Defining, Understanding Lateral Rehab Options

Part 2 in a series
By Jeff Griffin, Senior Editor | May 2011, Vol. 66 No. 5

Single Inversion Method -- An excavation is made and a section of the lateral pipe is removed. A liner tube is positioned inside of a bladder, and the liner assembly is resin saturated. The liner/bladder assembly is simultaneously inverted into the lateral pipe using air pressure. Prior to curing, an inspection camera can be inserted into the bladder while pressure is maintained to determine proper placement. The liner remains pressed tightly against the wall from the initial inversion until fully cured when pressure is released and the bladder is removed.

Pull-In-Place Method -- This method allows the liner to be installed from an excavated pit or a clean out. Preferably, a pull cable is strung from the clean-out through the lateral and main sewer pipe to a receiving manhole. A resin-saturated liner with a secondary non-stick skin is positioned on a pneumatic plug. The liner/plug assembly then is pulled through the clean out by the pull cable, far enough to get past the clean-out opening. A closed-circuit television (CCTV) camera in the sewer main is used to ensure that the liner is correctly positioned at the lateral terminus and not protruding into the main sewer. The plug is inflated pushing the liner tightly against the lateral pipe until cured. Then the plug is deflated and removed along with the secondary skin from the liner.

Clean-Out Inversion Method -- A resin-saturated liner is frangibly attached to a bladder by simultaneously inverting them through a clean-out. Swelling compression gaskets or other approved seals can be attached to each end of the liner ensuring water can’t track behind the liner. The liner is positioned along the bladder at a point just past the clean out. Inversion pressure keeps the liner pressed tightly against the lateral pipe. Prior to curing, a CCTV inspection camera is inserted into the bladder to insure correct positioning of the liner. The pressure is maintained until the liner is fully cured. Then pressure is released and the bladder removed.