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File #: 2022-0436   
Type: Consent Calendar Item Status: Agenda Ready
File created: 4/6/2022 In control: Transportation and Public Works
On agenda: 5/24/2022 Final action:
Title: Professional Services Agreement with TRC Engineers, Inc. for design of the Asti Permanent Bridge Crossing Project (C21901).
Department or Agency Name(s): Transportation and Public Works
Attachments: 1. Summary Report, 2. Agreement

To: Board of Supervisors

Department or Agency Name(s): Transportation and Public Works

Staff Name and Phone Number: Johannes J. Hoevertsz, 707-565-2231

Vote Requirement: Majority

Supervisorial District(s): Fourth




Professional Services Agreement with TRC Engineers, Inc. for design of the Asti Permanent Bridge Crossing Project (C21901).



Recommended Action:

Recommended action

Award and authorize the Chair to execute a professional services agreement with TRC Engineers, Inc. for design, engineering, and environmental services associated with a permanent bridge over the Russian River in Asti for a total not-to-exceed value of $3,986,231 ($3,623,847 base plus 10% contingency of $362,385), for a term of seven years. (Fourth District)



Executive Summary:

The Department of Transportation and Public Works (TPW) is requesting approval of a Professional Services Agreement (PSA) with TRC Engineers, Inc. for design, engineering and environmental services associated with the construction of a permanent bridge over the Russian River in Asti. The proposed contract has a seven-year term with a total, not-to-exceed value of $3,986,231 ($3,623,847 base plus 10% contingency of $362,385).

If constructed, the project would replace a seasonal bridge which is installed and removed each year by TPW Road Maintenance crews over the Russian River at Washington School Road in Asti.  A permanent bridge would meet all current design and safety standards. A permanent bridge would provide many benefits, including the following:

1.                     Reduce the long-term cost to the County of providing a Russian River crossing in Asti.

2.                     Provide permanent ingress and egress for residents and first responders to the east side of the Russian River in northern Sonoma County in the event of a natural disaster or other emergency.

3.                     Eliminate the environmental impact of installing and removing a seasonal crossing each year.  

Based on projected design, right of way, and construction costs TPW currently estimates the cost of the proposed project at $30,000,000. With the assistance of County Counsel, Auditor, Controller, Treasurer, Tax Collector staff, outside bond counsel, and KNN Public Finance, TPW is exploring financing options, including formation of a special assessment district through which property owners receiving a special benefit would fund a portion of the project. The balance of the project would be financed through funding sources approved the County Debt Advisory Committee and this Board.



Each year, for approximately 100 years, County Road Maintenance crews install and remove a seasonal bridge over the Russian River at Washington School Road in Asti. Depending on weather conditions and water-flow in the Russian River, the temporary crossing is normally installed prior to Memorial Day weekend and removed in late October. In addition to offering more convenient access to the east side of the Russian River for local residents, the crossing offers the additional benefit of a secondary evacuation route as demonstrated during both the 2017 Sonoma County Complex Fires, and the 2019 Kincade Fire.

Annual installation/removal costs for the Asti crossing have historically averaged $160,000 but increased to over $450,000 following the flood event of 2019, which realigned the river’s low flow channel towards the center of the embankments. Based on current site conditions, TPW estimates that the ongoing annual cost for installing and removing the temporary crossing including permitting will exceed $250,000 per year, at minimum, and could increase if future changes in the channel necessitate another temporary bridge.  In addition to rising annual costs, there are also vehicle limitations and significant environmental impacts and permitting associated with the current seasonal crossing.   There is a 13-ton weight limitation on vehicles using the temporary one lane bridge crossing. There are also significant environmental impacts resulting from the temporary road approaches being constructed by pushing gravel into the river from the banks towards the temporary bridge crossing.

In response to the costs, environmental impacts, and physical limitations associated with a seasonal crossing, TPW has worked with property owners in the Asti/Cloverdale area to initiate formation of a Special Assessment District to identify a funding source for a permanent structure.  A feasibility study has been completed, and on July 13, 2021, this Board approved moving forward with formation of an assessment district and preparation of an Engineer’s Report for the construction of a permanent bridge. District formation proceedings will be brought to the Board at a later date. 

TPW issued a Request for Proposals for design, engineering and environmental services on February 8, 2022.  Written proposals from TRC Engineers Inc., Biggs Cardosa Associates Inc., and Corner Stone Structural Engineering Group, Inc. on March 4, 2022. Proposals were evaluated by the County’s Evaluation Committee, which was followed by oral interviews with TRC Engineers and Biggs Cardosa Associates Inc. TRC Engineers, Inc. was the highest-ranked proposer.  

To support the funding structure, while achieving the project goals, the proposed contract has been split into three phases:

                     Phase 1: Preparation of preliminary engineering plans & and environmental constraints memorandum.

                     Phase 2: Preparation of final plan, specification & engineer’s estimate (PS&E) including all civil, structural, environmental, geotechnical, right-of-way and other services necessary to complete the PS&E and obtain all permits, clearances and agreements necessary to build the new bridge.

                     Phase 3: Construction support. The consultant will also be retained to provide bid support, design support during construction, and project closeout tasks.

Phase 1 is intended to be completed within 12 months of project initiation and will cost approximately $350,000.  Phase 1 is the only work guaranteed in the proposed contract. The remaining work is contingent on the Board’s approval of a financing plan for the project.

TPW recommends approval of the agreement with TRC Engineers, Inc. for a seven-year term and a total not-to-exceed amount of $3,986,231, which includes a 10% contingency.


Strategic Plan:

This item directly support 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 4: Identify and retrofit bridges in County that are at high risk for damage during earthquakes.


Prior Board Actions:

7-13-2021:  Initiation of Proceedings to Form an Assessment District to Fund a Portion of the Cost of a Permanent Bridge at the Washington School Road Crossing of the Russian River Near the Community of Asti.

12-10-2019:  Authorization to work with community groups on long term options for the seasonal crossings and funding a feasibility study for the assessment district.


Fiscal Summary


FY 21-22 Adopted

FY22-23 Projected

FY 23-24 Projected

Budgeted Expenses




Additional Appropriation Requested




Total Expenditures




Funding Sources




General Fund/WA GF












Use of Fund Balance








Total Sources





Narrative Explanation of Fiscal Impacts:

Expenses for Phase I of this contract are included in the FY 2022-23 Roads Capital (11051-34010103) recommended budget. Pending Board approval of a bridge financing plan, the remaining design and construction expenditures for this project will be included in future Roads Capital recommended budgets. The source of funds for FY 2022-23 expenditures is a one-time, $250,000 allocation from District 4 PG&E Tier 2 funds and traditional Roads funding sources including allocations from HUTA and SB1. Funding for future phases is yet-to-be determined, but will be brought to this Board for approval at a future date. If a bridge financing plan is not approved, the contract can be terminated per section 4.1 of the attached PSA.


Narrative Explanation of Staffing Impacts (If Required):






Related Items “On File” with the Clerk of the Board: