Digging Deep

City of Monroe
Monroe, Michigan
7 million gallons
URS Corporation
General Contractor

The Monroe Wastewater Treatment Plant added a seven million-gallon equalization basin to its property along the River Raisin in southeast Michigan. Walbridge was hired to construct the $14.5 million upgrade, which was designed to contain flows from peak rain events and return the excess water to the plant for treatment once the increased flows subside. The plant had a daily treatment capacity of 24 million gallons.

The new concrete basin occupies 50,000 square feet. With its installation, Walbridge also placed a 24-inch ductile iron force-main pipe that stretches 1,200 lineal feet, connecting the treatment plant to the new basin; as well as various control, monitoring and support systems around the site. The team also brought a significant amount of upgrades, improvements and concrete restoration to the existing facility.

More than 40,000 cubic yards of soil were excavated for the 20-foot-deep, three-chamber basin; roughly 2,000 rammed aggregate piers were installed to support and stabilize the sub-grade below it. Walbridge Concrete Services, a major subcontractor on the job, has placed 11,600 cubic yards of concrete for the basin and its new pumping and conveyance control and monitoring facility.