For instance, Washington, D.C., which is considering whether to renegotiate its own deal with the EPA, is currently drilling the second of three mammoth tunnels designed for one thing: to hold 190 million gallons of untreated sewage and stormwater. The tunnels will be used when the city’s aging sewer system is overwhelmed so that untreated wastewater doesn’t flow into the Anacostia River as it now does — 15 to 20 times a year.