection and implementation of projects that will
provide the largest benefits.
> The Los Angeles County Department of Public Works established the long-term benefits of
LID/GI in the Sun Valley Water shed Management Plan. With the success of this approach,
the Department now includes LID/GI analysis in future capital projects.
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Case Studies Analyzing the Economic Benefits of Low Impact Development and Green Infrastructure Programs
7. Lessons Learned
7. Lessons Learned
Case study entities used economic analysis to gain valuable insights, deal with unexpected
challenges, and learn many valuable lessons. The challenge most frequently mentioned entailed
difficulties in developing estimates of the costs and benefits of their LID/GI projects. A number
of entities also noted lessons learned related to maintaining their LID/GI systems, as these are
not familiar systems to most municipal stormwater maintenance crews. Many case study entities
stressed the importance of stakeholder involvement throughout the development and
implementation of LID/GI programs. In addition, many entities indicated they would like to
improve or expand their analyses, perhaps by adding more program areas or monetizing more
factors, but did not have the resources to do so.
As noted in the Introduction, the objectives of this document are to highlight different analysis
methods that have been successfully applied and to demonstrate cases where LID/GI has been
shown to be economically beneficial. The following sections highlight key lessons learned, as
communicated by the case study participants.
7.1 Track and Analyze LID/GI Capital and O&M Costs to Plan
and Budget Effective Programs
> Track the costs of O&M activities over time. Many case study entities indicated that they
would like to obtain better estimates of the O&M costs associated with different types of
LID/GI projects. The Seattle Public Utilities in Washington tracks information on the
actual O&M costs of its NDS projects and uses this information to revise and improve
estimates for new projects.
> Review O&M and capital cost data from other entities, but be aware that these data might
not apply to all situations. For West Union, IA, for example, a key challenge in putting
together its economic analysis was being able to compare up-front and long-term costs for
LID/GI-based practices. The city found that urban-based estimates of costs and benefits did
not transfer very well to its smaller, rural community. For example, West Union compared
the capital and O&M costs of the permeable paver system with those associated with
constructing and maintaining traditional types of pavement. Because West Union is a small
community with limited resources, it lacks regular maintenance plans for its infrastructure.
Thus, the city will not realize the same cost savings as larger cities that can better maintain
their roads.
> Develop accurate estimates of land acquisition costs. Los Angles CDPW reports that costs
associated with private land acquisition for LID/GI can be higher than originally
anticipated. Given the county's financial situation, cost increases for some projects might
affect the ability to implement future projects although LACDPW hopes to design future
projects to capture more stormwater in order to reduce the need for projects in other
locations.
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7. Lessons Learned
7.2 Build LID/GI O&M Activities into the Program Framework
The use of LID/GI practices for stormwater management is a relatively new concept in many
communities. When implementing these new technologies, many entities experienced
unexpected maintenance concerns, as described below. Maintenance issues are expected to
decrease as LID/GI implementation becomes more widespread.
> Designate O&M responsibilities clearly. Often, developers are not held responsible for
O&M after they install recommended BMPs. In many instances the community is not able
keep up with the maintenance, especially if it has no group or department to take charge.
To deal with this problem, Kane County, IL initiated a special service area tax to fund the
maintenance of stormwater management BMPs. When implementing a GI project on
private lands, MMSD establishes a formal agreement with the property owner that lays out
a cost-share and post-construction maintenance plan. MMSD has no liability for these
projects. For CIP projects in residential areas, Kirkland, WA established partnerships with
homeowners' associations to perform maintenance.
> Expand staff skill set for different maintenance needs. The skill set required for maintaining
traditional CIP projects differs considerably from the skill set needed to maintain LID/GI
components. As a result, maintenance staff might show some resistance, which has been a
problem for some case study entities. The Kirkland Public Works Department sometimes
obtains maintenance support from the Parks and Recreation Department. However,
Kirkland considers supplemental training for CIP maintenance staff the long-term solution.
> Educate public participants involved in LID/GI practices. MMSD in Milwaukee, WI
learned that in addition to requiring a formal agreement, projects on private lands are most
successful when project owners understand and support GI and receive training on how to
maintain the projects. It is also important to educate the public on how to keep conservation
areas in their neighborhoods healthy by not mowing open-space areas intended to serve as
prairie habitat and not tossing yard waste into wetland areas.
> Seek associations and partnerships to reduce training costs. Kirkland has supplemented its
own training with training provided by a local nonprofit organization. It has also developed
partnerships with homeowners' associations to maintain GI projects.
7.3 Encourage Stakeholder Involvement and Education
A key lesson learned by the case study entities is the importance of stakeholder involvement
when developing and implementing LID/GI programs. Key stakeholders include decision
makers, potential funders, partnering agencies, program staff, special interest groups, and the
public. Examples of challenges and lessons learned related to stakeholder involvement are
provided below.
> Include stakeholders at all levels of decision making. Lenexa' s Rain to Recreation program
is well supported by the city's residents and serves as a model for cities throughout the
country. The city believes that this is largely because it has been open and transparent in
developing its program and has included stakeholders throughout the process. For example,
the city's BMP manual was developed through a cooperative effort led by the Kansas City
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7. Lessons Learned
Metro Chapter of the American Public Works Association, in coordination with the Mid-
American Regional Council and a host of municipalities in the Kansas City region. The city
continues to work with development interests and hosted a BMP workshop for construction
industry professionals. In addition, the system development fee adopted by the city council
was the result of a multi-stakeholder process that included the Lenexa Economic
Development Council and the Homebuilders Association.
LACDPW also stresses the importance of involving the community and other stakeholders
at all levels of project design and implementation. LACDPW worked with an
environmental nonprofit organization, TreePeople, to educate stakeholders at community
events. The district also developed a project website that is actively used and frequently
updated. Bringing stakeholders in early has been critical to LACDPW's success.
Gain support from agencies and staff involved in implementing LID/GI approaches. New
York City recognizes that a key challenge for its program will be to successfully coordinate
the various agencies and stakeholders involved in implementing the stormwater
management plan. Many agencies are supportive of LID/GI but are concerned about the
operation and maintenance (O&M) costs associated with this type of infrastructure.
When MMSD (Milwaukee, WI) began implementing GI in 2002, there was little support
within the water and wastewater community or within the utility. In addition, although
regulators such as EPA, the mayor, and the State of Wisconsin had been supportive, they
were not fully on board with the GI approach. Gaining internal support was an initial
critical concern. Support has increased over time because of successful demonstration
projects, education, and the hiring of staff familiar with the GI approach. Overall, MMSD
recognizes that although reducing overflows and improving water quality are its main
concerns, TBL benefits are important.
Communicate the results of economic analyses. Kane County, IL, believes that one reason
its communities have been supportive of its watershed planning efforts is that the county's
proposed programs and economic analysis were clearly communicated by a well-respected
community member. The county also learned that it is necessary to clearly communicate
with developers about new conservation requirements. Up-front communication
encouraged developers to comply with these changes.
Use demonstration projects as a public education tool. MMSD (Milwaukee, WI) achieved
valuable public outreach benefits from its GI demonstration projects. For example,
implementation of a rain garden demonstration project in a public building influenced local
residents to install rain gardens in their own yards. Neighborhood associations and schools
have also effectively brought ideas to the public.
Be open and transparent about assumptions. The Philadelphia Water Department
recognizes that analyses of social and environmental benefits invariably require the use of
assumptions and approaches that interject uncertainty about the accuracy or
comprehensiveness of the empirical results. Throughout its analysis, PWD was explicit and
reasonable about its assumptions and approaches. For transparency purposes, the research
team identified key omissions, biases, and uncertainties embedded in the analysis and
described how the results of the analysis would likely have been affected, i.e., benefits
would have increased, decreased, or changed in an uncertain direction if the omission or
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7. Lessons Learned
data limitation had been avoidable. In conjunction with these issues, a series of sensitivity
analyses were conducted to explore how changing some of the key assumptions would
affect findings.
7.4 Plan and Budget Additional Analysis to Evaluate LID/GI
Programs and Projects
Many case study entities indicated that they would like to conduct additional analysis, including
quantifying or monetizing the benefits associated with their LID/GI projects and programs. In
many cases, analysis has been limited by insufficient data or by a lack of available resources,
expertise, or both. These needs for additional analysis are described below.
> Identify ways to finance economic analyses. Lack of available resources was cited as a
primary reason for not conducting more in-depth analysis. For example, Kane County, IL
considered conducting a fiscal impact analysis that would assess costs to developers, with
the expectation that the costs associated with conservation-based systems would be lower
than those associated with conventional systems and would also result in higher property
values and higher profits. However, the county did not have sufficient resources to conduct
such a study.
> Investigate ways to quantify and/or monetize the benefits of LID/GI approaches. Many case
study entities indicated that they would like to be able to quantify and/or monetize the non-
market or external benefits associated with LID/GI approaches but they lack the necessary
expertise, data, or both to do so. For example, Portland BBS quantified many of the
benefits of ecoroofs and found that publicizing these benefits presents a convincing
argument for the program. However, BES faced constraints in quantifying additional
benefits, including difficulties in extrapolating findings from the literature to the City of
Portland and monetizing benefits. Seattle Public Utilities conducts economic analysis of its
proposed programs using cost-effectiveness analysis and some TBL components. However,
the utility has not been able to quantify and/or monetize many of the environmental and
social benefits of its projects because of a lack of available resources and expertise.
The case studies in this report provide a compelling case for the benefits of evaluating
LID/GI, in combination with grey infrastructure, as an alternative to traditional grey-only
stormwater infrastructure. As LID/GI practices become more established, it will become
easier to identify, quantify, and monetize the benefits, and also to address the issues
associated with O&M.
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Appendix: LID/GI Case Studies
Appendix: LID/GI Case Studies
A. 1 Sun Valley Watershed, California: Evaluating the Benefits of Using Green
Infrastructure to Reduce Localized Flooding A-2
A.2 Alachua County, Florida: Preserving Suburban Lands to Improve Water Quality
Provides a Good Return on Investment for the Community A-ll
A.3 Kane County, Illinois, Blackberry Creek Watershed: Finding that
Environmentally Sensitive Land Development Is Also Fiscally Responsible A-17
A.4 West Union, Iowa: Long-Term Cost Savings Plus Environmental and Social
Benefits Envisioned in Rural Green Streets Pilot Project A-25
A.5 Lenexa, Kansas: Demonstrating Cost Savings Associated with New LID/GI
Development Standards A-30
A.6 Capitol Region Watershed District, Minnesota: Realizing Cost Savings and
Environmental Benefits by Using Green Stormwater Infrastructure Retrofits A-35
A.7 New York City, New York: Bringing Together Agency Stakeholders to Assess
the Cost-Effectiveness and Feasibility of Sustainable Stormwater Management in
Combined Sewer Overflow Areas A-42
A. 8 Charlotte-Mecklenburg Storm Water Services, North Carolina: Using Cost-
Effectiveness Analyses to Prioritize Projects that Reduce the Impacts of Rapid
Development A-49
A.9 Portland, Oregon: A Benefit-Cost Analysis Provides the Basis for Incentivizing
Ecoroof Construction A-55
A. 10 Philadelphia, Pennsylvania: A Triple-Bottom-Line Analysis of Combined Sewer
Overflow Control Options A-61
A. 11 Kirkland, Washington: Ranking Benefits to Help Assess the Feasibility of LID/GI
Approaches in CIP Transportation Projects A-68
A. 12 Seattle, Washington: Using an Asset Management Approach for Optimizing
Green Stormwater Infrastructure Application A-76
A. 13 Milwaukee, Wisconsin: Optimizing the Potential for Green Infrastructure to
Reduce Overflows and Provide Multiple Benefits A-88
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Appendix: LID/GI Case Studies
A.1 Sun Valley Watershed, California: Evaluating the Benefits of
Using Green Infrastructure to Reduce Localized Flooding
Entity
Name: Los Angeles County Department of Public Works (LACDPW). The Sun Valley
Watershed Management Project is directed by LACDPW. Members of the Sun Valley
Watershed Stakeholders Group, other agencies, elected officials, civic groups, businesses,
nonprofit organizations, and individuals are also involved in the decision-making process.
Population served: 80,000 residents within the watershed
Area: The Sun Valley watershed is in the San Fernando Valley, about 14 miles northwest of
downtown Los Angeles. It encompasses the communities of Sun Valley and North Hollywood.
The watershed is approximately 4.4 square miles and six miles in length from north to south.
Project highlights
By adopting a plan to alleviate local flooding problems while providing multiple benefits,
including water conservation, recreational opportunities, improved community aesthetics,
increased wildlife habitat, and reduced stormwater pollution, LACDPW has found:
> Although LID/GI-oriented solutions cost more than more traditional approaches in this
setting, these solutions yield a much higher benefit-to-cost ratio.
> By looking at the benefits per unit cost, rather than just lowest capital cost, LACDPW was
able to provide a solution with more long-term value to the community and, by leading by
example, to the greater region at large.
> Public participation has been integral to the development and implementation of the
watershed-based approach encompassed in the Sun Valley Watershed Management Plan.
I By quantifying and monetizing the benefits associated with proposed projects, LACDPW
has been able to engage support, including financial assistance, from a wide range of
agencies and stakeholders that might not otherwise have been interested in participating in
the project or providing funding.
> In addition to the overall benefit-cost analysis undertaken as part of the plan, project-
specific benefit-cost analyses will be necessary to further refine and, potentially,
re-prioritize projects.
Background
For many years, the Sun Valley watershed has been faced with the need to solve its frequent
flooding problems. This highly urbanized watershed is not served by a comprehensive
underground storm drain system. During rainfall events, stormwater flows are conveyed along
street surfaces, and water collects at several of the major intersections in the area. Even moderate
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rainfall causes flooding on the order of two to three feet in depth, impeding pedestrian and
vehicle traffic.
In addition to flooding problems, much of the runoff from the Sun Valley watershed is lost to the
Los Angeles River as a result of the large amount of urbanization in the watershed. This has
largely reduced infiltration and recharge, resulting in reduced availability of local groundwater
supplies. In a region heavily dependent on imported water supply, the capture and reuse of runoff
is an important benefit of Sun Valley's flood reduction program.
To alleviate the area's flooding problem, LACDPW initially proposed a storm drain project
called Project 9250. The project involved constructing a system of storm drains throughout the
watershed so that the majority of the stormwater flows would be conveyed below the streets.
Project 9250 was last proposed in 1989, but it was never implemented, primarily because of a
lack of funding and community support.
Although the storm drains would efficiently convey stormwater away from people and
properties, this solution would not help to improve water quality in the Los Angeles River, which
is listed as a 303(d) impaired water body largely because of urban runoff. The project would also
not improve groundwater infiltration and recharge rates.
LACDPW, in coordination with a number of other agencies and stakeholder groups, has
therefore proposed a series of LID/GI-oriented solutions as part of the Sun Valley Watershed
Management Plan. The plan offers a multipurpose approach to stormwater management that is
responsive to the need to integrate flood control, stormwater pollution reduction and water
supply efforts. The plan also addresses additional community issues, such as the lack of
recreational resources, wildlife habitat, and aesthetic amenities in the watershed.
Types of LID/GI solutions
The plan evaluates the feasibility of four stormwater management alternatives that consist of
various combinations of specific LID/GI components focused on infiltration, water conservation,
stormwater reuse, and subsurface conveyance systems and site specific BMPS such as mulching
and tree planting. Example pilot project components include infiltration basins, e.g., Sun Valley
Park Project, constructed wetlands, tree planting, development of parks and open space, and
storm drains designed to convey stormwater to the project areas.
In addition, as part of the plan effort, Tree People, a nonprofit organization working in
coordination with LACDPW, is working with Sun Valley residents to implement a green street
project in the watershed. The project includes the construction of vegetated swales, structural
elements to direct runoff from driveways into the swales, and cisterns.
Program description
Public participation has been integral to the development of the Sun Valley Watershed
Management Plan. In 1998 LACDPW invited area residents, state and local agencies, local
businesses, and environmental groups to form the Sun Valley Watershed Stakeholders Group.
The purpose of this group is to develop a holistic solution to the area's flooding problem that
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would be an alternative to traditional storm drains and would provide multiple benefits for the
community. The mission of the group is:
"... to solve the local flooding problem while retaining all stormwater runoff from the
watershed, increasing water conservation, recreational opportunities, and wildlife habitat,
and reducing stormwater pollution."
LACDPW developed the objectives of the plan based on the mission statement of the group.
Specific goals include:
> Reduce local flooding.
I Increase water conservation. The general goal for water conservation is to retain all
stormwater runoff within the watershed for rainfall events up to the 50-year storm.
Potential uses of captured stormwater include groundwater recharge to augment the local
water supply and substitution for existing uses that do not require potable water,
e.g., industrial washwaters or irrigation.
> Increase recreational opportunities. The plan contains a proposal for a series of flood
control facilities designed to serve as parks, open space, or both. These areas will provide
increased recreational opportunities for the residents of the Sun Valley watershed.
> Increase wildlife habitat. The plan incorporates flood control facilities designed to also
serve as wildlife habitat areas. For this objective LACDPW follows the qualitative goals
outlined in the City of Los Angeles General Plan (2001), which includes the following
objective: "Protect and promote the restoration, to the greatest extent practical, of sensitive
plant and animal species and their habitats." Examples of additional goals for habitat
development include (1) increasing the number of species, (2) increasing the ratio of native
to nonnative species, (3) increasing the diversity of native habitat types, and (4) connecting
existing adjacent significant habitat areas.
> Improve water quality. Specific plan goals for improving water quality include reducing
the pollutant load entering the Los Angeles River by retaining stormwater runoff within the
watershed up to the 50-year frequency storm, improving the quality of urban runoff
through use of stormwater quality BMPs, proactively enforcing regulations on illegal
discharge, educating the public on responsible management practices, and maintaining or
improving existing groundwater quality.
> Provide additional environmental benefits. The plan focuses on the development of
strategies that will achieve multiple environmental benefits. For example, tree planting can
help reduce urban runoff while providing shade for buildings, resulting in lower energy
needs for air-conditioning. Project components incorporated into the plan aim to maximize
these types of environmental benefits.
> Increase multiple agency participation. The plan aims to encourage a more involved
government and community, attract multiple funding partners, work with local schools to
provide aesthetic and other benefits for their campuses, and increase public awareness of
watershed issues.
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Using these goals and objectives, LACDPW developed a broad range of possible options. The
range of possibilities was then narrowed down to four final alternatives, each of which was
focused on a specific stormwater strategy: infiltration, water conservation, stormwater reuse, and
urban storm protection that would be achieved (through the use of subsurface conveyance
systems and regional BMPs). Each alternative is a collection of project components, and many of
the components are used in more than one alternative. Examples of project components include
infiltration basins, constructed wetlands, tree planting, street storage, parking lot infiltration, and
tunnels or storm drains.
Exhibit A. 1.1 provides a summary of the four sample alternatives.
Exhibit A. 1.1. Final four sample alternatives of the Sun Valley Watershed
Management Plan
Description
Retention basin size
Alternative 1 :
Maximize
infiltration
Widely distributed
small projects
50 years
Alternative 2:
Maximize water
conservation
Maximizes wildlife
habitat and water
conservation
50 years in most
watershed subareas
Alternative 3:
Stormwater reuse
Maximizes
stormwater reuse
for industry
50 years
Alternative 4:
Urban storm
protection
Maximizes subsurface
conveyance and
regional BMPs
10 years
Net volume discharged
to Los Angeles River
in 50-year storm
21 acre-feet (AF)
OAF
8AF
598 AF
Alternative 2 had the highest benefit-to-cost ratio and has 15 proposed projects. Two of these
projects have been completed—a groundwater recharge project at Sun Valley Park and an
LZD/GI-oriented flood reduction project aimed to alleviate flooding in a key intersection. The
Sun Valley Park project uses GI to direct runoff into a treatment and infiltration system located
underneath the park property. This project was used as a demonstration project to highlight
partnerships between various agencies and organizations.
Currently, LACDPW is working on a third project called Strathern Pit. The project encompasses
46 acres and will direct water into a landfill for reclamation and a constructed wetland for
treatment. The captured stormwater will then be pumped to Sun Valley Park for infiltration. The
project will include the conversion of an active industrial area into a neighborhood park, and it
will incorporate trails, recreational facilities, potentially include soccer fields and other park
amenities. LACDPW plans to continue with the remaining 12 projects outlined in the watershed
management plan.
In addition to the projects being implemented by LACDPW, the Los Angeles Department of
Water and Power is taking the lead on implementing two projects. The projects include the
implementation of treatment and infiltration BMPs on a 155-acre steam plant site and on a
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smaller power line easement area. These two projects are not part of the Sun Valley Management
Plan, but they stemmed from that effort.
Role of economic analysis
The objective of LACDPW's analysis was to evaluate the costs and benefits, including non-
market benefits, e.g., air quality, water quality, of the four sample alternatives described above.
This analysis allowed LACDPW and project partners to compare multi-objective solutions to the
implementation of a more traditional approach to stormwater management, i.e., Project 9250.
The economic analysis was undertaken because the county and other stakeholders needed to
show that although the costs of the LID/GI-oriented solutions would be much greater than the
cost of traditional infrastructure, and they would yield significantly higher benefits. The results
of the analysis were used to help to gain public support, bring in outside partners, and raise
funds.
Economic analysis method and results
Method: Categories of benefits were developed based on project objectives and an understanding
of future potential funding partners. Various methods were used to quantify these benefits,
including using avoided costs, willingness to pay values from the literature, and valuation
pricing, e.g., increases in property values. Project benefits and costs were evaluated over a
50-year time horizon, assuming a nominal discount rate of 4 percent. The benefits evaluated as
part of LACDPW's analysis include:
> Flood control. Benefits include avoided cost of facilities needed to provide comparable
local and downstream flood protection.
> Water quality improvements. Benefits include avoided costs associated with the removal of
bacteria and other listed pollutants from waters that contribute to impairments of the Los
Angeles River.
> Water conservation. Benefits include cost savings associated with the use of stormwater for
ground water recharge and water supply augmentation compared to costs of purchasing
imported water.
> Energy. Benefits include cost savings associated with reduced energy consumption due to
the planting of shade trees and the decreased amount of energy used to pump imported
water into the Los Angeles Basin due to alternative sources of water, i.e., harvested or
infiltrated runoff.
> Air quality improvements. Benefits include absorption of pollutants by the tree canopy,
pollution reduction achieved through reductions in vehicle emissions due to decreased
greenwaste/yard trimming hauling, and reduced emissions from power plants from
decreased energy consumption.
> Greenwaste/yard trimming reduction. The mulching component of the proj ect would use
all greenwaste that is generated at participating sites and thus reduce the waste stream to
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landfills. Irrigation demand also would be reduced. Benefits include the avoided costs of
hauling and tipping for landfill disposal of greenwaste.
> Ecosystem restoration. Benefits include increased habitat and open space.
> Recreation. Benefits include the value of increased parkland and recreation for the area.
> Property values. Benefits include increased property values due to proximity to the project
site.
The costs of each alternative also were monetized. These costs included capital facilities costs,
land acquisition costs, and expected O&M costs. Capital cost assumptions were developed based
on costs obtained from industry manufacturers, contractor experience on similar planning
projects, and data provided by LACDPW. Annual O&M costs were assumed to remain constant
from year to year.
Results: The results of the benefit-cost analysis are summarized in Exhibit A. 1.2, which shows
the benefit-to-cost ratio for each alternative, including Project 9250. The ratios use the present
value of total project costs and benefits over the 50-year evaluation period. A ratio greater than 1
indicates an alternative with benefits greater than cost; a ratio less than 1 indicates an alternative
with costs greater than benefits.
Exhibit A.1.2. Benefit-to-cost ratio for each Sun Valley stormwater management
alternative
Alternative
Present value (PV) of total
benefits (millions 2002 USD)
PV of total costs
(millions 2002 USD)
Benefit-to-cost ratio
9250
$73.44
$74.46
0.99
Alternative 1 :
Infiltration
$270.47
$230.40
1.17
Alternative 2:
Water
conservation
$295.39
$171.58
1.72
Alternative 3:
Stormwater
reuse
$274.93
$297.90
0.92
Alternative 4:
Urban storm
protection
$239.95
$206.61
1.16
As shown in Exhibit A. 1.2, Alternative 2, water conservation, has the highest benefit-to-cost
ratio at 1.72. This ratio is due to the combination of higher overall benefits and lower total
project costs. The higher benefits are due primarily to the reduced costs associated with the
Tujunga Wash to Sheldon Pit project. This alternative provides almost four times the
groundwater recharge than that provided by any other alternative. This project involves the
conveyance of water from an area highly prone to flooding (Tujunga Wash) to an exhausted
gravel pit (Sheldon Pit) for infiltration and recharge.
The relatively low cost of the water conservation alternative results from a reduction in the
number of retention projects to provide flood control for Sun Valley. This alternative also
included fewer on-site BMPs and less street storage compared to the other alternatives.
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Outcomes: The project has resulted in numerous positive outcomes. The benefit-cost analysis
demonstrates the potential for multiple-objective stormwater strategies within the Sun Valley
watershed to provide greater value to the community than a single-objective flood control
strategy. By quantifying the large number of benefits associated with projects incorporated into
the plan, LACDPW has been able to engage the support of a wide range of agencies and
stakeholders that might not otherwise have been interested in participating in, or providing
funding for, the plan. The agencies and stakeholders include local, state, and federal agencies and
nonprofit groups whose missions or activities are tied to the benefit categories identified above,
e.g., flood control, water quality improvements, ecosystem restoration, and recreation. A list of
potential organization and agency partners is included in Section 5 of the plan (see
http://www.sunvallevwatershed.org/ceqa docs/plan.asp). To date, project partners that have
provided financial assistance, services, or both include LACDPW, TreePeople, CALFED Bay
Delta Program, California State Water Resources Control Board, City of Los Angeles Bureau of
Sanitation, and City of Los Angeles Parks and Recreation.
