The purpose of this chapter is to categorize hillsides into five slope categories and establish limits on land use density. Additional design standards and guidelines are provided in article VII (Design Standards and Guidelines). The development and density limits established in this chapter apply based on the location of property with five established slope zones (section 17.52.020).
(Ord. No. 1000 § 4, 2022)
All property within the city can be categorized into one of the following slope zones. Regulations apply as indicated.
A. 
Zone 1 (five percent natural slope or less). This is not a hillside condition. Grading with conventional fully padded lots and terracing is acceptable.
B. 
Slope Zone 2 (five percent to 7.99 percent slope). Development with grading is permitted in this zone, but existing landforms must retain their natural character. Padded building sites are permitted; however, techniques such as contour grading, combined slopes, limited cut and fill, and split-level architectural prototypes, or padding for the structures only, may be required to reduce grading.
C. 
Slope Zone 3 (eight percent to 14.9 percent slope). This is a hillside condition. Special hillside architectural and design techniques (see article VII (Design Standards and Guidelines)) that minimize grading are required in this zone. Architectural prototypes are expected to conform to the natural landform by using techniques such as split-level foundations of greater than 18 inches, stem walls, stacking, and clustering.
D. 
Slope Zone 4 (15 percent to 29.9 percent). Development within this zone is limited to no more than the less visually prominent slopes and then only where it can be shown that safety, environmental, and aesthetic impacts can be minimized. The use of larger lots, variable setbacks, and variable building structural techniques such as stepped or pole foundations are expected. Structures shall blend with the natural environment through their shape, materials, and colors. Impact of traffic and roadways is to be minimized by following natural contours or using grade separations.
E. 
Slope Zone 5 (30 percent and over). This is an excessive slope condition and development is prohibited, unless all the following are satisfied:
1. 
The property is located south of Banyan Street;
2. 
At least 75 percent of the lots or parcels that are the subject of the development application are surrounded by lots or parcels improved with structures;
3. 
The proposed project is determined to appropriately address slope stability and other geological factors of the site; and
4. 
Vegetation fuel management for wildfire protection can be achieved and maintained.
(Ord. No. 1000 § 4, 2022)
This section correlates the steepness of the terrain with limitations on development intensity. The total allowable residential dwelling units shall be calculated based on the total (buildable) land area within each slope category multiplied by the capacity factor for each to the slope category.
A. 
Using the land capacity schedule. Table 17.52.030-1 (Land Capacity Calculation) converts the amount of gross site acres into the amount of net buildable acres based on slope measurement.
TABLE 17.52.030-1 LAND CAPACITY CALCULATION
Land capacity formula: (Acreage of _% slope) x (Capacity ratio) = Net buildable area
Slope Measurement
Acres of Land (Gross)
Capacity
Ratio (x)
Adjusted Net Buildable Area (Acres × Capacity Ratio)
Under 10%
A
1.000
Ax
10-14.9%
B
0.750
Bx
15-19.9%
C
0.500
Cx
20-24.9%
D
0.250
Dx
25-29.9%
E
0.025
Ex
+30%
F
0.000
Fx
Total 
(Ax + Bx + Cx + Dx + Ex + Fx)
B. 
Calculating permitted units. The maximum number of dwelling units that may be permitted in a proposed development shall be determined by multiplying the total adjusted net buildable area (Ax + Bx + Cx + Dx + Ex + Fx) above by the permitted number of allowed units per acre according to the zone.
C. 
Exceptions. The following land areas, meeting any or all of the following criteria, shall not be included in the calculation of total allowable dwelling units:
1. 
All land areas, regardless of slope, which will be subject to inundation during a 100-year storm after development has occurred.
2. 
All land which is in a geologic hazard zone, as defined in the public health and safety chapter of the general plan of the city, and for which no feasible mitigation measures are proposed.
3. 
All land area which lies within a federally recognized blue line stream or contains significant riparian or streambed environs.
4. 
All the following are satisfied:
a. 
The property is located south of Banyan Street;
b. 
At least 75 percent of the lots or parcels that are the subject of the development application are surrounded by lots or parcels improved with structures;
c. 
The proposed project is determined to appropriately address slope stability and other geological factors of the site; and
d. 
Vegetation fuel management for wildfire protection can be achieved and maintained.
(Ord. No. 1000 § 4, 2022)