Combined sewer overflow (CSO) from sanitary and storm water polluted the Potomac and its tributaries for several years, creating the need for a large scale discharge control program to capture and purify water before it reached the three waterways.
The District of Columbia formed the DC Water Clean Rivers Program to reduce pollution in Rock Creek and the Anacostia and Potomac rivers over a 20-year period. The $2.6 billion consent decree program, required by the U.S. Environmental Protection Agency, is removing pollutants harmful to the public and wildlife.
WSP is providing construction and inspection management, quality assurance, project controls, and environmental inspection for the program. WSP is responsible for three divisions of the Long Term Control Plan (LTCP) to mitigate discharges into the Washington waterways:
- Division A of the plan is the Blue Plains Tunnel, which is five miles long, 140 feet deep and 23 feet in inside diameter, and is the first of three major new tunnels in the LTCP to capture and store CSO.
- Division C involves the building of structures to divert CSO out of an existing trunk sewer and into a future Anacostia River tunnel system.
- Division E is a design-bid-build CSO diversion structure and tunnel system in the vicinity of M Street and 12th streets in southeast Washington, D.C.