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CIPP Lining A Cost-Effective Solution For Corroded Concrete Pipes
An engineering firm brought in to review the matter recommended either pipebursting or relaying the entire section of damaged pipe. Both cost estimates were high, Lui said, so the Utility District turned to Foth Infrastructure & Environment LLC, of Milwaukee for further analysis. Project Manager Michele Klappa-Sullivan, P.E, said her engineers realized immediately that pipebursting would not work on the reinforced concrete pipe. Plus, the sewer pipe lies precariously close to two 60-inch water mains. “We quickly determined that we needed to come up with a different solution,” Klappa-Sullivan said, “and we needed to find out what the rest of the pipe condition was.”
The Utility District asked Visu-Sewer Inc., of Pewaukee, WI, to televise the section of pipe and provide some recommendations. Televising showed that the hole in the pipe was just the beginning, Lui said. Four spots in the pipe were bad enough to warrant replacement, along with other sections that were deteriorating.
More than a hole
While the sinkhole was the most obvious problem, said Keith Alexander, president of Visu-Sewer, televising revealed that hydrogen sulfide gas had eaten through the pipe in numerous places. The worst spot on the 20-year-old pipe caused the cave in and sinkhole.
“We asked, ‘Can this thing be relined, or is it too bad?’ ” Lui said.
Visu-Sewer recommended replacing the worst portions of the pipe and rehabilitating the rest with CIPP lining by National Liner. “The cost to do the spot relays and relining was substantially cheaper than full pipe replacement,” Lui pointed out.
For Visu-Sewer, this project offered the firm an opportunity to showcase its expertise and experience. “We were confident we could get it done on time and deliver a good product,” Alexander said.
Concrete pipe is common for water systems, but is susceptible to corrosion when used in sanitary systems. If conditions are right, the sewage can turn septic, Alexander said. Sulfide gas will build up, causing the concrete to deteriorate.
The process began with Reesman’s Excavating creating digging access points to the pipe. One crew from Visu-Sewer cleaned and televised the pipe. Afterward, a second crew arrived to install the CIPP pipe. Because they were working with a force main, Alexander said, the firm incorporated end seals in the pipes.