CIPP Lining A Cost-Effective Solution For Corroded Concrete Pipes

By Thomas R. Fuszard | July 2010 Vol. 65 No. 7
A piece of the corroded pre-stressed concrete cylinder pipe that was removed from the job.

“In a gravity system, everything flows through randomly,” he explained. “But with force main, you have pressure pushing fluids back behind the liner, causing problems. A seal at the end doesn’t allow any fluids to go behind the liner.” Visu-Sewer repaired a total of 2,105 feet of 30-inch force main and televised an additional 1,200 feet of pipe.

Since this pipe was a force main, an end seal was necessary to avoid fluids pushing back down the pipe and behind the liner.

Challenges
While working on the spot relays, flow was diverted into pipes owned by the city of Racine. But even that proved to be a challenge. They were diverting from a 30-inch force main into a 12-inch pipe, Lui said, which meant they could divert only during low-flow conditions.

If storms were predicted, Lui called Visu-Sewer or Reesman’s, and in a matter of three or four hours, the connection would be closed. “I have to give the utmost credit to Visu-Sewer and Reesman’s for suggesting something like this,” Lui said. It involved some additional expense, but allowed them to return to their force main on a short notice. Best of all, there were no basement backups.

“We had absolutely zero flow issues during the whole duration of the project,” Lui observed. “It was a very well thought out and managed project that went very smoothly.”

The pipe had to be closed and reopened four times due to wet weather, Alexander added.

Klappa-Sullivan credits Visu-Sewer and Reesman’s Excavating for carefully working around sensitive areas near Racine’s water treatment plant. “Because one of the sections was longer than the other,” she said, “we needed to avoid digging anywhere near the main water feeds and the backwash filter feed from the treatment plant.” A project like this normally would entail four or five access points, she said, but they kept the number to three to minimize holes in the road.

Adding to the complexity was that the section of pipe included two bends that, on paper, were 45 degrees, but which actually were “more like sweeping 90s,” Alexander pointed out. They even got stuck in one bend for several hours, he said. To compensate, Visu-Sewer’s crew increased the column height. That increased the water head, which in turn pushed the liner through the bends.

To gain enough head pressure to make the sharps turns required on this project, a crane was brought in to elevate the liner even higher.

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