To: Board of Directors, Sonoma Valley County Sanitation District
Department or Agency Name(s): Sonoma Valley County Sanitation District
Staff Name and Phone Number: Greg Guensch 707-547-1972
Vote Requirement: Majority
Supervisorial District(s): First
Title:
Title
Environmental Resource Consulting and Engineering Design Services for Sonoma and Kohler Creeks Bank Repair Project
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Recommended Action:
Recommended action
Authorize Sonoma County Water Agency’s General Manager acting on behalf of Sonoma Valley County Sanitation District to execute the Fourth Amended and Restated Agreement for Engineering and Design Services for Sonoma and Kohler Creeks Bank Repair Project with Prunuske Chatham, Inc., in a form approved by County Counsel. The amended agreement increases the amount by $45,080 and extends the agreement term by two years for a new not-to-exceed agreement total of $393,980 and end date of December 31, 2025. (First District)
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Executive Summary:
In an ongoing effort to maintain the sanitary sewer collection system in Sonoma Valley, avoid unnecessary damage or failures and repair costs, and protect the environment, the Sonoma Valley County Sanitation District (District) is proposing to expand the design and bank stabilization work under the existing agreement to perform creek bank stabilization work at 13975 Arnold Drive, Glen Ellen, California (Project). The purpose of the Project is to stabilize two areas of eroding bank on Sonoma Creek and one area of erosion on Kohler Creek that pose risks to the sanitary sewer trunk main, two manholes, and a siphon under Sonoma Creek that are owned by the District. Due to recent observations of the exposed siphon pipe in the bottom of Sonoma Creek, and discussions with the property owner, the extent of bank stabilization has been expanded and an additional Project element has been added to protect the exposed siphon pipe. This amended agreement adds tasks and funds for the expanded bank stabilization area and the siphon pipe protection to the current agreement.
Discussion:
HISTORY OF ITEM/BACKGROUND
The District operates the sanitary sewer collection system in Sonoma Valley. A portion of the sewer pipeline system, in the Glen Ellen area, runs parallel to Sonoma Creek and crosses Kohler and Sonoma creeks near the confluence of these two channels. The District is currently working with Prunuske Chatham, Inc. (Consultant) on the engineering design to repair two sites on the bank of Sonoma Creek and one site on Kohler Creek in order to protect the District’s sanitary sewer infrastructure that is exposed and at risk of damage and possible failure during high-intensity stream flows (including the trunk main, two manholes, and a siphon under Sonoma Creek that could result in a wastewater spill into Sonoma Creek). The sites are located on private property along the back yard of 13975 Arnold Drive in Glen Ellen.
Severe erosion occurred during the unusually wet 2016-2017 winter, and subsequent high flows that resulted from a storm event on February 26, 2019, exposed some of the at-risk infrastructure. Temporary emergency measures were installed in April 2019 to stop the erosion and protect infrastructure from damage. These measures were constructed under a temporary emergency permit using Federal Emergency Management Agency (FEMA) public assistance grant funding, however, and it was not possible to design and implement measures that met all the permitting and California Environmental Quality Act (CEQA) requirements. As such, the District must remove or modify the temporary measures and replace them with permanent measures that have been properly permitted and satisfy CEQA requirements.
These sites are identified as vulnerabilities in the District's FEMA-approved 2016 Local Hazard Mitigation Plan. Specific hazards listed include static and seismic embankment failure potential, and potential exposure and damage of the pipeline due to erosion and debris impact during periods of rapid creek flow.
Sonoma Creek at this location also provides habitat for threatened and endangered species and it is important to avoid impacts to this sensitive area. The sensitive nature of the site and the severity of the bank erosion warrants the services of a specialist in bio- and geo-technical stream bank repair in sensitive settings.
The District and Consultant entered into an agreement for environmental resource consulting, alternative assessment and preliminary initial engineering design of the creek bank stabilizations measures, dated December 19, 2018, in the amount of $50,000. The consultant developed 30% design documents and identified environmental compliance requirements under this agreement.
