The standards of this division are intended to:

A.

Preserve the City's scenic resources by encouraging retention and/or protection of the City's natural topographic features and vegetation such as hillside ridgelines, steep slopes, and other hillsides that have aesthetic value to the City of Colton and contribute to the community's sense of identity;

B.

Acknowledge that as the slope of a development site increases so does the potential for environmental degradation including slope failure, increased erosion, sedimentation and Stormwater run-off; and

C.

Encourage grading practices that are appropriate in hillside areas such as implementation of land form grading; and

D.

Encourage structures on hillside parcels to be designed with scale, massing, architectural design and detailing appropriate to maintain hillsides in a natural, open character ensuring that buildings and structures blend with the natural environment through their shape, materials, and colors.

(Ord. No. O-03-15, § 14, 3-3-2015)

The City's hillsides and ridgelines are a unique resource and pose additional design considerations. The Hillside Standards contained herein apply to all uses and structures within areas having a natural slope percentage of 15 percent or greater over an area being graded and requiring a grading permit. This includes all subdivisions, grading, or new development projects with slopes that are calculated at 15 percent or greater over the area being graded and require a grading permit unless otherwise exempted by this code.

If requested by City staff, proof of slope shall be submitted in order to show that the slope is less than 15 percent; the slope must be calculated by a licensed engineer, surveyor or architect in the State of California.

Existing Adopted Specific Plans with Hillside Standards shall apply in lieu of this section.

(Ord. No. O-11-20, § 8, 10-20-2020)

Development that is subject to this section Shall require a Pre-Application, followed by Architectural and Site Plan Approval as a public hearing item by the Planning Commission subject to this title. The application Shall include:

A.

Basic Application Contents. All information and materials required by Section 18.53.030 (Application Preparation and Filing), and all additional materials required by the application contents handout provided by the Development Services Department for hillside development; and

B.

Grading Plans. Existing conditions and Proposed Grading Plans are required in advance of subdivision map submission for review by the Development Services Department and City Engineer.

C.

Geotechnical Report. A preliminary geotechnical report that identifies and proposes mitigation measures for any soils or geological problems that may affect site stability or structural integrity. Depending upon the site characteristics and project design, a final geotechnical report May also be required as part of a subsequent Building Permit application.

D.

Building Footprints on Site Plan. Each proposed lot shall provide building footprint of the future home or structure as part of the Architectural and Site Plan Review approved by the Planning Commission.

E.

Electronic Plans Simulations. Each proposal is required to submit the proposed site plan with proposed building pad locations for use in visual simulations for review of the proposed subdivision by the City and Planning Commission.

F.

Constraints Analysis. For properties that have sensitive environmental resources including endangered plants and animals drainage feature, or a wildlife corridor designated by the City, a qualified professional approved by the Director Shall prepare a site constraints analysis. The report Shall include proposed mitigation measures to effectively protect important identified biological features.

(Ord. No. O-03-15, § 14, 3-3-2015; Ord. No. O-11-20, § 8, 10-20-2020)

Hillside developments Shall comply with the following standards.

Notes:

1. Side setbacks May be reduced to five feet minimum with justification of hardship related to hillside protection or other hillside feature protection, subject to Planning Commission review and approval through Architectural and Site Plan Review.

2. New structures or additions are prohibited within fifty vertical feet of a ridgeline unless this restriction precludes development of the property. An exception May be granted if the review authority finds the following:

 a. There are no site development alternatives including clustering that avoid ridgeline development;

 b. The density has been reduced to the minimum standards consistent with the General Plan density range;

 c. No new subdivision of parcels is created that will result in ridgeline development; and

 d. The proposed development will not have significant adverse visual impacts due to modifications in structural design including height, bulk, size, foundation, siting, and landscaping that avoid or minimize the visual impacts of the development.

A.

Setbacks Between Structures and Toes/Tops of Slopes. On adjacent lots having a difference in vertical elevation of three feet or more, the required side yard Shall be measured from the nearest toe or top of slope to the Structure, whichever is closer. See Figure 1.

Figure 1.
Side Setback Measurement

B.

Height Limitations. The maximum height for Structures with a roof pitch of 3:12 or greater Shall be twenty-eight feet. If a roof pitch is less than 3:12, the maximum height Shall be twenty-four feet.

1.

Siting Restrictions/Protection of Ridgelines. Structures Shall not be placed so that they appear silhouetted against the sky when viewed from a public street, except where the review authority determines that the only feasible building site cannot comply with this standard. See Figure 2 below.

Figure 2.
Silhouetted Structures

2.