As a result of this project's success, the county reorganized the LACDPW Flood Control
Department which became the LACDPW Watershed Division. This change represents the shift
toward a more holistic watershed approach.
The plan has helped LACDPW and other organizations, such as Tree People, to obtain funding
for program activities. It is easier for these entities to obtain funding if they can point to the fact
that they are undertaking proposed activities in coordination with a broad, adopted plan.
Residents also may benefit from implementation of the plan because increases in flooding
insurance rates might be avoided. As background, there has been increased public awareness
surrounding LACDPW's plan because Sun Valley residents may soon be subject to federal flood
insurance requirements. If this area is determined to be in a National Flood Insurance Program
flood zone, property values could be adversely affected, building restrictions could increase, and
residents will have to pay for the required insurance if they hold a mortgage. Implementation of
the plan might help alleviate this requirement.
The adoption of the plan also has increased public support. Residents of Sun Valley can see that
progress is being made and that their concerns are being heard.
Lessons learned and next steps
In terms of the economic analysis, LACDPW will continue to conduct benefit-cost analyses on a
project-by-project basis. The analysis presented in the plan was completed in 2004, and costs
have since increased. More detailed analyses will be conducted for each planned project in order
to evaluate implementation.
In addition, some projects, e.g., Strethern Pit will cost much more than originally anticipated,
primarily because of unforeseen costs associated with private land acquisition. Given the
county's current financial situation, cost increases for some projects might affect the ability to
implement others. However, there may be opportunities to change the location and design of
future projects to improve system function and perhaps reduce land acquisition costs.
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Maintenance of the system has been an issue. Many of the projects implemented have high
maintenance requirements, including maintenance associated with water quality monitoring,
high-tech treatment systems, and the cleaning of underground treatment systems. For example,
some projects require monthly calibration of monitoring probes, as well as removal of trash and
cleaning after every storm. Maintenance needs are especially difficult for underground facilities;
for example, air quality testing is required. LACDPW is considering design options to reduce
maintenance needs. It should be noted that the plan does not take into account most of the
maintenance costs associated with current projects and the city does not currently have a plan to
evaluate these costs.
Although maintenance costs are more than those associated with surface controls such as LID/GI
practices opportunities for the use of decentralized surficial source controls are limited in the Sun
Valley watershed because of its highly urban nature and limited land availability. As a result,
infiltration vaults and other regional projects will continue to be an important part of LACDPW s
storm water management program.
In addition to challenges associated with acquiring private lands for project implementation,
LACDPW has had some difficulties working on public lands. For example, the county is
working to implement a project at a local middle school, where flooding has been a large
problem. LACDPW has proposed to put in a facility similar to the one constructed underneath
Sun Valley Park. The school, however, is reluctant to let the county work on its property because
it plans to expand in the future and is concerned that the project will limit its ability to place
structures in certain areas. The two entities are working together to reach an agreement on
project design.
Finally, LACDPW and the project stakeholders realize that to make the plan a reality, the
community must be involved. Involvement is needed at many levels—for example, at the group
level for making project design decisions and at the household and individual levels for tree
planting, mulching, and using BMPs.
Progress is already well under way in educating and developing community interest and
participation. TreePeople and LACDPW staff have made presentations at many community
events. The project website is actively used and maintained. Monthly stakeholder meetings offer
an opportunity for community members to provide ideas and feedback on project elements.
Stakeholders who receive information at the meetings disseminate the information in the
community.
Related links
Similar programs and analyses
Ventura, California's LID/GI-based program has many components similar to those included in
Sun Valley's program. For more information, see
http://www.surfrider.org/ventura/reports/Solving%20the%20Urban%20Runoff%20Problem%20-
%20Ventura.pdf.
The City of Los Angeles has documented many of the benefits of GI implementation within the
city. For more information, see the report Green Infrastructure for Los Angeles: Addressing
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Appendix: LID/GI Case Studies
Urban Runoff and Water Supply through Low Impact Development. This report also contains a
case study of Ventura's LID policies and programs. Available:
http://www.waterboards.ca.gov/water issues//programs/climate/docs/resources/la green infrastr
ucture.pdf
Key sources
For more information on the Sun Valley Watershed Management Plan:
www.sunvalleywatershed.org.
To view the City of Los Angeles General Plan (2001): http://cityplanning.lacity.org/.
Contact information
Angela R. George, PE
Watershed Manager
Los Angeles River/Ballona Creek
Los Angeles County Department of Public Works
ageorge@dpw.lacounty.gov
Richard Gomez
Los Angeles County Department of Public Works
rgomez@dpw.lacounty.gov
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A.2 Alachua County, Florida: Preserving Suburban Lands to
Improve Water Quality Provides a Good Return on
Investment for the Community
Entity
Name: Alachua County, Environmental Protection Department (EPD) and Public Works
Department (PWD)
Population served: 250,000 (includes Gainesville, Florida)
Area: 900 square miles
Project highlights
Alachua County acquires, protects, and manages environmentally significant lands in order to
protect water resources, wildlife habitat, and natural areas suitable for resource-based recreation.
Key findings and program successes include:
> The county's comprehensive program with open space set-aside requirements, incentives
for low impact development (LID)/green infrastructure (GI), and intergovernmental
collaboration provides an effective path to sustainable stormwater management.
> Regression analysis on real estate sales shows that the increase in land values for properties
adjacent to open space more than offsets the property tax revenue loss associated with
acquiring open space for preservation.
> The development of a ranking system for acquisitions, with water quality a priority,
ensures that targeted goals are met.
> The program has won public support for land acquisition as evidenced by approval of bond
referendums for the program.
Background
Like many counties in Florida, Alachua County has grappled with the negative impacts of
suburbanization on natural systems, agriculture, and quality of life. In addition to the loss of
forests, farms, and natural areas, past land development practices have been linked to water
quality degradation throughout the county.
Since the mid-1990s, Alachua County also has experienced a sequence of extreme weather
events, including historic floods, droughts, wildfires, and hurricanes. Predictions for Alachua
County's climate change future suggest even greater extremes in weather conditions,
temperatures, and water levels.
The impacts of development are a top priority for Alachua County residents. Water quality and
other benefits associated with GI, e.g., recreation, ecosystem services, are seen as an important
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component of the county's economy and quality of life. Citizens' concerns for these issues have
driven the county's pursuit of GI programs.
To help mitigate the impacts of past land development, and to plan for expected growth and
other impacts, the county has developed a comprehensive LID/GI program based on three
different components: (1) LID/GI-based land development policies and regulations developed
through the county's Comprehensive Plan; (2) Alachua County Forever (ACF), a conservation
and land acquisition program; and (3) a unique governance structure designed to increase
interdepartmental collaboration to promote the adoption of LID/GI program elements.
Types of LID/GI solutions
The county's program includes development standards that require and provide incentives for the
use of GI on public and private lands, as well as preservation (through acquisition) of open space
lands to improve water quality and provide other benefits. LID/GI practices encouraged under
the development standards include enhanced stormwater pond designs, permeable pavement,
vegetated swales and rain gardens, cisterns and rain barrels, underground tanks, parking islands
and road medians with stormwater depressions and permeable parking areas.
The county has also implemented an educational program that includes advertising and the sale
of rain barrels at large home improvement stores. To date, the county has held three rain barrel
sale events that have had a high level of participation.
Program description
Alachua County's GI investment program relies on two major elements: the county's
Comprehensive Plan (including development standards) and ACF. The county has also
established a unique governance structure that emphasizes interdepartmental collaboration,
systems thinking, performance management, and public involvement.
The first program component, Alachua County's updated Comprehensive Plan, went into effect
in May, 2005. The plan is embedded with specific policies that require or provide incentives for
the establishment of GI assets on public and private properties through updated land
development regulations, e.g., a 20 percent open space set-aside common area requirement for
most new developments, with additional protection required for specially designated areas such
as wetlands, uplands, or special habitat areas. This program is administered through the County
Department of Growth Management.
A challenge to implementing the new development standards has been developers' inability to
obtain approval for GI approaches from state regional water management districts. In addition to
obtaining local permits, developers also must obtain permits from their regional district. Some
districts have not been approving the use of GI to meet stormwater management permit
requirements. On the public works side, the public works department (PWD) is concerned about
the maintenance needs associated with GI techniques.
The second component of the county's GI program is the ACF program, which is administered
by EPD. Through ACF, the county acquires, protects, and manages environmentally significant
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lands in order to protect water resources, wildlife habitat, and natural areas suitable for resource-
based recreation. All property acquired under ACF must be nominated for purchase by a citizen
of Alachua County. Since 2001, over 20,000 acres of lands valued highly for their environmental
and ecosystem benefits have been preserved through ACF and its partners.
A key objective of ACF is to maximize the leverage of local investment through acquisition and
management partnerships with municipalities, regional, state, and federal governments;
nonprofits; and private entities. Since 2001, two-thirds of the $82 million investment for public
acquisitions has been leveraged from outside sources. ACF has leveraged local funds by
applying to state and federal granting programs, acquiring lands in partnership with regional
water management districts, applying for transportation mitigation funds, working with nonprofit
organizations to provide bridge loans and partnership funds, and facilitating donations of land
and cash that meet both donors' charitable goals and ACF's conservation goals.
In deciding whether to purchase a particular parcel of land, county staff have developed a
ranking system based on key attributes for potential properties. Improved water quality is the
highest priority attribute. Public access, recreation, and habitat value are also key attributes used
to influence the selection of properties for purchase. Although the benefits associated with these
attributes are not monetized, they are ranked using an internal process developed by the
department. This process is intended to take the politics out of choosing properties for purchase.
ACF has been relatively well received by county residents. In both 2000 and 2008, residents
voted to raise taxes in order to help fund the program. Funding sources since then also have
included grants, partnership contributions, and donations from various sources.
Role of economic analysis
The objective of the economic analysis was to demonstrate the benefits of the ACF program. The
county evaluated how open-space lands affect surrounding home property values. The study was
commissioned in response to citizen concerns regarding the perceived loss of property tax
revenues due to county land acquisitions. The methods and results of this analysis are detailed in
the county's report, Open Space Proximity and Land Values.
Economic analysis method and results
Method
To estimate the impact of open space on nearby home values, the county performed regression
analysis on real estate sales based on data from the Alachua County Property Assessor. The
Assessor's office maintains extensive data on all parcels in the county, including land use,
buildings on the parcel, and sales information. The information for each parcel also includes the
size and type of any buildings, the age of the buildings, heating and air-conditioning status, and
the number of bedrooms and bathrooms. For each parcel, the county's consultant merged these
data with the following:
> The parcel's census block location, that provides data about the population density and
average income in the neighborhood in which the parcel is located.
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> The parcel's distance from the central business district in downtown Gainesville.
> The parcel's proximity to water or open space, which is based on geographic information
map layers for parks, open space, lakes, rivers, and creeks.
By combining these elements, the county was able to evaluate the effect on property sales prices
in relationship to factors such as parcel size, building size, building age, distance from
downtown, proximity to water, and proximity to open space.
Results: For most parcel types there is a strong correlation between parcel value and proximity to
parks and open space. Other factors that affect parcel value include the type of parcel,
e.g., single-family residential, vacant land, or condominiums, and location. For example, parcels
in the densely settled parts of Gainesville had a lower correlated property value associated with
proximity to open space than properties in less densely settled areas of the county.
Exhibit A.2.1 shows the results of the analysis (reported in 2004 U.S. dollars [2004 USD]).
Proximity to open space adds about $8,000 to $10,000 to parcel value; for parcels in medium-
density areas that touch open space and parcels of vacant land, the increase in value is as high as
$25,000 per parcel.
$30,000
$25,000
$20,000
$15,000
$10,000
$5,000 -
$-
$10,093
8,171
$7,988
High Density Medium Density Medium Density Low Density Vacant Land Condos
(Near open (Touching
space) open space)
Single Family Residential
Exhibit A.2.1. Increase in property value due to open space proximity, by land use and
population density of parcel neighborhood.
Source: Cape Ann Economics. 2004. Open Space Proximity and Land Values, Alachua County, FL.
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The county's analysis also revealed that locations adjacent to water almost always had higher
parcel values. As a result of this observation, proximity to water was treated as a separate factor
which had more weight.
Twelve thousand seven hundred parcels in the county are close enough to open space to show an
increase in value due to their proximity to water. The total impact on their value is just under
$150 million, which would result in additional property tax revenues of approximately $3.5
million per year.
It is important to note that the results shown above reflect information for all open-space lands
within the county rather than only those lands acquired under ACF. However, the county was
able to demonstrate that less than $100,000 per year in tax revenues is taken out of the tax base
each year because of the land acquisition program. This is because most of the land purchased is
zoned for agricultural use. Agricultural land has a special, much lower tax rate compared to other
property types.
Outcomes: As a result of this study, the county was able to gain further public support for the
ACF program by demonstrating a feasible alternative to growth based approaches. The county
believes that this analysis helped gain voter approval of the tax for the program in 2008.
Lessons learned and next steps
In hindsight, the county would have liked to focus its study on the effect of property values on
the open-space lands it acquired under ACF, rather than on the values of all properties in close
proximity to open-spaces in the county. The county has initiated a follow-up study to evaluate
this effect.
The county anticipates introducing a bond program to fund certain aspects of the program. To
garner support and promote a better understanding of GI, the county plans to provide information
to the public that demonstrates that GI has a good return on investment and that the net benefits
of GI are often higher than some traditional grey infrastructure practices. The county also would
like to conduct analyses to educate the public about the suite of benefits GI practices provide
such as carbon sequestration, improved quality of life, improved health, and enhanced water
resource values.
Education is an important issue in terms of the overall program, particularly for acceptance of the
LID/GI components of the development standards. The county believes it has a good program in
place but feels that it lacks sufficient examples and data to prove that the program effectively
reduces stormwater impacts and provides economic and social benefits. The county also noted
that understanding what the public is willing to accept in terms of LID/GI is an important aspect
of designing an effective program, given that location, cultural difference and housing density
often affect public acceptance of what is acceptable or desirable in terms of development and
growth.
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Related links
Similar programs and analyses
In the Charles River watershed, located near Boston, Massachusetts, the Army Corps of
Engineers has preserved wetlands and open spaces to store excess floodwaters and reduce
damage on the upper and middle portions of the Charles River. Since 1977, the Army Corps of
Engineers has been purchasing land and acquiring easements, prioritizing the parcels by location,
storage capacity, and threat of development. For more information, see
http://www.nae.usace.armv.mil/Missions/CivilWorks/FloodRiskManagement/Massachusetts/Cha
rlesRiverNVS.aspx.
As described in the Philadelphia case study, the Philadelphia Water Department also evaluated
the potential impact of its proposed LID/GI program on surrounding property values.
Key sources
For more information on the development review standards, visit the Alachua County
Environmental Protection Land Development Regulations page:
http://www.alachuacounty.us/Depts/EPD/NaturalResources/Pages/LandDevelopmentRegulations
.aspx
For more information on ACF, visit the Alachua County Environmental Protection Land
Conservation page:
http://www.alachuacountv.us/Depts/EPD/LandConservation/Pages/LandConservation.aspx.
To view the full property values report, Open Space Proximity and Land Value., visit
http://www.alachuacounty.us/Depts/EPD/Documents/Land/Files/Alachua%20Write-
up%20Jul%2004.pdf
To learn more about the ranking process for proposed land acquisitions, see the Alachua County
Environmental Protection ACF Site Evaluation Scoring Matrix and criteria:
http://www.alachuacounty.us/Depts/EPD/Documents/Land/site_scoring_criteria.pdf
The University of Florida Program for Resource Efficient Communities assisted Alachua County
in promoting LID/GI and developing land development regulations and enhanced stormwater
designs. For more information on this program, go to http://buildgreen.ufl.edu/.
Contact information
Ramesh Buch, Program Manager
Alachua County Forever Land Conservation Program
Alachua County Environmental Protection Department
201 SE 2nd Avenue, Suite 201
Gainesville, FL 32601
rpbuch@alachuacounty.us
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A.3 Kane County, Illinois, Blackberry Creek Watershed: Finding
that Environmentally Sensitive Land Development Is Also
Fiscally Responsible
Entity
Name: Kane County, Illinois
Population served: 511,892
Area: The Blackberry Creek watershed is in south central Kane County and north central
Kendall County and is approximately 73 square miles in size. It includes portions of seven
municipalities. The focus of this case study is on the 58 square mile area of Kane County portion
of the watershed which is an outer-suburb of Chicago.
Project highlights
> Modeling performed by Kane County as part of the Blackberry Creek Watershed
Alternative Futures Analysis was conducted to evaluate alternative land development
scenarios. The results of the modeling indicated that with conventional development, the
hydrologic, i.e., flooding, physical, i.e., streambank erosion, and biological, i.e., water
quality and aquatic habitat conditions in the streams and wetlands of Blackberry Creek
would likely degrade as the watershed continued to be urbanized. Conversely, these
conditions would likely improve as conservation plans and practices are implemented.
> To further explore these findings, Kane County conducted a fiscal impact analysis to
compare the effect of conventional versus conservation-based development on public costs
and revenues, i.e., revenues and costs to the governmental units providing services to the
development.
> The fiscal impact analysis found that between the two alternatives analyzed, conservation
development imposes a lower net public cost based on analysis that examined population-
based and land-based fiscal impacts.
Background
In July 1996, the Blackberry Creek watershed experienced significant flooding as a result of
record rainfalls. This flooding prompted formation of the Blackberry Creek Watershed Resource
Planning Committee and preparation of the Blackberry Creek Water shed Management Plan.
After the plan was completed in 1999, it was adopted by Kane and Kendall counties and most of
the municipalities within the Blackberry Creek watershed. A significant focus of the plan was the
prevention of further flooding and degradation of stream and wetland resources due to future
urbanization of the watershed. The plan addressed ways to resolve the flooding issues and other
areas of concern such as water quality, biological integrity, and streambank erosion.
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The existence of the comprehensive and environmentally focused Blackberry Creek Watershed
Management Plan, the expected growth in central Kane County, and the region's flooding
concerns was a positive factor influencing the decision by the U.S. Environmental Protection
Agency (EPA) and the Illinois Department of Natural Resources to fund the study Blackberry
Creek Watershed Alternative Futures Analysis The primary purpose of this analysis, completed
in September 2003, was to evaluate the hydrological, physical, and biological impacts associated
with potential "alternative futures" for land development in the Blackberry Creek watershed. The
intent was to:
1. Investigate what would occur if current land use plans, development codes, and
conventional development practices were followed.
2. Determine what might occur if conservation-^?,^ site design and ecologically sensitive
land use planning were used.
Hydrological modeling was performed to assess biological health and aquatic habitat protection
under each scenario, as well as impacts on flooding and streambank erosion. Kane County served
as the lead agency for the analysis. The results of the Alternative Futures Analyses revealed that
without the implementation of conservation-based development practices the watershed would
continue to degrade.
To further explore these findings, Kane County (in partnership with EPA) initiated the
Blackberry Creek Watershed Alternative Futures Fiscal Impact Study, which is the focus of this
case study. The Fiscal Impact Study was conducted to explore the relationship between
environmentally sensitive land development and fiscally responsible land development. The
study analyzed the fiscal impacts of planned development within the Blackberry Creek
watershed under the conventional and conservation-based development scenarios included in the
Alternatives Futures Analysis. The purpose of a fiscal impact analysis is to estimate the impact of
a development or a land use change on the costs and revenues of governmental units providing
services to the development. The analysis is generally based on the fiscal characteristics of the
community in terms of revenues, expenditures, and land values and the characteristics of the
development or land use changes including the type of land uses and distance from central
facilities. The analysis enables local governments to estimate the difference between the costs of
providing services to a new development and the revenues—taxes and user fees, for example—
that the development will generate.
LID/GI solutions
A variety of storm water and landscaping BMPs were used in the design and development of the
conservation-based development scenario included in the Alternative Futures Analysis. Many of
these BMPs now have been incorporated into the County's Stormwater Management Ordinance.
Also examined in the Alternative Futures Analysis were several planning/zoning BMPs that can
be used to facilitate many of the stormwater BMPs.
Stormwater BMPs included in the conservation development scenario include bioswales, filter
strips, green roofs, naturalized detention basins and drainageways, porous pavement, rain
barrels/cisterns, rainwater gardens, vegetated swales, and native landscaping.
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Planning and zoning BMPs included in the conservation development scenario include:
> Conservation development practices. These practices such as environmental site planning
and design help preserve existing natural areas, enhance wildlife habitat, conserve energy,
and improve transportation efficiency, largely through the use of natural drainage ways and
onsite detention practices.
> Impervious area reduction. Impervious surfaces are reduced by narrowing streets, reducing
street lengths in lower-density residential neighborhoods, the use of shared driveways and
parking areas and the design of roads, walkways, and trails to minimize impervious surface
area and provide multi-modal transportation routes.
> Open space/naturalgreenways. This practice is used to preserve and connect significant
natural features for aesthetic, recreational, and/or alternative transportation uses.
Program description
Since the publication of the Alternative Futures Analysis and corresponding Fiscal Impact Study.,
Kane County has continued to take additional actions to reduce the negative impacts of
stormwater and improve the quality of life in the Blackberry Creek watershed, e.g., the
development of a stormwater ordinance and recommendations for watershed zoning code
analysis and Ordinance Language.
The county's stormwater ordinance establishes a set of minimum standards for all new
development within the county and associated municipal boundaries. Under the ordinance,
3/4-inch rainfall or its equivalent must be retained or routed to extended detention facilities from
the directly connected impervious surfaces created by the new development. All existing on-site
wetlands must also be protected with buffers of varying length as determined by the quality and
size of the wetlands. The ordinance also requires the establishment of special services areas
(SSAs) for new developments for the purpose of funding the maintenance of stormwater
management BMPs. The SSAs establish a tax that is paid by all residents in the development.
This provides enough funds for the county to hire an outside contractor to maintain the BMPs.
In addition to the county-wide ordinance, Kane County also initiated an ordinance review to
provide suggested ordinance revisions to each of the municipalities and counties within the
watershed (see the Blackberry Creek Zoning Code Analysis and Ordinance Language
Recommendations). Particular attention was paid to zoning and subdivision ordinances, and
specifically those codes that pertain to the management of stormwater runoff. The ordinance
review project resulted in the identification of potential changes to standards and codes for
elements of development outside the typical realm and authority of the stormwater ordinance.
For example, subdivision and zoning ordinances are used to control land use, whereas the
stormwater ordinance does not address land use but rather how land is developed. One aspect of
the ordinance review project was to develop language that communities could include in their
subdivision and zoning ordinances to encourage land uses that will decrease runoff impacts.
Although the economic downturn has affected development in Kane County and the rate of
LID/GI practice implementation, the county continues to plan for growth in an environmentally
responsible manner. To date, the most common type of LID/GI practice that has been
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implemented is naturalized detention basins—wetland systems with native vegetation and native
vegetation on side slopes. The county also has successfully implemented several permeable
pavement projects, narrow street designs, demonstration projects at the City of Aurora school,
and a cluster development in Sugar Grove.
In addition to the Blackberry Creek Watershed Management Plan, which is being updated, the
county is participating in the development and updating of watershed management plans for
Person and Otter Creek, Sleepy and Jelkes Creek, and Tyler Creek. The county is using the
Alternative Futures Analysis as a reference for these plans.
Role of economic analysis
The primary role of the Fiscal Impact Study was to gain support from the communities within
Kane County for the BMPs included in the Alternative Futures Analysis. These BMPS were
subsequently integrated into the county's stormwater ordinance/land development standards. The
analysis also has served to provide input to the county's 2030 Land Resource Management Plan
and as a reference document/template for Kane County to be used to enhance coordination
among municipalities and the development of integrated stormwater management strategies.
Economic analysis method and results
Method: In 2004 Kane County conducted the Blackberry Creek Watershed Alternative Futures
Fiscal Impact Study., which compared the two development scenarios—conventional
development and conservation development—described in the Alternatives Futures Analysis.
Exhibit A.3.1 provides a summary of these scenarios. The basic hypothesis behind this study is
that there is a neutral or positive relationship between environmentally sensitive land
development and fiscally responsible land development.
Exhibit A.3.1. Alternative development scenarios used in alternative futures analysis
Conventional development alternative. This scenario was designed to examine the following land uses: Rural
Estate Residential, Large-Lot Single-Family Residential, and Commercial. Average lot sizes for Rural Estate
Residential and Large-Lot Residential are 58,200 and 12,500 square feet, respectively. For the Large-Lot
Residential category, the development pattern includes conventional rights-of-way and stormwater controls, as
well as infrastructure improvements such as public water supplies, sanitary sewers, storm sewers, sidewalks, and
street and sidewalk designs.
Conservation development alternative. This scenario was used to examine Rural Residential, Moderate-
Density Residential, and Commercial land uses. Average lot sizes for Rural Residential and Moderate-Density
Residential are 21,385 and 7,685 square feet, respectively. The Conservation scenario represents a form of
development in which the design is modified based on landscape topography and natural drainage patterns to
utilize the natural infiltrative capacity of the landscape as much as possible. This design flexibility allows for a
more concise development pattern or development footprint and leaves more land in open space because
buildings are clustered. Using this approach also can reduce infrastructure such as pavement areas, curbs,
gutters and other right-of-way impervious surfaces.
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As a first step, Kane County used a land capacity model to evaluate the municipal infrastructure
and services requirements associated with the conventional and conservation-based land
development scenarios. This model was used to examine the impacts of local land development
regulations and land use designations under each development scenario and convert these
impacts into data that could be used to determine the fiscal impacts of land use decisions in the
Fiscal Impact Study. For example, under a given development scenario, a community might
require 10,000 square feet of lot area for a detached, single-family residence. However, the land
area needed to support that residence includes additional land areas for streets, stormwater
control, and other desired amenities.
