WESIP progress: Calaveras stabilization, Irvington tunnel nearing breakthrough, Bay Tunnel lining advances
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Summary
Resive Director Julie Labonte updated the commission on Water System Improvement Program activity: seismic and slope work at Calaveras, nearly complete Irvington tunnel boring with about 600 feet to go and continued progress on Bay Tunnel inner pipe lining (2 of 5 miles welded).
Julie Labonte briefed the commission on key WESIP projects and field conditions observed during recent work and the Rim Fire response.
On Calaveras, Labonte said crews are stabilizing Observation Hill and have identified additional tectonic features that require reinforcement; the team expects to have a clearer estimate of cost and schedule impacts within a month and is using contingency funds for the immediate work.
At Irvington, engineers are using conventional tunneling methods because of squeezing-ground conditions; Labonte reported production at about 100–150 feet per week with roughly 600 feet remaining and an expected final breakthrough in October. "We only have 600 feet left to mine, before hold through. Final hold through is expected in October," she said.
On the Bay Tunnel project, Labonte said inner pipelining installation has progressed well and final welding has been completed on approximately 2 miles of the planned 5-mile inner line; grouting between the inner and outer linings is scheduled to begin shortly.
Labonte praised recent resilience investments, noting that improvements made under WESIP increased operational flexibility during the Rim Fire emergency and helped the utility manage shifting supply and treatment demands. She closed by offering to return with further analysis of geotechnical findings and schedule impacts once additional investigation is complete.