DEPARTMENT
Infrastructure Division
AGENDA NO.
7f
MEETING DATE
May 13, 2025
AGENDA ITEM
Public Utilities Commission
City and County of San Francisco
Calendar: Consent Calendar
Project Manager: Jimmy Leong
Approve Increases in Cost and Duration Contingencies for Contract No. HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement
Summary of Proposed
Commission Action:
Approve increases of $250,000 to the cost contingency and 50 calendar days to the duration contingency for Contract No. HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement with Sierra Mountain Construction, Inc., for a revised cost limit of $6,806,000, and a revised duration limit of 749 calendar days (approximately two years and one month), for additional costs and schedule impacts related to the installation of two new vent pipes to address unexpected cavitation during high- flow releases, as well as differing site conditions that may arise from rising river level during runoff season and potential issues with the as-built information.
Background: The San Francisco Public Utilities Commission (SFPUC) operates the O’Shaughnessy Dam in the Hetch Hetchy Reservoir on the Tuolumne River.
The Instream Flow Release Valve System at the O’Shaughnessy Dam includes a pair of valves that control water flow releases from Hetch Hetchy Reservoir to the Tuolumne River to achieve environmental benefits required by agreements with the Bureau of Land Management and the National Park Service.
The two previous 36-inch Larner-Johnson valves that regulated flow releases from the dam to the Tuolumne River were approximately 100 years old. In 2019, SFPUC staff inspected the condition of these valves and found severe damage. Staff curtailed flow releases from one of the valves since 2019 to avoid further damage and potential failure.
The objective of Contract No. HH-1011 is to replace and improve the existing release valves at O’Shaughnessy Dam to restore reliable and safe operation and maintain compliance with the environmental flow release requirements.
On June 13, 2023, by Resolution No. 23-0111, this Commission awarded Contract No. HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement, to Sierra Mountain Construction, Inc., in the amount of $5,960,000 and with a duration of 636 consecutive calendar days.
Scope of Contract: The contract work location is at O’Shaughnessy Dam in Yosemite National Park, Tuolumne County.
Agenda Title: HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement Commission Meeting Date: May 13, 2025
The contract work consists of:
• Remove and relocate existing stairways, ladders, and walkways to provide construction access near the location of the valve system. • Install two 36 -inch diameter knife gate valves and other devices to isolate and dewater the existing valve system from the 108-inch diameter diversion pipe.
• Install a new gantry crane to support the replacement and to perform future maintenance of the instream flow release valves. • Demolish and remove two existing 36-inch diameter Larner-Johnson needle valves and piping.
• Install two 48 -inch axial control valves and associated piping and concrete anchors.
• Install new electrical conduits and wiring.
• Furnish and install steel walkways and platforms.
Modifications to the
Contract:
Modification Nos. 1 to 7: Staff issued Modification Nos. 1 through 7, increasing the contract amount by $175,392.99, within the original 10% contingency, for equipment adjustments and measures necessary to maintain public safety and operations, for a total contract amount of $6,135,392.99, with no change to the contract duration.
Recommended Increase to Cost & Duration Contingencies:
Staff recommends the Commission approve an increase of $250,000 to the existing cost contingency, for a revised cost limit of $6,806,000, and an increase of 50 calendar days
to the existing duration contingency, for a
revised duration limit of 749 consecutive calendar days (approximately two years and a month), for additional costs and schedule impacts related to the installation of two new vent pipes to address unexpected cavitation during high-flow releases, as well as differing site conditions that may arise from rising river levels during the runoff season, or potential issues with as -built information.
