&EPA
United States
Environmental Protection
Agency
EPA230R16001
May 2016
www.epa.gov/smartgrowth
CITY GREEN: INNOVATIVE GREEN INFRASTRUCTURE
SOLUTIONS FOR DOWNTOWNS AND INFILL LOCATIONS
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ACKNOWLEDGMENTS
This report was prepared with the assistance of Horsley-Witten Group.
EPA Project Leads: Lisa Hair, Office of Water, and Melissa Kramer, Office of Sustainable Communities
If you have questions about this publication, please contact:
Melissa Kramer
Office of Sustainable Communities
U.S. Environmental Protection Agency
1200 Pennsylvania Avenue NW (MC 1807T)
Washington, DC 20460
Tel 202-564-8497
Kramer.melissa@epa.gov
Reviewers:
Lynn Desautels, Chitra Kumar, and Megan Susman - EPA Office of Sustainable Communities
Katelyn Amraen, Leah Germer (ORISE Fellow), and Jamie Piziali - EPA Office of Water
Trish Garrigan and Rosemary Monahan - EPA Region 1
Rabi Kieber and Maureen Krudner - EPA Region 2
Anne Keller and Christine McKay - EPA Region 4
Robert Newport - EPA Region 5
Suzanna Perea - EPA Region 6
David Doyle - EPA Region 7
Stacey Eriksen - EPA Region 8
Carolyn Mulvihill and Luisa Valiela - EPA Region 9
Jeremy Chadwick, Alan Fody, and Jessica Noon - Philadelphia Water Department
George Grinton - City of Aiken, South Carolina, Engineering and Utilities Department
David Misky - Redevelopment Authority of the City of Milwaukee
Mercy Davison - Town of Normal, Illinois
Mark Doneux and Anna Eleria - Capitol Region Watershed District (Minnesota)
David Pike - City of Santa Fe Public Works Department
Ken MacKenzie - Urban Drainage and Flood Control District (Denver, Colorado)
Tracy Tackett - Seattle Public Utilities
Cover photo credits (top to bottom, left to right): Joe Mabel via Wikipedia Commons, Wenk Associates,
La Citta Vita via flickr.com, Hoerr Schaudt Landscape Architects/Scott Shigley.
Regional context map credits (on the first page of each case study): National Geographic, Esri,
DeLorme, HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, increment P Corp.
Content may not reflect National Geographies current map policy.
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TABLE OF CONTENTS
Executive Summary i
I. Introduction 1
II. Waltham Watch Factory 8
III. Queens Botanical Garden 14
IV. Kensington Creative and Performing Arts High School 19
V. The Radian Complex 25
VI. Sand River Headwaters Green Infrastructure Project 30
VII. Menomonee Valley Industrial Center 34
VIII. Uptown Normal Circle 40
IX. The Metro Green Line 45
X. Santa Fe Railyard Park and Plaza 50
XI. Stapleton Greenway Park 55
XII. Mint Plaza 60
XI11 .Thornton Creek Water Quality Channel 66
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EXECUTIVE SUMMARY
Communities of all sizes and in all climates are
using green infrastructure to manage stormwater
where it falls using the natural processes
associated with soils and vegetation to capture,
slow down, and filter runoff, often allowing it to
recharge ground water. Green infrastructure
manages stormwater to control flooding from
small storms and improve water quality and
offers a wide range of other environmental,
economic, public health, and social benefits.
This publication is for local governments, private
developers, and other stakeholders who help
shape redevelopment projects in downtowns and
infill locations where development has already
occurred. It provides inspiration and helps
identify successful strategies and lessons learned
for overcoming common barriers to using green
infrastructure in these contexts. The examples
could encourage cities to adopt policies that
would expand the number of projects
incorporating similar green infrastructure
approaches.
Twelve case studies showcase projects from
around the country that have overcome many
common challenges to green infrastructure at
sites surrounded by existing development and
infrastructure. In these cases, space is at a
premium, and soil conditions are often unknown
or unsuitable for infiltration. The case studies
help identify successful strategies and lessons
learned for overcoming common problems. The
case studies are:
• The Waltham Watch Factory, Waltham,
Massachusetts.
• Queens Botanical Garden, Flushing, New
York.
• The Kensington Creative and Performing Arts
High School, Philadelphia, Pennsylvania.
• The Radian Complex, Philadelphia,
Pennsylvania.
The Sand River Headwaters Green
Infrastructure Project, Aiken, South Carolina.
The Menomonee Valley Industrial Center,
Milwaukee, Wisconsin.
The Uptown Normal Circle, Normal, Illinois.
The Metro Green Line, St. Paul, Minnesota.
Stapleton Greenway Park, Denver, Colorado.
Santa Fe Railyard Park and Plaza, Santa Fe,
New Mexico.
Mint Plaza, San Francisco, California.
Thornton Creek Water Quality Channel,
Seattle, Washington.
Though green infrastructure can be more
challenging to implement in redevelopment
projects compared to projects in undeveloped
areas, the barriers are usually surmountable.
These case studies help counter real and
perceived obstacles to using green infrastructure
in downtowns and infill locations by providing
successful examples showing that:
• Careful site planning and selection of
practices allow green infrastructure to work
on contaminated sites and sites with poor
soils.
• Historic properties can incorporate context-
sensitive green infrastructure compatible
with the historic fabric.
• Green infrastructure fits into highly space-
constrained sites.
• Municipalities are removing regulatory
obstacles to allow green infrastructure
projects.
• Green infrastructure can provide effective
stormwater management in arid climates and
areas where water rights are a concern.
• Green infrastructure can be a cost-effective
approach to stormwater management and
can help drive economic development.
• Long-term maintenance can be addressed by
thoughtful upfront planning and innovative
approaches.
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I. INTRODUCTION
Communities of all sizes and in all climates are
using green infrastructure to manage
stormwater where it falls. Techniques such as
permeable pavement, bioswales, rain gardens,
and green roofs use the natural processes
associated with soils and vegetation to capture,
slow down, and filter runoff, often allowing it
to recharge ground water.1 Other techniques
like rain barrels and cisterns collect and store
water for future use.2 Green infrastructure
manages stormwater to control flooding from
small storms and improve water quality. It also
offers a wide range of other environmental,
economic, public health, and social benefits
(Exhibit 1). As developers and local
governments recognize the multiple benefits of
site-scale green infrastructure, they are
increasingly incorporating it into
redevelopment projects in downtowns and infill
locations.
This publication is for local governments,
private developers, and other stakeholders who
help shape redevelopment projects in
downtowns and infill locations. Twelve case
studies showcase projects from around the
country that have overcome many common
challenges to green infrastructure at sites
surrounded by existing development and
infrastructure. In these cases, space is at a
premium, and soil conditions are often
unknown or unsuitable for infiltration. The case
studies help identify successful strategies and
lessons learned for overcoming common
problems. In addition, by documenting the
multiple benefits of green infrastructure,
particularly in the redevelopment context,
these case studies provide inspiration for local
governments and private developers who want
to use green infrastructure strategies. The case
studies could encourage cities to adopt policies
that would expand the number of projects
Exhibit 1. Potential benefits of green
infrastructure
Green infrastructure can make the most of
limited funds by producing multiple benefits
with a single investment. These benefits
include:
Improved water quality.
Reduced municipal water use.
Ground water recharge.
Flood risk mitigation for small storms.
Increased resilience to climate change
impacts such as heavier rainfalls and
hotter temperatures.
Reduced ground-level ozone.
Reduced particulate pollution.
Reduced air temperatures in developed
areas.
Reduced energy use and associated
greenhouse gas emissions.
Increased or improved wildlife habitat.
Improved public health from reduced air
pollution and increased physical activity.
Increased recreation space.
Improved community aesthetics.
Cost savings.
Green jobs.
Increased property values.
For more information about achieving multiple
benefits from green infrastructure, see: EPA.
Enhancing Sustainable Communities with Green
Infrastructure. 2014. https://www.epa.gov/smart
growth/enhancing-sustainable-communities-green-
infrastructure.
1 For a complete description of different green
infrastructure approaches, see: EPA. "What is Green
Infrastructure?" https://www.epa.gov/green-infrestructure
/what-green-infrastructure. Accessed Apr. 12, 2016.
incorporating similar green infrastructure
approaches. The case studies are:
• The Waltham Watch Factory, Waltham,
Massachusetts.
2 Green infrastructure also encompasses larger-scale
management strategies, including preserving or restoring
flood plains, open space, wetlands, and forests. However,
this document focuses on site-scale practices.
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attle, Washington
n Francisco, California
St. Paul, Minnesota
Milwaukee, Wisconsin
<• Waltham, Massachusetts
* (
Denver, Colorado ?°rma'' "lin°is ,' ^"""H- New York
Philadelphia. Pennsylvania
Santa Fe, New Mexico
Aiken, South Carolina
Exhibit 2. Locations of profiled projects.
Queens Botanical Garden, Flushing, New
York.
The Kensington Creative and Performing
Arts High School, Philadelphia,
Pennsylvania.
The Radian Complex, Philadelphia,
Pennsylvania.
The Sand River Headwaters Green
Infrastructure Project, Aiken, South
Carolina.
The Menomonee Valley Industrial Center,
Milwaukee, Wisconsin.
The Uptown Normal Circle, Normal, Illinois.
The Metro Green Line, St. Paul, Minnesota.
Stapleton Greenway Park, Denver,
Colorado.
Santa Fe Railyard Park and Plaza, Santa Fe,
New Mexico.
Mint Plaza, San Francisco, California.
Thornton Creek Water Quality Channel,
Seattle, Washington.
Although green infrastructure can be more
challenging to implement in redevelopment
projects compared to projects in undeveloped
areas, the barriers are usually surmountable.
These case studies help counter real and
perceived obstacles to using green
infrastructure in downtowns and infill locations
by providing successful examples showing that:
• Careful site planning and selection of
practices allow green infrastructure to
work on contaminated sites and sites with
poor soils.
• Historic properties can incorporate
context-sensitive green infrastructure
compatible with the historic fabric.
• Green infrastructure works in highly space
constrained sites and can even be a better
choice than conventional stormwater
management approaches.
• Municipalities are removing regulatory
obstacles to allow green infrastructure
projects.
• Green infrastructure can provide effective
stormwater management in arid climates
and areas where water rights are a
concern.
• Green infrastructure can be a cost-
effective approach to stormwater
management and can help drive economic
development.
• Long-term maintenance can be addressed
by thoughtful upfront planning and
innovative approaches.
-------
A. CAREFUL SITE PLANNING AND SELECTION OF PRACTICES
ALLOW GREEN INFRASTRUCTURE TO WORK ON
CONTAMINATED SITES AND SITES WITH POOR SOILS
In many infill locations, developers suspect that
soils might be unsuitable for infiltration or that
past industrial and commercial activity has
polluted the soil and water. However, with early,
careful planning to reduce the potential of
contaminating ground water with suspected
pollutants, green infrastructure can help these
sites become attractive assets to the community.
Often testing reveals either no or only partial
contamination of a site, and site planners can lay
out the development to ensure that green
infrastructure practices will not mobilize
contaminants. Designers can also select practices
that function without infiltrating stormwater into
the soil, including green roofs and cisterns. In
addition, they can cover contaminated soil with
an impervious barrier topped with clean soil and
vegetation that filter and evapotranspire
stormwater before it reaches an underdrain
(located above the barrier) that is connected to
the stormwater system.
Construction of the Kensington Creative and
Performing Arts High School in Philadelphia
occurred on a site contaminated by former
industrial uses. Designers incorporated green
infrastructure by avoiding areas where
contaminants might be mobilized, maximizing
infiltration in suitable areas, and using
techniques that posed no contamination risk,
such as underground storage for stormwater and
a green roof. Together, these approaches
allowed the site to reduce runoff and pollution
entering the combined sewer system.
Developers of Mint Plaza in downtown San
Francisco learned that the infiltrative capacity of
the native soils was much greater than
anticipated. The site was designed to manage a
5-year storm event on-site, but actual
performance has approached the 25-year storm
event,3 showing that even older, dense
downtown locations can be good candidates for
green infrastructure and that soil testing early in
the design phase can help developers plan green
infrastructure that works with the existing
conditions.
Designers of the Waltham Watch Factory
redevelopment project also faced a site
contaminated by past uses. To deal with this
challenge, they lined the rain gardens in the
interior courtyards with an impermeable
geomembrane. The gardens filter runoff from
the surrounding roofs and courtyard paving
without posing any threat of mobilizing
contaminants in the underlying soil.
B. HISTORIC PROPERTIES CAN INCORPORATE CONTEXT-
SENSITIVE GREEN INFRASTRUCTURE COMPATIBLE WITH
THE HISTORIC FABRIC
In many historic neighborhoods, on-site
management of stormwater was once more
common than it is today. Semi-permeable
gravel or brick pavers, cisterns, open streams,
and gardens were a part of the historic fabric.
Context-appropriate incorporation of green
infrastructure can thus be compatible with
historic properties and can even enhance an
area's historic character. In the process of
helping to restore degraded waterways, green
infrastructure can also enhance the historic
character of buildings and neighborhoods,
3 A "25-year storm event" is a storm having a 25-year
recurrence interval based on historical data. In other words,
a storm of that magnitude has a 4 percent chance of
happening in any given year.
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creating spaces that honor an area's heritage
and that residents and visitors cherish.
A mid-19th century watch factory in Waltham,
Massachusetts, was redeveloped as a mixed-use
development with apartments, offices, and
restaurants. It incorporates green
infrastructure that reduces polluted runoff,
improves wildlife habitat, and connects
residents, workers, and visitors to the Charles
River, a water body central to the city's
heritage.
In Santa Fe, New Mexico, preserving the
historic features at an abandoned railyard and
incorporating public open space helped garner
community support for redevelopment. A 10-
acre park that manages stormwater provides a
lively community space next to a new arts and
entertainment district that includes a reopened
historic train depot, a performing arts center,
art galleries, restaurants, and shopping.
In Aiken, South Carolina, residents were
concerned about alterations to the town's
historic parkways. However, once they
understood how planned green infrastructure
practices would look and function and that they
would help protect the nearby Sand River,
residents supported the installation.
C. GREEN INFRASTRUCTURE FITS INTO HIGHLY SPACE-
CONSTRAINED SITES
Downtown properties and infill sites are often
space limited. To make projects in these areas
financially viable, developers have to maximize
the developable area. Green infrastructure
practices such as green roofs, permeable
pavement, underground cisterns, and structural
tree planters can work where space is
constrained. In some cases, creating shared
green infrastructure facilities can allow
individual properties to meet stormwater
management requirements.
The Radian Complex is a 500-bed student housing
and retail center on the northwest edge of the
University of Pennsylvania campus in
Philadelphia. Before redevelopment, the site was
99 percent impervious and close to other
buildings and infrastructure, which limited
infiltration opportunities. A green roof, pervious
pavers, tree pits and planters, and two
underground stormwater detention basins let the
project meet stormwater management
requirements to reduce runoff volumes by
20 percent while maximizing the area available
for retail development.
The Northgate district redevelopment project in
Seattle, Washington, incorporates end-of-pipe
water quality treatment for a highly impervious
680-acre sub-watershed. The 2.7-acre
stormwater facility has become a haven for
wildlife and much-needed open space for
residents of new senior and multifamily housing,
retail customers, and people using the
connection between the neighborhood and
transit station.
The Stapleton Airport redevelopment is one of
the largest infill projects in the country, located
just 6 miles from downtown Denver. The
developer integrated green infrastructure into
parks and open space, creating centralized
facilities that meet water quality, flood control,
and open space requirements. These areas are
now a selling point for the development and a
beloved part of the community.
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D. MUNICIPALITIES ARE REMOVING REGULATORY OBSTACLES
TO ALLOW GREEN INFRASTRUCTURE PROJECTS
In many downtown and infill locations, long-
standing regulations can sometimes present
barriers to incorporating green infrastructure
that discourage developers from pursuing this
approach. As more local governments recognize
green infrastructure's benefits, they are helping
to break down these barriers. Often, a single
successful and popular project is enough to
change government policy and allow future
projects.
The city of St. Paul and the Capitol Region
Watershed District incorporated green
infrastructure into a new light rail line linking
the cities of St. Paul and Minneapolis. They also
installed green infrastructure on adjacent streets
along the corridor, and the entire area serves as
a demonstration project for other developments
in the city.
When designers planned Mint Plaza in San
Francisco, the city's codes prohibited directing
runoff from adjacent roofs to the plaza's
infiltration chambers. When the city issued new
stormwater design guidelines a few years later,
it changed that policy to encourage developers
to use green infrastructure such as infiltration
chambers to manage runoff on-site, ensuring
that future projects will not face this limitation.
The Queens Botanical Garden in New York City
was a pilot project for the city Department of
Design and Construction's High Performance
Buildings Program, which had the goal of making
new and renovated public buildings in the city
environmentally sustainable. By demonstrating
the feasibility of incorporating environmentally
sustainable features into new public buildings,
the city was able to institute new requirements
for future city projects.
E. GREEN INFRASTRUCTURE CAN PROVIDE EFFECTIVE
STORMWATER AAANAGEMENT IN ARID CLIAAATES AND
WHERE WATER RIGHTS ARE A CONCERN
Green infrastructure can manage stormwater and
conserve water resources in arid regions if
designers select plants for their drought
tolerance and use other landscaping techniques
that reduce the need for irrigation. Even in areas
where water rights laws preclude certain
practices, green infrastructure can still be an
effective approach to stormwater management.
The Santa Fe Railyard Park in New Mexico
incorporates shady riparian areas, a dry gulch
that fills seasonally with rain, ornamental
gardens adapted for dry conditions, and historic
Pueblo gardens into a 10-acre park filled with
native and drought-resistant plants. An
innovative water-harvesting system compatible
with water rights restrictions irrigates the
landscape.
The Stapleton Airport redevelopment in Denver
uses vegetated swales and constructed wetlands,
which satisfy requirements not to retain, reuse,
or store runoff. These techniques allow green
infrastructure for water quality treatment even
in an area where water rights restrictions limit
the practices that can be used.
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F. GREEN INFRASTRUCTURE CAN BE A COST-EFFECTIVE
APPROACH TO STORMWATER AAANAGEMENT AND CAN
HELP DRIVE ECONOMIC DEVELOPMENT
Project developers are often concerned about
costs for green infrastructure, particularly for
downtown and infill sites where the range of
appropriate practices can be narrower than on
sites developed less compactly. However, green
infrastructure can be a cost-effective way to
meet stormwater requirements in downtowns
and infill sites, particularly as new materials are
developed and contractors gain experience. In
addition, green infrastructure can create
projects that appeal to residents and business
owners, helping to fill homes and attract
businesses. These economic benefits can help
municipal governments and private developers
justify green infrastructure's cost.
In Normal, Illinois, a $15.5 million
redevelopment project to create a new
community space in a traffic circle that
incorporates innovative stormwater management
has led to $160 million in private business
investment in the Uptown District. In addition,
property values went up 16 percent, and retail
sales grew 46 percent. Public education about
the multiple environmental, economic, and
social benefits helped generate community
support for the initial infrastructure investment.
