To: Board of Supervisors
Department or Agency Name(s): Sonoma County Public Infrastructure
Staff Name and Phone Number: Johannes J. Hoevertsz, 707-565-2550
Vote Requirement: Majority
Supervisorial District(s): Countywide
Title:
Title
Gas Collection and Control System and Leachate Collection and Recovery System Maintenance
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Recommended Action:
Recommended action
Authorize the Director of Public Infrastructure to execute an agreement with Tetra Tech BAS, Inc., for a term of up to five years through January 5, 2029, and a not to exceed amount of $122,407 per year for labor, equipment, and materials for the ongoing maintenance of landfill gas and leachate extraction systems located the Healdsburg closed landfill; and a not to exceed amount of $75,000 per task order for Non-Routine Services for the maintenance of leachate control and removal systems for the Annapolis, Guerneville, Occidental, Airport, Roblar, and Sonoma closed landfill sites.
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Executive Summary:
The County is responsible for maintaining seven (7) closed landfill sites in the County. The landfills were closed during the 1980s and 1990s and are in a post-closure maintenance period. Though they are no longer receiving waste, they still can pose a potential risk to air and water quality along with human health and safety if not maintained properly. For this reason, the sites must be maintained and monitored within the regulatory framework of state and local regulations, in perpetuity, or until such time that the reporting indicates that the sites no longer pose a risk to the environment. The Department of Public Infrastructure (SPI), Integrated Waste Division, is recommending to enter into an agreement with Tetra Tech BAS, Inc. to provide such services in order to comply with State and Local regulations, for a term of up to five years, and a not to exceed annual amount of $122,407 for Routine Services and a not to exceed amount of $75,000 per task order for Non-Routine Services through January 5, 2029.
Discussion:
Background
The Healdsburg Landfill was operated as a Class III sanitary landfill until August of 1989 when the adjacent transfer station began operations. Before 1989 it was operated as a modified canyon fill from 1971 to 1989 and prior to 1971, a five-acre portion of the site had been operated as an open burn dump.
Prior to closure, the landfill had accepted up to a permitted maximum of 220 tons per day of non-hazardous and inert wastes primarily from residential and commercial sources for disposal. The landfill currently has an in-place volume of approximately 1.5 million cubic yards of solid waste.
The site was closed in conformance with Title 14 and Title 23 (currently Title 27) of the California Code of Regulations (CCR) in 1989.
Maintenance Overview of the Healdsburg Facility
The Landfill Gas Collection and Control System (LFGCCS), includes a landfill gas flare, which can burn 400 cubic feet per minute of Landfill Gas (LFG) extracted from gas extraction wells. The system was installed in 2000, in part, to reduce the possibility of LFG migration outside of the landfill footprint and to prevent LFG migration up through the landfill surface and into the atmosphere. The purpose of the LFGCCS is to maintain subsurface concentrations of LFG below 5% methane by volume at the LFG perimeter probe network pursuant to CCR Title 27 regulations.
The majority of the extraction wells at the Healdsburg Landfill extract LFG only, while others were constructed as dual-purpose wells, extracting both LFG and water that has percolated through the landfill waste, also known as leachate.
Due to the specialized nature of closed landfills and the unique qualifications, equipment, and materials required to maintain such systems, the County has for multiple decades contracted for the services to firms that are better positioned to provide the specialized and independent services for the maintenance, monitoring, and reporting requirements for the County’s closed landfills.
For purposes of this contract, “Routine Services” (Tasks 1-4) include the regularly scheduled operation, maintenance, monitoring, testing, and reporting activities required to keep the landfill gas and leachate control systems in regulatory compliance. “Non-Routine Services” (Task 5) include corrective maintenance, repairs, replacements, troubleshooting, emergency response work, and other unscheduled activities outside of normal O&M. Non-Routine Services are performed only through separate, County-approved Task Orders.
Selection Process
An RFP for the LFGCCS and LCRS maintenance work was posted to the County’s Portal on September 11, 2025. As a result of the posting the County received four (4) proposals from the following firms:
1. Aptim Environmental Infrastructure LLC.
2. Blue Flame Crew West LLC
3. Tetra Tech BAS, Inc.
4. SCS Engineers
A three-person panel was assigned to review the proposals. Two of the members of the panel were from SPI, Integrated Waste Division, and one member was from Sonoma County Environmental Health, Local Enforcement Agency. The panel ranked proposals based on technical merits of the proposals and ability to perform the work as opposed to costs. After reviewing the proposals, Tetra Tech BAS was ranked highest and was determined to best serve the County’s needs.
Recommendation
Based on the results of the RFP, SPI is recommending approval and authorization for the Chair to sign the Agreement for Professional Services with Tetra Tech BAS, Inc. to provide landfill gas collection and control systems maintenance, monitoring, and reporting services at the Healdsburg Closed Landfill and leachate collection and recovery system services at the Annapolis, Guerneville, Healdsburg, Roblar, and Sonoma closed landfills, for a term of three years with two (2) optional one (1) year extensions, and a not to exceed annual amount of $122,407 for Routine Services and a not to exceed amount of $75,000 per task order for Non-Routine Services, through January 5, 2029.
Strategic Plan:
N/A
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
01/05/2021: Board approved the Agreement with Tetra Tech BAS, Inc. for Landfill Gas Collection Services for the Healdsburg Closed Landfill.
09/22/2020: Board approved Amendment No. 3 to the Agreement with SCS Field Services
04/07/2020: Board approved Amendment No. 2 to the Agreement with SCS Field Services
11/13/2018: Board approved Amendment No. 1 to the Agreement with SCS Field Services
04/01/2015: Board approved the Agreement with SCS Field Services for Landfill Gas Collection Services for the Healdsburg Closed Landfill.
Fiscal Summary
|
Expenditures |
FY25-26 Adopted |
FY26-27 Projected |
FY27-28 Projected |
|
Budgeted Expenses |
$197,407 |
$197,407 |
$197,407 |
|
Additional Appropriation Requested |
|
|
|
|
Total Expenditures |
$197,407 |
$197,407 |
$197,407 |
|
Funding Sources |
|
|
|
|
General Fund/WA GF |
|
|
|
|
State/Federal |
|
|
|
|
Fees/Other |
$197,407 |
$197,407 |
$197,407 |
|
Use of Fund Balance |
|
|
|
|
General Fund Contingencies |
|
|
|
|
Total Sources |
$197,407 |
$197,407 |
$197,407 |
Narrative Explanation of Fiscal Impacts:
The proposed Agreement outlines payments not to exceed $122,407 per year for Routine Services and a not to exceed amount of $75,000 per task order, for up to three years, with an option of two (2) 1-year extensions. Appropriations of $122,407 for routine and $75,000 for non-routine work are included in the FY 2025-26 adopted Former Urban Landfill budget. SPI projects that annual costs for non-routine repair services will not exceed $75,000. If repair requirements exceed this projection, staff may request additional budget appropriations.
Funding for maintenance at the Healdsburg, Sonoma and Roblar Landfills is stipulated by the Landfill Settlement Agreement (LSA) between the County of Sonoma and the Committed Cities, which became effective on April 1, 2015. The LSA directs the collection of Concession Fees for each ton of Municipal Solid Waste and Organic Waste (Green waste, yard debris, and food waste) received at one of five County-owned Solid Waste Facilities. For the Annapolis and Guerneville Landfills, funding will come from the Rural Landfill Fund.
Narrative Explanation of Staffing Impacts (If Required):
None.
Attachments:
Tetra Tech BAS, Inc. Agreement and Exhibits A-C
Related Items “On File” with the Clerk of the Board:
None.