Summary of South Thornton Interceptor Manhole Remediation
Denver, Colo.

The photographs in this appendix show manholes in Denver, Colorado that had failures due to corrosion or insufficient rehabilitation at the time of inspection. More than two-dozen of these manholes had been rehabilitated with spray-on epoxy products. The failure of these spray-on epoxy products resulted in added groundwater infiltration and further deterioration of many of these manholes. Additionally, the spray-on epoxy products failed to prevent corrosion by H2S gas released from the sewer system.

Bubbling during the curing process of spray-on epoxy products can be observed in the photo of Manhole Station 30. This type of bubbling of spray-on epoxy products can damage the concrete structure of the manhole when the expansion of the spray-on epoxy causes concrete swelling. Further examples of major bubbling and failure can be seen in Manholes 32, 33, 34 and 36.

This is just a representative sample of the visible failures of spray-on epoxy products. Another Denver manhole, designated MH 41, is located in a residential backyard and has major failures of spray-on epoxy. Each photo shows substantial failure of spray-on epoxy products, necessitating repeated applications for proper rehabilitation. Each additional application runs the risk of failure, and further deterioration of the manhole. Furthermore, failed rehabilitation through the use of spray-on epoxies adds to the expenditure of greater resources such as time, money and water.

Manhole Station 30

Manhole Station 32

Manhole Station 33

Manhole Station 33