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Mayor Gray Marks Completion of District’s First Green Alleys

Wednesday, July 11, 2012
Sustainable DC Initiative Helps Control Storm Water Runoff and Pollution

(WASHINGTON, DC) – Today, Mayor Vincent C. Gray celebrated another step forward towards a more Sustainable DC with the completion of the District’s first “green” alleys. Mayor Gray, joined officials from the District Department of Transportation (DDOT) and the District Department of the Environment (DDOE), watched as workers poured water on a newly constructed alley in Northeast Washington to demonstrate how stormwater seeps into the permeable surface rather than running into storm drains – helping cut one of the major causes of waterway pollution.

“The water disappears, but it’s not a magic trick – it’s smart, green, cutting-edge urban design that puts the District at the forefront of sustainable practices nationwide,” Mayor Gray said. “Improving the health of our rivers and streams starts in our neighborhoods with creative solutions like these 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 DDOT and DDOE – is aimed at reducing the quantity and improving the quality of stormwater runoff within the District’s right-of-way.

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. The sites are located along the Watts Branch Watershed at the following blocks:

  • Alley between 54th Street, Blaine Street, 55th Street, and Clay Street NE
  • Alley between 56th Street, Eads Street and 57th Street NE
  • Alley between 58th Street, Dix Street, 59th Street and Clay Street NE

DDOT constructed its pilot green alleys by replacing gravel, impervious concrete or asphalt surfaces with permeable concrete. Permeable pavement has pores or openings that allow water to pass through the surface, then percolate down through a gravel layer and into the soil below rather than running off into sewers.

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 Wards 3, 4 and 5 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 US Environmental Protection Agency. The total cost for the first four alleys is $1.2 million.

For more information about the Mayor’s Sustainable DC vision, please visit the Sustainable DC website. Details about DDOT’s Green Alley Project are also posted online at ddot.dc.gov.