The county used the outputs of the land capacity models, to run the Fiscal Impact Land Use
Model (FILUM) (Dalstrom 2000) and analyze the overall relationship between county revenues
and expenditures likely to occur over time under the two development alternatives. The analysis
was applied to the entire unincorporated and undeveloped portion of the Blackberry Creek
watershed located in the planning areas of the component communities; that area contains about
18,000 acres.
The analysis first examined revenues and costs as described below. These revenues and
expenditures were then compared to evaluate the net public cost associated with the alternative
development scenarios.
Revenues associated with development scenarios: The county used the FILUM model to estimate
revenues associated with each development scenario, including:
> Real estate taxes.
> Sales tax distributions.
> Motor fuel tax rebates.
> State income tax rebates.
> Development impact fees.
> Building permit fees.
To estimate property tax revenues, the county first determined the fair market value (FMV) of
future development based on a number of assumptions. The assessed value of a property was
then determined based on the local assessment factor. The assessed value of a property is the
basis upon which its tax liability is computed. In Kane County, developed residential,
commercial, and industrial property is assessed at one-third of its FMV.
In Illinois, sales tax distributions are based on "point of sale." Thus, projected sales tax receipts
for Kane County are based on the sales potential associated with additional retail commercial
space under the two development scenarios, and not on assumptions regarding the retail and
service expenditures of new resident households. Further, the county applied a 20 percent
"redistribution factor" that accounts for the overlap of new retail commercial operations with
existing operations in the community.
Most other revenues were projected on the basis of population and dwelling units. For example,
Illinois municipalities receive revenues from motor fuel tax and state income tax on a per capita
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basis, whereas building permit fees and development impact fees are usually received on a per
dwelling unit basis.
Expenditures associated with new development: To calculate expenditures (i.e., costs of
providing services to the new development such as solid waste collection or street maintenance),
the county used average cost methods to assign operational and capital costs to both development
scenarios. Specifically, the county used a combination of costs per developed acre and costs per
capita. This approach applies the ratio of developed land in the three principal private sector land
use categories (residential, commercial, and industrial) to the budget to derive an assignment of
municipal costs per developed acre. The resulting residential component of the budget is then
divided by the population to derive a cost per capita.
Results: The study found that the conservation development alternative imposes a lower public
cost than the conventional alternative. Exhibit A.3.2 provides a graphic comparison of the fiscal
impacts of the conventional and conservation-based development scenarios. The vertical axis
shows the net public cost, or the difference in expenditures and revenues under the two
development scenarios.
ouu.uuv
400,000
0
-400,000
-800,000
•1,200,000
-1,600,000
•2,000,000
^ ^5^- ±^
n n ^^ ^ ^^"*
*V D
0 D
D ^
n
n
123456789 10
Years
-^Conservation
D Conventional
Exhibit A.3.2. Net public costs associated with conventional and conservation-based
development scenarios.
As shown in Exhibit A.3.2, both the conventional and conservation-based scenarios result in a
negative fiscal impact balance over the 10-year period. This result is not surprising given a
development projection dominated by residential land uses (which are typically more expensive
to maintain/provide services compared to commercial and industrial properties). However, the
extent of the negative impact is reduced significantly under the conservation scenario. The
downward trend of the projections results from the gradual reduction of revenue from one-time
sources such as building permit fees and development impact fees combined with the cumulative
nature of service costs.
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The fiscal benefits of the conservation form of development result from the fact that reduced
resources are required to support service delivery to, and infrastructure for, natural areas. In a
given study area, it is likely that the extent of the benefit could vary considerably, whereas the
existence of the benefit would remain constant. The county also found that to realize the
potential public cost savings to the maximum extent, the clustering of development under the
conservation scenario should be focused in a compact and contiguous form, locating
development at the immediate periphery of the community wherever possible.
Outcomes: In partnership with the Conservation Foundation, Kane County presented the Fiscal
Impact Analysis to all 26 communities within Kane County to gain support for conservation-
based development and the stormwater ordinance. The fiscal impact analysis served as evidence
that municipalities can save money by adopting many of the conservation-based approaches. In
general, municipalities were supportive of and responsive to the proposed land use changes.
The county believes that since the Alternative Futures Analysis was published, there has been a
real shift in support of conservation-based approaches. Communities and residents are beginning
to understand how using these types of systems can improve water quality, reduce flooding, and
help aquatics.
The Blackberry Creek Alternative Futures Analysis is still used and referred to by the county,
and it will serve as an important input into the revised Blackberry Creek Watershed Plan
(required by EPA for funding under section 319 of the Clean Water Act). Although the cost data
used in the Fiscal Impact Study may have changed since the study was conducted, the overall
results remain relatively unchanged. The studies have resulted in positive support for the
stormwater ordinance.
Lessons learned and what's next
The County considered conducting a fiscal impact analysis that would assess costs to developers,
with the expectation that the costs associated with conservation-based systems would be lower
than those associated with conventional systems and would result in higher property values
(meaning higher profits). However, the county did not have sufficient resources to conduct such
a study.
Kane County believes that one reason its communities have been supportive is that the
alternative futures analysis, stormwater ordinance, and fiscal impact analysis were clearly
communicated by a well-respected community member.
The county has also learned that it is necessary to clearly communicate with developers about
new conservation requirements. Up-front communication encourages developers to comply with
these changes.
Maintenance of conservation-based techniques has been an issue for the county. Once the
developers install the recommended BMPs, they do not believe they are responsible for
maintenance, and in many cases the community is not able keep up with the maintenance
(e.g., especially if it has no organized body to take charge). To deal with this problem, the county
initiated the SSA tax (described above) to fund the maintenance of stormwater management
BMPs. Another maintenance issue involves educating the public about how to help keep
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conservation areas healthy (e.g., the public should not mow open-space areas intended to serve
as prairie habitat or toss yard waste into wetland areas).
Related links
Kane County Stormwater Management. More information can be found at
http://www.co.kane.il.us/kcstorm/.
Key sources
Conservation Design Forum. 2003. Blackberry Creek Watershed Alternative Futures Analysis.
Prepared for Kane County, Illinois. September. Available:
http://www.co.kane.il.us/kcstorm/blackberry/FinalReport.pdf
Conservation Design Forum. 2004. Blackberry Creek Watershed—Zoning Code Analysis and
Ordinance Language Recommendations. Prepared for Kane County, Illinois. April. Available:
http://www.co.kane.il.us/kcstorm/blackberry/zoning/FinalReport.pdf
Dahlstrom, R.K. 2000. Linking the Comprehensive Land Use Plan and Fiscal Impact Analysis.
Mid-continent Regional Science Association.
Dahlstrom, R.K., R. Rima, and T. Wittenauer. 2004. Blackberry Creek Watershed Alternative
Futures Fiscal Impact Study, Kane County, Illinois. Northern Illinois University Center for
Government Studies. Prepared for Kane County, Illinois. March. Available:
http://www.co.kane.il.us/kcstorm/blackberry/FiscalImpactStudy.pdf
Kane County, Illinois. 1999. Blackberry Creek Water shed Management Plan.
Kane County Government Center. 2004. 2030 Land Resource Management Plan: Planning for
Safe, Healthy and Livable Communities. Kane County Regional Planning Commission, Kane
County Development Department.
Contact information
Ken Anderson, Manager
Kane County Subdivision & Special Projects Division
719 S. Batavia Avenue
Geneva, IL 60134
andersonken@co.kane.il.us
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A.4 West Union, Iowa: Long-Term Cost Savings Plus
Environmental and Social Benefits Envisioned in Rural
Green Streets Pilot Project
Entity
Name: City of West Union, Iowa, in partnership with the Iowa Department of Economic
Development (IDED)
Population served: 2,500
Area: Project area includes the renovation of six downtown blocks
Project highlights
A main street "green street" is planned to revitalize a rural community's downtown features:
> Life-cycle cost analysis shows a cost savings associated with the use of a permeable
pavement system when compared to the use of conventional asphalt. Payback begins at
year 15.
> Other benefits include reduced flooding and water quality improvement from permeable
pavements, biofiltration, and rain gardens.
> The results of economic analyses played an important role in gaining support and financing
for the project.
> The green street proj ect was part of a larger redevelopment plan for the downtown that, for
example, included evaluation of a geothermal district heating system for buildings that
could result in long-term savings.
Background
West Union, Iowa, has developed an integrated approach to community sustainability and
livability through the Iowa Green Streets Pilot Project, which includes the complete renovation
of six downtown blocks in West Union. The project will replace aging water, storm, and sanitary
sewer infrastructure through the use of various LID/GI components. Primary objectives of the
project include citizen safety, replacing aging infrastructure, improving water quality and habitat
in a nearby trout stream, and reducing flooding in the downtown area. The project also is
intended to serve as a catalyst for future investment in the historic downtown area.
Types of LID/GI solutions
The Green Streets Pilot Project involves a number of LID/GI techniques, including a permeable
paver system for the roadway and sidewalks, rain gardens and biofiltration areas.
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In addition to the LID/GI measures specifically related to stormwater management, the pilot
project also includes a number of components intended to improve community livability and
sustainability. These elements, which include the use of energy-efficient lighting, a district
geothermal heating and cooling system, pedestrian-friendly crosswalks, and building energy
performance improvements illustrate the need to take an integrated benefits approach to
incorporation of innovative stormwater solutions into larger capital improvement projects.
Program description
In response to the need to replace aging infrastructure and reduce the risk of flooding in the
downtown area, West Union had initially designed a very basic, traditional grey infrastructure
stormwater project. At the same time, IDED's Downtown Resource Center (Main Street Iowa
Program) had selected West Union as a model pilot community for demonstrating a holistic
approach to implementing a sustainable green streets initiative. West Union was selected on the
basis of a number of criteria, including its participation in the Main Street Iowa community, the
existence of affordable housing projects in West Union, and its existing streetscape project plan
that included the replacement of its aging water infrastructure. IDED provided technical
assistance to help integrate these two projects.
This project began with a visioning workshop in October 2007, when IDED completed a
technical assistance visit to advise West Union about the potential for multipurpose pedestrian-
scale streetscape improvements. The result of the initial visioning and the subsequent conceptual
and schematic planning was a streetscape master plan. The master plan includes many
innovative, sustainable design strategies, such as permeable pavements, rain gardens, pedestrian
crosswalk treatments, and energy-efficient lighting.
When completed, the project will be able to completely absorb runoff from a 10- to 20-year
storm event. Additional project benefits include reduced flooding in the downtown area and
improved recreation and ecosystem habitat.
It has been difficult for West Union, a very small town, to garner sufficient resources to complete
the initial planning and design, including putting together a financing package, e.g., researching
funding entities, submitting proposals, combining funding from several types of sources). To
address these issues, IDED has provided assistance with up-front planning and has helped West
Union to hire a grant application writer. The local Main Street organization, local businesses, and
the city also have contributed to funding for the contacted grant writer.
The cost of the project has been a concern among members of the public and other stakeholders.
The initial stormwater project the city had designed was estimated to cost between $3 million
and $4 million. After the project was linked to downtown revitalization and focused more toward
GI, the estimated cost increased to about $10.5 million, plus a $1 million contingency. Currently,
about $8.5 million has been obtained through various sources, with the city paying
approximately $3 million. Thus, the city is not paying any more than it would have for the
original project.
Funding has been secured through the local and county governments, local organizations, IDED,
the Iowa Department of Transportation, the Iowa Department of Cultural Affairs, the Iowa
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Department of Natural Resources, the Iowa Department of Agriculture and Land Stewardship,
and the U.S. Department of Agriculture (which provided funding for the district heating/cooling
and ice melt feasibility study). The city is also investigating the use of tax-increment financing
(TIP) to help fund the project. TIP is a financing method that uses future gains in taxes to finance
current improvements (which theoretically will create the conditions for those future gains).
Role of economic analysis
The city has completed an economic analysis of the project to evaluate net benefits of the LID-
based streetscape design compared to traditional infrastructure. Included in the analysis is a life-
cycle analysis of permeable pavement costs versus traditional pavement costs, as well as an
evaluation of savings associated with reduced road maintenance during snow or ice events,
e.g., avoided costs as a result of reduced salting and plowing. Overall, these analyses were used
to garner support for the project, guide decision-making, and obtain funding through various
sources, e.g., federal agencies and grant programs.
Economic analysis method and results
Method. The city compared the life-cycle costs (including capital and O&M costs) associated
with the use of a permeable paver system in the downtown area and those associated with using
traditional bituminous or Portland cement concrete pavement. Cumulative costs were analyzed
over a 57-year project period. As part of this analysis, the city recognized, but did not quantify,
the benefits associated with porous pavement relative to traditional pavement, such as improved
water quality, increased stream health and appearance, reduced storm sewer infrastructure and
maintenance, improved pavement surface temperatures, i.e., retained heat, and improved street
appearance. These benefits were not a driving force behind project implementation, but they
helped to confirm the sustainability aspects of the project.
Project partners hope to document the benefits of the project on the trout stream that drains the
downtown area. The Iowa Department of Natural Resources and Upper Iowa University have
gathered pre-construction data on the stream in order to allow for a comparison to post-project
conditions. The impacts and indicators measured include total pollutants, water temperature, and
stormwater volume leaving the project area.
IDED and West Union would like to further research the impact of the permeable paver system
on maintaining warmer temperatures on pavement surfaces in the winter, which could help to
reduce the need for associated costs of snow plowing. These potential cost savings have not been
evaluated, in part because the temperature effects are not yet fully understood.
Results: Results of the life-cycle analysis of different pavement types show that although the use
of porous pavement will initially be more expensive, the lower maintenance and repair costs
associated with cold weather and drainage will result in cost savings in the long run. The study
indicates that the city would begin to realize these cost savings by year 15 of the project.
Estimated cumulative savings over the 57-year analysis period amount to close to $2.5 million.
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Outcomes: Based in part on the economic analysis of the project, IDED and West Union have
been able to obtain support and secure additional funding for parts of the project from outside
sources. Without this funding, the project most likely would have been implemented using the
grey infrastructure approach that was originally planned.
Not all elements evaluated were selected. A geothermal street deicing system extending from the
building geothermal system was evaluated, but ultimately not selected for implementation. An
advantage of geothermal street deicing would have been a reduction in salts applied, reducing
both costs and salt loading to nearby streams.
Lessons learned and next steps
A key challenge in putting together the economic analysis was being able to compare up-front
costs and long-term costs for conventional practices with those for more sustainable practices.
Urban-based analyses do not transfer very well to smaller, rural community situations. For
example, for the economic analysis, the capital and O&M costs of the permeable paver system
were compared to those associated with traditional types of pavement. In West Union, however,
there is no regular maintenance plan for the infrastructure that is currently in place. Thus, the city
will not realize cost savings if it is not maintaining the roads in the first place.
In addition, in terms of evaluating costs, there is a lack of existing data for newer innovative
practices, and a number of assumptions must be made. West Union and IDED worked with the
best information available, based on the local experience of the contracted engineering firm and
the city's public works staff.
In terms of the overall project, one of the most significant barriers to implementation has been
finding the time, expertise, and funding for planning and analysis. These resources are not often
a priority or available in small communities. In addition, it is hard for small communities to find
sufficient funding to cover capital costs. Even though communities might save in the long run by
implementing LID/ GI measures, they also can be discouraged by the higher up-front capital
costs associated with many LID/GI measures.
Finally, local support is crucial, but engaging the public can be difficult. It is important to work
and communicate with the public early and often to prevent the spread of misinformation.
The next steps in implementing the project are to secure the remainder of the funding needed and
to start construction of the geothermal component. The downtown street construction is nearly
complete, and the district geothermal system component is scheduled to begin operation in 2013.
Related links
Similar programs and analyses
Both Seattle, Washington, and Ventura, California, have implemented comprehensive green
street programs. For more information on Seattle's Green Streets program, see
http://www.seattle.gov/util/MyServices/DrainageSewer/Projects/GreenStormwaterInfrastructure/
CompletedGSIProiects/StreetEdgeAlternatives/index.htm.
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For information on Ventura's LID and Green Streets programs, see
http://www.venturariver.org/2008/07/ventura-adopts-green-streets-policy.html and
http://www.surfrider.org/ventura/reports/Solving%20the%20Urban%20Runoff%20Problem%20-
%20Ventura.pdf.
Key sources
For more information on the West Union Green Street Pilot Project, see "A Sustainable Vision
for West Union: Integrated Green Infrastructure to Achieve a Renaissance of West Union's
Downtown District and Neighborhoods" at
http://www.westunion.com/uploads/PDF_File_67184288.pdf.
For more information on the West Union District Geothermal Project, see "West Union, Iowa:
Small Town, Big Vision" at http://www.westunion.com/uploads/PDF_File_l7418597.pdf.
Contact information
Jeff Geerts, Special Project Manager
Iowa Department of Economic Development
200 E. Grand Ave.
Des Moines, IA 50309
ieff.geerts@iowalifechanging.com
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A.5 Lenexa, Kansas: Demonstrating Cost Savings Associated
with New LID/GI Development Standards
Entity
Name: City of Lenexa Public Works Department, Watershed Division
Population served: 47,000
Area: 34 square miles
Project highlights
As part of its Rain to Recreation program, the City of Lenexa adopted LID/GI-oriented
development standards and a systems development charge for new development:
> Prior to adoption of the standards and fee, the city analyzed potential impacts for different
types of developments. The analysis showed substantial cost savings associated with the
implementation of LID/GI-oriented BMPs compared to traditional development
approaches.
^ As a result of the analysis, the Lenexa City Council adopted the development standards and
an accompanying BMP manual. In addition, the city gained developer support for the
adoption of the ordinance and the systems development fee.
Background
The City of Lenexa encompasses a 34-square-mile area, approximately two-thirds of which is
experiencing development pressure. The city is located just outside the metropolitan Kansas City
area. In 2000, to accommodate rapid growth, the city developed a citizen-driven Watershed
Management Master Plan that formed the basis of what is now the comprehensive Gl-based
stormwater management program, Rain to Recreation. The objectives of Rain to Recreation are
to reduce flooding, improve water quality and habitat, and provide recreational opportunities.
Types of LID/GI solutions
The Rain to Recreation program consists of both regulatory and non-regulatory approaches to
stormwater management. The program's non-regulatory measures include major capital projects,
e.g., lakes that serve as regional retention facilities, land acquisition, and stream restoration
projects, as well as LID/GI-based components such as green street improvements such as,
bioretention cells and native vegetation plantings, rain gardens, and wetlands. The city also
conducts outreach and education activities. Specific regulatory measures include protection of
priority natural resource areas, a stream setback ordinance, and LID/GI standards/requirements
for new development.
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Program description
The Watershed Management Master Plan provided initial direction for the city's Rain to
Recreation program in the form of policies, practices, and projects. The plan resulted in the
construction of five regional retention facilities, lakes and numerous joint use detention facilities
that provide passive recreational opportunities and, in some areas, serve as informal sports fields.
Other elements of the plan include the creation of multipurpose regional stormwater facilities to
provide flood protection and additional active and passive recreational opportunities.
Upon completion of the activities identified in the plan, the city continued to work toward
sustainable stormwater management under Rain to Recreation. In March 2002 the city adopted a
Stream Setback Ordinance. Today, LID/GI-based components of the program include stream
restoration, e.g., streambank laybacks, native vegetation planting, urban stream restoration, green
street improvements, rain gardens, bioretention areas, and wetlands.
In 2006 the city formed a "green crew" to implement stream restoration and GI projects in a
more cost-effective way. As a result, the city has been able to complete a large majority of its
stream restoration projects which ranged from $750,000 to several million dollars per project in-
house.
In addition, in 2004 the City Council adopted new LID/GI development standards and an
accompanying Manual of Best Management Practices for Stormwater Quality (BMP Manual).
The development standards include decentralized LID/GI approaches such as native planting,
bioswales, permeable pavement, bioretention cells, wet ponds, and open space. The BMP manual
was developed through a cooperative effort led by the Kansas City Metro Chapter of the
American Public Works Association (APWA), in coordination with the Mid-American Regional
Council, and a host of municipalities within the Kansas City region. The city continues to work
with the development interests and recently held a BMP workshop for construction industry
professionals.
In conjunction with the new development standards, and as a result of a multi-stakeholder
process that included the Lenexa Economic Development Council and the Homebuilders
Association, the City Council also implemented a systems development charge. This is a one-
time capital fee implemented to support the funding of programs necessary to manage runoff
volumes associated with new development. The fee is based on impervious area and amounted to
$956 per established equivalent dwelling unit (EDU) (2,750 square feet) in 2010; the fee is tied
to the Consumer Price Index. Revenue from the fee has not been as large as expected because
growth in the area has slowed.
In addition to the systems development fee, the city's program is funded through a variety of
sources, including a temporary 1/8 of a cent sales tax that was approved by city residents in 1999
and 2004 by a 78 percent margin) and a stormwater utility fee for all residential and commercial
parcels based on the amount of impervious surface. Continued grants from state and federal
sources, such as the Clean Water Act Section 319 Nonpoint Source monies for park construction
and Surface Transportation Project funding for roadway projects, have also helped to fund
capital and demonstration projects. Monies appropriated through the American Reinvestment
and Recovery Act and administered through the Clean Water State Revolving Fund was used to
supplement a large stream restoration and revitalization project in the city center.
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Role of economic analysis
To evaluate the impacts of the system development charge and the development standards prior
to their adoption, the city analyzed the feasibility of BMP implementation for different types of
developments. This analysis includes an evaluation of cost savings associated with
implementation of the new LID-/GI-oriented BMPs compared to traditional development
approaches. The results of this analysis were then compared to the total cost of the proposed
systems development charge at each site. Results were used to justify adoption of the new
standards and fee.
Economic analysis method and results
Method. The city analyzed the feasibility of implementing the BMPs described in the manual
adopted as part of the development standards. The analysis used existing Lenexa site plans for
proposed single-family residential, multi-family residential, commercial/retail, and
warehouse/office developments.
BMPs that would meet specified water quality goals were selected for each development,
e.g., LID/GI techniques such as native planting, permeable pavement, and bioswales. Next, the
capital costs associated with BMP construction were estimated. Value engineering approaches
were then applied to identify construction items that were originally considered that could be
replaced or eliminated due to the inclusion of LID/GI BMPs. Resulting cost savings were
determined, e.g., cost savings due to reduced earthwork and/or pavement needed because of the
addition of LID/GI practices.
The benefits associated with the availability of additional developable land that was "recovered"
by reducing stormwater detention facilities were also included in the calculations. For example,
increased developable land allows commercial developers to build more retail space. For the
commercial example, the benefit of this additional space was estimated to be $6 per square foot.
Finally, the systems development charge was calculated for each proposed development and the
net savings, i.e., the difference between the anticipated cost reductions associated with BMP
implementation and increase in costs due to the system development fee, were determined. This
analysis shows how the implementation of BMPs can help to offset the proposed fee.
Results: Exhibit A.5.1 demonstrates the net savings associated with implementation of selected
BMPs and application of the systems development charge to the existing development types.
Both the commercial/retail and warehouse/office examples demonstrated significant savings
associated with the application of BMPs. The multi-family example demonstrated that LID/GI
BMPs could be applied to multi-family developments. Single-family homeowners, in the
example chosen for this analysis, would see an increase of $314 per home versus the full cost of
the systems development charge ($956) if the developer applied stormwater quality LID/GI
BMPs and reduced impervious surface in the residential development.
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Exhibit A.5.1. Net impact of systems development fee and implementation of Gl BMPs
Increase in costs Cost reductions
due to system associated with BMP
Development type EDUs development fee implementation3 Net impact
Single family
Multi-family
Commercial/retail
Warehouse/office
221
100
57
356
$187,850
$85,000
$48,450
$302,600
$118,420
$89,043
$168,898
$317,483
-$69,430
$4,043
$120,448
$14,883
a. As noted above, BMP construction cost savings/benefits include cost savings associated with Gl implementation compared to
traditional infrastructure and the benefits associated with additional developable land.
In addition, Lenexa has found that stream setbacks and preservation through land acquisition
have been the most cost-effective means of controlling stormwater through Gl. Bioretention
continues to be very expensive compared to rain gardens, and the city is leaning toward the
implementation of more rain gardens.
Outcomes: The city was able to consistently demonstrate the savings of ranging from tens to
hundreds of thousands of dollars in site work and infrastructure costs associated with the
application of LID/GI and stormwater management BMPs. As a result, the Lenexa City Council
adopted the new stormwater regulations and the APWA BMP manual on April 20, 2004, the first
municipality in the Kansas City metropolitan area to do so. In addition, the city gained developer
support for the adoption of the ordinance and a systems development fee, which was also
adopted.
Lessons learned and next steps
Lenexa's Rain to Recreation program is highly supported by the city's residents and serves as a
model for cities throughout the country. Recent (2009) polling data show citizen satisfaction with
the Public Works Department-Stormwater Program at 84 percent. This satisfaction is largely due
the fact that the city has been open and transparent and included stakeholders at all levels of
decision-making.
As the program has progressed, compliance issues have driven expenditures and policy
development. The City Council is now interested in the life-cycle costs associated with these
efforts and would like more information on these costs in the future.
Financing the program may become more of a challenge for the city when the temporary sales
taxes expire. Compounding matters, the city is responsible for maintaining and replacing more
than 50 miles of corrugated metal pipe that is part of the city's stormwater management system.
Paying for LID/GI and necessary grey infrastructure BMPs will require creative solutions to
providing the necessary funding. It is envisioned that extensive use of LID/GI practices can
reduce the financial burden of replacing and maintaining some of the grey infrastructure.
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Related links
Examples of similar programs and analyses
The City of Overland Park has developed a multiple-objective sports complex based on Lenexa's
model. More information on this project can be found at http://www.olssonassociates.com/our-
projects/overland-park-soccer/index.html.
Key sources
For more information on Lenexa's Rain to Recreation program, see www.raintorecreation.org.
