Demson Tree Removal Permit, Site Plan Review, and Design Review (P5570)(P5571)

The applicant requests Tree Removal Permit, Site Plan Review, and Design Review approvals to remove Protected and Heritage trees and to construct a primary residential structure (i.e., single-family residence) and associated infrastructure on a vacant lot possessing a Stream Conservation Area (SCA) in the unincorporated community of Forest Knolls.

The proposed tree removal activities would consist of the removal of eleven regulated trees classified as Protected or Heritage pursuant to the definition of "Protected Tree and Heritage Tree" set forth in Marin County Code Section 22.130.030 (Definitions of Specialized Terms and Phrases). These removals would occur primarily near the center of the subject lot, with additional isolated removals at the northeast and southwest corners, as well as one removal located just beyond the southeast corner of the property. According to the Tree Survey Report prepared by WRA Environmental Consultants, Inc. (dated September 2025), and the Existing Site Plan on Sheet A100 prepared by Bernard Architects (dated September 2025), the proposed removals include ten Protected and one Heritage Douglas-fir (Pseudotsuga menziesii). These trees are listed in a chart below that includes their identification number from the arborist report, health assessment, total observed diameter at breast height, and other relevant information.

The proposed residential development would consist of a 4,314-square-foot single-family residence and associated infrastructure that would be partially located within the Stream Conservation Area (SCA), as depicted in the plan set prepared by Bernard Architects.

The proposed single-family residence would result in a floor area ratio of 22 percent on the 19,999-square-foot lot, pursuant to the definitions of “Floor Area” and “Floor Area Ratio” set forth in Marin County Code Section 22.130.030 (Definitions of Specialized Terms and Phrases). The residence would reach a maximum height of 33 feet above grade, based on the information provided on the Proposed Site Plan (dated September 2025) on Sheet A101 of the submitted plan set. It would also maintain the following minimum setbacks, as measured from the Proposed Site Plan pursuant to Marin County Code Section 22.20.090(B) (Measurement of Setbacks): 30 feet to the western front property line; 112 feet, 11 inches to the southern side property line; 18 feet, 11 inches to the northern side property line; and 21 feet, 1 inch to the eastern rear property line.

The associated infrastructure includes, among other improvements, a proposed retaining wall system reaching maximum heights of 11 feet, 11 ½ inches above grade, as shown on the Proposed Site Plan on Sheet A101. The system would maintain the following minimum setbacks, as measured pursuant to Marin County Code Section 22.20.090(B) (Measurement of Setbacks): 4 feet, 2 inches from the southern side property line; 14 feet, 3 inches from the northern side property line; and 13 feet, 10 inches from the eastern rear property line. The system would have a minimum front-yard setback.

The proposed residential development would also entail various other improvements, including site grading (approximately 1,243 cubic yards of cut, 280 cubic yards of fill, and 960 cubic yards of off-haul); utility systems, such as an on-site wastewater disposal (septic) system; recreational amenities, such as a spa; structural improvements, such as attached decks and porch; access and hardscaping, such as a driveway, patios, and stairways; and landscaping and aesthetic enhancements featuring native and nonnative plantings.
 

Tree Removal Permit approval is required pursuant to Section 22.62.020 of the Marin County Development Code because the project involves the removal of Protected and Heritage trees, as defined in Section 22.130.030 (Definitions of Specialized Terms and Phrases), on a vacant lot.

Site Plan Review approval is required pursuant to Section 22.52.020(F) of the Marin County Development Code because the project proposes certain development-related activities, such as removing vegetation, disturbing soil, and increasing surface runoff, within a Stream Conservation Area located in the San Geronimo Valley (SGV) Combining District.

Design Review approval is required pursuant to Section 22.42.020(B) of the Marin County Development Code because the project proposes to construct residential development exceeding 3,500 square feet of floor area on a lot in a Conventional zoning district.

Design Review approval is required pursuant to Section 22.42.020(D) of the Marin County Development Code because the project proposes to construct single-family residential development and associated improvements on a vacant lot that is 50 percent smaller in total area than required for new lots under the applicable slope regulations.

Design Review approval is required pursuant to Section 22.54.045(F) of the Marin County Development Code because the project proposes to construct a retaining wall (i.e., detached accessory structure) that would exceed the maximum height limit for such improvements, as established in Section 20.20.052 (Retaining Wall Standards).

Zoning:  R1-B3-SGV (Residential, Single-Family District with the Minimum Lot Size “-B3” Combining District and the San Geronimo Valley Combining District)
Countywide Plan Designation:  SF4 (Rural / Residential)
Community Plan (if applicable):  San Geronimo Valley Community Plan (1997)