Green Infrastructure

1. www.planning.org
David C. Rouse, aicp, and Ignacio F. Bunster-Ossa
American Planning Association
Planning Advisory Service
Report Number 571
Green Infrastructure:
A Landscape Approach
Green
Infrastructure
A
merican
Planning
Association
PAS
Report
Number
571

2. The Planning Advisory Service is a subscription service offered by the Research Department of the
American Planning Association. Four reports are produced each year. Subscribers also receive PAS
Memo and PAS QuickNotes, and they have access to the Inquiry Answering Service and other valuable
benefits. To learn more, visit www.planning.org/pas/index.htm.
W. Paul Farmer, faicp, Chief Executive Officer; Sylvia Lewis, Director of Publications; William R. Klein,
aicp, Director of Research.
Planning Advisory Service Reports are produced in the Research Department of APA. Timothy Mennel,
Editor; Lisa Barton, Design Associate.
Missing and damaged print issues: Contact Customer Service, American Planning Association, 205 N.
Michigan Ave., Suite 1200, Chicago, IL 60601 (312-431-9100 or customerservice@planning.org) within 90
days of the publication date. Include the name of the publication, year, volume and issue number or month,
and your name, mailing address, and membership number if applicable.
© January 2013 by the American Planning Association.
APA’s publications office is at 205 N. Michigan Ave., Suite 1200, Chicago, IL 60601–5927.
APA headquarters office is at 1030 15th St., NW, Suite 750 West, Washington, DC 20005–1503.
E-mail: pasreports@planning.org
David C. Rouse, aicp, is a planner and landscape architect at Wallace, Roberts & Todd (WRT) in
Philadelphia. His projects include comprehensive plans for cities, counties, and regions; parks
and open space system plans; urban design plans; and zoning and development regulations.
Rouse is an active participant in national initiatives of the American Planning Association
and speaks across the country on topics ranging from the role of planning and design in pub-
lic health to green infrastructure and urban forestry.
Ignacio F. Bunster-Ossa is a landscape architect and urban designer whose work is consistently
recognized for design innovation. He is a leading practitioner of Landscape Urbanism, an
approach to urban design based on the fusion of ecology, community identity, infrastruc-
ture, recreation, and public art. Bunster-Ossa directs WRT’s landscape architecture studio
in Philadelphia as well as many of the firm’s large-scale landscape projects. He is a Harvard
Loeb Fellow and periodically lectures, teaches, writes, and serves on design award juries.
Contributors
Bj Adigun is program coordinator at CH2M Hill in Syracuse, New York. Patrice Carroll is
senior planner for the City of Seattle. Bill Cesanek, aicp, is vice president in the Edison, New
Jersey, office of CDM Smith. Andrew Dobshinsky, aicp, is an associate at WRT in Philadelphia.
Greg Dorolek is senior associate and landscape architect at Wenk Associates in Denver. Dave
LaClergue is an urban designer for the City of Seattle. Tom Leader is principal of Tom Leader
Studio in Berkeley, California. Mia Lehrer is president of Mia Lehrer + Associates in Los
Angeles. Brian Marengo is senior water resources technologist in the Philadelphia office of
CH2M Hill. Dee Merriam works on the relationship between health and the built environ-
ment; she has a particular interest in developing synergies between water management and
public access to outdoor space. Leah Rominger is staff consultant and landscape designer in the
Philadelphia office of CH2M Hill. Terry Schwarz, aicp, is the director of Kent State University’s
Cleveland Urban Design Collaborative. Eric Tamulonis is a landscape architect at WRT in
Philadelphia who focuses on the planning and design of parks and open space systems, as
well as institutional, historical, and academic landscapes. Nancy Templeton, aicp, is an associ-
ate at WRT in Philadelphia. Karen Walz, faicp, is principal of Strategic Community Solutions,
a consulting firm based in Dallas. Bill Wenk is founder and president of Wenk Associates in
Denver.
Cover design by Lisa Barton; this report is printed on recyclable paper.
Cover image: Aerial visualization of green infrastructure practices in Philadelphia, as envisioned by
the Philadelphia Water Department’s Green City Clean Waters Program. Prepared by WRT

3. GREEN INFRASTRUCTURE:
A LANDSCAPE APPROACH
Chapter 1: Introduction................................................................................................................ 1
Chapter 2: Landscape Planning, Design, and Green Infrastructure........................................... 5
Historic Antecedents......................................................................................................6
Definitions of Landscape and Green Infrastructure................................................10
Key Concepts................................................................................................................. 11
Chapter 3: Green Infrastructure in Practice.............................................................................. 17
Planning and Design Principles..................................................................................18
Scales of Planning Practice..........................................................................................22
Green Infrastructure in the Planning Process...........................................................28
Landscape Architecture and Green Infrastructure...................................................36
Conclusion.....................................................................................................................41
Chapter 4: Case Studies............................................................................................................. 47
Green Infrastructure at the Regional Scale
Cleveland and Northeast Ohio: Green Infrastructure for a City in Transition....48
North Texas: Returning to the Trinity........................................................................56
Green Infrastructure in Large Cities
Philadelphia: Making the Greenest City in America...............................................68
Seattle: A City’s Journey toward Sustainability........................................................76
Green Infrastructure in Smaller Communities
Lancaster, Pennsylvania: Managing Stormwater Pollution and
Enhancing Community through Green Infrastructure........................................84
Lenexa, Kansas: Rain to Recreation............................................................................93
Onondaga County, New York: Save the Rain.........................................................100
Parks, Greenways, and River Corridors as Green Infrastructure
Birmingham, Alabama: A Green Infrastructure Movement.................................107
Los Angeles River: Using Green Infrastructure to Revitalize a City................... 118
Louisville Metro, Kentucky: Application of Green Infrastructure
from Region to Site.................................................................................................125
Menomonee Valley Park and Redevelopment, Milwaukee..................................135
Summarizing the Case Studies.......................................................................................141
Appendix: A Model Regulatory Framework for Green Infrastructure..................................... 145
References................................................................................................................................ 155
David C. Rouse, aicp, and Ignacio F. Bunster-Ossa
TA B L E O F C O N T E N T S

5. 1
In recent years the term “green infrastructure” has assumed a lead-
ing position in the lexicon of planners and designers. At the city
and regional scales, it has been defined as a multifunctional open-
space network. At the local and site scales, it has been defined as a
stormwater management approach that mimics natural hydrologic
processes. This PAS Report explores the unifying concept of land-
scape as green infrastructure—the visible expression of natural and
human ecosystem processes that work across scales and contexts to
provide multiple benefits for people and their environments.
CHAPTER 1
Introduction
▲

6. 2 Green Infrastructure: A Landscape Approach
Infrastructure is commonly defined as the facilities and services necessary
for a society, community, or economy to function. In this definition, facilities
and services can be grouped into two broad categories: “hard” and “soft”
infrastructure. Hard infrastructure generally refers to transportation (roads,
mass transit, etc.), utilities (water, sewer, etc.), and other physical networks.
Soft infrastructure encompasses the institutional systems (education, health
care, governance, etc.) that are required to meet the economic, social, and
other needs of a community. While green infrastructure has an important
role to play as soft infrastructure (e.g., by building capacity—improved
health, job opportunities, community cohesion, etc.), this report addresses
it primarily in the context of hard infrastructure.
In the 20th century, hard infrastructure most often referred to the physical
or “gray” systems engineered and constructed by humans, such as roads,
utilities, and flood control works. In this paradigm, natural or “green” sys-
tems and the services they provide for society were treated separately. Today,
however, our green infrastructure lens views “gray” and “green” systems
as interconnected ones that must be considered together to sustain a func-
tioning society, community, or economy. In particular, the “green” systems
are active, visible, and integrated into the
human-shaped landscape—a fundamental
paradigm shift.
This broader view recalls an earlier
time when natural factors determined the
trajectory of a civilization and its built infra-
structure. From the beginning of recorded
history, the natural environment shaped
where people chose to settle. Early towns
and cities were built on sites where natural
features provided key advantages, such as
access to a navigable river or harbor, pro-
tection from attack, or efficient disposal of
waste and effluent. Where the terrain was
accessible, roadways and aqueducts were
built to connect settlements and sustain
them with water. Urban development
often flourished where such advantages
coalesced.
Over time, infrastructure evolved from
being primarily the work of nature (landscape conditions influenced by
people to meet their needs) to the work of humankind. Constructed infra-
structure proliferated with the Industrial Revolution, as more sophisticated
water supply and waste disposal works were needed to support growing
urban populations and as new forms of transportation—first the railroad
and then the automobile—led to metropolitan expansion. By the middle of
the 20th century, engineered infrastructure had eclipsed landscape (in its role
as nature-based infrastructure) as the primary driver of urban development.
The availability of transportation, utility, and other gray infrastructure
systems enabled accelerated metropolitan expansion in the post–World War
II era. Between 1950 and 2000, the U.S. population increased by 80 percent
while the nation’s urban land area, following auto-oriented development
patterns, increased at a much greater rate (over 400 percent by one measure).
Awareness of the environmental impacts of this urbanization—industrial
pollution, resource depletion, degraded air and water quality, and so on—­
increased during the 1960s; in 1969 a “tipping point” was reached when an
oil slick and debris on the Cuyahoga River in Cleveland caught fire, attracting
national attention. Soon after, the first Earth Day was celebrated onApril 22,
Streetside swale and adjacent
pervious concrete sidewalk
in the High Point neighborhood
of Seattle
U.S. Environmental Protection Agency

7. Chapter 1. Introduction 3
1970, marking the germination of the contemporary environmental move-
ment and a growing chorus of citizen concerns about issues such as loss of
open space, traffic congestion, and urban decline. State and local govern-
ments have as a result undertaken comprehensive planning and growth
management initiatives, with planners playing key roles.
Grass only partially covered by
a perforated surface makes for a
pervious parking lot.
iStockphoto.com/Oks_Mit
Key to these developments was a growing awareness of landscape as
both a vital resource needing protection and a countervailing force that
could be used to positively shape city and regional development patterns.
Landscape architect Ian McHarg was a seminal figure in raising environ-
mental awareness through his writings, television show (The House We Live
In), professorship at the University of Pennsylvania, and practice with the
firm Wallace McHarg Roberts & Todd. His book Design with Nature (1969)
established an influential methodology for analyzing land’s suitability for
development or conservation, while his work as an advisor to the federal
government during the Johnson administration led to establishment of the
National Environmental Policy Act (NEPA), “the world’s first institutional-
ized system of environmental impact reviews” (Yaro 1998, xi). NEPArequires
analysis of the impacts of any proposed federal or federally funded action
determined to significantly affect the quality of the human environment.
This groundwork has become ever more critical to today’s planning and
urban design practitioners, as they grapple with key questions such as: How
can cities and regions become environmentally, economically, and socially
sustainable? How can cities large and small, some of which have experienced
decades of population decline, become more desirable, attractive, and equi-
table places of opportunity for greater numbers of people to live? And how
can the urban environment integrate a working landscape that promotes the
health and well-being of people and ecosystems at all scales, from the region
and city to singular development sites? In essence, what is the urban and
regional pattern for a sustainable future, how can it be implemented, and
how can planners and designers play leading roles in addressing these issues?
A key to answering these questions lies in the use of the landscape to
perform ecological functions—such as cleansing urban waters, replenish-
ing aquifers, scrubbing airborne pollutants, sequestering carbon, absorbing
floodwaters, moderating microclimates, and sheltering wildlife—while
simultaneously supporting societal functions such as physical activity and
recreation, mobility, food and fiber production, economic productivity, cul-
tural identity, and community cohesion. Taken broadly to mean a network
of spaces, places, and design elements—natural or constructed, public or
private, local or regional—that provides such benefits, landscape looms large
as a catalyst to achieving sustainable futures for cities and regions.

