Building a Database for Life Cycle Performance Assessment of Water and Wastewater Rehabilitation Technologies

The deployment of trenchless pipe rehabilitation technologies steadily increased over the past 30 to 40 years and continue to represent a growing proportion of the approximately $25 billion annual expenditure on operations and maintenance of the nation’s water and wastewater infrastructure. Little formal or quantitative evaluation is available in the literature on whether these technologies are performing as expected and whether rehabilitation is indeed cost-effective compared to replacement. Therefore, the biggest data gap in asset management of existing pipeline systems involves the prediction of remaining asset life and how long rehabilitation techniques can extend that life. Municipalities have expressed a strong desire for some quantitative data on the current condition of previously installed systems to validate or correct the assumptions made at the time of rehabilitation. Since several of the major pipe lining techniques have now been in use for at least 15 years (some nearly 30 years in the U.S. and 40 years internationally), it was considered to be a suitable time to undertake such an investigation to assess whether the originally planned lifetime (typically assumed to be 50 years) is reasonable based on the current condition of the liner.The objective of this study was to create a national database of performance results for technologies used in the rehabilitation of gravity sewers, together with the means for interpreting the results through data mining techniques. Specimens from multiple lining techniques were collected from 25 in-service sites, and were subjected to a battery of physical tests, capturing quantitative experimental data as well as broader qualitative data from the agencies that participated in the study. The test results and supporting information were exported into a custom-developed Web-based database which enables the user to explore and interrogate the data using a series of statistical tools which were built into the software. Information provided includes trends over time of key mechanical properties, as well as establishing relationships among various properties, in an attempt to identify indicator(s) of degradation of the liner system. The paper describes the samples’ exhuming and testing program, web-based tool and presents key results from the data analysis. Developed as a “live” tool, the software is capable of re-generating the statistical analyses as new test data become available.