Legistar To: The Board of Supervisors of Sonoma County
Department or Agency Name(s): Permit Sonoma
Staff Name and Phone Number: Tennis Wick, (707) 565-1925
Vote Requirement: Majority
Supervisorial District(s): 2
Title:
Title
1:45 P.M. - ZCE15-0008 Zone Change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District; 3083 and 3127 Middle Two Rock Rd, Petaluma
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Recommended Action:
Recommended action
Conduct a public hearing and adopt an Ordinance finding the project exempt from the California Environmental Quality Act and approving a zone change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District from two adjacent parcels at 3083 Middle Two Rock Rd, Petaluma; APN: 021-160-045 and 3127 Middle Two Rock Rd; APN: 021-160-044. (Second District) (Majority Vote Requirement)
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Executive Summary:
The project proposes approval of a Zone Change to remove the Z (Accessory Dwelling Unit Exclusion) Combining District on a 10-acre parcel zoned Diverse Agriculture (DA), located at 3083 Middle Two Rock Rd, Petaluma and a 2.58-acre parcel zoned Diverse Agriculture (DA), located at 3127 Middle Two Rock Rd, Petaluma, approximately 3 miles west of the City of Petaluma. The subject parcels are both developed with a single-family residence and agricultural accessory structures. The request would allow for an Accessory Dwelling Unit (ADU) to be developed on the subject properties in the future.
The Planning Commission adopted Resolution 24-41 on May 2, 2024, recommending the Board of Supervisors approve the Zone Change to remove the Z Combining District from the subject parcels.
Discussion:
Project Site and Context
The project sites are 10 and 2.58 acres in size and are located on Middle Two Rock Road, approximately 3 miles west of Petaluma. The parcels are both developed with single family dwellings and agricultural accessory structures, and each parcel is served by its own septic system. The parcels share a well, which is located in the northwest corner of the 10-acre parcel.
General Plan and Zoning Discussion
The Z combining district was applied to the subject parcels during the implementation of the 1989 General Plan, which aimed to protect agricultural lands from potential overdevelopment of residential use and conversion to nonagricultural uses. In 2019, the Board of Supervisors adopted Ordinance No. 6285, which removed the “Z” Accessory Dwelling Unit (Z ADU) Exclusion Combining District from approximately 1,924 specified parcels located in the Land Intensive Agriculture (LIA), Land Extensive Agriculture (LEA), and Diverse Agriculture (DA) zoning districts countywide that met screening criteria related to fire hazard zones, biotic habitat, groundwater, traffic, and Land Conservation Contracts. The subject parcels met all the 2019 countywide screening criteria but were excluded because they are located within the Petaluma Nitrate Waiver Prohibition Area.
Applications to remove the Z combining district must be consistent with Article 76 of the Sonoma County Zoning Code, Accessory Dwelling Unit Exclusion Combining District. The proposal to remove the Z (Accessory Dwelling Unit Exclusion) Combining district is recommended because the project addresses the following zoning restrictions:
a) Areas where there is an inadequate supply of water for drinking or firefighting purposes.
The parcels are located within a Class 2 Groundwater Availability Area, which is designated as a major natural recharge area.
b) Areas where there are inadequate sewer services or danger of groundwater contamination.
The parcels are located in the Petaluma Nitrate Waiver Prohibition Area, which was implemented in 1980 after groundwater contamination in the area became significant enough to threaten public health and safety. The 10-acre parcel has a 4-bedroom mound septic system approved by SEP15-0276, and the 2.58-acre parcel will have a 3-bedroom septic system, pending final approval of SEP15-0448. The existing septic capacity meets the demand for the single-family dwellings and accessory structures already present on the subject properties. Any increases in septic capacity must be approved by the Permit Sonoma Well and Septic division, and a new septic system would need to meet special standard requirements for the Petaluma Nitrate waiver prohibition area, as described in the Onsite Wastewater Treatment System (OWTS) Manual.
There are no existing groundwater contamination issues on the subject parcels that would prevent the construction of an ADU. Testing conducted on the existing well water in 2019 found arsenic and nitrate levels below state and federal Maximum Contaminant Level (MCL) standards. Additionally, no E. coli was detected in the water sample.
c) Areas where the addition of accessory dwelling units would contribute to existing traffic hazards or increase the burden on heavily impacted streets, roads or highways.
Both parcels are located on Middle Two Rock Road, which is maintained by the County, and have adequate ingress and egress through private driveways. The potential addition of an ADU to each parcel is not expected to contribute to existing traffic hazards or increase the burden on surrounding roadways.
d) Areas where, because of topography, access or vegetation, there is significant fire hazard.
The subject parcels are located entirely within the Moderate Fire Hazard Severity Zone, as defined by the 2023 Fire Hazard Severity Zone (FHSZ) Map. The parcels are relatively flat, and vegetation is concentrated around a small, unnamed riparian area running through the center of the 10 acre parcel. Any future building permits would be required to comply with Fire Safe Regulations for new development, including access, water supply, property line setbacks, construction techniques, and defensible space.
Per County Code Sec. 26-28-160, vacation rentals are not permitted within ADUs.
Additionally, the subject parcels do not meet the criteria to allow development of a new agricultural employee dwelling unit. Additional details on this proposal are available in the attached Planning Commission Staff Report dated May 2, 2024 (Attachment 2).
When the Planning Commission recommended approval of Zone Change request ZCE15-0008 on May 2, 2024, the subject parcels were zoned DA B6 10 Z. The Oak Woodland Ordinance No. 6469, which was adopted by the Board of Supervisors on April 16, 2024 and went into effect on May 16, 2024, applied the OAK (Oak Woodland) Combining District to the 10-acre parcel at 3083 Middle Two Rock Rd, Petaluma. The OAK (Oak Woodland) Combining District does not impact the eligibility for removal of the Z (Accessory Dwelling Unit Exclusion) Combining District for the 10-acre parcel. Any future development on the parcel, such as construction of an ADU, will be subject to the tree protection and mitigation requirements provided under the OAK (Oak Woodlands) Combining District. Staff has updated the proposed Ordinance (attachment 1) to reflect the current zoning of the 10-acre parcel.
Public Comments
Staff received two public comments (Attachment 8), one of which raised concerns about impacts to agriculture, water availability in the area, fire risk, and access improvements and maintenance. The second comment was in support of the zone change request, and noted that the zoning of many of the parcels in the surrounding area allows property owners to build an ADU.
Strategic Plan:
Not Applicable
Racial Equity:
Was this item identified as an opportunity to apply the Racial Equity Toolkit?
No
Prior Board Actions:
Not Applicable
Narrative Explanation of Fiscal Impacts:
No fiscal impact
Narrative Explanation of Staffing Impacts (If Required):
Not Applicable
Attachments:
ATT 1 ZCE15-0008 Board of Supervisors Ordinance
ATT 1a ZCE15-0008 Existing and Proposed Zoning Map
ATT 2 ZCE15-0008 Planning Commission Staff Report
ATT 3 ZCE15-0008 Planning Commission Actions and Resolution
ATT 4 ZCE15-0008 Project Proposal Statement
ATT 5 ZCE15-0008 Project Site Plan
ATT 6 ZCE15-0008 Groundwater Availability Map
ATT 7 ZCE15-0008 PowerPoint Presentation
ATT 8 ZCE15-0008 Public Comments
Related Items “On File” with the Clerk of the Board:
None