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: 4/5th
Supervisorial District(s): First, Second, Fourth, Fifth
Title:
Title
Third Amendment - Engineering Services for Design of Leachate and Potable Water Storage Tank Replacements Project
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Recommended Action:
Recommended action
Authorize the Chair to execute a Third Amendment to the Professional Agreements with GHD, Inc. for design services for the leachate tank at the Roblar location to increase the total contract amount by $28,835.81, for a new, total, not-to-exceed amount of $836,969.81.
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Executive Summary:
Sonoma County Public Infrastructure is requesting authorization to execute a Third Amendment to an agreement with GHD, Inc. expanding the scope of work, and increasing the total, not-to-exceed contract amount to $836,969.81. The Third Amendment does not change the term of the contract, however, it incorporates an expanded scope of work (Task 10), associated with project design modifications due to unforeseen field conditions discovered during construction at the Roblar Site related to drainage, slope stability, and erosion control measures. The agreed upon amount for work associated with Task 10/Third Amendment is $28,835.81.
Discussion:
Background:
On July 20, 2021, the board approved a Professional Services Agreement with GHD, Inc for the design of a leachate and potable water storage tanks for a not to exceed contract value of $651,775.30. The Agreement provided geotechnical investigation, design plans and drawings, bidding and construction support services, and other related engineering services to replace existing leachate storage facilities at the Guerneville, Roblar, and Sonoma Closed Landfills and certain potable water tanks at the Madrone Avenue, Hilltop Road, and Del Rio sites that make up the Fitch Mountain Water System (FMWS). The term of the executed Agreement was three years with two (2) one-year extension options.
On May 24, 2022, the Board approved the First Amendment to the Agreement which increased the contract by $78,193 for a new, total, not to exceed amount of $729,969. The work associated with the increased cost in the First Amendment included expanded geotechnical investigations for recommended water tank locations, design of a retaining wall for leachate tanks at the Roblar landfill site, and design costs for adding fill stations at Guerneville and Sonoma landfill sites. There was no change in term associated with the First Amendment.
On July 8, 2025, the Board approved a Second Amendment to the Agreement increasing the contract by $78,164, for a new, total, not to exceed amount of $808,134. The Second Amendment and associated cost increase was the result of the initial construction bid not being awarded, requiring the project to be re-bid. This triggered the need for revised cost estimates, updated technical specifications, and additional bid-phase support from GHD. These updates were necessary to reflect changes in material pricing, including tariff-related fluctuations that impacted the cost of steel and other supplies since the original design work was completed.
In December 2024, unanticipated site conditions related to site drainage were discovered during construction at the Roblar location. Construction work was suspended, while design modifications were assessed and the following changes and modifications were incorporated into the project:
• New underground drainage pipes
• Regrading of the site
• New AC pavement across the site
• Additional guardrail
• New retaining wall
• Improved slope stability and erosion control measures
The need to stop work at this location caused this site to become the critical path for the construction timeline. The redesign by GHD was performed immediately in efforts to resolve this time-sensitive issue. Though a Second Amendment was approved in July 2025, this additional work was not included and necessitated a Third Amendment at a later date. The proposed amendment will allow SPI to pay for work already performed by GHD, and staff recommends that the Board authorize the Chair to execute the Third Amendment to the Professional Services Agreement with GHD, Inc., increasing the contract by $28,835.81, for a new total not-to-exceed amount of $836,969.81.
Strategic Plan:
N/A
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
07/28/2025 Board approved the Second Amendment to the Agreement for Engineering Services for Design of Leachate and Potable Water Storage Tanks Replacement Project with GHD, Inc.
05/24/2022 Board approved the First Amendment to the Agreement for Engineering Services for Design of Leachate and Potable Water Storage Tanks Replacement Project with GHD, Inc.
07/20/2021 Board approved the Agreement for Engineering Services for Design of Leachate and Potable Water Storage Tanks Replacement Project with GHD, Inc.
Fiscal Summary
|
Expenditures |
FY26-27 Adopted |
FY27-28 Projected |
FY28-29 Projected |
|
Budgeted Expenses |
$28,835.81 |
|
|
|
Additional Appropriation Requested |
|
|
|
|
Total Expenditures |
$28,835.81 |
|
|
|
Funding Sources |
|
|
|
|
General Fund/WA GF |
|
|
|
|
State/Federal |
|
|
|
|
Fees/Other |
$28,835.81 |
|
|
|
Use of Fund Balance |
|
|
|
|
General Fund Contingencies |
|
|
|
|
Total Sources |
$28,835.81 |
|
|
Narrative Explanation of Fiscal Impacts:
Cost associated with the additional work to be completed with the Third amendment are estimated to be $28,835.81. If approved, The FY 2026-27 Former Urban Landfill Adopted Budget (41123-34050300) includes sufficient appropriations to support additional costs.
Funding sources for maintaining the county closed landfills include collection of Franchise Fees under two Franchise Agreements and the collection of Concession Fees collected under a Master Operations Agreement with Republic Services of Sonoma County, Inc.
Narrative Explanation of Staffing Impacts (If Required):
None.
Attachments:
Third Amendment
Exhibit A Scope of Services
Exhibit B Cost of Services
Exhibit C Schedule of Rates
Related Items “On File” with the Clerk of the Board:
None.