Location And Leak Detection

Location And Leak Detection
Electronic solution used to identify defective liner

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Electronic solution used to identify defective liner

Problem: The James City Service Authority in Williamsburg, Va., contracted with a national CIPP lining company to use trenchless technologies to rehabilitate 15- and 18-inch Flextran gravity sewer pipe. Installed in the early 1970s, it is a thin-walled fiberglass pipe that has proved susceptible to structural failure. The anticipated rehabilitation involved CIPP lining to strengthen the host pipe and significantly reduce storm and groundwater infiltration in the sanitary sewer system. Danny Poe, P.E., project manager for JCSA, required the lining contractor to CCTV and Electro Scan all post-CIPP linings prior to acceptance.   

Solution: Electro Scan identified one segment out of nine where the liner had been compromised, i.e. representing locations of possible infiltration. Originally, the lining contractor had not identified any defects using CCTV. Using Electro Scan, the inspection indicated an estimated defect flow of 3.12 gpm, representing 310 feet, or 15 percent of the total length of the project scope. 

Result: In spite of a number of difficult access reaches, Electro Scan inspected 100 percent of the lines, approximately 2,100 feet, in a single day, with the defective liner removed and replaced by the CIPP contractor, at no additional charge. 916/779-0660; www.electroscan.com.

Helium technology used to locate leak in 8-inch main

Problem: The United Water system in Harrisburg, Pa., serves approximately 37,000 residents. As part of United Water’s loss reduction measures, the company routinely and proactively conducts leak surveys of the system itself. United Water became aware of at least one leak on a section of polyvinyl chloride (PVC) water line in Hummelstown. The company sought to eliminate the water loss by promptly finding and repairing the leak.

Solution: The company looked into the effective utilization of tracer gases to isolate leaks. They tapped Utility Service Group to conduct a leak detection survey using Helium Leak Detection Technology on a 1,000-foot section of 8-inch-diameter PVC water main. The technology has been used since 2007 and has proven effective in locating leaks in drinking water systems for all pipe materials and sizes.

Result: A small mainline leak was located on the 8-inch PVC line, and a larger water leak on a service line. From recording the water flowing into the water zone before and after the repairs by way of a water meter, it was ascertained that the leak on the 3/4-inch service line was losing approximately 2 gpm. 855/526-4413; www.utilityservice.com


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