Irvine Municipal Code Ch. 5-4 Hillside Overlay District

The purpose of this district is to provide regulations for the development of those areas in the City of Irvine and the sphere of influence which, due to their topography, require special consideration to assure that they are developed in a way that will substantially maintain their natural character and environmental and aesthetic values in accordance with the policies set forth in Section 5-4-2 below.

(Code 1976, § V.E-503.1; Ord. No. 92-3, 4-14-92; Ord. No. 94-7, § 3, 6-14-94)

The policies of the City of Irvine with regard to development in hillside areas are as follows:

A. To preserve the most visually significant slope banks and ridgelines in their natural state.

B. To minimize the effects of grading and ensure that the natural character of the hillside is retained.

C. To preserve visually significant rock outcroppings, native plant materials, natural hydrology, and areas of historical or visual significance.

D. To preserve views of significant visual features as viewed both from within the hillside community and outside the hillside community.

E. To encourage a variety of housing types, padding techniques, grading techniques, lot sizes, site design, density, arrangement, and spacing of homes and developments.

F. To encourage innovative architectural, landscaping, circulation and site design.

G. To discourage grading of large pads and excessive terracing.

H. To provide for safe circulation of vehicular and pedestrian traffic to and within the hillside areas and to provide access for emergency vehicles necessary to serve the hillside areas.

I. To provide safety against unstable slopes or slopes subject to erosion and deterioration in order to protect human lives and property.

J. To permit only those developments which are not detrimental to the public health, safety and welfare.

(Code 1976, § V.E-503.3; Ord. No. 92-3, 4-14-92; Ord. No. 94-7, § 3, 6-14-94)

The Planning Commission shall approve, conditionally approve or disapprove plans in accordance with the provisions of Section 5-4-2 of this chapter. In order to implement the policies of the City of Irvine for the development of hillside areas within the City and the sphere of influence (San Joaquin Hills and Lomas de Santiago Hills area), project plans for the development of property in this district shall be subject to review as follows:

A. Change of underlying land use category.

1. Submittal requirements. At the time that an application is filed for a zone change to change the underlying land use category, the applicant shall submit the following information and maps at a scale where one inch equals 200 feet or other appropriate scale.

a. A conceptual grading plan depicting the following:

(1) Planning area boundaries;

(2) Areas to be left undisturbed area (not graded);

(3) Areas which will not be developed;

(4) Areas of proposed cut and fill (in contrasting colors) clearly showing where cut and fill exceed depths established in the hillside development guidelines;

(5) Contour intervals of 10 feet for existing and ultimate grades.

b. A slope map depicting existing slope zones in percentage categories and contrasting colors as follows:

c. A conceptual drainage and flood control plan describing planned drainage improvements.

d. A conceptual landscape plan which addresses entryway treatment, streetscapes and other overall planning area landscape elements.

e. A preliminary geological and soils report prepared by a registered engineering geologist.

f. A natural features map identifying all slope banks, ridgelines, natural drainage courses, rock outcroppings, existing vegetation and other natural features determined to be worthy of consideration for preservation. Also depicted shall be landslides and other existing geologic hazards. Each feature depicted shall be noted for its visual (V) significance, environmental function (E), or both.

g. Photographic renderings, view analysis, three-dimensional models and other information if required by the Director of Community Development.

2. Findings.

a. Prior to making a recommendation for approval of change in land use category, conceptual grading plan, drainage plan, landscape plan or natural features map, the Planning Commission shall first find that:

(1) The proposed development concepts and plans are compatible with the natural topography of the site; and

(2) They are in conformance with the spirit and intent of the hillside development policies and guidelines.

b. Prior to final approval of the zone change by the City Council, the following shall be conceptually identified on maps at an appropriate scale for incorporation into the planning area zoning:

(1) All natural features determined to be significant for their visual or environmental function and which are to be preserved or further considered for preservation.

(2) All open space areas to be offered for dedication.

(3) All community collector roads and arterials and their proposed alignments.

(4) Development from which views to significant features are to be preserved.

(5) Conceptual grading plan.

(6) Conceptual landscape plan.

(7) Conceptual drainage and flood control plan.

B. Master Plan.

1. Submittal requirements. A Master Plan shall be submitted for approval in accordance with Chapter 2-17. The applicant shall submit the following additional information and maps at a scale where one inch equals 200 feet or other appropriate scale.

a. A conceptual grading plan, including information necessary to determine the proposed grading concepts, elevation of pads, and natural features to be preserved. The following specific information shall be depicted:

(1) Areas to be left natural.

(2) Areas of proposed cut and fill (in contrasting colors) clearly showing where cut and fill exceed depths established in the hillside development guidelines.

(3) Contour intervals of 10 feet for existing and ultimate grades.

b. A slope zone map for the area under consideration which depicts existing slope zones, in contrasting colors, in accordance with the adopted planning area slope zone map.

c. An updated conceptual drainage and flood control plan for the area under consideration.

d. A conceptual landscape plan which addresses the landscape treatment for the area under consideration.

e. Photographic renderings, view analysis, three-dimensional models and other information if required by the Director of Community Development.

