You are here:
Results from a multi-year retrospective evaluation of rehabilitation technologies in North America
Citation:
Selvakumar, A., R. Sterling, AND S. Alam. Results from a multi-year retrospective evaluation of rehabilitation technologies in North America. Presented at International No-Dig 2015, Istanbul, TURKEY, September 28 - 30, 2015.
Impact/Purpose:
Deployment of trenchless pipe rehabilitation method has steadily increased over the past 40 years and has represented an increasing proportion of the annual expenditure on the nation’s water and sewer infrastructure. Until recently, despite the massive public investments in these technologies, there had been little to no quantitative data available to evaluate their expected performance. The biggest data gap has been identified as the prediction of the remaining asset life for the existing pipe and how long rehabilitation techniques can extend that life. Municipalities have expressed a strong desire for data on the current condition of previously installed systems to validate or correct the assumptions made at the time of rehabilitation.
Description:
Since 2009, the US Environmental Protection Agency has conducted various projects to support the development of rehabilitation technologies that can be used to maintain aging sewer and water systems in the USA. Since estimating the service life of rehabilitation technologies is a critical component of sewer asset management, an important part of this effort has been to conduct a retrospective study of the condition of selected relining technologies that have seen significant numbers of years in service. The retrospective study collected 25 wastewater pipe samples from 11 cities in North America. Testing of the various liners included thickness, annular gap, ovality, specific gravity, porosity, flexural strength, flexural modulus, tensile strength, tensile modulus, surface hardness, glass transition temperature, Raman spectroscopy, environmental stress crack resistance and pipe stiffness as appropriate to the liner type and condition. Cured-in-place pipe (CIPP) liners comprised 18 of the 25 samples. Other liners included were PVC fold-and-form, HDPE deform-reform and sliplining. The samples had been from 5 years to 34 years in service. This paper serves as a summary of the findings of the study and a gateway to the reports and papers that describe in full detail the testing procedures, sample-by-sample results, the aggregated results and the creation of a database to encourage more collection of retrospective data. A number of areas where the QA/QC of liner installation should improve were noted but, overall, the liners were in excellent condition and the physical test results indicated that these liners are expected to last their 50-year design life and probably well beyond
