New Technology Saves a Sewer Interceptor—and $1.5 Million!

By Angus W. Stocking, L.S. | January 2011 Vol. 66 No. 1

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There was some good news. According to their findings, MIC was confined almost entirely to within 25 feet of trunk line entry points. Therefore, conceivably, Westlake could save money by focusing on problem areas and leave the rest of the interceptor alone. In theory, this would save about half of the cost of cured-in-place-pipe (CIPP) rehabilitation, because the overall footage of rehabilitated pipe would be reduced by more than half. “We actually did a whole design based on that idea,” says Kelly.

But there were problems with that approach. CIPP is, of course, a well-proven technology for pipe rehabilitation but it was not a good choice for the particular situation in Westlake. For one thing, CIPP runs are generally manhole-to-manhole, and there is not much money saved by specifying shorter, partial runs. CIPP also is not a good fit when pipe diameter changes, as it does several times in the Westlake interceptor. Finally, manholes that serve the interceptor are quite deep in places, and they would have to be excavated and dismantled to maneuver in felt linings -- this was more work than Westlake wanted to do for a partial rehabilitation.

These small challenges added up to one big problem. Westlake was trying to avoid using state or federal money for this project; they had approximately $2 million available to use. “When we added up all the costs of our CIPP design, it came to over $3 million,” exclaims Kelly. “We did not know what to do.”

In search of ideas, Smolik attended the Pumper & Cleaner Environmental Expo in Louisville, KY. After a great deal of research and conversation, he returned with two good ideas: a new product and a new technology.

The new product was ConmicShield, a concrete additive that permanently inhibits MIC. ConmicShield is a concrete additive that is easily dosed into concrete and bonds molecularly with the concrete. Even though ConmicShield is not toxic to humans or animals, the treated concrete is anti-microbial, and permanently prevents the growth of Thiobacillus bacteria for the concrete’s entire lifecycle. ConmicShield protection is not new; it was used in shotcrete for a major trunk sewer rehab in 1997 in Atlanta, GA. A number of large municipalities, including Chicago, in the world’s largest manhole rehabilitation project to date, has since adopted it.

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