Manholes and catch basins – Case Study

Lining system restores pump station

Problem: After only five years of service, operators at the Washington (N.C.) Wastewater Treatment Plant noticed significant concrete deterioration from hydrogen sulfide in its main sewer pump station. The city considered a mortar/epoxy liner, HDPE liner, or a multi-layered polymeric lining system to rehabilitate the structure.

Solution: The city received quotes on the first two systems and chose the mortar/epoxy liner as the most affordable. Then SpectraShield provided a quote competitive enough for the city to change its mind.

After setting up the bypass systems, utility workers cleaned the station. The SpectraShiled team built scaffolding inside the 20- by 30- by 36-foot-deep wet well, abraded the walls, then bored into them and injected fast-acting SpectraGrout to stop severe leaks. They plugged minor leaks with quick-setting hydraulic cement.

The first layer of the SpectraShield system is a primer designed for saturated concrete. The thin film provides adhesion to the substate. After the primer dried the required four hours, the crew sprayed on a layer of silicone-modified polyurea, followed by a layer of tight closed-cell polyurethane foam to fill voids and restore placement.
The foam dried tack-free in 8 to 12 seconds. The crew then applied a second thin film of silicone-modified polyurea as the final corrosion barrier. It dried just as quickly. The pump station was rehabilitated in a week.

Result: The project was completed two weeks ahead of schedule and 8 percent under budget.