TO: Board of Supervisors
FROM: Steve Lederer, Director of Public Works
REPORT BY: Liang Chin Su, Assistant Engineer
SUBJECT: Award of Construction Contract and Approval of Amendment No. 1 to Agreement No. 260302B for the “550 Wall Road Landslide Repairs Project”, RDS 26-38.
RECOMMENDATION
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Award of Construction Contract to North Bay Excavation, Inc. of Valley Ford, California in the amount of $567,058 for the “550 Wall Road Landslide Repairs Project”, RDS 26-38 (Project 26028); and approve and authorize Amendment No. 1 to Agreement No. 260302B with ADKO Engineering, Inc. increasing the contract maximum from $319,389 to $356,740 to provide additional engineering services for the Project. (Fiscal Impact: $900,000 Expense for the construction contract and other project costs; General Fund, Reallocation of Budget; Discretionary)
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BACKGROUND
Two slides occurred on Wall Road in November of 2025: one adjacent to the slide at 555 Wall Road that developed during the 2019 storms, and a second approximately 500 feet north of the first. The 2019 Wall Road slide remains mired in the FEMA review process and will move forward to construction once the necessary approvals are received. Both 2025 slide locations exhibit roadway and embankment failure along the north side of the roadway, where portions of the pavement and supporting slope have moved downslope, compromising the stability of the remaining roadway. The slide areas are approximately 70 linear feet and 30 linear feet in length, respectively. The designed repairs for both locations are the construction of reinforced concrete retaining walls, approximately four to six feet in height, supported by cast-in-drilled-hole piles. In addition, approximately 100 feet of roadway, 42 feet in width, will be reconstructed and paved at each slide location to restore roadway integrity and pavement conditions.
On March 10, 2026, the Board of Supervisors authorized creation of the “550 Wall Road Landslide Repairs Project”, RDS 26-38 (project 26028) and a budget transfer of $399,389 was allocated for the project using the Roads Fund (Fund 2040, Sub-Division 2040000). Of this amount, $319,389 was allocated for design services and $80,000 for staff time.
On June 16, 2026 the Board of Supervisors approved the plans and specifications and authorized to advertise for sealed bids and opening of the bids pursuant to Section 20150.8 of the Public Contract Code. On July 14, 2026, bid were received and opened. The bid results are presented below:
|
Vendor |
Bid |
|
North Bay Excavation, Inc. |
$567,057.60 |
|
Rehak General Engineering, LLC. |
$582,232.00 |
|
Rege Construction, Inc. |
$650,476.00 |
|
Amer Construction, Inc. |
$655,391.19 |
|
Maggiora & Ghilotti, Inc. |
$671,176.00 |
|
Wright Construction Engineering Corp. |
$685,183.50 |
|
W.R. Forde Associates, Inc. |
$712,772.00 |
|
Granite Rock Company |
$713,269.00 |
|
Granite Construction Company |
$865,200.56 |
Staff recommends awarding the contract to the lowest responsive bidder, North Bay Excavation, Inc. of Valley Ford, CA for their base bid of $567,057.60. North Bay Excavation’s bid was lower than the engineer’s estimate of $667,000. The total project cost, including design and engineering, construction, construction management, and contingency is $1,299,389. The cost breakdown includes $567,058 for construction, $113,412 for 20% construction contingency, $37,351 for additional biological and cultural monitoring services, $120,000 for construction management, $62,179 for geotechnical observation and material testing, and $399,389 for design and staff time.
Included in the Fiscal Year 2026-27 budget is $7 million in Project RDS01 for a list of 2025 November Storm projects with not-to-exceed project amounts approved by the Board. Wall Road (2 Locations) Landslide Repairs Project (26028) was on the list with a not-to-exceed amount of $1,000,000 (excluding the $399,389 that was previously allocated for design and staff time). With respect to this agenda item, a budget amendment and subsequent transfer of funds will be prepared to reallocate $900,000 from RDS01 to Project 26028. These actions will be reviewed and approved by the County Executive Office and the Auditor-Controller Office to ensure compliance with the adopted budget and availability of funds.
In addition, staff recommends approval and authorization of Amendment No. 1 to Agreement No. 260302B with ADKO Engineering, Inc. to provide biological and cultural monitoring services during construction. The monitoring work will provide implementation of avoidance and minimization measures to prevent regulatory violations with the California Department of Fish and Wildlife (CDFW) if protected species are discovered near project locations during construction.
Requested Actions:
1. Award of the Construction Contract for the “550 Wall Road Landslide Repairs Project”, RDS 26-38 to North Bay Excavation, Inc. of Valley Ford, California for their low base bid of $567,057.60 and authorization for the Chair to sign the construction contract; and
2. Approve and authorize Amendment No. 1 to Agreement No. 260302B with ADKO Engineering, Inc., for an additional $37,351, and therefore, for a new maximum contract amount of $356,740 to provide additional engineering services for the “550 Wall Road Landslide Repairs Project”, RDS 26-38.
FISCAL IMPACT
|
Is there a Fiscal Impact? |
Yes |
|
Is it currently budgeted? |
Yes |
|
Where is it budgeted? |
Roads Fund, Division 20405 |
|
Is it Mandatory or Discretionary? |
Discretionary |
|
Discretionary Justification: |
Approval is needed to bring the project to construction |
|
Is the general fund affected? |
Yes |
|
Future fiscal impact: |
Construction will finish in FY 26-27 with no future impacts beyond standard roadway maintenance |
|
Consequences if not approved: |
The landslides occurred near 550 Wall Road will not be repaired, creating a roadway safety hazard for residents living on Wall Road |
|
Strategic Pillar |
Build healthy, connected communities |
ENVIRONMENTAL IMPACT
ENVIRONMENTAL DETERMINATION: Categorical Exemption Section 15301 Class 1 - Existing Facilities and Section 15302 Class 2 - Replacement or Reconstruction: It has been determined that this type of project does not have a significant effect on the environment and is exempt from the California Environmental Quality Act. [See Class 1 (“Existing Facilities”) and Class 2 (“Replacement or Reconstruction”) which may be found in the guidelines for the implementation of the California Environmental Quality Act of 14 CCR §15301; see also Napa County’s Local Procedures for Implementing the California Environmental Quality Act Appendix B.]