The following minimum performance standards are required for any development within this Overlay zone. Necessary information shall be provided with the Conditional Use Permit application as prescribed in Chapter 19.36 to determine compliance with these standards.
1. SOILS/GRADING
A. Grading of any site shall conform to the following grading standards, based upon the percent of the natural slope. The City Engineer shall review and make recommendation to the Planning Commission on the proposed grading.
1. 0 - 15%.
Redistribution of earth over large areas may be permitted.
2. 15+ - 25%.
Some grading may occur, but landforms must retain their natural character. Padded building sites may be allowed, but custom foundations, split level designs, stacking and clustering is expected to mitigate the need for large padded building areas.
3. 25+ - 30%.
Limited grading may occur, however, major topographic features shall retain their natural landforms. Special hillside architectural and design techniques are expected in order to conform to the natural land form, by using techniques such as split level foundations of greater than 18 inches, stem walls, stacking and clustering.
4. Greater than 30%.
Development and limited grading can only occur in this category if it can be clearly demonstrated that safety, environmental, and aesthetic impacts will be avoided. 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.
B. Grading shall be designed to:
1. Conserve natural topographic features and appearances by means of land sculpturing to blend graded slopes and benches with natural topography.
2. Retain major natural topographic features such as canyons and prominent landmarks.
C. All graded areas shall be protected from wind and water erosion through acceptable slope stabilization methods such as planting, walls, or netting. Interim erosion control plans shall be required, certified by the project engineer, and reviewed and approved by the Public Works Department.
D. Slopes created by grading of the site shall not exceed 50 percent or 2:1, without a soils report and stabilization study indicating a greater permissible slope; or shall not exceed 30 feet in height between terraces or benches; except that the Planning Commission may permit slopes exceeding these dimensions where the slopes will result in a natural appearance and will not create geological or erosion hazards.
2. PUBLIC SAFETY
A. FIRE SAFETY
All developments in this overlay zone shall comply with the standards of the FF (Foothill Fire Zones) Overlay. In the course of the review for a project in this overlay zone, the City will be reviewing each project to determine compliance with fire safety standards. The standards cover such items as, but not limited to:
1. Number of access points and street designs for each development;
2. Driveway lengths and widths;
3. Distances between dwellings;
4. Fuel modification plan;
5. Water flow and fire hydrant requirements;
6. Fire retardant building materials;
7. Residential sprinkler requirements as provided in the Foothill Fire Zone
Overlay standards.
B. GEOTECHNICAL
1. Any subdivision within the Alquist-Priolo "Special Studies Zone" shall conduct a geologic study in conformance with the requirements of the Zone. This study shall be prepared by a certified engineering geologist.
2. No structure for human occupancy shall be permitted within 50 feet of an active or potentially active fault trace. Sensitive and high occupancy structures as defined in the General Plan shall maintain a minimum 100 foot setback.
3. No emergency facilities, community facilities, or places of general public assembly (not including open space areas) shall be permitted within the Alquist-Priolo Zone.
4. All structures within the trace shall require the seismic features of the structure to be reviewed and approved by a professional engineer specializing in seismic/structural design.
5. The Building Official may require special construction methods of structures where it has been determined to have potential geologic hazards.
6. A statement shall be included at the time of purchase agreement and at the close of escrow to the purchaser of each lot within the development, which informs the prospective owner of the potential for seismic activity, and the potential hazards.
3. WATER/DRAINAGE
A. On-site catch basins or siltation basins, as well as energy absorbing devices, may be required as a means to prevent erosion as well as to provide for ground water recharge.
B. Natural drainage courses should be protected from grading activity.
C. Where brow ditches are required, naturalize with plant materials and native rocks.
D. Maximum coverage of a parcel by impervious surfaces shall not exceed 40% of the gross land area, and such maximum may be reduced by the Director in areas where the slope exceeds 15%.
4. ANIMAL AND PLANT LIFE
A. Areas of a site which are identified in the environmental study as having biological significance shall be preserved, unless exempted by the Planning Commission through the Conditional Use Permit process.
B. Natural vegetation shall be maintained wherever possible. If removal is required, reestablishment of a compatible plant material will be required at a ratio of at least 2:1.
C. All exposed slopes and graded areas shall be landscaped with ground cover, shrubs, and trees.
D. Existing mature trees shall be incorporated into the project where feasible.
E. Water and energy conservation techniques shall be utilized, such as special irrigation techniques (e.g., drip irrigation), drought tolerant plant species, alluvial rockscape, etc.
F. Wherever possible, fire resistant native vegetation shall be preserved and planted.
G. Introduction of landscaping within the hillside areas should make maximum use of texture, color, and be capable of blending in with the natural landscape, and help to soften the effects of buildings, walls, pavement, and grading.
H. Screening along roadways should make maximum use of berming and landscaping but shall not interfere with sight distance.
5. DESIGN
A. Dwelling units and structures shall be compatible with the natural surroundings of the area and shall not dominate the natural environment.
B. Exterior finishes of dwelling units and structures should blend in with the natural surroundings by using earth tone colors and avoiding reflective materials or finishes.
C. Site design should utilize varying setbacks, building heights, innovative building techniques, and building and wall forms which serve to blend buildings into the terrain.
D. Dwelling units and structures shall be sited in a manner that will:
1. Retain outward views from each unit;
2. Preserve or enhance vistas, particularly those seen from public places;
3. Preserve visually significant rock outcroppings, natural hydrology, native plant materials, and areas of visual or historical significance.
E. The highest point of any structure shall not be located above the ridgeline. A ridgeline is a long, narrow, conspicuous elevation which is visible north of Highland Avenue, from a freeway, major arterial, secondary arterial, or collector street, which forms part of the skyline or is seen as a distant edge against a backdrop of land at least 300 feet horizontally behind it. (See graphic.)
1. Use the natural ridgeline as a backdrop for structures;
2. Use landscape plant materials as a backdrop; and
3. Use the structure to maximize concealment of cut slopes.
F. Retaining Walls/Fences
1. Retaining walls shall be used in the following manner:
Upslope - One wall per lot not exceeding eight feet in height.
Downslope - One wall per lot not exceeding 42 inches in height may be used.
Lots sloping with the street of access or other conditions - One retaining wall on each side of the lot may be used not exceeding 42 inches in height.
Retaining walls adjacent to driveways - Walls being an integral part of the structure may exceed 8 feet in height if necessary.
2. Exposed retaining walls facing roadways shall be no greater than 5 feet in height.
3. Where retaining walls face roadways, they shall be faced with aesthetically pleasing materials (e.g., rock facing).