Case Study: Scanning system locates problems in new CIPP

Case Study: Scanning system locates problems in new CIPP
The Electro Scan monitor clearly shows a wrinkle in a newly installed CIPP liner.

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A northern California coastal sewer agency found numerous wrinkles after a recent CIPP liner installation. While an independent consulting engineer determined that the wrinkles did not impede the flow or warrant further investigation, staff engineers suspected that the liner was compromised and could be a source of infiltration. 

The agency conducted an Electro Scan survey, assessing the 15-inch, 300-foot CIPP-lined VCP sewer main. The survey, which was done in accordance with ASTM F2550-13, showed that the liner could potentially leak at the wrinkles identified by the CCTV operator, as well as at a nearby service connection that had not been properly restored. The combined infiltration rate (plus-or-minus 40 percent accuracy) of the pipe segment was estimated to be 21.84 gpm. 

The agency is working with the contractor over the concerns with the CIPP liner as part of its warranty. The agency is also considering the use of Electro Scan to assess other post-CIPP anomalies, including discolored and over-cooked markings. 

Future specifications for new construction and relining will require Electro Scan to calculate a pre- and post-CIPP gpm defect flow rating, showing estimated flow reductions from before and after rehabilitation. 916/779-0660;


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