Title
Environmental Management Department recommending the Board consider the following pertaining to the Union Mine Wastewater Treatment Plant Cleaning of Digester 1:
1) Approve and adopt the specifications and authorize the Chair to sign the bid documents contingent on County Counsel and Risk Management approval; and
2) Authorize the advertisement for contractor bids (BID Number 2025-0163) in the Quest Construction Data Network.
FUNDING: Non-General Fund / CSA 10 Liquid Waste Funds.
Body
DISCUSSION / BACKGROUND
El Dorado County owns, operates, maintains, and monitors the Union Mine Wastewater Treatment Facility, located at 5700 Union Mine Road, El Dorado, CA 95623. The facility, which began operations in 1996, receives leachate from the on-site landfill, as well as residential septic tank waste and portable toilet waste generated on the West Slope of the County.
During recent operations, County staff discovered that the centrifuge feed line had become severely compacted with grit and sludge. This blockage resulted in equipment failure and a full system shutdown. Despite multiple attempts to clear the line, the issue remains unresolved, necessitating immediate cleaning of the aerobic digester.
As a result of the system shutdown, the Union Mine Wastewater Treatment Plant will be closed to liquid waste haulers beginning December 13, 2025, and will remain closed until repairs are completed.
To address this urgent need, the County is issuing a Request for Proposals (RFP) to qualified contractors. The scope of work includes:
1. Removal and dewatering of all material from the open-top, 500,000-gallon aerobic digester.
2. Inspection and performance of all necessary maintenance on digester components, including the aeration system, sludge feed line, and floating decanter, as determined by the County.
This work is critical to restoring operations at the facility and minimizing service disruptions to County residents and liquid waste haulers.
ALTERNATIVES
The Board may choose to deny approval of this construction project. If that occurs, the Union Mine Wastewater Treatment Plant will remain closed until Digester #1 is cleaned and repaired. As a result, liquid waste haulers serving County residents would need to transport waste to alternative facilities outside the County. This burden would likely lead to increased service costs for septic tank pumping and related services.
PRIOR BOARD ACTION
N/A
CAO RECOMMENDATION/COMMENTS
Approve as recommended.
FINANCIAL IMPACT
There is no change to Net County Costs associated with this item. The Fiscal Year 2025-26 recommended budget includes sufficient funding for this project.
CLERK OF THE BOARD FOLLOW UP ACTIONS
N/A
STRATEGIC PLAN COMPONENT
Public Infrastructure
CONTACT
Jeffrey Warren, REHS
Director of Environmental Management