Contact information
Mike Beezhold, Watershed Manager
City of Lenexa Department of Public Works
mbeezhold@ci.lenexa.ks.us
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A.6 Capitol Region Watershed District, Minnesota: Realizing
Cost Savings and Environmental Benefits by Using Green
Stormwater Infrastructure Retrofits
Entity
Name: Capitol Region Watershed District (CRWD)
CRWD is a special-purpose unit of government created to manage and protect the wetlands,
creeks, and lakes in the watershed that eventually drain into the Mississippi River.
Population served: 245,000
Area: 41 square miles
Land use in the area is primarily residential, with tracts of commercial, industrial, and
institutional uses dispersed throughout the watershed. The CRWD includes part of St. Paul,
Minnesota, and the surrounding area (portions of five cities).
Project highlights
> Capital cost savings compared to grey infrastructure. A new storm sewer for conveying
frequent floodwaters to Lake Como was estimated to cost $2.5 million compared to
$2.0 million for implementing GI best management practices (BMPs).
> Multiple benefits achieved. The only benefit of the $2.5 million storm sewer pipe option
would have been to reduce localized flooding in Como Park. The $2.0 million GI BMP
option not only reduced flooding but also reduced the volume of Stormwater runoff,
increased groundwater supplies, improved water quality in an impaired recreational lake
and enhanced the recreational amenities in Como Park.
> High performance documented. The GI BMPs provide high Stormwater volume-reduction
and pollutant-removal efficiencies.
> Cost per pound of pollutant removed established. The total annual cost for implementing
the 18 Stormwater GI BMPs was calculated to be $105,154. By pollutant, the annual costs
per pound were $l,140/lb total phosphorus (TP), $0.32/lb total suspended solids (TSS); and
$0.06/cubic foot Stormwater volume reduction.
> Multi-jurisdiction collaboration achieved. CRWD brought together three cities and a
county to deal cooperatively with drainage coming from their jurisdictions. Highlighting
the benefits of the planned GI BMPs was key to achieving acceptance from all the
stakeholders and developing successful partnerships.
> Model approach adopted. As a result of the project's success, the City of St. Paul now uses
a similar design for under-the-street infiltration trenches for street reconstruction projects.
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Background
Stormwater runoff is the most significant source of water pollution within CRWD. The area
within CRWD is almost completely developed. Forty-two percent of the district is covered by
impervious surfaces. Water quality is impaired and there is localized flooding. In addition, aging
sewer infrastructure has caused drainage problems and sewer overflows. Both the Mississippi
River and Como Lake are listed on the Minnesota Pollution Control Agency's 2008 list of
impaired waters.
The highly developed nature of the district leaves little flexibility for stormwater management.
When the CRWD evaluates BMPs, it is therefore primarily concerned with identifying areas to
retrofit. Through its Arlington Pascal Stormwater Improvement Project (APSIP), CRWD has
worked to reduce stormwater runoff volume and to improve water quality by reducing the
amount of phosphorus, bacteria, mercury, nutrients, polychlorinated biphenyls, and turbidity
discharged into Como Lake and the Mississippi River.
Types of LID/GI solutions
APSIP, substantially completed in 2007, consisted of 18 stormwater BMPs, including eight rain
gardens to address volume control and water quality; eight underground (under-street)
infiltration trenches to address stormwater rate and volume control; a large underground
infiltration/storage facility to reduce flooding and improve water quality; and a regional
stormwater pond, located on the Como Park Golf Course.
In addition to APSIP, CRWD has been involved in the implementation and construction of three
green roof projects, two porous asphalt and concrete systems (parking lots), and numerous rain
gardens within its service area.
Program description
A primary goal of CRWD's stormwater program is to protect, manage, and improve water
resources through the implementation of BMPs that reduce stormwater runoff and remove
pollutants. Monitoring the performance and cost-effectiveness of various BMPs in order to plan
for future implementation is a key component of this goal.
Accordingly, CRWD has focused on implementation, monitoring, and assessment of BMPs as
part of the APSIP. APSIP is a multi-jurisdictional, multi-partner project aimed at improving
water quality in Como Lake. Specific goals of the project include:
> Reduce the frequency and duration of flooding.
> Address needed improvements in storm sewer pipes and roads.
> Reduce the TP and TSS loads to Como Lake.
> Determine an equitable distribution of costs among the jurisdictions.
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Initially, the proposed solution to runoff problems in the Como Lake subwatershed included the
construction of a second 60-inch storm sewer pipe that would convey untreated runoff to Como
Lake at an estimated cost of $2.5 million (not including financing costs). This solution would
reduce much of the localized flooding in Como Park but would not reduce stormwater runoff
volume into Como Lake or improve water quality. The pipe would also result in severe
disruption of the surrounding park area.
On the basis of a hydraulic evaluation conducted in 2003, CRWD and the project partners
designed and constructed 18 stormwater BMPs that have achieved the project goals at a lower
cost, approximately $2.0 million (not including financing costs). The APSIP BMPs include an
underground stormwater storage and infiltration facility (Arlington-Hamline Underground
Stormwater Facility/Arlington-Hamline Facility); a regional stormwater pond (Como Park
Regional Pond); eight underground infiltration trenches; and eight rain gardens.
Construction of the BMPs began in 2005, and the last BMP constructed, the Como Park
Regional Pond, became operational in late December 2007. CRWD monitors the performance of
these BMPs and also conducts regular inspections and maintenance to ensure proper function.
For CRWD, the largest barrier to implementation has been access to land. CRWD does not own
any land, and finding good locations for projects involves partnerships with public landowners
which were mainly municipal governments. In the future, CRWD will look for more
opportunities for partnerships with private landowners. CRWD recognizes that its water quality
goals cannot be achieved without engaging all property owners in some way. The district is in
the process of developing a 10-year management plan that will address this issue. It plans to
focus first on commercial and industrial property owners with large areas of impervious surface.
As an important note, when CRWD began working on flooding and water quality problems in
this subwatershed, there was not a focus on LID/GI solutions. In partnership with the
municipalities within the district, GI BMPs were selected because they most efficiently and
effectively accomplished the project goals. These solutions also provided multiple benefits,
including improved water quality and reduced runoff volume discharged to Como Lake, amenity
values associated with rain gardens and enhancements to the Como Lake Golf Course. These
benefits were important in gaining neighborhood, city, and public acceptance.
APSIP was funded through CRWD's general fund levy, bonds, and partner contributions.
Role of economic analysis
APSIP provided CRWD with a good case study opportunity to evaluate the costs and cost-
effectiveness of different types of BMPs. Upon implementation of the APSIP, CRWD initiated a
comprehensive data collection and monitoring program to assess the effectiveness of the APSIP
project components. The objectives of this program include:
> Determine the volume and pollutant load reductions and volume and pollutant removal
efficiencies (performance) of the BMPs compared to modeled results.
> Determine the costs to construct, operate, and maintain the BMPs.
> Estimate the costs to remove pollutants (cost-effectiveness).
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The resulting report, Stormwater BMP Performance Assessment and Cost-Benefit Analysis
(completed in early 2010), is a comprehensive evaluation that presents actual and modeled
performance results and maintenance data and analysis on select BMPs monitored or maintained
by CRWD in 2007 and 2008. This analysis determined that the BMPs performed as well as, or
better than, anticipated and it has helped guide future project development.
Economic analysis method and results
Method: CRWD's overall method involved calculating the costs and cost-effectiveness of each
BMP. In 2007 and 2008, CRWD collected water quality and quantity data from the APSIP
Stormwater BMPs to determine their effectiveness in reducing stormwater runoff volume and
pollutant loading. Total discharge volume, TP, and TSS loads were calculated for each storm
event at every site using stage, flow, and water quality data. CRWD also assessed BMP
conditions and conducted maintenance to ensure proper performance.
CRWD also estimated the annual costs associated with each of the BMPs, including amortized
capital costs, operation and maintenance (O&M) costs, and periodic replacement. The cost-
effectiveness, in terms of the cost per unit of stormwater volume reduction and pollutant
removal, was then computed for each BMP (on an annual basis).
The annual cost of each BMP was calculated based on three steps. First, annual O&M costs were
analyzed as part of the 2007/2008 monitoring effort. O&M costs were based on total cost of
labor, equipment and materials, and contract services. To estimate these costs, CRWD used
electronic field forms to record the BMP inspected or maintained, the inspection or maintenance
activity occurring, time on and off site, and staff present on site. Projected annual O&M costs
were also determined for each APSIP BMP based on expected labor, equipment and materials,
and contract services costs of an average year using adjusted costs for future years.
Second, the total capital cost of each BMP was calculated by summing the costs of design,
construction, and bond interest. Design and construction costs reflect the amount paid by CRWD
and project partners. The bond interest cost reflects only the amount of the interest cost paid by
CRWD; it does not include any interest paid by project partners. To determine annual capital
costs, the capital costs for each BMP were amortized over the life expectancy of each BMP. A
life expectancy of 35 years, which is an approximate average of individual BMP life
expectancies, was assumed for each BMP.
Finally, CRWD determined total annual project costs by adding the annual capital cost of each
BMP and the annual O&M costs for 2007, 2008, or the projected annual year. Irregular
maintenance costs, such as dredging and bathymetric surveys, were also incorporated into the
annual operating cost amount.
On the basis of this cost information, CRWD determined annual volume reduction and pollutant
removal costs by dividing the total annual cost of each BMP for a given year by the total volume
of runoff infiltrated or by the TP or TSS load removed in that same year, i.e., the cost of
removing a pound of TP and a pound of TSS and the cost for reducing a cubic foot of stormwater
volume. This approach allowed for a side-by-side comparison of BMP removal costs.
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Results: CRWD found that properly designed, constructed, and maintained BMPs are exhibiting
high-volume reduction and pollutant removal efficiencies. Importantly, CRWD found substantial
cost savings associated with the implementation of the APSIP BMPs compared to the use of a
more traditional 60-inch storm sewer pipe solution, i.e., a savings of approximately $0.5 million,
excluding interest.
The APSIP has a total project capital cost of approximately $2.7 million, which includes the cost
of design, construction, and financing costs over the 35-year project period. The project cost
amounted to $2.0 million without financing costs, as reported above. The Como Park Regional
Pond, which incorporates the largest drainage area and storage volume of the BMPs, has the
highest capital cost. This project accounted for half of the total APSIP capital costs. The eight
rain gardens have the lowest capital costs and the smallest drainage area and storage volume.
Exhibit A.6.1 shows the results of CRWD's analysis in terms of total annual project costs,
i.e., amortized capital and O&M costs, and the cost per unit of pollutant removal and stormwater
volume reduction.
Exhibit A.6.1. APSIP BMP annualized costs and cost-effectiveness
Annualized costs
TP
(including annualized removal cost
capital and O&M costs) ($/lb)
Arlington-Hamline facility
Como Park Regional Pond
Infiltration trenches
Rain gardens
Total APSIP costs
$27,473
$43,531
$23,769
$10,381
$105,154
$1,828
$714
$1,909
$2,791
$1,140
TSS
removal cost
$0.54
$0.21
$0.60
$0.39
$0.32
Volume
reduction cost
($/cf)
$0.05
$0.00
$0.03
$0.04
$0.06*
a. The Como Park Regional Pond achieves no volume reduction. The project volume reduction cost is the total annual costs
divided by the total annual volume reduction ($105k/1.7 million cf). This is why the volume reduction cost for the entire project is
greater than that for any of the individual BMPs.
CRWD cautions that the costs reported in Exhibit A.6.1 must be evaluated on a project-by-
project basis and are not directly comparable. For example, although the Como Park Regional
Pond is more cost-effective for TP and TSS removal than some of the smaller, more
decentralized BMPs, this type of solution is generally not feasible in a dense urban watershed.
The pond also was relatively inexpensive because CRWD located the pond on land already in
public ownership. CRWD noted that there are greater opportunities to use rain gardens and
infiltration trenches because they can be integrated into redevelopment and street reconstruction
projects in areas throughout the city while simultaneously providing improved aesthetic value. In
addition, CRWD recognized the benefits of using retention based approaches to reduce
streambank and bed erosion and reduce sediment discharges.
Outcomes: This analysis helped CRWD validate a watershed approach to water resource
management. APSIP has served as a model for how to achieve volume reduction and water
quality standards in dense urban watersheds. For example, the City of St. Paul now uses a similar
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design for under-the-street infiltration trenches in order to comply with rules for street
reconstruction projects.
This project enabled CRWD to bring together three cities and a county to cooperatively deal with
drainage coming from their jurisdictions. The project has also increased awareness of and
support for alternative approaches to stormwater management, from both the public and
CRWD's member cities.
Lessons learned and next steps
CRWD developed the approach for the cost-effectiveness analysis without the benefit of having
many examples to follow. The District looked at a few key questions that would help to move its
program forward. These questions were: What are the costs?; Are these techniques effective?;
and What is the balance between construction and O&M costs?. CRWD wanted to be able to
prioritize projects based on these criteria. One difficulty the district encountered was being able
to account for irregular maintenance costs. For example, Como Park Pond will need to be
dredged and infiltration trenches will need to be cleaned out. However, it is difficult to determine
how frequently these tasks will need to occur. To account for these costs, the District amortized
on an annual basis the O&M costs over the project evaluation period (30 years) to determine an
average O&M cost. In most years, CRWD will spend a lot less than the estimated average annual
maintenance costs.
Although the analysis focuses primarily on BMP performance with regard to volume, TP and
TSS reductions, CRWD sampled and analyzed other chemistry parameters. CRWD plans to
further analyze water quality data collected to determine the effectiveness of the BMPs with
respect to reduction of other pollutants such as metals and bacteria. CRWD is also interested in
researching other entities that have come up with more effective approaches for documenting
effectiveness and costs.
CRWD plans to continue to conduct similar types of analyses every two or three years. In
subsequent studies, the district would like to quantify some of the secondary benefits of some of
the BMPs to assess how they affect the communities' carbon footprint and mitigate urban heat
island effects.
In terms of overall implementation, a key lesson learned is that patience, time, and money are
keys to achieving acceptance from all the stakeholders. At the beginning of the project, there was
significant reluctance, from both citizens and municipalities, to accept this new and different
approach. To address citizen concerns, CRWD hosted public meetings and followed up with
individuals. A significant amount of resources were directed toward gaining acceptance by the
cities involved, agreeing upon an equitable funding allocation, and working with municipal
engineers on effective project design.
The BMPs that have been implemented as part of APSIP have been constructed on public lands
or within the public right-of-way often in in coordination with a major street reconstruction
project. CRWD plans to continue to coordinate projects with redevelopment and street
reconstruction projects. Since it is very expensive for CRWD to implement standalone projects,
CRWD would like to get involved early in redevelopment projects so that stormwater features
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can be integrated into the project at lower cost. CRWD is currently conducting several
subwatershed analyses to identify BMP locations; this will give CRWD an opportunity to
include the BMPs as part of redevelopment projects.
Related links
Examples of similar analyses and programs
Burnsville is another city in Minnesota using GI practices to improve lake water quality. Lacking
space in the right-of-way to implement bioretention practices, Burnsville installed an
experimental rain garden system to infiltrate street runoff. Rain gardens were installed on private
property along streets, and they have reduced runoff by 90 percent. For more information, see
http://www.ci.burnsville.mn.us/index.aspx7NID = 594.
Key sources
For more information on CRWD, see http://www.capitolregionwd.org/.
Contact information
Mark Doneux, Administrator
Capitol Region Watershed District
mark@capitolregionwd.org
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A.7 New York City, New York: Bringing Together Agency
Stakeholders to Assess the Cost-Effectiveness and
Feasibility of Sustainable Stormwater Management in
Combined Sewer Overflow Areas
Entity
Name: New York City (NYC) Mayor's Office of Long-Term Planning and Sustainability,
Sustainable Stormwater Management Plan.
The plan was developed by an interagency task force as a key initiative under PlaNYC, the city's
long-term plan for a greener, greater New York. The task force is composed of 14 city agencies
responsible for infrastructure or development that have a direct impact on pollution in the city's
waterways. Development and implementation of the plan are coordinated through the Mayor's
Office of Long-term Planning and Sustainability.
Population served: 8.4 million
Area: 305 square miles, including all five boroughs
Project highlights
NYC's Sustainable Stormwater Management Plan is a comprehensive analysis of the feasibility
and cost-effectiveness of various LID/GI and traditional grey infrastructure options to control
Stormwater runoff in the ultra-urban NYC setting. Highlights and key findings of the plan
include:
> The implementation of LID/GI-oriented source control strategies is more cost-effective
than the use of traditional grey infrastructure for NYC conditions.
> Based on the analysis conducted as part of the plan, the city has developed and prioritized a
series of promising Stormwater strategies and pilot projects. The pilot projects provide a
framework for further testing, assessment, and implementation of decentralized source
controls.
> The proposed strategies—which include sidewalk standards, road reconstruction standards,
green roadway infrastructure, Stormwater requirements and incentives for low- and
medium-density residences and other existing buildings—present significant opportunities
for controlling Stormwater and reducing CSOs.
> The success of this plan will depend in part on the successful coordination of the many
agencies and stakeholders involved.
Background
Stormwater runoff is one of the greatest water quality challenges in NYC. Inadequately managed
runoff causes flooding in many areas and contributes to CSOs and other untreated discharges that
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result in localized water quality problems. Stormwater runoff is a major reason that many of the
tributaries in the city still do not meet standards for recreational use.
To address these issues, the city has developed a Sustainable Stormwater Management Plan as
part of PlaNYC. PlaNYC's overall water quality goal is to improve public access and
recreational use of the city's tributaries. The city has a goal to increase access from 48 percent
today to 90 percent by 2030. Toward this end, the Sustainable Stormwater Management Plan
evaluates the feasibility of various policies that when fully implemented will create a network of
decentralized source controls to detain or capture over one billion additional gallons of
Stormwater annually. The plan creates a strategy for increasing the use of GI throughout the city
for Stormwater management purposes.
It is important to note that over the last 20 years, the city has drastically improved water quality
in the New York harbor. Many areas meet water quality standards and are available for
recreational use. As outlined in the plan, the city intends to continue these efforts through the
implementation of GI primarily aimed at improving water quality in the tributaries.
Types of LID/GI solutions
The city's plan includes a variety of technological/structural and non-technological/nonstructural
source control measures related to four specific program areas: the public right-of-way, city-
owned property, open space, and private development. Technological source control measures
include green roofs, blue roofs, rainwater harvesting, vegetated controls, tree planting, permeable
pavements, and engineered/constructed wetlands. Non-technological measures include design
guidelines, performance measures, zoning requirements, and economic incentives.
Program description
A key objective of the plan is to evaluate the technical and financial feasibility of source control
strategies in order to plan for future implementation. Accordingly, the plan includes a
preliminary analysis of a variety of GI measures. Based on this analysis, the plan identifies a
number of promising source control strategies and policy initiatives that incorporate different
combinations of these measures. These strategies have been developed at the planning level, and
the details described below do not necessarily represent final implementation alternatives.
Proposed strategies include:
> Performance standards for new development. Standards would require new development to
detain a 10-year design storm with a gradual release rate through proven, cost-effective
technologies such as rooftop detention practices such as blue roof and green roofs.
> Performance standards for existing buildings. Requirements for owners of existing
buildings, with rooftops 10,000 square feet or greater, to meet a one-inch rooftop detention
standard when replacing or making a major modification to the roof.
> Low- and medium-density residential controls. Retrofit of smaller existing buildings in
low- and medium-density residential areas through public education efforts and economic
incentives that encourage adoption of GI practices such as green roofs, cisterns, and rain
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barrels. The city also is considering the adoption of performance standards for smaller
buildings.
> Road reconstruction design standards. Installations of GI practices such as permeable
pavement parking lanes and sidewalk biofiltration cells during scheduled road
reconstruction projects.
> Sidewalk design standards. Installation of permeable pavement for sidewalks in the public
right-of-way and sidewalks adjacent to private property in coordination with planned
replacement schedules.
> Expanding NYC's current Greenstreets program. PlaNYC has already committed to
implementing 80 new Greenstreets every year for the next decade. The plan evaluates the
impacts of expanding this program, by either doubling the number of Greenstreets built
every year or extending the commitment for an additional 12 years. The analyses revealed
that in some watersheds, these additions could make significant contributions to runoff
control, but the overall stormwater benefits would be small.
> Right-of-way build-out. One of the few remaining options is to expand beyond the portions
of the roadway that will be reconstructed over the next 20 years. Any such retrofit program
would be motivated by stormwater retention rather than roadway improvement.
Different types of GI measures included in these strategies will be tested through the
implementation of 20 pilot projects, as identified in the plan. Construction of these projects
began in early 2010. The practices constructed include vegetated swales, enhanced tree beds,
permeable pavements, blue roofs and green roofs. The city intends to monitor the practices for
several years.
In addition to the strategies identified above, the plan also builds upon a number of ongoing
PlaNYC greening initiatives and other city efforts related to stormwater management. Examples
include the planting of a million trees, reforesting 2,000 acres of parkland, zoning amendments
requiring street trees and green parking lots, a green roof tax abatement program, public plazas in
underutilized areas of the roadbed, additional engineered/constructed wetlands in the NYC
Bluebell system, and the conversion of asphalted areas and school playgrounds to turf and trees.
Following PlaNYC's framework of achieving multiple sustainability goals, the plan identifies
opportunities to achieve complementary, non-stormwater benefits such as attractive tree-lined
streets, public plazas, playgrounds, and other planted areas that are intended to transform the
everyday life of city residents and reduce the urban heat island effects.
In terms of program funding, the city has budgeted millions of dollars toward stormwater
management as a result of consent decree negotiations with the State of New York. NYC hopes
to be able to allocate some of this money, which was originally slated for the implementation of
traditional infrastructure, toward GI implementation. To reduce costs of the overall program, the
city plans to implement GI in tandem with public works and other projects already planned for
implementation such as parks, streets and public buildings. The city also is conducting a rate
study to evaluate the benefits of implementing a stormwater fee based on impervious area in lieu
of a flat fee.
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Role of economic analysis
The plan is the city's first comprehensive analysis of the feasibility and cost-effectiveness of
alternative methods for controlling stormwater. The proposed stormwater strategies and pilot
projects were prioritized on the basis of this analysis. The pilot projects provide a framework for
further testing, assessing, and implementing decentralized source controls.
Economic analysis method and results
Method: The plan provides a cost-effectiveness analysis that compares various LID/GI runoff
control options to traditional grey infrastructure options. The city developed life-cycle cost
estimates for a number of different measures, including the present value costs of installation,
operation, and maintenance over the expected lifespan of the practices. The city analyzed both
full and incremental costs. Full costs apply to measures implemented under an accelerated
retrofit program that would install source controls on a schedule that is not coordinated with
other construction. Incremental costs apply to source controls that are installed when roofs,
sidewalks, and/or roads are already being replaced. For example if a roof is being replaced with
the addition of a blue roof, the incremental cost would be the difference in cost between
replacing the roof membrane and the addition of the blue roof elements.
The city was able to estimate total costs for various strategies and policy initiatives, and to
prioritize strategies based on their analysis of the cost-effectiveness of the source control
measures they evaluated. The city compared these costs to those associated with two planned
grey infrastructure projects—the construction of proposed CSO storage tunnels for Newtown
Creek and Flushing Bay.
Results: The city ranked the proposed strategies on the basis of two criteria—feasibility and cost.
As shown in Exhibit A.7.1, these rankings reflect the fact that there is an upper limit to
stormwater runoff reductions, and diminishing returns to cumulative investments in control
options. For the most part, the costs shown below represent incremental costs (with the exception
of some GI measures, such as rain barrels or cisterns that will be implemented independently of
development/redevelopment, capital, or maintenance/replacement programs.
The city presented the costs above under the decision criterion that the most cost-effective
strategies will be implemented first and that they will be fully implemented before additional
options are implemented. The city, however, also recognizes that some of the appropriate
practices can be implemented in parallel rather than sequentially. It also should be noted that the
analysis was based only on stormwater benefits and not other ancillary benefits.
The city, however, recognizes the importance of non-storm water benefits, including improved air
quality, reduced energy demand, carbon sequestration, reduced greenhouse gas emissions,
increased property values and aesthetics, habitat for birds and other wildlife, stream health and
that the development of new local markets can stimulate job growth. At the time of this
interview, the city had not yet been able to quantify or monetize these benefits, and these benefits
have not been folded into the source control policy except as a deciding factor in the cases where
stormwater costs are equal. Based on the results of planned pilot projects and future research, the
city hopes to one day quantify these benefits in monetary terms.
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Exhibit A.7.1. Cost comparison and prioritization of proposed control strategies
Source control strategy
Performance standards for new development
Performance standards for existing buildings
(plus preceding strategy)
Low- and medium-density residential controls
(plus preceding strategies)
Greenstreets (plus preceding strategies)
Sidewalk standards (plus preceding
strategies)
Road reconstruction standards (plus
preceding strategies)
Right-of-way build-outs (plus preceding
strategies)
Grey infrastructure reference case
Potential future CSO detention facilities
Cumulative
runoff
capturea
(million
gallons)
1,174
2,838
3,954
4,178
8,400
9,868
24,092
Total CSO
reduction
2,266
Cumulative
present value
cost
(2010-2030;
millions)
$105
$416
$625
$676
$1,704
$2,123
$19,360
Total
cost
$2,337
Cumulative
cost per
gallon
$0.09
$0.15
$0.16
$0.16
$0.20
$0.22
$0.80
Cost per
gallon for
individual
source
control
$0.09
$0.19
$0.19
$0.23
$0.24
$0.29
$1.21
Cost per
gallon
$1.03
a. Cumulative runoff capture for the source control scenarios refers to gallons of stormwater runoff that can be retained or
detained in those source controls. The city has not yet established the exact relationship between these quantities and the
corresponding reduction in CSOs.
