Kentucky; Introduction to Green Infrastructure

8/3/2019 Kentucky; Introduction to Green Infrastructure

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Chapter7GreenInfrastructure

A.IntroductionGreen infrastructure refers to natural and engineered ecological systems

that act as living infrastructure, integrating natural vegetation and soils into acommunitys infrastructure through a variety of techniques, approaches,technologies, and practices. Green infrastructure is planned and managed primarilyfor stormwater control, but it also provides additional social, economic, andenvironmental benefits. It can be a useful tool for communities that are looking toprotect their natural water resources and stormwater management systems fromthe impacts of development and urbanization. Green infrastructure methods can beimplemented practically anywhere soil and vegetation can be worked into alandscape.

Source:SoutheastWatershedForumFigure 7-1: Bioretention is one typical method used in green infrastructure.


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B.TypesofGreenInfrastructureCommunities may choose from a wide variety of green infrastructure

techniques. The choice of which techniques to employ and where to locate them is

dependent on site specifications and the goals the community wishes to accomplish.

Specific types of green infrastructure include:

1.GreenRoofsGreen roofs are roofs of buildings that are covered with vegetation and soil,

either partially or completely. Green roofs are layered systems, with a waterproof

membrane, drainage mat, root barrier, growing medium, and vegetation.

Evaporation of water occurs due to the exposure of the plants and growing medium

to wind and sun, and the plants transpire moisture into the air. This helps to cool

the roof. It is vital that plants are chosen for the environment in which the roof is

located. It is also important to promote slow to moderate growth of the plants, so

that they are in balance with their root systems during dormant winter periods.Green roofs can aid in stormwater management and can save energy. They are also

aesthetically pleasing.

Figure 7-2: Green Roof Design

Source:LouisvilleMetroDevelopmentCenter


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2.RainGardensRain gardens, also called bioretention basins, are planted topographic

depressions that are designed to absorb rainwater that drains from imperviousareas, such as roofs, parking areas, streets, walkways, and compacted lawn areas.

Rain gardens reduce runoff because the stormwater soaks into the ground insteadof flowing into storm drains and surface waters. This can help decrease erosion,water pollution, and flooding, and can help to recharge groundwater sources. TheRain Garden Network provides a 10step synopsis of how to build a rain garden.This information is available athttp://www.raingardennetwork.com/build.htm.Additionally, Burnsville, Minnesota has implemented a plan to install a rain gardensystem to infiltrate stormwater runoff that serves as an excellent example ofutilizing this type of green infrastructure (City of Burnsville 2006).

Source:SoutheastWatershedForumFigure 7-3: Rain Garden.


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3.PorousandPerviousPavementsPorous and pervious pavements, also called permeable pavements, are

paving methods that allow rainwater to infiltrate through them into the soil below.These pavements can be used for roads, parking lots, and walkways instead of

traditional impervious pavements, which increase flow velocity of stormwaterrunoff. Porous asphalt, concrete, paving stones, and bricks are examples of perviouspavements.

Source:SoutheastWatershedForumFigure 7-4: Pervious Pavement.


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4.VegetatedSwalesVegetated swales, also known as bioswales, are wide, shallow channels that

are covered on the side slopes and bottom by a dense stand of native vegetation.

Vegetated swales are designed to promote infiltration, reduce the flow velocity ofstormwater runoff, and trap particulate pollutants and silt. They can be eithernatural or constructed, and are often used around parking lots so that pollutionfrom automobiles that is picked up in stormwater can be treated before entering thewatershed.

5.PocketWetlandsPocket wetlands receive, retain, and treat stormwater that has drained from

a limited impervious area. Not only do they reduce stormwater runoff, but they alsoprovide for the filtering of pollutants. Additionally, pocket wetlands areaesthetically pleasing and can even serve as a small wildlife habitat. Pocketwetlands do not require as much space as other stormwater treatment, so they canbe very helpful in congested urban areas.

Source:SoutheastWatershedForumFigure 7-5: Vegetated Swale.