Redevelopment of a former industrial brownfield
site into the Menomonee Valley Industrial Center
incorporated a centralized green infrastructure
stormwater management system that provides
the community a new recreational park with
access to the Menomonee River. Property values
at the site increased 1,400 percent between
2002 and 2009, adding more than $1 million a
year to city property tax revenues. The 10 firms
at the site had 1,400 employees as of 2015 on
what was once an abandoned site.
Developers of San Francisco's Mint Plaza
recognized that the plaza would create an
outstanding amenity that would pay dividends by
making the company's surrounding properties
more valuable and desirable. Since the plaza
opened, new restaurants, hotels, and cafes have
opened nearby, demonstrating the plaza's
economic value.
G. LONG-TERM AAAINTENANCE CAN BE ADDRESSED BY
THOUGHTFUL, UPFRONT PLANNING AND INNOVATIVE
APPROACHES
Communities are often concerned about the
long-term maintenance of green infrastructure
because it requires practices, resources, and
expertise different from those already in place
for conventional stormwater infrastructure.
Indeed, proper maintenance of green
infrastructure is critical to its long-term success.
Maintenance will be needed to retain the
planned water quality benefits and maintain
community support, which can diminish if green
infrastructure starts to look unkept. Planning in
advance for maintenance requirements helps
local governments and developers ensure that
the benefits of green infrastructure will continue
for years to come.
The Menomonee Valley Industrial Center
redevelopment in Milwaukee, Wisconsin,
incorporates a stormwater park, creating a
public amenity that has generated community
support for the project and contributed to its
overall success. Volunteers planted trees and
collected trash during and after construction,
which helped generate a sense of community
ownership in the project. Volunteers from local
schools, businesses, and neighborhood
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associations continue to regularly plant new
trees and shrubs, remove invasive species, and
pick up trash.
Normal, Illinois, has a stormwater utility fee that
generates dedicated revenue for green
infrastructure projects. These funds implement
more green infrastructure in the community and
ensure long-term maintenance of those projects.
Developers of Mint Plaza in San Francisco formed
an independent, nonprofit organization to
manage maintenance and programming on the
plaza, including a farmers market and arts
performances. The organization also hosts
private, revenue-generating events at the site to
pay expenses. Identifying funds for long-term
maintenance at the time of project planning was
an important part of the public permitting
process because it eased the city's concern
about who would be responsible for these costs.
H. CONCLUSION
These 12 case studies illustrate a range of
circumstances in downtown and infill locations
where green infrastructure practices perform
well. As local governments and developers look
for ways to efficiently use development funds,
these examples help illustrate that green
infrastructure can effectively control stormwater
while helping to achieve other environmental,
economic, public health, and social goals.
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Lexington .W"-
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268 square miles, encompassing all or parts of 32
communities4 and is part of the most densely
populated watershed in New England.5
Excessive algae and aquatic plants significantly
impair water quality in the Upper/Middle Charles
River. Massachusetts was required to develop a
Total Maximum Daily Load (TMDL), which sets
the maximum amount of a single pollutant that
can enter a waterway while still allowing it to
meet water quality standards. The TMDL
determined that phosphorus loads must be
reduced by 50 percent through a 66 percent
reduction from wastewater treatment plants and
a 51 percent reduction from stormwater runoff.6
Before redevelopment, 80 percent of the 12-acre
mill complex was covered with impervious
surfaces, including buildings and pavement. Its
stormwater drainage system was more than 100
years old, consisting of an ad hoc assemblage of
catch basins and pipes that discharged untreated
stormwater directly to the Charles River. Many of
the pipes were routed under existing buildings
and were broken or plugged.7 In addition, the
site offered no public access to the river.8
Contamination due to its past industrial uses
Exhibit 3. The Waltham Watch Factory sits on the bank of
the Charles River. Its redevelopment gives people access
to the river.
created challenges for using green
infrastructure, but the antiquated drainage
system and the project's proximity to the
Charles River made it important to reduce
phosphorus loads and improve water quality.
B. PLANNING AND REGULATORY CONTEXT
The project required a special permit under the
city's Riverfront Overlay District.9 The city
established the district to guide the
redevelopment of land along the Charles River.
The overlay district is meant to promote
development compatible with a riverfront setting
and increase public holdings, public views of,
and public access to the river. However, the
overlay district does not address stormwater
issues or the use of green infrastructure.
Although the city did not require green
infrastructure at the project site, Watch City
Ventures recognized that the river was a
signature asset for its waterfront property, and
water quality improvement in the river
necessitated reducing stormwater flows to the
river. Therefore, Watch City Ventures made a
4 Charles River Watershed Association and Numeric
Environmental Services, Inc. Total Maximum Daily Load for
Nutrients in the Upper/Middle Charles River, Massachusetts.
2011. http://www.mass.gov/eea/docs/dep/water/resources
/n-thru-y/ucharles.pdf.
5 Charles River Watershed Association. "Charles River
Watershed." http://www.crwa.org/charles-river-watershed.
Accessed Apr. 29, 2015.
6 Charles River Watershed Association and Numeric
Environmental Services, Inc. op. at.
7 Reed, Peter, and Kate Bowditch. The Watch Factory: A Case
Study in Low Impact Development and Community
Involvement. 21st Annual Nonpoint Source Pollution
Conference. May 17-19, 2010. https://www.neiwpcc.org/
npsconference/10-presentations/Reed%20and%20Bowditch
%20-%20Watch%20Factory. pdf.
8 Charles River Watershed Association. "Waltham Watch
Factory." http://www.crwa.org/blue-cities/demonstration-
prolects/waltham-watch-factory. Accessed Apr. 29, 2015.
9 City of Waltham. "Zoning Code. Sec. 8.4 Riverfront Overlay
District special permit (RF)." Amended Dec. 9, 1991.
http: / /ecode360. com /269 38380.
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commitment early in the design process to
include green infrastructure practices and
invited the Charles River Watershed Association
to join the development team as an independent
consultant to evaluate plans, propose
alternatives, and provide feedback on the
project.10 City officials liked the green
infrastructure plans that Watch City Ventures
presented during the permitting process so much
that the zoning board made implementing those
plans a condition for approving the project.
C. DESIGN AND PERFORMANCE
The project's stormwater discharge into the
Charles River required adherence to the
Massachusetts Stormwater Management
Standards11 and a permit from the local
conservation commission. The standards require
redevelopment projects to meet or exceed 10
performance standards to the maximum extent
practicable and, more importantly, to
demonstrate improvement over existing
conditions.
The site design, per recommendations from the
Charles River Watershed Association, also
focused on reducing the temperature and
nutrient levels of stormwater runoff (Exhibit 4).
Overall, the site was designed to:
• Treat the first inch of stormwater runoff
from any impervious surfaces to reduce
phosphorus levels and improve water quality.
• Recharge groundwater with up to 0.6 inches
of runoff from impervious surfaces to the
maximum extent practicable, conforming to
the Massachusetts Department of
CHARLES RIVER
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Exhibit 4. The Waltham Watch Factory site plan shows how landscaped spaces were integrated throughout the project to
reduce overall impervious area.
10 Charles River Watershed Association, "Waltham Watch
Factory" op. cit.
11 Commonwealth of Massachusetts. Massachusetts
Stormwater Handbook. 2008. http://www.mass.gov/eea/
agencies/massdep/water/regulations/massachusetts-
stormwater-handbook, htm I.
10
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Exhibit 5. Dennison Courtyard before and after redevelopment shows how new canopy trees, rain gardens, and tables make the
space functional and inviting.
Environmental Protection groundwater
recharge criteria.
• Minimize the speed and volume of
stormwater runoff from the discharge point
along the river.
Phase 1 met these design objectives through a
reduction of total site impervious area. At the
exterior parking lots along Crescent Avenue,
stormwater passes over a grass filter strip that
drains into deep infiltration trenches to provide
pretreatment and ground water recharge,
reducing runoff to the municipal stormwater
drainage system. Along the exterior perimeter of
the existing mill buildings, the old pavement was
replaced with grass filter strips and infiltration
trenches that capture roof and surface runoff.
Finally, rain gardens in the interior courtyards
filter runoff from the surrounding roofs and
courtyard paving (Exhibit 5). The rain gardens
are lined with an impermeable geomembrane
because soil contamination in this area precludes
infiltration.
Overflow structures for all three locations
convey runoff from larger storm events into a
closed pipe system that discharges into the
Charles River. The site is designed to reduce
peak runoff volume between 5 and 9 percent,
depending on the size of the storm.12 Phase 2
involved using porous asphalt to reduce flow,
volume, water temperature, and nutrient loading
at the Prospect Street parking lot.
High groundwater and soil contamination limited
the use of green infrastructure in the parking
area along the river. Instead, designers used
more conventional drainage structures with oil-
water separators and hydrodynamic separators
that remove sediment and other pollutants.
After three years, visual site inspections during
both dry and wet periods indicated all of the
green infrastructure practices were meeting or
exceeding expected infiltration rates. In
addition, freezing and sanding of the parking lots
during the winter do not appear to have affected
performance.13 Testing conducted during a storm
in 2013 found that discharge from the two
courtyard rain gardens had 30 to 50 percent less
nitrate, 30 to 40 percent less phosphate, and
60 percent more dissolved oxygen than
stormwater on-site that did not flow through the
rain gardens.14 The Prospect Street parking lot
courtyard, with its preserved mature shade
trees, was 13°F cooler in the summer than the
Robbins courtyard, which does not have mature
trees.15
12 Landscape Architecture Foundation. "Watch Factory,
Phases 1 and 2." http://landscapeperformance.org/case-
study-briefs/watch-factory. Accessed Apr. 30, 2015.
13 Personal communication with Kate Bowditch, Charles River
Watershed Association, and Eric Ekman, Berkeley
Investments, Inc., on Apr. 5, 2011.
14 Landscape Architecture Foundation op. cit.
15 Ibid.
11
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D. COSTS AND FUNDING
The total construction budget for phase 1 of the
project was $25 million.16 Federal and state
historic tax credits, state brownfield
redevelopment tax credits, and a historic tax
credit bridge loan supplemented private
funding.17 Stormwater management for phase 1
was $434,600, or 2 percent of total project costs
(Exhibit 6). Green infrastructure is often
incorporated into other site design features,
making it difficult to isolate its capital costs
from the overall construction budget. For
example, the rain gardens were larger (and more
expensive) than necessary to manage stormwater
because designers wanted to make them
attractive amenities.
STORMWATER MANAGEMENT PRACTICE QUANTITY UNIT COST COST
Brown Street lot infiltration trench
Brown Street lot tree well with tree
Building 4 front courtyard infiltration trench
Pedestrian Courtyard rain garden
Dennison Courtyard rain garden (including all landscape elements)
Total
220
2
135
270
700
$161 per linear foot
$6,050 each
$142 per linear foot
$622 per square foot
$286 per square foot
$35,400
$12,100
$19,200
$167,900
$200,000
$434,600
Exhibit 6. Completed green infrastructure cost summary.
Source: Columbia Construction Company
E. BENEFITS
The developer of the Waltham Watch Factory
recognized that the adjacent Charles River
provides a valuable amenity that helps attract
residents and businesses to the project. Using
green infrastructure to improve the river's water
quality thus helps to protect one of the site's
inherent assets. The various green infrastructure
features filter pollution and reduce stormwater
flows into the river. A reduction of impervious
surface area along the river also helps improve
the stream bank and its value as a natural
habitat. The project achieved additional
environmental benefits by cleaning up a
contaminated site and reducing ambient air
temperatures during hot weather.
The green infrastructure at the Watch Factory
not only helps improve the Charles River but also
is an amenity for building tenants and visitors
who enjoy the refurbished courtyards. The
project helped to increase public awareness of
Exhibit 7. The Waltham Watch Factory redevelopment
created an amenity for residents and visitors who can
now enjoy views of and access to the Charles River.
the Charles River and the role green
infrastructure can play to help protect it.
Boardwalks and pedestrian paths now allow the
public to reach the river's edge, increasing the
value residents place on this vital asset for the
city.
16 Bruner/Cott. "The Watch Factory." http://brunercott.com
/Pro1ect_shts_round_03/Pro1ect%20Sheets%20PDF_Commerci
al/BC_pro1_sht_watch_factory.pdf. Accessed Sep. 2, 2015.
17 Watch City Ventures LLC. "Team." http://www.waltham
watchf actory. com /team. Accessed Sep. 15, 2015.
12
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F. LESSONS LEARNED
Screening for soil contamination that could
limit the ability to infiltrate stormwater
should occur before project design to
identify areas suitable for green
infrastructure. Designers had to reconfigure
the project after initial planning, reducing
the expected benefits.
• Green infrastructure can be effectively
integrated into an historic property,
enhancing a project's aesthetic appeal. The
gardens and green space incorporated into
the project help highlight the connections
between the river as a valuable community
asset and development that protects and
preserves it.
G. PROJECT TEAM
• Owner: Watch City Ventures, LLC, a joint
venture between Berkeley Investments, Inc.,
and The First Republic Corporation of
America
• Developer: Berkeley Investments, Inc.
• General contractor (phase 1): Columbia
Construction Company
• Architect: Bruner/Cott & Associates
• Landscape architect: Richard Burck
Associates, Inc.
• Civil engineer: BSC Group, Inc.
• Environmental and geotechnical engineer:
Haley Aldrich
• Watershed advisor: Charles River Watershed
Association
• Environmental consultant: Pine & Swallow
Associates
Historic resource consultant: Epsilon
Associates18'19'20
Exhibit 8. Green infrastructure in the Watch Factory
courtyards provides an attractive view for residents and a
place to gather.
18 Reed and Bowditch op. cit.
19 Eckman, Eric. "The Redevelopment of the Historic
Waltham Watch Factory." The Weathervane. 2009.
http://docizz.com/preview/63472744.html.
20 Schneider, Jay W. "The Watch Factory, Waltham, Mass."
Building Design + Construction. Oct. 14, 2010.
http: / /www. bdcnetwork. com /watch-factory-waltham -mass.
13
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III. QUEENS
BOTANICAL
GARDEN
FLUSHING, NEW YORK
A new botanical garden visitor center and administration
building demonstrates the feasibility of incorporating
environmentally sustainable features into public buildings
while educating visitors about stormwater management.
Project type: Public building
Green infrastructure
Bioswales, cleansing biotope, green roof, artificial stream, and cisterns
Completion date: 2007
The Queens Botanical Garden's new visitor
center and administration building is a $14
million public project that showcases sustainable
design and green infrastructure. As a pilot
project for the New York City Department of
Design and Construction's High Performance
Building Program, it paved the way for new
green building requirements for city-funded
projects. In 2008, it became the first building in
New York City to earn a Leadership in Energy and
Environmental Design (LEED) Platinum rating
from the U.S. Green Building Council for new
construction, providing a public example of
successful sustainable design. One of the main
project goals was to eliminate stormwater
discharges to the city's combined sewer system.
The project uses a combination of green
infrastructure practices that both educate
visitors and manage and treat stormwater on-
site. The building also integrates several other
environmentally sustainable practices, including
grey water21 recycling through a constructed
wetland, stormwater infiltration through
permeable pavers in the parking area, and
renewable energy.
21 Grey water is wastewater generated from building fixtures
not including toilets—in this case, sinks, dishwashers, and
showers.
14
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A. SITE CONTEXT
The Queens Botanical Garden is in Flushing,
Queens, in New York City (Exhibit 9). From the
time of European settlement in the 1600s
through the 1800s, the area was primarily
agricultural, with the Flushing River providing a
route for shipping products to market. However,
in the 20th century, the area became a dense
residential and commercial area with new
bridge, subway, and rail connections to
Manhattan.22
The site was a construction dumping ground for
two World's Fairs. Soils at the site consist of
urban fill covered by approximately 6 feet of
imported soil. In addition, construction of the
1964 World's Fair filled in Mill Creek, a low-lying
wetland that was a tributary to the Flushing
River and once ran through the site.23 The site
was once a brownfield, but contamination from
past uses has been remediated.
The surrounding neighborhood is a lower-income
area with relatively few natural areas. The
Exhibit 9. The Queens Botanical Garden is in a dense
residential and commercial area.
garden gives the neighborhood much-needed
green space.
B. PLANNING AND REGULATORY PROCESS
The renovation of the Queens Botanical Garden
visitor center and administration building was a
pilot project for the New York City Department
of Design and Construction's High Performance
Buildings Program, which had the goal of making
new and renovated public buildings in the city
environmentally sustainable.24 The process began
in 1999 with a series of public workshops. They
helped establish the design framework for the
new building, which occupies approximately
4 acres in the 35-acre garden. Community
members and staff helped identify water as a
key element of the project that could help
connect people with nature. Because clean,
fresh water is important to cultures from around
the world, the Botanical Garden wanted to
illustrate the varied relationships people have to
water for the diverse population that visits the
garden, more than 75 percent of whom speak a
language other than English at home.25
C. DESIGN AND PERFORAAANCE
The garden's 2002 master plan set the goal of
achieving zero stormwater runoff to avoid any
discharge to the city's combined sewer system.
22 Conservation Design Forum and Atelier Dreiseitl. Master
Plan. Queens Botanical Garden. 2002. http://www.queens
botanical.org/103498/sustainable/master_plan.
23 Ibid.
This goal was more stringent than city
regulations called for but in keeping with the
Botanical Garden's vision of highlighting the
24 Bernstein, Fred A. "A Garden Blooms in Queens."
Metropolis Magazine. 2008. http: //www. metropolismag.
com/February-2008/A-Garden-Blooms-in-Queens.
25 Conservation Design Forum and Atelier Dreiseitl op. cit.
15
-------
importance of sustainable water resource
management in cities.26
Multiple best management practices ensure that
stormwater is retained on-site for all but the
largest storms (Exhibit 10). Practices include
permeable and semi-permeable surfaces to
reduce runoff volume and water storage and
treatment facilities for what remains. The visitor
center and administration building has a 3,000-
square-foot green roof over half of the structure.
Excess runoff from the other half of the roof and
adjacent walkways flows to a cleansing biotope,
a highly permeable three-layer substrate of sand,
gravel, and mineral additives, where soil and
roots from native plants filter stormwater.
Filtered water collects in a basin and fills a
24,000 gallon cistern, which feeds a fountain at
the Botanical Garden's main gate. From the
fountain, water flows through an artificial
meandering stream back to the basin, creating a
closed-loop system. Storm events that exceed
the capacity of the cistern and stream overflow
to a large bioswale where runoff infiltrates or
evaporates. Only the largest storms overflow into
the city's combined sewer system. The stream
runs dry during times of very low precipitation,
as a natural system would.27
A smaller stormwater cistern for washing
vehicles and building maintenance was
constructed in the service area in the back of the
building. In addition, stormwater runoff from
parking areas either infiltrates through
permeable pavers or flows to adjacent
bioswales.28 Together, the stormwater
management practices annually treat and/or
infiltrate approximately 628,000 gallons of runoff
from 34,000 square feet of contributing area,
74 percent of which is impervious cover.29
Main pedestrian entrance
New plaza and watercourse
leading to fountain
Existing allee
Constructed wetland
Native plant gardens
•«://l«f'
4
«*'*$
6. Green roof
7. Service area
a
8. Photovoltaic panels g
9. Covered terrace
10. Cleansing biotope
Exhibit 10. Queens Botanical Garden visitor center and administration building site plan.