8. 4 Green Infrastructure: A Landscape Approach
This report explores the concept of landscape as green infrastructure—
the physical manifestation of complex, multifunctional systems that span
disciplines (planning and design); contexts (urban, suburban, and rural);
and scales (region, city, neighborhood, and site). Chapter 2 elaborates on
the evolution and basic attributes of this concept. Chapter 3 addresses its
implications for practitioners, with a focus on integrating the work of urban
planners and landscape architects. It lays out a set of unifying principles
that can be used by different professions to advance green infrastructure
solutions. Chapter 4 presents case studies drawn from communities across
the United States that are implementing these principles through green
infrastructure initiatives in a variety of contexts and across scales.
Millennium Park in downtown
Chicago, with its mix of built
and landscape infrastructural
elements, has become a major
tourist destination.
Carolyn Torma

9. 5
What is a “landscape” approach to green infrastructure? How is it
more than just implementing green infrastructure measures at vari-
ous scales, from green roofs and rain gardens to regional greenways
and open space? The answer lies in conceiving of landscape as an
integrated whole, as the “scene” across the land that encapsulates
the adaptation and manipulation of natural form and processes for
the purpose of human habitation. A landscape approach to green
infrastructure entails a design vision that translates planning strat-
egy into physical reality while heeding the ecological and cultural
characteristics of a particular locale—whether a region or an indi-
vidual building site. It is, by necessity, an approach that involves
aesthetics: what a place should look like as informed by the people
who live on the land, their past, and their aspirations.
CHAPTER 2
Landscape Planning, Design,
and Green Infrastructure
▲

10. 6 Green Infrastructure: A Landscape Approach
In this context, green infrastructure becomes both “effective” as an agent
of environmental quality and “affective” as an expression of local conditions.
A landscape approach to green infrastructure requires considering not only
how infrastructure could improve water or air quality but also how, say, a
rain garden, constructed wetland, or greenway might engender a sense of
community identity. It raises the question: How and where should green
infrastructure be placed on the land? It is more than a strictly functional
question, as it both enriches and complicates practice.
This chapter provides an overview of the evolution of the idea of land-
scape as green infrastructure, followed by a discussion of key concepts
explored in Chapters 3 and 4.
HISTORIC ANTECEDENTS
Human settlements have long been integrated
into the larger landscape. The Mesa Verde cliff
dwellings in Colorado, inhabited between about
550 and 1300 by the Anasazi, are an advanced
and dramatic example, where pueblo architec-
ture seems fused with its sandstone surround-
ings (Figure 2.1). Similarly, pre-Columbian
Machu Picchu in Peru is built from the rocks
on which it stands, with stone walls angled to
match the slopes of the supporting mountain,
mimicking the larger landscape.Ancient Babylon
is etched in the imagination as a garden city
with the allure of bountiful and soothing urban
nature—an image that migrated throughout the
Middle East, Moghul India, Moorish Spain, and
beyond to theAmericas during Spanish coloniza-
tion, where it took the form of the walled garden
and tree-laden courtyard. Such forms also tended
to have a practical, infrastructural component—
the gardens of Alhambra, constructed by the
Moorish rulers of Granada in the 14th century,
incorporated water features that helped cool the
complex (Figure 2.2).
Figure 2.2. The gardens of
Alhambra, in Spain
WRT
Figure 2.1. Mesa Verde
National Park
WRT

11. Chapter 2. Landscape Planning, Design, and Green Infrastructure 7
In 1681, William Penn advanced the integration of landscape and city in
America by envisioning Philadelphia as a “Green Country Towne.” Penn
had witnessed firsthand the devastation in London wrought by the bubonic
plague followed soon after by the great fire. His vision of a city comprising
large estates, each well-buffered from neighbors, thus had as much to do
with public health and safety as with lush greenery. In 1858, Philadelphia
established Fairmount Park (today one of the largest urban parks in the
nation) as a way to improve and protect the Schuylkill River as the city’s
main water supply while also providing access to cooling breezes, expansive
views, and recreational space (Figure 2.3).
The idea of landscape as infrastructure gained further currency
through Frederick Law Olmsted’s 1870s proposal for Boston’s Back
Bay, a “noxious tidal swamp” that lay stagnant with effluent, as part of
an “Emerald Necklace,” a seven-mile corridor of parkland connecting
Boston Common with Franklin Park. In addition to providing needed
parkland, Olmsted’s design for the “Fens” improved drainage, help-
ing to flush and cleanse the waters and mitigate local flooding. In the
early 1900s, Frederick Law Olmsted Jr., as a member of the McMillan
Commission, extended the concept of the Boston Fens to the Anacostia
River in Washington, D.C. The commission was entrusted with the
renovation of the National Mall and other key public areas to com-
memorate the 100th anniversary of the founding of the nation’s capital.
In an effort to rid the Potomac River of its “malarial flats” and bring
about a healthier, recreation-oriented landscape, Olmsted proposed the
addition of wetlands that could trap and filter urban effluent—a clear
use of nature to promote public health and well-being.
Other professionals advanced the practice of landscape-level planning and
design during an era in which landscape architecture and urban planning
were not separate professions. Examples include Charles Eliot’s Plan for the
Metropolitan Park System of Boston (1899) and his nephew Charles Eliot II’s
Open Space Plan for the Commonwealth of Massachusetts (1928). Perhaps best
known for his parks and boulevard plan for Kansas City, Missouri, imple-
mented between 1890 and 1920, George Kessler also designed a comprehen-
Figure 2.3. Fairmount Park,
Philadelphia
WRT

12. 8 Green Infrastructure: A Landscape Approach
sive open-space system of drainageways, parks, and boulevards for Dallas
after the devastating flood of 1908. Renowned for his naturalistic approach
to garden design, the versatile Warren Manning in 1923 prepared a plan
for the entire United States that delineated “future urban areas, recreation
areas, commercial tracks, and recreation ways” (Figure 2.4). While Manning’s
plan was never published in its entirety, it represents an early example of
landscape planning at a “mega” scale.
Olmsted’s concept of a “working nature” was preempted for decades as
automobiles proliferated and the construction of highways and other gray
infrastructure fueled metropolitan expansion in the post–World War II era.
But it reemerged as a core method for urban planning and design in the latter
part of the 20th century as popular concern over the effects of development
grew. In Design with Nature (1969), Ian McHarg established natural process
as the basis for limiting development impacts on natural resources, and
he pioneered the so-called overlay or “layer cake” method of analyzing a
landscape to determine its fitness for development. This method begins with
overlay mapping of multiple ecological factors, including climate, geology,
hydrology, soils, vegetation, and wildlife. A suitability analysis based on
synthesis of these factors is then conducted to reveal the land’s intrinsic abil-
ity to withstand the impact of development on valuable natural resources.
McHarg, in essence, established the notion of ecological services—that na-
ture has a direct and measurable value to human well-being by providing
benefits such as air quality, water quality and supply, soil conservation, and
wildlife protection. The precepts of Design with Nature have been absorbed
by several generations of landscape architecture and planning professionals
and institutionalized in federal and state environmental regulations, thus
influencing the development of much of America’s urban landscape. For
example, the federal National Environmental Policy Act (NEPA), California
Environmental Quality Act (CEQA), and similar legislation in several other
states require the documentation of environmental and social factors as a
Figure 2.4. Warren Manning’s
national plan

13. Chapter 2. Landscape Planning, Design, and Green Infrastructure 9
basis for the evaluation of development alternatives, leading to preferred
alternatives that reduce impacts on those resources.
McHarg’s work was further advanced by Anne Whiston Spirn, his suc-
cessor as chair of the University of Pennsylvania’s landscape architecture
program, in The Granite Garden: Urban Nature and Human Design (1984).
This book focused on the ecology of urban areas: the matrix of noise, dust,
pollution, insolation, stormwater runoff, wind, wildlife, and the like that
can be mitigated and improved via urban landscapes. The book’s opening
paragraph sets the ethical basis for design:
Nature pervades the city, forging bonds between the city and the air, earth, water,
and living organisms within and around it. In themselves, the forces of nature
are neither benign nor hostile to humankind. Acknowledged and harnessed, they
represent a powerful resource for shaping a beneficial urban habitat; ignored or
subverted, they magnify problems that have plagued cities for centuries, such as
floods and landslides, poisoned air and water. (Spirn 1984, xi)
The impetus to reintegrate nature into patterns of human settlement has
acquired greater urgency today. This stems in part from the need to mitigate
and adapt to the effects of climate change by establishing more energy-
efficient mobility systems and creating resilient cushions against trends
such as increased heat, drought, flooding, and sea level rise. Moreover,
such reintegration can promote sustainability by abetting increases in the
density of urban settlements. While denser settlements can help conserve
energy (in part by facilitating the use of public transportation, bicycling,
and walking as alternatives to automobiles), they also heighten the need
for greenery and opportunities for outdoor recreation as development
catalysts.
These forces have led to a search for new, integrative modes of practice in
which planning and design concerns overlap and disciplinary boundaries
become blurred. A prime example is landscape urbanism, which positions
landscape as the foundation for urban design on all scales, from the macro
(e.g., floodways, greenways, and parks) to the micro (e.g., the pattern and
character of blocks, streets, and public spaces). In this approach, buildings
integrate landscape features such as vegetated walls and roofs as part of a
systems approach to conserving energy, sequestering carbon, moderating
microclimates, and absorbing stormwater runoff. Other similar approaches
that favor integration of natural processes with the built environment include
sustainable urbanism (Farr 2007); ecological urbanism (associated with the
Harvard Graduate School of Design; see Mostafavi and Doherty 2010); and
biourbanism, which “focuses on the urban organism, considering it as a
hypercomplex system, according to its internal and external dynamics and
their mutual interactions” (www.biourbanism.org/biourbanism).
At the city and regional scales, open space planning has gained promi-
nence in recent decades as a means to protect natural, agricultural, and
other open lands from development pressures. The following is a typical
definition of open space:
Open space may be defined as an area of land or water that either remains in its
natural state or is used for agriculture, free from intensive development for resi-
dential, commercial, industrial or institutional use. Open space can be publicly
or privately owned. It includes agricultural and forest land, undeveloped coastal
and estuarine lands, undeveloped scenic lands, public parks and preserves. It
also includes water bodies such as lakes and bays. The definition of open space
depends on the context. In a big city, a vacant lot or a small marsh can be open
space. A small park or a narrow corridor for walking or bicycling is open space,
though it may be surrounded by developed areas. Cultural and historic resources
are part of the heritage of New York State and are often protected along with open
space. (New York 2009)