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6.PlanterBoxesThere are two types of planter boxes, contained planters and infiltration

planters. Contained planters are planter boxes that are placed over impervioussurfaces. They hold trees, shrubs, and ground cover. Infiltration planters are

containers or structures with open bottoms that contain a layer of gravel, soil, andvegetation. They are designed to allow stormwater runoff to temporarily pool ontop of the soil and then slowly infiltrate into the ground. Stone, concrete, brick,plastic lumber, or wood can all be used to construct infiltration planters. Portland,Oregon provides an excellent example of utilizing planter boxes for stormwatermanagement (City of Portland, 2004, pp. 4960).

7.GreenParkingGreen parking refers to parking lot design that incorporates green

infrastructure instead of only considering purely functional requirements. Green

parking involves managing stormwater onsite, providing generous landscapedareas, planting trees, enhancing pedestrian and cycling infrastructure, and reducingthe urban heat island effect. Toronto has implemented a plan for greening surfaceparking lots (City of Toronto 2007).

Source:RosettaFacklerFigures 7-6 to 7-9: A green parking lot design at a Walmart in Nashville, TN.


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8.RainBarrelsRain barrels, also called rainwater tanks, are water containers that are used

to collect and store rain water. The rainwater is usually collected from rooftops via

rain gutters. Rain barrels help to reduce the amount of untreated stormwater runoff

into wastewater systems and surface waters. The water stored in rain barrels canbe recycled for many uses, including water gardens, washing cars, agriculture, and

home use. They can also simply store stormwater to be released at a future time.

9.DownspoutDisconnectionDownspout disconnection systems redirect stormwater from traditional

collection systems to vegetated areas. By doing so, green infrastructure components

can manage the runoff and stormwater volume is removed from collection systems.

10.CommunityForestryandTreesTrees and forests are essential elements of a communitys green

infrastructure. These include not only public and private forest lands but also

community forests: the canopy of trees in our communities yards, parks, roadsides

and streetscapes, commercial centers, common areas, and public spaces. They

provide many environmental and economic benefits to property owners,

communities, and watersheds. The benefits of trees and community forests to water

resources include:

Tree root networks filter contaminants in soils producing cleanwater.

Trees prevent erosion by trapping soil that would otherwisebecome silt. Silt destroys fish eggs and other aquatic wildlife andmakes rivers and streams shallower, causing more frequent and

more severe flooding. Trees along streams also hold stream banks

in place to protect against flooding.

Trees reduce topsoil erosion, prevent harmful land pollutantscontained in the soil from getting into our waterways, slow down

water runoff, and ensure that our groundwater supplies are

continually being replenished. For every 5% of tree cover added

to a community, stormwater runoff is reduced by approximately

2%.

Studies that have simulated urban forest effects on stormwaterreport annual runoff reductions of 27%.

In one study, a 32foot tall tree intercepting rainfall reducedstormwater runoff by 327 gallons. (Southeast Watershed Forum,

p. 2)

In addition to waterbased benefits, trees and community forests provide air

quality, climate moderation, energy conservation, and wildlife habitat benefits


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(Southeast Watershed Forum, pp. 23). According to USDA Forest Service, trees

and vegetation reduce stormwater discharge by up to 40%, reduce home heating

and cooling costs by up to 30%, increase the value of property by up to 20%, and

reduce particulate airborne pollution by up to 80%. (Stormwater Managers

Resource Center 2006) In particular, the economic benefits are many. These

economic benefits to property owners, businesses, and communities, according tostudies, include:

Trees enhance community economic stability by attractingbusinesses and tourists.

People linger and shop longer along treelined streets. Apartments and offices in wooded areas rent more quickly and

have higher occupancy rates.

Businesses leasing office space in developments with trees findtheir workers are more productive and absenteeism reduced.

Three trees located strategically around your house can cut airconditioning bills in half. On a larger scale, the cooling effects of

trees can save millions of energy dollars. Property values of homes with trees in the landscape are 5% to

20% higher than equivalent properties without trees. (Southeast

Watershed Forum, p. 1)

Moreover, studies show that the benefits of large trees are 4 to 16 times the benefits

of small trees, depending on whether the benefits are analyzed over a short term or

a long term and whether only benefits to the landowner are analyzed or whether

benefits to the entire community are analyzed (Southeast Watershed Forum, p. 3).