D. COSTS AND FUNDING
Project costs for stormwater management are
difficult to isolate because water resource
management and associated public education
were integral components of the entire project.
The total cost for the visitor center and
administration building was $14 million,30 with
26 Ibid.
27 Bernstein op. cit.
28 Conservation Design Forum and Atelier Dreiseitl op. cit.
29 Atelier Dreiseitl. Rainwater System Overview. 2003.
30 Bernstein op. cit.
16
-------
the stormwater features accounting for about
$568,000, or 4 percent of total costs.31
Most of the project was funded by the Office of
the Borough President of Queens, with additional
support from the Office of the Mayor, the New
York City Council, several state agencies, and
several foundations.
E. BENEFITS
By serving as a pilot project under New York
City's High Performance Buildings Program, the
Queens Botanical Garden helped establish the
feasibility of environmentally sustainable public
buildings and pave the way for future legislation
requiring new construction funded by the city to
achieve a minimum LEED certification level.32
The project integrates environmental education
into its design, helping to demonstrate to its
hundreds of thousands of annual visitors the
importance of responsible stewardship of water
resources. The building and outdoor spaces are
used for professional and school group tours,
public programs, festivals, private event rentals,
local club meetings, community board meetings,
and as a voting location during elections.33 In
addition, the project helped the garden establish
and run a grant-funded green jobs training
program in partnership with LaGuardia
Community College.34 The program prepares
graduates for careers in green cleaning and
waste management and building operations and
maintenance.35
Stormwater runoff to the combined sewer system
from the site has been eliminated for all but the
largest storms, preventing more than 600,000
gallons from entering the system annually.36
Instead, stormwater irrigates the Botanical
Garden's plants and helps create a natural
environment for the public to enjoy in a lower-
income neighborhood with relatively few natural
areas.
Exhibit 11. The space outside the administration building
hosts performances and festivals.
F. LESSONS LEARNED
• Pilot projects can test the effectiveness of
stormwater management practices and
introduce new concepts to the design
community, regulators, and the public,
ultimately leading to policy changes. The
Queens Botanical Garden demonstrated the
feasibility of incorporating environmental
sustainability into public buildings, leading to
new city requirements.
Green infrastructure can be a focal point of a
building's design, helping to reestablish long-
severed connections between the natural
environment and residents.
31 Personal communication with Julie Nelson, BKSK
Architects, on Apr. 20, 2011.
32 City of New York. "Local Law 86 Basics." http://www.nyc
.gov/html/oec/html/green/U86_basics.shtml. Accessed Aug.
18,2015.
33 Personal communication with Julie Nelson, BKSK
Architects, on Nov. 18, 2015.
34 Ibid.
35 Green Jobs Training Program. "Home." http://greenwork
forcenyc.org. Accessed Nov. 20, 2015.
36 Atelier Dreiseitl op. at.
17
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G. PROJECT TEAM
Owner: Queens Botanical Garden
Developer: City of New York Department of
Design and Construction
Landscape and water design: Atelier
Dreiseitl
Landscape architect: Conservation Design
Forum
Architect: BKSK Architects
Civil and structural engineers: Weidlinger
Associates
Mechanical, electrical, and plumbing
engineers: P.A. Collins, PE37
Exhibit 12. The covered terrace where people gather
overlooks the cleansing biotope.
37 Queens Botanical Garden. "Project Team."
http://www.queensbotanical.org/103498/sustainable/
ParkingGarden_pro1ect/proiect_team. Accessed Aug. 17,
2015.
18
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"Wynne wood
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Philadefphi
IV. KENSINGTON
CREATIVE AND
PERFORMING ARTS
HIGH SCHOOL
PHILADELPHIA, PENNSYLVANIA
A new public high school on a former brownfield site becomes
a showcase for environmental sustainability and a valued
asset for the entire community.
Project type: Public building; brownfield redevelopment
Green infrastructure Rain gardens, green roof, permeable pavement, rainwater cisterns,
practices: vegetative filter strips, and underground detention basins
Completion date: Opened September 2010
Beginning in 2002, the nonprofit organization
Youth United for Change began a push to break
up the 1,400-student Kensington High School into
four smaller schools that could be more
responsive to student needs.38 One of those
schools would become the Kensington Creative
and Performing Arts (KCAPA) High School in 2005.
Students, parents, and community members
successfully advocated for a new school building
that would be a model of environmental
sustainability.
In 2010, the KCAPA High School opened as the
first public high school in the United States to be
certified LEED Platinum.39 Rain gardens, a green
roof, porous pavement, vegetative filter strips,
rainwater cisterns, and underground detention
basins capture all stormwater on-site for reuse in
irrigation and toilet flushing. Redevelopment of
the 7.2-acre, formerly contaminated site turned
a dangerous eyesore into a green amenity for the
neighborhood and spurred redevelopment that
incorporates green infrastructure on adjacent
properties.
38 Klonsky, Joanna. "Youth United for Change Takes on
Philadelphia's Public Schools." What Kids Can Do, Inc.
http://whatkidscando.org/featurestories/040107_YUC/index.
html. Accessed Apr. 16, 2015.
39 Delaware Valley Green Building Council. "Kensington High
School for the Creative and Performing Arts." http://www.
dvgbc.org/green_resources/proiects/kensington-high-school-
creative-and-performing-arts. Accessed Apr. 28, 2015.
19
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A. SITE CONTEXT
The project site is between the revitalizing
Fishtown neighborhood and the working-class,
industrial neighborhood of South Kensington. The
community wanted the school to help bring these
neighborhoods together by creating a center
where all could gather. The school district chose
not to fence in the school,40 allowing the
community to get to the gym, cafeteria, and
auditorium directly from the outside. Separate
lobbies and mechanical systems facilitate after-
hours use. Green infrastructure helped meet the
community's goal to have an environmentally
sustainable school that also is a neighborhood
amenity. Extensive native plantings incorporated
into stormwater management practices make the
front of the school look like a neighborhood park
and help make the school welcoming to
residents.41
The school's 7.2-acre site is a narrow lot
alongside a noisy elevated railway, and it
presented several challenges for redevelopment.
Contamination with lead, arsenic, and
polyaromatic hydrocarbons from past industrial
uses, including a former rail depot, had to be
cleaned up.42 The site had essentially been
abandoned, attracting homeless people, drug
dealers, and stray dogs.43 It had the reputation
of a dangerous place, and the community wanted
to improve it.
Exhibit 13. The KCAPA project site is a narrow lot
surrounded by compactly developed neighborhoods.
B. PLANNING AND REGULATORY CONTEXT
In 2009, the Philadelphia Water Department
launched Green City, Clean Waters, a plan to
invest $2 billion in green infrastructure over 25
years to manage stormwater and protect the
area's watersheds while revitalizing the city and
achieving other environmental, social, and
economic benefits.44 Schools make up 2 percent
of all impervious cover in the city's combined
sewer service areas, and their high visibility
makes them good opportunities for educating the
community about the benefits of green
40 Ibid.
41 ArchDaily. "The Kensington Creative and Performing Arts
High School / SMP Architects and SRK Architects." Nov. 30,
2011. http://www.archdailv.com/187671/the-kensington-
creatiVe-and-performing-arts-high-school-smp-architects-and-
srk-architects.
42 Rath, Jane, and Travis Alderson. "Champion for Change."
High Performing Buildings. Winter 2013. pp. 6-18.
http://www.hpbmagazine.org/Case-Studies/Kensington-
High-School-for-the-Creative-and-Performing-Arts-
Philadelphia-PA.
infrastructure.45 The Philadelphia Water
Department helped advance the KCAPA project
as one of the first in the city's Green Schools
program, a component of Green City, Clean
Waters.
Redevelopment projects disturbing more than
15,000 square feet of land must comply with the
city of Philadelphia's 2006 stormwater
management regulations that set requirements
for water quality, channel protection, flood
43 American Institute of Architects. "Kensington High School
for the Creative and Performing Arts." http://www.aiatopten
.org/node/48. Accessed Apr. 29, 2015.
44 City of Philadelphia. "Target 8: Manage Stormwater To
Meet Federal Standards." http://www.phila.gov/green/2011-
progress-report/equity-targetS.html. Accessed Apr. 20, 2015.
45 Philadelphia Water Department. Amended Clean City,
Clean Waters: The City of Philadelphia's Program for
Combined Sewer Overflow Control. 2011. http://www.philly
watersheds. org/doc/GCCW_AmendedJune2011_LOWRES-web.
fidf.
20
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control, and non-structural site design.46
However, this project was exempt from the
channel protection requirement because it is in
the Delaware River watershed.47 Exhibit 14
summarizes the relevant requirements and the
stormwater practices used to help meet each
requirement.
DESCRIPTION
Water quality
To recharge groundwater, restore natural site hydrology, reduce
pollution in runoff, and reduce combined sewer overflows, the first
inch of rainfall must be infiltrated on-site. Where infiltration is not
appropriate or feasible, 100 percent of the runoff from directly
connected impervious surfaces must be slowly released into the sewer
system with 20 percent routed through an approved stormwater
management practice to improve water quality.
RACTICES IMPLEMENTED
Porous pavement
Rain gardens
Green roof
Vegetative filter strips
Water quality inflow structures
leading to underground storage
Flood control
To reduce flooding downstream of the development site and to
reduce combined sewer overflows, peak runoff after development
must not exceed peak runoff before development. Exact requirements
depend on the flood management district in which the project is
located. This project was required to reduce the 2-year storm event
post-development peak flow rate to less than the 1-year storm event
pre-development peak flow rate, and maintain post-development
rates below pre-development rates for the remaining storms.
Porous pavement
Rain gardens
Green roof
Underground detention
Public health
and safety
To limit discharges to the combined sewer system, which has limited
capacity, each of the sub-drainage areas must have a release rate no
greater than 0.35 cubic feet per second per acre for up to the 10-year
storm.
Porous pavement
Rain gardens
Green roof
Vegetative filter strips
Underground detention
Non-structural
site design
To reduce the quantity of stormwater that must be managed, projects
must minimize creation of impervious cover and protect and use
existing site features with natural stormwater management value.
Efficient walkway layout
Smaller building footprint
Grass-turf pavers in loading
and emergency access areas
Exhibit 14. Philadelphia stormwater regulations applicable to the project.
C. DESIGN AND PERFORMANCE
Soil contamination on the site made
incorporating sufficient green infrastructure to
meet stormwater management requirements
challenging. Designers had to avoid infiltration
in certain areas, but they maximized
infiltration where appropriate. Field infiltration
tests helped identify areas with soil conditions
most favorable for green infrastructure
practices. Measured infiltration rates ranged
from 0.13 to 8.25 inches per hour at varying
depths. The lowest rate used for infiltration
was 2.25 inches per hour at one of the porous
pavement areas. The rain gardens were sited in
an area with an infiltration rate of 4.65 inches
per hour. Soils near the playing fields and the
fire lane had poor infiltration rates, so
underground storage was used with water
quality inflow structures to pretreat the runoff.
Exhibit 15 provides the amount of directly
connected impervious area (DCIA) drained, the
amount of water treated (WQv), and the
storage volume for each type of practice.
46 City of Philadelphia. Stormwater Management Program.
2007. http://www.phillywatersheds.org/doc/2007_AnnuaL
Report_Final.pdf.
47 City of Philadelphia. Stormwater Management Guidance
Manual Version 2.1. 2014. http://www.pwdplanreview.org/
manual-info/pre-luly-2015-resources.
21
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STORMWATER
PRACTICE
Porous pavement
Pretreatment and
underground storage
Rain gardens
Green roof
Total
TYPE OF PRACTICE
Infiltration
Treat and release
Infiltration
Retention/evapotranspiration
TOTAL DCIA
(SQUARE FEET)
40,730
66,080
8,580
22,040
137,430
WQV (CU
REQUIRED
3,393
5,507
715
824
10,439
BIC FEET) STORAGE
PROVIDED (CUBIC FEET)
5,482
5,507
2,193
824
14,006
24,706
41,660
4,507
4,010
74,883
Exhibit 15. Stormwater best management practices performance.
All infiltration practices were designed to handle
their entire contributing drainage area for the
100-year storm, exceeding the requirements for
public health and safety in combined sewer
areas. Rain gardens were designed to intercept
runoff from landscaped areas as well. Finally,
the underground storage reduces post-
development peak flow rates by 74 percent,
54 percent, and 33 percent for the 15-, 50-, and
100-year storms, respectively, compared to pre-
development peak flows.
Two underground rainwater cisterns provide
water for toilet flushing, although the
seasonally of high school occupancy limits their
effectiveness in managing stormwater runoff.
Overflow from these cisterns is directed to one
of the underground detention basins.
Because the project engineers worked closely
with the Philadelphia Water Department on the
design for this project, they were able to use
new piping materials that the old code did not
initially allow, resulting in cost savings and a
better design.48
The school opened to students in September
2010. Five years after installation, the green
infrastructure practices continue to function
well. The permeable pavement surfaces are in
good condition, and the vegetation is healthy.49
Routine school maintenance incorporates upkeep
of the green infrastructure practices along with
more conventional landscaped areas.50
6. Permeable paving
7. Porous grass paving
8. Rain garden
9. Elevated transit station
. Green roof
2. Cool roof rain water collection
3. Outdoor classroom
4. School garden
5. Recycled landscape
Exhibit 16. The site plan for KCAPA incorporated green infrastructure in multiple places.
48 American Institute of Architects op. cit.
49 Personal communication with Ronald Monkres, Gilmore &
Associates, on Oct. 20, 2015.
50 Personal communication with Ronald Monkres and Chris
Green, Gilmore & Associates, on Feb. 11, 2011.
22
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D. COSTS AND FUNDING
The School District of Philadelphia chose to
construct KCAPA as a "turnkey" project, wherein
a private developer purchased and cleaned up
the land, built the school, and financed most of
it through a local bank, turning the project over
to the school district at completion for a set
price.51 The funding source for the $44 million
project52 was initially private, but the project
later became a public-private partnership with
the infusion of public funds, including $1 million
from the Pennsylvania Department of
Environmental Protection for a geothermal
heating and cooling system.53 The stormwater
management practices cost about $1 million, or
about 2.5 percent of total project costs.54
E. BENEFITS
Managing stormwater on-site with a combination
of green infrastructure and underground storage
reduces runoff and pollution entering the area's
combined sewer system. The reduction in
impervious cover reduces the site's stormwater
fees, and rainwater harvesting and low-flow
plumbing fixtures reduced projected municipal
water use by 65 percent, with no water required
for irrigating landscaping.55 Overall, 69 percent
of the site is green space due to compact
building design and a geothermal HVAC system,
which reduced the space needed for the
mechanical systems.56
The environmental benefits of the school's green
infrastructure extend beyond the site because it
generated interest in expanding the practices
used at the school to other places in the
community. The New Kensington Community
Development Corporation led a project to add
green infrastructure to an adjacent recreation
center, and that in turn led to green
infrastructure improvements along the
neighboring street.57 In addition, the school's
green roof and rain gardens are visible to the
thousands of commuters passing by daily on the
elevated rail line, helping to demonstrate the
Exhibit 17. Riders of the elevated rail line can see the rain
gardens in front of KCAPA as they pass by daily.
aesthetic value of green infrastructure to the
community.
The school's location also created environmental
benefits independent of the building design. Not
only is a former contaminated industrial site now
cleaned up, creating space for children's sports
and community gardens,58 but transportation-
related emissions are low. A/tare than 95 percent
of building occupants travel to school by walking,
biking, or taking public transportation, including
the elevated rail line that runs along the school
property. The community uses the elevated rail
51 American Institute of Architects op. cit.
52 BSI Construction. "Kensington High School for the Creative
and Performing Arts." http: / /www. bsiconst. com /projects/
case-studies/kensington-capa. Accessed Sep. 2, 2015.
53 Rubin, Daniel. "Philadelphia District Wins a Green-Schools
Award." Philly.com. Dec. 12, 2011. http://articles.philly.
com/2011-12-12/news/30507242_1_green-schools-green-
roofs-green-cleaning-products.
54 Personal communication with Ronald Monkres, Gilmore &
Associates, on Oct. 19, 2015.
55 Rath and Alderson op. cit.
56 Eco-structure Staff. "Kensington High School for the
Creative and Performing Arts." Ecobuilding Pulse. Aug. 14,
2012. http://www.ecobuildingpulse.com/award-winners/
cote-2012-top-ten-kensington-high.aspx.
57 Rath and Alderson op. cit.
58 American Institute of Architects op. cit.
23
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stop more, helping to revitalize the
neighborhood.59
Student engagement and performance at KCAPA
improved after moving to the new building. In
the first year of operation, the school had a
waiting list to attend, while truancy rates fell
and both test scores and the graduation rate
went up.60 School staff have also noticed less
littering and vandalism at the new school as
students take pride in the building and become
stewards of the space.61
F. LESSONS LEARNED
• Green infrastructure can be used successfully
on a contaminated site where only part of
the site is suitable for infiltration. Careful
site design based on soil testing allowed
designers to maximize infiltration by placing
green infrastructure in the most suitable
locations.
• Less than one-third of the parking built at
the school (required by zoning) is being used.
The developers did not pursue a zoning
variance because of the time required. The
school could have used the half-acre of
unneeded parking space for additional green
space or other uses if Philadelphia's zoning
required less parking for properties near
public transit in walkable neighborhoods.62
Often, school districts feel pressure to
eliminate environmentally sustainable
features when budgets are tight, but
constructing the project with a "turnkey"
delivery allowed the developer to use
sustainable features as long as it could meet
the overall budget and schedule.
Constructing the school with a smaller
footprint ultimately saved enough money to
pay for the green features.63
G. PROJECT TEAM
• Owner: The School District of Philadelphia
• Design: SMP Architects and SRK Architects
• Engineering: Gilmore & Associates
• Construction: AP Construction and Bustleton
Services, Inc.64
59 Rath and Alderson op. cit.
60 Eco-structure Staff op. cit.
61 Personal communication with Ronald Monkres, Gilmore &
Associates, on Oct. 19, 2015.
62 Rath and Alderson op. cit.
63 American Institute of Architects op. cit.
64Stabert, Lee. "Learning Curve." Grid. Nov. 2010.
http://issuu.com/redflagmedia/docs/grid_2010.11?e=126199
5/5375442#search.
24
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V. THE RADIAN
COMPLEX
PHILADELPHIA, PENNSYLVANIA
A new mixed-use building on a
university campus uses a green
roof system to meet stormwater requirements while
maximizing developable space, creating an amenity for
residents and businesses.
Project type: Mixed-use development
Green infrastructure Green roof, pervious pavers, tree pits and planters, and stormwater
practices: detention basins
Completion date: 2009
The University of Pennsylvania and a private
developer built a new mixed-use building with
retail and student apartments. The site at the
edge of the University's Philadelphia campus had
existing structures and was 99 percent
impervious. Using green infrastructure, they
achieved a 30 percent reduction in impervious
area draining to the combined sewer system.
