16.010 Purpose.
This chapter establishes the regulations for development and alteration of properties in hillside and ridgeline areas in order to preserve the essential scenic and natural resources that define the character of Petaluma, and to implement the following General Plan goals and policies:
A. General Plan: Land Use, Growth Management and the Built Environment Element.
1. Preserve the essential scenic and natural resources of the open ridgelines and hillsides that help define the character of Petaluma. Goal 2-G-2
2. Allow development in hillside areas that preserve ridgelines and are site sensitive. Policy 2-P-16
a. Protect unique natural features, including landforms, mature trees and their surrounding habitat, and ridgelines, by requiring location of structures away from these assets.
b. Requiring architectural design that reflects the natural form of the hillside setting in order to minimize visual and environmental impacts.
c. Prevent the significant alteration of hillside topography through grading and paving.
d. Use visually unobtrusive building materials.
3. Retain ridgelines and prominent hillsides as open space through appropriate clustering and/or transfer of density to other parts of a development site. Policy 2-P-17
B. General Plan: Community Design, Character and Sustainable Building Element.
1. Allow for clustering of residential units in the hills, permitting smaller lot sizes where clustering and common space is maintained and proposed development corresponds to stipulated density ranges. Policy 3-P-71
2. Reinforce the existing character of the hillside neighborhoods, preserving topography and ridgelines. Goal 3-G-12
3. Minimize grading, to all extent possible, stepping development into and with the natural topography. Policy 3-P-80
4. Preserve trees and enhance the natural woodland ecology of the South Hills subarea. Policy 3-P-81
C. General Plan: Health and Safety Element.
1. On sites with slopes greater than 30 percent, require all development to be clustered outside of the 30 percent slope areas (and preferably on land less than 15 percent in slope) where possible. Policy 10-P-1
2. Ensure that new development on hillsides is constructed to reduce erosion and landslide hazards and in compliance with any hillside regulations, including but not limited to: Policy 10-P-2
a. Limit cut slopes to 3:1, except where an engineering geologist can establish that a steeper slope would perform satisfactorily over the long term.
b. Encourage the use of retaining walls or rock-filled crib walls as an alternative to high cut slopes.
c. Ensure revegetation of cut-and-fill slopes to control erosion. Plant materials for revegetation should not be limited to hydro-seeding and mulching with annual grasses. Trees add structure to the soil and take up moisture while adding color and diversity.
d. Ensure blending of cut-and-fill slopes within existing contours, and provision of horizontal variation, in order to mitigate the artificial appearance of engineered slopes.
e. Ensure structural integrity of sites previously filled before approving redevelopment.