Communities can do many different things to establish or protect trees as

green infrastructure. First, communities can establish a tree canopy goal as part of

their comprehensive plan. Studies recommend that healthy cities should seek to

have at least 40% tree coverage, which is an average of 20 large trees per acre, in

order to achieve ecological, economic, and social sustainability (Southeast

Watershed Forum, p. 1). Second, communities should establish a community

forestry program that supports both public and private efforts to provide, maintain,

and manage local tree canopies. Whether or not a part of a community forestry

program, government agencies should landscape public lands and facilities with

watershedsustaining trees and invest in maintaining those trees. Third,

communities can use their codes and ordinances to protect existing trees and

require tree planning and maintenance on development sites. Fourth, communities

can establish watershed reforestation projects that prioritize sites for reforestation

under a comprehensive watershed forest management plan (Stormwater Managers

Resource Center 2006).


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CaseStudyinCommunityForestry:Fayetteville,Arkansas(Source:NALGEPetal.2003,p.21)

A number of communities across the nation are partnering with groups like

American Forests to identify how the green infrastructure of trees can help reducestormwater runoff and nonpoint source pollution, protect the quality of surface andgroundwater, save localities millions of dollars in gray infrastructure costs, andmeet the regulatory mandates of stormwater and TMDL rules. One suchcommunity is the fastgrowing City of Fayetteville, Arkansas, where AmericanForests recently released a study demonstrating the environmental and economicbenefits of maintaining and increasing local tree cover.

In Fayetteville, rapidgrowth and development has ledto an 18 percent decline of

heavy tree canopy in the last 15years. American Forestsrecently conducted an UrbanEcosystems Analysis usingsatellite and aerial imagery,Geographic Information Systemtechnology, scientific research,and the organizationsCITYgreen computer softwareto calculate the benefits treesprovide to Fayettevilles urban

environment. The findingsshow that the City ofFayettevilles existing tree covercurrently reduces stormwaterrunoff by 50 million cubic feetduring a storm event. The studyalso noted that, if the treecanopy in Fayetteville wereincreased from 27 to 40 percent,the environmental benefitswould be significant and the cost

saving benefits of stormwaterreduction alone would be $135million. (NALGEP et al. 2003, p.21)

Source:TonyArnoldFigure 7-10: Forest in Kentucky.


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11.ProtectingRiparianLands,Wetlands,Floodplains,andNativeLandscapesNature has already provided much of the green infrastructure that we need

in the forms of riparian zones (often with trees and other vegetation), wetlands,

floodplains, and native vegetation. Forest, discussed above, and native grasslandsalso are naturally provided green infrastructure. Unfortunately, much of it has beenlost to human landalteration activities and what remains is at risk of alteration ordegradation. Therefore, a critical green infrastructure strategy is to preserve andprotect natures green infrastructure, while also restoring that which has been lost.

12.SpecificExamplesofGreenInfrastructureFeaturesinParticularDevelopmentSettings

The following provides some examples of how these types of greeninfrastructure can be utilized in particular settings (WERF 2007):

Streetscapeandroadwayprojects- Add tree boxes or infiltration gardens to capture street runoff.

Source:LindaPearsallFigures 7-11 and 7-12: Wetland and Riparian Zone.


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- Design medians as infiltration areas.- Use porous pavement for parking lanes.

Commercialareaswithsignificantparking- Drain roofs to gardens, planters, or parking islands and

medians.- Use permeable pavement in lowtraffic areas.- Drain parking to grass buffers and vegetated swales.

Smallinfillbuildingsitesorretrofits- Install a green roof for buildings and parking structures.- Install permeable pavement in courtyards and plazas.- Drain roofs to grass buffers or swales.

Residentialareas- Drain roofs to rain gardens, grass swales, and grass buffers.- Drain driveways, walkways, and patios to adjacent rain

gardens or grass buffers.

