Developing an Effective, Reasonable, and Defensible Sewer Rehabilitation and Replacement Plan – “Getting the Biggest Bang for your Buck”

In August 2004, the City of Los Angeles entered a Collection System Settlement Agreement (Agreement) with the United States Environmental Protection Agency. A key requirement of the Agreement was the development of a Rehabilitation and Replacement Report and Plan for the gravity sewer system. In 2006, the City used a set of analyses that incorporated SSO risk analysis, CCTV defect analysis, rehabilitation and replacement decision-making and projections to create a Rehabilitation and Replacement Report and Plan. The Plan documents the relationship of the renewal priority to sanitary sewer overflow reduction along with a projection of gravity sewer rehabilitation and replacement to be completed during the Agreement. This paper explains how to develop a reasonable and defensible forecast for sewer rehabilitation and replacement based on sewer overflow data, CCTV inspection data, a decision-making methodology, and projection approach. It describes the approach to focus capital projects on sewers having defects and factors known to increase SSOs and that cannot be effectively managed by a maintenance program. It also describes the streamlined process used to coordinate repair, rehabilitation, and replacement decision-making between operations, planning, and design groups.The City of Los Angeles developed a set of analytical methods to accurately and defensibly project collection system rehabilitation and replacement needs based on SSO analysis, CCTV defect analysis, decision-making techniques, and projection techniques. This paper will describe those techniques.