To: Sonoma County Board of Supervisors
Department or Agency Name(s): Permit and Resource Management Department
Staff Name and Phone Number: Reg Cullen, 707-565-2502
Vote Requirement: 4/5th
Supervisorial District(s): Fifth
Title:
Title
Roiling Permit and Permit Extensions under Ordinance No.3836R to City of Santa Rosa, Delta Pond Diffuser Maintenance on Santa Rosa Creek; ROI22-0002
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Recommended Action:
Recommended action
To adopt a resolution making responsible agency findings under the California Environmental Quality Act (CEQA) and issuing a roiling permit (Ordinance No. 3836R) and necessary permit extensions to the City of Santa Rosa for pond diffuser maintenance in Santa Rosa Creek for property located at 4350 Guerneville Rd., Santa Rosa; APN 130-040-014 (Fifth District)(4/5th Vote Required).
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Executive Summary:
Sonoma County requires that an application for a permit, known as a roiling permit, be filed with the Board of Supervisors prior to work or operations in a river, stream, or channel which may decrease the clarity of these waterways. The recommended resolution will issue a roiling permit to the City of Santa Rosa for pond maintenance at Santa Rosa Creek beginning on September 1, 2022. Permit and permit extensions for work within a channel or stream must be approved by the Board of Supervisors. On January 20, 2022, the City of Santa Rosa as CEQA lead agency adopted a Mitigated Negative Declaration (MND) for the Delta Pond Discharge Diffuser Maintenance Project at the City’s Laguna Treatment Plant. The requested roiling permit is one of the permits required to carry out the Diffuser Project, and for CEQA purposes the Board of Supervisors is a responsible agency.
Discussion:
Delta Pond at the City of Santa Rosa’s Laguna Treatment Plant (LTP) is used to store tertiary disinfected recycled water. When necessary, discharge of recycled water is conveyed from Delta Pond into Santa Rosa Creek near its confluence with the Laguna de Sant Rosa via a series of valves called the Delta Diffuser.
Originally constructed in 2010, the Diffuser was installed in Santa Rosa Creek, which is a natural tributary of the Russian River. Over the winter season, the occurrence or lack of multiple large flow events can have a significant effect on the amount of material transported from or deposited around the Diffuser. Infrequent use of the Diffuser may exacerbate the impacts of natural sediment accumulation; because LTP’s recycled water supply typically goes to beneficial use, the Diffuser may go unused for several years. In recent years, accumulated sediment has been observed fully encompassing the existing duckbill check valves, impeding the discharge capacity of the facility.
It is proposed that approximately 300 cubic yards of accumulated sediment surrounding the Diffuser will be removed by a combination of mechanical and hydraulic dredging techniques. These techniques will likely require more time than fully mechanical means, but will significantly reduce the risk of damaging the Diffuser facility. The mechanically dredged material will be loaded into haul trucks, which will drive to the Soil Handling Area as shown on the Project Exhibits, and then hauled to an approved disposal site. The hydraulically dredged material will be pumped into Geotubes located in the Soil Handling Area, and will be disposed of appropriately after the material has dried.
On January 20, 2022, pursuant to CEQA, the City of Santa Rosa as CEQA lead agency adopted a Mitigated Negative Declaration (MND), which included mitigation measures to reduce environmental impacts to a level of less than significant, and environmental findings for the Delta Pond Discharge Diffuser Maintenance Project at the City’s Laguna Treatment Plant. The City approved the Diffuser Project in the same hearing on January 20, 2022. The requested roiling permit is one of the permits required to carry out the Diffuser Project, and the County is a responsible agency for CEQA purposes.
In addition to compliance with the mitigation measures identified in the MND, the applicant will also comply with all protective measures that are required under agreements with the California Department of Fish and Wildlife and North Coast Regional Water Quality Control Board.
The requested roiling permit is one of the permits required to carry out the Diffuser Project, pursuant to Ordinance 3836R (Sonoma County Code § 23-3). The project will not pollute, contaminate or roil the waters of any river or stream. The selected contractor will be required to develop and implement a Storm Water Pollution Prevention Plan. Turbidity containment curtains will be installed in the creek around the area to be dredged to prevent disturbed sediment from being transported downstream. The project is required to complete all instream work by October 15, and complete all project activities by October 31.
Strategic Plan:
N/A
Prior Board Actions:
Roiling Permit ROI10-0003 for the initial construction of the Delta Pond Diffuser was approved by the Board of Supervisors on July 6, 2010.
Fiscal Summary
N/A
Narrative Explanation of Fiscal Impacts:
N/A
Narrative Explanation of Staffing Impacts (If Required):
N/A
Attachments:
1. Board of Supervisors Resolution
2. Application
3. Maps
4. California Fish and Wildlife Authorization
5. North Coast Regional Water Quality Control Board Authorization
6. City of Santa Rosa Mitigated Negative Declaration
Related Items “On File” with the Clerk of the Board:
N/A