EPA 230R16001

May 2016

www.epa.gov/smartgrowth

CITY GREEN: INNOVATIVE GREEN INFRASTRUCTURE 

SOLUTIONS FOR DOWNTOWNS AND INFILL LOCATIONS
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

Dominique Lueckenhoff – EPA Region 3

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 Geographic's current map policy
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

XIII.Thornton Creek Water Quality Channel......................................................................... 66
i 

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 contextsensitive green infrastructure compatible 

with the historic fabric.

• Green infrastructure fits into highly spaceconstrained 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.
1 

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 

 

1 For a complete description of different green 

infrastructure approaches, see: EPA. “What is Green 

Infrastructure?” https://www.epa.gov/green-infrastructure

/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.

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-greeninfrastructure. 
2 

Exhibit 2. Locations of profiled projects.

• Queens Botanical Garden, Flushing, New infrastructure in downtowns and infill locations 

York. by providing successful examples showing that: 

• The Kensington Creative and Performing • Careful site planning and selection of Arts High School, Philadelphia, practices allow green infrastructure to Pennsylvania. work on contaminated sites and sites with • The Radian Complex, Philadelphia, poor soils. Pennsylvania. • Historic properties can incorporate • The Sand River Headwaters Green 

context-sensitive green infrastructure Infrastructure Project, Aiken, South compatible with the historic fabric. Carolina. • Green infrastructure works in highly space • The Menomonee Valley Industrial Center, constrained sites and can even be a better Milwaukee, Wisconsin.

choice than conventional stormwater • The Uptown Normal Circle, Normal, Illinois. management approaches. • The Metro Green Line, St. Paul, Minnesota. • Municipalities are removing regulatory • Stapleton Greenway Park, Denver, obstacles to allow green infrastructure Colorado.

projects. • Santa Fe Railyard Park and Plaza, Santa Fe, • Green infrastructure can provide effective New Mexico.

stormwater management in arid climates • Mint Plaza, San Francisco, California. and areas where water rights are a • Thornton Creek Water Quality Channel, concern. Seattle, Washington. • Green infrastructure can be a costeffective approach to stormwater Although green infrastructure can be more management and can help drive economic challenging to implement in redevelopment development. projects compared to projects in undeveloped • Long-term maintenance can be addressed areas, the barriers are usually surmountable. by thoughtful upfront planning and These case studies help counter real and innovative approaches. perceived obstacles to using green 
3 

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 CONTEXTSENSITIVE 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 

 

3 A “25-year storm event” is a storm having a 25-year 

recurrence interval based on historical data. In other words, 

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, 

a storm of that magnitude has a 4 percent chance of 

happening in any given year.
4 

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 SPACECONSTRAINED 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. 
5 

D. MUNICIPALITIES ARE REMOVING REGULATORY OBSTACLES

TO ALLOW GREEN INFRASTRUCTURE PROJECTS

In many downtown and infill locations, longstanding 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 MANAGEMENT IN ARID CLIMATES 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. 
6 

F. GREEN INFRASTRUCTURE CAN BE A COST-EFFECTIVE 

APPROACH TO STORMWATER MANAGEMENT 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 MAINTENANCE 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 
7 

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.

 
8 

II.WALTHAM 

WATCH FACTORY 

WALTHAM, MASSACHUSETTS

Redevelopment of a historic mill 

complex along the Charles River 

improves water quality and the developer’s bottom line while 

providing new public access to the river.

Project type: Mixed-use development; historic preservation, brownfield redevelopment

Green infrastructure Pervious pavement, infiltration trenches, rain gardens, and tree plantings practices:

Phase 1: May 2009

Completion dates: Phase 2: March 2012

Phase 3: 2014

Green infrastructure is a prominent feature in 

the redeveloped Waltham Watch Factory, a 150-

year-old, 12-acre former mill complex in 

Waltham, Massachusetts, along the Charles 

River. The three-phase project involved 

rehabilitating and converting the historic mill 

complex to a mix of office, residential, retail, 

and restaurant space. The developer, Watch City 

Ventures, recognized that stormwater pollution 

threatened the health of the project’s main 

asset—the Charles River. Watch City Ventures 

engaged the Charles River Watershed Association 

to help incorporate green infrastructure into the 

site design. Pervious pavement, infiltration 

trenches, and rain gardens now help cleanse 

stormwater before it enters the Charles River. 

