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Sewer rehabilition liner being insalled into a sewer through an indoor facility

St. Paul Sewer Interceptor

Michels Trenchless, Inc. rehabilitated more than a mile of sanitary sewer pipes on the St. Paul Interceptor. The project included 670 lineal feet of 56-inch, 4,418 lineal feet of 60-inch, and 2,250 lineal feet of 72-inch diameter pipes. Crews used cured-in-place pipe (CIPP) liners made of 5-8 layers of felt inside corrosion-resistant coated liners impregnated with resin. Liners were cured in place with hot water, except one installation. The 90-foot installation of 72-inch pipe had a 13-foot elevation change and was cured with steam.

The project was completed in 12 installations ranging 90-1,480 feet over 4 months. A 2,400-foot second phase was completed in two months.

Installing liners 25-50 feet below ground was challenging. For example, when the 72-inch liner was filled with resin, it weighed nearly 200 pounds per foot. The crew added a special hydraulic brake to the roller setup to control its speed being lowered into the manhole. In addition, one 90-foot section had a 13% grade change, far more than the typical 0.5-3%.

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