14. 10 Green Infrastructure: A Landscape Approach
In contemporary planning practice, open space plans and variations such
as parks and recreation plans, resource conservation plans, and greenway
and trail plans are prepared either as stand-alone documents or as topical
elements of comprehensive plans. Greenways—linear open-space corridors
like those along watercourses and abandoned rail lines that provide multiple
ecological, recreational, economic, and cultural / historic values—have seen
a rise in interest in recent decades. Open space and greenway plans are in-
creasingly being repurposed as green infrastructure plans that emphasize
the environmental, economic, and social benefits provided by physical re-
source networks. At area and site scales, the term “green infrastructure” is
often used to refer to stormwater management practices that mimic natural
hydrological processes as opposed to “hard” engineered solutions. These
two definitions of green infrastructure are discussed below.
DEFINITIONS OF LANDSCAPE AND GREEN INFRASTRUCTURE
Landscape has traditionally been defined as an aesthetic resource, such as an
expanse of scenery, or as the overall geography of a region. In the words of
theAmerican Society of LandscapeArchitects (ASLA), “landscape architects
design the built environment of neighborhoods, towns and cities while also
protecting and managing the natural environment, from its forests and fields
to rivers and coasts. Members of the profession have a special commitment
to improving the quality of life through the best design of places for people
and other living things” (www.asla.org/nonmembers/What_is_Asla.cfm).
Green infrastructure is relatively new to the lexicon of urban plan-
ning and landscape design. According to Firehock (2010), the term was
first used in a 1994 report on land conservation strategies by the Florida
Greenways Commission. The intent was to elevate the societal value and
functions of natural lands and systems to the same level of importance as
gray infrastructure:
The Commission’s vision for Florida represents a new way of looking at conser-
vation, an approach that emphasizes the interconnectedness of both our natural
systems and our common goals and recognizes that the state’s ‘green infrastructure’
is just as important to conserve and manage as our built infrastructure. (Florida
Greenways Commission 1994)
Mark Benedict and Ed McMahon (2006) of the Conservation Fund defined
green infrastructure as
a strategically planned and managed network of wilderness, parks, greenways,
conservation easements, and working lands with conservation value that supports
native species, maintains natural ecological processes, sustains air and water re-
sources, and contributes to the health and quality of life forAmerica’s communities
and people.
More recently, a second definition of green infrastructure evolved from
the need to address the water-quality impacts of urban stormwater runoff in
response to the Clean WaterAct and related regulatory mandates.According
to the U.S. Environmental Protection Agency (EPA; www.epa.gov/owow/
NPS/lid), green infrastructure refers to “systems and practices that use
or mimic natural processes to infiltrate, evapotranspirate (the return of
water to the atmosphere either through evaporation or by plants), or reuse
stormwater or runoff on the site where it is generated.” While the Florida
Greenways Commission and Conservation Fund definitions emphasize large
landscape elements such as parks, natural areas, greenways, and working
(agricultural and forest) lands, the EPA identifies smaller-scale features in
urban contexts—green roofs, trees, rain gardens, vegetated swales, pocket
wetlands, infiltration planters, vegetated median strips, and so on—as typi-
cal components of green infrastructure.
As professions, planning and land-
scape architecture share common roots.
Founded in 1900, the nation’s first
Department of LandscapeArchitecture at
Harvard University’s Graduate School of
Design addressed a wide range of scales
and included what may have been the first
course in city planning. Over time, how-
ever, a split between design and planning
occurred within the department, with
landscape architects focusing on smaller-
scale design (e.g., of country estates) while
the nation’s first Department of City and
Regional Planning was founded in 1923
to address large-scale physical planning
(Steiner 2010). The bifurcation of the fields
foreshadowed a broader societal trend in
the 20th century toward specialization
and separation of professional disciplines.
In the 21st century, interrelated problems
such as automobile dependency and traf-
fic congestion, combined sanitary and
storm sewer overflows, degraded air
and water quality, and chronic diseases
related to lifestyle (e.g., obesity and dia-
betes) are making the limitations of “silo”
thinking increasingly apparent. Because
of its multifunctional, integrative nature,
green infrastructure can play a major role
in addressing these problems. Compared
to other, more specialized professions,
planners and landscape architects are es-
pecially well-suited to bring holistic green
infrastructure solutions to the planning
and design of cities, neighborhoods, and
other aspects of the physical environment.
In doing so, they can reestablish the com-
mon ground of the two professions.
▲ GREEN INFRASTRUCTURE
AND THE PROFESSIONS OF
PLANNING AND LANDSCAPE
ARCHITECTURE
▲

15. Chapter 2. Landscape Planning, Design, and Green Infrastructure 11
This report seeks to bring these two definitions together and enrich
them by viewing green infrastructure through the lens of landscape—the
physical manifestation of processes that connect the built and natural
environments, performing multiple functions and yielding associated
benefits for the health and well-being of people and wildlife. This per-
spective links physical form and aesthetics with function and outcomes
(benefits); natural habitats with landscapes managed by humans for specific
purposes; and green infrastructure with gray infrastructure. It envisions
green infrastructure as a three-dimensional “envelope” that surrounds,
connects, and infuses buildings, streets, utilities, and the like. As such it
is not separate from gray infrastructure but forms the ground on which
it exists. In other words, there is no fixed boundary between the two. The
erasure of boundaries compels a holistic and interdisciplinary approach
to the planning and design of infrastructure.
KEY CONCEPTS
This report is intended for planners, landscape architects, architects, civil
engineers, scientists, and others interested in the spatial structure, func-
tions, and values (environmental, economic, and social) of natural and
built landscapes. In traditional practice, these professionals have tended to
operate independently of one another. The concept of landscape as green
infrastructure provides a potent platform for integrating the work of physical
designers, policy planners, and others and leveraging this collaboration to
achieve larger societal goals.
▲
Completed in 2006, the Sidwell Friends Middle School expansion in Washington, D.C.,
involved renovating a 55-year old, 33,500-square-foot building and constructing a
39,000-square-foot addition. Integrated water management tied to the school’s environmen-
tal ethic and curriculum was central to the project design. Green roofs are used to retain
and filter stormwater, and a wetland garden is used to treat wastewater before recycling
it as graywater for flushing the school toilets. The system requires holding and a sewage
separator tank powered by rooftop photovoltaic panels—a clear integration of gray and
green infrastructures. Students grow vegetables and herbs for the kitchen on the green
roofs. The site design includes a pond, rain garden, and filters and swales to absorb and
purify stormwater runoff (Figure 2.5). Other features include bicycle storage and showers,
underground parking, and native plantings.
INTEGRATING GREEN WITH GRAY INFRASTRUCTURE: AN EXAMPLE
▲
Figure 2.5. Sidwell Friends
Middle School garden,
Washington, D.C.
Andropogon

16. 12 Green Infrastructure: A Landscape Approach
A related concept is ecosystem services (i.e., the benefits that natural
ecosystems provide for people). These services can be broken down into
provisioning services (e.g., food and water production); regulating services
(e.g., improved air and water quality, carbon sequestration); supporting
services (e.g., nutrient cycling, crop pollination); and cultural services (e.g.,
recreation, community bonding, and spiritual inspiration). Chapter 3 expli-
cates an emerging practice model designed to promote an integrated process
for making green infrastructure a reality. Several overarching concepts thread
through it, including
• the importance of green infrastructure to the “triple bottom line” of sus-
tainability;
• the contributions green infrastructure can make to public health, broadly
conceived; and
• the performance of green infrastructure as a system, interacting with
other systems in ways that shape and connect the natural and built
environments.
Sustainability: Realizing the Multiple Benefits of Green Infrastructure
Central to the concept of green infrastructure is that it provides a wide suite
of benefits. The three “Es” of sustainability (environment, economy, and
equity)—also referred to as the triple bottom line (people, prosperity, and
planet)—offer a useful framework for characterizing these benefits.
Environment
• Green infrastructure can absorb stormwater, reducing runoff and associ-
ated impacts such as flooding and erosion.
• It can improve environmental quality by removing harmful pollutants
from the air and water.
• It can moderate the local climate and lessens the urban heat island effect,
contributing to energy conservation.
• It can preserve and restore natural ecosystems and provide habitats for
native fauna and flora.
• It can mitigate climate change by reducing fossil fuel emissions from
vehicles, lessening energy consumption by buildings, and sequestering
and storing carbon.
Economy
• Green infrastructure can create job and business opportunities in fields
such as landscape management, recreation, and tourism.
• Studies have shown that it can stimulate retail sales and other economic
activity in local business districts (Wolf 1998 and 1999).
• It can increase property values (Neelay 1988; Economy League of Greater
Philadelphia 2010).
• It can attract visitors, residents, and businesses to a community (Campos
2009).
• It can reduce energy, healthcare, and gray infrastructure costs, making
more funds available for other purposes (Heisler 1986; Simpson and
McPherson 1996; Economy League of Greater Philadelphia 2010).

