The Lake Tahoe Basin Wastewater Infrastructure Partnership (Partnership) involves the U.S. Army Corps of Engineers and eight wastewater agencies that maintain wastewater collection systems in the Basin. The Partnership has undertaken a number of initiatives to reduce the risk of sewer leaks or overflows that could degrade the water quality of Lake Tahoe. These initiatives include the development of inspection and condition assessment standards, a decision algorithm for improvement project identification, a project prioritization process, and a project database to manage information related to improvement projects. This paper discusses the development and implementation of these tools by the Basin's wastewater agencies. The initiatives are helping the agencies work together to maintain Lake Tahoe's legendary water quality.

The City of San Diego's Metropolitan Wastewater Department (MWWD) is currently working on several initiatives to reduce the frequency and severity of sanitary sewer overflows (SSO's). These initiatives include an accelerated cleaning program for all 3,000 miles of pipe in the system, a closed-circuit television (CCTV) inspection program, and a capital program to replace or rehabilitate 60 miles of sewer per year. All of these initiatives are being aided by MWWD's implementation of Geographic Information System (GIS) tools. This paper describes some of the tools that have helped MWWD to plan and manage their spill reduction initiatives.

The City of San Diego's Metropolitan Wastewater Department is responsible for maintaining approximately 3,000 miles of sewer pipe. As part of an initiative to reduce sanitary sewer overflows, the City was required to estimate the remaining useful life of its approximately 70,000 pipe segments. Through a series of workshops, the City developed an algorithm that incorporated the available information for each pipe segment. Existing databases contained information on maintenance history, occurrence of overflows, inspection and condition assessment results, and proximity to sensitive locations. An automated algorithm was developed to retrieve information from these databases and calculate an expected remaining life for each pipe segment. Summaries of the results are being presented to regulatory agencies and are being used to estimate long-term renewal and replacement needs. This paper discusses the process the City developed for estimating remaining life, including the input databases and the calculation procedures. The paper also discusses modifications and enhancements that the City is considering to provide better planning information for long-term management of the system.

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