DESCRIPTION: 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. 

Once it is gathered, the condition assessment data and NASSCO 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 first complete cycle through the District’s entire collection system is occurring in three phases spread across five to six years.  The Program includes manhole condition assessment inspections as well, also conducted pursuant to NASSCO.

Phase 2 cleaned approximately 95,374 linear feet (~18.0 miles) and televised approximately 91,367 linear feet (~17.3 miles) of sewer pipe and conducted 514 manhole inspections.

JUSTIFICATION:  Condition assessment should be conducted continually to maintain an ongoing understanding of the state of the District’s collection system infrastructure, and to become a reference point for capital planning, project prioritizing, annual budgeting, and sewer service charge rate setting.  The findings and recommendations of this Program will form the basis of future collection system improvements capital projects.

TOTAL PHASE 1 COST:  $467,511.14

PHASE 1 COMPLETION:  June 2021