Dearborn Combined Sewer Overflow #8

Location: Dearborn, MI

Summary

This project began small with Smith’s installing coatings for the primary and secondary containment for sodium hypochlorite at Dearborn CSO#8 (Combined Sewer Overflow). This required a protective coating of vinyl ester to be installed to resist the corrosion and acidity of the sodium hypochlorite, which has the ability to dissolve stainless steel. To prepare the surface, Smith’s crews sandblasted and cleaned both tanks before applying the chemical resistant vinyl ester coating.

The inspector and engineer onsite acknowledged the high quality of work and after tank coatings were complete, Smith’s was instructed to perform crack injection on the caisson as part of a work change directive. Though the caisson was new, it required crack injection at the cold joints where water was leaking through. Smith’s utilized a manbasket to inject cracks with both hydrophilic and hydrophobic polyurethane injection grout on the caisson. Smith’s also performed polyurethane crack injection on the influent lines to eliminate leaks.

Following the crack injection, Smith’s installed an architectural expansion joint around the perimeter of the caisson. The expansion joint was installed between the top of the caisson and the roof or lid of the caisson. The lid is removable and the expansion joint protects the caisson from any movement of the lid.

The roof of the caisson received a living roof which allows grass, bushes, and small plants to grow on top of the concrete roof. This particular living roof required a two-part membrane system, with soil layered between each membrane. Smith’s was chosen to install the Firestone membrane system, which also included engineered soil and vegetation.

The owner of the project was satisfied with the work performed by Smith’s, which resulted in contracts to work on three other CSO projects.

Highlights

• Vinyl Ester coating protective coating of primary and secondary containment tanks
• Crack injection and waterproofing of caisson and influent lines
• Green/ living roof membrane installation