DEPARTMENT
Infrastructure Division
AGENDA NO.
14 MEETING DATE
December 9, 2025
AGENDA ITEM
Public Utilities Commission
City and County of San Francisco
Calendar: Regular Calendar
Project Manager: Jimmy Leong
Approve Increases to the Cost and Duration Contingencies for Contract No. HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements
Summary of Proposed
Commission Action:
Approve an increase of $1,000,000 to the cost contingency and an increase of 382 calendar days to the duration contingency for Contract No. HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements , with Sierra Mountain Construction, Inc., for a revised cost limit of $6,814,550 and a revised duration limit of 7 78 calendar days (approximately two years and two months), to address modifications to the ladder-well platforms necessary to conform to site conditions and additional crack sealing work in supply wells to reduce leakage and thereby improve safe access within the dam.
Background: The San Francisco Public Utilities Commission (SFPUC ) Water Enterprise is responsible for operating O’Shaughnessy Dam, which is located 140 miles east of the City and County of San Francisco, in Yosemite National Park, Tuolumne County. Initially constructed in the 1920s to impound water within Hetch Hetchy Reservoir, O’Shaughnessy Dam is the primary structure of the Hetch Hetchy system, which
includes the Hetch Hetchy Reservoir, the
Canyon Power Tunnel, and the Robert C. Kirkwood Powerhouse. The dam, a concrete curved gravity structure, is located on the Tuolumne River. In 1938, the dam was raised to its present-day height.
The objective of this project is to improve drainage and safe access within the dam.
On August 13, 2024, by Resolution No. 24-0166, this C ommission awarded Contract No. HH -1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements, to Sierra Mountain Construction, Inc., in the amount of $5,285,955 and with a term of 360 consecutive calendar days.
Scope of Contract: The contract work location is at O’Shaughnessy Dam, located in Yosemite National Park, Tuolumne County.
The contract work consists of:
• Selective concrete demolition, including removal and disposal, • Diversion Tunnel access improvements,
• Ladder well platforms replacements,
• Drain cleaning, and
Agenda Title: HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements Commission Meeting Date: December 9, 2025
• Watertight door replacement.
Modifications to the
Contract:
Modification No 1: Effective September 23, 2025, the SFPUC modified the contract within the initial cost contingency, and increased the contract amount by $5,996 to remove additional concrete not indicated on the contract drawings but necessary to improve safe access for a total contract amount of $5,291,951.
Recommended Increase to Cost and Duration Contingency:
Staff recommends the Commission approve an increase of $1,000,000 to the existing cost contingency, for a revised cost limit of $6,814,550, and an increase of 382 calendar days to the existing duration contingency, for a revised duration limit of 778 calendar days (approximately two years and two months), to address modifications to ladder well platforms to conform to site conditions and additional crack sealing work in the supply wells to reduce leakage and thereby improve safe access within the dam.
Funding and Costs: Funding Source: Hetch Hetchy Capital Improvement Program Project No. 10032903, O’Shaughnessy Dam Outlet Works Phase 1 Original Contract Award Amount: $5,285,955
Original 10% Cost Contingency: $528,595
Approved Increase in Cost Contingency: $0
Modified Increase to Contract Amount: $5,996
Total Current Contract Amount: $5,291,951
Remaining Cost Contingency: $522,599
Requested Additional Cost Contingency: $1,000,000
[Proposed] Total Revised Cost Limit: $6,814,550
Schedule: Notice-to-Proceed Date: November 12, 2024
Original Contract Duration: 360 consecutive calendar days Original 10% Duration Contingency: 36 calendar days
Modified Increase to Contract Duration: 0 calendar days Total Current Contract Duration: 360 consecutive calendar days Current Duration Contingency: 36 calendar days
Requested Additional Duration Contingency: 382 calendar days [Proposed] Total Revised Duration Limit: 778 calendar days
Environmental
Review:
On July 16, 2020 , the San Francisco Planning Department determined the Project to be categorically exempt from environmental review under the California Environmental Quality Act Guidelines section 15301, Class 1 (Existing Facilities) under Case Number 2020-004917ENV.
The work under this modification is within the scope of the project authorized under this categorical exemption.
The exemption can be found here:
Agenda Title: HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements Commission Meeting Date: December 9, 2025
https://sfpuc.sharefile.com/public/share/web-
sbcc7db0171d842e2aba813f6a0050c61
Local Business
Enterprise Utilization
and Non-
Discrimination in
Contracting:
The Contract Monitoring Division established a 10% Local Business Enterprise (LBE) subcontracting requirement for this contract. Sierra Mountain Construction, Inc., committed to a n 11.39% LBE subcontractor participation as stated on their bid submittal, and this remains unchanged.
Agenda Title: HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements Commission Meeting Date: December 9, 2025
PUBLIC UTILITIES COMMISSION
City and County of San Francisco
RESOLUTION NO.
WHEREAS, The San Francisco Public Utilities Commission (SFPUC) Water Enterprise is responsible for operating O’Shaughnessy Dam in Yosemite National Park; and
WHEREAS, On August 13, 2024, by Resolution No. 24-0166, the Commission awarded Contract No. HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements to Sierra Mountain Construction, Inc.; and
WHEREAS, The original contract amount was for $5,285,955 and the original contract duration was 360 consecutive calendar days; and
WHEREAS, The contract Notice-to-Proceed date was November 12, 2024; and
WHEREAS, Staff issued Modification No. 1, increasing the contract amount by $5,996, within the original 10% contingency, to remove additional concrete which was necessary to maintain safe access within the dam, for a total contract amount of $5,291,951, with no change to the contract duration; and
WHEREAS, Staff recommends an increase of $1,000,000 to the cost contingency and an increase of 382 calendar days to the duration contingency, for a revised cost limit of $6,814,550 and a revised duration limit of 778 calendar days, to allow the contractor to modify the proposed ladder-well platforms to conform to site conditions and to complete additional crack sealing work in the supply wells to reduce leakage and thereby improve safe access within the dam; and
WHEREAS, The Contract Monitoring Division established a Local Business Enterprise (LBE) subcontracting participation of 10% for this contract, the contractor committed to an LBE subcontractor participation of 11.39% with its bid submittal, and this amount remains unchanged; and
WHEREAS, On July 16, 2020, the San Francisco Planning Department determined the Project to be categorically exempt from environmental review under the California Environmental Quality Act Guidelines section 15301, Class 1 (Existing Facilities) under Case Number 2020 - 004917ENV, and the work under this Modification is within the scope of the project authorized under the categorical 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 $1,000,000 to the existing cost contingency and an increase of 382 calendar days to the existing duration contingency for Contract No. HH-1015, O’Shaughnessy Dam Drainage and Miscellaneous Improvements, for a total cost contingency of $1,528,595 and a total duration contingency of 418 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 modifications to the contract, up to a total cost limit of $6,814,550 and a total duration limit of 778 calendar days.
I hereby certify that the foregoing resolution was adopted by the San Francisco Public Utilities Commission at its meeting of December 9, 2025.
Director of Commission Affairs
San Francisco Public Utilities Commission