Heavy rain in Washington brings flooded roads and slow commutes — and sewage overflows into local rivers. Monday’s storm was the first test of a new $2.6 billion tunnel designed to prevent those overflows.We saw the opening of the tunnel a few days before it opened, and I predicted it would be big step forward. It is, but if it leaked 10% in the little rains we had last week, what is going to happen in one of our gully washers or tropical storms. Fortunately this is the 2nd of 4 planned tunnels.
The tunnel worked as intended, according to DC Water, preventing roughly 170 million gallons of sewage and rainwater from flowing into the Anacostia during heavy rainstorms earlier this week. The 23-foot diameter tunnel runs under the Anacostia River to Blue Plains treatment plant, where the water and sewage can be processed. The tunnel can hold more than 100 million gallons, and Blue Plains can treat 225 million gallons a day.
Even with the new capacity, Monday’s storm filled the tunnel, causing between 10 and 20 million gallons to overflow into the Anacostia. That’s about 10 percent of what would have spilled into the river without the tunnel.