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RETROSPECTIVE STUDY OF CIPP LINERS USED FOR REHABILITATION IN COLUMBUS, OHIO AND DENVER, COLORADO
Citation:
Alam, S., E. Allouche, A. SELVAKUMAR, R. Sterling, W. Condit, J. Matthews, AND K. Fields. RETROSPECTIVE STUDY OF CIPP LINERS USED FOR REHABILITATION IN COLUMBUS, OHIO AND DENVER, COLORADO. Presented at Water Environment Federation (WEF) Collections 2011, Raleigh, NC, June 12 - 15, 2011.
Impact/Purpose:
To inform the public.
Description:
Cured-in-place pipe (CIPP) has been used for the rehabilitation of deteriorating wastewater pipes for nearly 30 years in the US with much success. However, little quantitative data is available regarding the performance of these liners, which can confirm their estimated design. With more than 70 million feet of CIPP liners installed worldwide, utilities and municipalities seek verification that these rehabilitation systems, expected to have a service life of 50 years, are performing up to their design life. As part of the U.S. Environmental Protection Agency (EPA)’s Aging Water Infrastructure Research Program, one of the key areas of research being pursued, in collaboration with water utilities, is a CIPP retrospective study. The purpose of this study is to (1) determine the engineering properties of aged, in-service, CIPP liners and compare these with original design values; (2) identify and provide insight into degradation mechanisms and deterioration rates of CIPP liners; and, (3) attempt to provide a more accurate estimate of the service life of CIPP liners. This paper describes the testing of two CIPP liners installed in 8” VCP host pipes in Denver, CO, in 1983, and Columbus, OH, in 2005. Specimens prepared from the exhumed samples were subjected to an array of tests including ASTM D638, ASTM D790, hardness, hydrostatic buckling, Raman spectroscopy and geometrical correctness. In addition, standard soil and pH tests were performed on the surrounding bedding materials and the residuals found within the liners. Results were compared with design values available during the time of installation as well as controlled specimens prepared in the laboratory. This project represents the first known attempt in the USA to study the properties of CIPP liners which have been operating under field conditions for nearly 30 years. Results of the study will provide insight into the longevity of in-service CIPP liners, thus enhancing confidence in current design procedures and specifications of these rehabilitation systems.