PC Construction and CDM Smith are designing and building a $215 million tunnel dewatering pump station (TDPS) and enhanced clarification facility (ECF) for DC Water's Blue Plains Advanced Wastewater Treatment Plant in Washington, D.C.

The work is part of the comprehensive DC Clean Rivers Project mandated under a federal consent decree between the United States, District of Columbia, and DC Water to store combined sanitary and storm sewer overflows until they can be pumped to the plant. Rainwater from the utility's 725-square-mile service area can overwhelm the system and treatment facilities, resulting in potential overflow into the Anacostia and Potomac rivers as well as Rock Creek.

A 250 mgd TDPS will pump a diluted mix of rainwater and sewage to the 250 mgd ECF, which will utilize a ballasted high-rate clarification process. Treated water will be disinfected before discharge to the Potomac River. The TDPS and ECF will be expandable to 500 mgd.

The design phase will begin in August 2013; completion is expected by March 2018.

“The projects that make up our wet weather plan achieve both nitrogen reduction and CSO abatement, improving the health of our waterways and saving hundreds of millions of dollars,” says DC Water General Manager George Hawkins.

Since 2010, PC Construction has worked on four other projects for the utility with a total estimated value of $375 million.

"We've developed excellent working relationships among our local staff through $300 million of design-build work delivered or under contract, including DC Water’s Biosolids Main Process Train, one of the region's greenest projects,” says CDM Smith Vice President David Schwartz.