The hillside development guidelines are intended to illustrate and amplify the appropriate development concepts for hillside areas. The guidelines are not intended to be an exhaustive list of standards, but rather policy statements, to encourage development that is sensitive to the unique characteristics common to hillside properties. The guidelines allow for flexibility and they encourage creativity, especially where a specific plan is prepared. How-ever, the development standards provided in Section 16.24.060 shall be considered as a "benchmark" against which hillside development proposals will be reviewed for compliance with the purposes of this chapter.
The guideline's purpose is to allow for innovative or alternate methods of design in hillside areas. Innovation is encouraged as long as the end result is one that respects the natural character of the hillside and is consistent with the purposes of this chapter and the goals, objectives and policies of the general plan .
Conformance with the guidelines will be incorporated in the preparation and approval of subdivisions and individual site developments. During the application review process, the city will evaluate the consistency of the proposal with the purposes of this chapter. Prior to the start of the design effort, it is recommended that the project design team members read the general plan and become familiar with its policies.
A. Site Design.
1. Design of building sites should be sensitive to the natural terrain. Structures should be located in a way that minimizes grading and preserves natural features (e.g., prominent knolls, ridgelines, etc.)
2. Preserve views of significant visual features, as designated on the hillside overlay zone map, as seen from both within and outside a hillside development. When designing lots and plotting homes, the following provisions should be considered:
a. Dwellings should be oriented to allow view opportunities. even though views may be limited. Residential privacy should not be unreasonably sacrificed; and
b. A significant public vista, skyline, open space corridor, or vertical open space corridor as seen from an interstate, an arterial, or a secondary street should be a major design element in the site planning process.
3. Where possible, graded areas should be designed with manufactured slopes located on the uphill side of structures.
4. To the extent possible. the width of a building, measured in the direction of the slope, should be minimized in order to limit the amount of cutting and tilling and to better "fit" the house to the natural terrain. The degree of slope will dictate how this is accomplished.
5. Clustering of development is encouraged in hillside areas regardless of size. This is particularly important in environmentally sensitive areas in order to reduce the potential for tire hazard, erosion and excess runoff, and to preserve existing natural features and open space.
B. Driveways and Roadways.
1. Driveways that serve more than one parcel are encouraged as a method of reducing unnecessary grading, paving, and site disturbance.
C. Architecture.
1. The form, mass, and profile of the individual buildings and architectural features should be designed to blend with the natural terrain and preserve the character and profile of the natural slope. Techniques that should be considered include:
a. Detaching the garage:
b. Integrating retaining walls into garage walls on sloping lots to reduce grading and minimize visibility of walls: and
c. Including architectural enrichments and variations in roof massing. Roofs should have low profiles to minimize their visual impact. On sloping land, the roof pitch should follow the slope of the hill-side, instead of being perpendicular to the hillside or opposing hillside slope. Care should be taken to avoid the use of gabled ends on downhill elevations. Upper stories should not be cantilevered out of the opposite direction of the hillside slope.
2. The design of the structure should give consideration to the lot's size and configuration in order to avoid the appearance of overbuilding and to minimize the blocking of views. For example, within a development, the majority of the units should not be designed with minimum setback to minimum setback.
3. Large expanses of a single material on walls, roofs, or paving areas should be avoided. Create interesting, small scale patterns by breaking up building mass, varying building materials, and through design and placement of windows and doors. Building plans and elevations should be varied throughout a development to avoid a monotonous "cookie-cutter" look.
D. Walls and Fences.
1. Walls and fences can be used to define a sense of place and create an attractive appearance. However, walls should not dominate a view, and their height should be limited adjacent to a street or trail or within a rear yard. Extensive landscaping should be used to reduce the visual impact of walls. In addition, street front walls should incorporate varying design and natural materials. The use of open view fencing is encouraged, so long as adequate public safety and residential privacy are maintained.
2. When possible, walls and fences should be designed as an integral part of the building in order to minimize the visual impact on surrounding areas.
3. Visually obtrusive solid fencing should be avoided in highly visible areas (unless required for sound attenuation), with the preference being for open (wrought iron) fencing.
E. Landscaping.
1. Street trees should be provided in select areas to enhance the natural character of the areas and create a more rural appearance. Street tree species selection, and spacing of trees, should be sensitive to the context in which they are planted. Species selection should also be respectful of potential impact on infra-structure improvements (i.e. root damage to streets, sidewalks, etc.).
2. Slopes should be designed with informal clusters of trees and shrubs to soften and vary the slope planes, consistent with landform grading concepts.
F. Grading.
There are three distinct types of grading proposed in these guidelines, each with a unique quality, each with an individual and appropriate application. Larger sites will most likely incorporate all three concepts in various parts of the plan.
1. Minimal Grading. This is typically used for large lot single family homes, custom homes with variable foundations that conform to the existing slopes, and other uses that utilize the least amount of grading in order to get the facility and structures built. This technique embraces the following concepts:
a. Grading should be limited to individual flat graded pad areas for residential building sites. Grading should be limited to only the required building areas and adjacent outdoor amenities in steep hillside areas;
b. Foundation systems that require little or no grading are encouraged, forcing the architecture to con-form to the land rather than the land to conform to the dwelling:
c. Roadways, driveways, and individual building pads should be designed to conform with the contours and to attempt to daylight in the center of the road or building pad to ensure a minimum cut and fill situation; and
d. The grading concept minimizes the amount of cubic yards of earth excavated and filled.