The first amended agreement, approved by the General Manager of Sonoma County Water Agency (Sonoma Water) on behalf of the District on April 10, 2019, expanded the scope to add an optional task to perform additional services as requested by Sonoma Water to support the project at no additional cost to the District or extension of term.
The second amended agreement, approved by Sonoma Water’s General Manager on behalf of the District on November 17, 2020, extended the agreement by six months to June 30, 2021, to continue work at no additional cost to the District or expansion of scope.
The third amended agreement, approved by the Board on April 13, 2021, expanded the scope of work to include engineering design to 100 percent, completion of environmental documentation, and assistance during bidding and construction; increased the agreement amount by $298,900 for a new not-to-exceed total of $348,900; and extended the agreement by 18 months to December 31, 2023. The term of the agreement was extended to provide the time required to advance the designs from 30% to 100 percent/final, obtain permits and CEQA approval, and for Sonoma Water to secure the property rights necessary to construct and maintain the project. The project was also delayed due to the staffing and scheduling impacts related to shelter-in-place orders and other disruptions associated with Covid-19 pandemic, which affected the District, the Consultant, and the Resource Agencies.
SELECTION PROCESS
Consultant was selected from a list of qualified consultants developed from a competitive selection process. Attachment 1 provides a summary of the competitive selection process.
Consultant was selected for the subject work because of its experience with riparian and wetland restoration design, fluvial geomorphology, creek bank stabilization, and construction in sensitive creek environments.
SERVICES TO BE PERFORMED
Under the proposed amended agreement, Consultant will provide additional engineering services for the additional bank repair design, including revising the completed CEQA studies and project description to encompass the slightly larger footprint of the expanded Project.
This amended agreement is necessary because the Project footprint has been expanded and an additional Project element has been added to protect a siphon pipe that is now exposed on the bottom of Sonoma Creek.
The additional cost is $45,080, for a new not-to-exceed agreement total of $393,980. The new end date is December 31, 2025.
Strategic Plan:
N/A
Sonoma Water Strategic Plan Alignment
Waste Water Treatment and Water Reuse, Goal 1: Improve operational reliability of wastewater treatment and water reuse systems.
This Project will increase the operational reliability of the District’s sanitary sewer collection system by preventing bank erosion and bed incision in Sonoma and Kohler Creeks from rupturing at-risk sanitary sewer pipes and manholes. Damage to the pipes being protected by this Project could cause a release of raw sewage into Sonoma Creek, creating a water quality impact, or allowing water from Sonoma or Kohler Creeks to flood into the sanitary sewer system.
Prior Board Actions:
4/13/2021: Approved third amended agreement between the District and Prunuske Chatham, Inc. for environmental consulting and engineering design services. Cost $348,900; term end December 31, 2023.
12/11/2018: Approved agreement between the District and Prunuske Chatham, Inc. for environmental resource consulting and engineering design services. Cost $50,000; term end December 31, 2020.
Fiscal Summary
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Expenditures |
FY 22-23 Adopted |
FY23-24 Projected |
FY 24-25 Projected |
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Budgeted Expenses |
$45,080 |
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Additional Appropriation Requested |
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Total Expenditures |
$45,080 |
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Funding Sources |
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General Fund/WA GF |
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State/Federal |
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Fees/Other |
$45,080 |
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Use of Fund Balance |
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Contingencies |
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Total Sources |
$45,080 |
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Narrative Explanation of Fiscal Impacts:
Budgeted amount of $45,080 is available from FY 2022/2023 appropriations for the Sonoma Valley County Sanitation District Operations Fund. No additional appropriation is required.
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Staffing Impacts: |
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Position Title (Payroll Classification) |
Monthly Salary Range (A-I Step) |
Additions (Number) |
Deletions (Number) |
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Narrative Explanation of Staffing Impacts (If Required):
N/A
Attachments:
Attachment 1: Selection Memo
Related Items “On File” with the Clerk of the Board:
None