Federal authorities have given approval to DC Water and the District of Columbia to modify their combined-sewer-overflow plan and incorporate large-scale green infrastructure.
Under a deal with the U.S. Environmental Protection Agency and the U.S. Dept. of Justice announced on May 20, the agency can eliminate a planned underground tunnel along Rock Creek. The agreement calls for green infrastructure—such as rain gardens, green roofs and porous-pavement installations— as well as targeted sewer separation. The system's design allocates 365 impervious acres of land along Rock Creek for management of up to 1.2 in. of rainfall. A planned tunnel along the Potomac River also is scheduled for modifications. The revised design will hold up to 30 million gallons of combined stormwater and sewage that will flow to DC Water's advanced wastewater treatment plant at Blue Plains. In addition, 133 impervious acres of land will be used to manage up to 1.2 in. of rainfall.