Nothing Rosy about a Failed Sewer: Rehabilitation of the Rose Canyon Trunk Sewer


Nothing Rosy about a Failed Sewer: Rehabilitation of the Rose Canyon Trunk Sewer

Authors:

Casey Raines, GHD, Irvine, California
Greg Watanabe, GHD, Irvine, California

Abstract: The Rose Canyon Trunk Sewer (RCTS) is a plastic-lined reinforced concrete pipe (PLRCP) with weld strips installed at each joint. From visual and video inspection, it was discovered that the weld strips at the pipe joints had failed, subjecting the pipe to hydrogen sulfide, which decomposes concrete, and ultimately jeopardizing the structural integrity of the RCTS. The RCTS runs throughout an open space environmentally sensitive area rich with riparian habitat. Other challenges included multiple railroad crossings, an adjacent 2,000-foot wide stretch of freeway and several commercial properties. Numerous trenchless rehabilitation options were evaluated to repair the failed plastic liner weld strips in a 4.5 mile section of the RCTS which amounted to approximately 1,150 54-inch and 60-inch diameter joints. The evaluation considered the potential environmental, encroachment and traffic impacts of the rehabilitation and the available sewer bypass piping routes. Internal mechanical pipe seals and new plastic liner strips were selected to repair the pipe joints and were installed via manned entry of the trunk sewer. Although their installation is labor intensive, these methods were the least invasive to the Rose Canyon habitat and the most cost effective. To complete the necessary repairs, a 32 million gallons per day (MGD) bypass system was designed consisting of two temporary pump stations, 2,100 lineal feet (LF) of 32-inch high-density polyethylene (HDPE) bypass piping, and the installation of fabricated stop logs and a temporary bulkhead upstream of the work. Details of the development of the rehabilitation and bypass design which attributed to its success will be discussed.

Publication Date: 2018

Presented at:
NASTT’s 2018 No-Dig Show Palm Springs, California
March 25-29, 2018 | Paper Number: MM-T1-04


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