A. Hillside Slope Categories. The following descriptions serve as general standards for hillside slope categories to ensure that development will compliment the overall character of the landform.
DEVELOPMENT STANDARDS
% Natural Slope Category | Standards |
Up to 25% | This is not considered a hillside condition. |
25% up to 50% | This is a hillside condition. Development within this slope category is limited to the less visually prominent slopes, and then only where it can be shown that grading, vegetation removal, safety and environmental and aesthetic impacts can be minimized. Impact of access and roadways shall be minimized by following natural contours or using grade separations. Structures shall blend with the natural landform through their shape, material, and color. Special hillside architectural and design techniques are required, which may include the use of larger lots, variable setbacks, and variable building structural techniques and clustering. Padded building sites may be considered in some instances. Where this occurs, the commission may consider padded building sites adjacent to special features when it is found that grading of padded building sites will create a better relationship between the special feature(s) and the building sites. |
50% and over | This is an excessive slope condition and development is prohibited. |
B. Site Design.
1. Projects located in hillside areas shall incorporate clustering, variable setbacks, multiple orientations, and other site planning techniques to preserve open spaces, protect natural features, and offer views to residents.
2. When clustering techniques are used, minimum lot sizes may be decreased to five thousand (5,000) square feet when it is necessary to preserve sensitive lands (e.g., hillsides, creeks, habitat areas, etc.). Lots may be allowed smaller than five thousand (5,000) square feet, but not smaller than four thousand (4,000) square feet, for up to twenty (20) percent of the total approved lots and only under an approved specific plan when absolutely necessary to preserve sensitive and hillside areas. Lots under five thou-sand (5,000) square feet are prohibited in slope areas of twenty-five (25) percent or greater.
C. Driveways and Roadways.
1. Driveways shall enter public/private streets maintaining adequate sight distance as determined by the city engineer.
2. Driveways shall not be located within three feet of a side property line. Exceptions may be considered based on lot size, percent slope, appropriate drainage facilities and use as a common (joint) driveway.
3. Only slopes less than fifty (50) percent (2:1) shall be allowed adjacent to driveways.
4. Driveway grades above fifteen (15) percent may only be considered when driveways are aligned with the natural contours of the land, are necessary to achieve effective site design, and safety considerations are met to the satisfaction of the building and safety official, city engineer, and the fire department. Proper design considerations shall be employed, including the use of vertical curves. On driveways that may be approved with a slope greater than fifteen (15) percent, a coarse, all-weather paving material, or grooves for traction, shall be incorporated into the construction.
5. Roadways shall conform to the natural landform. Significant alterations to the physical and visual character of a hillside shall be avoided by eliminating large notches in ridgelines and wide straight alignments. Modified or reduced width road sections and split sections shall be considered in the layout of hillside streets to reduce grading and cuts in topography while allowing access for fire trucks and other emergency vehicles.
6. Where road construction is proposed in hillside areas, the standards shall be consistent with those identified for high fire hazard areas.
7. The extent of vegetation and visual disruption shall be minimized by the combined use of retaining structures and regrading to approximate natural slopes. The view along a street front shall provide a pleasant appearance with a sense of open space and landscaping. The use of terraced walls and landscaping to reduce grading impact associated with retaining walls is encouraged.
8. Wet utilities shall be placed in the road right-of-way, where feasible.
9. Appropriate roadway drainage and grades shall be provided.
D. Architecture.
1. The building envelope for primary structures, except for padded building sites, shall be as follows:
a. Downhill Lot. The maximum structure height shall be thirty (30) feet, measured from finished grade at the front setback line extending towards the rear of the lot. The maximum height at the side setbacks shall be fifteen (15) feet extending up toward the center of the lot at a forty-five (45) degree angle to a maximum height of thirty (30) feet as measured from finished grade.
