Sewage rides cured-in-place pipeline
By Eloise Aguiar
Advertiser Windward Bureau
KAILUA — An international sewer-line repair company is using technology similar to that used to make surfboards to rehabilitate deteriorated pipes on Kainui Drive, saving the city time and the neighborhood from possible construction-related damage.
The $3.9 million project to repair 3,350 feet of 48- to 52-inch pipe has begun.
Workers set up a sewer bypass line and cleaned the old pipes, and Insituform Technologies Inc. expects to begin installing a resin-soaked felt tube into the damaged pipe within two weeks.
The cured-in-place, trenchless technology will cause fewer disruptions, cost less and have a minimal impact on the community, according to Dwight Ho, technical representative for Insituform, which has been in Hawai'i since 1970.
By contrast, a trenching process would require heavy equipment, trucks to haul soil and a dewatering system.
"With this process we don't have to dewater," Ho said. "It minimizes the impact to the surrounding area."
The system is quick and significantly reduces the amount of excavation, said Carol Costa, director of the city's Customer Services Department. With minimal digging, there are no settlement problems, less traffic disruption and less dust at the site, she said.
The city has used the system at four other projects in Honolulu, Kalihi and Kailua, Costa said. A Nimitz Highway reconstructed sewer project that used the process on 4,150 feet of line recently won first place in the Engineering Excellence Awards sponsored by the Consulting Engineers Council of Hawai'i, she said.
The installation will take about six weeks, with the company rehabilitating one section at a time, Ho said.
Each section takes about 36 to 40 hours to install and once the process begins, it can't stop until it's finished.
The affected neighbors and the Kailua Neighborhood Board were informed about the process at community meetings, he said.
Motorists will still be able to use Kainui during the process but the lane will be cut in half, forcing traffic to slow where the crew is working.
Much of the work will be done off site. The company makes tubes the size of the pipe being repaired out of 1-inch-thick felt.
At the plant, the felt is saturated with resin and refrigerated so the heat-activated resin doesn't harden.
At the construction site the tube is inserted into the old pipe from a high tower. The tube is driven into the pipe using water pressure.
The water presses the felt tube against the host pipe, creating a tight fit.
Once in place, the water is heated to 180 degrees for about one hour to activate the resin.
The water must then be cooled to 100 degrees before it can be discharged into the system. The cured-in-place process adds structural support to the old pipe.
The rehabilitated pipe has a life expectancy of 50 years, Ho said.
Correction: The Kalaheo Avenue sewer repair project did not cause residences to sink and swimming pools and driveways to crack, according to Dwight Ho, correcting a statement he made in an earlier version of this story.