New trees and a green roof are now selling
points for the commercial and residential
tenants. Although the site is highly constrained,
the developer was able to meet stormwater
management requirements for green
infrastructure while maximizing the developable
area of the site.
A. SITE CONTEXT
The Radian Complex is a 14-story, 500-bed
student housing and retail center on Walnut
Street at the northwestern edge of the University
of Pennsylvania campus (Exhibit 18). The project
is part of continuing campus development along
the 40th Street corridor, which links the
university to West Philadelphia. A project
65 Wisniewski, Katherine. "Radian Apartments/Erdy McHenry
Architecture." Arch Daily. Aug. 15, 2011.
combining student housing and neighborhood-
serving retail helps to link these two areas of the
city.65
Before construction, the project site was
99 percent impervious, sending nearly all
stormwater runoff into the city's combined
sewer system. The site is in the Schuylkill River
http://www.archdaily.com/158386/radian-apartments-erdy-
mchenry-architecture.
25
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watershed. Reducing combined sewer overflows
into the Schuylkill River is a critical step for
meeting water quality standards and keeping
aquatic life healthy.66 However, other buildings
and infrastructure near the project site limited
the opportunity for infiltration.
B. PLANNING AND
REGULATORY CONTEXT
On January 1, 2006, the city of Philadelphia
Water Department instituted new stormwater
management regulations, providing guidelines for
achieving water quality and managing runoff.67
This project was one of the first to have to meet
the new requirements.
The regulations require redevelopment projects
to reduce predevelopment runoff volumes by at
least 20 percent based on the following:
• All non-forested, pervious areas are
considered meadow (in "good" hydrologic
condition).
• In addition, 20 percent of existing impervious
cover on-site is also considered meadow.
Exhibit 18. The Radian Complex sits on the edge of the
University of Pennsylvania's campus along a commercial
corridor.
The site must also infiltrate on-site, or if soils do
not permit, store and treat on-site the
stormwater volume equal to the first inch of
rainfall over all directly connected impervious
areas.
C. DESIGN AND PERFORAAANCE
To help meet the stormwater requirements while
maximizing the ground-floor space available for
retail, designers used a 12,000-square-foot green
roof system that covers 17 percent of the site. In
addition, 4,700 square feet of adjacent
conventional roof area, covering an additional
6 percent of the site, drains to the green roof
system, allowing the project to exceed the
required 20 percent reduction in impervious
cover.68 The system includes five green roofs.
Three extensive roofs are designed to hold the
first inch of runoff. Two intensive roofs are
designed to hold the first 2 inches of runoff.
Together, they treat the first inch of runoff for
16,700 square feet, meeting water quality
requirements. The green roof system maximizes
water retention on the roof and controls the
release rate into two underground stormwater
management basins to meet the city's channel
protection and flood control requirements.
Even with the reduction in impervious cover
afforded by the green roof, the project's design
still had to manage stormwater runoff from the
rest of the project site. The project's retail
plaza incorporates interlocking permeable
66 Philadelphia Water Department. Green City Clean Waters.
2011. http://vwvw.phillywatersheds.org/doc/GCCW_
AmendedJune2011_LOWRES-web.pdf.
67 Philadelphia Water Department. Stormwater Regulations,
§600.0 Stormwater Management. 2006.
68 Pockl, Andrew, and Corey Fenwick. "More than Just a
Pretty Garden." Stormwater Solutions. Nov./Dec. 2007.
http://estormwater.com/More-Than-Just-a-Pretty-Garden-
article8747.
26
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concrete pavers and tree pits. Stormwater is
directed first into planters that provide some
water storage in a layer of stone below the soil.
Excess water collects in an underdrain and flows
through tree pits to one of two underground
detention basins. The basins are constructed
from "milk crate" type structures covered with
gap-graded stone placed within an impermeable
geotextile liner. The detention basins are
designed to collect the overflow from a 100-year
storm and slowly release it to the combined
sewer system at a controlled rate.69
The project reduced directly connected
impervious area by 30 percent using a
combination of a green roof, pervious pavers,
planters, and tree pits, as described in Exhibit
20. In addition, an outdoor dining space on the
Exhibit 19. The green roof system on the Radian
Complex diverts Stormwater from the combined sewer
system while giving residents an attractive view.
upper terrace level with views of the street
includes a grove of trees separating the retail
and residential components.
STORMWATER MANAGEMENT PRACTICE
Green roof area
Conventional roof area draining to green roof
Pervious pavers
Planter boxes
New trees
Total
SQUARE FEET PERCENT OF SITE
12,091 (650 intensive; 11,441 extensive)
4,022
2,155
1,470
900
20,638
17.8%
5.9%
3.2%
2.2%
1.3%
30.3%
Exhibit 20. Reduction in directly connected impervious area for Stormwater management practices.
D. COSTS AND FUNDING
This project was privately funded on land
owned by the University of Pennsylvania.
Excluding the cost of landscaping, the green
roof, porous pavement, planters, tree pits, and
detention basins together cost $377,000, or
0.5 percent of the total project cost of $70.2
million (Exhibit 21). The green roof was the
most costly element of the Stormwater
management system, but it allowed the project
to meet Stormwater management regulations
while maximizing the area available for retail.
Annual operations and maintenance costs are
estimated to be about $6,000 based on price
quotes submitted to the engineers for the
project. These costs include routine inspections
of sumps in all inlets and roof drains for debris
removal, inspection of outlet structures on the
underground detention basins after all major
storms for removal of silt and debris, inspection
of pervious pavers, and sweeping to remove
debris.
69
Ibid.
27
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FEATURE QUANTITY UNIT COST COST
Green roof, including protection layer, drainage media, perforated pipes,
soil, and plantings
Pervious pavers, including site preparation, gravel base, and underdrain pipes
Stormwater drainage system, including detention basins and piping
Total
12,000ft2
2,150ft2
n/a
$14 per ft2
$25 per ft2
n/a
$165,000
$53,500
$158,500
$377,000
Exhibit 21. Construction cost summary. Costs for the green roof do not include elements that are part of a conventional roof
such as the roof structure and waterproofing, which add approximately $15 per square foot.
Source: Pennoni Associates.
E. BENEFITS
This project reduced the amount of impervious
surface area at the project site by 30 percent,
exceeding regulatory requirements and reducing
runoff flowing to the city's combined sewer
system. The primary component of the
stormwater management system, the green roof,
creates an attractive view for the student
apartments and retail businesses that can see it,
allowing the project owner to charge higher rent
for the retail area overlooking the green roof.
The tree planters on the sidewalk and courtyard
next to the retail area create an additional
aesthetic amenity for the neighborhood.
The use of a green roof allowed the owner to
maximize the available space for retail while
meeting stormwater management requirements,
supporting the overall business environment in
the neighborhood. The ground-level retail
extends along the entire block on the 40th Street
Exhibit 22. Retail space on the first floor of the Radian
Complex helps bring activity to the commercial corridor.
retail corridor, serving both the university and
the adjacent residential neighborhood. Since the
building opened, additional development has
occurred in the immediate area, and restaurants
and businesses are thriving.70
F. LESSONS LEARNED
• Even relatively expensive green
infrastructure practices like green roofs can
be economically viable when they allow
project developers to meet stormwater
requirements while maximizing developable
area on a site. Higher costs with some green
infrastructure practices can be offset by
reduced construction and maintenance of
conventional stormwater infrastructure and
by the ability to command higher prices for
the property due to the green infrastructure.
Water quality improvements are possible
even on properties in highly developed areas
where soils are not conducive to infiltration.
The Radian Complex used a green roof to
meet requirements for managing stormwater
on-site at a location where other buildings
and infrastructure limited options.
70 Personal communication with Andrew Pockl, Pennoni
Associates, on Nov. 13, 2015.
28
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G. PROJECT TEAM
• Owner: University of Pennsylvania.
• Developer and manager: University Partners
• Civil engineers and landscape architects:
Pennoni Associates
• Architects: Erdy McHenry Architecture, LLC
• Structural engineer: The Harman Group
• Green roof consultant: Roofscapes
• Exterior wall consultant: Edwards &
Company
• Contractor: INTECH Construction, Inc.71
71 Erdy McHenry Architecture, LLC. "The Radian." Architype
Review. 2008. http://architvpereview.com/proiect/the-
radian/?issue_id=561.
29
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VI. SAND RIVER HEADWATERS
GREEN INFRASTRUCTURE
PROJECT
AIKEN, SOUTH CAROLINA
A downtown project incorporating
green infrastructure into public
spaces enhances a small town's
historic charm while helping to
preserve a beloved urban forest
and restore a degraded river.
Project type: Transportation; historic preservation
Green infrastructure Rain gardens, bioswales, porous asphalt, pervious concrete, permeable
practices: interlocking concrete pavers, and underground cisterns
Completion date: 2011
Over decades, stormwater eroded a 70-foot-deep
canyon below the Aiken, South Carolina,
stormwater outfall (Exhibit 23). The banks of the
Sand River destabilized, destroying vegetation
and choking downstream wetlands with sediment
as they collapsed. The city chose a restoration
plan for the Sand River that focuses on upstream
reduction of stormwater runoff through green
infrastructure in downtown Aiken, including
bioswales, porous asphalt, permeable pavers,
and rain gardens. The city chose this approach as
the most cost-effective way to remedy
environmental degradation that could also
improve the city's historic parkways and
boulevards with wide, landscaped medians.
Exhibit 23. Stormwater has eroded a deep canyon in the
banks of the Sand River.
30
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A. SITE CONTEXT
Aiken is in western South Carolina near the
Georgia border. The city of approximately 30,000
people has one of the largest urban forests in the
country, a 2,100-acre public green space next to
Exhibit 24. Aiken's downtown is next to Hitchcock Woods,
which receives stormwater runoff from city streets.
downtown called Hitchcock Woods (Exhibit 24).
Through the forest flows the Sand River, an
ephemeral stream that runs dry between periods
of rain.
Downtown Aiken has 105 acres of 150-foot-wide
parkways and boulevards with landscaped
medians, giving the city a distinctive charm and
character. Stormwater runoff from the streets
originally flowed through open channels and a
relatively natural drainage system. That changed
in the 1950s, when the city paved the streets and
installed a conventional storm sewer system that
conveys stormwater to an outfall at the
headwaters of the Sand River.72 As impervious
cover has increased with new development,
stormwater runoff has eroded a 70-foot-deep
canyon in the Sand River, sending loose sand
downstream where it degrades forested
wetlands.73 The Sand River has been listed as an
impaired waterbody since 1998 for exceeding
standards for fecal coliform bacteria, with
stormwater runoff listed as a potential major
source of contamination.74
B. PLANNING AND REGULATORY CONTEXT
In 2008, the city awarded the Clemson University
Center for Watershed Excellence (Clemson) a
grant to develop a river restoration master plan.
Clemson convened a series of workshops and
meetings with the city, community members,
and other stakeholders to explore alternatives.
The preferred approach for river restoration
would cost approximately $16 million to $18
million, including remediation of the canyon and
wetlands, new pipes to convey flow below the
restored canyon, energy dissipation and storage
devices, and tributary stabilization. The parties
ultimately chose a strategy focused initially on
reducing runoff in the watershed through green
infrastructure to fix the root cause of the
problem. The city hopes this approach will
improve the flow conditions at the outfall and
potentially reduce the overall cost of the
downstream river restoration project.75
72 Eidson, G.W., et al. "Sand River Headwaters Green
Infrastructure Project, City of Aiken, South Carolina: A
Collaborative Team Approach to Implementing Green
Infrastructure Practices." Proceedings of the 2010 South
Carolina Water Resources Conference. Oct. 13-14, 2010.
73 Clemson University. Sand River Headwaters Green
Infrastructure Project. 2013. http://media.clemson.edu
/public/restoration/sand%20river/agi_finalreport_022113-
web.pdf.
74 South Carolina Department of Health and Environmental
Control. Total Maximum Daily Load Horse Creek (Hydrologic
Unit Code: 03060106060, -030, -040 & -050) Stations SV-069,
SV-072, SV-073 8 SV-250 Fecal Coliform Bacteria. 2005.
https://www. scdhec.gov/HomeAndEnvironment/Docs/tmdL
horse.pdf.
75 Clemson University 2013 op. cit.
31
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C. DESIGN AND PERFORMANCE
The Sand River Headwaters Green Infrastructure
Project includes multiple green infrastructure
practices installed near the intersection of Park
Avenue and Newberry Street in downtown Aiken.
City staff and residents were concerned that this
project would affect the general appearance of
the historic parkways and disturb existing mature
trees. To address this concern, designers chose
bioswales and rain gardens that complement the
existing parkway landscaping, using native plants
to blend in with the surroundings (Exhibit 25).
Water from adjacent roads and sidewalks flows
to the bioswales and rain gardens, which filter
out nutrients and bacteria, reduce peak
discharge flows, and recharge ground water.
Street improvements include porous asphalt;
pervious concrete; and permeable, interlocking
pavers in the parking lanes, which infiltrate
runoff from the adjacent road as well. Overflow
systems direct excess runoff to the existing
storm sewer system for large storm events.
Underground cisterns at several locations store
runoff for irrigation.76
In 2008, the city did not have regulations
specifying minimum design requirements for
green infrastructure practices. Therefore, the
practices are sized to meet the minimum
standard design criteria issued by the South
Carolina Department of Health and
Environmental Control in 2002, which include:
• Infiltration practices must capture and treat
the first inch of runoff from the contributing
impervious surfaces.
• Post-development peak flows from best
management practices must not exceed pre-
development discharge rates for the 2- and
10-year, 24-hour storm events.77
Exhibit 25. Rain gardens in street medians help manage
stormwater while providing attractive landscaping.
In addition to meeting these requirements, the
green infrastructure practices infiltrate at least
the 2-year, 24-hour storm event (approximately
3.7 inches) within 72 hours.78
The first phase of construction was completed in
February 2011. Monitoring equipment measures
the performance of the green infrastructure
practices as part of the online Clemson
University Intelligent River Program, which
displays real-time data. The program is an
educational tool that the community, educators,
and designers can view online.79 The data
include baseline measurements of stormwater
hydraulics before installation of the green
infrastructure practices to evaluate their impact.
Preliminary monitoring results indicate that in
many cases, the bioinfiltration practices are
infiltrating all stormwater runoff and discharging
none into the sewer system through the overflow
pipes. However, the Sand River watershed
overall showed no statistically significant
improvement, likely because the surface area of
the bioretention practices represented just
0.4 percent of the total watershed. All three
types of permeable pavement worked as
expected, with average infiltration rates
adequate for stormwater management.80
76 Ibid.
77 South Carolina Department of Health and Environmental
Control. Standards for Stormwater Management and
Sediment Reduction Regulation 72-300 thru 72-316. 2002.
https:/ /www. scdhec.gov/ Agency/docs/water-regs/r72-
300.pdf.
78 Clemson University 2013 op. cit.
79 Clemson University. "Intelligent River Data Browser for
Sand River, Aiken." https://www.intelligentriver.org/data
?p=7. Accessed May 14, 2015.
80 Clemson University 2013 op. cit.
32
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D. COSTS AND FUNDING
The city of Aiken was awarded $3.34 million
under the American Recovery and Reinvestment
Act of 2009 through the Clean Water State
Revolving Fund for design, construction, and
post-construction monitoring of green
infrastructure practices to control stormwater
runoff into the Sand River, the first phase of the
Sand River restoration master plan.81 The city
awarded two related grants to Clemson:
$293,187 for the design of the green
infrastructure practices and $126,359 for a
research and monitoring program.82
The city is responsible for the operation and
maintenance of the green infrastructure
practices installed as part of this project. The
city pays for those costs through a stormwater
utility fee assessed to city property owners.83
E. BENEFITS
The green infrastructure practices installed as
part of the master plan for restoring Sand River
complement the landscaping of the city's historic
parkways and boulevards. The city plans to use
similar approaches to improve stormwater
management in other parkways in and around
the city to revitalize neighborhoods and further
lessen the amount of stormwater the city
discharges to the Sand River headwaters.
The monitoring program established as part of
this project helps educate residents and leaders
in the city of Aiken and other communities,
educators, designers, and the scientific
community, providing valuable information on
the design effectiveness of green infrastructure
practices. In the first three years, more than
5,000 people viewed the website.84
F. LESSONS LEARNED
• Green infrastructure can complement and
enhance historic city landscapes. Residents
in Aiken were initially concerned about
possible damage to mature trees that lined
the city's parkways and boulevards, and they
did not want to detract from the city's
overall historic charm. Permeable pavement
and careful design of bioswales allowed
green infrastructure to enhance the city's
aesthetics.
• Green infrastructure in historic downtowns
can help protect natural areas that residents
cherish. The Aiken green infrastructure
project benefits Hitchcock Woods, a natural
area next to downtown that serves as a city
park and is central to the area's identity.
After residents understood the link between
downtown stormwater and the health of
their local ecosystem, they supported green
infrastructure as an innovative approach for
environmental protection.
G. PROJECT TEAM
• Owner: City of Aiken
• Engineering: Clemson University Center for
Watershed Excellence and Woolpert, Inc.
81 Ibid.
82 Greenville.com Community News. "Aiken, Clemson, EPA
Kick Off Project to Make Stormwater 'Green'." http://www.
greenville.com/news/epa0310.html. Accessed Sep. 3, 2015.
83 City of Aiken. Storm Water. 2015. https://www.cityofaiken
sc.gov/wp-content/uploads/downloads/2015/01/brochure,
stormwater.pdf.
84 Clemson University 2013 op. at.
33
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VII. MENOMONEE VALLEY
INDUSTRIAL CENTER
MILWAUKEE, WISCONSIN
A redeveloped industrial center
helps restart a region's
economic engine while creating
a stormwater park that
connects residents to the long-
isolated Menomonee River.
Milwaukee
- -
Project type: Office and industrial development; public park; brownfield redevelopment
Green infrastructure Comprehensive site planning; stormwater treatment train, including
practices: infiltration, settling, and detention; and subsurface treatment
r , ... , . Land improvements and stormwater facility completed in 2005; private
Completion date: , , . .. r-ir,^
development continues as of 2015
The Menomonee Valley Industrial Center (MVIC)
sits on a redeveloped former brownfield site with
an industrial past dating to the late 19th century.
The redevelopment involved remediating
contamination and returning the vacant site to
productive use as an economic engine that
generates more than $1 million a year in
property tax revenues and employs more than
1,400 people in a new industrial center. A
centralized green infrastructure stormwater
management system achieves both water quality
and volume reduction objectives for current and
future development while giving the community
a new recreational park that provides a new
access point to the Menomonee River.
Exhibit 26. The Milwaukee Road Shops were abandoned in 1985, leaving a contaminated site and an eyesore.
34
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A. SITE CONTEXT
MVIC is in the Menomonee River Valley region of
Milwaukee. The area was once covered with an
expansive wild rice marsh that sustained native
tribes for centuries. The Menomonee River is 75
miles long from its headwaters to Lake Michigan,
and its watershed is approximately 140 square
miles of urban landscape. Much of the river was
channelized in the late 1800s as the marsh was
filled to create land suitable for industrial
activities along its banks.85 A variety of
contaminants impair the river's water quality,
including pathogens, PCBs, phosphorus, and
metals. The MVIC site has been a major source of
such pollution to the river.