Building tenants and visitors can use walking 

paths to reach the river and can enjoy lush 

gardens in building courtyards, increasing the 

Watch Factory’s appeal and making it more 

valuable for its owners.

A. SITE CONTEXT

The project site is on the banks of the Charles 

River in the city of Waltham, a western suburb of 

Boston. The Upper/Middle Charles River is 70 

miles long, ending at the Watertown Dam where 

it connects to the Lower Charles River. The 

Upper/Middle Charles River watershed covers 
9 

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 

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 

 

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. cit. 7 Reed, Peter, and Kate Bowditch. The Watch Factory: A Case 

Study in Low Impact Development and Community 

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 

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/demonstrationprojects/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/26938380. 

Exhibit 3. The Waltham Watch Factory sits on the bank of 

the Charles River. Its redevelopment gives people access 

to the river.

spa MngBi
10

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 

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/massachusettsstormwater-handbook.html. 

Exhibit 4. The Waltham Watch Factory site plan shows how landscaped spaces were integrated throughout the project to 

reduce overall impervious area.
11

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 oilwater 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 13oF 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/casestudy-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.

Exhibit 5. Dennison Courtyard before and after redevelopment shows how new canopy trees, rain gardens, and tables make the

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space functional and inviting. 
12

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 220 $161 per linear foot $35,400 

Brown Street lot tree well with tree 2 $6,050 each $12,100 

Building 4 front courtyard infiltration trench 135 $142 per linear foot $19,200 

Pedestrian Courtyard rain garden 270 $622 per square foot $167,900 

Dennison Courtyard rain garden (including all landscape elements) 700 $286 per square foot $200,000 

Total $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 

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

/Project_shts_round_03/Project%20Sheets%20PDF_Commerci

al/BC_proj_sht_watch_factory.pdf. Accessed Sep. 2, 2015.

17 Watch City Ventures LLC. “Team.” http://www.waltham

watchfactory.com/team. Accessed Sep. 15, 2015.

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.

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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

 

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. 

Exhibit 8. Green infrastructure in the Watch Factory 

courtyards provides an attractive view for residents and a

place to gather.

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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 

practices: 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 onsite. 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.
15

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 

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 PERFORMANCE

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. 

Exhibit 9. The Queens Botanical Garden is in a dense 

residential and commercial area.

spa MngBi
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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

m

). 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. Stor 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

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. 

 

26 Ibid. 27 Bernstein op. cit. 28 Conservation Design Forum and Atelier Dreiseitl op. cit. 

The total cost for the visitor center and

administration building was $14 million,30 with 

29 Atelier Dreiseitl. Rainwater System Overview. 2003. 30 Bernstein op. cit.

tscteihcrK AKSB

Exhibit 10. Queens Botanical Garden visitor center and administration building site plan.

1. Main pedestrian entrance

New plaza and watercourse 

leading to fountain

Existing allee

Constructed wetland

2.

3.

4.

5. Native plant gardens

6. Green roof

7. Service area

8. Photovoltaic panels

9. Covered terrace

10. Cleansing biotope
17

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 lowerincome neighborhood with relatively few natural 

areas.

 

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 

 

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/ll86_basics.shtml. Accessed Aug. 

18, 2015.

sustainability into public buildings, leading to 

new city requirements. 

• Green infrastructure can be a focal point of a 

building’s design, helping to reestablish longsevered connections between the natural 

environment and residents.

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. cit. 

Exhibit 11. The space outside the administration building 

hosts performances and festivals.

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18

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

 

37 Queens Botanical Garden. “Project Team.” 

http://www.queensbotanical.org/103498/sustainable/

ParkingGarden_project/project_team. Accessed Aug. 17, 

2015.

Exhibit 12. The covered terrace where people gather 

overlooks the cleansing biotope.

tscteihcrK AKSB
19

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/projects/kensington-high-schoolcreative-and-performing-arts. Accessed Apr. 28, 2015.
20

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 afterhours 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. 

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.archdaily.com/187671/the-kensingtoncreative-and-performing-arts-high-school-smp-architects-andsrk-architects. 42 Rath, Jane, and Travis Alderson. “Champion for Change.” 

