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ST. LOUIS COUNTY, MO (KTVI) – Crews with the Metropolitan Sewer District are using state of the art cured-in-place-piping (CIPP) to replace a three-mile stretch of wastewater sewer off Lemay Ferry in south St. Louis County. What is unique about CIPP is that it allows crews to replace old worn down sewer pipes literally from the inside out.

Crews have been working on this stretch of sewer since late September. The CIPP process works a lot like angioplasty on a clogged artery. Crews force a new tubular sleeve made of a special resin through an existing sewer line. It is a process than can take a few minutes to a few hours depending on the length of the run.

The next step is to inject the sleeve with steam or very hot water. The pressure expands the sleeve into a tube and the heat activates the resin. Within a couple of hours, the resin hardens into a solid plastic coating, effectively creating a new sewer line inside the old.

MSD says this is a very cost effective process as it reduces the overall cost by 80 percent and can increase the flow by 30 percent.

It is also a fairly quick process. On smaller lines, it is likely an entire run can be down in a neighborhood during the course of a single work day.

MSD is using CIPP all over their network at rates greater than any other sewer district in the country. It is part of their multi-year effort called “Project Clear,” which is designed to improve water quality and mitigate wastewater concerns throughout the St. Louis area. The project off Lemay Ferry is rather large and the pipes are some of their largest at 42 inches. MSD expects to complete the project by the end of the year.