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.

The $51-million project was completed ahead of schedule and $9 million under budget.

West Side Diversion Tunnel

Davenport, Iowa

Key Players
Owner City of Davenport
Lead Design Firm Stanley Consultants
Contractor 1 McCarthy Improvement Co./Bellamy; Foley Construction Co.
Contractor 2 Jay Dee Contractors Inc.
Contractor 3 Langman Construction
Consulting Engineer CNA Consulting Engineers
Subcontractor IIHR Hydroscience & Engineering