Chapter 18.36 - Hillside Development Standards

Sections:

18.36.010 - Purpose of Chapter
18.36.020 - Applicability
18.36.030 - Application Content
18.36.040 - Standards for Hillside Development
18.36.050 - Design Criteria for Hillside Development
18.36.060 - Criteria for Use Permit Approval

18.36.010 - Purpose of Chapter

This Chapter establishes regulations for development within hillside areas in order to:

A. Preserve and protect the views to and from hillside areas in order to maintain the identity, image and environmental quality of the Town;

B. Ensure that development in the hillside areas is concentrated on the most level portions of the site, is in locations with the least environmental impact, and is designed to fit the existing land forms;

C. Preserve significant features of the natural topography, including swales, canyons, knolls, ridgelines, and rock outcrops;

D. Correlate intensity of development with the steepness of terrain in order to minimize the impact of grading, unnecessary removal of vegetation, land instability, and fire hazards; and

E. Provide alternative approaches to conventional flat land development practices by achieving land use patterns and intensities that are consistent with the natural characteristics of hillside areas including slopes, land form, vegetation and scenic quality.

18.36.020 - Applicability

A. Hillside area. The standards of this Chapter apply to all uses, subdivisions, and structures proposed on development sites with an average slope of 10 percent or greater or on development sites with any slopes of 20 percent or greater; except that single-family dwellings, secondary residential units, duplexes, and residential accessory structures shall be exempt from the provisions of this Chapter.

B. Basis for slope determinations. For the purpose of this Chapter, slope shall be computed on the natural slope of the land before grading is commenced, as determined from a topographic map having a scale of not less than one inch equals 100 feet and a contour interval of not more than five feet. See Chapter 18.220 (Definitions, Glossary) for definitions on simple slope and complex slope and how to measure slope.

C. Use Permit required. Hillside developments other than subdivisions with any development, including roads, streets, and driveways, proposed on slopes of 20 percent or greater shall be subject to the approval of a Use Permit in compliance with Chapter 18.76. A soil and geotechnical study that identifies special constraints and mitigation measures to minimize grading, unstable soils, and erosion shall accompany the use permit application. The geotechnical study shall also analyze the landslide hazards of the site and their potential effect.

18.36.030 - Application Content

Land use permit and subdivision applications for projects proposed within hillside areas shall include all information and materials required by Section 18.70.040 (Application Preparation and Filing), and all additional information required by the Director on the basis of site topography.

18.36.040 - Standards for Hillside Development

A. Minimum lot area. The minimum lot area for new subdivisions in hillside areas shall be determined by the applicable zoning district, except where housing units are clustered and the project is approved as a Planned Development in compliance with Chapter 18.78.

B. Clustered development required. Proposed hillside development shall be clustered in compliance with Chapter 18.46 (Open Space/Cluster Requirements).

C. Preservation of steep slopes. Slopes of 30 percent or greater shall be permanently preserved as open space. Permanent open space areas may be used in compliance with Section 18.46.060 (Open Space Standards). Grading, structures, and/or streets on slopes exceeding 20% shall be avoided if there is sufficient area on the site with slopes less than 20% to accommodate development and streets. The Planning Commission may authorize grading and structures on slopes exceeding 30% only if the Commission finds there is not sufficient area on the parcel with slopes less than 30% to accommodate a reasonable development, and measures have been incorporated into the development to minimize disturbance of the terrain (e.g. use of stem walls, split foundations).

D. Setbacks between structures and slopes. Proposed structures shall be set back from slopes as follows, based on the difference in the vertical elevation between adjoining parcels. The difference in vertical elevation shall be measured as shown in Figure 3-9. (See Figure 3-9, Slope Setbacks)

1. On adjacent parcels having a differ-ence in vertical elevation of three feet or more, the required side yard shall be measured from the toe or top of slope to a structure, which-ever is nearer.