Funding and Costs: Funding Source: Hetch Hetchy Capital Improvement Program, Project No. 10032903, O’Shaughnessy Dam Outlet Works Phase 1
Original Contract Amount: $5,960,000
Original 10% Cost Contingency: $596,000
Approved Increase in Cost Contingency: $0
Modified Increases to Contract Amount: $175,392.99
Total Current Contract Amount: $6,135,392.99
Remaining Cost Contingency: $420,607.01
Recommended Additional Cost Contingency: $250,000
Total Proposed Cost Limit: $6,806,000
Schedule: Notice-to-Proceed Date: August 28, 2023
Original Contract Duration: 636 consecutive calendar days Original 10% Duration Contingency: 63 calendar days
Agenda Title: HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement Commission Meeting Date: May 13, 2025
Modified Increase to Duration Contingency: 0 calendar days Total Current Contract Duration: 636
Remaining Duration Contingency: 63 calendar days
Requested Additional Duration Contingency: 50 calendar days Total Proposed Duration Limit: 749 consecutive calendar days
Environmental
Review:
On December 2, 2022, the San Francisco Planning Department determined the Project to be categorically exempt from environmental review under the CEQA Guidelines section 15301, Class 1 (Existing Facilities) and section 15302, Class 2 (Replacement or Reconstruction) under Case No. 2022- 004533ENV. The work under this modification is within the scope of the project authorized under the exemption.
The exemption determination can be found here:
https://sfpuc.sharefile.com/d-s423b4c77a11143fb826fafc2ce30a0cc
Local Business
Enterprise Utilization
and Non-
Discrimination in
Contracting:
The Contract Monitoring Division established a n 8% Local Business Enterprise (LBE) subcontracting requirement for this contract. Sierra Mountain Construction, Inc., committed to a n 11.47% LBE subcontractor participation with its bid submittal.
Agenda Title: HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement Commission Meeting Date: May 13, 2025
PUBLIC UTILITIES COMMISSION
City and County of San Francisco
RESOLUTION NO.
WHEREAS, The San Francisco Public Utilities Commission (SFPUC) operates the O’Shaughnessy Dam in Yosemite National Park, Tuolumne County. As a part of Dam operations, the instream flow release valve system provides controlled environmental flow releases from Hetch Hetchy Reservoir, as required by agreements with the United States Bureau of Land Management and the National Park Service; and
WHEREAS, On June 13, 2023, by Resolution No. 23-0111, the Commission awarded Contract No. HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement to Sierra Mountain Construction, Inc.; and
WHEREAS, The original contract amount was for $5,960,000 and the original contract duration was 636 consecutive calendar days; and
WHEREAS, The contract Notice-to-Proceed date was August 28, 2023; and
WHEREAS, Staff issued Modification Nos. 1-7, increasing the contract amount by $175,392.99, within the original 10% contingency, for equipment adjustments and measures necessary to maintain public safety and operations , for a total contract amount of $6,135,392.99, with no change to the contract duration; and
WHEREAS, Staff recommends an i ncrease of $250,000 to the cost contingency and an increase of 50 calendar days to the duration contingency, for additional costs and schedule impacts related to the installation of two new vent pipes to address unexpected cavitation during high-flow releases, as well as differing site conditions that may arise from rising river level during runoff season, and potential issues with the as-built information; and
WHEREAS, The Contract Monitoring D ivision established a Local Business Enterprise (LBE) subcontracting participation of 8% for this contract, and the contractor committed to a n LBE subcontractor participation of 11.47% with its bid submittal; and
WHEREAS, On December 2, 2022, the San Francisco Planning Department determined the Project to be categorically exempt from environmental review under the CEQA Guidelines section 15301, Class 1 (Existing Facilities) and section 15302, Class 2 (Replacement or Reconstruction) under Case No. 2022-004533ENV; and the work under this modification is within the scope of the project authorized under the exemption; and
WHEREAS, Funds are available from Project No. 10032903, O’Shaughnessy Dam Outlet Works Phase 1; now, therefore, be it
RESOLVED, That this Commission hereby a pproves an increase of $ 250,000 to the existing cost contingency and an increase of 50 calendar days to the existing duration contingency, for Hetch Hetchy Capital Improvement Program funded Contract No. HH-1011, O’Shaughnessy Dam Instream Flow Release Valve Replacement , for a total cost contingency amount of up to $670,607.01 and a total duration contingency of 113 calendar days; and be it FURTHER RESOLVED, That this Commission hereby authorizes the General Manager, or the General Manager’s designee, to consider, and, if appropriate, to approve any future modifications to the contract amount for a total contract amount of up to $6,806,000, and a total contract duration of up to 749 consecutive calendar days.
I hereby certify that the foregoing resolution was adopted by the San Francisco Public Utilities Commission at its meeting of May 13, 2025.
Director of Commission Affairs
San Francisco Public Utilities Commission