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SFPUC says reservoirs improved, outlines Mountain Tunnel contingency and selects engineering firm
Summary
At its Oct. 27 meeting the San Francisco Public Utilities Commission reported stronger reservoir storage and the successful Lower Cherry Aqueduct test, discussed contingency plans for a potential Mountain Tunnel outage, and approved hiring Macmillan Jacobs Associates for up to $21 million to lead condition assessment and repairs.
The San Francisco Public Utilities Commission on Oct. 27 received an update on city water supplies and moved to secure engineering support for Mountain Tunnel work.
Steve Ritchie, Assistant General Manager for Water, told commissioners Hetch Hetchy Reservoir was at about 73% of capacity and the Water Bank had increased to roughly 190,000 acre‑feet (staff expects up to about 200,000 acre‑feet this fall). He said Lake Eleanor had been temporarily drawn down to roughly 20 acre‑feet to permit valve and connection work. After a summer delivery peak near 205 million gallons per day (MGD), system deliveries were about 195 MGD last week, Ritchie said.
Ritchie described a full‑scale test of the Lower Cherry Aqueduct that began Oct. 10 and delivered roughly 500,000,000 gallons to customers. The test wound down when turbidity spiked and staff returned filtered supplies to Hetch Hetchy on Nov. 3, earlier than the originally targeted Nov. 12, he said. The test, Ritchie added, identified a few small issues but was successful at demonstrating the system’s capability.
Public comments and a commission exchange focused on Mountain Tunnel risks and regional contingency planning. A public speaker urging prompt action summarized a five‑part Mountain Tunnel plan—improved access, asset acquisition, routine inspection and repair, a bypass concept, and a regional emergency water‑supply plan to cover an extended outage. The speaker and commissioners pressed staff for a timeline and for near‑term actions to reduce the risk of a supply shortfall.
Ritchie said staff had finalized a technical memo modeling outage scenarios. He reported that with source shifting and demand management the utility could reliably cover an outage of about 90 days and could approach roughly 180 days with additional measures; an outage of about 270 days would require significant additional actions. He said staff is meeting with member agencies and individual large customers to identify source‑shifting and demand‑management options.
Separately, the commission approved Item 11 to select Macmillan Jacobs Associates under agreement CS249 for professional services not to exceed $21,000,000 and with a potential duration up to 10 years. Staff described a phased approach: a condition assessment (the last comprehensive assessment dated to 2008), targeted interim repairs, and then a decision in the following year on whether to continue repairs or pursue a tunnel alternative. Commissioners confirmed the firm would be the engineer of record for the selected alternative and assist with interim repairs.
The commission approved the selection by vote and moved on to other agenda items.