Industrialization of the area proceeded rapidly
after the incorporation of Milwaukee in 1846.
Industrial processing, manufacturing, stockyards,
rendering plants, and shipping came to dominate
the area.86 Beginning in 1879 and continuing for
more than 100 years, the MVIC site was home to
the former Milwaukee Road Shops, which built
and serviced railroad cars and locomotives. The
facility closed in 1985, and the area was
abandoned, leaving behind vacant, dilapidated
buildings and a host of contamination issues in
the underlying soils and groundwater (Exhibit
26).87 For years, unknown remediation costs
discouraged private-sector redevelopment of the
Exhibit 27. The MVIC site is located along the Menomonee
River in a compactly developed part of the city.
site. In 2003, the Redevelopment Authority of
the City of Milwaukee acquired the property and
prepared a comprehensive master plan for its
redevelopment.88 The plan called for the
demolition of existing infrastructure,
remediation of polluted areas, and the
redevelopment of the site into a new industrial
center and recreational park.
B. PLANNING AND REGULATORY CONTEXT
The city of Milwaukee recognized the MVIC site
as an important part of any economic planning in
the metropolitan area due to its central location,
proximity to existing transportation
infrastructure, and history as the region's
employment base. Employment in the
Menomonee Valley had fallen from about 50,000
people in the 1920s to just over 7,000 by 1997.89
85 Menomonee Valley Benchmarking Initiative. 2073
Menomonee Valley State of the Valley Report. 2014.
http://www.renewthevalley.org/documents/160-resource-
library.
86 City of Milwaukee. Menomonee Valley 2.0 Comprehensive
Area Plan. 2015. http: / /www. planthevalley. org/uploads/1 /9
/0/4/19044935/menomonee_vallev_plan_5-22-15_draft.pdf.
87 Misky, David P., and Cynthia L. Nemke. "From Blighted to
Beautiful." Government Engineering. May-June 2010.
In 1998, the city prepared a plan for the
redevelopment of the Menomonee Valley that
reflected the community's goals to attract and
retain industry; improve transit, biking, and
walking connections in the area; and add new
green space for improved aesthetics and flood
control.90
88 De Sousa, Christopher. Milwaukee's Menomonee Valley: A
Sustainable Re-Industrialization Best Practice. University of
Illinois at Chicago. 2012. http://www.uic.edu/orgs/
brownfields/research-results/documents/Menomonee
Valley.pdf.
89 Menomonee Valley Benchmarking Initiative op. cit.
90 Rouse, David, and Ignacio Bunster-Ossa. "Menomonee
Valley Park and Redevelopment, Milwaukee." In Green
Infrastructure: A Landscape Approach. American Planning
Association. 2013.
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In 2002, a national design competition for the
MVIC site led to implementation of a plan that
included industrial development adjacent to a
community park. "Stormwater Park"
incorporates a centralized stormwater
management facility that infiltrates, detains,
and treats stormwater runoff from approximately
70 percent of the 100-acre watershed prior to
discharge into the Menomonee River.
C. DESIGN AND PERFORMANCE
The project had to comply with surface water
and stormwater regulations established in 2001
by the Milwaukee Metropolitan Sewer District,
the City of Milwaukee Stormwater Management
Regulations, and the Sustainable Design
Guidelines for the Menomonee River Valley.91
A centralized stormwater facility meets or
exceeds water quality requirements for current
and future development in MVIC through a
restored landscape that mimics natural river
hydrology and improves water quality while
reducing peak stormwater flows. Runoff is first
collected and piped to a series of small ponds
that allow large particulates to settle before it
spreads out across a shallow wetland. Some of
the stormwater is evapotranspired through
meadow plants while the rest filters through the
soil into a 2-foot layer of crushed lime-based
concrete, recycled from a nearby highway
interchange project. This subsurface infiltration
area removes pollutants, provides additional
storage capacity for larger storm events, and
allows surface water to remain shallow enough
to support the growth of wetland plants. A clay
liner protects ground water. Stormwater then
flows through an outlet and a subsurface
treatment system to a constructed, forested
wetland. Any overflow from the wetland crosses
a stone river terrace leading to the Menomonee
River, allowing people direct access to the
river's edge for the first time in decades (Exhibit
28).92
Modeling indicates that the treatment system
reduced total suspended solids by 80 percent,
total phosphorus by 66 percent, total Kjeldahl
Exhibit 28. The MVIC Stormwater Park manages stormwater
runoff while providing a new public space with pedestrian
and bicycle trails.
nitrogen93 by 62 percent, petroleum
hydrocarbons by 76 percent, zinc by 62 percent,
copper by 62 percent, and lead by 76 percent.
The project is designed to contain the 2-year
storm event within the constructed stormwater
facilities and the 100-year storm within the
entire green space of Stormwater Park. To meet
the city's requirement to control peak flows
during a 100-year storm event, the stormwater
management facilities had to be created by
reshaping and filling the flood plain. An
innovative agreement with the Wisconsin
Department of Transportation allowed the MVIC
developers to use fill and recycled concrete from
a local highway reconstruction project. The site
reused 700,000 cubic yards of material that
otherwise would have been deposited in a
landfill, saving both projects a considerable
amount of money.94
As of 2015, Stormwater Park has successfully
handled several significant storm events and
91 Menomonee Valley Partners. Sustainable Design Guidelines
for the Menomonee River Valley. 2006. http: / /www. renew
thevallev.org/media/mediafile_attachments/06/46-
guidelines.
92 Rouse and Bunster-Ossa op. cit.
93 Total Kjeldahl nitrogen is the sum of free ammonia and
organic nitrogen compounds.
94 Misky and Nemke op. cit.
36
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continues to collect, hold, and filter rain water
as expected. Maintenance primarily involves
removing invasive species from the now-
established native vegetation planted on the
site. In addition, MVIC maintenance staff
occasionally check to see if any sediment needs
to be removed from the outlet channel to
maintain proper flow.95
D. COSTS AND FUNDING
The stormwater costs for the MVIC development
totaled $1.6 million with funding provided by
federal, state, local, and various other grants.
Operations and maintenance cost an estimated
$100,000 per year.96 Fees assessed to city
property owners based on the amount of
impervious surface area on their properties help
cover these costs. Each MVIC property owner
pays 40 percent of the stormwater fee to the city
and the remaining 60 percent to the
Redevelopment Authority of the City of
Milwaukee, which uses these funds to manage
Stormwater Park. This arrangement provides a
dedicated source of revenue for the park,
reducing the potential for future stormwater fee
increases to cover maintenance or
enhancements.97
Exhibit 29. For the first time in decades, people can
access the Menomonee River from the MVIC site.
E. BENEFITS
The MVIC project revitalized a vacant, blighted
area into a thriving industrial park with public
green space, including sports fields and a canoe
launch. More than 60 acres of new park and open
space provides public access to the Menomonee
River along a stretch of the river that had been
inaccessible for more than 50 years (Exhibit 29).
A pedestrian and bicycle bridge across the river
links the site to 7 miles of regional trails
connecting the site to greater Milwaukee.98 More
than 22,000 people use the park annually,
spanning all four seasons.99
Stormwater Park reduces pollution flowing to the
Menomonee River and controls 100-year flood
volumes from a 100-acre area.100 Its ability to
treat the entire development at levels exceeding
regulatory requirements is an attractive
incentive for businesses to locate there because
it eliminates the need for prospective developers
to construct individual on-lot stormwater
systems that would reduce the amount of
developable land.101 Clustering development and
designing shared stormwater facilities increased
the developable area by 10 to 12 percent over
95 Personal communication with David Misky, Assistant
Executive Director, Redevelopment Authority of the City of
Milwaukee, on Jan. 7, 2016.
96 Cost data provided by CH2M Hill.
97 Personal communication with David Misky op. at.
98 Landscape Architecture Foundation (LAF). "Menomonee
Valley Redevelopment and Community Park."
http://landscapeperformance.org/case-study-
briefs/menomonee-vallev-redevelopment-and-communitv-
parkff/overview. Accessed June 24, 2015.
99 Urban Ecology Center. Menomonee Valley Research and
Citizen Science 2014 Review. 2014. https://www.scribd.com
/fullscreen /271050135?access_kev=key-2qX62PoQbrVXTeogPQ
uH&allow_share=false&escape=false&show_recommendations
=false&view_mode=scroll.
100 LAF. "Menomonee Valley Redevelopment and Community
Park." op. cit.
101 Misky and Nemke op. cit.
37
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conventional practices such as detention ponds
for flood control.102
An analysis estimated that the site's aesthetic,
ecologic, and recreational value increased by
$120 million after redevelopment.103 A 140-acre
contaminated site was cleaned up, improving
public health and returning unproductive land to
productive use.104 Over 3,000 feet of riverbank
stabilization and more than 500 new native trees
improved the river's water quality, wildlife
habitat, and area aesthetics.105 An ongoing
citizen science monitoring program in
Stormwater Park, the adjacent Three Bridges
Park, and the Hank Aaron State Trail showed that
four bat species, 24 bird species, snakes, foxes,
coyotes, mink, and other mammals use the
area.106
Economic benefits have been substantial as well.
As of 2015, the MVIC has 10 firms with more than
1,400 employees.107 In addition, property values
at the site increased 1,400 percent between
2002 and 2009, adding more than $1 million per
year to city property tax revenues.108 As of 2015,
only 5.3 out of 60 developable acres remain.109
F. LESSONS LEARNED
• Incorporating community outreach early in
the design process was instrumental to the
project's success. The outreach attracted
volunteers from local schools, businesses,
and neighborhood associations who regularly
plant new trees and shrubs, remove invasive
species, and pick up trash.110 As a result, the
community has a sense of stewardship in
Stormwater Park and its green infrastructure
components.
• Early recognition of opportunities to
coordinate with nearby construction projects
can lead to sharing services and materials
that can save a lot of money. MVIC
developers reused 700,000 cubic yards of fill
and recycled concrete from a local highway
reconstruction project.
• Including public benefits in industrial
redevelopment projects can help generate
long-term community support. Stormwater
Exhibit 30. Trails through the park let visitors observe
Stormwater management in action.
Park provides a new access point to the river
and connects the area to the regional bike
and pedestrian trail system, creating an
industrial area that is an economic engine for
the community and an important public
amenity.
102 LAP. "Menomonee Valley Redevelopment and Community
Park." op. cit.
103 Brownfield Renewal. "Menomonee Valley Industrial
Center." http: / /www. brownf ield renewal. com /renewal -
award-pro1ect-environmentaLimpact-menomonee_valley
_industrial_center-8.html. Accessed Jun. 24, 2015.
104 LAP. "Menomonee Valley Redevelopment and Community
Park." op. cit.
105 Ibid.
106 Urban Ecology Center op. cit.
107 Daykin, Tom. "City to Study Expansion of Menomonee
Valley Industrial Center." Journal Sentinel. Feb. 19, 2015.
http://www.1sonline.com/business/citv-to-study-expansion-
of-menomonee-valley-industrial-center-b99448425z1-
292737391.html.
108 LAP. "Menomonee Valley Redevelopment and Community
Park." op. cit.
109 Memomonee Valley Partners, Inc. "Available Properties."
http://www.renewthevallev.Org/categories/11 -development
/documents/29-available-properties. Accessed Jul. 2, 2014.
110 NALGEP. "Spotlight on Milwaukee: Industrial Center and
Community Park is Model of Sustainable Redevelopment."
Mar. 19, 2014. http://www.nalgep.org/news/19/15/
Spotlight-on-Milwaukee-lndustrial-Center-and-Communitv-
Park-is-Model-of-Sustainable-Redevelopment.html.
38
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G. PROJECT TEAM
• Owner and developer: The Redevelopment
Authority of the City of Milwaukee
• Engineering and environmental
remediation: Milwaukee Transportation
Partners (CH2M Hill and HNTB)111
• Lead planner and landscape architect:
Wenk Associates112
Rouse and Bunster-Ossa op. at. 112 Ibid.
39
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VI11. UPTOWN
NORAAAL CIRCLE
NORMAL, ILLINOIS
An innovative roundabout calms
traffic and creates a new public
gathering space in a stormwater park, helping to revitalize a
central business district.
Project type: Transportation; public plaza
Green infrastructure Underground cistern, filtration bogs, and structural cell and conventional
practices: tree planters
Completion date: 2010
The Uptown Normal Circle is a $15.5 million
redevelopment project that includes an
innovative stormwater management system, new
streets, and renovated streetscapes for the core
of the six-block Uptown area. A new roundabout
calms traffic at a previously chaotic three-way
intersection while creating a new public
gathering place within a stormwater park. The
project's main goal was to catalyze revitalization
of the central business district while showcasing
sustainability practices. It manages stormwater
from nearly 3 acres of impervious cover in the
central business district and is a valued public
amenity that has attracted new private
investment, helped spur continued downtown
redevelopment, and received national
recognition.113
A. SITE CONTEXT
Normal is a town of just over 50,000 people in
central Illinois. It was laid out in 1865 at the
confluence of the Chicago and Alton Railroad and
the Illinois Central Railroad. The town population
has grown slowly but steadily, but Normal's town
center began to decline as early as the 1950s as
downtown businesses started closing.114 By the
late 1990s, Normal suffered from storefront
113 Among other awards, this project received EPA's National
Award for Smart Growth Achievement. See: EPA. 2077
National Award for Smart Growth Achievement Booklet.
https://www. epa.gov/smartgrowth 72011-national-award-
smart-growth-achievement-booklet.
114 Gorsche, Jennifer K. "Circular Logic Reshapes Downtown
Normal." The Architect's Newspaper. Aug. 16, 2010.
http://archpaper. com/news/articles. asp?id=4768#.Va5BikOw
Gh.
40
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vacancies, declining property values, and nearly
100-year-old public infrastructure in dire need of
updating.115
B. PLANNING AND
REGULATORY CONTEXT
In 1999, Normal embarked on an ambitious
redevelopment project to catalyze revitalization
in the town center and help reverse the
downward trajectory. The town developed the
Downtown Normal Redevelopment Plan116 after
community input from more than 70 public
meetings. In 2001, the town council adopted the
plan, which incorporates environmental
sustainability as a strategy to help boost the
economy. It included one of the first ordinances
in the country to require buildings over 7,500
square feet to meet green building standards,
plans for a multimodal transportation center that
links local and regional transit, and streetscape
improvements to create a more walkable town
center.117
The Uptown Normal Circle was a key
recommendation of the redevelopment plan. The
project focused on resolving long-standing design
problems arising from an awkward intersection
of three streets that divided the central business
district. Designers proposed a new traffic
roundabout to slow traffic, improve pedestrian
Exhibit 31. The Uptown Normal Circle sits at a formerly
chaotic three-way intersection.
safety, and use green infrastructure to manage
stormwater, while providing an interactive green
space for the community to enjoy.118
The circle was designed to convey a 10-year
storm event, meeting state and local standards
for stormwater management. The project was
not subject to any water quality treatment
standards, so all of the water quality
enhancement elements of the project were
voluntary.
C. DESIGN AND PERFORAAANCE
Green infrastructure is a key feature of the
circle, which captures, stores, cleans, and
recycles water from several streets surrounding
the circle. A 75,000-gallon underground cistern,
created from an abandoned storm sewer line,
provides storage space for stormwater runoff.
This recycled water helps irrigate the six-block
core of the central business district. The water
circulates by gravity through a series of terraced
115 Town of Normal. "History of Redevelopment." https://
www. normal.org/index.aspx?NID=832. Accessed Jul. 20,
2015.
116 The Normal Town Council voted to change the name of
"Downtown Normal" to "Uptown Normal" in 2006.
117 Town of Normal, "History of Redevelopment" op. at.
filtration bogs in the circle.119 From the bogs,
cleansed water flows first into a collection pool
and then into a secondary underground reservoir
where it is treated by ultraviolet light to destroy
microorganisms. From the secondary reservoir,
water is pumped through a shallow, stream-like
fountain that people can dip their feet in to cool
118 Gray, Rob. "Sustainability as Catalyst: Uptown Normal
Circle." APWA Reporter. Apr. 2011: 66-70. http://www.
apwa.net/Resources/Reporter/Articles/2011/47
Sustainabilitv-as-catalyst-Uptown-Normal-Circle.
119 Ibid.
41
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DETENTION O5TERN SUPPLY FROM STQRMWATER
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Exhibit 32. A cross section of the circle shows the flow of water through the system.
off and that creates sound to mask the nearby
traffic noise (Exhibit 32).120
The project also incorporates infiltration
planters and underground structural cells for
tree plantings in a ring around the circle and
along the nearby sidewalks that help prevent soil
compaction and retain absorptive capacity.
Although water quality treatment was not
required, the system is estimated to remove an
estimated 91 percent of total suspended solids,
79 percent of total phosphorus, and 64 percent
of total nitrogen from stormwater.121
D. COSTS AND FUNDING
The entire redevelopment for the circle and
surrounding streets, including utilities, roads,
streetscape improvements, and landscaping,
totaled approximately $15.5 million, with
stormwater costs of $1.3 million, about half of
which was for aesthetic features and half of
which was for functional components.122 The
town recognized early on that the downtown
redevelopment plan would have a greater chance
of implementation with a dedicated source of
local funding. New revenue sources dedicated
solely to the redevelopment effort included a
120 Town of Normal. The Uptown Normal Circle. Undated.
http://www.normal.org/DocumentCenter/View/4409.
121 Landscape Architecture Foundation (LAP). "Uptown
Normal Circle and Streetscape." http://landscape
sales tax, a hotel/motel tax, a food and
beverage tax, and establishment of a tax-
increment financing district that allowed future
increases in property taxes in the area to be
directed to area improvements.123 Other sources
of funding for the overall redevelopment plan
included municipal bonds and grants from the
Federal Transit Administration and the Illinois
Department of Commerce and Economic
Opportunity.124 A U.S. Department of
Transportation TIGER grant helped fund the
multimodal transportation center. In addition, in
performance.org/case-study-briefs/uptown-normal-circle-
and-streetscape. Accessed Jul. 20, 2015.
122 Cost data provided by the town of Normal.
123 Town of Normal, "History of Redevelopment" op. cit.
124 Gray op. cit.
42
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2006, the town enacted a stormwater utility fee
that generates about $1.8 million per year for
maintenance and construction of new
stormwater management practices.125
E. BENEFITS
The site captures 1.4 million gallons of
stormwater annually, reducing the burden on the
municipal stormwater system.126 More than 100
new trees sequester nearly 11,000 pounds of
carbon annually and reduce ambient
temperatures. Because of the use of structural
planting cells, the trees have an expected
lifespan triple that of conventionally planted
street trees.127
In addition to environmental benefits, the
project created a place where the community
gathers for special events and daily use. A/tare
people now walk and bike to the Uptown
District, and the project has attracted new
businesses and people. After completion of the
redevelopment plan, including the Uptown
Circle, reconstruction of Constitution Boulevard,
and construction of the transportation center,
private businesses invested $160 million in the
Uptown District, including the construction of a
Exhibit 33. The Uptown Normal Circle serves multiple
purposes in a small space previously used solely for traffic.
new hotel and conference center. Property
values went up 16 percent, and retail sales grew
46 percent.128 At least four organizations chose
to hold conferences in Normal that featured the
completed circle, bringing nearly $700,000 in
tourism dollars to the city.129
F. LESSONS LEARNED
• Environmental sustainability initiatives can
help generate economic development. The
Downtown Normal Redevelopment Plan's
focus on sustainability, including the Uptown
Normal Circle, has garnered nationwide
recognition that has helped attract
conferences and private investment.
