The 3.1-mile-long West Side Diversion Tunnel is a sanitary sewer that has been a decade in planning and four years in construction. Its primary purpose is to relieve stress on the city of Davenport’s aging sewer system and open up nearly 10,000 acres for future development.

A 60-in.-dia gravity sewer 1.4 miles long was installed from 40 ft to 140 ft deep via a tunnel-boring machine. The rest of the tunnel was open-cut. Challenges included two major Mississippi River floods, extensive unanticipated subterranean dewatering and an unexpected pocket of oil.