17. Chapter 2. Landscape Planning, Design, and Green Infrastructure 13
Community
• Green infrastructure can promote healthy lifestyles by providing outdoor
recreation opportunities and enabling people to walk or bike as part of
their daily routines.
• It can improve environmental conditions (e.g., air and water quality) and
their effects on public health.
• It can promote environmental justice, equity, and access for underserved
populations.
• It can provide places for people to gather, socialize, and build community
spirit.
• It can improve the aesthetic quality of urban and suburban development.
• It can provide opportunities for public art and expression of cultural values.
• It can connect people to nature. Studies have shown that better health
outcomes, improved educational performance, and reduced violence can
be among the resulting benefits (Ulrich 1984; Kaplan 1995; Berman et al.
2008; Kuo and Sullivan 1996, 2001a, and 2001b).
• It can yield locally produced resources (food, fiber, and water).
Akey question for planners and designers is: How can we measure these
benefits to demonstrate the value green infrastructure brings to society?
Indicators are quantitative or qualitative measurement tools that track prog-
ress toward goals and objectives. They are useful in characterizing complex
system changes over time in relatively simple terms. Early indicator systems
were developed largely to address human impacts on natural ecosystems, but
their scope has broadened to encompass other dimensions of sustainability,
often structured around the triple bottom line. Many of the above benefits
lend themselves to quantitative measurement, for example:
• Environmental Indicators: stormwater volume reduction, harmful pol-
lutants removed from the air, tree canopy coverage, carbon storage and
sequestration, etc.
• Economic Indicators: jobs created, property values increased, reductions in
building energy use, etc.
• Social (Community) Indicators: parks and open space access (typically
measured in terms of walking distance to the nearest resource), parks and
open space equity (typically measured in terms of distribution relative to
demographics), public health outcomes, etc.
Other benefits, such as improved aesthetic quality, support of public art,
and facilitation of cultural expression, are harder to measure, though they are
central to the practice of landscape architects and other design professionals.
Thus, an important challenge is to develop meaningful ways to define the
qualitative benefits provided by landscape as green infrastructure.
Public Health: Expanding the Scope of Green Infrastructure
Public health is an overarching concern that cuts across the triple bottom line
of sustainability. It has become an increasingly important issue for society as
health-care costs have escalated and awareness has grown of the broader im-
pacts of environment, lifestyle, and community conditions on health. Marya
Trees are arguably the largest structural
component of green infrastructure. Their
habitats range from naturally occurring
forests and managed timber stands to the
physical fabric of suburban and urban
communities, where they are planted or
regenerate in private yards and vacant
lots, on institutional campuses, along
streets, in parks and preserves, and
elsewhere. The National Urban and
Community Forestry Advisory Council
(NUCFAC) defines urban forestry as “the
art, science, and technology of managing
trees and forest resources in and around
urban community ecosystems for the
physiological, sociological, economic, and
aesthetic benefits trees provide society”
(NUCFAC 2004).
Schwab (2009) describes the environ-
mental, economic, and social benefits of
the urban forest, defining general and
design principles, and presenting case
studies illustrating how an effective urban
forestry program can be part of a “new
planning agenda.” That report empha-
sizes the importance of valuing the urban
forest as an investment that makes sense
from a triple-bottom-line perspective.
One valuable tool in this area is i-
Tree, a suite of free software programs
developed by the U.S. Forest Service with
cooperating partners. I-Tree can be used
by communities of all sizes to inventory,
evaluate, and quantify the benefits of their
urban forest resources (www.itreetools.
org). I-Tree uses field data from complete
inventories or randomly located plots
to calculate the dollar value of benefits
provided by a community’s urban for-
est, such as pollution removal, carbon
storage and sequestration, and structural
(replacement) value.
▲
THE URBAN FOREST: A KEY
COMPONENT OF THE URBAN
LANDSCAPE AND GREEN
INFRASTRUCTURE
▲

18. 14 Green Infrastructure: A Landscape Approach
Morris (2006) refers to the “social”—as opposed to the “medical”—model
of health, under which public health addresses the health of the community
as a whole, rather than focusing on symptoms and diseases suffered by in-
dividuals. The health of a community is inextricably linked to the health of
its environment as reflected in the landscape, and green infrastructure can
bring important public health benefits. Examples of these benefits include:
• Green infrastructure can improve environmental conditions such as air
and water quality and their associated impacts on human health (exposure
to hazardous substances, asthma, etc.).
• It can encourage walking, biking, and other forms of outdoor activity.1
• It can improve health by bringing people into contact with nature. Richard
Louv (2011) proposes a “Natural Health Care System” to capitalize on the
restorative effects of such experiences on physical and mental health. For
example, many health care professionals are issuing “park” or “nature”
prescriptions for their patients to exercise outdoors in parks or on trails.
Another example is the Medical Mile greenway trail in downtown Little
Rock, Arkansas. Created through a collaboration among parks, recreation,
and public health organizations, it is both a walking / biking trail and an
outdoor “health museum” designed to encourage people to make healthy
living choices.
• It can provide a safer environment for outdoor activity through design,
thus counterbalancing crime, traffic, and other deterrents.
• It can improve conditions in poor and marginalized communities that
too often bear a disproportionate burden from environmental and health
hazards (thus addressing the equity component of the three “Es”). Green
infrastructure can provide a range of health benefits for the residents of
such communities, including improved water quality, reduced air pollu-
tion, increased opportunities for physical exercise, and access to locally
grown food (Dunn 2010).
Green Infrastructure and Systems Thinking
Green infrastructure lends itself to an integrated, systems-thinking approach,
one that overcomes the limitations of more specialized or “silo” methods of
problem-solving. Whereas traditional, mechanistic analysis dissects a system
into individual pieces, systems analysis focuses on how the pieces interact to
produce the behavior of a system (Aronson 1996–1998).2
Aparticular system
can, in turn, be both influenced by the behavior of smaller subsystems and
nested within a larger system (a concept referred to as “systems hierarchy”).
From this perspective, systems defined by separate structures, functions,
and processes intersect in the landscape, working together to determine its
overall behavior as green infrastructure.
But how does such an approach apply in practice and what are its implica-
tions for planners and designers? Recognizing the boundary of the system
in question—the sphere of influence of a specific problem—is the first step
in a systems-thinking approach. Next, tracing connections to other systems
inevitably widens the context of the problem. It is this focus on interactions
that defines a systems approach.
To delve further into the topic, it is useful to understand the basic char-
acteristics of systems. Noted scientist, author, and systems analyst Donella
Meadows defined a system as “A set of elements or parts that is coherently
organized or interconnected in a pattern or structure that produces a char-
acteristic set of behaviors, often classified as its ‘function’ or ‘purpose’”

19. Chapter 2. Landscape Planning, Design, and Green Infrastructure 15
(Meadows 2008, 188). Applying this definition, green infrastructure is a
system that comprises constituent parts (e.g., trees, soil, and constructed
infrastructure); that is organized into a pattern (the landscape); and that
performs functions (e.g., stormwater management and the removal of air
and water pollutants) that have a purpose (the benefits described above).
Moreover, green infrastructure is part of a hierarchy: it incorporates multiple
subsystems (e.g., hydrology, vegetation, and movement) and in turn is a sub-
system within a larger system (e.g., region, city, or neighborhood), where it
interacts with other systems (e.g., transportation, economy, and governance).
The following are additional attributes of systems:
• Interconnections are relationships that hold the parts of a system together.
Examples include flows of resources (e.g., water or energy); flows of infor-
mation (e.g., the communication of knowledge); and interactions among
functional subsystems (e.g., intermodal connections among forms of
transportation such as walking, biking, driving, and transit).
• Astock is the material or information that has accumulated over time from
flows through the system (e.g., the biomass within a mature forest).
• Afeedback loop is a circular (as opposed to linear) pathway formed by an effect
returning to its cause and generating either more or less of the same effect.
A balancing feedback loop tends to counteract or resist any small change in
system behavior (e.g., by keeping the system’s stock within a stable range,
thus maintaining its equilibrium over time).Areinforcing feedback loop tends
to enhance or augment any small change in system behavior in a positive or
negative direction (e.g., a disturbance that causes the system to cross a critical
“threshold” beyond which it is unable to return to its previous condition).
• A leverage point occurs when a targeted intervention results in a significant
change in the behavior of the system. For green infrastructure, this implies
that a solution that addresses multiple problems and “leverages” improve-
ment throughout a system can be more effective than one dealing with a
problem in isolation (e.g., maintaining or restoring the natural hydrologic
processes of a river and floodplain system rather than piecemeal construc-
tion of flood protection devices).
• Resilience is the ability of a system to recover from or adapt to disturbance
or change. (See Walker and Salt 2006.) First developed by ecologists to help
understand the dynamics of natural ecosystems, this concept has broad
implications for planning practice. For example, a city with a diverse eco-
nomic base is less vulnerable to a sudden economic downturn than one that
relies on a single large employer or industry cluster, just as a diverse plant
community is more resistant to insects and disease than a monoculture.
Figure 2.6 conceptualizes how green infrastructure operates as part of a hi-
erarchy of nested systems, each of which contains stocks of assets held together
by interconnections (flows and interactions between systems). In this diagram,
green and gray infrastructure are shown as subsystems that together make
up the urban landscape. Landscape is a system that bridges multiple levels
of scale across higher-level systems: environment, community, and economy.
Flows of resources (e.g., energy, materials, and information) are drawn
from the higher-level systems into interactions that generate the various
stocks of assets that make up the landscape (green infrastructure compo-
nents such as trees and rain gardens; gray infrastructure components such
as buildings and streets). While for diagrammatic purposes green and gray
infrastructure are shown as separate, interlocking systems, in reality they
can overlap in design elements such as green buildings and green streets.