• Identifying a locally generated funding source
for green infrastructure projects like Normal's
stormwater utility fee can help ensure both
their implementation and long-term success.
While federal and state funds can help
significantly with capital costs, long-term
maintenance generally is a local
responsibility. Maintenance is particularly
125 Aldrich, Wayne. "Storm Water Utility Fees." WTVPAt
Issue. Episode #2728. May 14, 2015. http: //www.wtvp.org/
programming/ai/2-2728.asp.
126 LAP. "Uptown Normal Circle and Streetscape." op. at.
127 Ibid.
Exhibit 34. Stormwater features in the Uptown Normal
Circle manage runoff while creating a beautiful park for
the public to enjoy.
128 Smart Growth America and National Complete Streets
Coalition. Safer Streets, Stronger Economies: Complete
Streets Project Outcomes from Across the Country. 2015.
http://www.smartgrowthamerica.org/research/safer-
streets-stronger-economies.
129 LAP. "Uptown Normal Circle and Streetscape." op. cit.
43
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important for green infrastructure projects
because they are so visible to the community.
• Community leaders' support can be critical to
overcome public skepticism about the value
of spending public dollars on aesthetic
improvements. Educating the public about the
multiple environmental, economic, and social
benefits was important to generate
community support in Normal for new types of
infrastructure investments.
G. PROJECT TEAM
• Owner and developer: Town of Normal,
Illinois
• Engineers: Clark Dietz Incorporated
(roadway design) and Farnsworth Group
(underground infrastructure design)
• Landscape architect: Hoerr Schaudt
Landscape Architects
• Master planners: Farr Associates
Exhibit 35. The Uptown Normal Circle attracts residents and
visitors to the business core by providing a gathering place.
44
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IX. THE METRO
GREEN LINE
ST. PAUL, MINNESOTA
Green infrastructure along a
new light rail corridor provides stormwater management for
the largest public works project in Minnesota history.
Project type: Transportation; brownfield redevelopment
Green infrastructure Integrated tree trench system with structural soil, stormwater planters, rain
practices: gardens, and infiltration trenches
Completion date: 2012; rail service began in 2014
The Metro Green Line (formerly the Central
Corridor Light Rail Transit project) covers 11
miles, connecting the major downtown areas of
the Minnesota state capital in St. Paul with
Minneapolis. This case study focuses on the 7.5-
mile section of the project that is in St. Paul and
under the jurisdiction of the Capitol Region
Watershed District (CRWD). CRWD regulations
required the Green Line project to include
stormwater quality improvements, preferably
infiltration, wherever feasible. However, an
extensive system of underground utilities
provided little space. To address this challenge,
the Metropolitan Council, the regional planning
agency serving St. Paul and Minneapolis' seven-
county metropolitan area, developed an
innovative stormwater management system that
includes an integrated tree trench system. In
addition, CRWD and the city of St. Paul
augmented stormwater management in the
corridor with stormwater planters, rain gardens,
and infiltration trenches on side streets. Green
infrastructure was a cost-effective way to
comply with stormwater regulations while
providing additional benefits that helped gain
public support from the surrounding community
for the project. A new canopy of more than
1,250 trees along the heavily developed route
will provide shade, beautify the area, and
improve air and water quality.
A. SITE CONTEXT
The city of St. Paul lies mostly on the north bank
of the Mississippi River adjacent to Minneapolis.
Most of the light rail route follows University
Avenue, one of the oldest streets in the
45
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metropolitan area. It was served by streetcars
from 1890 until 1954 and developed with a mix
of manufacturing, retail, hospitals, offices,
entertainment venues, and housing. 13° The
corridor is racially and ethnically diverse and has
higher levels of poverty than the surrounding
metropolitan region.131
Before construction, the 120-foot-wide right-of-
way for the rail line was mostly impervious,
including a four-lane road from which all
stormwater runoff flowed untreated directly to
the Mississippi River through numerous outfalls,
carrying sediment and pollution. The relatively
narrow project space, the city's desire to
accommodate compact development near rail
stations, and a prohibition on infiltration into the
road subbase limited the types of green
infrastructure that would be suitable.
Contaminated soils and shallow groundwater
limited green infrastructure to approximately
50 percent of the St. Paul segment of the
project.
B. PLANNING AND REGULATORY CONTEXT
In 2003, CRWD began developing stormwater
management guidelines for development and
redevelopment in the area. However, two years
after issuing the guidelines, the district found
that many developers were not installing any
stormwater management controls, so CRWD
decided to develop formal regulatory rules.132
In 2006, CRWD issued water quality and
stormwater management rules for projects
disturbing more than 1 acre of land. The rules
require reducing pollution flowing to lakes,
wetlands, and the Mississippi River by meeting
standards for runoff rate, volume reduction, and
water quality. A volume equal to 1 inch of
rainfall from impervious surfaces on the site
must be retained on-site, and best management
practices must remove 90 percent of total
suspended solids from the runoff generated by a
2.5-inch rainfall event.133
During the rulemaking process, commenters were
concerned with the cost of compliance for major
public transportation projects, particularly linear
projects that generally have space constraints,
extensive utilities, and a high percentage of
impervious cover. These concerns led to a cost
cap for linear projects that limits costs for
complying with stormwater regulations to
$30,000 per acre of new or reconstructed
impervious surface, an amount that is set
annually by the CRWD Board.134
C. DESIGN AND PERFORAAANCE
CWRD and its partners convened a stormwater
design workshop in June 2009 with more than 50
participants. The workshop led to development
of conceptual plans for stormwater management
along the Green Line that would meet the CRWD
stormwater standards cost-effectively while
achieving other community goals such as cleaner
air, more green space, and improved aesthetics
along the corridor.135
The centerpiece of the design is an integrated
tree trench system that accommodates the site's
limitations. It can infiltrate runoff from the
roads and rail line while safely supporting traffic
130 Isaacs, Aaron. "Rail Returns to the Central Corridor."
MetroTransit blog. Jun. 11, 2014. http://www.metrotransit
.org/rail-returns-to-the-central-corridor. Accessed Jan. 15,
2015.
131 PolicyLink, TakeAction Minnesota, and ISAIAH. Healthy
Corridor for All: A Community Health Impact Assessment of
Transit-Oriented Development Policy in Saint Paul,
Minnesota. 2011. http://isaiahmn.org/2012/01/healthy-
corridor-for-all.
132 CRWD. "Watershed Rules." http://www.capitolregionwd.
org/permits/watershed-rules. Accessed Jan. 15, 2015.
133 Ibid.
134 Ibid.
135 Eleria, Anna, and Forrest Kelley. "Green Infrastructure for
the Central Corridor Light Rail Transit Project." 2013
International Low Impact Development Symposium. Aug. 18-
21, 2013. http://assets.conferencespot.org/fileserver/file/
34648/filename/a621_1 .pdf.
46
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loads and protecting tree roots. A PVC barrier
keeps infiltrated water away from the road
subbase. To avoid existing utilities and limit the
impacts on the existing road, the tree trench
system is located under curbing, sidewalks, and
boulevards along 5.2 miles of University Avenue
where the soil is suitable for infiltration (Exhibit
36).
The system includes permeable pavers and
"structural soil," which is gravel with a
specialized soil coating similar in size and
function to conventional load-bearing subbase
materials. It can support heavy loads of foot and
vehicle traffic along the corridor, and tree roots
can grow through it. Rainfall on the sidewalks
infiltrates through permeable pavers and
structural soils, supplying water and air to the
tree roots, while catch basins and a perforated
pipe direct runoff from the road to infiltration
chambers.
The system supports 1,250 new trees along the
corridor and reduces runoff to the maximum
extent practicable in the limited available space
in compliance with the CRWD requirements.
CRWD and the city of St. Paul installed additional
green infrastructure practices along the corridor
and adjacent streets, including stormwater
planters, rain gardens, and infiltration
trenches.136 Maintenance of the green
infrastructure practices on side streets with high
pedestrian traffic involves biweekly trash and
debris removal and annual weeding and plant
replacement.137
Pre-construction estimates for the performance
of the integrated tree trench system and other
green infrastructure practices were that they
would reduce stormwater volume by 50 percent,
phosphorus loading by 85 pounds, and sediment
loading by 20,000 pounds per year, helping to
improve water quality in the Mississippi River.138
Testing after construction showed that the tree
trench system is exceeding its performance
targets.139 Monitoring has been continuing since
2013, and CWRD plans to issue a report on
performance and pollutant removal effectiveness
in 2016.140 Although the project does not strictly
meet volume reduction standards, it complies
with the stormwater regulations because it
exceeded the cost cap set for linear projects.
Exhibit 36. A tree trench system along University Avenue
allows room for roots to grow in a highly trafficked area.
Additional features of the light rail project
include a pedestrian mall, improved sidewalks
and crosswalks, bike racks, planters, benches,
permeable pavers, and LED lighting. These
features work together with the green
infrastructure to make a pleasant and safe
environment for people walking and biking to the
light rail stations.
136 Minnesota Pollution Control Agency. "Case Studies for Tree
Trenches and Tree Boxes." http://stormwater.pca.state.mn.
us/index. php/Case_studies_for_tree_trenches_and_tree_
boxes. Accessed Jan. 16, 2015.
137 Ibid.
138 CRWD. 2014 MAWD Project & Program of the Year. 2014.
http://www.capitolregionwd.org/wp-content/uploads/2014
/10/Capitol-Region -pro1ect-of-the-year-final-nomination.pdf.
139 Eleria and Kelley op. at.
140 persona[ communication with Mark Doneux, Administrator,
CRWD, on Nov. 25, 2015.
47
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D. COSTS AND FUNDING
The total project cost for the Green Line was
nearly $1 billion, the largest completed public
works project in Minnesota history.141 Multiple
sources provided financial support (Exhibit 37).
Stormwater costs for the Green Line totaled
$5,114,865, or 0.5 percent of the total project
costs. Funding for the stormwater costs came
from a Minnesota Clean Water Legacy Fund grant
for $665,000, and contributions from CWRD, the
Metropolitan Council, and the city of St. Paul.142
FUNDING SOURCE PERCENTAGE
Federal Government
Counties Transit Improvement Board
Minnesota state
Ramsey County
Hennepin County
Metropolitan Council
City of St. Paul and Central Corridor
Funders Collaborative
50
30
9
7
3
1
<1
Exhibit 37. Total project funding.
Source: Metropolitan Council. "Project Funding." http://www.metro
council.org/Transportation/Proiects/Current-Proiects/Central-
Corridor/Grants-Funding-(CCLRT).aspx. Accessed Jan. 15, 2015.
E. BENEFITS
The green infrastructure practices developed for
the Green Line allowed the city to meet its goals
of improving regional transportation options,
facilitating compact redevelopment along the
new transit corridor, and improving water quality
in the Mississippi River. The Green Line is
exceeding ridership expectations, with 45,644
daily riders as of September 2014, more than
originally predicted to occur by 2030.143
A new tree canopy in this densely developed
area with limited green space helps capture
stormwater, improve air quality, reduce
temperatures during hot weather, and beautify
the neighborhood. Because of the trench system,
the 1,250 new trees are much more likely to
survive in the harsh urban environment and will
require less irrigation than other street trees,
saving maintenance costs. Because melting snow
will infiltrate rather than refreezing, the
permeable sidewalks will require less salt in the
winter to maintain a safe walking surface, saving
money and reducing salt going to the Mississippi
River. Interpretive signage along the Green Line
in English, Spanish, and Hmong helps educate rail
users about the need for stormwater pollution
controls and how the green infrastructure
Exhibit 38. Signs help passersby understand the
importance and function of rain gardens and other green
infrastructure.
141 Metropolitan Council. "Metro Green Line Opens On Time
and On Budget." Jun. 14, 2104. http://www.metrocouncil
.org/News-Events/Transportation/News-Articles/MET RO-
Green-Line-opens-on-time-and-on-budget.aspx.
142 Buranen, Margaret. "Green Infrastructure Makes Sen$e in
the Twin Cities." Stormwater. Jan./Feb. 2013. pp. 8-11.
http: //digital. stormh20.com/publication/index.php?p=11
&i=138017&ver=swf&pp=2&zoom=0.
143 Personal communication with Anna Eleria, CRWD, on Nov.
25,2015.
48
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installations improve water quality (Exhibit
38).144
Construction of the Green Line spurred more
than $2.5 billion in private redevelopment along
the corridor even before starting operation in
2014 (Exhibit 39).145 In spite of disruptions due to
construction of the Green Line, there was a net
gain of 13 businesses directly on the line during
the construction period between February 2011
and June 2014. In addition, 4,459 market-rate
and 2,375 new or preserved long-term affordable
housing units were created during this period.146
Exhibit 39. New businesses along the Green Line can
benefit from the increased foot traffic it brings to
neighborhoods.
F. LESSONS LEARNED
• Implementing green infrastructure in a major
public project can encourage wider use of
green infrastructure by demonstrating its
benefits. The city of St. Paul and CRWD
installed additional green infrastructure on
adjacent streets along the Green Line
corridor, and the entire area serves as a
demonstration project for other
developments in the city.
• Screening for soil contamination that could
limit the ability to infiltrate stormwater
should occur before project design to
identify areas suitable for green
infrastructure. Designers had to reconfigure
the project after initial planning, reducing
the expected benefits.
• Green infrastructure can be feasible on
highly constrained sites without space for
conventional stormwater management. The
Green Line could not have accommodated
conventional stormwater treatment in the
narrow right of way available due to existing
infrastructure.
G. PROJECT TEAM
• Owner and developer: The Metropolitan
Council
Engineers: AECOM, Kimley-Horn and
Associates, Inc. and HZ United147
144 CRWD. "Green Line Green Infrastructure Practices - Water
Quality." http://www.capitolregionwd.org/our-work/
watershed-planning/cclrt_wq. Accessed Jan. 16, 2015.
145 Metropolitan Council. "Metro Green Line Helps Attract at
Least $2.5 Billion in Development." May 14, 2014.
http://www.metrocouncil.org/News-Events/Transportation/
News-Articles/Metro-Green-Line-helps-attract-at-least-$2-5-
billi.aspx. Accessed Jan. 16, 2015.
146 Business Resources Collaborative. Healthy Local
Businesses, Healthy Communities. 2015. http: //www.funder
scollaborative.org/sites/default/files/BRC_0315-1_FinaL
Report_10.pdf.
147 Minnesota Pollution Control Agency op. at.
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X. SANTA FE
RAILYARD PARK
AND PLAZA
SANTA FE, NEW MEXICO
An abandoned raiiyard is transformed into a flourishing
community activity center, including a 10-acre park that helps
reduce stormwater runoff.
p . . Commercial development; public park and plaza; historic preservation;
brownfield redevelopment
Green infrastructure Comprehensive site planning, water harvesting (cistern and water tower,
practices: swales, and two stormwater detention areas)
Completion date: 2008
The Santa Fe Raiiyard Park and Plaza project
converted an abandoned raiiyard into a
flourishing community activity center that
incorporates green infrastructure for water
conservation. The design for the site, chosen
through an international design competition,
incorporated significant community input. It
integrates the site's historic features and open
space into the fabric of downtown and adjacent
neighborhoods.
The project includes a 10-acre park, a 1-acre
plaza, and a 1.5-acre pedestrian walkway, which
are protected under a permanent conservation
easement. A water harvesting system can store
110,000 gallons of stormwater collected from
impervious surfaces on the property. The project
also included the restoration of the Acequia
Madre, a historic irrigation canal running through
the site. Water is a major aspect of this
redevelopment because Santa Fe is in an arid,
high-desert climate, and water conservation is a
major concern.
A. SITE CONTEXT
In downtown Santa Fe, the site of the Raiiyard
Park and Plaza was historically used for
agriculture by Native Americans and Spanish
settlers. Along the site runs the Acequia Madre,
50
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one of the oldest irrigation canals in the United
States dating back to the 1600s.148
In the 1880s, the area became the site of a
railyard, with surrounding neighborhoods created
to house workers and their families. By the
1940s, the area became a center of community
life with gardens, swimming, and ice skating.149
However, after the railroad suspended passenger
service following World War II, the railyard and
surrounding neighborhoods began to decline. By
1987, the area was declared blighted, and the
city launched a master-planning process to
redevelop it.150 Due to its industrial past, the site
was contaminated with lead and other metals,
petroleum, and petroleum products, impeding
redevelopment.151
Exhibit 40. The Santa Fe Railyard Park and Plaza is a
center of activity for the surrounding neighborhoods.
B. PLANNING AND REGULATORY CONTEXT
The planning process took years, as citizen
activists strongly pushed to create a pedestrian-
oriented area with public open space and local
businesses, reestablish rail service, and preserve
the character of surrounding neighborhoods. In
1995, the Trust for Public Land and the city
worked together to buy the Santa Fe Railyard
and redevelop the area, placing 13 of the site's
50 acres under a permanent conservation
easement.152
Ultimately, more than 6,000 residents provided
input into the railyard's redevelopment. In 2002,
the city council approved the Railyard Master
Plan and organized the Santa Fe Railyard
Community Corporation to oversee mixed-use
development for 37 acres of the site. Meanwhile,
the Trust for Public Land conducted an
international design competition for the
railyard's public spaces. It called for a new park
and plaza integrated with the social life of the
city through the protection and enhancement of
historic areas.153
Environmental contamination at the site was
cleaned up by 2006 with assistance from U.S.
Environmental Protection Agency brownfields
assessment grants and the New Mexico
Environment Department's Voluntary Cleanup
Program, setting the stage for development to
begin.154
The city's stormwater management standards
required that the stormwater runoff peak flow
rate discharged from the site not exceed pre-
development conditions for the 100-year, 24-
hour storm event. The city's landscape and site
design standard required the use of water
harvesting and encouraged developing and using
148 Crawford, Stanley. "A Central Park for Santa Fe." Land +
People. Spring/Summer 2009. https://www.tpl.org/magazine
/central-park-santa-fe%C2%97landpeople.
149 The Santa Fe Railyard Community Corporation. "Railyard
History." http://www.railvardsantafe.com/history. Accessed
Aug. 11, 2015.
150 Shibley, Robert, Brandy H.M. Brooks, Jay Farbstein, and
Richard Wener. Partnering Strategies for the Urban Edge:
2011 Rudy Bruner Award for Urban Excellence. 2011.
http://www.brunerfoundation.org/rba/pdfs/2011/2011Book.
Edf.
151 New Mexico Environment Department. "Brownfields
Success Stories." https://www.env.nm.gov/gwb/NMED-
GWQB-BrownfieldsSuccessStories.htm. Accessed Aug. 11,
2015.