FIGURE 3-4
BUILDING ENVELOPE FOR DOWNHILL LOT
BUILDING ENVELOPE FOR DOWNHILL LOT
b. Uphill Lot. The maximum structure height shall be fifteen (15) feet, measured from finished grade at the front setback line extending up towards the rear of the lot at a forty-five- (45-) degree angle to a maxi-mum height of thirty (30) feet. The maximum height at the side setbacks shall be fifteen (15) feet extending up towards the center of the lot at a forty-five- (45-) degree angle to a maximum height of thirty (30) feet as measured from finished grade.
FIGURE 3-5
BUILDING ENVELOPE FOR UPHILL LOT
BUILDING ENVELOPE FOR UPHILL LOT
c. Cross Slope Lot. The maximum structure height shall be thirty (30) feet, measured from finished grade at the maximum front setback line extending towards the rear of the lot. The maximum height at the side setbacks shall be fifteen (15) feet extending up towards the center of the lot at a forty-five-(45-) degree angle to a maximum of thirty (30) feet as measured from finished grade.
FIGURE 3-6
BUILDING ENVELOPE FOR CROSS LOT SLOPE
BUILDING ENVELOPE FOR CROSS LOT SLOPE
d. Architectural Projections Allowed. Architectural projections and variations in roof design are encouraged. Projections above the maximum height limits for architectural features may be allowed subject to approval by the director.
2. In steeper terrain, reduction of front yard setbacks may be considered in order to minimize rear yard grading.
3. Architectural treatments shall be provided on all sides of a structure. Elements of the architectural treatment used on the front facade shall be repeated on all sides of a structure with additional emphasis on those elevations visible from public rights-of-way.
4. Building materials and color schemes shall blend with the natural landscape. Colors shall be earth tones and the value (lightness or darkness) of the specific hue shall be as close to that of the immediately surrounding landscape as possible. Where exterior stucco is used, it shall have a final coat of integrated color in a muted earth tone. Contrasting color accents shall be kept to a minimum.
5. Treated wood or materials of a wood-like appearance, having the necessary fire retardant characteristics. are encouraged for exterior surfaces. Use of other natural materials (e.g., river rock) is also strongly encouraged. The reflectivity of exposed surfaces (walls, roofs, windows, frames, and paved surfaces) shall be mitigated by overhangs, trellises, planting, and similar features.
6. Exterior lighting shall be located and shielded so as to not impact adjacent property owners in terms of glare and privacy in compliance with Section 16.18.100 (Lighting).
E. Walls and Fences.
1. Retaining walls, not exceeding six feet in height, may be allowed to reduce grading, preserve natural features, or increase soil stabilization. Within the required front yard setback, individual retaining walls shall not exceed three feet in height.
2. Where multiple (terraced) walls are designed to retain larger slopes they shall not exceed six feet in height and shall be separated by a minimum of six feet horizontally. A maximum of two walls shall be placed together. Walls within the required front yard setback shall not exceed three feet in height and shall be separated by a minimum of three feet and shall incorporate landscaping to screen the wall(s).
FIGURE 3-7
HEIGHT OF RETAINING WALLS
HEIGHT OF RETAINING WALLS
3. Walls that are an integral part of the primary structure may exceed six feet in height; however, their visual impact shall be mitigated through contour grading and landscape treatment.
FIGURE 3-8
RETAINING WALL AS PART OF PRIMARY STRUCTURE
RETAINING WALL AS PART OF PRIMARY STRUCTURE
4. Crib walls may be approved on a case by case basis if it can be demonstrated that excessive height is not being created and provisions for extensive landscaping are incorporated.
5. Walls and fences shall incorporate materials and colors used in an adjacent structures. Naturally occur-ring materials (e.g., river rock, flagstone, etc.) shall be used whenever possible.
6. Walls and fencing visible from the public right-of-way shall be designed to incorporate visual interest through variation in placement, use of planters, differing materials, and modulation of the wall plane.
7. Walls and fences shall follow landform grading shapes and contours.
E. Landscaping. Revegetation in hillside areas shall reflect the visual patterns found naturally in local canyons and valleys. The landscaping as viewed from urban areas and arterial roadway system shall mask and screen man-made structures.
1 . Indigenous, or naturalized plants that blend naturally with the landscape shall be utilized in areas where planting is required.
