DEPARTMENT Infrastructure Division
AGENDA NO.
7b
MEETING DATE
January 13, 2026
AGENDA ITEM
Public Utilities Commission
City and County of San Francisco
Calendar: Consent Calendar
Project Manager: Jimmy Leong
Accept Closeout, Approve Modification No. 1 (Final) , and Authorize Final Payment for Contract No. DB-135, O’Shaughnessy Dam New Bulkhead System
Summary of Proposed
Commission Action:
Accept work performed by Alltech Engineering Corp , under Contract No.
DB-135, O’Shaughnessy Dam New Bulkhead System ; approve Modification No. 1 (Final), decreasing the contract amount by $3,497,149, for a total contract amount of $6,359,851, with no change to the contract duration, due to lower-than-expected bid prices of different trade packages, and unused allowances, reserves, and contingencies; and authorize final payment to the contractor.
Background: The San Francisco Public Utilities Commission (SFPUC) Water Enterprise operates the O’Shaughnessy Dam, a critical component of the SFPUC Hetch Hetchy water system. The dam is located 140 miles east of San Francisco and 60 miles east of Sonora in Yosemite National Park, Tuolumne County. The City and County of San Francisco (City) constructed the concrete dam to create the Hetch Hetchy Reservoir. The City constructed the dam in two stages beginning in August 1919. In the first stage, the City completed the dam in April 1923 at a structural height of 344.5 feet (Elevation 3726.5).
Beginning in April 1935, the City raised the O’Shaughnessy Dam by 85.5 feet to the current final height of 430
feet (Elevation 3812 feet). The
additional height provided an increase of 143,885 acre -feet of storage and a total current capacity of 360,360 acre-feet. The dam includes a side channel spillway located at the left abutment of the dam. The outlet system includes large diameter slide gates, needle valves, and butterfly valves. Water from the reservoir flows through twelve inlets along the upstream face of the dam and then through the outlet structure via these gates and valves. The City installed most of these gates and valves when building the initial stage of the dam in 1923; they are 100 years old and require frequent inspection and maintenance to assure continuous operability. The twelve inlets along the upstream face of the dam were initially able to be isolated by a bulkhead system. This bulkhead system ha d fallen into disrepair and need ed to be
replaced.
This project involved the design and construction of a new bulkhead system to provide reliable and safe isolation of existing gates and valves in the dam for safe worker entry for maintenance, repairs, and improvements.
Agenda Title: DB-135, O’Shaughnessy Dam New Bulkhead System Commission Meeting Date: January 13, 2026
On June 13, 2023 , by Resolution No. 23-0109, this Commission awarded Contract No. DB -135, O’Shaughnessy Dam New Bulkhead System , to Alltech Engineering Corp. The original contract amount was $9,857,000 and the original contract duration was 670 consecutive calendar days.
Scope of Contract: The contract work location was at O’Shaughnessy Dam in Yosemite National Park, Tuolumne County.
The contract work consisted of:
• Underwater investigation and collection of design data; • Development of technical requirements in conformance with the project performance criteria;
• Design and preparation of plans and specifications for the new bulkhead system;
• Procurement of subcontractor trade packages;
• Manufacture of new bulkheads;
• Removal of rust and tubercles and restoration of the cast-iron sealing surface at the inlet; and,
• Installation and testing, and removal (for later reinstallation), of the new bulkheads.
Modification to the
Contract:
Proposed Modification No. 1 (Final): Staff recommends Commission authorization to de crease the contract amount by $3,497,149 due to lower - than-expected bid prices of different trade packages, unused allowances, reserves, and contingencies , for a new total contract amount of $6,359,850.33, with no change to the contract duration.