152 Shibley, Brooks, Farbstein, and Wener op. cit.
153 Shibley, Brooks, Farbstein, and Wener op. cit.
154 EPA. Old Santa Fe Railyard: Back on Track to
Revitalization. 2008. nepis.epa.gov/Exe/ZyPURL.cgi?
Dockey=P 1007CTE.TXT.
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sources of landscape irrigation water other than
potable water.155
Designers faced several constraints in designing
the stormwater management system for the site.
Water rights are a key consideration in this arid
region. Due to New Mexico's commitments under
the Rio Grande Compact,156 the Office of the
State Engineer prohibits passive water
harvesting—techniques that would detain water
so that it could slowly infiltrate into the soil.
Regulations allowed for active water harvesting-
collection in a storage container for later use-
but only for runoff within the 50-acre site and
not from surrounding streets. In addition, the
city did not allow designers to construct a
decentralized wastewater treatment plant from
which treated effluent could be used for
irrigation.157
C. DESIGN AND PERFORAAANCE
Runoff from approximately 3.7 acres of railyard
buildings and impervious surfaces is collected in
five 15,000-gallon underground storage tanks and
a 35,000-gallon water tower for a total of
110,000 gallons of storage capacity that supplies
irrigation for the park. The tower is not only a
storage facility but also a landmark that
contributes to the area's character.158 Swales
and stormwater detention facilities also help
reduce runoff rates, slowing erosion. However,
runoff volume is not reduced due to regulations
prohibiting passive water harvesting that
required water collected by these practices to be
piped into the drainage system rather than
infiltrated.
Extensive native plantings were incorporated
into the landscape, which includes a shady
riparian area, a dry gulch that fills seasonally
with rain, ornamental gardens adapted for dry
conditions, and bird and butterfly gardens
(Exhibit 41). In addition, the area's historical
agriculture is represented through community
gardens, orchards, and historic Pueblo gardens
designed for arid conditions.159 The Acequia
Madre Association granted permission for a
diversion channel to provide additional irrigation
water for the community gardens in the park,
Exhibit 41. The Railyard Park incorporates extensive
native plantings and naturalistic landscaping.
much as the Acequia Madre has been supplying
water to the area for 400 years. The irrigation
system, signage, and outdoor classrooms at the
community gardens help the public understand
the link between historical agriculture practices
and the need for water conservation in a region
with limited water resources.160
The water harvesting system has flow sensors
that track the amount of rainwater collected and
used and supplemental city water needed. The
public can view monthly, annual, and
accumulated historical data.161
155 City of Santa Fe. "Article 14-8: Development and Design
Standards." 2001. http://clerkshq.com/Content/Santafe-
nm/books/landdevelopment/sfld_a8.htm.
156 The Rio Grande Compact is a 1938 agreement among
Colorado, New Mexico, and Texas that apportions the waters
of the Rio Grande Basin.
157 Personal communication with Frederic Schwartz, Frederic
Schwartz Architects, on Apr. 19, 2011.
158 Crawford op. cit.
159 Railyard Stewards. "Horticulture in the Park."
http://www.railvardpark.org/park-plaza/horticulture-in-the-
park. Accessed Aug. 11, 2015.
160 Schwartz op. cit.
161 Ibid.
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D. COSTS AND FUNDING
The railyard redevelopment project cost $137
million in total, including an estimated
$70 million in private investment as of 2011. The
cost of the park, plaza, and walking path was
$13 million, including $400,000 for planning,
$1.1 million for design and engineering,
$10.5 million for construction, and $1.5 million
for administrative costs.162 Stormwater costs
amounted to about $2 million, or 15 percent of
total project costs.163 The Trust for Public Land
raised $13 million from:
• State legislative appropriations
($3.1 million).
• Federal transportation funds ($2.4 million).
• City capital improvement bonds
($1.3 million).
• City and county gross receipts taxes
($600,000).
• Santa Fe Southern Railway ($2.3 million).
• Other private donors ($3.1 million).164
Volunteers from the Trust for Public Land formed
a membership group, the Railyard Stewards, to
help provide maintenance, program events, and
advocate for the park. The Railyard Stewards
work with the city of Santa Fe to encourage
residents to visit the park and plaza.165
E. BENEFITS
The Railyard Park and Plaza redevelopment
project restored a former brownfield to the
vibrant downtown community center it once
was. The Railyard Plaza hosts performances and
special events, while also providing regular space
for food vendors and a farmers market featuring
local growers and artisans. About 20 percent of
the project site has been protected through a
conservation easement as public open space. The
Railyard Park includes an informal outdoor
performance space, a children's play area, picnic
areas, community gardens, and a walking and
biking trail linked to a citywide trail. The New
Mexico RailRunner Express commuter rail service
stops at the historic Santa Fe Depot, building on
the location's long history of train travel.166
The city's investment in the Railyard
redevelopment project led to millions of dollars
in private investment, including restaurants,
shops, and a cinema.167 More than 90 percent of
tenants in the Railyard are local businesses and
nonprofit organizations.
Exhibit 42. The farmers market at the Railyard Plaza is a
popular gathering place.
An innovative water harvesting system, which
works within the water rights restrictions
common to arid regions, uses stormwater runoff
to irrigate more than 300 new trees and several
thousand drought-resistant and native plants.
162 Crawford op. at.
163 persona[ communication with Suby Bowden, Suby Bowden
+ Associates, on Apr. 28, 2011.
164 Crawford op. at.
165 Railyard Stewards. "The Railyard Stewards."
http://www.railyardpark.org. Accessed Aug. 11, 2015.
166 Crawford op. at.
167 KRQE News. "Santa Fe Railyard is getting two new
attractions." May 22, 2015. http://krqe.com/2015/05/22/
santa-fe-railyard-adding-two-new-attractions.
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F. LESSONS LEARNED
• Green infrastructure can help achieve water
conservation goals in arid climates by storing
stormwater for irrigation. Even areas subject
to water rights laws can incorporate green
infrastructure into development projects.
• Maximizing developable area on a site is not
always conducive to meeting a community's
goals for that site. The Santa Fe Railyard
project reduced the development density on
the site in exchange for preserving historic
places tied to the city's identity and creating
a large open space that serves city residents
and helps protect the environment. In
return, the developers garnered more
support for the project and sparked
community pride in the project.
Exhibit 43. The Santa Fe Railyard builds on the city's
unique assets to create a space that residents and
visitors love.
G. PROJECT TEAM
• Owner: The City of Santa Fe
• Developer: The Trust for Public Land
• Engineering: URS
• Architect: Fredric Schwartz
• Landscape architect: Ken Smith
• Landscape artist: Mary Miss
• Landscape design: Edith Katz
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XL STAPLETON
GREENWAY PARK
DENVER, COLORADO
When an airport is redeveloped
into a mixed-use community,
30 percent of the land is set aside for open space used for
recreation and stormwater management.
Project type: Mixed-use development; public park
Green infrastructure practices: Vegetated swales and constructed wetland
Completion date: 2002
The Stapleton Airport redevelopment converted
an obsolete airport just 6 miles from downtown
Denver into a mixed-use community with single-
and multifamily homes, businesses, restaurants,
office space, and schools, setting aside
30 percent of the area for open space. Its public
parks and greenways are a key selling point and a
cherished amenity for those who live in, work in,
or visit Stapleton. The developer integrated
green infrastructure into the parks and
landscape, creating centralized facilities that
simultaneously meet water quality, flood
control, and open space requirements.
A. SITE CONTEXT
In 1989, city leaders in Denver, Colorado,
decided to build a new airport. By abandoning
Stapleton International Airport, they created a
4,700-acre redevelopment opportunity in an
already-developed area 6 miles from
downtown.168
Westerly Creek once flowed through the site, but
construction of the airport in 1929 enclosed the
168 Carder, Carol. "New Life at an Old Airport." Progressive
Engineer. 2011. http: / /www. progressiveengineer. com /
features/new_life_old_airport.htm.
169 Ibid.
creek in two underground pipes. The Westerly
Creek watershed covers 18.5 square miles of
mostly developed land, leaving the area subject
to seasonal flooding when stormwater flows
exceed the capacity of the piping system.169 In
addition, stormwater runoff from the site caused
both surface and groundwater contamination. 17°
170 City and County of Denver, Stapleton Redevelopment
Foundation, and Citizens Advisory Board. Stapleton
Development Plan. 1995. http://stapletonfoundation.com/
wp-content/uploads/2015/05/GreenBook1995_ForWeb
Viewing.pdf.
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B. PLANNING AND REGULATORY PROCESS
The city and county of Denver, Denver
International Airport, and citizen advisory groups
began planning for redevelopment before the
airport closed. A two-year community planning
process developed a concept plan for reuse of
the airport site and ultimately a master
development plan published in 1995. The plan
was guided by three overarching goals:
• Create a regional job center that can
contribute to the city's long-term economic
health.
• Demonstrate the benefits of reducing
consumption of natural resources and
impacts on the natural environment.
• Provide access to social, cultural, and
economic opportunities for the entire
community.171
The plan called for a walkable, vibrant
community with buildings compactly spaced on
small lots to allow for large, contiguous areas of
public green space. Designers met open space,
stormwater management, and flood control
Exhibit 44. The Stapleton Airport redevelopment site
encompasses 4,700 acres. The yellow asterisk marks the
Greenway Park.
requirements by incorporating green
infrastructure throughout the site.
C. DESIGN AND PERFORAAANCE
The stormwater treatment system was designed
before 2004 design regulations set by the Urban
Drainage and Flood Control District in Denver
went into effect. However, the system meets the
2004 requirements for water quality and flood
control.172 Design standards for the system
include:
• Capture and treatment of the 80th percentile
runoff event or 0.6 inches of rain.
• A 40-hour controlled drain time in detention
basins.
171 City and County of Denver, Stapleton Redevelopment
Foundation, and Citizens Advisory Board op. at.
172 Denver Urban Drainage and Flood Control District. Urban
Storm Drainage Criteria Manual Volume 3 - Best Management
• A runoff flow rate that matches pre- and
post-development peak flows for the 2-year
and 100-year storm events.
This case study focuses on the Stapleton
Greenway Park between 25th Drive and East 26th
Avenue, the community's first of several open
green spaces that provide stormwater
management for the entire development.
Greenway Park's green infrastructure practices
manage runoff from a 180-acre sub-watershed of
Westerly Creek that is 53 percent impervious.173
A conventional gutter and inlet collection system
captures runoff from this area and conveys it to
outfalls in Greenway Park. Sediment forebays at
Practices. 2010. http://www.semswa.org/uploads/FileLinks/
aOb9436a763f4470a648b3fca2de80b3/USDCM_Volume_3.pdf.
173 Personal communication with Dennis Arbogast, URS
Corporation, on May 19, 2011.
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each of the outfalls provide pretreatment.
Stormwater flows from the forebays into
vegetated swales that naturally convey the
stormwater through a constructed wetland
channel into an extended dry detention basin.
The detention basin controls peak flow rates for
the 100-year storm and provides controlled
release to Westerly Creek through an outfall pipe
that was originally part of the airport
infrastructure.
This system provides flood control and can
remove pollutants (including phosphorus,
nitrogen, pathogens, and total suspended solids)
from a large contributing drainage area without
infringing on existing water rights.174
This community facility reduced the amount of
land required for stormwater management while
making the park more attractive and providing
diverse soil and water conditions that can
i
Exhibit 45. Homes in Stapleton have views of the
stormwater facility and park.
support a wide variety of vegetation, improving
wildlife habitat. Other design strategies included
reducing the amount of pavement and
disconnecting impervious areas from the
stormwater management system.
D. COSTS AND FUNDING
Developer Forest City Stapleton, Inc. created
the Park Creek Metropolitan District (PCMD) to
design and construct Stapleton's infrastructure.
PCMD gets funding from several sources:175
• Forest City pays PCMD a one-time $15,000
system development fee per acre.
• The city established a tax-increment
financing district in Stapleton. Tax
payments to the city taxing authorities are
frozen at 2000 levels, while taxes above
that base (due to rising property values)
fund regional infrastructure, including
parks and stormwater facilities.176
• The Westerly Creek Metro District levies
taxes for infrastructure construction and
maintenance.
• The PMCD has municipal bonding capacity
and therefore has access to bond proceeds.
• Forest City provides loans to PCMD when
necessary to continue the pace of
infrastructure development.
The cost of installing the stormwater
management system at Greenway Park to serve
the 180-acre watershed totaled $420,000,
including grading, outlet structures, forebays,
and irrigated landscaping for the constructed
stormwater wetland.177 PCMD is responsible for
maintenance, which costs approximately
$1,500 per year for routine activities such as
inspection and removal of trash and debris at
outlet control structures. In addition, annual
sediment removal costs approximately $2,000.
174 Colorado requires the evaporative losses from a
constructed permanent pool to be replaced by a similar
quantity of non-surface water entitlement or water right.
175 Roberts, Carol. "From Runways to Residences—How
Stapleton is Developed." The Front Porch. Jan. 2014.
http://fpstapleton.wpengine.netdna-cdn.com/wp-content
/uploads/2014/02/How-Stapleton-is-Developed.pdf.
176 Roberts, Carol. "How Stapleton Taxes Finance
Infrastructure." The Front Porch. Feb. 1. 2014.
http://frontporchstapleton.com/article/blighted-land-6-
billion-development-25-vears-stapleton-taxes-pay.
177 Arbogast op. cit.
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E. BENEFITS
Organization of the community around the
greenways and parks has helped make
Stapleton a very desirable area to live and
work. The president and chief operating officer
of Forest City Stapleton credits the emphasis
on parks and community open space with
helping to make Stapleton one of the best-
selling master-planned communities in the
United States.178
The vegetated swales and constructed
stormwater wetland are seamlessly integrated
into the park, which includes a playground,
boulder-climbing area, skate park, picnic areas,
and tennis courts.179 In addition to enhancing
the open space, the stormwater features
create a variety of conditions that support a
wide array of native vegetation important for
wildlife habitat. The greenway corridors,
including Greenway Park, attract small fish,
frogs, whitetail deer, snowy egrets, golden
eagles, killdeer, and red tail hawks.
Instead of directing stormwater directly to area
waterways through underground pipes, the
vegetated swales and constructed wetland
filter out nutrients and sediment, improving
Exhibit 46. Walking and biking paths allow residents to
use the open space that functions as a centralized
stormwater management facility.
water quality. They also control peak flow
rates, reducing erosion in receiving streams. By
providing undeveloped flood plain areas with
storage for 100-year flood events, the project
alleviated previous flooding issues resulting
from the site's limited storm sewer capacity
and broad and shallow flood plain. During a
major storm in 2011, the stormwater system
functioned as designed, flooding the Westerly
Creek channel while keeping developed areas
in the community dry.180
F. LESSONS LEARNED
• Green infrastructure is a viable option for
water quality treatment even in areas where
water rights preclude certain practices. The
vegetated swales and constructed wetland in
this case satisfied water rights requirements
not to retain, reuse, or store runoff.
• Centralized stormwater management
practices can create valuable community
amenities while maximizing developable
land. The centralized facilities in Stapleton
178 Forest City Stapleton, Inc. "Stapleton Denver Named
Number One Best Selling Master Planned Community in
Colorado, Sixth in Nation." Press release. Jan. 27, 2015.
http://www.stapletondenver.com/wp-content/uploads/
2015/01 /StapletonAwardRelease-2015.pdf.
are integrated into an extensive park system
that provides multiple community benefits,
creating value for the developer and
residents.
• Having a community-driven plan in place
even before soliciting developers for a large,
complex infill project can reduce developers'
risk by simplifying the approval process, help
generate interest from prospective buyers,
and ultimately facilitate implementation of
the community's vision. The 1995 Stapleton
179 Chroma Design. "Stapleton Greenway Park."
http://www.chromadesigninc.com/pro1ects/greenway-
l.htm. Accessed Aug. 20, 2015.
180 Roberts, Carol. "July 7, 2011-Why Stapleton Didn't
Flood." The Front Porch. Oct. 29, 2013. http://frontporch
stapleton.com/article/1uly-7-2011 -why-stapleton-didnt-
flood-2.
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Development Plan has guided the
community's development for 20 years,
creating certainty for all parties.
Large, complex infill projects can require
novel infrastructure financing tools.
Stapleton's developer pieced together a
combination of methods to get the job done,
including tax-increment financing, special
assessments, developer fees, and municipal
bonds.
G. PROJECT TEAM
• Master developer: Forest City Stapleton,
Inc.
• Master planner: Calthorpe Associates
• Program manager/engineer: URS
Corporation
• Civil engineer: Matrix Design Group, Inc.
• Water resources planning and design:
Matrix Design Group, Inc.
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XII. MINT PLAZA
SAN FRANCISCO, CALIFORNIA
A deteriorating alley becomes a
new public plaza that serves the
entire community, promotes
economic development, and
infiltrates stormwater.
Project type: Public plaza
Green infrastructure
practices:
Completion date: 2007
Rain gardens, infiltration chambers, and structural tree planters
The Mint Plaza redevelopment project
transformed a degraded alley in San Francisco
into an attractive public plaza with landscape
design elements that help manage stormwater.
Rain gardens, infiltration basins, and structural
tree planters that infiltrate stormwater keep
500,000 gallons of stormwater out of the city's
combined sewer system annually. The nationally
recognized181 Mint Plaza provides the community
with outdoor recreation space surrounded by
restaurants and shops with offices and residences
above. The plaza is frequently used for
community events such as farmers markets and
outdoor concerts.
The Mint Plaza project was the first of its kind in
San Francisco. It involved the closing of a public
street by a private developer to create a new
public space. The stormwater management
system employed at the site is now a prototype
for how to integrate green infrastructure into
highly urban sites across the city.
A. SITE CONTEXT
Mint Plaza is in San Francisco's Mid-Market
neighborhood on 5th Street next to the historic
U.S. Mint building (under renovation to become
an event space). The Mid-Market neighborhood
lies between the downtown commercial core to
the east and Civic Center, an area containing
181 Among other awards, this project received EPA's National
Award for Smart Growth Achievement. See: EPA. 2070
National Award for Smart Growth Achievement Booklet.
many of the city's government and cultural
institutions, to the northwest. In the late 1990s,
the area suffered from a range of economic and
social problems. In 2002, the San Francisco
Planning and Urban Research Association (SPUR)
created a redevelopment plan for the Mid-Market
neighborhood, which aimed to revitalize the area
https://www. epa.gov/smartgrowth/2010-national-award-
smart-growth-achievement-booklet.
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economically, socially, and physically, building
on the area's strong transit connections, cultural
institutions, historic buildings, and nonprofit and
social service agencies.182
SPUR identified the conversion of Mint Street
into a combined vehicle and pedestrian space as
one of several projects in the neighborhood that
could help jump-start revitalization. In 2005, the
San Francisco Redevelopment Agency drafted a
redevelopment plan for the neighborhood that
also highlighted the revitalization potential of
the plaza outside of the Mint building, one of the
few buildings in the neighborhood to survive the
1906 earthquake and fires.183 Before
redevelopment, this area was a neglected alley
often crowded with idling tour buses and parked
cars. Stormwater runoff in this area flowed
directly to the city's combined sewer system.