2. On adjacent parcels having a difference in vertical elevation of six feet or more, the minimum distance between the toe or top of the slope, whichever is nearer, and a main structure shall be 15 feet. Greater setbacks may be required when elevation changes greater than six feet are proposed.

E. Height limits. The height of structures in a hillside area shall not exceed the maximum established by the applicable zoning district. Measurement of structure height shall be as provided in Section 18.30.090 (Height Measurement and Height Limit Exceptions). Lesser heights may be required where the structure may impair prominent views to or from hillside areas or prominent ridgelines.

F. Grading and drainage.

1. Grading shall be designed to:

a. Conserve natural topographic features and appearances by minimizing the amount of cut and fill and by means of landform grading to blend graded slopes and benches with the natural topography; and

b. Retain major natural topographic features (i.e., canyons, knolls, ridgelines, and prominent landmarks.)

2. Grading plans shall identify slopes that are to be landform graded. "Landform grading" means a contour grading method that creates artificial slopes with curves and varying slope ratios in the horizontal plane designed to simulate the appearance of the surrounding natural terrain. (See Figure 3-10, Landform Grading)

3. Lot pad grading for subdivisions shall be limited to the structure footprint, vehicle parking space and a yard area as shown on the approved grading plan. Lot pad grading shall be reviewed and approved as part of the subdivision process. Pads shall not exceed 5,000 square feet in total area. Smaller pad areas may be required.

4. Cut and fill slopes shall be designed and constructed to not exceed a vertical height of 10 feet, unless the review authority approves slopes of greater height with benching, terracing, and/or the use of retaining walls.

5. All graded areas shall be protected from wind and water erosion. Interim erosion control plans shall be required, certified by the project engineer, and reviewed and approved by the Town Engineer. Permanent erosion control measures in accordance with Best Management Practices of the "Project Guidelines for Erosion Control for the Truckee River Hydrologic Unit" as adopted by the Lahontan Regional Water Quality Control Board shall be required.

6. Slopes created by grading shall not exceed a ratio of 2:1 (vertical:horizontal), except where the Director determines that a greater slope is appropriate, based on a soils report and stabilization study.

18.36.050 - Design Criteria for Hillside Development

The following design criteria shall be implemented in the design and construction of projects on hillsides whenever applicable:

A. Preservation of topography. The natural contour of the site is an important characteristic of the site, and new buildings should try to minimize alterations to the perceived slope of the area. Site grading should be sensitive to existing land forms and topography so that the natural setting may be preserved to the greatest extent possible. Every effort should be made to minimize the limits of construction on the site, and all stockpiling of materials and equipment and equipment storage should occur within those limits. Abrupt grade changes on property lines should not be permitted. Grade changes within tree driplines should be avoided.

B. Terrain alteration. The project shall be designed to fit the terrain rather than altering the terrain to fit the project. Development patterns which form visually protruding horizontal bands or steeply cut slopes for roads or lots shall be avoided.

C. Street layout. Streets shall follow the natural contours of the terrain in order to minimize the need for grading. Cul-de-sacs and loop roads are encouraged where necessary to fit the natural topography subject to the approval of the Town Engineer and the Truckee Fire Protection District;

D. Site and structure design. Site design shall utilize varying structure and setbacks, heights, split-level foundations, and retaining walls to terrace structures with the direction of the slope;

E. Lot line locations. Lot lines shall be placed at the top of slope areas to help ensure that the slope will not be neglected by the up-hill owner; (See Figure 3-11, Lot Line Location)

F. Design and location of structures. Structures proposed on slopes shall be designed and located as follows.

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. Some techniques which may be considered include:

a. Split pads, stepped footings and grade separations to permit structure to step up the natural slope.

b. Detaching parts of a dwelling (e.g., a garage).

2. Excessive cantilevers should be avoided on downhill building elevations.

3. Structures should be placed partly underground or utilize below grade rooms to reduce effective bulk and to provide energy efficient and environmentally desirable spaces. However, the visible area of the building shall be minimized through a combined use of regrading and landscaping techniques.

