To: Board of Supervisors
Department or Agency Name(s): Sonoma County Public Infrastructure
Staff Name and Phone Number: Johannes J. Hoevertsz, 707-565-2550
Vote Requirement: Majority
Supervisorial District(s): Fifth
Title:
Title
Wohler Road Bridge over the Russian River Seismic Retrofit Project, C01136, Construction Contract Change Order
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Recommended Action:
Recommended action
Approve and authorize the Director of Sonoma Public Infrastructure to execute a construction contract change order with Ghilotti Construction Company, Inc. in an amount not to exceed $510,000 for environmental compliance work associated the Wohler Road Bridge Seismic Retrofit Project.
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Executive Summary:
The Department of Public Infrastructure (SPI) requests Board approval to authorize the Director of SPI to execute a construction contract change order with Ghilotti Construction Company, Inc. in an amount not to exceed $510,000 for the Wohler Road Bridge over the Russian River Seismic Retrofit Project (C01136). This change order is necessary to comply with environmental permitting during a third construction season occurring in 2026. This change order will not change the total, not-to-exceed contract amount of $26,232,083. The cost of these additional measures is estimated at up to $510,000 which is available under the original contract contingency amount but exceeds the Director's delegated contract authority and requires Board approval.
Discussion:
The Wohler Road Bridge Seismic Retrofit Project (Project) is the largest and most complex bridge project undertaken by the County of Sonoma. The Project retrofits the existing historical, seismically deficient one-lane Wohler Road Bridge (Bridge Number 20C-155), with a new lightweight concrete deck, seismic isolation bearings, steel truss reinforcement, and foundation reinforcement. This project is a seismic retrofit intended to strengthen critical components of the existing bridge rather than replace the structure in its entirety. The current project is limited to addressing the identified seismic vulnerabilities and has a complex challenge of fitting new seismic components to aging infrastructure.
On February 6, 2024, the Board awarded a construction contract for the Project to Ghilotti Construction Company, Inc. in the amount of $17,994,621 and authorized a 10% contingency in the amount of $1,799,462, for a total not-to-exceed contract amount of $19,794,083.18.
Since construction began, the Board has approved several increases to the contract amount to address unforeseen conditions and necessary changes to the work. On December 16, 2025, the Board authorized the Director of Sonoma Public Infrastructure to execute a construction contract change order for up to $2,300,000 due to differing site conditions and a County initiated acceleration in the construction schedule. On March 24, 2026, the Board increased the contract amount by an additional $3,000,000 to fund Contract Change Order (CCO) fourteen (14) for pier foundation method changes and CCO fifteen (15) for dewatering method changes. On April 28, 2026, the Board again increased the contract amount by $3,438,000, for a new total contract amount, including all contingency, of $26,232,083, to fund CCO sixteen (16) for scaffolding use in 2026 and CCO nineteen (19) for superstructure plan changes.
Because construction has extended into a third construction season in 2026, additional biological monitoring and bird protection and exclusion measures are required to maintain compliance with the Project's environmental permits and the Migratory Bird Treaty Act of 1918. The cost of these additional measures is estimated at up to $510,000 which is available under the original contract contingency amount but exceeds the Director's delegated contract authority and requires Board approval.
SPI now requests that the Board authorize the Director of Sonoma Public Infrastructure to execute a construction contract change order in an amount not to exceed $510,000 for the required biological monitoring and bird protection and exclusion measures. Funding for the construction project is 88.53% Federal Highways Administration (FHWA) funds administered by Caltrans. SPI has coordinated with Caltrans regarding the additional project costs and has received assurance the costs are eligible for federal reimbursement. SPI has submitted a request for reimbursement for the applicable contract change order costs.
Strategic Plan:
This item directly supports the County’s Five-year Strategic Plan and is aligned with the following pillar, goal, and objective.
Pillar: Resilient Infrastructure
Goal: Goal 3: Continue to invest in critical road, bridge, bicycle, and pedestrian infrastructure.
Objective: Objective 1: Continue to maintain road segments, including designated turnouts where feasible, increase efforts on vegetation removal and drainage features, and improve pavement conditions in neighborhoods.
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
4/28/2026: Board authorized SPI Director to execute construction contract change order for superstructure plan changes and increased the construction contract in the amount of $3,438,000.
3/24/26: Board authorized SPI Director to execute construction contract change order for dewatering changes in the amount of $665,500 and increased the construction contract by $3,000,000.
12/16/2025: Board authorized SPI Director to execute construction contract change order for differing site conditions and acceleration in an amount up to $2,300,000.
2/06/2024: Board awarded project construction contract to Ghilotti Construction Company, Inc.
12/07/2021: Board approved Third Amendment to the design contract with Dewberry Engineers, Inc.
5/15/2020: Board adopted an Addendum to the Mitigated Negative Declaration
7/10/2018: Board approved Second Amendment to the design contract with Drake Haglan and Associates, Inc.
5/24/2016: Board approved First Amendment to the design contract with Drake Haglan and Associates, Inc.
11/24/2014: Board adopted a Mitigated Negative Declaration and Mitigation Monitoring Program and approved the Project
9/24/2013: Board approved design contract with Drake Haglan and Associates, Inc.
Fiscal Summary
|
Expenditures |
FY26-27 Adopted |
FY27-28 Projected |
FY28-29 Projected |
|
Budgeted Expenses |
$510,000 |
|
|
|
Additional Appropriation Requested |
|
|
|
|
Total Expenditures |
$510,000 |
|
|
|
Funding Sources |
|
|
|
|
General Fund/WA GF |
|
|
|
|
State/Federal |
$510,000 |
|
|
|
Fees/Other |
|
|
|
|
Use of Fund Balance |
|
|
|
|
General Fund Contingencies |
|
|
|
|
Total Sources |
$510,000 |
|
|
Narrative Explanation of Fiscal Impacts:
Appropriations for the proposed contract change order are available in the FY 26-27 Roads Capital (11051- 34010103) budget. The project is eligible for 88.7% reimbursement through the Federal Highways Administration (FHWA). SPI has applied for reimbursements of these expenditures, but the application has not been approved yet. In the event the application is denied, the Department would use annual allocations from traditional Road funding sources such as Highway User Tax Account (HUTA) or Road Maintenance and Rehabilitation Account (SB1) to pay for the additional contract costs.
Narrative Explanation of Staffing Impacts (If Required):
None.
Attachments:
None.
Related Items “On File” with the Clerk of the Board:
None.