2. Findings. Prior to final approval, the Planning Commission shall find that the proposed development plans are in conformance with the spirit and intent of the hillside development policies in Section 5-4-2 and the proposed concepts and plans are compatible with the natural topography of the site.

C. Tentative subdivision maps.

1. Prior to, or concurrent with, the submission of a tentative tract or parcel map within the Hillside District, the following shall be submitted for review and approval by the Planning Commission, in the number and at the scale specified by the Director of Community Development:

a. Any required conditional use permits for residential development.

b. Erosion control plans.

c. Landscape plans.

d. Grading plans.

e. Precise drainage and flood control plans.

f. Photographic renderings, view analysis, three-dimensional models, and other information if required by the Director of Community Development.

Note: Subject to approval of the Planning Commission, Items b through e may be submitted at a later time for approval by the Director of Community Development.

2. Findings. Prior to final approval, the Planning Commission shall find that the proposed development plans are in conformance with the spirit and intent of the hillside development guidelines and the proposed development concepts and plans are compatible with the natural topography of the site.

D. Grading and building permits. Prior to the issuance of grading or building permits, prints of the final grading plans, in the number and at the scale specified by the Director of Community Development, shall be submitted to and approved by the Director of Community Development. The Director of Community Development shall approve the final grading plans only if they are in substantial conformance with conceptual grading plans previously approved by the Planning Commission and City Council. In the absence of previous conceptual grading plan approval by the Planning Commission or City Council, the approval of the final grading plan shall be granted by the Planning Commission.

(Code 1976, § V.E-503.4; Ord. No. 92-3, 4-14-92; Ord. No. 94-7, § 3, 6-14-94)

These apply to all areas shown on Figure 5-4B and 5-4C. In order to implement the policies of the City of Irvine for the development of hillside areas in the San Joaquin Hills and Lomas de Santiago Hills, project plans for the development of property in these districts shall be subject to review as indicated in Section 5-4-3 and as follows:

A. Slope analysis procedures.

1. Submit, along with a concept plan, zone change or master tentative map, a contour map of the project area with the following information:

a. Delineate on the contour map:

(1) All project areas.

(2) All drainage courses, rock outcroppings and permanent open spaces.

b. Calculate the average existing slope for each project area.

Average Existing Slope: S = 100 × l × L/A

S = Average existing slope (%).

l = Contour intervals (feet).

L = Sum of length of contours feet excluding drainage courses, rock outcroppings and all permanent open space within the project area (feet).

A = Total square feet in a project area excluding drainage courses, rock outcroppings and all permanent open space within the project area (square feet).

c. Assign one of four slope zones to each project based on the average existing slope. (Show the corresponding slope zone for each project area based on table A below.)

B. Location and character of development. Table A shall serve as general guidelines for establishing slope zones to ensure that development will complement the overall character of the landform. In order to permit the extension of a logical design concept, the guidelines for one zone may be applied to limited portions of an adjacent zone.

1. Development is permitted in all slope zones, exclusive of preservation areas.

2. Major ridgelines are identified on Figure 5-4A and will be preserved as open space. The top of structures will be positioned below the top elevation of any adjoining major ridgeline. Ridgelines not identified as "major" may be developed as consistent with other applicable hillside development guidelines contained herein.

3. Development shall be permitted in identified seismic or geologic hazard areas (General Plan seismic element, Seismic Response Areas 4 and 5), natural springs, perched water tables, faults, fracture zones and where bedding planes project out of the slope subject to the City's review and acceptance of a detailed geologic or soils engineer's report which identifies mitigation measures required for safe development of the site.

4. Development shall be located to preserve and protect significant historical, archaeological and paleontological sites in accordance with the policies of the General Plan cultural resources element. The significance of historical, archaeological, and paleontological sites shall be determined through the environmental assessment process.

5. Upon annexation of the southern sphere of influence, the Hillside Overlay District zoning shall apply to those areas with slopes in excess of 10 percent.

C. Grading.

1. Revegetation of cut and fill slopes shall be required according to the guidelines in the landscaping section herein (Landscaping).

2. Within "transition zones," buffer areas separating preservation areas from areas of development, the following shall apply:

a. The overall slope, height and grade of any cut and fill slope shall be in character and scale with the natural terrain in the adjacent preservation area.

b. Where feasible, the toes and tops of all slopes in excess of 10 feet in vertical height and visible from public areas shall be rounded with curves in proportion to the total height of the slope.

c. Any dwelling unit shall be located a minimum of 10 feet from the toes and tops of all slopes which are over 10 feet in vertical height.

3. Manufactured slopes shall be contour graded or screened by landscaping in accordance with the following techniques:

a. The angle of graded slopes which are visible shall be gradually adjusted to the angle of adjoining natural terrain.

b. Graded slopes shall be vegetated and shall reflect the form of existing contours.

c. The toes and tops of visible graded slopes in excess of 10 feet in vertical height shall be screened by landscaping or rounded in proportion to the height of the slope where drainage and geotechnical stability permit such rounding.

d. The horizontal contours of graded slopes shall be screened by landscaping or curved in a continuous, undulating fashion.