High Performing Buildings. Winter 2013. pp. 6-18. 

http://www.hpbmagazine.org/Case-Studies/KensingtonHigh-School-for-the-Creative-and-Performing-ArtsPhiladelphia-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-target8.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.

pdf. 

Exhibit 13. The KCAPA project site is a narrow lot 

surrounded by compactly developed neighborhoods. spa MngBi
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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.

REQUIREMENT DESCRIPTION PRACTICES IMPLEMENTED

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.

• 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-july-2015-resources. 
22

STORMWATER 

PRACTICE TYPE OF PRACTICE TOTAL DCIA(SQUARE FEET)

WQV (CUBIC FEET) STORAGE

REQUIRED PROVIDED (CUBIC FEET)

Porous pavement Infiltration 40,730 3,393 5,482 24,706

Pretreatment and 

underground storage Treat and release 66,080 5,507 5,507 41,660

Rain gardens Infiltration 8,580 715 2,193 4,507

Green roof Retention/evapotranspiration 22,040 824 824 4,010

Total 137,430 10,439 14,006 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 postdevelopment peak flow rates by 74 percent, 

54 percent, and 33 percent for the 15-, 50-, and 

100-year storms, respectively, compared to predevelopment peak flows. 

Two underground rainwater cisterns provide 

water for toilet flushing, although the 

seasonality 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

1. Green roof

2. Cool roof rain water collection

3. Outdoor classroom

4. School garden

5. Recycled landscape

6. Permeable paving

7. Porous grass paving

8. Rain garden

9. Elevated transit station

Exhibit 16. The site plan for KCAPA incorporated green infrastructure in multiple places.

tscteihcrK ARS │stcetihrc AMPS

 

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.
23

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 

 

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-greenroofs-green-cleaning-products. 

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 transportationrelated emissions are low. More 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 

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. 

Exhibit 17. Riders of the elevated rail line can see the rain

gardens in front of KCAPA as they pass by daily.

yhaprgotoh PnasoM/inkalH
24

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. 64 Stabert, Lee. “Learning Curve.” Grid. Nov. 2010. 

http://issuu.com/redflagmedia/docs/grid_2010.11?e=126199

5/5375442#search. 
25

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 neighborhoodserving 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-erdymchenry-architecture. 
26

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.

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 PERFORMANCE

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://www.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-Gardenarticle8747. 

Exhibit 18. The Radian Complex sits on the edge of the 

University of Pennsylvania’s campus along a commercial 

corridor.

spa MngBi
27

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 

upper terrace level with views of the street

includes a grove of trees separating the retail 

and residential components. 

STORMWATER MANAGEMENT PRACTICE SQUARE FEET PERCENT OF SITE

Green roof area 12,091 (650 intensive; 11,441 extensive) 17.8%

Conventional roof area draining to green roof 4,022 5.9%

Pervious pavers 2,155 3.2%

Planter boxes 1,470 2.2%

New trees 900 1.3%

Total 20,638 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. 

Exhibit 19. The green roof system on the Radian 

Complex diverts stormwater from the combined sewer 

system while giving residents an attractive view.

seiatcssoi AnonenP
28

FEATURE QUANTITY UNIT COST COST

Green roof, including protection layer, drainage media, perforated pipes, 

soil, and plantings 

12,000 ft2 $14 per ft2

$165,000

Pervious pavers, including site preparation, gravel base, and underdrain pipes 2,150 ft2 $25 per ft2 $53,500 

Stormwater drainage system, including detention basins and piping n/a n/a $158,500 

Total $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 

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.

Exhibit 22. Retail space on the first floor of the Radian 

Complex helps bring activity to the commercial corridor. 

erutecithcr AyrenHc MydrEis/ilbu KeretP
29

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://architypereview.com/project/theradian/?issue_id=561. 
30

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.

®ervi Rtenigleltn Iyitserivn UnsoemlC
31

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 

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 & SV-250 Fecal Coliform Bacteria. 2005. 

https://www.scdhec.gov/HomeAndEnvironment/Docs/tmdl_

horse.pdf. 75 Clemson University 2013 op. cit. 

Exhibit 24. Aiken’s downtown is next to Hitchcock Woods, 

which receives stormwater runoff from city streets.

spa MngBi
32

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 predevelopment discharge rates for the 2- and 

10-year, 24-hour storm events.77

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. 

