Green Infrastructure Toolkit


Models for Starting Pilots

This section presents pilot project models based on three types of green infrastructure practices (green streets/alleys, green roofs, and rain gardens) and applies various considerations to help local governments choose among them. Some green infrastructure practices, such as green streets, require significant public resources and planning and can only be carried out on the government level. Other practices, such as green roofs, can also be implemented through incentivizing private actors by means of grants or subsidies.See footnote 1  This chapter also includes local government examples of each model. Local governments can compare these models along a set of considerations to enable decision making to meet each local government’s particular situation and priorities. These considerations include both the potential benefits that green infrastructure can achieve and the community or administrative considerations that local governments may want to take into account.


Green infrastructure provides many benefits in addition to managing stormwater. In contrast to gray infrastructure, which can take decades to build and therefore many years for any stormwater management benefits to accrue, green infrastructure can be constructed much more quickly and in more areas, and the benefits are available along that shorter timeline. Pilots can demonstrate those benefits quickly and increase support for green infrastructure as well.  The benefits can be categorized into economic, environmental, and social benefits:

Economic: Green infrastructure can provide public and private economic benefits including flooding losses avoided, cost savings, and increased property values.

Environmental:  Green infrastructure not only improves water quality by enhancing stormwater management capacity, it can also reduce urban heat islands, sequester greenhouse gases, and improve air quality.

Social:  Green infrastructure can enhance green and recreational space, create jobs, and improve public health.

Local governments, in choosing pilot models, may also want to consider some other administrative considerations including:

Public Engagement: Green infrastructure practices that are widely accessible to the public can help to foster a general awareness of green infrastructure as an innovative practice. Engagement with the community can be used to better tailor project designs to the needs of residents and decrease the chance of dissatisfaction with the project.See footnote 2 

Public Education: Green infrastructure practices that provide opportunities to educate the public (due to location in the right of way or along pedestrian walkways, for example) can help foster an informed and supportive community.

Coordination: Some green infrastructure practices, such as green streets, require cooperation and coordination among multiple agencies more so than other practices like rain gardens. Collaboration is important to all stages of implementation: planning and design; development and construction; and operations, maintenance and monitoring.

The paragraphs below discuss the relevant benefits and considerations for each of the pilot models, including some examples of those models in practice.

Green Streets and Alleys

Green streets/alleys integrate green elements such as bioswales, bioretention curb extensions, and/or permeable pavement into transportation right-of-ways.See footnote 3  These practices use vegetation and porous surfaces to capture, store, and infiltrate stormwater in order to reduce runoff from transportation infrastructure, filter out pollution, and mitigate the burden on existing gray infrastructure and treatment facilities.

  • Public education: Green streets are highly visible to the public, and therefore create effective opportunities for public education and outreach concerning green infrastructure and stormwater management issues more generally.
  • Coordination: Efficient inter-agency coordination is important for keeping green infrastructure construction costs as low as possible. When coordinated with broader public transportation improvements such as street improvement or redevelopment, green street practices can significantly reduce the cost of stormwater management by preventing the need for additional and costly gray infrastructure.See footnote 4  Because multiple departments may be needed in order to carry out the development or redevelopment of roadways, successful green streets/alleys will require effective interagency collaboration and coordination. For example, Chicago’s Green Alley Program involved city agencies controlling stormwater management, street design, street-lights, maintenance, and budgeting.See footnote 5 

Green Roofs

Green roofs are vegetated systems built on rooftops that capture and filter rain, reducing the amount of stormwater that flows from roofs to the sewer system. Pilot projects focusing on green roofs have been particularly effective in cities such as Washington, D.C., where rooftops constitute a high percentage of the total impervious surface area. In addition to their stormwater management function, green roofs provide many other private and public benefits such as reduced energy costs, reduced noise pollution, improved air quality, and reduced urban heat islands.  Green roof programs can also be used to create green jobs, to provide green recreational space on rooftops, and to facilitate educational opportunities.See footnote 6  Green roof pilots can focus on either private or public property: many communities provide incentives for private property owners to install green roofs, making them more cost-efficient to install than conventional roofs.See footnote 7  Some communities also use green roofs as an opportunity for public education. Seattle published a map with a self-guided tour of over twenty publicly and privately owned green roofs that are open for public viewing.See footnote 8 

Rain Gardens

Rain gardens are gardens that slow, filter, and absorb runoff from rooftops, sidewalks, and streets.See footnote 9  Rain gardens are particularly effective programs to start with because of their relative simplicity, low cost, and wide application. Unlike green street programs that require significant government involvement, rain gardens can be built and maintained by private individuals on private property. Because they are easy to incorporate into a variety of landscaped areas, rain gardens offer local officials flexibility in how and where to install them, and at what scale.See footnote 10  As with other types of green infrastructure, increased community involvement and knowledge of green infrastructure can lead to community support for more and larger-scale projects.