4. Except for road and utility construction in accordance with approved plans and agricultural uses, grading will be prohibited until a tentative tract or parcel map has been approved for the area. Grading for borrow or disposal of earth outside of the tract boundary may be approved by the Planning Commission provided plans conform to an approved planning area level conceptual grading plan and residents in the area have been advised in advance.

5. Grading plans will include mitigation measures that reduce to acceptable safety levels underground water seepage which may occur because of increased irrigation or landform alteration.

6. Conceptual grading plans shall be submitted in accordance with the provisions of Section 5-4-3 of the existing Hillside Development Overlay District.

D. Landscaping.

1. Where feasible, all landscaped common areas shall use recycled water when permanent irrigation is required and the supply of recycled water supply is adequate.

2. All cut and fill slopes shall be vegetated. Landscape and irrigation plans shall be submitted for approval.

3. New landscape materials introduced as transition planting shall be used to integrate the manmade and natural environments, to screen and soften the visual impact of development and to provide privacy within existing adjacent development. Refer to the City's landscape manual and standard plans.

E. Drainage.

1. Interceptor ditches shall be established only where necessary above cut/fill slopes and the intercepted water conveyed to a stable channel or natural drainage with adequate capacity.

2. Road designs shall be such that water on roadways is prevented from flowing off the roadway in an uncontrolled fashion.

3. Natural drainageways shall be riprapped or otherwise stabilized below drainage and culvert discharge points for a distance sufficient to minimize channel erosion.

4. Runoff from areas of concentrated impervious cover (e.g., roofs, driveways, roads) shall be conveyed to a natural drainage or drainage structure with sufficient capacity to accept the discharge without undue erosion. The effects of new drainage patterns on existing systems shall be accounted for in the design of the project drainage plan.

5. Sediment catchment basins and other erosion/siltation control devices shall be constructed and maintained in accordance with an overall erosion control plan approved by the City.

6. The overall drainage system shall be completed and made operational at the earliest practical time during construction.

F. Views.

1. Homes will be oriented to allow view opportunities, although such views may be limited. Residential privacy should not be unreasonably sacrificed.

2. Any significant public vista areas and view corridors to preservation areas from arterial highways to be protected will be identified at the time of zone change in accordance with the provisions of Section 5-4-3 of the existing Hillside Development Overlay District. Public vista areas and view corridors within project areas are not required to be protected.

G. Roadways.

1. Variations in the City's established roadway standards shall be carefully considered for reduction in Slope Zones 2, 3, and 4 where safety and circulation considerations justify.

2. Sidewalks should only be required in Slope Zones 2, 3, and 4 only when other means of safe and convenient pedestrian circulation are not available, and then only in accordance with a carefully conceived total pedestrian circulation plan.

3. Grading for local and collector roadways shall comply with Subsection 3 of "Grading" herein.

4. Those portions of Bake Parkway and Sand Canyon Avenue which are located within or abut preservation areas shall be contour graded and vegetated in accordance with the following techniques where feasible:

a. The angle of graded slopes shall be gradually adjusted to the angle of adjoining natural terrain.

b. Graded slopes shall be vegetated with drought-resistant plant species.

c. Graded slopes shall reflect the form of existing contours. Horizontal contours shall be curved in a continuous, undulating fashion.

d. The toes and tops of graded slopes in excess of 10 feet in vertical height shall be rounded in proportion to the height of the slope where permitted by drainage and geotechnical stability.

H. Fire protection.

1. Hillside development within "high" or "extreme" fire hazard zones, as determined through the environmental review process, shall be designed to reduce fire hazards in accordance with the requirements of the Orange County Fire Marshal.

I. Open space/development boundary.

1. Access to special, endangered, rare or fragile plant and animal habitats shall be limited, with public access carefully managed to prevent disruption of the area's natural values.

2. Public access to public resources shall be provided, where appropriate, in accordance with the requirements of the subdivision ordinance (Title 5, Division 5 of the Irvine Municipal Code). Conflicts between public access to public resources and the need for security and privacy of residents will be minimized.

3. At the boundary between development and preservation areas ("transition zones") provisions will be made for fuel modification zones in accordance with the fire protection guidelines. Maintenance of these fuel modification zones shall be the responsibility of the respective maintenance district, community association or other appropriate agency. Areas in fuel modification zones subject to public access or use should be the responsibility of an appropriate public agency.

(Code 1976, § V.E-503.5; Ord. No. 92-3, 4-14-92; Ord. No. 94-7, § 3, 6-14-94; Ord. No. 01-01, § 5, 1-23-01)

Editor's note— Ord. No. 01-01, § 5, adopted January 23, 2001, amended the Code by repealing former § 5-4-5 in its entirety. Former § 5-4-5 pertained to review procedures for Lomas de Santiago Hills, and derived from the Code of 1976, § V.E-503.6; Ord. No. 92-3, adopted April 14, 1992; and Ord. No. 94-7, adopted June 14, 1994.

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