Timely Solution

July 2009 Vol. 64 No. 7
After the splitter box discharges were cleaned and prepared (left), they were lined with CIPP (right) and sealed.

Cured in place pipe (CIPP) technology and professional planning from Inliner Technologies provided a timely and cost effective solution for damaged pipe at a wastewater treatment plant near the Mississippi River.

User-friendly Vipel polyester resin from AOC contributed to the project’s success.

The T.E. Maxson Wastewater Treatment Plant of the City of Memphis, TN, has four, 180 foot diameter primary clarifiers. Clarifiers 1, 2 and 3 were built in 1980 with 54 inch diameter concrete inlet pipes. Looking forward, engineers designed the splitter box that distributes effluent to the clarifiers, to allow for a fourth clarifier, which was added in 1996 with a 48 inch diameter concrete inlet.

After 27 years, the floor of Clarifier 2 started shifting enough to affect the operation of the clarifier’s scraper arms. Inspections showed that the ground beneath the clarifier needed to be stabilized and the underground inlet pipes for Clarifiers 1 and 2 needed to be repaired.

“Over the years, the concrete pipe was exposed to highly corrosive sewer gases in a constantly moist environment,” said Ken Thompson, operations manager for Inliner. “The most severe damage was an opening in the crown of one pipe that was approximately 70-feet in length and 15 to 18-inches wide. Inlet pipes for Clarifiers 3 and 4 were CIPP lined as a proactive, precautionary measure.”

Steve Lindsey, senior pipelines rehabilitation specialist, Jordan, Jones & Goulding, Inc. (JJG), designed the pipe project. “Because the inlet pipes run under the clarifiers, excavation and replacement was out of the question,” he said. “It was essential to keep the plant running, so the repairs had to be scheduled to coincide with planned maintenance down times.”

No more than two clarifiers could be shut down at any given time and then only for short periods. The plant’s maximum flow rate is rated at 160 million gallons per day. The design average daily flow is 90 million gallons

Seamless

Reynolds Inliner repaired the entire lengths of the four inlet pipes, including the steel discharge elbows that taper out of the splitter box in a 20 foot-long, sweeping 90 degree turn. Reynolds Inliner used the inversion process to install new, seamless liners into the discharge and pipe.

Each liner section consisted of a special felt tube that was impregnated with a Vipel unsaturated polyester resin in a wet out facility. AOC chemists engineer CIPP resins to provide consistent wetting, handling and cure characteristics. The wet out tubes were shipped to the job site in a refrigerated truck to prevent premature resin cure.

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