Exhibit 25. Rain gardens in street medians help manage 

stormwater while providing attractive landscaping.

®ervi Rtenigleltn Iyitserivn UnsoemlC
33

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. cit. 
34

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 longisolated Menomonee River.

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

Land improvements and stormwater facility completed in 2005; private Completion date: 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.

eekauwil Mf oyite ChT
35

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 

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. 2013 

Menomonee Valley State of the Valley Report. 2014. 

http://www.renewthevalley.org/documents/160-resourcelibrary. 86 City of Milwaukee. Menomonee Valley 2.0 Comprehensive 

Area Plan. 2015. http://www.planthevalley.org/uploads/1/9

/0/4/19044935/menomonee_valley_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.

Exhibit 27. The MVIC site is located along the Menomonee 

River in a compactly developed part of the city.

spa MngBi
36

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 

 

91 Menomonee Valley Partners. Sustainable Design Guidelines 

for the Menomonee River Valley. 2006. http://www.renew

thevalley.org/media/mediafile_attachments/06/46-

guidelines. 92 Rouse and Bunster-Ossa op. cit. 

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 

93 Total Kjeldahl nitrogen is the sum of free ammonia and 

organic nitrogen compounds. 94 Misky and Nemke op. cit. 

Exhibit 28. The MVIC Stormwater Park manages stormwater 

runoff while providing a new public space with pedestrian 

and bicycle trails.

eekauwil Mf oyite ChT
37

continues to collect, hold, and filter rain water 

as expected. Maintenance primarily involves 

removing invasive species from the nowestablished 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.

esaticsso AkenW

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. cit. 98 Landscape Architecture Foundation (LAF). “Menomonee 

Valley Redevelopment and Community Park.” 

http://landscapeperformance.org/case-studybriefs/menomonee-valley-redevelopment-and-communitypark#/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_key=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. 
38

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 

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 LAF. “Menomonee Valley Redevelopment and Community 

Park.” op. cit. 103 Brownfield Renewal. “Menomonee Valley Industrial 

Center.” http://www.brownfieldrenewal.com/renewalaward-project-environmental_impact-menomonee_valley

_industrial_center-8.html. Accessed Jun. 24, 2015. 104 LAF. “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.jsonline.com/business/city-to-study-expansionof-menomonee-valley-industrial-center-b99448425z1-

292737391.html. 108 LAF. “Menomonee Valley Redevelopment and Community 

Park.” op. cit. 109 Memomonee Valley Partners, Inc. “Available Properties.” 

http://www.renewthevalley.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-Industrial-Center-and-CommunityPark-is-Model-of-Sustainable-Redevelopment.html. 

Exhibit 30. Trails through the park let visitors observe 

stormwater management in action.

esaticsso AkenW
39

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

 

111 Rouse and Bunster-Ossa op. cit. 112 Ibid.
40

VIII.UPTOWN 

NORMAL 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 

practices:

Underground cistern, filtration bogs, and structural cell and conventional 

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. 2011 

National Award for Smart Growth Achievement Booklet. 

https://www.epa.gov/smartgrowth/2011-national-awardsmart-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#.Va5Bik0w

_Gh. 
41

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 

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 PERFORMANCE

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. cit. 

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/2011/4/

Sustainability-as-catalyst-Uptown-Normal-Circle. 119 Ibid.

Exhibit 31. The Uptown Normal Circle sits at a formerly 

chaotic three-way intersection.

spa MngBi
42

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 (LAF). “Uptown

Normal Circle and Streetscape.” http://landscape

sales tax, a hotel/motel tax, a food and 

beverage tax, and establishment of a taxincrement 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-circleand-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. 

Exhibit 32. A cross section of the circle shows the flow of water through the system. 

stecithcre Aapscdan LtdauhcS reroH
43

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. More 

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 

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.” WTVP At 

Issue. Episode #2728. May 14, 2015. http://www.wtvp.org/

programming/ai/2-2728.asp. 126 LAF. “Uptown Normal Circle and Streetscape.” op. cit. 127 Ibid.

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/saferstreets-stronger-economies. 129 LAF. “Uptown Normal Circle and Streetscape.” op. cit. 