- Construct driveways using permeable pavement.Examples of green infrastructure and policies supporting green

infrastructure can be found on the following websites:

Center for Neighborhood Technology, Green Infrastructure,http://greenvalues.cnt.org/greeninfrastructure

State Environmental Resource Center, Green Infrastructure Policy IssuesPackage, http://www.serconline.org/grInfrastructure/index.html

U.S. Environmental Protection Agency, Managing Wet Weather withGreen Infrastructure,

http://cfpub.epa.gov/npdes/home.cfm?program_id=298

Water Environment Research Foundation, Livable Communities,http://www.werf.org/livablecommunities

C.ChoosingGreen:TheBenefitsofGreenInfrastructureGreen infrastructure can provide a variety of environmental, economic, and

social benefits. These benefits can be especially pronounced in developed area

because environmental damage is usually greater and green space more limited in

these locales. The benefits of green infrastructure include:


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1.Greeninfrastructureimproveswaterquality.Green infrastructure reduces the concentration of pollutants in stormwater

runoff. It does so by causing runoff to infiltrate close to its source, thus helping to

prevent pollutants from being transported to surface waters. Additionally, plants

and microbes can naturally filter and breakdown stormwater pollutants ininfiltrated runoff.

2.Greeninfrastructurereducesanddelaysstormwaterrunoffvolumes.Green infrastructure utilizes the natural retention and infiltration

capabilities of vegetation and soils to naturally retain and absorb stormwater, thus

reducing the volume of stormwater runoff, as well as reducing stormwater runoff

peak flows. Green infrastructure also increases the amount of pervious ground

cover, which in turn increases stormwater infiltration rates. This also reduces the

volume of runoff. By reducing runoff volumes and peak flows entering surface

water bodies and wastewater systems, green infrastructure limits the frequency offlooding and system overflow events.

3.Greeninfrastructureimprovesairquality.Green infrastructure contributes to improved air quality. Vegetation and

trees absorb pollutants from the air, thus filtering many airborne pollutants. They

also cool the air, leading to decreased groundlevel ozone pollution.

4.Greeninfrastructureenhanceswatersupplies.Green infrastructure increases natural infiltration, thus improving the rate at

which groundwater aquifers are replenished. Improved groundwater recharge can

enhance private and public drinking water supplies, and can help to maintain

normal base flow rates for streams and rivers. In addition, green infrastructure

techniques that capture and use stormwater help to conserve water supplies.

5.Greeninfrastructurereducesenergydemandsandincreasesenergyefficiency.

The increased amounts of green space and vegetation provided by green

infrastructure in developed areas can reduce energy demands because they mitigate

the urban heat island effect, thus lowering temperatures. This can also lower the

demand for air conditioning energy, thus decreasing power plant emissions. If

incorporated on and around buildings, green infrastructure can help with shade and

insulation, thus decreasing the energy that is needed for heating and cooling.

Additionally, diverting stormwater from wastewater systems reduces the energy

needed to pump and treat the water. All of this reduces energy costs to businesses,

governments, and community residents.


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6.Greeninfrastructureimproveshumanhealth.Green infrastructure can play a vital role in improving human health. A large

number of studies show that green space and vegetation can positively impact

human health, including reduced levels of innercity crime, a stronger sense of

community, and reduced symptoms associated with attention deficit andhyperactivity disorders (U.S. EPA 2009).

7.Greeninfrastructureenhancescommunitiesandneighborhoods.Green infrastructure can improve the aesthetics of a community because of

the increase in trees and plants. It also provides increased access to recreational

space and wildlife habitats, thus improving community livability. Community

cohesiveness can be enhanced by involving residents with the planning,

implementation, and maintenance of green infrastructure sites. Additionally, a

number of studies show that green infrastructure can increase the property values

in the surrounding area (U.S. EPA 2009).

8.Greeninfrastructuremoderatestheimpactsofclimatechange.Green infrastructure can benefit adaptability for a wide range of

circumstances that result from climate change impacts. This adaptability is possible

because green infrastructure can conserve and reuse water, promote groundwater

recharge, and reduce surface water discharges that can cause flooding. Additionally,

the vegetation utilized in green infrastructure can serve as sources of carbon

sequestration, thus capturing carbon dioxide from the atmosphere.

9.Green

infrastructure

saves

money.

Green infrastructure can save capital costs associated with building,

operating, and maintaining traditional forms of infrastructure. The costs of

repairing damage caused by stormwater can also be avoided.