Placement Below Ridgeline. Except as provided by Subsection C.3, Structures Shall be located so that a vertical separation of at least fifty feet is provided between the top of the Structure and the top of the ridge or knoll to maintain the natural appearance of the ridge. Grading should also be avoided within fifty vertical feet of the top of a ridge or knoll. Placement of Structures should also take advantage of existing vegetation for screening, and should include the installation of additional native plant materials to augment existing vegetation, where appropriate. See Figure 3 below.

Figure 3.
Placement below ridgeline

3.

Height Limit Above Ridgeline. Where the review authority determines that a parcel contains no feasible building site other than where a structure will extend above the ridgeline, proposed structures Shall not exceed a height of sixteen feet above the highest point on the ridgeline or hilltop within one hundred feet of the proposed structure.

4.

Height of Lowest Floor Level. The vertical distance between the lowest point where the foundation meets grade and the lowest floor line of the structure Shall not exceed six feet.

5.

Downhill Building Walls. No single building wall on the downhill side of a house Shall exceed fifteen feet in height above grade. Additional building height on a downhill side May be allowed in fifteen-foot increments, where each increment is stepped-back from the lower wall a minimum of ten feet. See Figure 4 below.

Figure 4.
Downhill Building Walls

C.

Decks. No portion of the walking surface of a deck with visible underpinnings Shall exceed a height of six feet above grade. Decks should be integrated into the architecture of the house, not appearing as an "add-on" to the primary building mass.

Building Support Structures. Support Structures (for example, columns, pilings, etc.) below the lowest floor on the downhill side of a house, should be enclosed unless visible structural members are an integral feature of the architectural design. Support Structure wall surfaces Shall not exceed six feet in height—Figure 5.

Figure 5.
Design Sensitive to Terrain

Note— This diagram is intended to provide an example of building form, and is not intended to show a preferred architectural style.

D.

Driveways. The ramp to any garage or carport Shall not have a grade steeper than five percent within twenty feet of the garage or carport entry. The finished grade of driveways Shall not exceed an average of fifteen percent.

E.

Natural State. A minimum of twenty-five percent of the lot area plus the percentage figure of the average slope must be remediated to its Natural State in terms of slope and vegetation, except where fire modification measures are required.

F.

Grading. Grading plans Shall be prepared in compliance with the Municipal Code, and the General Plan, which prohibits grading on slopes over thirty percent. Grading Shall utilize landform grading techniques provided in Section [18.41.030 G]. See Figure 6: Appropriate Grading.

Grading in hillside areas should be the minimum necessary to be consistent with the other standards contained within the City's Municipal Code and General Plan Policies. Grading should be limited to that which is necessary for the primary use of each lot. Excessive grading outside of the building footprint and driveway area is discouraged. If necessary, all land form grading practices should be followed by the engineer of record as reviewed and approved by the City Public Works Department.

Figure 6.
Appropriate Grading

G.

Grading and Drainage Standards

1.

Grading Plans. Grading plans will be designed and prepared by a registered civil engineer in accordance with compliance with all Colton Municipal Code requirements, other applicable codes, instituting best engineering/planning practices and restrictions determined by detailed studies of the geological, hydrological and soils conditions of the site.

2.

Geotechnical Studies. In order to address the many potential unknown geological constraints of a hillside, areas such as potential unstable and steep slopes, possibly poorly compacted and partially compacted soils in low lying areas, and faults, geotechnical investigation, by an engineering geologist and a soils engineer—registered by the State of California, Shall be conducted as part of the Architectural and Site Plan Review conducted by the Planning Division and approved by the Planning Commission.

3.

Natural Features. Significant natural landmarks and other outstanding hillside features Shall be maintained in the Natural State as determined by the City's Development Services Director.

4.

Landform Grading. All natural slopes greater than five feet in height that require grading, landform grading (contour grading) Shall be used to simulate the appearance of the natural terrain. (See Figure 7.)

Figure 7.
Landform Grading

5.

Remedial Grading. Notwithstanding the limitations of this subsection, the Development Services Director May permit remedial grading pursuant to an Administrative Architectural and Site Plan Review. For the purposes of this Section, remedial grading is defined as grading necessary to mitigate an environmental hazard as recommended by a geotechnical report approved by City engineering staff. No such remedial grading will be allowed when it could be avoided by changing the position or location of the proposed development. Remedial grading that would result in substantial landform alteration Shall not be permitted where project alternatives, including but not limited to, deepened foundations, caissons, soldier piles could be utilized to provide equivalent geologic stability. Remedial grading Shall not be used to materially increase the buildable area of a project site.

6.

Slope Repairs. When the gradient of the natural slope exceeds twenty percent, five-feet horizontal and one-feet vertical (5:1), slope benches and terraces must be used when fill is used to repair even a small portion of a slope.

7.

