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IPR, EcoCast Thwart Threat Of Sewer Collapse
The threat that a large, severely deteriorated Houston sewer line could cause the collapse of a road at the intersection of a major highway was averted by a timely trenchless rehabilitation project.
EcoCast geopolymer liner was used to reline 700 feet of 72-inch diameter pipe that crosses under heavily-traveled U.S. Highway 59 in Northeast Houston.
The section of reinforced concrete pipe is a part of the city’s gravity-flow sewer infrastructure. It was 42-feet-deep and had been in the ground for 20 years. The pipe was leaking at multiple joints with infiltration a major concern. Ground above the pipe adjacent to the highway had shown significant settling.
“The original plan was to renew the pipe with cured-in-place pipe (CIPP),” said David Tajadod, managing engineer, the city of Houston. “But problems arose with the arrival of extremely high temperatures in the city which could affect that process, and we needed to find another method of construction so we could proceed.”
The entry excavation had already been completed and the bypass system was in place, Tajadod explained.
“We didn’t want to abandon the excavation,” he said, “and there was concern that the pipe would not make it until the fall.”
After considering the various options available, EcoCast was determined to be the best procedure for the project. The contractor was Inland Pipe Rehabilitation (IPR).
EcoCast is a high-strength, fiber-reinforced geopolymer that can be applied by mechanical pumping, spraying and trowel application. EcoCast liners form a crystalline structure for higher resistance to acids and greater surface durability, says IPR, developer of the product with development partner GeoTree Technologies. For the Houston project, the liner was used in conjunction with the company’s Anti-Microbial System (AMS), a coating that bonds to the geopolymer surface and destroys bacteria that causes corrosion.
The extreme depth of the pipe and limited access because of the distance between manholes were two factors that drew attention to EcoCast, said Nick Banchetti, IPR general manager.
Hot summer temperatures also complicated the installation.
“At the time [summer 2011], we were in the middle of the longest, hottest drought in the history of Texas,” said Banchetti. “Temperatures were over 100 degrees for about 90 percent of the time that work on the project was under way.”
Banchetti said one benefit of using EcoCast is that it avoided concerns that extreme heat can cause other technologies to begin curing prematurely.