The Deep Tunnel project in Chicago is designed to deal with sewer overflow. A tunnel will carry water to a "huge bathtub" that will hold 7.9 billion gallons. The reservoir portion is nearly done, as a final explosion is planned at the Thornton Quarry next week. The project is part of the city's multibillion-dollar program, begun in the 1970s, to "ease flooding on the South Side of Chicago and in the southern suburbs."