Outcomes: The Sustainable Stormwater Management Plan can be characterized as a "plan to
plan." The plan's analysis and other considerations led the city to adopt short-term strategies to
supplement existing stormwater control efforts, medium-term strategies to develop innovative
and cost-effective source controls, and long-term strategies to secure funding.
In the short term, the city recognizes significant opportunities, and few barriers, in adopting
changes to local regulations to require stormwater performance standards in new developments.
For the medium term, the city identified several source control strategies for implementation.
These strategies—sidewalk standards, road reconstruction standards, green roadway
infrastructure, and stormwater requirements and incentives for low- and medium-density
residences and other existing buildings—present significant opportunities. The city, however,
plans to further vet each of the strategies, based on pilot project results, studies of economic
incentives, resolution of funding and maintenance issues, and settlement on consensus designs.
In the long term, the city will continue to assess stormwater controls at regular intervals to
determine the need for additional measures. Future performance assessments of the effectiveness
and implementation of source controls could affect decisions regarding the construction of
projects slated for implementation. For example, based on such an evaluation, the plans to build
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expensive grey infrastructure such as deep storage tunnels for storm water in Newtown Creek and
Flushing Bay could result in the downsizing or elimination of such projects.
The city also will continue to evaluate long-term funding strategies. There are at least five
potential types of sources for funding stormwater initiatives: (1) rate increases, designated
stormwater rates, or a combination of these fees approved by the independent Water Board;
(2) the general municipal fund; (3) outside funding from other funders including the New York
State Department of State, New York State Environmental Protection Fund, private foundations
and natural resource damage assessment settlements; (4) increased federal funds for
infrastructure improvements; and, (5) funds redirected from conventional infrastructure towards
more cost-effective solutions.
Lessons learned and next steps
The city is pleased with the outcome of the plan in terms of the economic data it provided.
Although the plan indicates that there is tremendous potential for GI in NYC, further testing is
needed. In the future the city would like to examine the costs and benefits of GI at the watershed
level rather than from a city-wide perspective.
A key challenge of the program will be the successful coordination of the various agencies and
stakeholders involved in the plan. For example, a project in the public right-of-way must be
coordinated across several different agencies, including the Department of Transportation, the
Parks Department, the City's Water and Sewer departments, and the Department of Sanitation
(and possibly more). The Mayor's Office is tasked with trying to coordinate communication and
cooperation across agencies from the outset of each project. This level of coordination requires
new relationships and the involvement of agencies whose core mission has not traditionally been
water quality improvement.
In addition, many of the agencies that will be involved in the implementation of GI are
supportive but have concerns related to the O&M costs associated with this type of
infrastructure. Some GI projects do require more maintenance than traditional infrastructure.
Additional staff training or equipment such as vacuum sweepers for porous pavement will be
required. Consequently, agencies will need to secure additional funding to be able to adequately
maintain and operate GI projects.
Related links
Similar programs and analyses
NYC has used LID/GI approaches to address sewer overflow problems on Staten Island since
1991. The Staten Island Bluebell facilities include constructed wetlands, basins, and filters
designed to slow runoff, remove contaminants, minimize erosion and flooding, and promote
groundwater infiltration. For more information on this program, see
http ://www.nyc. gov/html/dep/html/dep_proj ects/bluebelt. shtml.
Indianapolis' planned LID/GI program is focused on encouraging the use of GI in the private
sector and implementing projects on city operations. The city has developed a GI master plan to
help guide implementation of future GI projects. CSO control is the main driver of the program.
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For more information, see
http://www.indygov.org/eGov/City/DPW/SustainIndy/Pages/home.aspx.
Key sources
To download a copy of PlaNYC's Sustainable Stormwater Management Plan:
http://nytelecom.vo.Ilnwd.net/ol5/agencies/planyc2030/pdf/nyc_sustainable_stormwater_manag
ement_plan final .pdf
The 2012 update of the Sustainable Stormwater Management Plan can be found at:
http://nvtelecom.vo.llnwd.net/ol5/agencies/planyc2030/pdf/sustainable Stormwater mgmt_plan
_progress_report_october_2012 .pdf
To view the overall PlaNYC: http://www.nyc.gov/html/planyc2030/html/home/home. shtml.
To access the Department of Environmental Protection (key agency in the development and
implementation of the plan):
http://www.nyc.gov/html/dep/html/home/home. shtml.
Contact information
Aaron Koch
Policy Advisor
New York City Mayor's Office of Long-Term Planning and Sustainability
Akoch@cityhall. nyc.gov
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A.8 Charlotte-Mecklenburg Storm Water Services, North
Carolina: Using Cost-Effectiveness Analyses to Prioritize
Projects that Reduce the Impacts of Rapid Development
Entity
Name: Charlotte-Mecklenburg Storm Water Services (CMSWS)
Charlotte-Mecklenburg Storm Water Services is a stormwater utility that is staffed by both city
and county personnel. About 60 percent of the staff of CMSWS work for the City of Charlotte,
while the other 40 percent work for Mecklenburg County Land Use and Environmental Services
Agency.
Population served: 890,000
Area: 526 square miles
Project highlights
Mecklenburg County has used LID/GI approaches to reduce the impacts of rapid development
on water quality for several years:
> LID/GI approaches were initiated because model results indicated LID/GI was the only
approach that would achieve sufficient pollutant removal and prevent further degradation
of the county's waterways given that traditional stormwater management practices had
failed to prevent sediment buildup in the drinking water reservoir resulting from runoff and
stream erosion.
> The county conducted a cost-effectiveness analysis in a key watershed to determine cost
per pound of sediment saved for various LID/GI program components. Results show that
for this area, stream restoration is the most cost-effective means of controlling sediment.
Stream restoration techniques cost on average between $0.60 to $1.00 per pound of
sediment managed compared to the sediment removal costs that wet ponds and extended
detention wet ponds provided ($35 and $69 per pond removed respectively excluding land
costs).
> Implementation of an LID/GI-based post-construction ordinance in Huntersville (which is a
municipality in the county) to mitigate water quality degradation from future development.
> The county recognizes the importance of using wetlands, vegetated swales and other GI
practices to improve water quality in developed areas.
Background
The primary objective of Mecklenburg County's stormwater program is to protect drinking water
quality and water quality in general. Enhancement of recreational amenities, wildlife habitat and
the protection of endangered species also are goals of the county. Increases in volumes of
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stormwater runoff and associated pollutants due to rapid development have been identified as the
biggest threat to water quality in this region.
There are three priority watersheds in the county: McDowell Creek, Goose Creek, and Gar
Creek. Most of the major creeks in this region are listed as being water quality impaired, due to
sediment, under section 303(d) of the Clean Water Act. Several drivers influence the program
priorities. McDowell Creek empties directly into the Catawba River which is the primary source
of drinking water supply for the area. For this reason, the McDowell Creek watershed is the
primary focus of activity for the county's LID/GI program. The Carolina heel splitter, an
endangered freshwater mussel species, is found in Goose Creek, and there is a total maximum
daily load calculated for Goose Creek.
Types of LID/GI solutions
The county's capital improvement project (CIP) program has three primary LID/GI-based focus
areas: in-stream restoration, upland BMP retrofits, e.g., rain gardens, bioswales, and
reforestation. In addition, the Town of Huntersville has implemented a post-construction LID-
based ordinance intended to mitigate water quality degradation from future development.
Program description
Mecklenburg County's stormwater program is implemented through Charlotte-Mecklenburg
Storm Water Services, a single stormwater utility that serves the City of Charlotte, Mecklenburg
County, and six incorporated towns.
The City of Charlotte and Mecklenburg County have divided stormwater responsibilities
between themselves based on their "major" and "minor" stormwater systems. The county is
responsible for the major system, which includes streams that have watersheds greater than one
square mile in size. The City of Charlotte and the six surrounding towns are responsible for the
minor systems within each jurisdiction. Minor systems are defined as tributaries, channels, pipes,
catch basins, and culverts located on private property or in the street right-of-way and draining
less than one square mile of land.
The county has been implementing LID/GI-based approaches for more than 10 years. The
LID/GI components of the county's stormwater program were initiated based on a watershed
modeling exercise developed for McDowell Creek. The model was used to compare the
effectiveness of alternative stormwater management approaches to that of existing practices at
build-out/full development conditions. This is a practice known as future conditions modeling,
which has helped communities make more sustainable long-term planning decisions. During the
development of the post-construction ordinance, this type of modeling was also used to evaluate
the effectiveness of LID/GI-based BMPs in preventing flooding.
The modeling effort was undertaken because the county recognized that its current approach to
stormwater management, which included traditional stormwater infrastructure, was not working.
McDowell Creek was listed as a 303(d) impaired water body for benthic impairment and the
county's downstream drinking water supply reservoir had elevated levels of nutrients. The
county understood that future development would only intensify these problems. Model results
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indicated LID/GI was the only approach that would achieve sufficient pollutant removal and
prevent further degradation of the county's waterways. Today, LID/GI is implemented in
combination with conventional approaches designed to manage larger storms.
The majority of the county's resources are used to implement stream restoration projects, which
typically involve modification of the stream profile and structure, i.e., a complete reengineering
of the channel to accommodate increases in stormwater from development and prevent habitat
degradation. These types of projects provide the county with the "biggest bang for its buck" in
terms of storm water benefits.
Upland BMP retrofit projects used by CMSWS include rain gardens and vegetated swales. Wet
pond retrofit are also included in the set of practices employed to increase the effectiveness of
the pond in terms of pollutant removal. These projects have been implemented in addition to the
county's Phase 1 and 2 permit requirements.
In the McDowell Creek watershed, two LID/GI projects are under construction, two LID/GI
projects are in the planning phase, and two additional projects are in the very early stages of
evaluation. The projects under construction include a 3 million dollar 3 mile long stream
restoration project and a small-scale BMP retrofit project.
The county prioritizes projects based on the following:
> Cost-effectiveness and feasibility, which includes the landowner acceptance and ability to
obtain an easement.
> Flood reduction benefits.
> Improvements to drinking water quality.
> Improvements to water quality in listed streams.
> Improvements to habitat and endangered/listed species.
Using this prioritization scheme, the county strives to implement need-based projects rather than
opportunity-based projects, i.e., projects where land is available but less cost effective overall.
Obtaining easements from landowners in high-priority project areas has been the most significant
stumbling block to implementation. The county does not use eminent domain to acquire
easements and is not yet in the business of compensating property owners for easements.
Because most of the high-priority projects have significant private property elements, the county
is considering purchasing land in the future.
Charlotte-Mecklenburg Storm Water Services is funded in part through a stormwater fee based
on the area of impervious surface. Revenues from the stormwater fee are dedicated to CIP
funding. To implement LID/GI, the county leverages CIP dollars to obtain additional funds from
various state and local sources, such as the state's 319 grant program, the State Clean Water
Management Trust Fund, North Carolina Ecosystem Enhancement Program, and a local
mitigation bank. The county has also received American Recovery and Reinvestment Act funds
to implement a stream restoration project.
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Role of economic analysis
To prioritize stream restoration and BMP projects in the McDowell Creek watershed, the county
conducted a cost-effectiveness analysis to determine cost per pound of sediment saved for
various LID/GI program components. The analysis provides planning-level estimates intended to
provide direction on implementation decisions to determine which projects will provide the
greatest benefits for the least cost.
The county does not conduct economic analyses of its reforestation projects. Because
reforestation is relatively inexpensive but offers large benefits in terms of air quality and storm
water management, the county has simply committed to making reforestation a priority.
Economic analysis method and results
Method: The county prepared a detailed cost analysis of BMP installation, minor system stream
enhancement/restoration, and major system stream enhancement/restoration in the McDowell
Creek watershed. The results of this analysis were distilled down to a cost per pound of sediment
removed in order to compare stream restoration to BMP installation. The cost estimates
developed reflect capital costs, including costs associated with project design and planning. The
analysis does not include O&M costs or the cost of acquiring land or easements.
For stream restoration, e.g., natural bank stabilization, riparian restoration, and in-stream
projects, the county used comprehensive data on loading rates for McDowell Creek based on a
Rosgen hydrologic assessment to estimate the sediment savings associated with different
projects. Cost estimates are based on a set cost per linear foot of stream restoration which ranged
between $95 and a $200 per linear foot depending on the level of restoration or enhancement
needed. These costs were generated from "rule of thumb" estimates based on previous county
experience with similar types of projects.
The county estimated the cost-effectiveness of proposed retrofit BMPs on the basis of an
evaluation of pilot studies implemented in different land use zones that included commercial,
high-density residential, medium-density residential, and institutional land uses. From these pilot
studies, the county was able to estimate the amount of sediment reduced per acre for similar
types of projects, different types of land cover, and cost per acre. The county used this
information to evaluate the cost-effectiveness of proposed projects expressed as cost per pound
of sediment saved.
Results: The cost-effectiveness of stream restoration and BMP implementation in the McDowell
Creek watershed is presented in Exhibit A.8.1.
Outcomes: Results of the analysis indicate that stream restoration is the most cost-effective
means of controlling sediment in the McDowell Creek watershed. It is more than two times less
expensive to remove a pound of sediment through stream restoration than through the most cost-
effective practices, i.e., vegetated swales.
CMSWS also recognizes that other factors such as habitat loss, increases in water temperature,
and toxic pollutants such as metals and hydrocarbons are also likely causes of macroinvertebrate
population decreases that can be addressed through the use of LID/GI BMPs.
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Exhibit A.8.1. Cost-effectiveness of program components in the McDowell Creek
watershed
LID/GI component $ per Ib of sediment saved
Major system stream restoration/enhancement3 1.02
Minor system stream restoration/enhancement 0.60
Sand filter 24.43
Wet pond 35.15
Wetland 50.33
Rain garden 19.55
Extended detention 69.60
Vegetated swale 3.89
Filter strip 6.23
Pond retrofitb 188
a. It is important to note that for many communities, stream restoration will not always be the most cost-effective solution
because although it reduces the amount of sediment entering the stream, it does not reduce stormwater runoff volume and other
entrained pollutants.
b. A pond retrofit is essentially an upgrade of an existing impoundment to improve its water quality performance or increase flood
control benefits through the retrofit of a riser or a littoral shelf and/or the modification of the berm forming the impoundment.
Lessons learned and next steps
The county would like to obtain better estimates of the O&M costs associated with different
types of projects. This is particularly important because in some jurisdictions, the county is
beginning to take over the maintenance of projects constructed by private entities. For example,
there are many instances where a homeowners association may not fund the necessary operation
and maintenance activities to ensure that the community's stormwater systems are functioning
optimally. By assessing O&M costs for specific LID/GI designs, the county can modify design
standards to minimize these costs.
In terms of the overall program, the county has learned to manage public expectations associated
with different projects by creating a very clear and transparent implementation process. The
county strives to be very clear and up front about individual projects and impacts on the
landowner or public. For example, with any stream restoration project, some tree loss will
typically occur. The county has learned that this can understandably be an issue of concern for
some landowners. The county takes great care at the outset of each project to work with
landowners and the public to explain any tree loss that will occur.
In addition, the county has learned to take the lead in acquiring easements. In some cases, the
county begins the process with the landowner years before a project is scheduled for
implementation. The county is always looking toward the next step.
For the most part, the program enjoys public support. Communities and businesses are starting to
approach the county about implementing projects on their properties. With each project,
however, an educational process must occur. The loss of property, or use of property, is a
recurring issue that must be addressed.
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Finally, the county has shifted its culture to move from implementing opportunity-based projects
to implementing need-based projects. This includes looking at a number of drivers for
implementation and pursuing projects that will provide the largest benefits.
Related links
Examples of similar programs and analyses
The City of Austin, Texas, also prioritizes LID/GI-based projects based on cost per pound of
sediment reduced. For more information on Austin's stormwater program, see
http ://www. austintexas.gov/sites/default/files/filesAVatershed/riparian/SR-12-13 -Riparian-
Restoration-Prioritization-Methodology.pdf
Key sources
For more information on projects implemented or planned for implementation in Mecklenburg
County, see the Charlotte Mecklenburg Storm Water Services project website:
http://charmeck.org/stormwater/Pages/default.aspx
Contact information
Dave Canaan
Charlotte-Mecklenburg Storm Water Services
Dave.Canaan@mecklenburgcountync.gov
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A.9 Portland, Oregon: A Benefit-Cost Analysis Provides the
Basis for Incentivizing Ecoroof Construction
Entity
Name: Portland Bureau of Environmental Services (BES).
The primary mission of Portland, Oregon's BES is to protect the city's clean rivers through water
quality protection, watershed planning, wastewater collection and treatment, sewer installation,
and stormwater management. As part of its stormwater management programs, BES has
implemented the Sustainable Stormwater Management Program, which focuses on green
infrastructure initiatives, including the Ecoroof Program.
Population served: 550,000 (estimated)
Community area: 145.4 square miles
Project highlights
> An analysis of ecoroofs versus conventional roofs in Portland demonstrated sufficient
public benefits to help justify the adoption of an incentive program to encourage private
construction and continue a policy of requiring ecoroofs on city-owned construction
projects. Portland's ecoroof program began in 2001. As of 2008, eight city buildings had
ecoroofs totaling 30,000 square feet, and there were more than 1 million square feet of
ecoroofs and roof gardens within the City of Portland.
> Benefits to building owners were found to be significant, but they do not accrue until
sometime after year 20. By year 40 the city estimated that the owner of a building with an
ecoroof would save a total of $400,000. Given that this longer-term payback may not be
sufficient incentive for developers to build green roofs, the city has provided incentives to
help offset the initial higher costs of ecoroofs. The extended life of ecoroofs as compared to
conventional roofs also helps make the economic case for ecoroof construction.
> A wide array of benefits was identified, and some were quantified and/or monetized. Even
though all of the ecological benefits were not monetized, the analysis shows economic
benefits accrue from ecoroof implementation.
> Other communities can use this analysis to assess the benefits of ecoroofs for improving
the livability of cities and managing stormwater runoff to achieve multiple benefits,
including cost savings.
Background
Portland receives an average of 37 inches of precipitation per year, which creates an annual
volume of stormwater runoff of about 10 billion gallons. This runoff can cause flooding and
erosion, destroy natural habitat, and contribute to CSOs. BES has developed a stormwater
management program that recognizes the need for internal coordination and the promotion of
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sustainable stormwater management systems throughout the entire city. It also helps the city
meet its Municipal Separate Storm Sewer System (MS4) Discharge Permit, address CSO events,
maintain water quality, and control flooding. The Ecoroof program is one of several strategies
that Portland is implementing to address these issues.
Types of low-impact development/green infrastructure solutions
Ecoroofs are one of many city-wide solutions that include green streets, sustainable stormwater
BMP monitoring, school BMPs, and a financing program. Ecoroofs are well suited to Portland's
climate, which includes frequent storm events. BES has provided design standards for ecoroofs
that are appropriate for Portland's climate. The ecoroof design standard includes a moisture mat,
a protection board, a 5-inch growing medium, gravel drainage, a simple irrigation system, and
plants such as sedums, grasses, and wildflowers.
Program description
BES encourages the construction of green roofs because of the multiple benefits green roofs
provide. The city incentivizes green roofs by offering developers floor area bonuses, which allow
additional building space if an ecoroof is installed in proposed buildings within the Central City
Plan District. The Portland City Council also adopted a policy that directs other city departments
to incorporate green building practices in all city-owned facilities and buildings. First adopted in
2001, the City of Portland Green Building Policy was re-passed in 2005 and again in 2009. The
policy specifically requires an ecoroof design and construction on all new city-owned facilities
and all roof replacement projects when technically feasible. Although each department is
responsible for its own buildings, the departments may not use cost as a reason to avoid the
construction of an ecoroof. To deal with department budget concerns, the program provides
funding for stormwater management projects, including ecoroof projects, through various grant
and matching grant programs.
The BES also uses other forms of funding for its ecoroofs and other sustainable stormwater
management practices. For example, federal grants are used for Innovative Wet Weather
Projects. In addition, the BES Watershed Services Division administers Community Watershed
Stewardship Program grants for community-proposed projects and Watershed Investment Funds
and the Office of Sustainable Development offers Green Investment Funds.
Role of economic analysis
In 2008 BES completed a Cost Benefit Evaluation of Ecoroofs, which built upon previous
investigations of the benefits of ecoroofs. This evaluation documents the costs and benefits of
ecoroofs with the goal of using this information to help increase the construction of ecoroofs
throughout the city. The costs and benefits identified in this evaluation show that over a 40 year
useable lifesplan, investment in ecoroof construction generates significant benefits to developers
and building owners. Analysis also shows that the SW and environmental benefits start accruing
immediately upon construction of the practices. BES also has found that documenting the
benefits of green roofs is an important way to encourage development of ecoroofs in the city.
The driving factor in convincing developers and building owners to construct ecoroofs is that
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ecoroofs have twice the lifespan of conventional roofs, i.e., 40 years in comparison 20 years.
Developers also can realize energy savings and stormwater reduction benefits.
Economic analysis method and results
Method: The BES conducted a full benefit-cost analysis that included a TBL analysis of a
hypothetical, new five-story commercial building with a 40,000-square-foot roof in downtown
Portland. BES performed an extensive literature review to identify and quantify the performance,
costs, and benefits of this ecoroof. Where possible, BES used its own stormwater monitoring
data and infrastructure cost data to develop costs and benefits. When quantitative information
was unavailable, the analysis summarized relevant qualitative information.
The analysis examined the increased costs of roof construction and O&M. Benefits quantified in
the analysis include:
> Reduced stormwater quantity.
> Avoided stormwater infrastructure.
> Reduced stormwater system management costs.
> Reduced stormwater fees.
> Reduced infrastructure costs.
> Reduced energy demand.
> Reduced heating, ventilating, and air-conditioning (HVAC) equipment size.
> Reduced energy costs.
> Reduced carbon emissions.
> Improved air quality.
> Enhanced habitat.
> Improved roof durability.
In addition, BES identified, but did not quantify, the following benefits of ecoroofs:
> Increased floor area ratio density bonus potential and expedited permitting.
> Reduced basement flooding.
> Reduced stream restoration/mitigation improvements.
> Reduced stream degradation and improved natural hydrology.
> Improved water quality.
> Reduced urban heat island effects.
> Enhanced carbon sequestration.
> Enhanced aesthetics and greater green space recreational opportunities.
> Increased property values and associated increased tax revenues.
> Reduced building insulation cost and improved acoustical insulation.
> Reduced roof reflectivity and associated urban heat island effect.
> Reduced system development charges and permit fees.
BES plans to further improve its analysis by developing the monetized benefits of increased
habitat, reduced urban heat island effects, and enhanced carbon sequestration.
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Results: BBS calculated the net present value (NPV) of its ecoroof program to the public, i.e., the
public stormwater system and the environment to private property owners, e.g., developers and
building owners, and to a combination of both public and private stakeholders. Based on this
analysis, BBS concluded that the construction of ecoroofs provides both an immediate and a
long-term benefit to the public (Exhibit A.9.1). At year five the net present benefit is $101,660,
and at year 40 the net present benefit is $191,421. For building owners, the benefits of ecoroofs
do not exceed the costs until year 20, when conventional roofs require replacement. In the long
term (over the 40-year life of an ecoroof), the net present benefit of ecoroofs to private
stakeholders is more than $400,000.
Exhibit A.9.1. Summary of ecoroof costs and benefits
Costs
Benefits
Summary
Focus area
One-time Annual One-time Annual
5 year
NPV (2008)
40 year
NPV (2008)
Public costs and benefits
Stormwater management
Reduced system improvements
Climate
Carbon reduction
Carbon sequestration
Improved urban heat island3
Improved air quality
Habitat
Habitat creation
Total public costs and benefits
Stormwater management
Volume reduction
Peak flow reduction3
Energy
Cooling demand reduction
Heating demand reduction
Amenity value
Amenity value3
Building
Ecoroof construction cost
Avoided stormwater facility cost
Increased ecoroof O&M cost
Roof longevity (40-year period)
HVAC equipment sizing
Total private costs and benefits
Total costs and benefits
$60,700 $60,700
-
$29 $145
-
-
$3,025 $15,515
-
$25,300 $25,300
$0 $0 $86,000 $3,053 $101,660
Private costs and benefits
$1,330 $6,822
-
$680 $3,424
$800 $4,028
-
$230,000 ($230,000)
$69,000 $69,000
$600 ($3,077)
$600,000
$21,000 $21,000
$230,000 $600 $690,000 $2,810 ($128,803)
($27,143)
$60,700
-
$845
-
-
$104,576
-
$25,300
$191,421
$45,866
-
$19,983
$23,509
-
($230,000)
$69,000
($20,677)
$474,951
$21,000
$403,632
$595,053
a. The economic literature reports that an ecoroof can provide these economic benefits; however, data that would allow the
calculation of a dollar amount for these benefits for an ecoroof in Portland are unavailable at this time.
Source: City of Portland, Bureau of Environmental Services. 2008. Cost Benefit Evaluation of Ecoroofs.
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Outcomes: As of 2008, eight city buildings had ecoroofs totaling 30,000 square feet. There are
more than 1 million square feet of ecoroofs and roof gardens in the City of Portland, and this
number is growing. Nevertheless, the Cost Benefit Evaluation of Ecoroofs report concluded that
the city might want to evaluate additional ecoroof incentive options for developers to further
encourage ecoroof implementation.
Lessons learned and next steps
BES has been able to quantify many of the ancillary benefits of ecoroofs and has found that
publicizing these benefits presents a more convincing argument for the program than simply
describing the importance of stormwater management. The most effective driver in convincing
the construction industry, developers, and others to construct ecoroofs is the extended life of an
ecoroof—40 years—as compared to the 20-year life of a conventional roof.
Constraints faced by BES include difficulties in extrapolating findings from the literature to the
City of Portland and monetizing benefits. BES hopes to monetize other benefits (e.g., from
carbon sequestration, reduced heat island effects, and increased habitats) in future studies.
