TO: Board of Supervisors
FROM: Steven Lederer - Director of Public Works Public Works
REPORT BY: German Sierra-Frutos, Engineering Technician
SUBJECT: Approval of Plans and Specifications and Authorization to Advertise for Bids for "Scour Repairs at the Silverado Trail Bridge over Bell Canyon Creek Project”, RDS 20-43 and Approve Amendment No. 2 to Agreement No. 170826B
RECOMMENDATION
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Director of Public Works requests the following actions regarding the “Scour Repairs at the Silverado Trail Bridge over Bell Canyon Creek Project - RDS 20-43:
1. Approval of the plans and specifications and authorization to advertise for sealed bids and opening of the bids at a time, date, and location to be published by the Director of Public Works pursuant to section 20150.8 of the Public Contract Code; and
2. Approval and authorization for the Chair to sign Amendment No. 2 No. 170826B with WRECO to extend the term of the Agreement by two additional fiscal years to provide additional engineering and construction support services for various projects.
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EXECUTIVE SUMMARY
The Bell Canyon Creek Bridge (No. 21C0001) over Silverado Trail is located just north of the intersection of Silverado Trail and Glass Mountain Road. This project will correct potential undermining of an exposed abutment footing which, if not repaired, would put the structure at risk.
WRECO, the design consultant previously hired by the County in support of this project, completed the design, plans, and specifications to replace the existing rock slope protection (RSP) under the bridge with larger RSP. WRECO’s contract expires at the end of the fiscal year, and their services will be needed throughout the project. Thus Staff recommends that the Board approve Amendment No. 2 to WRECO’s contract, the plans and specifications for the project, and authorize the Director of Public Works to advertise for sealed bids for construction.
FISCAL & STRATEGIC PLAN IMPACT
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Is there a Fiscal Impact? |
Yes |
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Is it currently budgeted? |
No |
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Where is it budgeted? |
The existing budget for the Scour Repair at Silverado Trail Bridge over Bell Canyon Creek Project is $212,000 in Fund 2040, Org 2040500 and Project 21031 funded by SB1 SRF. Once construction bids are received, staff will request additional funds from SB 1 for construction, construction management, material testing, contingency, and County staff time. |
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Is it Mandatory or Discretionary? |
Discretionary |
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Discretionary Justification: |
Approval of Amendment No. 2 and approval of the plans and specifications and authorization to advertise for bids is necessary to move the project forward toward construction. Not repairing the scour that has occurred at the bridge foundations could become a public safety issue. |
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Is the general fund affected? |
No |
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Future fiscal impact: |
Staff could request approximately $200,000 in additional SB1 funding to implement the countermeasures portion of the Silverado Trail Bridge over Bell Canyon Creek. It is anticipated that all the work will be completed in fiscal year 2022-23 and the Roads fund will pay for future maintenance work. |
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Consequences if not approved: |
If the Board does not authorize the project to be advertised for sealed bids, construction of the scour countermeasures at the foundation of the bridge could occur in later years, thus putting the safety of travelers on the bridge at risk |
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County Strategic Plan pillar addressed: |
Healthy, Safe, and Welcoming Place to Live, Work, and Visit |
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Additional Information |
On January 26, 2021, the Board appropriated $124,000 for the Scour Plan of Action. On August 24, 2021, the Board approved a budget transfer of $88,000 for the design. |
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: The proposed action is exempt from CEQA, as Per Title 14, California Code of Regulations, Chapter 3, Article 18, Section 15269, Emergency Projects (State CEQA Guidelines) which provides for the maintenance, repair, restoration, demolition, or replacement of property or facilities damaged or destroyed as a result of a disaster stricken area in which a state emergency has been proclaimed by the Governor(15269(a)); and specific actions necessary to prevent or mitigate an emergency(15269(c)) and therefore CEQA is not applicable.
BACKGROUND AND DISCUSSION
The Silverado Trail Bridge over Bell Canyon Creek Bridge (No. 21C0001) is located just north of the intersection of Silverado Trail and Glass Mountain Road, which is approximately 2.5 miles northwest of the City of Saint Helena. In a Bridge Inspection completed on November 25, 2019, Caltrans determined that scour has occurred at the Bell Canyon Creek bridge foundations. However, Caltrans staff could not determine the level of risk associated with the scour. Caltrans requested that the County complete a Scour Plan of Action (SPOA).
A preliminary SPOA was developed by a consultant in the Fall of 2020 and sent to the District Local Assistance Engineer for review and acceptance. Caltrans has accepted the SPOA which required that the County visually monitor the bridge during high water flow events until rock slope protection (RSP) under the bridge can be replaced.
Rock slope protection generally consists of rocks on the channel and structure boundaries to limit the effects of erosion. It is the most common type of scour countermeasure due to its general availability, ease of installation, and relatively low cost. RSP sizing calculations were performed based on the flow characteristics during the 100‐year storm to estimate a minimum recommended rock class to protect the embankment slopes and abutment footings of the existing bridge to mitigate scour and erosion.
Because the history of bridge inspection reports has shown that the observed channel degradation has been regularly reported for several years and appears generally stable, the need for countermeasures installation is not classified as “urgent” or “emergency”. However, because of the potential undermining of the exposed abutment footing and risk to the structure, the installation of the proposed countermeasures is considered of high importance. The County has applied for permits and hopes to get timely approval that will allow the project to start in the beginning of this summer and get completed by the end of summer.
WRECO, the design consultant previously hired by the County to work on this project, completed the plans and specifications to replace the existing rock slope protection (RSP) under the bridge with larger RSP. Their agreement expires at the end of this fiscal year and requires an amendment to extend the term of the agreement because their services will be required during bidding and construction. The current estimated full project cost is $454,000. The project budget is attached for reference and will be further developed. It is recommended that the Board approve the plans and specifications for the project and authorize the Director of Public Works to advertise for the sealed bids for construction.