Completed Wet Weather Treatment Facility Helps Reduce Combined Sewer Overflows

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Treatment Plant Facilities Last week, the District of Columbia Water and Sewer Authority (DC Water) commissioned the first major component of the DC Clean Rivers Program ahead of the deadline outlined by the consent decree. Working with a team of engineers and contractors, a seven-mile-long tunnel segment and a new 225 mgd wet weather treatment facility was put into service. The two components will work together to reduce combined sewer overflows by more than 80 percent.

The design-build joint venture of PC Construction and CDM Smith designed and constructed the new wet weather treatment facility, which receives the overflow stored and transmitted through the tunnel. The facility is designed to treat 225 million gallons of incoming combined sewer overflow, eliminating potential untreated overflow into the Anacostia and Potomac Rivers and Rock Creek.

The construction of the wet weather treatment facility included a 500-mgd tunnel dewatering pump station with five 83-mgd pumps and a 225-mgd enhanced clarification facility utilizing a ballasted, high-rate clarification process to treat the water, providing disinfection before discharge into the Potomac River.

“This project is a crucial component of DC Water’s wet weather plan,” said Kevin McCarthy, president and CEO of PC Construction. “We are proud to contribute to the incredible effort, helping DC Water achieve their consent decree deadline and improve the health of the Anacostia and Potomac Rivers and associated waterways.”

DC Water will continue their efforts with the mining of the next tunnel segment. Upon completion in 2023, the entire tunnel system will capture 98 percent of sewage overflows into the Anacostia and provide more flooding relief for residents who were served by an undersized sewer for decades.