20. 16 Green Infrastructure: A Landscape Approach
Figure 2.6 shows the
generation of green and
gray infrastructure as par-
allel processes. Systems
at similar (parallel) levels
will often compete for
limited resources (e.g.,
funding from the eco-
nomic system), but coop-
eration is also possible.
Systems thinking can help
identify opportunities for
cooperation (i.e., sharing
of resources) rather than
competition among paral-
lel systems.
The green and gray in-
frastructure assets in the
urban landscape produce
feedback loops that have
positiveornegativeimpacts
on higher level systems.
Public health is shown as
a leverage point that can
yield triple-bottom-line
Figure 2.6. Green and gray
infrastructure are subsystems
that together make up the urban
landscape.
David Witham, WRT
improvement in the community,
economy, and environment systems.
This underscores the potential of
connecting green infrastructure to
public health.
Application of the three key concepts—the “triple
bottom line” of sustainability, the connection to public
health, and systems thinking—can enrich the practice
of green infrastructure. Chapter 3 further explores
how they can be used to inform the work of urban planners, landscape
architects, engineers, and others involved in planning and design of green
infrastructure.
ENDNOTES
1. Frank, Engelke, and Schmid (2003) differentiate between “recreational” and “utilitarian”
exercise: “Recreational forms of exercise are those undertaken for discretionary reasons
on someone’s leisure time…. Utilitarian forms of physical activity are those that are
worked into one’s daily habits” (56–88). They hold that utilitarian physical activity (e.g.,
walking or biking to work or to shop) is likely to more significantly affect a person’s
health than recreational activity.
2. The biologist Ludwig Von Bertalanffy, a seminal figure in the development of systems
thinking and author of General System Theory (1969), referred to this paradigm as “the
whole is greater than the sum of its parts.”

21. 17
CHAPTER 3
Green Infrastructure in Practice
▲
The practice of green infrastructure falls under the purview of vari-
ous professions, including urban planning, landscape architecture,
civil engineering, parks and recreation, and architecture. To suc-
cessfully create green infrastructure at the landscape scale, these
professions must transcend conventional “silo” modes of thinking
and instead pursue an integrated approach to planning, design, and
implementation. This chapter explores how the concepts introduced
in Chapters 1 and 2 can be incorporated into planning and landscape
architecture practice to realize the triple-bottom-line potential of
green infrastructure.

22. 18 Green Infrastructure: A Landscape Approach
While the landscape approach integrates green and gray infrastructures
across scales from site design to regional planning, conventional public- and
private-sector organizational structures do not lend themselves to this holistic
approach. In the public sector, planners address infrastructure to varying
degrees through their core functions of long-range planning at the district,
citywide, and regional scales; codification of zoning and development regula-
tions; and review of current development applications for conformance with
those regulations. Meanwhile, engineers usually housed in a separate depart-
ment such as public works or utilities design hard infrastructure systems
for transportation, utilities, and stormwater, and they review development
drawings for compliance with engineering standards. Landscape architects
most often work in a parks and recreation department, where they design
parks, streetscapes, and other landscape elements. Because they have differ-
ent training, typically work in separate departments with singular missions,
and deal with dissimilar types and scales of projects, opportunities for these
professionals to work together to achieve broader goals are often limited.
In the private sector, consulting firms typically have core specialties such
as planning, landscape architecture, engineering, or architecture. Where
multiple disciplines are housed in one firm, or when firms with different
specialties form teams to pursue project opportunities, the opportunity for
collaboration across disciplines is greater. However, similar barriers to those
encountered in the public sector (different professional training, project types
and scales, etc.) make a truly integrated approach to planning and design
more difficult. Some of the most successful examples of disciplinary integra-
tion have come when an agency specifies in a request for proposals (RFP)
or a design competition for a project such as a park master plan, corridor /
streetscape improvement, or revitalization plan that it seeks to harness the
triple-bottom-line outcomes of a green infrastructure approach.
So what, specifically, can planners do to promote green infrastructure?
Internally within their organization (e.g., a municipality or private consult-
ing firm), they can build connections across different types of programs and
projects (e.g., from comprehensive planning goals and policies to site-level
design), with other departments (public works, transportation, watersheds,
etc.), and with other professionals (engineers, landscape architects, architects,
etc.). They can also collaborate with outside partners that deal with issues
related to green infrastructure, such as sewer and water authorities charged
with addressing Clean Water Act mandates, regional land-conservation
organizations, and park districts or agencies. The key is to find common
interests across disciplinary and organizational boundaries to make green
infrastructure a vital part of the fabric of our communities and landscapes.
This chapter defines a set of unifying principles intended to accomplish this.
It indicates how green infrastructure can be woven into the established mis-
sions, services, and methods of planning and other professions.
PLANNING AND DESIGN PRINCIPLES
Six principles inform the planning and design of green infrastructure across
different disciplines and scales of professional practice:
1. Multifunctionality
2. Connectivity
3. Habitability
4. Resiliency
5. Identity
6. Return on investment
While this report primarily addresses the
workofplannersandlandscapearchitects,
civil engineers have an important role to
play in advancing green infrastructure
solutions through the design of storm-
water and other infrastructure systems.
The Zofnass Program for Sustainable
Infrastructure at the Harvard Graduate
School of Design and the Institute for
Sustainable Infrastructure (founded by
the American Society of Civil Engineers,
the American Council of Engineering
Companies, and the American Public
Works Association) have taken an im-
portant step in this direction by de-
veloping the Envision Rating System.
Envision provides a holistic framework
for evaluating and rating the community,
environmental, and societal impacts and
benefits of transportation, water supply,
wastewater treatment, and other types of
civil infrastructure projects. Credits used
to develop numeric ratings of projects are
grouped into five categories:
• Quality of Life (benefits to and impacts
on communities affected by the project)
• Leadership (communication and col-
laboration in project development)
• Resource Allocation (quantity, source,
and characteristics of materials and
other resources used in project con-
struction and operations)
• Natural World (impacts on natural
systems)
• Climate and Risk (resiliency vis-à-vis
short-term hazards such as flooding
and long-term changes such as sea
level rise)
Examples of specific credits relevant to
green infrastructure include encouraging
alternative modes of transportation (i.e.,
trails, bikeways, transit, etc.—Quality
of Life), managing stormwater (Natural
World), and managing heat island effects
(Climate and Risk). See www.asce.org
/Sustainability/ISI-Rating-System.
▲ GREEN INFRASTRUCTURE
AND THE PROFESSIONS OF
PLANNING AND LANDSCAPE
ARCHITECTURE
▲

23. Chapter 3. Green Infrastructure in Practice 19
Multifunctionality
This principle builds on the concept of the triple bottom line—the environ-
mental, economic, and community benefits provided by green infrastructure.
Also called ecosystem services, these benefits derive from the multiple and
overlapping functions provided across the different systems—hydrology,
transportation, energy, economy, and so on—that can intersect in green infra-
structure. The multifunctionality principle calls on planners and designers to
maximize value for the communities they serve by using green infrastructure
to achieve seemingly disparate goals such as flood control, reduced depen-
dence on imported energy, and improved public-health outcomes.
Spanning more than 15 years of plan-
ning and design, the Trinity River
Corridor Project seeks to transform
the 2,300-acre floodway of the Trinity
River near downtown Dallas into
a sustainable, city-building green
infrastructure catalyst (Figure 3.1).
The project is guided by five interre-
lated and overlapping improvement
strands—flood control, environ-
ment, recreation, transportation,
and economic development—woven
into the overriding goal of maximiz-
ing the value of new infrastructure.
The project will achieve this goal by
modifying existing levees to achieve
greater flood protection and reliev-
ing downtown traffic congestion through construction of a new toll road, while inducing
the level of green amenity and environmental health necessary to spur a new generation
of sustainable development in the city’s core. The linkage between green amenity and
infrastructure has been established, for example, by sizing and configuring on-site “bor-
row areas” (from which fill materials needed for the expanded levees and toll road are
extracted) into recreational lakes laced with marshlands and dotted with “floating wet-
lands” (rings of suspended aquatic vegetation)—features that provide water cleansing,
aquatic habitat, and recreational value. In this and other ways the floodway will emerge
as a massive public work of green infrastructure, changing the function and identity of
a heretofore little-seen and even less-used public resource. (See the related case study of
the North Texas region in Chapter 4.)
▲
THE MULTIFUNCTIONALITY PRINCIPLE AT WORK: TRINITY RIVER CORRIDOR
PROJECT, DALLAS
▲
Figure 3.1. The Trinity River
Corridor Project, Dallas
WRT
Connectivity
This principle means that green infrastructure is most effective in provid-
ing services and benefits when it is part of a physically connected system
across the landscape (e.g., a natural reserve or a park). For example, a natural
reserve that is connected to others by a corridor of native vegetation (e.g.,
along a river or stream) is more valuable (all other factors being equal) than
one surrounded by urban development because it allows for wildlife move-
ment between different habitat areas. Similarly, a park that is connected to
other parks via a regional hiking or biking trail serves more people than one
surrounded by a local residential neighborhood.

24. 20 Green Infrastructure: A Landscape Approach
To create a connected green infrastructure system at the landscape scale,
planners and designers should establish physical and functional linkages
across urban, suburban, and rural landscapes and across scales to connect
site, neighborhood, city, and region. For example, vegetated corridors along
major watercourses can connect rural, suburban, and urban areas within a
region, providing multiple benefits such as wildlife habitat, recreation, and
management of water quantity and quality. The form of this corridor may
vary, taking shape as a native riparian woodland in a rural (agricultural)
context, more actively managed landscape plantings in a suburban context,
or intensively designed landscape treatments that function as movement
corridors and gathering spaces in an urban context. Green boulevards and
streets that incorporate native or indigenous plantings to benefit wildlife,
natural stormwater management features, and safe accommodations for pe-
destrians and bicyclists can serve as green infrastructure connections in more
densely developed suburban and urban areas. In creating connected green
infrastructure systems, planners and designers can draw on basic concepts
of landscape ecology (patch, corridor, edge, and matrix as the large-scale
structural components of landscapes).
Habitability
The habitability principle positions green infrastructure as visible space
that provides outdoor habitat for people, flora, and fauna. The mission of
the public health profession—to foster conditions in which people can be
healthy—is central to the idea of habitable green infrastructure. Examples of
green infrastructure planning and design outcomes that advance this prin-
ciple include improved air and water quality (resulting in improved health
of humans and ecosystems), increased opportunity for outdoor recreation
and exercise, and restoration of native habitats.
Resiliency
Defined as the ability to recover from or adapt to disturbance and change,
resiliency is particularly relevant in a time when natural and human eco-
systems are experiencing accelerating change and instability, ranging from
higher energy prices to economic shocks to the projected effects of climate
change. Examples of how green infrastructure can increase community
resiliency across scales include:
• Trees and green roofs can counteract the urban heat island effect at the
city scale and reduce the cooling needs of individual buildings.
• A community can reduce its vulnerability to storms and the cost of pro-
tective gray infrastructure by maintaining the natural flood absorption
capacity of coastal or riparian wetlands and floodplain areas.
• Tree plantings, green and “blue” roofs, permeable pavement, rain gardens,
and other techniques that absorb rainfall on-site can reduce the impacts
of urban runoff during storms (e.g., overburdened storm sewers, street
flooding, and combined sanitary / storm sewer overflows into rivers and
streams).1
Green infrastructure can increase community resiliency over short and
long timeframes (e.g., reduced damage and faster recovery from natural
disasters, increased ability to adapt to climate change). One study concluded
that green infrastructure treatments (increased tree cover, green roofs, etc.)
could significantly reduce the stormwater runoff and surface temperature
increases projected in the 2080s as a result of greenhouse gas emissions (Gill
et al. 2007).
LANDSCAPE ECOLOGY
TERMS, CONNECTIVITY, AND
GREEN INFRASTRUCTURE
Commonly referred to as a “hub” or
“node” by planners and designers of
green infrastructure systems, a “patch”
is defined by landscape ecologists as a
discrete area of the landscape that differs
from its surroundings (e.g., a park or
natural reserve). A “corridor” is a linear
element that links natural habitat patches.
Riparian habitat along a river or stream
is a common example, while roadways
are important corridors in urban and
suburban landscapes. An “edge” is the
transition area between different land-
scape elements (e.g., patches and corri-
dors). Finally, the “matrix” is the overall
landscape structure or pattern within
which patches, corridors, and edges are
embedded. While green infrastructure
network design typically focuses on
creating hubs and connecting corridors
(often called links), the role of the matrix
in fostering connectivity—e.g., an urban
or suburban community with a healthy
urban forest—should not be overlooked.
From a systems perspective, connectivity
encompasses both natural ecological func-
tions such as providing habitat routes for
wildlife and human ones such as promot-
ing social equity by connecting people to
green infrastructure.
One good working definition of land-
scape ecology overall is: “The study of
native landscape structure, function, and
change at the scale of the entire landscape,
as well as the application of the results
to the design and management of both
natural and human dominated areas”
(Benedict and McMahon 2006, 283).
▲
▲

