In order to facilitate proper funding and management of its collection system, the District is required by the State Water Resources Control Board (SWRCB) under Order No. WQ 2022-0103-DWQ to develop and implement a system-specific Sewer System Management Plan (SSMP).  The SSMP must include a plan to identify and prioritize collection system deficiencies and implement actions to address each deficiency.  This program must include regular television inspection of sewer pipes and a system for ranking their condition.

In order to satisfy these requirements, the District has committed in its SSMP to embark upon a comprehensive Condition Assessment Program (Program) to clean and televise each and every pipeline in its 73-mile collection system.  The cleaning is a necessary preparation for the television inspection, and the televising records pipeline condition data pursuant to the National Association of Sewer Service Companies (NASSCO) standard rating system.  The Program includes manhole condition assessment inspections as well, also conducted pursuant to NASSCO.

Once it is gathered, the condition assessment data and NASSCO pipe ratings are fed into a computerized risk model which integrates that data with other factors that define each pipeline’s likelihood and consequence of failure.  These factors might include flow or pipe diameter; proximity to creeks, storm drainage, or other waterways; proximity to public facilities (e.g. hospitals, schools, police and fire stations); and major crossings (e.g. freeways, railroad tracks).  By doing this, the risk model calculates a relative score for each pipeline.  That score, when compared to the rest of the collection system, determines each pipeline’s overall risk of failure.  Once compiled, the risk of failure data is used to prioritize defective pipelines and scope out repair / rehabilitation / replacement projects.  The risk model supports preparation of the District’s capital improvement program updates.

The Condition Assessment Program’s complete cycle through the District’s entire collection system is occurring in three phases spread across five to six years, and is anticipated to be complete by the end of calendar year 2025.

During each phase, contractors responsible for televising and recording pipeline condition data via NASSCO ratings are also tasked with advising the District of any significantly defective sewer pipe that may require immediate attention.  Once identified, the District reviews such pipe to evaluate whether or not it poses a significant risk to human health or the environment, or has defects that may produce sewer spills due to the observed defective condition.  If either or both cases are true, the District’s short-term goal is to repair that pipe within 6 months of discovery and identification.

Once the Condition Assessment Program is complete, the District’s long-term goal is to design and construct multiple capital projects or phases spread over many years to repair, rehabilitate, or replace pipelines and manholes found to have defects during the Program.  The District plans to address all structural Grade 5 defects first, followed by structural Grade 4 defects afterwards.  It is impossible to provide exact schedule dates at present; however, each project or phase would be anticipated to last about two years on average.