D.ImplementingGreenInfrastructureinProjectsOnce a community has decided that utilizing green infrastructure may be an

option, it must then assess if this is the best option. One method that can be used

when determining whether, or where, to incorporate green infrastructure is value

engineering. This approach allows for a comparison of the costs and values of greeninfrastructure with that of traditional infrastructure. Value engineering enables a

community to consider the relative costs and benefits of the components of a

project, and then suggests where changes may be made to provide more value for

less cost.

The value engineering approach involves the following steps (WERF 2007):


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Identify elements of value or benefit that can be used to measure andcompare project components. Factors that can be considered when

identifying elements of value or benefit are land area requirements

for flood storage and water quality treatment, allowable or desired

runoff volume, onsite water use requirements, groundwater recharge

needs, landscape amenities opportunities, creation of habitat, andrecreation opportunities.

Develop a schematic of the project using traditional forms ofinfrastructure, and estimate the value or benefit provided, along with

capital and life cycle costs.

Develop an alternative schematic of the project using greeninfrastructure, and estimate value and costs of each component.

Compare the two different approaches to identify which provides thebest value. This is not strictly a costbased analysis.

Once it is decided that a green infrastructure approach will be utilized, and

projects begin to be planned, the following principles and practices can help to

ensure that a green infrastructure project succeeds:

Establish an interdisciplinary team at the beginning of the project.This group should include, among others, community leaders, the

project owner, review agencies, engineers, and landscape architects.

Work to ensure that this team remains together through

implementation of the project.

Understand the regulatory and development review environment. Understand which Best Management Practices work best in which

development settings.

Understand the context in which the project will be placed. The typeof project, as well as its aesthetic qualities, should reflect surrounding

land uses and neighborhood character.

Design the project to mimic the natural environment. Design sustainable projects that can be easily maintained (WERF

2007).

E.ImplementingGreenInfrastructureinLocalPoliciesandCodesGreen infrastructure is a matter of public policy, as well as landowner and

developer choices. In general, when a community has determined that green

infrastructure would be beneficial, certain policy recommendations can be used to

encourage the use of green infrastructure:

get development right the first time; incorporate green infrastructure into longterm control plans for

managing combined sewer overflows;


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revise state and local stormwater regulations to encourage greendesign;

establish dedicated funding for stormwater management that rewardsgreen design;

provide incentives for residential and commercial use of greeninfrastructure;

review and revise local development ordinances; preserve existing trees, open space, and stream buffers; encourage and use smart growth; and get the community involved (NRDC 2006, pp. 1315).

More specifically, though, incorporating green infrastructure into wet growth

policies requires attention to local codes and ordinances. Although some of a

communitys green infrastructure will result from public projects (e.g., government

buildings and facilities, landscape design and management along roads and

highways, and wetlands or stream restoration initiatives) or from the management

of public lands (including parks, nature areas, and recreational facilities, wet growthpolicies also include the creation of green infrastructure on private lands.

Community officials and stakeholders should analyze their local codes and

ordinances to determine whether they:

allow green infrastructure as part of new or existing land uses; encourage green infrastructure as part of new or existing land

uses; and

require green infrastructure as part of new or existing land uses.First, a communitys land development codes and ordinances might directly

or indirectly prohibit landowners and developers from using green infrastructure

and therefore need to be changed. Examples might include: 1) minimum lot sizes or

setback requirements that prevent clustering of structures and preservation of

existing natural features of development sites; 2) barriers to shared ownership and

management of swales, wetlands, and other green infrastructure; 3) requirements

that structures connect downspouts directly to the stormwater sewer system; 4)

roof design or structural requirements that do not allow for green roofs; or 5)

parking requirements that prevent green parking lot design, among other

regulatory requirements. These provisions should be analyzed and amended to

allow green infrastructure.

Second, a communitys land development codes and ordinances can actuallyfacilitate decisions by landowners and developers to use green infrastructure.

