Detroit, MI
GeoSpray®: Non-Reinforced Concrete Sewer Lining

Project Overview

In May 2016, a massive sinkhole formed underneath Tireman Avenue in Detroit, Michigan. The root of the problem was a fractured sewer line. A damaged pipe leading to a major concrete interceptor caused heavy infiltration, which in turn resulted in soil loss around the interceptor at the fractured location of the pipe. The soil loss eventually worked its way to the surface to create a 12-foot wide sinkhole, forcing the closure of Tireman Avenue and major public disruption. The pipe was directly below multiple utilities, including a 16-inch high-pressure gas main. If the interceptor totally failed, then the utilities were at risk of catastrophic damage.


The 1930’s design had the flow from the connection emptying near the crown of the interceptor, and this vertical drop created turbulence and ultimately the formation of H2S gas, which ate away at the secondary liner. This corrosion was discovered when the sinkhole appeared, but had been corroding for decades.

The straight section of the interceptor was repaired with a 78-inch HOBAS pipe. The curved portion of the interceptor, however, made it unsuitable for this type of rehabilitation. IWPC proposed and designed an alternative repair, which included the installation of conventional "I" section ribs with tie rods for reinforcement and wood lagging in between, followed by the application of GeoSpray® geopolymer mortar as a preferred structural repair solution for this section of the project. When the area had been cleaned, relined and grouted, GeoSpray® mortar was sprayed onto the new ribs and lagging. Grade nails were installed to verify the specified 1.75-inch thickness required for the curved portion.

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