 

Exhibit 33. The Uptown Normal Circle serves multiple 

purposes in a small space previously used solely for traffic.

eyligh SttocSs/tecithcrAe apscdanL tdauhc SreroH

Exhibit 34. Stormwater features in the Uptown Normal 

Circle manage runoff while creating a beautiful park for 

the public to enjoy.

eyligh SttocSs/tecithcrAe apscdanL tduahcrr SeoH
44

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.

eyligh SttocSs/tecithcrAe apscdanL tdauhc SreroH
45

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 

practices:

Integrated tree trench system with structural soil, stormwater planters, rain 

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’ sevencounty 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 
46

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.130 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-ofway 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 PERFORMANCE

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 

 

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/healthycorridor-for-all. 

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 

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. 
47

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. 

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-project-of-the-year-final-nomination.pdf. 139 Eleria and Kelley op. cit. 140 Personal communication with Mark Doneux, Administrator, 

CRWD, on Nov. 25, 2015.

Exhibit 36. A tree trench system along University Avenue 

allows room for roots to grow in a highly trafficked area.

ticrist Dedhserat Wnioeg RloitapC
48

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 50

Counties Transit Improvement Board 30

Minnesota state 9

Ramsey County 7

Hennepin County 3

Metropolitan Council 1

City of St. Paul and Central Corridor 

Funders Collaborative <1

Exhibit 37. Total project funding. 

Source: Metropolitan Council. “Project Funding.” http://www.metro

council.org/Transportation/Projects/Current-Projects/CentralCorridor/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 

 

141 Metropolitan Council. “Metro Green Line Opens On Time 

and On Budget.” Jun. 14, 2104. http://www.metrocouncil

.org/News-Events/Transportation/News-Articles/METROGreen-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.

Exhibit 38. Signs help passersby understand the 

importance and function of rain gardens and other green 

infrastructure. 

ticrist Dedhserat Wnioeg RloitapC
49

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

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. cit. 

Exhibit 39. New businesses along the Green Line can 

benefit from the increased foot traffic it brings to 

neighborhoods. 

eivatroabllos Cerdn Furoidrro CalrtenC
50

X.SANTA FE

RAILYARD PARK 

AND PLAZA

SANTA FE, N

An abandoned railyard is transformed into a flourishing 

community activity center, including a 10-acre park that helps 

reduce stormwater runoff. 

EW MEXICO

Project type: Commercial development; public park and plaza; historic preservation; 

brownfield redevelopment

Green infrastructure 

practices:

Comprehensive site planning, water harvesting (cistern and water tower, 

swales, and two stormwater detention areas) 

Completion date: 2008

The Santa Fe Railyard Park and Plaza project

converted an abandoned railyard 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 Railyard 

Park and Plaza was historically used for 

agriculture by Native Americans and Spanish

settlers. Along the site runs the Acequia Madre, 
51

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

B. PLANNING AND REGULATORY CONTEXT

The planning process took years, as citizen 

activists strongly pushed to create a pedestrianoriented 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 predevelopment 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.railyardsantafe.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.

pdf. 

151 New Mexico Environment Department. “Brownfields 

Success Stories.” https://www.env.nm.gov/gwb/NMEDGWQB-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=P1007CTE.TXT. 

Exhibit 40. The Santa Fe Railyard Park and Plaza is a 

center of activity for the surrounding neighborhoods.

spa MngBi
52

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 PERFORMANCE

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, 

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/Santafenm/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.railyardpark.org/park-plaza/horticulture-in-thepark. Accessed Aug. 11, 2015. 160 Schwartz op. cit. 161 Ibid.

Exhibit 41. The Railyard Park incorporates extensive 

native plantings and naturalistic landscaping. 

moc.rkica fla viita Vtita CL
53

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. 

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. cit. 163 Personal communication with Suby Bowden, Suby Bowden 

+ Associates, on Apr. 28, 2011. 164 Crawford op. cit. 165 Railyard Stewards. “The Railyard Stewards.”

http://www.railyardpark.org. Accessed Aug. 11, 2015.

166 Crawford op. cit. 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.

Exhibit 42. The farmers market at the Railyard Plaza is a 

popular gathering place.

moc.rkica fla viita Vtita CL
54

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. 

