TO: Board of Supervisors
FROM: Steven Lederer, Director of Public Works
REPORT BY: Estrella Munoz, Junior Engineer
SUBJECT: Approval of Amendment No. 1 to Agreement with ADKO for the "Diamond Mountain Rd Slide Repair", RDS 26-39
RECOMMENDATION
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Approve and authorize the Chair to sign Amendment No. 1 to Agreement No. 260303B with ADKO Engineering, Inc. increasing the contract maximum from $19,507 to $427,692 to provide additional engineering services for Diamond Road Slide Repair Project. (Fiscal Impact: $400,000 Expense, additional funds requested for the project costs; General Fund; Reallocation of Budget; Discretionary)
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BACKGROUND
Damage occurred at 1699 Diamond Mtn Rd during the storm events that started in November 2025. The failure at Diamond Mountain Rd consists of an upslope failure on the east side of the roadway that extends approximately 230 linear feet in length. Slide debris filled and blocked the creek channel adjacent to the roadway causing water to be pushed out of the creek channel and across the roadway. Because construction will take place adjacent to or within the channel, environmental regulatory agency permits will be required.
On March 10, 2026, the Board of Supervisors authorized creation of the "Diamond Mountain Rd Slide Repair" project and a budget transfer of $100,000 was allocated for the project using the Roads Operating Fund. Of this amount, $90,000 was allocated for consultant services and $10,000 for staff time. Following the budget transfer and approval of the agreement with ADKO, the County moved forward with a feasibility study that explored three potential repair methods. The feasibility study involved estimation of repair costs and evaluation of potential environmental impacts and mitigation related to each of the following repair methods:
1. 10-foot tall retaining wall adjacent to roadway - Engineer's Estimate: $866,000
This repair method would protect the edge of the roadway but would not prevent continued deb...
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