2. Natural landform planting shall be used to soften manufactured slopes, reduce the impact of development on steep slopes or ridgelines. and provide erosion control. These landscape techniques shall serve to reintroduce landscape patterns that occur naturally in the hillsides.
3. A "vegetative backdrop" shall be maintained by replanting with native trees or the same vegetation that was removed. The vegetation should screen structures to the extent possible at maturity and preserve the appearance of the natural skyline.
4. The surface of graded or disturbed slopes with three feet or greater vertical height shall be protected against damage by erosion through the planting of deep rooted ground cover. Slopes exceeding eight feet in vertical height shall be planted with ground cover and a combination of shrubs and trees that have a high "root-to-shoot" ratio. The size of shrubs and trees shall be determined based on the individual project area as deemed appropriate by the department and/or commission.
5. Jute mesh or an equivalent shall be required when planting occurs between August fifteenth and April fifteenth, and when determined, as necessary, by a soils engineer and/or licensed landscape architect.
6. Indigenous, native vegetation shall be retained and supplemented within canyons and along natural drainage courses where grading does not occur, provided that it conforms with fuel modification and tire prevention plans.
7. Common open areas and front and side yards adjacent to a street shall be adequately landscaped and irrigated. The areas shall be provided with native plant materials that blend with the natural character of the surrounding landscape.
8. In order to protect slopes from soil erosion and slippage and to facilitate revegetation, an automatic irrigation system shall be installed on slopes with planting. Design and operation of the irrigation system shall respect the special conditions that exist in hillside situations specific to maintaining slope stabilization and integrity. In all cases, the emphasis shall be toward using plant materials that may eventually not need to be irrigated: therefore, temporary irrigation systems may be used as approved by the city's landscape architect and city engineer. Water and energy conservation techniques shall be utilized (e.g., drip irrigation, alluvial rockscape, etc.) Where irrigation systems are installed above ground, ultraviolet light resistant. brown line or other approved color, shall be used.
9. A permanent fuel modification area shall be required around development projects that are adjacent or exposed to hazardous fire areas for the purpose of fire protection. The fuel modification area shall be maintained by its owners, a homeowners' association, or other public nonprofit agency or conveyed in a public easement. Adequate provisions shall be made for the continual maintenance of these areas and the fire chief may require brush, vegetation, or debris to be removed and cleared consistent with the provisions of Chapter 8.32 of the municipal code. Where feasible, fuel modification areas shall be designated as common open space rather than private open space. The recommended width of the fuel modification area shall be based on applicable building and fire codes and the recommendations of the fire chief with consideration given to:
a. A worst-case Santa Ana wind condition;
b. The natural ungraded slope of the land within the project and in the areas adjacent to the project;
c. Fuel loading:
d. Access to the project by fire suppression equipment. and access directly to the fuel modified area, and egress out of the project in case of evacuation;
e. The on-site availability of water that can be used for fire fighting purposes with regard to fire flows, water pressure, and duration:
f. "Built-in" fire protection within structures (i.e., sprinklers etc.);
g. Soil erosion and sediment control measures; and
h. The fire department fuel modification policy document.
10. Fuel modification areas shall also incorporate soil erosion and sediment control measures to alleviate permanent scarring and accelerated erosion.
G. Grading.
1. Grading shall not take place on natural slopes that exceed fifty (50) percent.
2. Slopes created by grading of the site shall not exceed fifty (50) percent or 2:1, without a soils report and stabilization study indicating a greater permissible slope. Slopes shall not exceed thirty (30) feet in height between terraces or benches, except that the commission may permit slopes exceeding these dimensions where the slopes will result in a natural appearance and will not create geological or erosion hazards. The soils report and stabilization study will be subject to third party review prior to approval by the city. Refer to the hillside development guidelines (16.24.070) for methods to accomplish this standard.
3. Structures shall not visually impair ridgeline silhouettes. Structures are not permitted closer to a prominent ridge than fifty (50) feet measured vertically on a cross-section or one hundred fifty (150) feet horizontally on a topographic map. whichever is more restrictive. Exceptions to this requirement for public facilities. utilities. and infrastructure necessary to serve the public health, safety, and welfare may be considered by the commission.