These might include density bonuses or other development bonuses (e.g., parking

bonuses, height bonuses, streamlined/fasttrack permitting processes) for certain

especially valuable or extensive green infrastructure features of a development

project beyond normal requirements. They might include rebates of or reductions

in stormwater or sewer service or hookup fees for certain green infrastructure

features that minimize runoff. They might include relief from landscaping


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requirements if existing mature trees and other existing natural landscape features

are retained. Local communities should analyze their codes and ordinances for

opportunities to add incentives that encourage green infrastructure.

Third, communities should consider requiring landowners and developers to

use green infrastructure features, especially for new development. Examplesinclude 1) tree preservation ordinances; 2) minimum tree canopy and/or

landscaping requirements; 3) prohibitions on development of wetlands, riparian

buffer zones, natural forests, native grasslands, or similar watershedsupporting

lands; 4) maximum site coverage ratios; and 5) requirements that developers select

from a menu of greeninfrastructure best management practices (BMPs) in

designing and developing sites, among other possible regulatory requirements.

Protecting or requiring green infrastructure by regulation can be necessary, because

developed sites without adequate stormwater management are imposing the costs

and harms of their land uses onto neighbors, other property owners, businesses,

government agencies, taxpayers, and the public. Private property rights, even from

highly libertarian or freemarket perspectives, have never allowed landowners touse their land in ways that harm others or transfer the costs of their land uses to

others (i.e., known by economists as negative externalities), which is what is

happening when developed land has high quantities, velocities, and/or pollution

levels of runoff flow. However, protections of existing green infrastructure and

regulations requiring harmpreventing green infrastructure especially when

landowners can choose among a variety of green infrastructure methods are

cheaper, more efficient, and more effective at preventing harms (and externalized

costs) for all relevant parties than the alternative ways of remedying these harms:

litigation or fines. Regulatory methods and examples are discussed further in

Chapter 12. In addition, Chapter 5 explores how green infrastructure might be

incorporated into low impact development standards.

Sources:

Center for Neighborhood Technology. Green Infrastructure. Available at

http://greenvalues.cnt.org/greeninfrastructure.

City of Burnsville, Minnesota. 2006. Burnsville Stormwater Retrofit Study.

Available athttp://www.ci.burnsville.mn.us/DocumentView.asp?DID=449.

City of Portland, Oregon. 2004. 2004 Stormwater Management Manual, Chapter 2,

Stormwater Management Facility Design. Available at

http://www.portlandonline.com/shared/cfm/image.cfm?id=55791page=49.

City of Toronto. 2007. Design Guidelines for Greening Surface Parking Lots.

Available at


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http://www.toronto.ca/planning/urbdesign/greening_parking_lots.htm#greenguid

elines.

National Association of Local Government Environmental Professionals et al.

(NALGEP et al.). 2003. Smart Growth for Clean Water: Helping Communities

Address the Water Quality Impacts of Sprawl. Available athttp://www.resourcesaver.com/file/toolmanager/CustomO93C337F42157.pdf.

Natural Resources Defense Council (NRDC). 2006. Rooftops to Rivers: Green

Strategies for Controlling Stormwater and Combined Sewer Overflows. Available at

http://www.nrdc.org/water/pollution/rooftops/rooftops.pdf.

Southeast Watershed Forum. The Value of Community Forests.

Stoner, Nancy and Alexandra Dapolito Dunn. 2008. From Rooftops to Rivers:

Green Infrastructure Yields Economic and Environmental Benefits. AmericanPublic Works Association Reporter. February: 15. Available atwww.apwa.net.

Stormwater Managers Resource Center. 2006. Land Conservation Fact Sheet:

Urban Watershed Reforestation.

State Environmental Resource Center. Green Infrastructure Policy Issues Package.

Available athttp://www.serconline.org/grInfrastructure/index.html.

United States Environmental Protection Agency (U.S. EPA). 2009. Managing Wet

Weather with Green Infrastructure. Available at

http://cfpub.epa.gov/npdes/home.cfm?program_id=298.

Water Environment Research Foundation (WERF). 2007. When Does Green

Infrastructure Make Sense. Available at

http://www.werf.org/livablecommunities/pdf/greenpay.pdf.

Water Environment Research Foundation. Livable Communities. Available at

http://www.werf.org/livablecommunities.

Documents

Kentucky; Introduction to Green Infrastructure