Cured in Place Pipe Rehabs Sewer

Staff | September 28, 2010

Insituform recently provided an inexpensive and time-saving solution on a sewer rehabilitation project for the city of Pine Bluff Ark. Using its cured-in-place pipe (CIPP), the contractor was able to create new pipe inside 3,000 feet of an existing sewer line, extending its life another 50 years or longer.

The city has approximately 450 miles of sewer line and 48 pump stations. Pine Bluff Wastewater Utility recently formed an infrastructure committee to help keep tabs on areas that are weak and fragile, and make repairs. "We wanted to be proactive about this because eventually the EPA will require cities our size to make these repairs," says Ken Johnson, general manager Pine Bluff Wastewater Utility. "We want the city of Pine Bluff to be ahead of the curve and aggressive towards making these repairs."

Johnson says Pine Bluff is using PVC pipe for all modern applications, but parts of the existing sewer pipe date back to 1933 when the original sewer system was constructed. Failures, stoppages and overflows in 25-year-old duct iron pipe, concrete and older clay pipe caused the city to seek out a cost-efficient way to replace existing lines. At the same time, Pine Bluff Wastewater Utility did not want to inconvenience its customers.

"We've been using trenchless technology for several years," says Johnson. "It allows us minimum service disruption and the process is very efficient."

Johnson says the only other option of excavating a trench near the area and laying new pipe would have been much more expensive, not to mention time consuming. Pine Bluff Wastewater Utility has only earmarked $500,000 over the next five years collected from a 2005 rate increase to make these types of repairs as well as repairs to stressed pump stations over the next five years.

The Cured In Place Pipe (CIPP) was used on one well-worn 3,000-foot stretch of pipe near a creek that often experienced severe seepage problems during stormy weather. Water seeping into the pipes often overtaxed the pump stations.

A temporary bypass line was used to divert around the 3,000-foot area of pipe so that Pine Bluff Wastewater Utility could continue to provide its customers with service during the work.

CIPP is a resin-saturated, coated felt tube that is inverted or pulled into a damaged pipe. The material is refrigerated until use. Once it is pulled into the pipe, hot water or steam is used to cure the resin to form a new jointless pipe. Once cured, robotically controlled cutting devices are used to inspect the rehabilitated pipe by closed-circuit TV, clean up and restore service.

The work was performed in 300-foot segments a week, and completed within a few months. Johnson says the work, along with other changes, has made a difference. "We get a lot of rainfall here in Pine Bluff, but the frequency of sewer stoppages and problems has gone down tremendously. Pine Bluff Wastewater Utility has seen a reduction of over 50 percent in stoppages over the last year alone. Johnson indicated that the new goal was to stoppages by another 15 percent for 2008

"I think we're also seeing savings with pumping stations that don't get the excess water, which reduces our energy costs." Johnson says he has advocated the CIPP process to storm and street sewers for its low cost and efficient placement process. "This is definitely the way to go." A public meeting is planned in April to educate surrounding communities on the CIPP process.