The San Joaquin Pipeline Valve and Safe Entry Improvement Project involves the three parallel transmission pipelines that stretch approximately 48-miles across the San Joaquin Valley from Oakdale Portal to Tesla Portal, with a partial fourth pipeline consisting of a 6.4-mile Eastern Segment and an 11-mile Western Segment. The four pipelines were built between 1932 and 2012 and range from 56- to 79.5-inches in diameter. As part of the Water System Improvement Program, valve vaults were constructed along the San Joaquin Pipeline System at various locations to increase operational flexibility and the overall reliability of the San Joaquin Pipeline System.
Since the commissioning of the valve vaults staff have concerns about the valves’ ability to sufficiently operate during certain scenarios. These include, 1) The valves may fail due to pressure surges under certain conditions, 2) cannot establish double isolation and bleed configurations to protect workers when maintaining the pipes, and 3) the valves may not be adequately rated for hydrostatic head (the pressure of the water in the pipeline flowing by gravity).
In order to achieve the safety and access goals, the scope is to: install a surge shaft upstream of Tesla Treatment Facility; install new double isolation and bleed valves at all locations where major upgrades and construction are required; and retain single isolation where no upgrades are needed.
There are four primary locations where major upgrades and construction are required: Emery, Roselle, Pelican, and Tesla.
The project is part of a larger Hetchy Capital Improvement Program (HCIP), a multi-year capital program to upgrade or improve water conveyance, water storage, and power generation facilities in the Sierra Nevada portion of the Hetch Hetchy Regional Water System.