The Benefits of Green Infrastructure

Close-up of grass growing in a bioswale or rain garden for catching rainwater runoff.By Kathryn Hebert, PhD

Green Infrastructure initiatives are used to reduce and handle the excess water storms bring in to urban environments, and even help the environment and economy.

Storm runoff is a greater problem in urban areas where pavement and other non-porous surfaces prevent much of it from soaking into the ground. When rains are particularly heavy, erosion and flooding can occur, causing damage to property and other infrastructure. Stormwater is also a major cause of pollution. The runoff can carry trash, bacteria, and other pollutants with it. Traditionally, the infrastructure to move stormwater safely in cities includes pipes for drainage and water treatment systems.

Green infrastructure installations include a variety of methods to better soak up and/or store water. These could include adding more open space and vegetation such as gardens, planter boxes, green roofs, bio retention/infiltration islands, or swales (a shallow sunken channel) with plants and grasses to help absorb water.

The City of Norwalk, Conn., has made it a priority to include environmental sustainability as part of its 10-year Planning of Conservation and Development plan. The Parking Authority has already started to work on these efforts. In South Norwalk, at the Webster Parking Lot, the authority will install green infrastructure after recent torrential rainfalls flooded nearby buildings several times, including the Bow Tie Cinema. The project envisions adding planters and other types of vegetation, including more trees, to help soak up the water in the lot before it goes into the drainage system. The city received an Environmental Protection Agency grant of $250,000 through the Long Island Sound Futures Fund to help finance the initiative. The project is being run by the office of Transportation, Mobility, and Parking and the Department of Public Works.

The green infrastructure will not only help ease flooding of the Webster Lot and make it more pleasant to look at, but will also help keep Long Island Sound clean. Given the close proximity of the lot to the Sound, adding areas to absorb the water in the lot means fewer pollutants will run into the Sound.  Adding green infrastructure to the lot will prevent more than 6 million gallons of stormwater and 12 pounds of nitrogen from flowing into the Sound annually.

Kathryn Hebert, PhD, is director, transportation, mobility, and parking for the City of Norwalk, Conn., and a member of IPMI’s Board of Directors.