Related links
Similar programs and analyses
Seattle, Toronto, and Vancouver have all conducted similar analyses of green roofs. For more
information, visit the links below.
Seattle: http://www.seattle.gov/DPD/GreenBuilding/Resources/TechnicalBriefs/default.asp.
Toronto: http://www.toronto.ca/greenroofs/index.htm.
Vancouver: http://vancouver.ca/olympicvillage/greenbuilding.htm.
Key sources
City of Portland, Bureau of Environmental Services, Sustainable Stormwater Management
Program overview is available: http://www.portlandonline.com/BES/index.cfm7c = 34598.
City of Portland, Bureau of Environmental Services. April 2008. Cost Benefit Evaluation of
Ecoroofs. Available: http://www.port!andonline.com/bes/index.cfm?a=261053&c=50818.
Contact information
For benefit-cost analysis information
Tom Liptan (retired)
Portland Bureau of Environmental Services
toml@bes.ci.port! and.or.us
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For Ecoroof program information
Terry Miller
City of Portland, Oregon
Office of Sustainable Development
tmiller@ci.port! and.or.us
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A.10 Philadelphia, Pennsylvania: A Triple-Bottom-Line Analysis
of Combined Sewer Overflow Control Options
Entity
Name: Philadelphia Water Department (PWD), Office of Watersheds (OOW)
OOW is a unit of PWD's Planning and Engineering Division and is responsible for PWD's
Combined Sewer Overflow (CSO), Stormwater Management, and Source Water Protection
programs.
Population: 1.5 million
Area: PWD's CSO program area covers about 63 square miles within the City of Philadelphia.
The boundaries of the CSO area fall within the watersheds of Tacony-Frankford Creek, Cobbs
Creek, the Lower Schuylkill River, and the tidal portion of the Delaware River Watershed.
Project highlights
> Full and fair comparison of green vs. grey infrastructure for stormwater management. This
comparison was needed to evaluate the best approach for investing the city's funds to solve
the CSO problem in a dense urban environment.
> Triple-bottom-line (TBL) analysis. Financial, social, and environmental considerations
provide insight into the wide array of benefits of GI for urban residents and help guide the
city to obtain the best value for its residents.
> Greater benefits of LID/GI. The TBL analysis demonstrated that, in Philadelphia, for equal
investment amounts and similar overflow volume reductions, supplementing gray
infrastructure with GI provides many times the benefits in economic value, recreational
opportunities, ecosystem enhancement, and reduced construction impacts, compared to a
single-purpose investment in traditional stormwater infrastructure.
> A model for communities to identify and value LID/GI amenity benefits. Realizing the
benefits achieved by GI in urban redevelopment and retrofits can help communities decide
on their own future stormwater management investment approaches.
Background
CSOs are a primary source of pollution to Philadelphia's waterways. During heavy rainfalls or
sudden snowmelts, overflows can occur in various locations throughout the city, at any of the
164 permitted CSOs. Overflows from combined sewers can exceed water quality standards,
threaten aquatic life and habitat, and impair the use and enjoyment of the water body.
Water quality impairment during dry weather, along with limited public awareness and sense of
stewardship, is also a major concern. Common types of impairment include high levels of fecal
coliform, elevated water temperatures, and dissolved oxygen levels below minimum standards.
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Another concern is the presence of litter and unsightly streams, which discourages recreational
use.
In the Tookany/Tacony-Frankford and Cobbs Creek watersheds, degraded aquatic and riparian
habitats and limited diversity offish and other aquatic species pose overlying ecosystem
concerns. In these watersheds, bank and streambed erosion threaten the functions of nearby
utilities, and CSOs impact both water quality and stream channel stability. In the Schuylkill and
Delaware River watersheds, major concerns include the lack of recreational opportunities and
public access to the riverfront and the presence of polychlorinated biphenyls, which has led to
fish advisories.
Types of LID/GI solutions
PWD is committed to the development of a balanced "land-water-infrastructure" approach to
achieve its watershed management and CSO control goals. This method includes traditional
infrastructure-based approaches, as well as a range of land-based stormwater management
techniques and physical reconstruction of aquatic habitats. Together, these approaches form the
basis for PWD's Green City, Clean Waters program.
Land-based stormwater management approaches can be used to restore a more natural balance
between stormwater runoff and infiltration, reduce pollutant loads, and control runoff rates at
levels that minimize streambank erosion. Specific approaches include disconnection of
impervious cover, bioretention, subsurface storage and infiltration, green roofs, swales, green
streets, permeable pavements, and urban tree canopy.
Water-based approaches include bed and bank stabilization and reconstruction, aquatic habitat
creation, plunge pool removal, improvement offish passage, and floodplain reconnection.
Restoring designated uses and ultimately removing streams from the state's list of impaired
waters will require restoration of functions the healthy aquatic ecosystem once provided. These
functions may be impossible to restore without restoration of physical channel and habitat
characteristics required to support them.
Program description
PWD's Green City, Clean Waters program is designed to provide many benefits beyond the
reduction of CSOs. The ultimate goal of PWD's approach is to regain the aquatic and riparian
resources in and around streams that have been lost due to urbanization in and around the City of
Philadelphia, while achieving full regulatory compliance in a cost-effective manner.
With this vision, PWD has reduced capital investments that are typically implemented out of the
public view, i.e., underground or in pipes and instead redirected funds to the implementation of
LID/GI techniques. Central to this strategy is a commitment to city greening, sustainability, open
space, waterfront revitalization, outdoor recreation, and quality of life.
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Based on the land-water-infrastructure approach detailed above, specific implementation
strategies include:
> On public lands, large-scale implementation of green stormwater infrastructure to manage
runoff at the source and reduce demands on sewer infrastructure.
> On private lands, requirements and incentives for green stormwater infrastructure.
> A large-scale street tree program to improve aesthetics and manage stormwater.
> Stream corridor and waterfront improvements to increase access to and improve
recreational opportunities.
> Preservation of open space and the management of stormwater at its source.
> Conversion of vacant and abandoned lands to open space.
> Redevelopment of abandoned lands and brownfields using up-to-date stormwater
management techniques to reduce runoff.
> Restoration of streams using physical habitat enhancements that support healthy aquatic
communities.
> The addition of grey infrastructure when necessary to meet appropriate water quality
standards and flood control needs.
Role of economic analysis
PWD's proposed CSO program will result in multiple social and environmental benefits,
e.g., public health, recreation, housing and property value benefits, that compliment
improvements in water quality. To gain a better understanding of the total benefits, and to
evaluate the use of GI on such a large scale, PWD performed a TBL analysis of various CSO
control options.
PWD believed it was important to analyze the TBL benefits in order to obtain a full and fair
comparison of the use of GI versus traditional infrastructure alternatives. Understanding the full
societal costs and benefits of the program is important in justifying the program to ratepayers,
who will ultimately pay for this initiative.
Economic analysis method and results
Method: Cost-benefit analysis using TBL accounting of benefits and costs expands the
traditional financial reporting framework to take into account the ecological and social
performance of each infrastructure option. Thus, the TBL approach provides for a more complete
and meaningful accounting of PWD activities that reflects all three bottom lines—financial,
social, and environmental.
The TBL assessment provides an evaluation of the "external" costs and benefits associated with
various CSO control options. (That is, benefits that "spill over" into other areas besides water
quality and costs that are not included in traditional engineering estimates of the expense to build
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Appendix: LID/GI Case Studies
and operate facilities.) The suite of CSO control options evaluated includes LID/GI-based
approaches, as well as traditional infrastructure alternatives, e.g., tunneling; transmission, plant
expansion and treatment; and satellite treatment. Each CSO option was evaluated in detail for
each watershed.
Key external benefit and cost categories were identified based on the various components
associated with each option. Most of the external benefits identified only resulted from the
implementation of LID/GI-oriented options and were not realized using traditional infrastructure
alternatives. Key benefit and cost categories in the TBL assessment include:
> Recreation. The LID/GI-based options will result in additional recreational opportunities
due to stream restoration and riparian buffer improvements, as well as a general increase in
vegetated and treed acreage in the city.
> Higher property values. Trees and plants improve urban aesthetics and community
livability. Studies show that property values are higher when trees and other vegetation are
present.
> Heat stress reduction. LID/GI can create shade which can reduce the amount of heat gain
that occurs in urban areas. Vegetation can also emit water vapor which helps to cool air
temperatures. This cooling effect is expected to reduce heat stress-related fatalities in the
city during extreme heat events.
> Water quality and aquatic ecosystem improvements. Watershed restoration efforts under
the LID/GI-based options are expected to generate important improvements to riparian and
water-based resources.
> Wetland creation and enhancement. The watershed restoration efforts are expected to
create or enhance more than 190 acres of wetlands in the relevant watersheds. Additional
and enhanced wetland acres will provide a range of ecosystem services.
> Poverty reduction from local green jobs. GI creates the opportunity to hire local unskilled
(and otherwise unemployed) laborers for landscaping and restoration activities. The
benefits of providing these local green jobs include the avoided costs of social services that
the city would otherwise provide on behalf of the same people if they remained
unemployed.
> Energy savings and carbon footprint reduction. Green space helps lower ambient
temperatures and shade and insulate buildings from wide temperature swings, decreasing
the energy needed for heating and cooling. In addition, diverting stormwater from
wastewater collection, conveyance, and treatment systems reduces the amount of energy
needed to pump and treat the water. Reduced energy demand in buildings, and increased
carbon sequestration by added vegetation, result in a lower carbon footprint.
> Air quality improvements. Trees and vegetation also improve air quality by filtering some
airborne pollutants, e.g., paniculate matter and ozone. Reduced energy consumption also
results in decreased emissions, e.g., sulfur dioxide (SC>2 and nitrogen oxide (NOX) from
power generation facilities. This can reduce the incidence and severity of respiratory
illnesses.
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> Construction- and maintenance-related disruption. All of the CSO options will result in
some level of disruption due to construction and/or program activities. The social costs of
disruption can include traffic delays, limited access to places of business, increased noise
and pollution, and other inconveniences. Construction activities also will likely result in
occasional delays and increased travel times for passenger and commercial vehicle
travelers in Philadelphia.
Based on planned program activities, physical outcomes for each benefit/cost category were
defined and quantified. Physical outcomes include non-monetary measures of benefits and costs,
such as additional recreational visits to a park due to improved riparian areas and stream
restoration, or additional time Philadelphia residents are expected to spend in traffic due to traffic
disruption associated with the program activities.
Monetary values were assigned to the physical outcomes associated with each option based on
standard approaches developed and used by environmental impact and valuation professionals
and organizations. Benefits and costs were evaluated over a 40-year planning horizon (2010-
2049).
To estimate annual benefits for each year of the planning horizon, a time path was applied to
each benefit-cost category to reflect the rate at which benefits and costs are expected to accrue.
The time path was based on planned schedules for implementation, construction, and
maintenance, and a tree growth model that applies to benefits dependent on the number of
additional trees to be planted in the watershed. For example, the benefits associated with air
pollutant removal from trees will not be fully realized in the first year of project implementation
and will continue to accrue as the trees grow. Thus, the analysis takes into account the
percentage of trees planted each year as well as the rate at which the trees grow and mature.
Results: Exhibits A. 10.1 and A. 10.2 provide a summary of findings for two of the CSO control
options under consideration: the 50 percent LID/GI option which assumes that runoff from
50 percent of impervious surface in the City of Philadelphia is managed through GI, and the
30-foot tunnel option which would require the construction of a system of storage tunnels with
an effective diameter of 30 feet that would collect runoff from all of the watersheds in the service
area. These options were chosen to demonstrate the difference in net benefits between green and
traditional infrastructure. The reporting of these results is not intended to indicate that a final
PWD decision will be based on these two alternatives.
The results shown below reflect benefits and external costs accrued over the 40-year study
period. Exhibit A. 10.1 describes the outcomes in terms of the physical outcomes obtained.
Exhibit A. 10.2 provides the estimated monetary value for these outcomes, in present value (PV)
terms (2009 USD). PV estimates are based on an inflation rate of 4 percent and a nominal
discount rate of 4.875 percent, applied over the 40-year planning horizon.
Outcomes: The key finding of this TBL assessment is that LID/GI provides a wide array of
important environmental and social benefits to the community, and that these benefits are not
generally provided by the more traditional alternatives.
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Exhibit A. 10.1. Philadelphia city-wide physical unit benefits of key CSO options:
Cumulative through 2049a
Benefit categories
50% LID/GI option 30-ft tunnel optionb
Additional creekside recreational user days
Additional non-creekside recreational user days
Reduction in number of heat-related fatalities
Annual willingness to pay (WTP) per household for water quality
and aquatic habitat improvements0
Wetlands created or restored (acres)
Green collar jobs (job years)
Change in particulate matter due to increased trees (pg/m3)
Change in seasonal ozone due to increased trees (ppb)
Electricity savings due to cooling effect of trees (kWh)
Natural gas savings due to cooling effect of trees (kBtu)
Fuel used (vehicles for construction and operation and
maintenance; gallons)
S02 emissions (metric tons)
NOX emissions (metric tons)
Carbon dioxide (C02) emissions (metric tons)
Vehicle delay from construction and maintenance (hours of delay)
247,524,281
101,738,547
196
$9.70-$15.54
193
15,266
0.01569
0.04248
369,739,725
599,199,846
493,387
(1,530)"
(38)
(1,091,433)
346,883
$5.63-$8.59
1,132,409
1,452
6,356,083
347,970
796,597
a. The 50% LID/GI and 30-ft tunnel options were chosen as example alternatives to illustrate the differences between green and
traditional infrastructure approaches. This does not imply that PWD has made a final decision regarding the options.
b. 28-ft tunnel option in Delaware River watershed.
c. WTP per household in Philadelphia, Massachusetts, including Bucks, Chester, Delaware, Montgomery, and Philadelphia
counties.
d. Parentheses indicate negative values.
Exhibit A.10.2. City-wide present value benefits of key CSO options: Cumulative through
2049 (2009 million USD)
Benefit categories
Increased recreational opportunities
Improved aesthetics/property value (50%)
Reduction in heat stress mortality
Water quality /aquatic habitat enhancement
Wetland services
Social costs avoided by green collar jobs
Air quality improvements from trees
Energy savings/usage
Reduced (increased) damage from S02 and NOX emissions
Reduced (increased) damage from C02 emissions
Disruption costs from construction and maintenance
Total
50% LID/GI option
$524.5
$574.7
$1,057.6
$336.4
$1.6
$124.9
$131.0
$33.7
$46.3
$21.2
^^^ $(5.6)
$2,846.4
30-ft tunnel option3
$189.0
($2.5)
($45.2)
($5.9)
($13.4)
$122.0
a. 28-ft tunnel option in Delaware River watershed.
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Appendix: LID/GI Case Studies
Based in part on this evaluation, PWD has determined that a Gl-based approach, coupled with
targeted traditional infrastructure, is the approach the city prefers to follow. First, PWD believes
this type of approach will reduce CSO in a cost-effective manner. Second, it meets the broader
goals of PWD's Integrated Watershed Management Approach while maximizing environmental,
social, and economic benefits. Third, PWD believes this approach meets all watershed goals
without causing severe economic hardship for PWD's ratepayers. In addition, public feedback
has expressed a clear and unambiguous preference for an alternative focused on green
storm water infrastructure.
Lessons learned and next steps
Analyses of social and environmental benefits invariably require the use of assumptions and
approaches that interject uncertainty about the accuracy or comprehensiveness of the empirical
results. The methods and principles employed in PWD's TBL analysis, however, are well-
established approaches to quantifying benefits in the field of environmental and natural resource
economics. Throughout their analysis, PWD attempted to be explicit and reasonable about the
assumptions and approaches adopted. For transparency, the research team identified key
omissions, biases, and uncertainties (OBUs) embedded in the analysis, and described how the
results of the analysis would likely have been impacted (e.g., whether benefits would have
increased, decreased, or changed in an uncertain direction) if the omission or data limitation had
been avoidable. In conjunction with the OBU issues, a series of sensitivity analyses were
conducted to explore how changing some of the key assumptions would impact findings.
Related links
Similar programs and analyses
Cincinnati, Ohio, is also integrating LID/GI approaches into its respective long-term control
plans. For more information on Cincinnati's planned program, see
http://www.msdgc.org/downloads/wetweather/greenreport/Files/Green Report.pdf.
Key sources
For a summary of the TBL report: http://www.phillywatersheds.org/ltcpu/Vol02 TBL.pdf
For more information on Philadelphia's proposed CSO control program:
www.phillywatersheds.org.
Contact information
Howard Neukrug, Commissioner
Philadelphia Water Department
howard.neukrug@phila.gov
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A.11 Kirkland, Washington: Ranking Benefits to Help Assess the
Feasibility of LID/GI Approaches in CIP Transportation
Projects
Entity
Name: The City of Kirkland Public Works Department, King County, Washington
Population served: 80,505
Area: 18 square miles
Project highlights
> Decision made to incorporate LID/GI elements during the design phase of all CIP (capital
improvement program) transportation projects.
> Drivers for the LID/GI program included public support, anticipated permit requirements,
and regional experience demonstrated the benefits of LID/GI often outweighed the costs.
> Process established for integration of LID/GI into CIP transportation projects and for
coordination between stormwater engineering and capital projects engineering staff.
Development of a project evaluation matrix to compare and quantitatively rank the benefits of
LID/GI-based transportation projects. The matrix allows the staff to quickly and easily compare
project alternatives using TBL benefit analyses and is especially useful to communities with
limited resources.
Background
In 2007, the Kirkland City Council directed city staff to begin looking for ways to expand the use
of LID/GI in both public and private developments. A number of factors motivated the city to
address LID/GI. A prime driver was political support: The electorate understood the need to take
action to protect Puget Sound and local waterways. The council also wanted to proactively
prepare for anticipated changes to the National Pollutant Discharge Elimination System
Municipal Separate Storm Sewer System permit requirements that were expected to include
LID/GI performance requirements. Requirements for LID/GI were also consistent with the
sustainable urban development/LID/GI initiatives being implemented by Seattle and other
municipalities in the Pacific Northwest. Under this focus, stormwater engineering staff within the
Kirkland Public Works Department began to investigate ways to integrate LID/GI into CIP
transportation projects.
In the past, opportunities to integrate LID/GI into CIP projects were missed because there was
little coordination between the stormwater engineering group and the capital projects engineering
group regarding the potential incorporation of stormwater LID/GI practices into the projects. In
most cases, the stormwater staff would not find out about CIP transportation projects until it was
too late to integrate LID/GI into the project designs. To begin the process of looking for LID/GI
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Appendix: LID/GI Case Studies
elements that could be incorporated into CIP projects, stormwater staff evaluated the feasibility
of integrating LID/GI elements into 10 planned CIP projects. The results of this evaluation are
published in the Low Impact Development (LID) Feasibility Study: Analysis of Opportunities and
Constraints to Incorporate LID Elements into Capital Improvement Program (CIP) Projects in
Kirkland, Washington (Leighton et al. 2007). Stormwater staff in the Public Works Department
conducted the study with the expectation that the capital projects group would design the
projects. The study was a key first step toward integrating LID/GI into CIP projects during the
conceptual design phase.
Types of LID/GI solutions
The implementation of LID/GI in Kirkland's CIP projects has focused primarily on the use of
on-site BMPs as a component of street reconstruction projects. These BMPs are designed to
emulate natural hydrological and ecological processes in order to reduce peak flow and total
runoff volume, improve water quality, and save money by reducing the need for regional
stormwater facilities downstream. Projects were designed to meet required stormwater flow
control criteria, based on the 2009 King County Surface Water Design Manual. These
requirements include matching the 2-year and 10-year peak flow, and matching discharge
durations up to the 50-year peak flow. The manual also requires that a minimum of 10 percent of
the runoff from the impervious area on-site be managed through LID/GI techniques, as feasible.
The objectives for the 10 projects analyzed in the Feasibility Study included the addition and
improvement of sidewalks, bicycle lane additions, pedestrian corridor improvements and
roadway improvements. The LID/GI BMPs used included:
> Bioretention and biofiltration facilities such as swales, rain gardens, stormwater planter
boxes, and tree box filters
> Permeable pavements
> Street lane width reductions.
Program description
Kirkland's LID/GI strategy is to "control the volume of stormwater by integrating site planning
and stormwater management from the beginning of the design process of a project to preserve a
more hydrological functional landscape" (PSAT and WSU, 2005).
In the CIP transportation context, the goal is to integrate LID/GI into the conceptual design phase
of all future projects involving public rights-of-way, when technically feasible. Kirkland uses a
number of LID/GI implementation options which are determined by project site characteristics.
For example, for a project that would have traditionally called for the installation of a new
concrete sidewalk and planter strip, the city might select permeable pavement for the sidewalks,
decrease the lane width, and install a rain garden separating the sidewalk and street. The benefits
of this design change include a reduction in runoff from the permeable sidewalk and reduced
street width, and improved water quality and stormwater flow attenuation from the rain garden.
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Appendix: LID/GI Case Studies
In general, the CIP projects are funded from four main sources—current revenue, reserves,
repaid debts, and external sources. Funding sources for each project vary, and a mix of sources is
often used to meet a projected budget. For some LID/GI projects, additional funding may be
available through grants or other external sources. For example, the City of Kirkland partnered
with King County on a CIP project that incorporated LID/GI elements that were funded by the
U.S. EPA (PSP 2010).
Role of economic analysis
As part of the Low Impact Development (LID) Feasibility Study: Analysis of Opportunities and
Constraints to Incorporate LID Elements into Capital Improvement Program (CIP) Projects in
Kirkland, Washington, Kirkland prepared a detailed evaluation of the 10 CIP transportation
projects planned for implementation. The primary objective of the analysis was to set up a
ranking and selection process for integrating LID/GI into CIP transportation projects. An
evaluation matrix was used to evaluate and rank the potential benefits of the proposed LID/GI
project designs. Nonstormwater related benefits also were included in the matrix to gain a more
complete picture of the benefits that accrue through the use of rights-of-way to achieve multiple
objectives. (Leighton et al. 2007).
The feasibility study is not a traditional economic analysis in the sense that the city does not
provide costs or monetized benefits for the different projects. However, the ranking matrix
provides a way to quantify and rank benefits, taking into account the social, environmental, and
financial aspects of the different projects. This type of analysis offers communities with limited
resources a way to analyze projects taking TBL benefits into account.
Economic analysis method and results
Methods: Exhibit A. 11.1 illustrates the evaluation matrix for two of the 10 projects. As shown in
Exhibit A. 11.1, the matrix provides information on six attributes for each project:
> CIP info. Lists general CIP project information, including project location, funding status,
and whether the project will require a right-of-way acquisition.
> LID/GI approach. Lists the proposed mix of LID/GI elements for the project.
> LID/GI criteria. Includes project-specific cost and effectiveness information for stormwater
function, flow control, or treatment comparing the typical conventional CIP project design
to the LID/GI project alternative. Capital and maintenance costs were compared.
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LEGEND
for Matrix
Score
CIP Location (CIP
Project Number)
ne'^Ave. NE40th
SttoNE60*St
(0001000)
NE 100* St.
(0034000)
High
Moderate
Low
CIP Info
% Funded
83%
100%
CIP w/ ROW
acquisition
No
No
Stormwater Basin
Information
Yarrow Creek
(Preliminary report
for storm* ater
management
requirements being
prepared by Perteet)
tOOth -Moss Bay
116thAveNE-
Forbes Creek
(Stream Protection
Flow Control)
LID
Approach
Proposed LID
Elements
Swales, Porous
Pavement for Multi-
use trail, Reductior
of Current Lane
Widths
lain gardens,
Swales, Porous
Sidewalks,
Reduction of
Impervious
Surface
Low Impact Development (LID) Criteria
LID Stormwater
Function Flow
Control orTieatment
Compared to CIP
(High = 3, Low =1)
High (3)
Reduction of
impeivious surface
versus original CIP
strategy, Improved
water quality treatment.
within Sensitive Areas
Moderate (2)
Reduction of
impervious surfaces
LID demonstration
potential
(High = 3, Low =1)
High (3)
LID adjacent to Sensitive
areas: Yarrow Creek;
Function of LID along a
Multi-modal use corridor;
Visible to other ad|acent
property owners: City of
Bellevue, State Parks,
WSDOT
Moderate (2)
Function of porous
pavements
LID Element Capital
Cost Compared to
Conwntional"
Stormwater
Management (Low Cost
= 3, High Cost =1)
Low Cost (3)
A reduction of new
mpervious surfaces could
reduce or eliminate
detention and/or
treatment structures
Low Cost (3)
Difference in cost of
concrete vs. porous
concrete is not significant.
Eiaseline LID
Maintenance
needs/costs lj_ow Cost
=3, High Cost = 1)
Moderate (2)
Increased in some are as
due to proximity of
Yarrow Creek
Low Cost (3)
Cumulative LID
Valuation Score
High = 12-11
Moderate = 10 8
Low = 7-4
11
10
Exhibit A.11.1. Kirkland benefits matrix for evaluating the feasibility of CIP transportation projects.
Source: Leighton et al. 2007.
