Thursday, July 23, 2009

Green Alleys

The Department of Public Utilities implemented a Green Alley Demonstration Project at two locations, the alley connecting S. 12th and S. 13th streets, between Main and Cary, and the alley connecting 5th and Main streets, between Main and Cary.

The 12th street location is a doglegged alley with an impermeable surface that slopes toward Shockoe Bottom, an area that has experienced severe flooding in the past. The 5th Street alley is relatively flat, although covered with impermeable asphalt that results in a basin effect during even minor rainfall. By using permeable surfacing, rain gardens, cisterns, and other stormwater management techniques, these alleys were transformed into models for adopting green alley design as a standard, citywide practice.

Retrofitting alleys with green techniques has proven effective at solving stormwater runoff problems in urban areas such as Chicago. Alleys are often holding areas for garbage, construction materials and equipment, increasing the amount of pollution collected in stormwater runoff and carried to the James River and Chesapeake Bay.

This exciting project was the first application of green alley stormwater management in a city within the Chesapeake Bay watershed. The alleys were selected for their different physical characteristics and location in high profile areas susceptible to flooding.

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