Photo courtesy of the Washington Post.
Last night the ANC met for its June session. And as predicted by GM, the most interesting topic was overflowing sewage.
To Tunnel or Not to Tunnel
David McLaughlin, Director of Engineering and Technical Services for DC Water, presented on behalf of the sewer authority. As a bit of background: in 2004, the DC water and sewer authority (WASA, which it still is technically called, although it uses the trade name DC Water these days) entered a consent decree with the federal government to address the fact that in the older parts of the city, the household sewers and the storm drains are combined.
When storm drains get overwhelmed (like, say during Sunday’s squall) the combined system overflows into the Potomac and Anacostia rivers and Rock Creek. Thus what you flushed down the toilet Sunday night might now be drifting down the Potomac. Completely untreated.
As part of the decree, WASA/DC Water has agreed to build giant tunnels along the rivers. These tunnels will act a massive subterranean reservoirs to capture the overflow and hold it until the Blue Plains water treatment plant is ready to process it.
The Georgetown waterfront has about half a dozen sewage overflow spots. According to McLaughlin, at the location of each of these overflows a housing will need to be constructed to captured the overflow before it goes into the river. Then the water will be sent down massive access drains (McLaughlin said they could be as wide as 50 feet across) down to the tunnel. The tunnel itself will be 100 feet deep and over 100 feet wide. (They’re already digging a similar tunnel from the Blue Plains treatment facility to the southeast waterfront). Continue reading