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Appendix: LID/GI Case Studies
Other Benefits from Proposed LID Elements
Ecological: stream,
wetland, and/or tree
canopy (High = 3,
Low=1)
High (3)
Deduces pollutants
and peak flows to
Yarrow Creek
Low (1)
This is an opportunity
for a demonstration
project
Habitat and
Human health
(High = 3, Low =1)
High (3)
mprove
downstream
surface water
quality
High (3)
mprove
downstream
surf ace water
quality
Ecological
Connectivity
(High = 3, Low=1)
High (3)
Stream restoration/
irii/asive plant removal,
i mprove access to
Bridle Trails State Park
for equestrians and
other users
Low (1)
Other benefits
(High = 3, Low =1)
High (3)
Traffic calming via
road diet and
delineated
separation for users
Moderate g) LID
feature is visible to
cyclists and
pedestrians
crossing over 405
completing a
bicycle connection
Comprehensive Plan
Framework Goal (EG)
Alignments High = 3
Low =1 (See
Appendix B)
High (3) FG-
1, FG-2, FG-5, FG-7, FG-
9, FG-IO, FG-11, FG-13
High (3) FG
\, FG-2, FG-3, FG-5, FG-
7, FG-9, FG-tO, FG-1 1,
FG-13
Encourages Inter
agency Collaboration
(High = 3, Low =1)
Moderate (2) Project
may engage Kirkland
PI annirig + Public
Works. Possibly
Kirkland + WSDOTor
WA State Parks
Moderate (2) Project
may engage Kirkland
PI anning + Public
Works
Promotes System
wide Carbon neutral
Patterns (High = 3,
Low=1)
Moderate (2) This
project encourages
alternative
transportation, while
using local resources
to manage
stormwater.
Moderate (2) This
project encourages
alternative
transportation, while
using local resources
to manage
stormwater
Cumulative Benefit
Valuation Score
High = 21 -18
Moderate = 17 14
Low = 13-7
19
12
Cumulative
Priority
Valuation
Total LID and
Benefits Valuation
Score High = 33
28 Moderate = 27-21
Low = 20 11
30
22
Collaboration Opportunities
Possibility of pairing
with future
re development of
adjacent site's)
No
No
Possible Public and
Private Maintenance
Partnerships
Bridle Trails State Park,
Local Equestrian
Association, and
WSDOT
Adjacent homeowners
and surrounding
community
Exhibit A.11.1. Kirkland benefits matrix for evaluating the feasibility of CIP transportation projects (cont.).
Source: Leighton et al. 2007.
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Appendix: LID/GI Case Studies
For each criterion used, the city assigned a numeric rating to each project, based on a scale of
high (3), moderate (2), and low (1). These scores were then combined to quantitatively rank the
projects in terms of their cost and effectiveness. As shown in Exhibit A. 11.1, the range for this
cumulative scoring that is shown in the last column of this section is high (12-11), moderate
(10-8), and low (7-4). The high, medium, and low scores were qualitative scores, assigned by
staff based on best judgment and consensus and knowledge of the sites.
> Other benefits Additional LID/GI benefits evaluated in the matrix included ecological
function, habitat and human health, ecological connectivity, and alignment with the
Kirkland Comprehensive Plan Framework Goals. Projects also were evaluated for how
well they encourage interagency collaboration and whether they promote carbon-neutral
behaviors such as increased use of pedestrian and bicycle facilities in comparison to
increasing street widths for vehicular traffic. These benefits were also scored as high (3),
moderate (2), or low (1). The range for the cumulative scoring (shown in the last column of
this section) is high (21-18), moderate (17-14), and low (13-7).
> Cumulative priority valuation. Provides the cumulative score for the LID/GI Criteria and
Other Benefits. The range for the scoring is high (33-28), moderate (27-21), and low
(20-11).
> Collaboration opportunities. Indicates the potential for Kirkland to engage the community,
other agencies, and organizations through the design and maintenance of the proposed
LID/GI elements.
Results: Cumulative priority values for the 10 projects ranged from 22 to 30. Five of the projects
scored 28 or greater, falling in the high benefits category. The other five projects scored between
27 and 21, falling in the moderate benefits category. When projects were evaluated solely on the
LID/GI Criteria, four projects scored in the high benefits category (12-11), three projects scored
in the moderate benefits category (10-8), and three projects were in the low benefits category
(7-4). The projects that scored in the lowest category had one thing in common—high baseline
maintenance costs. In addition, the capital costs for LID/GI stormwater management designs
ranged from low (six projects) to moderate (two projects) to high (two projects) when compared
with costs for conventional stormwater management.
Outcomes: The project evaluation matrix used in the Feasibility Study helped to provide the
institutional framework needed to successfully incorporate LID/GI elements into Kirkland's
transportation CIP projects. Kirkland Public Works Department staff view the study as an
important first step useful in institutionalizing a LID/GI screening and ranking system. Today
nearly all CIP projects, both facilities and transportation related projects, contain LID/GI
elements. In fact, many of the projects evaluated in the feasibility study were constructed with
LID/GI elements.
Today, LID/GI options for CIP projects are investigated as early in the planning phase as
possible. The city's capital projects list is developed on a 6-year cycle and is updated every other
year. Initial information about each project is included when the project is put on the CIP list, but
the specifics are not determined until the year the project comes up for funding. The city project
engineer instructs consultants to consider LID/GI in the early design phase.
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Appendix: LID/GI Case Studies
Lessons learned and what's next
When the first CIP projects with LID/GI components were completed, maintenance and related
funding concerns quickly became an issue. The skill set required for maintaining traditional CIP
projects differs considerably from the skills needed to maintain LID/GI elements. As a result,
resistance from the maintenance staff was a problem. Although this issue has occasionally been
addressed by using maintenance staff from the Parks and Recreation Department, Kirkland views
the long-term solution to be supplemental training for CIP maintenance staff. So far, there has
not been sufficient funding available for this training. Fortunately the city has been able to take
advantage of training provided by the nonprofit organization Save the Sound, although training
opportunities have been limited due to funding issues.
Another maintenance-related issue that arose was the need for LID/GI specific equipment such
as vacuum sweepers to maintain permeable pavements. Without proper maintenance permeable
pavements may clog over time and the benefits of the practice will diminish. Unfortunately, the
City of Kirkland does not own the appropriate vacuum sweeper and it is uncertain whether the
city will be able to properly maintain the permeable pavements. Future decisions regarding the
use of permeable pavements will be influenced by this consideration.
The funding of maintenance is a recurring issue. Even though staff may be trained to maintain
LID/GI practices many LID/GI components have maintenance requirements that require
different practices than do conventional CIP components. For example many bioretention
landscapes are designed to be aesthetically pleasing and public works staff may not be trained
landscapers. Clogging of such systems requires additional skill sets and resources to maintain the
infiltrative capacity of the practices. For CIP projects in residential areas, City of Kirkland has
developed partnerships with homeowners' associations (HOAs) to help provide maintenance for
these systems. For example, private developers installed 10 rain gardens in the public right-of-
way to manage stormwater from a public street installed within the residential plat (Garden
Gate). The HOA provides basic plant maintenance and upkeep to ensure proper function. When
HO As do not exist, the City attempts to get adjacent property owners to perform the plant
maintenance. Although the adjacent property owners are legally required to maintain these areas,
effective rain garden maintenance has been a challenge for Kirkland. Despite these issues,
Kirkland has learned and continues to learn about best practices for implementing LID/GI
techniques. The city supports and advocates for this approach.
Key sources
Krishnan. S., N. Kruse, T. McCorkle, K. Terrell, and J. Clem. 2011. 2011 to 2016 Capital
Improvement Program. City of Kirkland, WA., June 2. Available:
http://www.kirklandwa.gov/Assets/Finance + Admin/2011-2016 + CIP/2011-16 + Final +
CIP.pdf.
Leighton, A., B. Maryman, A. Phillips, and T. von Schrader. 2007. Low Impact Development
(LID) Feasibility Study: Analysis of Opportunities and Constraints to Incorporate LID Elements
into Capital Improvement Program (CIP) Projects in Kirkland, Washington. SvR Design
Company, Seattle, WA. Available: http://www.kirklandwa.gov/Assets/iGlobal + PDFs/Kirkland
+ LID + Feasbilitv + Studv.pdf
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PS AT and WSU (Puget Sound Action Team and Washington State University). 2005. Low
Impact Development: Technical Guidance Manual for Puget Sound. Puget Sound Action Team
and Washington State University Pierce County Extension. May.
PSP (Puget Sound Partnership). 2010. Survey of Local Governments that Participated in the
2005-2009 LID Local Regulation Assistance Project. Puget Sound Partnership. Prepared by
CH2MHill.
Contact information
Gina Hortillosa, Project Engineer
City of Kirkland Public Works
GHortillosa@kirklandwa. gov
Stacey Rush, Project Engineer, LEED AP
City of Kirkland Public Works
SRush@kirklandwa.gov
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A.12 Seattle, Washington: Using an Asset Management Approach
for Optimizing Green Stormwater Infrastructure Application
Entity
Name: Seattle Public Utilities (SPU)
Population served: SPU is a municipal utility that provides water to more than 1.3 million
customers in King County, Washington, and provides essential sewer, drainage, and solid waste
services to about 850,000 City of Seattle residential and business customers.
Area: The city of Seattle is 88.5 square miles, not including water areas.
Project highlights
> SPU reports its Natural Drainage System (NDS) assets, e.g., rain gardens and bioswales in
adherence to the Government Accounting Standards Board Statement 34 (GASB 34) basic
financial statements for state and local government reporting. This enables SPU to show an
increased dollar value of assets from the investment in green stormwater infrastructure
(GSI), which supports SPU's capacity to fund expenditures from the capital budget.
Reporting under GASB 34 also enables SPU to capture the value of these GSI assets, and
make the financial benefits of LID/GI more explicit when planning for future expenditures.
Higher asset value can help result in higher bond ratings, which can enable a utility to
reduce the costs of borrowing funds and help pass lower costs onto customers.
> The use of GSI is required by Seattle's Stormwater Code for all projects "to the maximum
extent feasible." This requirement has led to improvements in the cost-effectiveness of GSI
as design improvements have been made over time.
> SPU manages its GSI projects in coordination with its entire suite of stormwater
infrastructure, balancing the risks between minimizing life-cycle costs and achieving
established service levels across all assets. As part of this asset management process, SPU
conducts business case analyses of all GSI projects.
> SPU is collecting data on the capital costs, O&M costs, and benefits of its GSI projects. It
uses and builds upon this information when analyzing new projects.
> SPU has engaged scientists from the U.S. Fish and Wildlife Service and the National
Oceanic and Atmospheric Administration (NOAA) to conduct monitoring at its Venema
Creek NDS project site to quantify the ability of the project to improve water quality, flow,
and habitat in an urban creek. This information is intended to enable SPU to strategically
select NDS sites and allocate resources in the future.
Background
The primary environmental concerns facing SPU's drainage and sewer system department are
the significant impairment of Seattle's receiving waters and aquatic life from CSOs and
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stormwater runoff. In terms of aquatic life, a key issue is salmon habitat restoration: Two runs of
Puget Sound Chinook salmon that pass through Seattle waters were declared threatened under
the Endangered Species Act in 1999, and SPU has more recently found high Coho pre-spawn
mortality rates in the city's creeks. Flooding of roadways and property from increasing runoff is
also a primary concern (City of Seattle, undated).
The City of Seattle has three different types of storm drainage systems, each of which serves
about one-third of the city's area. Combined sewers serve the downtown area and the inner
neighborhoods that surround the downtown. Separate sanitary sewers and stormwater pipes serve
neighborhoods outside the downtown area that were part of the city prior to 1950. The north end
of the city, which was annexed to the city in 1954, has no formal storm drainage systems. In this
part of the city, stormwater runoff flows to urban creeks, lakes, and the Puget Sound (City of
Seattle, undated).
SPU has developed a comprehensive GSI program to address stormwater management
throughout these areas of the city. The program includes:
> NDSprojects. SPU's NDS projects are aimed at recreating the natural drainage
performance of pre-development pasture conditions within existing city neighborhoods.
NDS limit the negative impacts of CSO and stormwater runoff by redesigning residential
streets to take advantage of plants, trees, and soils to clean runoff and reduce stormwater
flows. SPU tested its NDS program with the Viewlands Cascade pilot project in 2000 and
the Street Edge Alternatives (SEA Street) pilot project in 2001. SPU has now constructed
six NDS projects throughout the city and is in the design phase or preliminary engineering
phase for three other projects (Valentine, 2007; Tracy Tackett, SPU, personal
communication, November 7, 2011).
> GSI for Stormwater Code compliance. The City of Seattle's Stormwater Code requires the
implementation of GSI for all projects "to the maximum extent feasible." This means that
GSI must be incorporated throughout the project site, constrained only by the physical
limitations, practical considerations of engineering design and necessary business practices,
and reasonable financial considerations of costs and benefits (SPU 201 Ib).
> ResidentialRainwiseprogram. SPU's Residential Rainwise program has been developed to
encourage residential customers to take steps to reduce the volume of stormwater sent to
public conveyance systems by implementing measures such as constructing rain gardens,
installing permeable pavements and cisterns, disconnecting downspouts, and improving
soil with compost.
In addition, SPU is revising its Long-Term Control Plan, which will define CSO reduction
projects to be completed between 2016 and 2025 and identify additional projects for which GSI
can be implemented.
SPU's primary revenue source for stormwater management activities is a drainage fee, which
appears on property tax bills. Single-family and duplex properties smaller than 10,000 square
feet pay an annual fee based on parcel size category. The annual fees for larger family and
duplex properties and commercial properties are established per 1,000 square feet based on
categories of the percentage of impervious surface (SPU 201 Ic).
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Since 2002 SPU has used an asset management approach for managing infrastructure and
making resource allocation decisions within each of its four lines of business (wastewater,
drinking water, solid waste, and drainage). SPU defines asset management as "meeting agreed
customer and environmental service levels while minimizing life cycle costs" [SPU undated (a)].
SPU's asset management process allows the utility to make decisions in a transparent manner,
informed by life-cycle and TBL costs and benefits. By integrating GSI projects into the asset
management process, SPU can manage these projects in coordination with its entire suite of
stormwater infrastructure, balancing the risks between minimizing life-cycle costs and achieving
established service levels across all assets.
Types of LID/GI solutions
Seattle's GSI program include a wide range of LID/GI measures, including permeable
pavements, removal of impervious surfaces, rain gardens, planting trees, green roofs, green
alleys, swales, cascades (a series of shallow, rock-bottomed pools that step gradually down the
slope behind a series of dams designed as weirs to temporarily detain flow within each swale),
use of compost-amended soils, and rainwater harvesting.
Program description
This case study illustrates how SPU utilized asset management approaches and integrated them
with the GSI and NDS programs to determine the cost effectiveness of GI approaches in Seattle
neighborhoods that do not have formal stormwater drainage systems. SPU developed its asset
management program based on information obtained from Australian and New Zealand utilities,
which pioneered asset management which are now considered best practices. Exhibit A. 12.1
summarizes the key aspects of SPU's asset management program which have been embedded
into all aspects of the utility's funding decisions for projects. Under this program, SPU requires a
business case study for both capital and O&M projects greater than $250,000. The SPU Asset
Management Committee reviews projects estimated to cost $250,000 to $1,000,000 and
determines whether to approve them. A Corporate Asset Management Committee reviews and
approves projects with costs greater than $1,000,000.
Exhibit A. 12.2 summarizes the key contents of a typical SPU business case study. The type of
economic analysis conducted and specific metrics evaluated as part of the business case study
tend to vary by project. For example, a cost-effectiveness analysis is typically conducted for
projects that are required under state and federal regulations or must occur in order to maintain a
core service of unquestionable value (i.e., projects that "must be done") and projects where all
the options being considered provide the same function and value. A benefit-cost analysis is
conducted for projects that do not meet these two criteria. Benefit-cost analyses typically involve
estimating the net present value of each option under consideration. In general, the analysis
includes an in-depth cost analysis of options, quantification of risks and environmental benefits,
and identification (but usually not quantification or monetization) of social benefits [SPU
undated (b); Terry Martin, SPU, personal communication, May 31, 2011].
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Exhibit A.12.1. Key components of SPU's asset management
program
1. Define service levels
2. Learn about risk
3. Focus on life-cycle costs
4. Use TBL analysis
5. Optimize data and data systems
6. Create plans for each asset category
7. Clarify roles and responsibilities
8. Use Asset Management Committee to make big investment decisions
9. Measure results
10. Participate in industry benchmarking of performance and outcomes
Source: SPU 2011.
Exhibit A.12.2. Contents of a typical
SPU business case study
1. Project information
2. Executive summary
3. Budget and completion
4. Key risks and issues
5. Business case
- Background
- Objective
- Options under consideration
- Economic analysis
- Recommendation
6. Related documentation
It is also important to note that SPU reports NDS measures such as rain gardens, bioswales, and
green roofs but not measures that focus on planting trees or other vegetation in adherence to the
Government Accounting Standards Board basic financial statements requirements for state and
local governments under GASB 34. It assigns value to its GSI assets in the same way as it does
for traditional infrastructure, based on the useful life of the asset and the typical replacement
cycle. The value of its GSI assets includes the cost to construct the measure, to put it into the
ground, and to landscape the area. Because some percentage of plants are expected to die during
the first year, landscaping costs typically include a year of replacement costs for plants. After
that time, any plant replacement costs are considered O&M. For traditional assets, SPU bases its
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estimates on historical costs. Although SPU has good records on CIP projects, there is not a long
history of projects constructed following GSI requirements. Consequently, SPU is working to
capture cost data for its new GSI projects (Kathleen Organ, SPU, personal communication,
November 16,2011).
By reporting its GSI infrastructure under GASB 34, SPU can determine whether assets and
equity value increased over time. If values increase, SPU's can more easily justify funding GI
expenditures using funds from the capital budget. Reporting under GASB 34 also enables SPU to
capture the value of these GI assets in its financial reporting process, and explicitly account for
the financial benefits of GI when planning for future expenditures (Kathleen Organ, SPU,
personal communication, November 16, 2011).
As described above, SPU has conducted several NDS projects. The Venema NDS project
provides a good case study example of how SPU integrated GI solutions into a residential street
under the NFS program. Venema Creek is a tributary of Piper's Creek and represents about 85
acres, or five percent, of the Piper's Creek watershed. There is very limited stormwater
infrastructure in the area and stormwater runoff flows directly into urban creeks and lakes.
The Venema Creek project design incorporates swales on the downslope of each side of the road
right-of-way. Green alleys also can be added where appropriate to compliment runoff reductions
achieved through the implementation of the SPU Residential Rainwise program. The goals of the
project include:
> Improve the hydrologic flow regime by reducing flow volume and reducing peak flow
volume.
> Return the two-year flood frequency event from the current urbanized flow rates and
duration to the predeveloped pasture rates and duration.
> Improve water quality to achieve at least 80 percent removal of TSS from the water quality
storm event.
> Meet specified stormwater conveyance goals for project streets.
> Improve creek habitat.
> Reduce spot drainage problems.
> Provide stormwater conveyance in an area with no formal drainage infrastructure.
Another key goal of this project is to quantify the ability of NDS projects to improve the water
quality, flow, and habitat in an urban creek. The Venema Creek NDS project is the first SPU
project to mitigate the majority of stormwater runoff from a single drainage basin in Seattle. SPU
has engaged scientists from the U.S. Fish and Wildlife Service and NOAA to conduct monitoring
at this site to begin to establish a
quantitative relationship between the end- The Venema Creek NDS project is the first SPU
of-pipe performance of NDS strategies on pmject to mitigate the majority Of stormwater
a basin-wide scale and improvement of the „,., , , . , . . „ ,
,.. rn ,, ,.. . runoff from a single drainage basm m Seattle.
water quality, flow, and habitat. MJ * *
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This information will enable SPU to strategically select sites and allocate resources more cost-
effectively in the future.
As part of its business case for the Venema Creek NDS project, SPU identified the key risks
associated with the project and developed a response plan for each risk. Exhibit A. 12.3
summarizes this analysis. As shown in the table, SPU assigned each risk a probability of
occurrence (high, medium, or low) and estimated its potential impact on project cost, schedule,
scope, and quality.
Exhibit A.12.3. Key concerns and issues associated with Venema Creek NDS project
Risk#
1
Description
Description:
and response plan
Lack of sufficient impervious
Probability
; L
Cost
H
Potential
Schedule
L
impact
Scope
H
Quality
H
surface area mitigated in Venema Creek
basin to measure the creek's hydrological and
biological response.
Response: Monitoring protocols will be useful.
Additional streets could be retrofitted to attain
a measurable response.
Description: There is strong public opposition
to constructing NDS on Palatine Avenue.
Response: Conduct meetings and site visits
with property owners. Continue to secure
neighborhood and political support.
Description: Risk of O&M budget cut leads to
system failure and/or negative community
response to aesthetic implications.
Description: Negative community response if
swales are wet all winter due to extra water
diverted to swales.
Response: Conduct education during design
phase to minimize concerns about Palatine
Avenue, where the most water will be
directed.
Source: SPU 2010c.
Role of economic analysis
The economic analysis was conducted as part of a business case study to evaluate various
options for reducing stormwater runoff and improving habitat and water quality in Venema
Creek. This study is part of SPU's asset management process, which allows SPU to evaluate
projects in a holistic manner, managing costs and risks across the utility's entire suite of assets,
rather than project-by-project.
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Economic analysis methodology and results
Methods: SPU conducted a cost-effectiveness analysis to compare the following options for the
Venema Creek project:
> Base Case: Assumes that the Venema NDS is not implemented, resulting in lost benefits
and opportunities.
> Option 1: Swales will be constructed on 8.5 blocks with one sidewalk per block.
> Option la: Option 1 plus construction of three green alleys with permeable pavement.
> Option Ib: Option 1 plus construction of seven green alleys and implementation of the
Residential Rainwise program.
> Option 2: Swales constructed on 8.5 blocks with one sidewalk per block. This option
differs from Option 1 in the selection of streets included in the project.
> Option 3: Swales on 22 blocks with one sidewalk per block, seven green alleys, and
implementation of the Residential Rainwise program.
SPU also compared the costs of the options described above with the costs of three previously
completed NDS projects—SEA Street, Broadview, and Pinehurst—as well as with the cost of a
"traditional" grey infrastructure system. SPU had developed the traditional cost estimate for an
earlier economic analysis that compared an NDS system with a traditional conveyance system
and infiltration pond, to achieve comparable stormwater benefits.
To compare the proposed options, SPU first calculated the following environmental benefits
associated with improving the Venema Creek habitat:
> Number of "greened acres" (defined as an acre of impervious surface mitigated for
stormwater control).
> Percentage runoff reduction.
> Average annual volume infiltrated (million gallons).
> Two-year peak flow reduction (cubic feet per second, or cfs).
> TSS removed (kilograms/year).
Other benefits described, but not quantified or monetized, included:
> Alleviation of severe local drainage problems.
> Collection of scientific knowledge to help SPU improve the cost-effectiveness of its
strategic approach to restoring Seattle's watersheds.
> Increased property values estimated at up to 5 percent; however, SPU notes that traditional
improvements can also increase property values to some extent.
> Increased neighborhood aesthetics.
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SPU then estimated the total project costs, which include capital costs (e.g., construction costs),
non-construction or soft costs (e.g., design, project management, construction management, and
close-out costs), and O&M costs. SPU estimated low, medium and high estimates of O&M costs
for each option based on its experience with other NDS projects and the assumption that SPU
will provide 100 percent of the maintenance for the Venema Creek project.
Next, SPU calculated life-cycle costs based on the expected life of each asset and then calculated
the present value of life-cycle costs for each option. To compare the proposed options, SPU
estimated the present value of costs for three metrics that correspond to primary project goals:
> Present value of the life-cycle cost per gallon ofstormwater infiltrated, i.e., stormwater
volume reduced.
> Present value of the life-cycle cost per "greened acre".
I Present value of the life-cycle cost per kilogram ofTSS removed (note: TSS is also a proxy
for other pollutants entrained in runoff.
Results: The results of the SPU analysis are shown in Exhibits A. 12.4, A. 12.5, and A. 12.6. The
calculations used for the economic analysis are built, to a certain extent, upon the costs and
benefits that were estimated for prior NDS projects.
Exhibit A. 12.4 summarizes the environmental benefits quantified by SPU for the Venema Creek
options. The differences in environmental benefits that Options 1, la, Ib, and 2 provide are
relatively small. However, the data shows that the environmental benefits from Option 3 are
higher, as is the present value of the costs for this option.
Exhibit A.12.4. Summary of project environmental benefits
Avg. annual 2-yr peak flow
Runoff reduction volume infiltrated
Options
1
1a
1b
2
3
"Greened acres"
28.2
28.4 (est.)
28.7
27.9
30.6
(%)
81%
a
82%
80%
87%
(million gallons)
19.323
19.453 (est.)
19.649
19.095
20.92
reduction
(cfs)
4.4
a
4.7
4.4
7.1
TSS removed
(kg/yr)
2,755
2,801
2,755
2,941
a. Option 1a values are not currently modeled but would be in between Options 1 and 1b. (Note: for all options modeled, the
existing average annual runoff is 23.983 million gallons annually and the existing 2-year peak flow is 10.5 cfs.)
Exhibit A. 12.5 compares the present value of the costs for each option, two previously
completed NDS projects (Broadview and Pinehurst), and the traditional system described above.
The costs of the four Venema options range from $7.3 million to $10.8 million. The costs of the
Broadview and Pinehurst NDS projects were $7.7 million and $7.0 million, respectively and both
were less than the cost of the traditional system which was estimated to be $12.9 million. This
cost estimate is based on an economic analysis that SPU conducted of a previous NDS project.
The traditional grey infrastructure design was the most expensive option using present value
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methods when it was designed to provide equivalent performance in terms of reducing peak flow
and volume, improving water quality, and providing street improvements.
Exhibit A. 12.6 compares the present value of life-cycle costs for the three cost metrics for each
option and for the three previously completed NDS projects. As shown in the table, Option 1 and
Option 2 are the most cost-effective NDS options in terms of the three metrics, and these two
options are also more cost-effective than the three existing NDS projects. These lower costs are
due to design improvements that SPU has implemented since the initial projects, which have
resulted in the ability for each swale in the Venema project to handle more flow than in previous
projects.
PV of Costs
(S Mil. over 100 years at SK)
$14.00
$12.00
$10.00
$8.00
$6.00
$4.00 -
$2.00 -
$0.00
PVofO&M
i PV of CIP (Asssume
2012 const.)