2. Contour Grading. This concept results in post-development landforms that exhibit many of the characteristics present within natural landforms. Contour grading is typically used in situations where conventional, terraced, grading with benches and slopes might be used but a "softened" grading look is desired. This would be desirable for areas that are limited in public view (i.e. concealed rear yards). Typically, contour grading can reduce required cut and fill volumes as compared with traditional, terraced, grading. The design elements associated with this type of grading include: (See Figure 3-9)
a. The use of horizontal and vertical curve variations for slope banks creating a curvilinear pattern;
b. Post-development landforms that exhibit natural terrain characteristics (without the heavy modeling effects of landform grading);
c. A general rounding of slopes at slope intersections and transition zones with natural grade;
d. Pad configurations that are curvilinear; and
e. Slopes that are designed with contour grading techniques (e.g., the location of slopes behind structure (not in side yards), slopes in hidden locations, or slopes less than ten feet in height).
FIGURE 3-9
CONTOUR GRADING
CONTOUR GRADING
FIGURE 3-10
LANDFORM GRADING
LANDFORM GRADING
3. Landform Grading. Graded slopes in this category will replicate the irregular shapes of natural slopes. Landform grading techniques should be used whenever slopes are created that will be open to public view. This is particularly true for slopes that exceed ten feet in height.
The intent of these grading guidelines, is to incorporate the basic principles of the landform grading concept as the preferred method in the design and construction of hillside development projects so that they w ill be in harmony with the natural topography and reflect natural plant distribution patterns. (See Figure 3-10)
Landform grading techniques embrace the following concepts:
a. Land plans should flow with the natural topography rather than against it. This means that street pat-terns and building pad configurations follow the underlying topographic features rather than cutting across them:
b. Landform graded slopes are characterized by continuous series of concave and convex forms interspersed with mounds that blend into profiles with varying slope gradients and with significant transition zones between man-made and natural slopes;
c. Pad configurations are irregular. Slope down-drain devices either follow natural lines of the slopes or are tucked away in special Swale and berm combinations in order to conceal the drains from view. Exposed segments in visible areas are treated with natural rock for a more aesthetically pleasing appearance;
d. The technique should be used wherever possible to provide a variety of both slope percentage, slope direction, and topographical detailing in a three-dimensional, undulating. pattern similar to existing terrain: and
e. Manufactured cut and fill slopes exceeding ten feet in height that will be either exposed to permanent public view or are adjacent to environmentally sensitive areas should be designed with features characteristic of natural slopes, where physically feasible so that their ultimate appearance will resemble a natural slope. This will include slopes along streets and highways, adjacent to parks, schools, open spaces. other public facilities, and other prominent and visible slopes.
4. The following basic grading guidelines and techniques serve to implement preferred landform grading techniques and help avoid unnecessary cut and fill:
a. Cuts. When convex shaped natural features. (e.g., protruding minor landforms) are cut, the residual landform should not be a flat slope face, but rather should be restored to resemble the original. This will require more than just rounding at the edges but, in effect, reconfiguring it so the final result will give the appearance of a protruding ridgeline.
b. Use of variable slope ratios. Because Landform grading designs require the use of variable slope ratios at greater than 2:1 and may create valleys or concave indentations on building pad areas, they may result in loss of usable area. In addition, engineering and construction costs may increase. Be-cause of this, segments of a cut or fill slope may be designed with variable slope ratios less than 2:1, but not less than 1.5: I within the following guidelines and subject to third party review at the applicant's expense:
1) A geotechnical engineer shall certify that slopes will meet standard stability requirements;
2) The overall ratio from top to toe will be 2:1 or flatter; and
3) Ratios flatter than 2:1 will also be used in the slope design.
c. Grading operations should be planned to avoid the rainy season, October fifteenth (15th) to April fifteenth (I 5th). Grading permits shall only be issued when a plan for erosion control and silt retention has been approved by the city without regard to time of year.
d. A rounded and smooth transition should be made when the planes of man-made and natural slopes intersect. Where cut or fill conditions are created, slopes should be varied rather than left at a constant angle or create an unnatural, rigid, `'engineered" appearance. The angle of a graded slope should be gradually adjusted to the angle of the natural terrain.
e. Manufactured slopes adjacent to roadways shall be consistent with the landform grading and revegetation technique, where physically feasible to create visually interesting and pleasing streetscapes. The higher the slope becomes, the more important the modeling effect of landform grading becomes.
f. Top of slope berms shall be used to eliminate the possibility of drainage sheet flow over the slope that would potentially cause an unstable condition. Tops of slopes should be rounded in conformance with landform grading techniques, or increased in size to reduce the visual impact of the back of a home.
G. Drainage.
1. Natural drainage courses should be preserved and enhanced to the extent possible. Rather than filling them in, drainage features should be incorporated as an integral part of the project design in order to enhance the overall quality and aesthetics of a site, to provide attractive open space vistas, and to preserve the natural character of the site. Encourage the use of natural drainage courses as natural boundaries between neighborhoods.
2. Storm drainage runoff resulting from project development should be minimized. Where possible, flood control plans for storm waters should encourage the detention of water for percolation in to the ground-water to conserve it for future uses and to mitigate downstream flooding.
(Ord. 182 § 2 (part), 1997)