LESSONS LEARNED IN IMPLEMENTING A COMPREHENSIVE SEWER INSPECTION PROGRAM IN THE DIGITAL AGE

County Sanitation District 1 (CSD-1, District) owns and operates a 2,500-mile wastewater collection system serving the Sacramento, California, urban area. In 1998, CSD-1 initiated a program to assess the physical condition of its sewer system and plan for its long-term rehabilitation needs. As the first step in prioritizing sewers for inspection and rehabilitation, the District developed a Predictive Pipe Condition Model to predict the condition of the sewers and estimate long-term rehabilitation costs. Using the model, all pipes in the system were scored based on their predicted condition. Pipes with the highest (worst) scores were identified for the initial inspection work under the condition assessment program. The first project under the new program, called “Rehabilitation Project 2, ” was initiated in June 2001. Two consultant teams were hired to perform condition assessment of the approximately 450,000 feet of sewer pipes with the highest predictive model scores. CSD-1 and the project consultants developed a comprehensive Work Plan to set the stage for the project, as well as serve as the framework for the long-term program. One of the key objectives of the project was to develop procedures and standards to collect inspection data in all digital format.The project Work Plan included the following elements:A formal public outreach programHealth and safety procedures and notification protocolsA manhole inspection programPreparation of a TV Inspection ManualDevelopment of specifications for digital video and data deliverablesA formal training session for inspection workers on the TVI procedures and codesDespite the extensive efforts put into the up-front planning, the project has encountered some “bumps in the road” along the way. Some of these included:Scheduling and coordination of the field efforts was made more difficult because theinspected segments were scattered throughout the service area.Different TVI software were used by different TVI contractors, making it harder to enforce standard data reporting formats and procedures.Some TVI contractors had limited experience using digital TVI data collection tools.Some of the TVI software had limitations that had not been well understood.File naming and some observation coding formats adopted by the District were difficult to implement with the off-the-shelf TVI software used by the contractors.The quality of some of the digital video images, particularly for large diameter reinforced concrete pipe, was not as good as expected.TVI contractors were unaccustomed to and not well equipped to manage the large volume of digital data collected, and to perform needed quality assurance/quality control of the data.CSD-1 and its consultants and their inspection contractors have learned from these issues and adapted as the project has progressed. Ultimately, CSD-1 plans to inspect 1.5 million feet of sewer pipe each year, using a combination of outside contractors and in-house forces. CSD-1 believes that these lessons will serve them well as they continue their long-term efforts to manage and improve their wastewater collection system. This paper describes in more detail the procedures and methods used in the condition assessment program and the lessons learned during the process.