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SPU estimated O&M costs based on three years of experience in maintaining the Pinehurst NDS
project. The utility found that for the first three years of a project, O&M costs, e.g., planting,
mulch, water, weed, trash pickup, soil replacement, are about $3.00 per square foot. From the
fourth year on, i.e., the period after the plants are established, O&M costs range from
$0.75/square foot to $1.20 per square foot. SPU plans to update these costs in the future based on
competitive bidding for the work.
The SPU project team recommended that the utility move forward with Option la. The
environmental benefits from this option are slightly higher than those for Options 1 and 2 (see
Exhibit A. 12.4), but Option la is slightly less cost-effective than these alternatives (see
Exhibit A. 12.6). An advantage of Option la over Option 1 is that it helps minimize the risk of
public opposition to the project by offering improved green alleys as compensation to the
residents who will lose a sidewalk and parking spaces as a result of the project.
Outcomes: As a result of the business case evaluation, SPU proceeded with the design phase for
Option la described above. However, community input obtained during the design process
revealed major concerns related to having only one sidewalk per block because in many cases
this would require actually removing an existing sidewalk. Among other issues, residents would
lose mail delivery if they did not have a sidewalk in front of their houses. Consequently, SPU is
reevaluating both its options and its approach to assessing the options in order to place a higher
value on social costs and benefits.
Lessons learned and what's next
SPU is continually improving its approaches for quantifying life-cycle costs, O&M costs, and
environmental benefits for the various components of its GSI program. The utility expands and
builds on these analyses as it develops business case studies for new GSI projects. (See, for
example, SPU 2010c and SPU undated (c).) As illustrated above, SPU is experiencing difficulty
quantifying and monetizing the social benefits of the program and hopes to expand this analysis
in the future. Nevertheless, SPU is working to find ways to place values on the social benefits of
its GSI projects. For example, SPU is beginning to use methods for quantifying social impacts
compiled by the Center for Neighborhood Technology (CNT, 2010). In addition, SPU recently
developed a "multi-objective decision analysis (MODA)" that is primarily used to choose among
options for CSO projects where benefits are not easily quantifiable. The MODA approach is a
qualitative tool for explicitly assessing and rating the environmental, social, and financial
considerations of alternatives in order to obtain a single value or score for each alternative (SPU
2010a; Emiko Takahashi, SPU, personal communication, November 10 and 18, 2011; Tracy
Tackett, SPU, personal communication, November 7, 2011).
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Key sources and related links
City of Seattle. Undated. Seattle's Natural Drainage Systems: A Low-Impact Development
Approach to Stormwater Management. Available:
http://www.seattle.gOv/util/groups/public/@spu/@ustn/docutnents/webcontent/spu02 019984.pdf.
Accessed 7/7/2011.
CNT (Center for Neighborhood Technology). 2010. The Value of Green Infrastructure: A Guide
to Recognizing Its Economic, Environmental and Social Benefits. Center for Neighborhood
Technology. Available: http://www.cnt.org/repository/gi-values-guide.pdf Accessed 11/7/2011.
GASB (Government Accounting Standards Board). 1999. Summary of Statement No. 34, Basic
Financial Statements—and Management's Discussion and Analysis—for State and Local
Governments. Government Accounting Standards Board. Available:
http://www.gasb.org/cs/ContentServer7c = Pronouncement C&pagename =
GASB%2FPronouncement_C%2FGASBSummaryPage&cid = 1176156699453. Accessed
11/22/2011.
SPU (Seattle Public Utilities). 2010c. Stage Gate-2 for Venema Natural Drainage System.
Presented to AMC on 8/4/2010. Seattle Public Utilities.
SPU (Seattle Public Utilities). 2010a. Multi-Objective Decision Analysis (MODA)for
Assessing the Triple Bottom Line ofCSO Options. September 28. Seattle Public Utilities.
SPU (Seattle Public Utilities). 2010b. Seattle Public Utilities Long-Term Control Plan,
Alternatives Evaluation Report. Volume 2. Conceptual Evaluation. Draft review. December.
SPU (Seattle Public Utilities). 201 la. Asset Management at Seattle Public Utilities (PowerPoint
presentation). Presented by Seattle Public Utilities. January 24, 2011.
SPU (Seattle Public Utilities). Undated (a). Asset Management at Seattle Public Utilities.
Available: https://courses.worldcampus.psu.edu/public/buried_assets/resources/seattle.pdf
Accessed 7/7/2011.
SPU (Seattle Public Utilities). Undated (b). Cost Analysis of Natural vs. Traditional Drainage
Systems Meeting NDS Stormwater Goals. Seattle Public Utilities. Available:
http://www.seattle.gOv/util/groups/public/@spu/@usm/documents/webcontent/spu02 019986.pdf
Accessed 7/7/2011.
Valentine, L. 2007. Managing Urban Stormwater with Green Infrastructure: Case Studies of
Five U.S. Local Governments. Prepared for the Civic Federation for the Center for Neighborhood
Technology. July 30. Available:
http://www.cnt.org/repository/GreenInfrastructureReportCivicFederation%2010-07.pdf.
Accessed 7/7/2011.
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Contact information
Terry Martin, Acting Division Director
Asset Management Group
Seattle Public Utilities
Terry.Martin@seattle.gov
Kathleen Organ, Accounting Manager
Seattle Public Utilities
Kathleen.Organ@seattle.gov
Tracy Tackett, Green Stormwater Infrastructure Program Manager
Seattle Public Utilities
Tracy.Tackett@seattle.gov
Emiko Takahashi, Economist
Seattle Public Utilities
Emiko.Takahashi@seattle.gov
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A.13 Milwaukee, Wisconsin: Optimizing the Potential for
Green Infrastructure to Reduce Overflows and Provide
Multiple Benefits
Entity
Name: Milwaukee Metropolitan Sewerage District (MMSD)
Population served: 1.1 million customers in 28 communities in Greater Milwaukee
Area: MMSD's service area encompasses 411 square miles that span parts of six watersheds.
About 95% of this area is served by sanitary sewers, and combined sewers are used in the
remaining area, which is older and more densely developed.
Project highlights
> The city selected GI to reduce combined sewer overflows (CSO) because of the lower costs
and resulting ancillary benefits, as outlined in the Fresh Coast Green Solutions report.
> An optimization evaluation was performed to investigate the most cost-effective mix of GI
solutions for representative watersheds in Determining the Potential of Green
Infrastructure to Reduce Overflows in Milwaukee.
I The study confirmed the potential of GI to be an important practice that could be used to
improve the environmental, economic, and social conditions in the city.
> The approach developed in the optimization study will help the city plan and implement
future GI projects in a more systematic and cost-effective manner.
Background
As part of its Water Pollution Abatement Program, MMSD invested $3 billion in collection
system improvements to mitigate CSOs over three decades through the mid-1990s. From the late
1990s to 2010, MMSD spent an additional $900 million in grey infrastructure on the Overflow
Reduction Plan that was developed as part of its 2010 Facilities Plan.
In the period preceding 1994, which is when the city's Deep Tunnel and other key grey
infrastructure improvements became operational, the MMSD sewer system experienced 50 to 60
overflows per year. An annual average volume of eight billion to nine billion gallons of overflow
was discharged. Today, that number has been reduced to approximately two overflows per year
which discharge on average one billion gallons of overflow per year. MMSD has proposed an
ultimate goal of eliminating all sewer overflows by the year 2035. In addition, in the separate
sewer service area (SSSA), MMSD is working to improve receiving water quality and reduce the
infiltration of stormwater into the sanitary sewer system in order to minimize treatment costs.
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Appendix: LID/GI Case Studies
To meet stormwater challenges, MMSD will continue to build grey infrastructure. However, as
outlined in the City's Fresh Coast Green Solutions report, the implementation of LID/GI
solutions will be a critical part of the district's plan to reduce and eliminate CSOs, improve water
quality, and reduce the amount of stormwater that enters the separate sewer system when it rains.
MMSD recognizes that in addition to reducing overflows and improving water quality, LID/GI
can offer important environmental and social benefits and help build infrastructure more resilient
to climate change.
Types of LID/GI solutions
To date, MMSD has implemented a number of LID/GI projects and programs, including the
Green Seams Program, which involves purchasing large areas of land along waterways for
preservation and flood control purposes, and a rain barrel program that has resulted in the sale of
more than 50,000 rain barrels. Several additional LID/GI demonstration projects, e.g., rain
gardens, bioretention, green roofs, have been implemented on both private and public lands. To
enhance program effectiveness, MMSD now is focusing on the implementation of a variety of
LID/GI strategies, including porous pavement, block bioretention, regional bioretention, rain
gardens, green roofs, green alleys, and green streets.
Program description
MMSD began implementing LID/GI in somewhat of a "scattershot approach," by promoting the
construction of a variety of projects developed on both public and private lands. MMSD realized
that although these projects were successful in reducing stormwater runoff, the utility needed to
apply a more structured approach to realize significant progress. Accordingly, MMSD developed
the Fresh Coast Green Solutions report, which outlined its GI approach, and developed initial
information on the costs and benefits of various GI strategies.
In developing Fresh Coast Green Solutions, MMSD found that most of the LID/GI strategies
under consideration were relatively less expensive than expanding grey infrastructure storage
capacity in terms of per gallon construction costs. As part of Fresh Coast Green Solutions,
MMSD also identified and provided a qualitative ranking of TBL benefits for various LID/GI
strategies, based on existing literature.
Subsequent to the development of Fresh Coast Green Solutions, MMSD initiated a more detailed
analysis of the potential of LID/GI strategies to help eliminate overflows and provide additional
benefits. This study, Determining the Potential of Green Infrastructure to Reduce Overflows in
Milwaukee, was intended to serve as a programmatic document that will help prioritize the
implementation of LID/GI throughout MMSD's service area. The economic portion of this study
includes a cost-effectiveness analysis and a TBL analysis of various GI practices.
As a result of these planning efforts, LID/GI has been integrated into MMSD's 2020 Facilities
Planning Effort, which is based on a watershed approach. Subsequent analyses and related
reports will help to further integrate LID/GI into the 2035 or 2040 Facilities Plans and other
future planning efforts. As part of its "adaptive management" approach to stormwater
management, MMSD plans to continue to evaluate the effectiveness and benefits of LID/GI
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practices as implementation becomes more widespread and more is learned about LID/GI
implementation.
LID/GI projects installed to date by MMSD have been funded from the same funding mechanism
that provides funds for grey infrastructure, i.e., property taxes levied for capital improvements.
As LID/GI projects are implemented on a large-scale basis, i.e., from the pilot phase to full
implementation, MMSD does not anticipate problems with continuing to use capital funds for
implementation.
Role of economic analysis
MMSD's recently completed draft study, Determining the Potential of Green Infrastructure to
Reduce Overflows in Milwaukee, provides an analysis of the potential of LID/GI to help
eliminate overflows and provide additional financial, environmental, and social benefits. The
study is intended to help optimize the implementation of LID/GI in both the combined and
separate sewer areas of MMSD's service area.
MMSD recognizes that minimizing costs to ratepayers is extremely important. Thus, as a first
step to evaluating the potential of LID/GI, MMSD identified through modeling the most cost-
effective LID/GI solutions, i.e., optimal combinations of specific LID/GI practices, based on
volume reduction potential. This analysis was also used to verify assumptions made in the Fresh
Coast Green Solutions report regarding the comparison of costs for green and grey infrastructure
systems.
MMSD recognizes that moving from a grey to a green and grey infrastructure hybrid system will
require community support and strong partnerships. To build this support, MMSD believes that it
is important to identify and report on the full spectrum of LID/GI benefits. Thus, as a second step
to evaluating the potential of LID/GI, MMSD conducted a TBL analysis to evaluate the range of
economic, environmental, and social benefits associated with various LID/GI practices, and to
determine the degree to which each of the LID/GI practices contributes to the TBL.
Economic analysis method and results
Method: As a first step in Determining the Potential of Green Infrastructure to Reduce
Overflows in Milwaukee, MMSD applied the System for Urban Stormwater Treatment and
Analysis Integration (SUSTAIN) model to a pilot area within the combined sewer service area
(CSSA) to identify the most cost-effective set of LID/GI practices in terms of runoff volume
reduction.
SUSTAIN is a model developed by the EPA to evaluate alternative plans for water quality
management and flow abatement techniques in urban areas. SUSTAIN provides a public-domain
tool capable of evaluating the optimal location, type, and cost of LID/GI practices needed to
meet water quality goals. For more information on SUSTAIN, visit
http ://www. epa. gov/nrmrl/wswrd/wq/model s/sustain/.
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Three sewer sheds were chosen for the pilot SUSTAIN evaluation. These sewersheds were
selected because they were considered to be representative of the entire CSSA in terms of soil
conditions and topography, and because they include a mix of residential, commercial, industrial,
and transportation areas to which a variety of LID/GI practices are applicable.
Next, specific LID/ GI practices, i.e., rain gardens, block bioretention, regional bioretention, bio-
swales, rain barrels, green roofs, porous pavement, and green alleys were evaluated for
applicability within the pilot area based on an analysis of aerial imagery. The potential locations
of each type of LID/GI practice identified from this analysis were digitized in a geographic
information system (GIS) to determine the maximum opportunity boundaries to be evaluated by
SUSTAIN, e.g., maximum roof area available for conversion to green roofs, area of road
available for conversion to porous pavement.
The opportunity boundaries for each type of LID/GI practice were then input into SUSTAIN,
which developed a series of LID/GI solutions, i.e., combinations of GI practices, for different
levels of volume control and cost criteria. Based on this information, MMSD developed a cost-
effectiveness curve for the study area for a representative 10-year period. The cost-effectiveness
curve was used to identify cost-effective solutions at different levels of stormwater volume
reduction.
The maximum volume control achievable through the use of all potential LID/GI practices
within the study area is about 85 percent. However, there is clearly a point above which the
marginal costs of additional controls increase dramatically. To further investigate this threshold,
four solutions at different intervals along the cost-effectiveness curve were selected for detailed
performance evaluation. Key measures for each of the four solutions included percent utilization
of different LID/GI practices, runoff volume control, and reduction in peak flow, total suspended
solids, total nitrogen, and total phosphorus.
Based on this evaluation, Solution 2 from the SUSTAIN model was selected for further
evaluation as part of the TBL analysis. Solution 2, which achieved a 65 percent volume
reduction across the sewer shed, requires the addition of 1.1 acres of porous pavement, 2.7 acres
of green alleys, 2.2 acres of block bioretention, 850 rain gardens, 2.8 acres of regional
bioretention, 1,300 rain barrels, 8.5 acres of roadside porous pavement, and green streets with
2.6 acres of roadside porous pavement and 0.6 acres of rain gardens. These practices drain an
impervious surface area of 225 acres.
For the purposes of the quantitative TBL analysis, the team evaluated 11 TBL indicators, as
identified in Exhibit A. 13.1. Air quality benefits are also qualitatively discussed, as are the
benefits of green roofs.
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Exhibit A.13.1. TBL indicators evaluated
TBL category3
Economic Job creation
Reduced infrastructure costs
Reduced pumping costs
Increased property values
Social Improved quality of life and aesthetics
Increased recreational opportunities
Environmental Reduced stormwater volume
Reduced sediment loading
Increased groundwater recharge
Increased carbon sequestration
Reduced energy use and heat island effect
a. Note that TBL analyses typically have a financial category, rather than an economic category. The economics of a policy or
regulation, e.g., in this case the economics of LID/GI, include all three bottom lines: financial, environmental, and social.
Financial benefits typically represent costs to a utility—for example, avoided grey infrastructure costs. Even though they are
monetized, benefits such as increased property values and job creation are considered social benefits because they provide
benefits to the greater community.
In its Fresh Coast Green Solutions report, MMSD highlighted 10 types of LID/GI practices that,
individually or in combination, could potentially improve stream water quality and reduce
treatment costs for the SSSA and the CSSA. In Determining the Potential of Green
Infrastructure to Reduce Overflows in Milwaukee, these practices were narrowed and simplified
for the purposes of modeling. For the TBL reporting, the team analyzed benefits associated with
six LID/GI practices (all included in Solution 2):
> Rain gardens.
> Bioretention systems including bioretention cells in the public right-of-way, native
landscaping and stormwater trees.
> Bioswales along transportation corridors.
> Rain barrels.
> Porous pavements.
> Green alleys.
MMSD was unable to identify greenway and wetland opportunities in the pilot area which were
two green practices identified in Fresh Coast Green Solutions. So these two practices are
excluded from the detailed quantitative analysis. However, MMSD does provide a general
discussion of their benefits. Green roofs also were omitted from the benefits estimation because
they were not selected for Solution 2.
For the quantitative analysis, MMSD estimated the increase in property values and job creation
associated with LID/GI implementation using benefit transfer techniques. (For example, values
for increased property values and job creation were largely based on findings from A Triple
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Appendix: LID/GI Case Studies
Bottom Line Analysis of Traditional and Green Infrastructure for Controlling CSO Events in
Philadelphia's Watersheds (Stratus Consulting 2009).) To estimate reduced or avoided pumping
and infrastructure costs, MMSD relied on engineering estimates for grey infrastructure
stormwater control costs on a per gallon basis.
The social indicator "improved quality of life" is reflected in the estimated increase in property
values due to LID/GI implementation. Thus, separate monetary values were not developed for
this category. The value of increased recreational opportunities is also partly reflected in the
estimated increase in property values. However, many non-property owners will also benefit
from these opportunities. To provide a quantitative estimate for increased recreational
opportunities, MMSD determined the amount of additional green space that would be available
under Solution 2 as a result of green alleys and bioretention areas. Monetary estimates for the
benefits of increased recreation (aside from those reflected in property values) were not
estimated.
Many of the other environmental indicators, including reduced stormwater runoff, reduced
sediment loading, and increased groundwater recharge, were based on outputs from the
SUSTAIN model. These benefits were quantified based on relevant non-monetary measures,
e.g., acre-feet of reduced runoff, tons of sediment, acre-feet of groundwater recharge. MMSD
also used standard evaluation methods to evaluate reduced carbon footprint and reduced energy
use resulting from the implementation of LID/GI practices.
The TBL indicators have different time horizons for reporting. Several indicators have a one-
time benefit, including increased property values and recreational amenity.l Some environmental
indicators are more appropriate to report in terms of recurring annual benefits: reduced
stormwater runoff, reduced sediment loading, and groundwater recharge. Other indicators have
cumulative benefits that are reported over a 20-year horizon, e.g., carbon sequestration, reduced
energy costs, reduced pumping costs, and reduced social costs due to job creation. Results for the
pilot area are reported below.
In an effort to estimate the TBL benefits for the entire CSSA, the pilot area benefits determined
for Solution 2 were linearly extrapolated based on area. A factor of 25 was used to extrapolate
the results, derived from the ratio of the entire CSSA area to the pilot area. The extrapolation
assumes that land uses, soils, weather, average property values, and the applicability of LID/GI
in the rest of the CSSA are identical to those in the pilot area.
Results: This study confirms that a strategic use of LID/GI, along with traditional grey
infrastructure, can be an effective method of reducing overflows in Milwaukee. Exhibit A. 13.2
presents findings from the pilot area analysis, as well as results for the entire CSSA.
For each benefit evaluated, MMSD shows how each LID/GI practice contributes to the value of
the total benefit. Exhibit A. 13.3 provides a schematic of how each of the GI practices helps to
1 Note that when recreational benefits are monetized, they are typically considered to be annual (rather than
one-time benefits) because the benefits are experienced as long as the increased recreational opportunities are
in place.
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Appendix: LID/GI Case Studies
create jobs under Solution 2, and Exhibit A. 13.4 shows similar information for reducing
pumping costs.
Outcomes: The results of the analysis will be used to help select the projects to implement in the
future, and to show that using LID/GI is a valid and effective approach. MMSD believes that this
report (along with Fresh Coast Green Solutions) will help MMSD employees, regulators, and the
public to understand the multiple benefits of LID/GI and move it forward. In addition, the
Natural Resources Defense Council (NRDC) approached MMSD about working together to
build upon their LID/GI planning efforts identified in Determining the Potential of Green
Infrastructure to Reduce Overflows in Milwaukee. Together, NRDC and MMSD have developed
a LID/GI benefits calculator that includes economic and baseline data developed as part of the
Determining the Potential of Green Infrastructure to Reduce Overflows in Milwaukee study. For
more information visit http://www.h2ocapture.com/.
Exhibit A.13.2. Benefits of Gl in Milwaukee CSSA in monetary and non-monetary terms
TBL indicator
Pilot area
CSSA
Improved aesthetics and quality
of life
Job creation
Reduced infrastructure costs
Reduced pumping costs
Increased recreational
opportunities
Reduced stormwater volume
Reduced sediment loading
Increased groundwater recharge
Increased carbon sequestration
Reduced energy use and heat
island effect
$2.7 million property value increase $68 million property value increase
$220,000 reduction in social costs per
year, with a present value of $2.7
million over 20 years
Not reported
$46,000 present value savings over
20 years
11-acre increase in recreation area
through green alleys and bioretention
areas
435 acre-feet of reduced runoff per
year
68 U.S. tons per year
406 acre-feet per year
Reduction of 156 tons of carbon
dioxide (C02) over 20 years
64,000 kWh reduction in energy use
and $3,900 to $5,700 in energy
savings over 20 years (due to
increased shading)
$5.5 million reduction in social costs
per year, with a present value of
$68 million over 20 years
66 to 77% reduction in per unit
storage costs
$1.2 million present value savings
over 20 years
275-acre increase in recreation area
through green alleys and bioretention
areas
10,875 acre-feet of reduced runoff per
year
1,700 U.S. tons per year
10,150 acre-feet per year
Reduction of 3,900 tons of C02 over
20 years
1.8 million kWh reduction in energy
use and $98,000 to $143,000 in
energy savings over 20 years (due to
increased shading)
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Appendix: LID/GI Case Studies
$3,000,000
c
o
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$2,500,000
j= £ j- $2,000,000
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BJ *^ rtt
30 S £
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•° S ™
nj .5
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f V
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• Green Alleys
U Porous Pavement
U Bio-swale
HBioretention
• Rain Gardens
y Rain Barrel
PilotArea
Exhibit A.13.3. Estimated present worth social cost reduction due to job creation over
20 years.
43
i
•§.—
E g
f 1
6 o
^" r~»
1
U
3
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$50,000
$45,000
$40,000
$35,000
$30,000
$25,000
$20,000
$15,000
$10,000
$5,000
$0
• Green Alleys
U Porous Pavement
y Bio-swale
y Bioretention
y Rain Gardens
• Rain Barrel
PilotArea
Exhibit A.13.4. Estimated present worth tunnel pumping cost reduction over 20 years.
Lessons learned and what's next
Although the SUSTAIN pilot application was performed on an area within the CSS A, MMSD
stresses that GI can have a similar if not greater impact in the SSSA. Each of the practices
simulated in SUSTAIN can also be used in the SSSA, and some practices might be even more
effective. For example, the pilot SUSTAIN application assumed a residential rain gardens size of
50 square feet in size due to the small yards in the area. To the extent that there are larger yards
in the SSSA, which includes more suburban areas that the pilot study, rain gardens could also be
designed to be larger. The water quality benefits of LID/GI also will be much more significant in
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Appendix: LID/GI Case Studies
the SSSA because each pound of pollutant treated is a pound that would otherwise be discharged
into the nearest waterway. MMSD's paper, Why Green Infrastructure and I/I Go Hand in Hand,
provides additional information on the GI issues related to separate sanitary sewers.
When MMSD began implementing LID/GI in 2002, there was not a lot of support within the
water and wastewater community or within the district's own utility. Although regulators such as
the EPA, the mayor of Milwaukee, and the State of Wisconsin had been supportive of piloting
LID/GI, they were not fully on board with the LID/GI approach which was proposed as a
substitution for part of the grey infrastructure investment for CSO control.
Gaining internal support was an initial critical concern. However, support has increased over
time because of successful demonstration projects, education, and the hiring of staff who support
the LID/GI approach. Overall, MMSD recognizes that although reducing overflows and
improving water quality is its primary concern, TBL benefits are important and are essential to
building public support.
MMSD has learned that valuable public outreach benefits are associated with LID/GI
demonstration projects. For example, implementation of a rain garden demonstration project in a
public building influenced local residents to install rain gardens in their own yards.
Neighborhood associations and schools have also been effective in educating the public.
This process has also educated MMSD in regards to implementing LID/GI on private lands. In
many instances private property owners have not maintained their projects. Because of its
experiences with BMP maintenance on private property, MMSD now recognizes the need for a
formal maintenance agreement with the property owner and regarding how the practice works
and how it should be maintained. When implementing projects on private lands, MMSD now
enters into an agreement with the property owner that lays out the cost share and post-
construction maintenance plan. MMSD has no liability for these projects.
Finally, MMSD has developed a strong GIS program to coordinate its LID/GI efforts. The use of
GIS mapping techniques allows MMSD to track all of its projects by LID/GI type and location.
In the long term, MMSD's goal is to use GIS to develop a more formal asset management
program.
Related links
For more information on MMSD's LID/GI program, see:
> Fresh Coast Green Solutions:
http://v3.mmsd.com/AssetsClient/Documents/sustainability/SustainBookletwebl209.pdf
> Why Green Infrastructure and I/I/ Go Hand in Hand:
http://www.waterbucket.ca/wcp/sites/wbcwcp/documents/media/139.pdf.
For more information on the LID/GI calculator developed by MMSD and NRDC, see
http ://www.h2ocapture. com/.
For more information on the SUSTAIN model, visit
http ://www. epa. gov/nrmrl/wswrd/wq/model s/sustain/
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Contact information
Karen Sands
Manager of Sustainability
Milwaukee Metropolitan Sewerage District
260 West Seeboth Street
Milwaukee, WI 53204
ksands@mmsd.com
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