The District’s Green Alley Projects are designed to reduce the quantity and improve the quality of storm water within the city’s right of way (ROW). Although alleys constitute a significant portion of impervious surface, 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 by increasing water infiltration and treatment on site.
Typical cross section of a green alley with permeable pavement:
The District Department of Transportation (DDOT) constructs Green Alleys by removing gravel, impervious concrete, or asphalt surfaces and replacing them with a permeable surface such as pervious concrete, porous asphalt or permeable pavers in areas where the storm sewer and sanitary sewers are separated. 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.
Completed Green Alley Projects:
- Alley between 54th St, Blaine St., 55th St., & Clay St., NE
- Alley between 56th St, Eads St., & 57th St., NE
- Alley between 58th St, Dix St, 59th St., & Clay St., NE
- Alley between 49th Pl, Nannie Helen Burroughs Ave., 50th St, & Hayes St., NE
- Alley between Q St., Q Pl. and 45th St., NW
DDOT implemented these green alleys in partnership with the District Department of the Environment (DDOE) with funding from the American Recovery and Reinvestment Act of 2009.
Upcoming Green Alley Projects:
|Rittenhouse/ Chevy Chase Green Alley||Pervious Concrete||Alley between 34th Pl., Broad Branch Rd., Rittenhouse St., 33rd St., and Quesada St., NW||2014|
|RiverSmart Washington||Pervious Concrete, Permeable Pavers, Porous Asphalt||5 Alleys between Iowa Ave., Allison St., and Webster St., NW; 5 Alleys between 32nd St., Broad Branch Rd., Rittenhouse St and Patterson St., NW||2014|
|Ashley Terrace Green Alley||Porous Asphalt||Ashley Terrace Alley between Highland Place, Ordway St., and 30th St., NW||2015|
Please contact DDOT Stormwater with any questions or comments about this program.