4. Roofs on lower levels should be used as the deck open space of upper levels.

5. Architectural treatment shall be provided to all sides of the structure visible.

6. Exterior structural supports and undersides of floors and decks not enclosed by walls shall be permitted provided fire safety and aesthetic considerations have been adequately addressed.

7. Building materials and color schemes should blend with the natural landscape of earth tones and natural vegetative growth.

8. To the extent possible, the width of a building measured in the direction of the slope, shall be minimized in order to limit the amount of cutting and filling and to better "fit" the house to the natural terrain.

9. Structures should be placed to minimize disturbance of natural vegetation on slopes of 10 percent or greater.

G. Retaining walls. Large retaining walls in a uniform plane shall be avoided. Retaining walls over five feet in height shall be divided into elements and terraces with landscaping to screen them from view. Generally, no retaining wall should be higher than 10 feet. Where feasible, retaining walls should be constructed of the same materials as the primary buildings on the site. (See Figure 3-12, Retaining Wall Materials) (See Figure 3-13, Retaining Wall Design)

H. Open space preservation. Open space may be preserved by reducing the width of street improvements, reducing sidewalk widths, using common driveways and clustering units subject to the approval of the Town Engineer and Truckee Fire Protection District.

I. Slope restoration. Transitional slopes shall be replanted with self-sufficient trees, shrubs and ground cover that are compatible with existing surrounding vegetation in order to enhance the blending of manufactured and natural slopes. Cuts and fills shall have good surface drainage and shall be revegetated and terraced or controlled by retaining walls to protect against erosion and sedimentation. (See Figure 3-14, Slope Restoration)

J. Road alignment. The alignment of roads and driveways should follow the contours of the site. By meandering roads and driveways to follow land forms, it is possible to minimize cuts and fills, preserve natural drainage patterns, and produce roads that are easily negotiated. Roads should not be constructed perpendicular to contours.

K. Reduced street widths. On-street parking lanes may be omitted from streets when the result is a substantial decease in cutting and/or filling. Off-street parking areas shall be provided to yield a ratio of one additional space per dwelling unit.

L. Preservation of ridgelines. Prominent ridgelines shall be preserved. Structures located adjacent to prominent ridgelines should complement, rather than provide a stark contrast with, the natural landform(s). Structures shall not be closer to a prominent ridgeline than 100 feet measured horizontally on a topographic map. In no case, shall the roofline or any other portion of a structure extend above the line of sight between a ridgeline and any public right-of-way, whether the ridgeline is above or below the right-of-way. (See Figure 3-15, Development Does Not Preserve Ridgeline) (See Figure 3-16, Development Preserves Ridgeline)

18.36.060 - Criteria for Use Permit Approval

The Commission shall evaluate a Use Permit application for hillside development based on the following objectives, and the findings required for Use Permits by Chapter 18.76:

A. The preservation of natural topographic features and appearances by means of landform grading so as to blend constructed slopes into the natural topography;

B. The preservation of natural topographic features and appearances through restrictions on successive padding and terracing of building sites;

C. The retention of major natural topographic features - drainage courses, steep slopes, watershed areas, vernal pools, view corridors, and scenic vistas;

D. The preservation and enhancement of prominent landmark features - significant ridgelines, rock outcroppings, prominent trees and woodlands, and other areas of special natural beauty;

E. The use of varying setbacks, building heights, foundation designs and compatible building forms, materials, and colors which serve to blend buildings into the terrain;

F. The use of clustered sites and buildings on more gently sloping terrain so as to reduce grading alterations on steeper slopes;

G. The use of building designs, locations, and arrangements which serve to avoid a continuous intrusive skyline effect and which afford view privacy and protection;

H. The preservation and introduction of plant materials to protect slopes from soil erosion and slippage and minimize the visual effects of grading and construction of hillside areas; and

I. The use of street designs and improvements which serve to minimize grading alterations and harmonize with the natural contours and character of the hillsides.