Grading on Slopes Greater than Twenty-Five Percent Grade. Grading on naturally occurring slopes of twenty-five percent grade or more that are greater than twenty-five feet in height Shall not occur unless grading is for access and/or remedial purposes, and specifically approval by the City of Colton Architectural and Site Plan Review after geotechnical studies have been conducted by a soils engineer and an engineering geologist registered by the State of California. A detailed plan for slope stabilization Shall be submitted and approved prior to the issuance of any grading permits.

8.

Maximum Slope Angle for Manufactured Slopes. No manufactured slope Shall have a slope angle steeper than two-feet horizontal to one-feet vertical (2:1). Shallower slope angles May be required if detailed soils and geological investigations indicate that they are necessary.

9.

Preserving Existing Significant Riparian Habitats. Major natural drainage channels containing significant perennial vegetation that may constitute wildlife habitat should remain in their Natural State.

10.

Maintenance. All drainage, open space/landscaped buffer areas, detention ponds and sediment basins must be continuously maintained on a monthly basis either by homeowners association or property owner or existing maintenance assessment district.

11.

Street Layout. Any new streets should follow the natural contours of the terrain to minimize the need for grading. Street width are subject to design review and should be narrow in width preserving hillside and providing adequate safe access subject Design Review process. Cul-de-sacs are prohibited and loop roads are encouraged where necessary to fit the natural topography, all subject to the approval of the City Engineer, Development Services Director and Fire Chief.

12.

Grading for Roadways. Where placement of roads are near ridges or on slopes is proposed, acceptable roadway placements Shall include a split roadway section to accommodate grade, knob removal to accommodate views from the road, and the rounding of cut slopes to enhance appearance. See Figure 8.

Figure 8.
Grading for Roadways on Hillsides

Cut and Knob Removal

Split Roadway is Preferred

13.

When the established alignment of a road does not conform to the natural contours of slopes, excessively long stretches of manufactured straight embankments Shall not be permitted. Instead use undulated slope embankments as shown in the Figure 9 below:

Figure 9.
Undulated Slope Embankments

14.

View Protection. New construction should not block views from other properties.

a.

Where feasible, new structures and tall landscaping should not be placed directly in the view of the primary living areas on a neighboring parcel.

b.

New structures should be placed on the lower areas of a hillside site.

c.

Mechanical equipment May be placed on rooftops or below a deck only if the equipment is not visible from off the site, except for unobtrusive solar collectors that are compatible with the roof line and architecturally integrated with the structure. See Figure 12 below.

Figure 12.
View Protection

H.

Design Retaining Walls to Blend into their Surroundings. Large retaining walls in a uniform plane Shall be avoided. Retaining walls Shall be divided into terraces with variations in plane and include landscaping to break up the length of walls and to screen them from view. No retaining wall Shall be higher than six feet, except as specified in subsection 2., below, and should incorporate a three-foot recessed offset feature every thirty feet, or other methods of articulation. Retaining walls more than three feet high that are visible from off the site should be screened with landscaping.

1.

Minimize length of solid fences, landscape walls, and retaining walls on hillsides. Walls should not exceed 50 feet in length.

2.

Minimize fence and wall heights. An eight foot wall may be acceptable if the materials are aesthetically pleasing (for example, stone), but a six foot height limit is more appropriate for materials such as stucco and concrete block.

3.

Long, continuous walls may be acceptable if they undulate, are broken up by buttresses or pilasters, and are of appropriate natural materials such as stone or adobe. Plaster walls may be acceptable at the Planning Commission discretion.

Undulating Wall

Maximum Wall Length

Buttress Wall

4.

Use horizontal lines and proportions to reduce perception of height and bulk.

5.

Follow topography with fence and wall design.

6.

Use earth tone colors that tend to blend with the surrounding natural colors of the hillsides and minimize visual effects. Avoid use of colors contrasting with the surrounding natural terrain such as bright white walls or large areas of bright nonnative flowers.

7.

Use stone or other native, natural materials, where feasible.

8.

Integrate vegetation and landscaping with fence and wall design.

9.

Avoid locating retaining walls near existing walls.

10.

Retaining walls with fill behind them can be particularly visually disruptive.

Pilaster Wall

Example of quality wall design and drought-resistant landscaping

11.

Stepped or terraced retaining walls, with planting in between, may be an acceptable alternative to tall retaining walls.

12.

The minimum distance between two terraced retaining walls should be at least the average height of the two walls

A stepped terraced design avoids creating a tall retaining wall and landscaping help obscure the wall

Wall exceeds human scale—Not This

This—Landscaped stepped retaining walls contribute to human scale

13.

The following are maximum heights for retaining wall systems of a cut slope:

•

Eight feet maximum exposure for individual retaining walls.

•

Sixteen feet maximum combined exposed retaining wall faces.

(Ord. No. O-03-15, § 14, 3-3-2015; Ord. No. O-11-20, § 8, 10-20-2020)