Exhibit 47. Mint Plaza is in a highly impervious area of the
city where nearly all Stormwater flows to the combined
sewer system.
B. PLANNING AND REGULATORY CONTEXT
The driving force behind converting the alley to
a public plaza came from a local developer,
Martin Building Company (MBC), which was
renovating several historic warehouses adjoining
the alley. MBC hoped to revitalize the area by
creating a safe and welcoming outdoor space
that would increase foot traffic and bring
customers to local businesses. A series of public
meetings to gather input into the design and
generate community support for the project
found that residents and other stakeholders
wanted a flexible public space that could serve a
variety of community needs.184
When the project was initiated, the city did not
require redevelopment projects to manage
Stormwater on-site. In fact, city regulations
required that Stormwater from the site be
conveyed to the combined sewer system. The
developer and design team worked closely with
the city to establish criteria for on-site water
quality treatment and recharge that were then
used to size the green infrastructure practices on
the site.185 City regulations also prohibited
disconnection of the adjacent roof downspouts
from the combined sewer system, so the
designers modified their initial plans, reducing
the impervious area served by green
infrastructure at the site.186 Both of these
regulatory obstacles to using green infrastructure
were addressed before the city issued updated
Stormwater design standards in 2010. MBC chose
to incorporate green infrastructure into the
plaza design in spite of these obstacles,
recognizing that environmental sustainability
would help with marketing the firm's projects
and ultimately increase sales prices.187
182 SPUR. Mid-Market Street Redevelopment District: A Plan
for Incremental Change. 2002. http://www.spur.org/
publications/spur-report /2002-01-16/mid-market-street-
redevelopment-district.
183 McDavid, Shelley. "Mint Plaza." In Public Interest Design:
Evaluating Public Architecture. 2013. http://issuu.com/
publicarchitecture/docs/pid_externship_report_2012-13_
final/33.
184 Gross, Jaime. "Mint Plaza in San Francisco." Topos. 2009:
62-64. http://www.cmgsite.com/fileadmin/cmg/home/
pro1ects/mint_plaza/CMG_Topos_67.pdf.
IBS persona[ communication with Scott Cataffa, CMG
Landscape Architecture, on Mar. 21, 2011.
186 Viani, Lisa Owens. "Fresh Mint Taste." Landscape
Architecture Magazine. Jul. 2011: 68-70.
187 McDavid op. cit.
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C. DESIGN AND PERFORMANCE
The site's stormwater management system
includes rain gardens, subsurface infiltration
chambers, and structural tree planters that
manage runoff from 18,000 square feet of
impervious area (Exhibit 48). Runoff flows either
directly to the infiltration chambers via a brick
slot drain or first to one of two rain gardens that
filter out pollutants before conveying runoff to
the infiltration chambers. The chambers are in
the center of the plaza to avoid existing utilities,
basements, and building foundations. They sit
atop sandy, native soil ideal for infiltration.188
Six structural tree planters add green space to
the plaza and additional infiltration area. The
planters help keep soil loose and maintain space
for a healthy root system while supporting the
sidewalk above.189 Inspection ports and cleanouts
under removable pavers in the patio area and
under a removable bench at the rain gardens
provide access for maintenance.
Designers sized the stormwater management
system to infiltrate runoff from the 5-year, 3-
hour storm event, or 0.79 inches of rainfall.190
This is the same standard the city uses to size
sewer pipes, providing assurance that the green
infrastructure practices could replace the
conventional collection and conveyance system.
During construction, the sandy soils beneath the
infiltration chambers were found to have a much
higher infiltration rate than the designers had
expected, resulting in infiltration of up to the
25-year, 24-hour storm. Larger events drain
overland to an existing gutter and inlet system in
5th Street. Over the course of a year, the new
Mint Plaza removes 500,000 gallons of
lOPyt rvrnl
•.IV. drill
Infiltration (hamlwr
drain rock basin
•Mt i.-.i M- Titter
Exhibit 48. Section detail of rain garden, slot drain, and subsurface infiltration chamber.
188 Gross op. cit.
189 Cataffa op. cit.
' Cataffa op. cit.
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stormwater that would have otherwise gone to
the city's combined sewer system.191
Since the construction of Mint Plaza, San
Francisco passed a stormwater management
ordinance192 and issued stormwater design
guidelines.193 The standards, which apply to both
new and redevelopment projects over 5,000
square feet, address the use of green
infrastructure for on-site treatment and
management of stormwater. Developers must
design projects to capture and treat 0.75 inches
of rainfall using best management practices.
Mint Plaza's design exceeds this standard by
capturing 0.79 inches of rainfall, and its actual
performance is likely better given the
unexpected high quality of the native soil.
Exhibit 49. Green infrastructure on Mint Plaza
accommodates the heavy use expected from a plaza in
the heart of downtown.
D. COSTS AND FUNDING
To finance the project, MBC created a special
assessment district called a Community Facilities
District. California permits property owners to
approve and levy a special real estate tax on
their own properties to support the issuance of
tax-exempt bonds by the Association of Bay Area
Governments' Finance Authority for Non-profit
Corporations. Proceeds from the bond sale can
be used to reimburse private, for-profit
developers (in this case MBC) for upfront
expenses to design and build public
improvements. Bonds were issued based on the
increased property tax assessments levied on five
surrounding privately owned properties that
benefited indirectly from the development of the
plaza.194 The Community Facilities District
covered the majority of the total $3.2 million
cost of the plaza.
In addition, the Public Utilities Commission
contributed close to $150,000, which covered a
major portion of the stormwater management
system;195 a local hotel contributed $200,000
towards the plaza to meet its open space
requirements;196 and the manufacturer of the
structural tree planters donated six for use at
Mint Plaza as a demonstration project.197
In addition to creating the special tax district,
MBC formed an independent, nonprofit
organization, Friends of Mint Plaza, to manage
maintenance and programming on the plaza,
including a farmers market and arts
performances.198 The organization also hosts
private, revenue-generating events at the site to
pay expenses.199
191 McDavid op. cit.
192 City of San Francisco. Ordinance No. 83-10. 2010.
http://www.sfbos.org/ftp/uploadedfiles/bdsupvrs/ordinance
s10/o0083-10.pdf.
193 City of San Francisco. San Francisco Stormwater Design
Guidelines. 2010. http://www.sfwater.org/Modules/Show
Document. aspx?documentlD=2779.
194 Personal communication with Michael Yarne, formerly of
MBC, on Mar. 30, 2011.
195 McDavid op. cit.
196 Viani op. cit.
197 Cataffa op. cit.
198 Gross op. cit.
199 Yarne op. cit.
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F. BENEFITS
The Mint Plaza project converted a former alley
into a vibrant, public space that hosts
community events for socioeconomically diverse
residents in a neighborhood with limited open
space. Converting the alley to a plaza created a
safe public environment and contributed to
revitalization of the surrounding neighborhood.
New hotels, restaurants, and cafes have opened
on or near the plaza, which also hosts food
trucks daily.
The stormwater management system removes as
much as 500,000 gallons of stormwater from the
city's combined sewer system annually.200 Given
the success of the design, San Francisco has used
the stormwater management system
implemented at Mint Plaza as a prototype for
other projects throughout the city that integrate
green infrastructure into the urban fabric in a
way that benefits the environment and the
neighborhood.201
r
Exhibit 50. Dance performances are some of the many
activities that bring people to Mint Plaza.
G. LESSONS LEARNED
• Regulations can sometimes create obstacles
to using green infrastructure. When the
project was being designed, San Francisco's
codes prohibited designers from directing the
runoff from adjacent roofs to the plaza's
infiltration chambers, reducing the project's
environmental benefits. The 2010 San
Francisco Stormwater Design Guidelines
changed that policy to encourage developers
to use green infrastructure to manage runoff
on-site, ensuring that future projects will not
face this limitation.
• Identifying funds for ongoing maintenance
when the project was being planned was key
to the public permitting process because it
allayed the city's concern about who would
be responsible for these costs.
Soil testing early in the project design phase
can help determine site constraints or (as in
the case of Mint Plaza) identify potential
cost savings that can be realized when good
infiltrative soils are native to the site. Mint
Plaza developers believed the project was
designed to manage the 5-year storm event
on-site, but thanks to the site's good soil,
the plaza actually manages the 25-year
storm event.
Designing public spaces to ensure they are
open and welcoming to all users can help
ensure long-term community support for the
project and help make revitalization more
socially equitable. Public programming and
movable seating independent of any of the
plaza businesses have helped attract
socioeconomically diverse users who do not
have to patronize any businesses to use the
site.202
200 McDavid op. at.
201 Ibid.
:Ibid.
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I. PROJECT TEAM
• Developer: Martin Building Company (MBC)
• Landscape architect: CMG Landscape
Architecture
• Civil engineer: Sherwood Design Engineers
• Regulatory agencies: City of San Francisco
and San Francisco Public Utilities
Commission203
1 Ibid.
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XI11. THORNTON
CREEK WATER
QUALITY CHANNEL
SEATTLE, WASHINGTON
A redeveloped parking lot manages
stormwater from a 680-acre sub-basin, improving water quality
in a compact, densely developed area, while providing much-
needed open space for residents.
Project type: Mixed-use development
Green infrastructure practices: Water quality channel
Completion date: 2009
This project is part of the city of Seattle's efforts
to revitalize the Northgate district, provide
much-needed public open space in this highly
urbanized neighborhood, and improve water
quality to benefit downstream habitat. The
Thornton Creek water quality channel provides
end-of-pipe water quality treatment for a 680-
acre sub-basin of the Thornton Creek watershed.
It diverts stormwater from an enclosed drainage
system under the site to a series of small ponds
landscaped with enhanced soils and native
plants, reducing flow rates and allowing
pollutants to settle out before the water reaches
the creek. A stakeholder group of community,
environmental, and business organizations
helped define the project goals and select a
design that protects the environment while
allowing new development. Seattle Public
Utilities built the stormwater facility as part of a
joint venture with the property owners.
A. SITE CONTEXT
The 9.1-acre project site is in the Northgate
district in northeast Seattle, with the Northgate
Mall and its surrounding surface parking lots to
the north, a transit hub and Interstate 5 (I-5) to
the west, a single- and multi-family residential
neighborhood to the east, and office and
commercial space to the south. Historically, the
site connected surrounding wetlands with
Thornton Creek's South Branch. However, in the
1950s, the proximity to I-5 transformed the area
with new retail development and large surface
parking lots. Part of this development included
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enclosing a portion of Thornton Creek between
the wetlands and its headwaters in a 60-inch
diameter storm pipe under 20 feet of fill and a 5-
acre parking lot.204
The Northgate district is in the highly urban,
11.6-square-mile Thornton Creek watershed.205
Stormwater runoff has caused erosion and water-
quality problems in Thornton Creek, an
important salmon habitat. The Washington
Department of Ecology lists Thornton Creek as
impaired for violation of bacteria, dissolved
oxygen, mercury, ammonia, temperature, and
pH standards.206 Thornton Creek drains to Lake
Washington in the heart of the Seattle-Bellevue
metropolitan area, which also suffers from
significant water quality impairment. Many in the
community identified the project site's location
between a highly urbanized 680-acre drainage
area and the headwaters of Thornton Creek's
South Branch as an ideal place to use green
infrastructure to improve the quality of
stormwater runoff before it reaches the creek.
Exhibit 51. The Thornton Place development is in a highly
impervious area of the city surrounded by acres of parking.
B. PLANNING AND REGULATORY CONTEXT
Seattle's 1993 Northgate Area Comprehensive
Plan sought to change the automobile-oriented
neighborhood into a mixed-use, more compactly
developed area that could accommodate
anticipated population growth while maintaining
a high quality of life.207 However, nearly a
decade of controversy and litigation followed as
property owners sought to redevelop the existing
parking lot for a mix of residential and
commercial uses, while environmental advocates
argued for unearthing the buried creek bed.208
In 2003, the mayor and city council brokered an
agreement that involved establishing the
Northgate Stakeholder Group, with 22 members
representing community, environmental, and
business interests. The city tasked the group
with reaching a compromise on the fate of the
site that would improve water quality in
Thornton Creek, provide community open space,
and generate economic development in the
Northgate district.209 The group ultimately
unanimously selected a design for the site, the
Thornton Creek water quality channel, that
would meet all of these goals.
As part of the brokered agreement, Seattle
Public Utilities entered into a joint venture with
the owners of the 9-acre site to acquire 2.7 acres
of the site for a stormwater management facility
(the "water quality channel") positioned to
maximize stormwater treatment and
204 SvR Design. Thornton Creek Water Quality Channel - Final
Report. Seattle Public Utilities and Restore Our Waters. 2009.
http://vvww.seattle.goV/util/cs/groups/public/documents/w
ebcontent/spu01_006146.pdf.
205 Ibid.
206 State of Washington Department of Ecology. "Water
Quality Assessment and 303(d) List." http://www.ecy.wa.
gov/programs/wq/303d/index.html. Accessed Jul. 23, 2015.
207 City of Seattle. Northgate Area Comprehensive Plan. 1993.
http://www.seattle.gov/Documents/Departments/
Neighborhoods/Planning/Plan/Northgate-plan.pdf.
208 SvR Design op. cit.
209 Ibid.
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development opportunities. Owners of the
northwest parcel would develop it with
multifamily housing and commercial space, while
owners of the southeast parcel would develop it
as senior housing.210
C. DESIGN AND PERFORMANCE
Many green infrastructure projects distribute
smaller treatment facilities throughout a
watershed. However, the Thornton Creek water
quality channel is designed to treat most storm
flows from two sub-basins, one that covers 20
acres and one that covers 660 acres, before the
runoff reaches Thornton Creek's South Branch.
Stormwater enters the facility at the upper
reaches of the site from two diversion structures,
one directing the majority of flows from the 660-
acre sub-basin into the water quality channel,
and one directing flows from the 20-acre sub-
basin into the upper cascade swale, which then
flows into the water quality channel. Ninety-one
percent of the average annual runoff travels
through the water quality channel, while peak
flows from large storm events overtop a barrier
to bypass the facility and continue through the
existing storm pipe. The bioswale terraces slow
down the water and allow sediments and
associated pollutants to settle out, while
providing a beautiful landscape of native
plants.211 Space constraints led designers to
modify conventional bioswale designs so that the
water quality channel accepts deeper flows. It is
expected to remove 40 to 80 percent of total
suspended solids and associated pollutants rather
than the standard 80 percent.212 Eighty-five
percent of the plants are native species. The
plantings include 172 native trees, 1,792 native
shrubs, and 49,000 native perennials, herbs,
grasses, rushes, and sedges.213
Exhibit 52. The Thornton Creek water quality channel provides a beautiful view and a rare spot of green space next to new
multifamily and senior housing.
210 Ibid.
211 Ibid.
212
SvR Design op. cit.
213 Landscape Architecture Foundation (LAP). "Thornton
Creek Water Quality Channel." http://landscapeperformance
.org/case-study-briefs/thornton-creek-water-quality-
channel. Accessed Jul. 23, 2015.
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D. COSTS AND FUNDING
Seattle Public Utilities constructed the green
infrastructure facility for a total cost of $14.7
million with a low-interest loan from the
Washington State Pollution Control Revolving
Loan Fund (Exhibit 53).214 Given the large
impervious area treated by the water quality
channel, it is a cost-effective solution for
improving stream water quality and habitat,
while providing a valuable public amenity.
Planning
Preliminary engineering
Design phase (design, project management, public meetings and outreach, cost estimating,
construction management)
Construction
Close-out
Other agency-specific work packages (Seattle Parks and Recreation, Seattle City Light,
Seattle Department of Transportation, Seattle Design Commission)
Staff-specific work packages (real estate services, communications, grants and contracts)
Total Project Cost
$99,026
$166,652
$2,987,988
$10,738,215
$169,744
$284,388
$14,446,013
Exhibit 53. Total cost estimate.
E. BENEFITS
The Thornton Creek water quality channel treats
680 acres of stormwater runoff in a highly
impervious watershed, removing suspended
solids and associated pollutants from 78 percent
of the average annual stormwater volume. While
helping to improve the water quality in Thornton
Creek, it also creates additional wildlife habitat
in an area that was previously a parking lot. The
maintenance staff have observed many wildlife
species using the channel, including stickleback
fish in the sediment pools, herons, and ducks.
Signs throughout the site educate visitors about
the environmental benefits of the project,
raising awareness of the importance of
stormwater management.
Beyond these environmental benefits, the
project created 2.7 acres of much-needed open
214 SvR Design op. cit.
215 LAP. "Thornton Creek Water Quality Channel." op. cit.
216 Benfield, Kaid. "Outstanding Urbanism, Transit, & State-
of-the-Art Green Infrastructure, Beautifully Mixed."
Switchboard: Natural Resources Defense Council Staff Blog.
Jun. 6, 2011. http://switchboard.nrdc.org/blogs/kbenfield
/outstanding_urbanism_and_state.html.
space in the Northgate district and provided
pedestrian links through the area, improving
access to nearby transit stops. In addition, the
Thornton Creek water quality channel has
catalyzed as much as $200 million in private
residential and commercial development.215 The
area gained 50,000 square feet of retail space
and 530 condominiums and townhomes, with a
mix of market-rate, subsidized, and senior
housing units.216 When Northgate's light rail
station opens in 2021,217 the area will be primed
for additional transit-oriented development that
will give residents and employees more
commuting options. The Thornton Place homes
are LEED Silver certified, and the entire site was
awarded LEED for Neighborhood Development
Silver certification. 218
217 Dunham-Jones, Ellen. "Grey, Green, and Blue: Seattle's
Northgate." A/Architect. Nov. 8, 2013. http://www.aia.org/
practicing/AIAB100516.
218 Blanton Turner. "Thornton Place Earns LEED for
Neighborhood Development Certification." Press release.
Oct. 17, 2013. http://stellar.com/images/upload/_pdf_2013
1017095519_1/ThorntonPlaceLEEDNDPressRelease_101713.pd
f.
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F. LESSONS LEARNED
• Green infrastructure can be a financially
viable approach to treat stormwater from
large drainage areas even in compact, urban
settings with physically constrained sites.
The project treats 78 percent of runoff from
680 acres while contributing to the vitality of
the neighborhood.
Collaboration and communication among
diverse interests can lead to effective
solutions for all parties even in seemingly
intractable situations. Compromise and the
establishment of the Northgate Stakeholders
Group was critical to breaking the political
logjam between advocacy groups and
developers.
G. PROJECT TEAM
• Owner: Seattle Public Utilities
• Concept design: Gaynor and Associates
• Civil engineering and landscape
architecture: SvR Design Company
• Hydraulic modeling and monitoring
services: Herrera Environmental
• Structural and electrical engineering: HDR,
Inc.
• Geotechnical engineering: Associated Earth
Sciences, Inc.219
219 Giraldo, Greg, Masako Lo, and Melanie Davies. "Thornton
Creek Water Quality Channel, Urban Water Quality and
Environmental Benefits." 2nd National Low Impact
Development Conference. Mar. 12-14, 2007.
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Smart Growth
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