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

Exhibit 43. The Santa Fe Railyard builds on the city’s 

unique assets to create a space that residents and 

visitors love.

mco.rckli fall viewsgo CnoR
55

XI. 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 fo

recreation and stormwater management. 

r 

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 singleand 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 

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.170

168 Carder, Carol. “New Life at an Old Airport.” Progressive 

Engineer. 2011. http://www.progressiveengineer.com/

features/new_life_old_airport.htm. 169 Ibid.

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. 
56

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 

requirements by incorporating green 

infrastructure throughout the site.

C. DESIGN AND PERFORMANCE

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.

• 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/

a0b9436a763f4470a648b3fca2de80b3/USDCM_Volume_3.pdf. 173 Personal communication with Dennis Arbogast, URS 

Corporation, on May 19, 2011.

171 City and County of Denver, Stapleton Redevelopment 

Foundation, and Citizens Advisory Board op. cit. 172 Denver Urban Drainage and Flood Control District. Urban 

Storm Drainage Criteria Manual Volume 3 – Best Management 

spa MngBi

Exhibit 44. The Stapleton Airport redevelopment site 

encompasses 4,700 acres. The yellow asterisk marks the 

Greenway Park.
57

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 

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-6-9-

billion-development-25-years-stapleton-taxes-pay. 177 Arbogast op. cit.

Exhibit 45. Homes in Stapleton have views of the 

stormwater facility and park. 

senikr EeyactS
58

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 bestselling 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 

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

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

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. 

179 Chroma Design. “Stapleton Greenway Park.” 

http://www.chromadesigninc.com/projects/greenway1.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/july-7-2011-why-stapleton-didntflood-2.

Exhibit 46. Walking and biking paths allow residents to 

use the open space that functions as a centralized 

stormwater management facility.

.cn I,noetlapt Syit Cster Fo/ ffoess GJ
59

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.
60

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: Rain gardens, infiltration chambers, and structural tree planters

Completion date: 2007

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 

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-awardsmart-growth-achievement-booklet. 

181 Among other awards, this project received EPA’s National 

Award for Smart Growth Achievement. See: EPA. 2010 

National Award for Smart Growth Achievement Booklet. 
61

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.

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-streetredevelopment-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/

projects/mint_plaza/CMG_Topos_67.pdf. 185 Personal 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.

Exhibit 47. Mint Plaza is in a highly impervious area of the 

city where nearly all stormwater flows to the combined 

sewer system.

spa MngBi
62

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

Exhibit 48. Section detail of rain garden, slot drain, and subsurface infiltration chamber.

188 Gross op. cit. 189 Cataffa op. cit. 190 Cataffa op. cit. 

erutecithcr Aeapscdan LGMC
63

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. 

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?documentID=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. 

Exhibit 49. Green infrastructure on Mint Plaza 

accommodates the heavy use expected from a plaza in 

the heart of downtown.

erutecithcr Aeapscdan LGMC
64

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 

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. cit. 201 Ibid.202 Ibid.

Exhibit 50. Dance performances are some of the many 

activities that bring people to Mint Plaza.

aazl PtinM fs odnieFr
65

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

203 Ibid.
66

XIII. 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 muchneeded 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 
67

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 waterquality 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.

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://www.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.

Exhibit 51. The Thornton Place development is in a highly 

impervious area of the city surrounded by acres of parking.spa MngBi
68

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 subbasin 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 

210 Ibid. 211 Ibid. 212 SvR Design op. cit.213 Landscape Architecture Foundation (LAF). “Thornton 

Creek Water Quality Channel.” http://landscapeperformance

.org/case-study-briefs/thornton-creek-water-qualitychannel. Accessed Jul. 23, 2015.

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.

snommoa Ciedipika Wi velabe MoJ
69

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.

ACTIVITY COST

Planning $99,026

Preliminary engineering $166,652

Design phase (design, project management, public meetings and outreach, cost estimating, 

construction management) $2,987,988

Construction $10,738,215

Close-out

Other agency-specific work packages (Seattle Parks and Recreation, Seattle City Light, 

Seattle Department of Transportation, Seattle Design Commission) $169,744

Staff-specific work packages (real estate services, communications, grants and contracts) $284,388

Total Project Cost $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 LAF. “Thornton Creek Water Quality Channel.” op. cit. 216 Benfield, Kaid. “Outstanding Urbanism, Transit, & Stateof-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.” AIArchitect. 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.
70

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.