4. Clearing, excavation, or other earth disturbances shall not be permitted on hillside areas prior to the issuance of a grading permit. with the exception of county/state authorized soils remediation operations, drill holes, and exploratory trenches for the collection of geologic and soil data. Trenches are to be properly backfilled and in addition, erosion treatment provided where slopes exceed twenty-five (25) percent.
5. Manufactured cut and fill slopes exceeding ten feet in height which will be either exposed to public view, or are adjacent to environmentally sensitive areas, shall be landform or contour graded, where physically feasible, so that their ultimate appearance will resemble a natural slope. This will include slopes along streets and highways, slopes, adjacent to parks, schools, open spaces, and other public facilities and other prominent slopes. Refer to the hillside development guidelines (16.24.070) for methods to accomplish this standard.
6. Landform grading shall be used where zero to twenty-five (0-25) percent (nonhillside) slopes intersect with twenty-five to fifty (25-50) percent (hillside) slopes. Proper transitioning from manufactured slopes created by conventional grading methods to natural slopes shall be achieved gradually and naturally through the use of radii or irregular curvilinear shapes that will blend into the adjoining topography tangentially and not create abrupt changes.
7. Fill slopes shall not be placed perpendicular across a canyon. Straight line cut ofF fill slopes shall not be made to appear like a dam. The terminus of the fill shall, instead, be concave in shape to restore the can-yon appearance. This concave configuration shall be in combination with the use of substantially flatter slope ratios (4:1, 3.5:1, 3: I ) at or near the center of this indentation. Symmetrical or unsymmetrical con-cave configurations shall be used depending upon the adjoining or underlying topographic characteristics.
8. Minimal radius rounding at the edges of cut and fill slopes is not acceptable. Proper transitioning from manufactured slopes to natural slopes shall be achieved gradually and naturally through the use of radii or irregular curvilinear shapes that will blend into the adjoining topography tangentially and not create abrupt changes.
9. In the planning, design, and development of public utilities and infrastructure, every reasonable effort shall be made to minimize grading impacts and harmonize with the natural contours and character of the land.
10. Side yard slopes and low (less than twenty (20) feet in height) rear yard slopes whose view is blocked by future structures need not have landform design applied.
11. Grading shall be phased so that prompt revegetation or construction will control erosion. Where possible. only those areas that will be built on, resurfaced, or landscaped shall be disturbed. Top soil shall be stockpiled during rough grading and used on pads or revegetated habitat areas, upon the recommendation of the soils engineer. Refer to the hillside development guidelines for methods to accomplish this standard.
12. Applicable requirements of the city and state shall be complied with in conjunction with a National Pollution Discharge Elimination System (NPDES) permit prior to the issuance of a grading permit, which may include, but is not limited to, an Erosion Control Plan, Best Management Plan (including Notice of Intent to be filed with the state Water Resources Control Board) and Construction Monitoring Program.
H. Drainage.
1. Debris basins, energy dissipating devices, and down drains shall be provided, where necessary, to reduce erosion when grading is undertaken in the hillside areas. Natural drainage courses should be retained where health and safety are not jeopardized. Drainage courses retained in a natural state shall be protected from grading activity. In instances where a crossing is required. a natural crossing and bank protection shall be preferred over steel and concrete systems. Where drainage structures are required, they shall be naturalized with coloration, plant materials, native rocks and/or concealment with grading techniques.
2. Drainage channels, slope drainage devices, interceptor drains and terrace drains should be placed in less visible locations. Down drains shall be hidden in swales diagonally or curvilinear across a slope face. In this manner they will be built into the overall landform of the slope. They should also receive a naturalizing treatment which may include native rock, colored concrete, and/or landscaping so that the structure appears as an integral part of the environment. In all cases, a concrete liner shall be used in addition to a naturalizing treatment.
