City of Morgan Hill Sewer System Master Plan 2017

x RM-P2 : Replace the 18-inch gravity sewer along Tennant Ave from Railroad Ave to Monterey Road. x RM-P3 : Replace the 10-inch gravity sewer along La Crosse Drive / Vineyard Boulevard from La Mar Drive to Monterey Road. 7.4 JOINT MORGAN HILL-GILROY SEWER TRUNK CAPACITY EVALUATION As part of this Master Plan, the Joint Morgan Hill-Gilroy Sewer Trunk (Joint Trunk) was evaluated for capacity adequacy. The Joint Trunk has historically had capacity constraints in the portion along California Avenue and Harding Avenue. Since the previous Master Plan, the City has surveyed the Joint Trunk, developed additional improvement alternatives to evaluate the feasibility of prioritizing construction, and constructed portions of a relief trunk. The Joint Relief Trunk (Relief Trunk) was identified in the 2002 Master Plan, and subsequent studies as a required improvement intended to mitigate existing capacity deficiencies and to service future growth. The City has constructed Relief Trunk along California Avenue, and south along Harding Avenue to Highland Avenue as a 30-inch parallel pipeline. The City is currently in the process of designing the remaining 30-inch Relief Trunk from Highland Avenue to the City of Gilroy ( Figure 7.4 ). 7.5 PIPELINE CONDITION ASSESSMENT As additional task added to the scope of the master plan, City staff requested Akel Engineering Group to utilize existing closed-circuit television (CCTV) data to assess the condition of the existing sewer system infrastructure. This section documents the findings and recommendations of the condition assessment. 7.5.1 Background and Purpose City staff have been proactively involved in the condition assessment of their pipelines, including performing CCTV, and rating those pipelines against the NASSCO Pipeline Assessment Certification Program (PACP). This rating system assesses pipelines based on observations from the CCTV, and scores them from 1 to 5 based on the criticality of the observations, with 5 being most critical. As such, City staff would like to prioritize improvement recommendations and costs in this master plan based on the physical condition of the sewer collection system. The pipelines that have been included in the CCTV, and which were reviewed as part of this condition assessment, are shown graphically on Figure 7.5 . 7.5.2 Condition Assessment Findings The condition assessment focused on documenting major structural defects (PACP Rating 4 or 5) and infiltration and inflow defects. Major structural defects can lead to costly pipeline failures, while infiltration and inflow defects may contribute to sanitary sewer overflows downstream.

August 2017

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City of Morgan Hill Sewer System Master Plan