WASHINGTON, D.C. — District of Columbia Mayor Vincent C. Gray celebrated completion of the District’s first “green” alleys. The Green Alley Pilot is part of the mayor’s Sustainable DC initiative to make the District the nation’s greenest, healthiest, most livable city. The alley project — a partnership between the District Department of Transportation (DDOT) and the District Department of the Environment (DDOE) — is aimed at reducing the quantity and improving the quality of stormwater runoff within the District’s right-of-way.

“Improving the health of our rivers and streams starts in our neighborhoods with creative solutions like these green alleys,” Gray said.

Many alleys include a significant amount of impervious surface, but most do not have stormwater controls (such as water quality catch basins or grate inlets). To mitigate this, green alleys use sustainable design and Low Impact Development (LID) techniques that reduce the amount of stormwater and pollutants entering the sewer system, streams, and rivers by increasing water filtration and treatment on site.

Three initial Green Alley Project sites are included in DDOT’s pilot program. DDOT constructed its pilot green alleys by replacing gravel, impervious concrete, or asphalt surfaces with permeable concrete. With the first alleys now completed, DDOT is monitoring the three sites to determine the effectiveness and durability of the materials. DDOT will also be constructing a fourth green alley later this summer and has eight additional alley locations in under design. The future projects will use other permeable materials — including asphalt, paver blocks, and grid systems — to capture the stormwater runoff.

This project is funded through a combination of local dollars and funding received from the American Recovery and Reinvestment Act of 2009 through the U.S. Environmental Protection Agency. The total cost for the first four alleys is $1.2 million.

For more information about the Sustainable DC vision, visit https://sustainable.dc.gov.