Funding and Costs: Funding Source: Hetch Hetchy Capital Improvement Program, Project No. 10032903, O’Shaughnessy Dam Outlet Works Phase 1
Original Contract Amount: $9,857,000
Original 10% Cost Contingency: $985,700
Approved Increase to Cost Contingency: $0
Modified Increases to Contract Amount: $0
Total Current Contract Amount: $9,857,000
Current Cost Contingency: $985,700
[Proposed] Modification No. 1 (Final) Amount: ($3,497,149) Total [Proposed] Contract Amount: $6,359,851
Schedule: Notice-to-Proceed Date: September 1, 2023
Original Contract Duration: 670 calendar days
Original 10% Duration Contingency: 67 calendar days
Approved Increase to Duration Contingency: 0 calendar days Modified Increases to Contract Duration: 0 calendar days Total Current Contract Duration: 670 consecutive calendar days Agenda Title: DB-135, O’Shaughnessy Dam New Bulkhead System Commission Meeting Date: January 13, 2026
Current Duration Contingency: 67 calendar days
[Proposed] Modification No. 1 (Final) Duration: 0 calendar days Total [Proposed] Contract Duration: 670 calendar days
Local Business
Enterprise Utilization
and Non-
Discrimination in
Contracting:
The Contract Monitoring Division established a 3% Local Business Enterprise (LBE) subcontracting requirement for the Design (Pre - Construction) Phase and 3% Local Business Enterprise (LBE) subcontracting requirement for the Construction Phase of
this contract. The contractor
committed to a 3.4% LBE subcontractor participation for Design (Pre - Construction) Phase and 3% Local Business Enterprise (LBE) subcontractor participation for the Construction Phase with its bid submittal. The Contract Monitoring Divisio n determined the contractor complied with its Local Business Enterprise subcontracting requirement by achieving a final LBE subcontractor participation of 3.05% for the Design (Pre-Construction) Phase and 10.34% for the Construction Phase.
Attachment(s): 1. Contract Monitoring Division Memorandum Agenda Title: DB-135, O’Shaughnessy Dam New Bulkhead System Commission Meeting Date: January 13, 2026
PUBLIC UTILITIES COMMISSION
City and County of San Francisco
RESOLUTION NO.
WHEREAS, The San Francisco Public Utilities Commission (SFPUC) is responsible for the operation of O’Shaughnessy Dam in Yosemite National Park, Tuolumne County, a critical component of the SFPUC Hetch Hetchy water system; and
WHEREAS, The O’Shaughnessy Dam required a new bulkhead system to provide reliable and safe isolation of existing gates and valves for maintenance, repairs, and improvements; and
WHEREAS, On June 13, 2023, by Resolution No. 23- 0109, the Commission awarded Contract No. DB-135, O’Shaughnessy Dam New Bulkhead System to Alltech Engineering Corp; and
WHEREAS, The original contract amount was for $9,857,000 and the original contract duration was 670 consecutive calendar days; and
WHEREAS, The contract Notice-to-Proceed date was September 1, 2023; and
WHEREAS, Staff recommends that the Commission approve Modification No. 1 (Final) to decrease the contract amount by $3,497,149 for a total c ontract amount of $6,359,851 to complete the work scope including design and provision of the new bulkhead system; and removal of rust and tubercles of the cast iron inlet surface, with no change to the contract duration; and
WHEREAS, Alltech Engineering Corp has completed the work scope under Contract DB- 135, O’Shaughnessy Dam New Bulkhead System; and
WHEREAS, The Contract Monitoring Division determined that the contractor complied with the established Local Business Enterprise subcontracting requirement of 3.00% for this contract by achieving a final Local Business Enterprise subcontractor participation of 3.05% for the Design (Pre-Construction) Phase and 10.34% for the Construction Phase; and
WHEREAS, Funds are available from Project No. 10032903, O’Shaughnessy Dam New Bulkhead System, now, therefore, be it
RESOLVED, That this Commission hereby accepts the work performed by Alltech Engineering Corp., under Contract No. DB -135, O’Shaughnessy Dam New Bulkhead System ; approves Modification No. 1 (Final), decreasing the contract amount by $3,497,149, for a total contract amount of $6,359,851, with no change to the contract duration ; and authorizes final payment to the contractor.
I hereby certify that the foregoing resolution was adopted by the San Francisco Public Utilities Commission at its meeting of January 13, 2026.
Director of Commission Affairs
San Francisco Public Utilities Commission