25. Chapter 3. Green Infrastructure in Practice 21
Identity
Design of landscape elements to
create a perceptible identity and
sense of place is a central moti-
vation of landscape architects.
Planners often use the term “com-
munity character” to express the
special and valued attributes that
make a place desirable to live in
or visit. The identity principle
addresses the potential of green
infrastructure to contribute to the
visual definition of a place. A tree,
for example, can act as a carbon sink
and, through shading, contribute
to energy conservation, both of
which functions can be quantified.
But what kind of tree is it and in
what location? Is it appropriate for
the native terrain, vegetation, and
climate? What added recreational
or spiritual benefit does it provide?
Does it have any aesthetic or cultur-
ally significant effect?
In this context, the integration
of art within the public sphere
becomes a relevant consideration.
In recent decades Ecological Art
or “Eco-Art” has emerged as a
distinctive genre within the field of
public art.2
One early practitioner
is Seattle artist Buster Simpson,
whose work “Beckoning Cistern”
captures roof stormwater from
a loft building and directs it via
inventive scuppers and storage
tanks to streetside rain gardens.
This project fully captures the
potential of green infrastructure to
engender a unique sense of place.
Thinking across scales, could a
recurring motif expressed through
stormwater or other forms of green
infrastructure help visually define
a neighborhood, city, or region?
WATERSHED SCULPTURE: PUBLIC ART AS GREEN INFRASTRUCTURE
Artists Daniel McCormick and Mary O’Brien describe their work thus: “We want our
sculptures to have a part in influencing the ecological balance of compromised environ-
ments. We are compelled by the idea of using sculpture in a way that will allow the
damaged areas of a watershed to reestablish themselves. As it has evolved, our art has
become focused on strategically congregating sculptural components made from riparian
materials back into the watershed system. They are are intended to give advantage to
the natural system, and after a period of time, as the restoration process is established,
the artists’ presence shall no longer be felt” (http://danielmccormick.blogspot.com).
A recent example of McCormick and O’Brien’s watershed sculpture is in downtown
Charlotte, North Carolina. Constructed with volunteer help out of branches and other
natural materials, this installation is located on Little Sugar Creek near the Charlotte
Nature Museum in Freedom Park. The Little Sugar Creek greenway is part of the Carolina
Thread Trail, a regional network of greenways and trails that extends through 15 counties
in North Carolina and South Carolina. Under the leadership of Dr. Reed Perkins, students
at Queens University of Charlotte are conducting a study of the effects of the sculpture
on the water quality of Little Sugar Creek.
Figure 3.2. Daniel McCormick’s “Intersections” sculptures, sited
along the Carolina Thread Trail in Freedom Park, Charlotte, North
Carolina, are both art and public infrastructure. The sculptures
help capture the runoff from bordering streets by spreading and
sinking it and preventing an excess of silt and surface pollution
from entering Little Sugar Creek, the city’s largest urban creek.
Daniel McCormick
▲
▲

26. 22 Green Infrastructure: A Landscape Approach
Return on Investment
In a time of scarce financial resources, this principle calls on plan-
ners and designers to demonstrate how green infrastructure can
reduce costs and yield positive financial outcomes for govern-
ments, institutions, businesses, and citizens. Examples of ways
that green infrastructure can generate monetary value include
increasing land values, providing a catalyst for economic devel-
opment, lessening energy consumption, and reducing gray infra-
structure costs. Planners and designers should use cost-benefit
analyses to justify green infrastructure approaches, to plan and
design green infrastructure components to achieve goals such
as reduced energy use and increased revenue, and to establish
targets and indicators to monitor whether these goals are being
met in implementation.
SCALES OF PLANNING PRACTICE
Planners and designers of the physical environment can apply
the green infrastructure principles to achieve triple-bottom-line
benefits at different scales in different contexts. While important
work has been done at the state level, we focus here on four in-
terrelated scales: regional, local government, subarea / district /
neighborhood, and site.3
• At the regional scale, green infrastructure can help shape the
pattern and form of development to promote outcomes such
as urban revitalization, rural land preservation, reduced costs
of publicly provided infrastructure and services, and increased
opportunities for walking, biking, and transit use.
• At the scale of the local government, planning policy, regula-
tions, and capital investments can be used to incorporate
communitywide green infrastructure systems such as parks
and greenways, a healthy urban forest, and green streets and
boulevards into the physical fabric of existing and new devel-
opment.
• The district, subarea, or neighborhood scale lends itself to use of
green infrastructure features (green streetscapes, community
parks and gathering places, etc.) in master planning and urban
design to achieve local benefits such as enhanced air and water
quality, greater recreational opportunity, an improved business
climate, and increased social interaction and exchange.
• At the site scale, housing or mixed use developments, campuses,
parks and public places, and other project types can incorporate
green infrastructure design interventions such as green storm-
water infrastructure, green roofs, living walls, and so on.
Planners can to help the communities they serve achieve the
triple-bottom-line benefits provided by green infrastructure by
consistently applying the six guiding principles across diverse
scales and project types. Table 3.1 (pp. 24–25) provides illustra-
tive examples of how the principles can be applied in different
contexts.
EXAMPLES OF THE RETURN-ON-
INVESTMENT PRINCIPLE AT WORK
• The triple-bottom-line analysis conducted for
Green City Clean Waters, the Philadelphia Water
Department’s Long-Term Control Plan Update
(Philadelphia 2009), found that green stormwater
infrastructure investments (green streets, green
roofs, pervious pavement, etc.) would yield a $2.2
billion return on $1.01 billion spent over a 40-year
period. Monetary values were calculated for eight
different factors, yielding projected benefits such
as roughly 250 people employed in green jobs, one
million or more additional recreational user-days,
six million fewer kilowatt-hours of electricity and
eight billion fewer BTUs of fuel used annually, and
about 140 fewer heat-related deaths over 40 years.
(Green City Clean Waters is included as a case study
in Chapter 4.)
• According to Economy League of Greater
Philadelphia et al. (2010), protected open space
in southeastern Pennsylvania adds $16.3 billion
to housing property values, generates $240 mil-
lion annually in local property tax revenues, and
generates more than 6,900 jobs and $299 million
in annual earnings. In addition, health-related cost
savings (avoided workers’ compensation costs
and productivity losses) from physical activity on
protected open space total $1.3 billion per year.)
• Many studies have documented the positive eco-
nomic impacts of trails at regional and larger scales.
For example, on the Great Allegheny Passage—
a150-miletrailbetweenPittsburghandCumberland,
Maryland—the “Trail Towns” program aims to
realize the economic potential of the trail, which
has been calculated to generate over $40 million
in annual direct spending by users and $7.5 mil-
lion in annual wages attributed to trail businesses.
Approximately 40 percent of trail users plan an
overnight stay, averaging 30 to 40 miles and $98 in
spending a day (Campos 2009).
• The Trinity River Corridor in Dallas is envisioned
as the catalyst for the potential redevelopment of a
square mile of adjoining lands, mostly older ware-
housing and small-scale industrial uses. The value
of such redevelopment could ultimately reach $8
billion, depending on density, building typologies,
and use—tenfold the projected cost of the corridor’s
green infrastructure improvements. The return on
investment will be compounded by energy savings
and health benefits accruing from denser develop-
ment supported by public transit in close proximity
to the city’s downtown.
▲
▲

