A recent sewer project involving cured-in-place-pipe (CIPP) rehabilitation revealed several important design and feasibility parameters, and construction challenges that are unique to, and more critical for CIPP rehabilitation of small diameter pipe than for larger diameter pipe. This project included of more than 45,000 linear feet of 6-inch and 8-inch inside diameter (ID) gravity sewers and was located on a densely developed urban hillside in Honolulu.This paper discusses lessons learned by the construction management team on this project and provides information that project owners, engineers, and contractors can use during design, bidding, and construction of small diameter rehabilitation projects, including:1.Assessing feasibility of rehabilitating small diameter sewers2.Importance of identifying and evaluating severity of offset joints, protruding cracks and laterals3.Capabilities and reliability limitations of current small diameter CIPP, television inspection, and lateral reinstatement equipment4.Significance of CIPP liner defects in small diameter pipe and increased challenges to correct defects5.Preparing contract documents, including contractor and personnel pre-qualification requirements that are specifically developed for small diameter pipe rehabilitation projects6.Production rates and quantity of sewers deemed not-feasible for CIPP rehabilitation of 6-inch and 8-inch diameter sewers on this project.
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