WILLMAR - A process used in the United States for more than 30 years to rehabilitate sewer lines without digging them up is being used for the first time on a sewer line project in Willmar.
The process, called Cured-In-Place Pipe, creates a pipe-within-a-pipe and is more or less like placing a stent in an artery.
The process was used during the past couple of weeks to upgrade a portion of the sanitary sewer line under Lakeland Drive Northeast.
The work is part of a larger project that’s replacing an aging sanitary sewer lift station with a larger lift station located on the Minn-
West Technology Campus and installation of new sewer pipes under upper Lakeland Drive.
Use of CIPP, as it is also known, is much less expensive than excavating the street and replacing old sewer pipe with new pipe, according to those who have worked with the process.
City Public Works Director Sean Christensen said CIPP was used in Powell, Wyoming, where he served as public works director before coming to Willmar this past March.
“It’s a good process,’’ says Christensen. “This was undertaken because it was considerably less costly but still an effective way to keep using the existing line.’’
The process involves the use of a long fibrous sock impregnated with tiny styrene pellets and turned inside out.
The process begins by placing the sock into a manhole and using air pressure to push the sock along the pipe. As the sock goes along the pipe, air pressure turns the sock right side out, with the styrene-impregnated side of the sock now touching the inside of the sewer pipe.
After the sock is blown through the pipe, steam heats the sock to a temperature that activates the styrene, which causes the sock to adhere and harden against the inside of the sewer pipe.
Don Broberg, construction manager with Bollig Inc., of Willmar, the firm selected to engineer the project, said the fibrous material dries and hardens to a three-eighths-inch thickness.
It is almost like a brand new pipe.
In addition, the new surface covers up areas at the top of the existing concrete pipe where sewer gas created by chemicals in the sewage has exposed some of the reinforcing wire mesh. The exposed mesh was seen when the sewer line was televised.
“We’re still relying on the concrete pipe for strength for carrying the road surfaces,’’ Broberg said. “But this is more durable and resilient against the chemicals that are in the sewage.’’
Engineers from Bollig Inc. discussed several project options with the City Council for upgrading the nearly 60-year-old Lakeland Drive sewer pipe, and the council selected the CIPP process.
The CIPP work was done by Insituform of White Bear Lake.
A pioneer in cured-in-place pipe technology, Insituform has installed more than 19,000 miles of CIPP worldwide, according to the company’s website.
Charlie Huesman, Insituform general superintendent, said the project has gone well.
Cured-in-place pipe technology has been used in the U.S. since the 1980s. Paul Jurek, Bollig project engineer, said the application for CIPP must be appropriate.
“If the pipe is collapsing, that’s another issue, replacement issue or different options,’’ said Jurek.
The $2.421 million Lakeland Drive project spans from the new lift station on the MinnWestCampus to a location just south of U.S. Highway 12.
The current lift station, and the sewer line under Lakeland Drive, were constructed in the 1950s.