27. Chapter 3. Green Infrastructure in Practice 23
Regional Scale
At the scale of the metropolitan region, planning for green infrastructure can
make connections (e.g., regional greenway and trail systems) and address
natural landscape features (e.g., watersheds and ecological zones) across
jurisdictional boundaries. Planners and policy makers can promote green
infrastructure at the regional level by:
• Integrating green infrastructure with regional patterns of growth and
conservation
• Directing investments in regional systems such as transportation, storm-
water drainage, and open space toward green infrastructure
• Facilitating partnerships among public agencies, nonprofit land conserva-
tion organizations, institutions, businesses, and developers who stand to
benefit from green infrastructure solutions
• Leveraging resources for implementation (e.g., by tapping public and
private funding streams for green infrastructure projects and programs)
In the United States, regions are typically defined to include a core city
(or cities) and surrounding suburban and rural communities, with in some
cases a metropolitan planning organization (MPO) or council of govern-
ments serving as a regional planning agency. Formal regional governance
models are generally limited to combined city-county governments (e.g.,
Indianapolis and Marion County, Louisville Metro) and special legislative
entities established to manage land use and protect high-quality resources
within designated areas (e.g., the Lake Tahoe Regional PlanningAgency and
New Jersey Pinelands Commission). While MPOs focus on transportation
GREEN INFRASTRUCTURE AND THE TRANSECT
Under the landscape approach, green infrastructure assumes different typologies and physical characteristics in urban, suburban, and
rural contexts and the transitions among them. This continuum is analogous to the rural-to-urban transect planning model promulgated
by planning firm Duany Plater-Zyberk and Company (DPZ). The Transect consists of six zones of increasing density with associated
design standards: Rural Preserve, Rural Reserve, Sub-Urban, General Urban, Urban Center, and Urban Core (downtown or central
business district) (www.dpz.com/transect.aspx). Using this analogy, green infrastructure in rural contexts corresponds to either the
Rural Preserve (as wilderness) or to the Rural Reserve (as “working lands with conservation value” [Benedict and McMahon 2006]). In
more-developed suburban contexts, green infrastructure takes on forms such as nature preserves surrounded by development, parks
with active recreational facilities, and private gardens. Green infrastructure merges with the built environment in dense urban contexts
(Urban Center and Urban Core), where it is expressed in streetscapes, urban parks and public gathering spaces, green stormwater
infrastructure, and so on.
▲
▲
Figure 3.3. The Transect
Duany Plater-Zyberk and Company

28. MULTIFUNCTIONALITY
CONNECTIVITY
HABITABILITY
RESILIENCY
IDENTITY
RETURN
ON
INVESTMENT
Address
GI’s
contributions
to
regional
goals
(e.g.,
transportation,
economic
development,
water
management)
REGIONAL
GROWTH
/
VISION
PLANS
Integrate
GI
into
land-
use
and
development
patterns
across
jurisidictions
Address
the
importance
of
GI
to
quality
of
life
and
attractiveness
Develop
a
strategy
using
GI
to
mitigate
/
adapt
to
climate
change
Reinforce
identity
(e.g.,
by
incorporating
distinctive
natural
and
cultural
resources
into
the
GI
system)
Use
GI
to
strengthen
the
economy
(e.g.,
business
and
worker
attraction
/
retention,
food
and
fiber
production,
tourism)
FUNCTIONAL
MASTER
PLANS
Address
GI
and
its
benefits
(e.g.,
in
MPO
long-range
transportation
plans)
Develop
a
GI
plan
(network
map,
policies,
implementation
strategies)
Use
GI
to
increase
the
resiliency
of
systems
Incorporate
wayfinding
and
interpretation
into
the
GI
system
Calculate
the
economic
benefits
generated
by
GI
Use
GI
to
improve
air
and
water
quality
R
E
G
I
O
N
COMPREHENSIVE
PLANS
Develop
a
GI
element
linking
to
other
comprehensive
plan
elements
(transportation,
land
use,
etc.)
through
a
systems
approach
Incorporate
a
greenways
/
trail
plan
element
linking
to
adjacent
jurisdictions
Address
the
role
of
GI
in
improving
public
health
(mobility,
recreation,
improved
air
and
water
quality,
etc.)
Consider
how
GI
can
integrate
the
natural
and
built
environments
to
improve
community
character
and
express
community
identity
Include
indicators
tracking
the
monetary
returns
of
GI
in
plan
implementation
and
monitoring
programs
Establish
policies
and
strategies
to
reduce
vulnerability
to
storm
damage
and
flooding
through
GI
FUNCTIONAL
MASTER
PLANS
Consider
GI’s
benefits
in
other
local
government
plans
(transportation,
economic
development,
parks
and
recreation,
etc.)
Develop
an
in-depth
GI
plan
with
strategies
to
develop
a
connected
GI
network
Preserve
and
restore
wildlife
habitat;
connect
people
to
natural
resources
and
outdoor
recreation
opportunities
(e.g.,
through
transportation
linkages)
Incorporate
GI
into
climate
action
plans
Link
GI
to
the
preservation,
interpretation,
and
adaptive
reuse
of
cultural
and
historic
resources
Use
GI
to
reduce
the
costs
of
gray
infrastructure
(e.g.,
stormwater)
DEVELOPMENT
REGULATIONS
AND
CODES
Integrate
regulatory
provisions
(e.g.,
stormwater
/
floodplain
management,
subdivision
control,
tree
protection)
to
leverage
GI’s
benefits
Enact
regulatory
approaches
(e.g.,
requirements
or
incentives
for
open
space
set-asides)
to
encourage
development
of
a
connected
greenway
system
Develop
“healthy
development”
code
provisions
using
GI
to
encourage
less
automobile-dependent
and
more
walkable
development
patterns
Enact
regulatory
provisions
protecting
floodplain
and
riparian
resources;
use
a
stormwater
utility
to
generate
money
for
GI
stormwater
solutions
Develop
tree
and
landscape
ordinances
and
standards
emphasizing
the
preservation
of
native
habitats
and
use
of
native
plant
materials
Identify
and
communicate
GI’s
positive
economic
returns
CAPITAL
IMPROVEMENT
PROGRAMS
/
PROJECTS
Use
GI
to
increase
the
range
of
benefits
provided
by
capital
projects
(e.g.,
stormwater
management,
recreation,
reduced
energy
use)
Incorporate
GI
into
street
improvement
projects
Develop
parks,
trails,
and
sidewalk
networks
to
provide
residents
with
equitable
access
to
outdoor
recreation
Incorporate
stormwater
GI
into
public
capital
improvement
programs
Integrate
public
art
with
GI
in
capital
projects
(parks,
streetscapes,
public
landscapes,
etc.)
Conduct
cost-benefit
analyses
of
proposed
capital
projects
to
determine
GI’s
long-
term
savings
L
O
C
A
L
G
O
V
E
R
N
M
E
N
T

29. MULTIFUNCTIONALITY
CONNECTIVITY
HABITABILITY
RESILIENCY
IDENTITY
RETURN
ON
INVESTMENT
Permit
compatible
uses
yielding
economic
returns
(e.g.,
urban
agriculture,
renewable
energy
generation)
Use
GI
to
improve
return
on
investment
(e.g.,
through
increased
attractiveness
for
tenants,
reduced
energy
use)
DISTRICT
/
OVERLAY
ORDINANCES
Develop
an
ordinance
to
maximize
GI’s
benefits
within
designated
subareas
Connect
GI
networks
through
regulating
plans
and
incentives
Enact
design
standards
to
promote
pedestrian-
friendly
development
and
street
networks
Use
a
GI
ordinance
to
protect
areas
vulnerable
to
natural
hazards
(e.g.,
flooding)
Enact
design
standards
that
use
GI
to
express
distinctive
character
and
sense
of
place
SITE
DEVELOPMENTS
Enact
development
standards
to
leverage
GI’s
functions
and
benefits
Consider
how
on-site
GI
can
link
to
larger
GI
networks
Incorporate
recreational
facilities
and
other
usable
outdoor
spaces
Use
GI
to
meet
stormwater
management
needs
(e.g.,
on-site
bioswales
and
rain
gardens;
off-site
regional,
multifunctional
facilities)
Incorporate
references
to
native
ecosystems
and
indigenous
building
materials
into
designs
Table
3.1.
Incorporating
green
infrastructure
(GI)
into
planning
practice
S
U
B
A
R
E
A S
I
T
E
SUBAREA
/
DISTRICT
PLANS
Address
GI’s
benefits
in
master
planning
and
design
at
the
subarea
scale
Design
detailed
GI
networks
(parks
/
nodes,
streets
/
sidewalks,
trails
/
riparian
corridors,
etc.)
Use
GI
to
improve
environmental
quality,
create
walkable
environments,
and
provide
habitat
for
wildlife
Incorporate
GI
strategies
in
plans
to
reduce
risks
from
flooding
and
storm
damage
Enhance
community
identity
through
GI
(e.g.,
parks
and
community
gathering
places)
Develop
indicators
to
track
the
positive
returns
of
GI
(e.g.,
increased
economic
activity,
improved
public-health
outcomes)

30. 26 Green Infrastructure: A Landscape Approach
planning, since they are conduits for federal funding of transportation proj-
ects and programs, in recent years many have broadened their purviews to
address other regional issues. For example, the Mid-Ohio Regional Planning
Commission, the MPO for the Greater Columbus region, has established a
Center for Energy and Environment that administers programs on topics
such as greenways and water quality, sustainable growth, local foods, and
energy efficiency.
Some regional planning agencies have launched initiatives specifically
focused on green infrastructure. There are two general types of these initia-
tives: comprehensive regional plans (e.g., Vision North Texas; see Chapter 4)
and functional master plans that address specific systems such as transporta-
tion, housing, or natural resources and open space. Examples of functional
planning for green infrastructure at the regional level include:
• The Hudson Valley Regional Council is leading a green infrastructure plan-
ning project to protect and restore watersheds in the Hudson Valley region
of New York State (https://sites.google.com/site/greeninfrastructure
planning).
• In North Carolina, the Land-of-Sky Regional Council’s green infrastruc-
ture initiative establishes “a regional framework for conservation and
development that will strategically guide future growth for Madison,
Buncombe, Henderson, and Transylvania counties while respecting the
integrity of the region’s ecosystems” (www.landofsky.org/planning
/p_linking_lands.html).
• The Richmond and Crater Planning District Commissions (Virginia) part-
neredona“blue-green”infrastructureinitiative,RegionalBlue-GreenInfra-
structure Project: Green Infrastructure Planning Tools for Connected Com-
munities (www.richmondregional.org/planning/green%20infrastructure
.htm).
The federal Sustainable Communities Partnership, which includes the U.S.
Department of Housing and Urban Development (HUD), the Department of
Transportation, and the EPA, has provided a new impetus for regional plan-
ning. In 2010 and 2011, HUD awarded grants to regions across the country
to develop Regional Plans for Sustainable Development. Led by Regional
Consortiums comprising public, private, and nonprofit sector partners,
these plans are intended to integrate and coordinate housing, transporta-
tion, economic development, environmental quality, and land-use decision
making at the regional level.
Local Government Scale
Units of local government have the primary legal authority for planning,
regulation, and public capital investment within their jurisdictions. Local
governmental planning can address green infrastructure by:
• Setting policy direction for decision makers in long-range planning
documents
• Incorporating green infrastructure into capital improvement programs
and projects
• Enacting regulatory requirements and incentives for green infrastructure
(e.g., ordinances protecting sensitive environmental resources or increased
density for subdivisions that maintain valuable open space and greenway
connections)
• Establishing partnerships and leveraging resources for implementation

