Analysis of risk management methods used in trenchless renewal decision making

The substandard condition of wastewater systems in the US, accompanied by the lack of financial resources for renewal are hindering adequate operation and maintenance of deficient sewer systems. Information about current and future pipe condition, as well as information about the impact of possible pipe failures are an integral part of an efficient asset management program and can help stakeholders make the best decisions to prioritize rehabilitation and/or replacement projects. Typically, pipes in the worst structural conditions are prioritized and budgeted within the capital improvement project planning. To be able to predict future pipe conditions, many methods have been developed and successfully implemented that incorporate pipe inspection data to predict the future state of these assets. Additionally, methodologies exist for determining the consequences of pipe failures economically, socially, and environmentally. These methods have been incorporated into decision support systems (DSS) that help utility managers determine when to rehabilitate or replace their assets. DSS for trenchless pipe renewal allow utility managers to determine the most suitable method to renew their assets, given known defects in the pipe. The aim of this paper is to provide a review of risk management methods that allow pipeline managers to estimate likelihood of failure and quantify consequence of failure of sewer pipes. Additionally, an updated review of existing DSS for trenchless pipe rehabilitation is presented and analyzed. Finally, recommendations are made to improve existing methods to make the risk management process for trenchless rehabilitation decision making more efficient and practical.