Quick repair for T. Falls sewer line

In an effort to improve a sewer pipeline in Thompson Falls that had been compromised by blockages from a root system, Planned and Engineered Construction, Inc. (PEC) from Helena was hired by the city of Thompson Falls to complete repairs. Public Works Director Neil Harnett said PEC implemented a cured in place pipe (CIPP) method of maintenance. CIPP is a trenchless method of rehabilitation to repair existing pipelines using a jointless and seamless pipe within a pipe that has the capability to rehabilitate 2- to 110-inch pipes.

The process of using the CIPP involves a resin-saturated felt tube made of a cloth-like material that is inserted into the damaged pipe. Little to no digging is needed with this method, potentially making it more cost effective and less disruptive than ways. The liner can be inserted using water, steam or air pressure. With this project, steam was used to insert and expand the pipe. The heat of the steam reacts with the resin and hardens the pipe in around 20 minutes to form a solid corrosion-resistant replacement pipe.

When PEC began an inspection of the damaged pipe by snaking a camera down into it, they didn’t get further than around 160 feet before being stopped by a root-system blockage. According to Harnett, the root system they encountered was 100 feet long with root diameters of 6 inches. It took nearly a day and a half to get the blockage cleared and cut out. After the prep work the CIPP was inserted and hardened in place quickly, making the whole project last just two days.

The CIPP method works well to cut costs, and also time, Harnett said. The same job done by digging up and replacing the whole 232 feet of damaged pipe would cost an estimated $120,00 to $150,000, and take about a week to complete. The CIPP method cost roughly $50,000. Mike Vetsch, Project Engineer with PEC, has found that CIPP works very well in the higher populated cities as well. When there are a lot of utilities in a closer vicinity, it becomes more difficult to dig up large areas and slipping in the CIPP is a nice alternative.