Related Resources

Portland, Oregon Green Streets Program

Portland, Oregon’s Green Streets are streets that use vegetated facilities to manage stormwater runoff. Portland’s Bureau of Environmental Services (BES) Green Street Program is a sustainable stormwater strategy that meets regulatory compliance and resource protection goals by using a natural systems approach to manage stormwater, reduce flows, improve water quality and enhance watershed health.

Climate Change Vulnerability Analysis for the Milwaukee Metropolitan Sewage District

The Milwaukee Metropolitan Sewage District (District) requested this vulnerability analysis report, which assesses how climate change will impact the District’s existing, as well as proposed, infrastructure and services. The analysis aims to provide the District with the information needed to make strategic planning decisions, such as capital investments. The report documents how climate change may increase flood events and combined sewer overflow volume during larger precipitation events, and increase risk of odor and corrosion within wastewater facilities as well as decreased flow in waterways during periods of warm weather and drought. The analysis also examines the susceptibility of woodpiles and wooden docks at the Jones Island water reclamation facility to degradation resulting from the lower water levels of Lake Michigan brought on by climate change.

Portland, Oregon NE Siskiyou Green Street Project Report

In 2003, the Portland Bureau of Environmental Services installed two landscaped stormwater curb extensions designed to capture street stormwater runoff on Siskiyou Street in Portland, Oregon. Essentially disconnecting the street’s runoff from the City’s combined storm/sewer system, the Siskiyou curb extensions manage it on-site using a landscape alternative. The objective was to maximize the capture, treatment, and infiltration of street stormwater runoff, while enhancing the neighborhood and offering improved pedestrian safety.

Chicago Green Alley Handbook

The Chicago Department of Transportation (CDOT) authored the Green Alley Handbook to encourage the use of best management practices (BMPs) in and around Chicago alleyways and to address impacts to the city’s infrastructure likely to result from projected increases in precipitation and temperature. The handbook promotes sustainable alley design and adjacent landscaping practices to help reduce flooding and manage stormwater, reduce urban heat, promote recycling, and conserve energy.  

Washington D.C. Green Roof Program

In 2003, the Chesapeake Bay Foundation initiated a green roof demonstration project funded under the terms of a consent decree negotiated by the D.C. Water and Sewer Authority. The money was used to issue grants for the installation of eight different pilot green roofs that would reduce the cost of each green roof cost to the building owner by up to 20 percent. The pilot roofs served as models that building owners could use for future green roof projects, by providing data on costs, construction methods, performance, and maintenance needs. 

Green City, Clean Waters - City of Philadelphia, Pennsylvania

Green City, Clean Waters is the Philadelphia Water Department's vision for protecting and enhancing local watersheds by managing stormwater with innovative green infrastructure, through its combined sewer overflow control program. The program is pioneering a broad multi-decade investment in green stormwater management practices that reduce sewer overflows to the City’s waterways, and in turn, enhances communities and the overall urban environment.

Natural Resource Defense Council: Rooftops to Rivers II

From the Natural Resource Defense Council (NRDC), Rooftops to Rivers II describes the challenges of managing stormwater, and the benefits and economics of employing green infrastructure to do so. The report explains how population growth, changing landscapes, aging infrastructure, and climate change are placing increasing pressures on stormwater management. Highly detailed case studies are developed for 14 cities that are all leaders in employing green infrastructure solutions to address stormwater challenges. Local, state and national level policy recommendations are offered also.

Seattle Public Utilities - Street Edge Alternatives

In 2001, Seattle Public Utilities completed construction of its Seattle Street Edge Alternatives (SEA Streets) project, in which a single residential block was retrofitted with vegetated swales and rain gardens. SEA Streets was a pilot demonstration project designed to return drainage and vegetation in the area to a natural systems approach - providing community and street level aesthetic benefits, as well as contributing to the management of rainfall with green alternatives to stormwater drainage. 

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