3. Cross lot drainage usage shall be minimized. In situations where this is not possible using conventional design. optional techniques (e.g., single loaded streets, reduced densities, etc.) shall be considered. Use of cross lot drainage may be considered only after demonstration that this method will not adversely affect the proposed lots or adjacent properties, and that it is absolutely required in order to minimize the amount of grading which would result with conventional drainage practices.
4. Where cross lot drainage is utilized, the following shall apply:
a. Project Interiors. One lot may drain across one other lot if a maintenance easement is provided within either an improved, open V-swale gutter which has a naturalized appearance, or within a closed drainage pipe that shall be a minimum twelve (12) inches in diameter. This drainage shall be conveyed to either a public street or to a drainage easement. If drainage is conveyed to a private easement, it shall be maintained by its owners or a Homeowners' Association; otherwise. the drain-age shall be conveyed to a public easement. The easement width shall be determined on an individual basis and shall be dependent on appropriate hydrologic studies and access requirements. Irrigation lines shall be placed above swales to minimize the impacts in the event of a system failure. When irrigation lines cross an open V-swale they shall be placed in a galvanized pipe which is to be clamped to the soil on both sides of the swale subject to the review of the director.
b. Project Boundaries. On-site drainage shall be conveyed in an improved open V-swale gutter, which has a naturalized appearance, or within an underground pipe in either a private drainage easement, that is to be maintained by its owners or a homeowners' association, or it shall be conveyed in a public easement. The easement width shall be a minimum often feet. A greater width may be determined necessary on an individual basis and shall be dependent on appropriate hydrologic studies and access requirements.
I. Public Safety.
1. Residential developments shall be constructed in a manner so as to reduce the potential for spread of brushfires as follows:
a. In the case of a conflict where more restrictive provisions are contained in the uniform building code or in the uniform fire code, the more restrictive provisions shall apply.
b. Roofs shall be covered with noncombustible materials (e.g., clay tile, concrete shake, tile, or similar materials). Open ends shall be stopped in order to prevent bird nests, or other combustible material, lodging within the roof and to prevent entry of flames.
c. Exterior walls and fences shall be surfaced with noncombustible or flame resistive materials. Alternate surface materials may be approved subject to the approval of the fire chief and Building Official. Except as otherwise provided herein, exterior walls shall extend to the ground.
d. Balconies. patio roofs, eaves and other similar overhangs shall be of noncombustible or flame resistive materials.
e. Plastic webbing, split or whole bamboo, reed or straw-like materials, corrugated plastic or fiberglass materials, and similar flammable materials are not permitted for use on patio covers.
f. Vents for attics and underfloor areas shall be designed and located to minimize the likelihood of spreading of fire.
g. Chimneys shall be provided with approved spark arresters.
2. Adequate water supply and pressure for proposed development shall be required in compliance with fire department Standards.
3. The fire chief shall require brush, vegetation, or debris to be removed and cleared within ten feet on each side of every roadway and access drive, and may enter upon private property to do so. This requirement shall not apply to single specimens of trees, ornamental shrubbery, or cultivated groundcover provided they do not form a means of readily transmitting fire.
4. If the fire chief determines in a specific case that difficult terrain, danger of erosion, or other unusual circumstances make strict compliance with the clearance of vegetation undesirable or impractical, he or she may suspend enforcement thereof and require reasonable alternative measures designed to advance the purposes of this chapter.
5. Site design shall provide for all-weather equipment access to publicly maintained slope areas for maintenance and emergency purposes.
6. Structures and facilities shall be restricted in geologically hazardous areas.
7. Special construction features shall be required in the design of structures where site investigations con-firm potential geologic hazards.
8. Development not on public sewers shall be permitted only after site specific investigations have been conducted that demonstrate the soils are suitable for on-site wastewater disposal and the disposal of wastewater will not degrade the subsurface water quality.
9. Due to the hazard associated with saturated soils in areas of steep slopes, irrigation systems in critical areas that have the potential for failure in the judgement of the city engineer shall be required to be equipped with potentiometers to make sure that the systems will not operate when there is sufficient moisture in the soil.
(Ord. 182 § 2 (part), 1997)