31. Chapter 3. Green Infrastructure in Practice 27
While the local governmental scale
facilitates direct implementation of green
infrastructure through actions such as capital
improvements and changes to development
regulations, it does not necessarily address
how green infrastructure within a jurisdic-
tion fits into a regional system (e.g., by con-
necting to greenway and trail networks in
adjacent communities).
Local governments can address green
infrastructure through a variety of planning
applications. The comprehensive plan (re-
ferred to as the general plan in California and
master plan in New Jersey) is the primary
policy document of local governments and
as such is the perhaps the best mechanism for
promoting the triple bottom line of sustain-
ability: economic prosperity, environmental
quality, and social equity. Comprehensive
plans are typically organized into functional
elements such as land use, transportation,
housing, and economic development, but a
more integrated approach treats these ele-
ments as interrelated systems rather than as
separate topics (Godschalk and Anderson
2012). Because it connects multiple systems
and functions, green infrastructure is an
obvious candidate to help implement such
an approach. For example, comprehensive
plans can include green infrastructure as a
core element (in place of a more traditional
open space and natural resources element)
and identify connections with land use,
transportation, and other elements in the
plan goals, policies, strategies, and imple-
mentation actions. (On developing a green
infrastructure element in a comprehensive
plan, see the appendix to Schwab 2009.)
Planning for communitywide functions
(systems) such as housing and transporta-
tion is another planning responsibility of
local jurisdictions.Anumber of counties and
municipalities have developed stand-alone
plans that address green infrastructure as a
communitywide system. County plans typi-
cally follow the model of green infrastructure
as a large-scale, predominantly natural
landscape network. Examples include
Kingston-Lenoir County and Lancaster
County, Pennsylvania; Prince George’s
County, Maryland; and Saratoga County,
NewYork. Green infrastructure plans by mu-
nicipalities such as Philadelphia, Lancaster,
Pennsylvania (see Chapter 4), and New York
City typically focus on green stormwater
infrastructure.
GREENSCAPES: LANCASTER COUNTY GREEN
INFRASTRUCTURE PLAN
Located in southeastern Pennsylvania about 40 miles west of Philadelphia,
Lancaster County is renowned for its agricultural landscape and the cultural
heritage of its Plain Sect (Amish and Mennonite) communities (Figure 3.4).
Its 944 square miles encompass 60 municipalities and a population of 519,445
as of 2010. In 2009 the Lancaster County Board of Commissioners adopted
Greenscapes to replace the 1992 Regional Open Space Plan as an official element
of the Lancaster County Comprehensive Plan.
Lancaster County’s rich natural resources have been extensively altered by
agriculture (accounting for approximately 54 percent of the county’s land area) and
residential, commercial, and industrial development (approximately 18 percent).
Greenscapes complements the growth management element of the comprehen-
sive plan, which establishes goals, strategies, and tools for municipalities to use
in managing growth and land preservation in designated urban and rural areas.
Greenscapes defines green infrastructure as “Lancaster County’s essential natural
life support system … a network of natural areas, green spaces, and greenways
Figure 3.4. Lancaster County, Pennsylvania, landscape
WRT
in rural, suburban, and urban areas that sustains ecological functions and values
and provides a broad array of benefits for the people of Lancaster County and the
surrounding region.” The plan describes the basic structural components of the
network using landscape ecology concepts: hubs (core natural habitat areas) and
majorgreenwayconnectorsatthecountywidescale;nodesandlinks(smallersystem
components) at the intermediate to local scale; and the matrix of urban, suburban,
and rural landscapes within which these components are located. It establishes
goals, objectives, and strategies for the green infrastructure system based on four
primary system functions: preservation of exceptional natural resources (e.g.,
rare, threatened, and endangered species habitat); conservation or stewardship
of important natural resources (e.g., forests) and the essential life support services
they provide; restoration of natural resource systems and ecological connections
(e.g., riparian vegetation along stream corridors through agricultural and urban
areas); and recreation and improved community health (e.g., development of a
countywide trail network). Finally, it identifies an action plan with specific tools in
four categories—policy and planning, regulation, capital investment, and educa-
tion and outreach—that the County, municipalities, and private and public-sector
partners can employ to realize the goals, objectives, and strategies.
▲
▲

32. 28 Green Infrastructure: A Landscape Approach
The opportunity to include green infrastructure approaches in other
functional plans should not be overlooked. For example, green stormwater
infrastructure, “complete street” concepts, and trail / greenway systems
can be incorporated into transportation plan goals, objectives, strategies,
and actions.4
The implementation elements of comprehensive and functional plans
should specify actions, priorities, and responsibilities for implementing green
infrastructure approaches. Development regulations and codes can promote
green infrastructure in private development (e.g., stormwater management
ordinances requiring green approaches; green building incentives; and re-
quirements or incentives for open space set-asides and protection of natural
resources). Capital improvement programming and project planning (e.g.,
for parks, trails, green streets, and green stormwater infrastructure) provide
another means for local governments to implement green infrastructure.
Subarea / District / Neighborhood Scale
Similar to the way that a regional plan can set the framework for planning
at the local governmental scale, a communitywide comprehensive plan,
functional plans, and development ordinance can set the framework for
more detailed planning, design, and implementation of green infrastructure
within smaller geographic areas of a jurisdiction. Planning applications at
this scale include subarea or district plans (referred to as specific plans in
California) and district or overlay regulations (e.g., a form-based or regu-
lating code that addresses a defined district or an overlay ordinance that
addresses a specific resource type, such as riparian zones).
Site Scale
Approaches such as green stormwater infrastructure, green roofs and building
treatments, and dedicated open space and recreation areas become physical
reality at the site scale. While landscape architects, engineers, and architects are
the primary designers at this scale, planners set important design parameters
for their work by administering development regulations, standards, and
review of subdivisions, site plans, and planned unit developments.
GREEN INFRASTRUCTURE IN THE PLANNING PROCESS
Landscapearchitects,civilengineers,andalliedprofessionalsimplementgreen
infrastructure through site planning and project design. Planners can play an
equally vital role by integrating green infrastructure concepts and approaches
into all levels of planning, from visioning to plan and policy development to
implementation mechanisms such as regulations and capital improvement
programs. This does not require radically different ways of planning, but it
does mean that planners should stress integrating green with gray and other
conventional approaches; optimizing triple-bottom-line results; and using sys-
tems thinking to create connections and synergies across project types, scales,
and disciplines. The six planning and design principles provide a framework
and direction for applying green infrastructure in planning practice.
Given their responsibilities to the communities and elected officials they
serve, planners have a responsibility to raise awareness of the value of green
infrastructure, which is a term not all laypersons will recognize. Emphasizing
the tangible benefits green infrastructure can provide is key to success-
fully communicating its importance. For example, the Philadelphia Water
Department’s Green City, Clean Waters website includes a page describing
how residents, businesses, schools, and community groups can benefit from
green infrastructure projects and programs (www.phillywatersheds.org/
whats_in_it_for_you). The national success rate of voter referendums for
open space protection indicates broad public understanding of the value of

33. Chapter 3. Green Infrastructure in Practice 29
green infrastructure investments.5
In the current economic climate, where
priorities compete for scarce fiscal resources, the multifunctionality and
return-on-investment principles in particular can be used to justify and build
support for community green infrastructure initiatives.
One place where many municipalities can begin is with stormwater infra-
structure. For municipalities, institutions, and developers, federal, state, and
local regulatory requirements increasingly position green stormwater infra-
structure as a viable and preferable alternative to conventional engineering
solutions. The Federal Water Pollution ControlAmendments of 1972 and 1977
(the Clean Water Act) established a basic structure for regulating pollutant
discharges by “point” sources (e.g., pipes and drains) under the National
Pollutant Discharge Elimination System (NPDES). The Water Quality Act
of 1987 expanded the NPDES permit requirements to apply to “nonpoint”
(dispersed) sources. The requirements were issued in two parts. Phase 1
(1990) requires municipalities of 100,000 or more, industrial dischargers,
and construction sites of at least five acres to obtain NPDES permits. Phase 2
(1999) extends the requirements to municipalities with populations between
50,000 and 100,000 and a density of at least 1,000 persons per square mile,
construction sites of one or more acres, and large property owners such as
hospitals, universities, and school districts.
The Environmental Protection Agency (EPA), which is responsible for
Clean Water Act administration and enforcement, “strongly encourages”
the use of green infrastructure to fulfill NPDES permit requirements and to
address water-quality violations caused by combined sanitary and sewer
overflows (CSO; see the Cleveland and Philadelphia case studies in Chapter
4). The EPA has released a series of policy memos and fact sheets on incor-
porating green infrastructure into NPDES and CSO programs, and in July
2012 it announced the selection of 17 communities in 16 states to receive a
total of $950,000 in technical assistance for projects including code review,
green infrastructure design, and cost-benefit assessments (http://water.epa
.gov/infrastructure/greeninfrastructure/gi-support.cfm).
At the state and local levels, many jurisdictions have promulgated storm-
water regulations that encourage green infrastructure approaches, along
with code requirements protecting natural green infrastructure components
such as wetlands, floodplains, stream buffers, and mature trees. Maryland’s
Stormwater Management Act of 2007, for example, “requires that environ-
mental site design (ESD), through the use of nonstructural best management
practices and other better site design techniques, be implemented to the maxi-
mum extent practicable.” ESD is defined as “using small-scale stormwater
management practices, nonstructural techniques, and better site planning to
mimic natural hydrologic runoff characteristics and minimize the impacts
of land impact on water resources” (an approach commonly referred to as
“low-impact development”).
Abroader approach is also possible, such as in Atlanta, which has enacted
a suite of environmental regulations. Befitting a city that places a high value
on its urban forest as central to its identify and sense of place, Atlanta’s tree
ordinance is one of the strictest of any major American city. Administered
by the Arborist Division of the Department of Planning and Community
Development, the ordinance’s stated purpose is to achieve “no net loss” of
trees. Private property owners are required to obtain permits to remove trees
above a minimum size (six-foot diameter at breast height [dbh] for hardwoods
and12-inchdbhforpines).OtherenvironmentalregulationsinAtlantainclude:
• APostdevelopment Stormwater Management Ordinance that encourages the
use of nonstructural stormwater management and site design practices,
including “the preservation of greenspace and other conservation areas
to the maximum extent practicable.”