Note: Prior ordinance history; Ord. 342-90.
The purpose and intent of this district is to:
A. 
Ensure that development in the Hillside area of the City occurs in a manner that is consistent with applicable policies of the open space, conservation, and seismic safety and safety elements of the general plan, and that development design responds to the topographic characteristics of each site;
B. 
Provide a mechanism for implementation of the City's Hillside area policies and ensure that future development preserves the scenic integrity of visible ridges and hillsides;
C. 
Ensure that the density of development on Hillside area lands is consistent with the capacity of the land to sustain it without undue environmental consequences, and is consistent with the level of services which reasonably can be provided by the City.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
The Hillside area consists of all portions of Union City north and east of Mission Boulevard, including any lands that may be annexed to that area in the future, regardless of slope or other characteristics.
(Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
The district and the specific regulations established by this chapter apply in all of the City's Hillside area. These regulations may be applied in combination with any one of the residential districts established by Chapter 18.32, which district shall be the base zoning district. When so combined, all regulations in this title prescribed for the base zoning district shall apply, and shall be augmented by the specific regulations prescribed in this chapter. In cases of conflict, the provisions of this chapter shall take precedence.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
The use provisions of the base zoning district notwithstanding, approval and authorization for any proposed development in the combining district shall be subject to the issuance of a conditional use permit pursuant to the provisions of Chapter 18.56.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
Development Density Limitations. For any proposed development, the maximum number of dwelling units that may be considered for development approval on the site shall be determined on the following basis:
A. 
For portions of the site with an existing average slope of 10% or less, full credit may be claimed for the maximum number of units that would be allowed under the base zoning district.
B. 
For portions of the site with an existing average slope exceeding 10%, credit may be claimed based on a proportion of the maximum number of units that would be allowed under the base zoning district in accord with the following table:
Slope Range (percent)
Proportion of Maximum Number of Units
10.1 – 15
0.50
15.1 – 20
0.25
20.1 – 30
0.10
30.1 – 40
0.05
Over 40
0.00
C. 
For purposes of the calculations, the maximum number of units allowed for each of the base residential districts is as follows:
Base District
Maximum Units (per gross acre)
RS - 10,000
3.5
RS - 8,000
4.5
RS - 7,000
5.0
RS - 6,000
6.0
RS - 4,500
8.0
RM - 2,500
14.0
RM - 1,500
23.0
D. 
To support the calculations, a slope analysis showing the boundaries of each existing slope range prepared on a topographic map of the site, at a scale of not less than one inch equals 100 feet, shall be submitted. A tabulation of the land area within each slope category, and a description of the method used in determining and measuring the slope areas shall accompany the map. In all cases, slopes shall be measured perpendicular to contour lines. In reviewing an application, the City shall ensure that slopes are calculated for individual areas that have similar slope characteristics. The submitted topographic map and tabulation of land area shall meet the approval of the City, which may retain an independent engineering specialist to review the submitted documents. The costs for such independent review shall be borne by the project applicant.
The total number of units derived from the calculations shall be considered only as a measure of the maximum density of development that may be proposed for the site, and does not commit the City to approval of any specific number of units. Final approval shall be based on design and engineering solutions for all other constraints that may affect the site, including access, geotechnical problems, slope stability, drainage, visual sensitivity and grading impacts as well as on-slope considerations.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1996; Ord. 670-06 § 3, 2006)
Only limited development or residential subdivision may occur in areas with existing slopes over 25%. In areas with slopes ranging from 25% to 40%, for which development credit is given as per Section 18.96.040(B), the allowed development density shall either be transferred to an area of a site with a slope of 25% or less, or developed under the slope density limitations in Section 18.96.040 with a base designation of RS-10,000. The transferred density shall in no case be allowed to increase the total allowed density above the maximum residential units specified for the base district in Section 18.96.040(C).
(Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
All applications for development approval under the provisions of this chapter shall be accompanied by a comprehensive geologic and soil investigation report prepared by qualified engineering specialists in the field, and meeting all City and State requirements for such reports. The report shall provide complete and detailed information on all geotechnical conditions known or suspected to be present in the area, and particularly shall contain detailed mapping of all faults, fault zones and landslides. Engineering solutions and/or other types of mitigation recommendations shall be provided on all soil, foundation, public utilities or seismic problems, including grading recommendations and erosion and sedimentation control measures, responding to the particular development proposal under review. The proposed solutions must meet the approval of the City, which may retain an independent engineering specialist to review the proposal. The costs for such independent review shall be borne by the project applicant.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
A. 
All applications for development approval under the provisions of this chapter shall be accompanied by a preliminary grading and drainage plan prepared on a topographic map of the site at a scale of not less than one inch equals 100 feet. Such plan shall show existing and proposed contours, including the top and toe of each cut and fill slope, with a contour interval not greater than five feet; provided, that a 10 foot interval may be shown on slopes not proposed to be graded. Proposed provisions for drainage, including slope stabilizing and erosion and sedimentation control measures shall be shown.
B. 
The grading and drainage plan shall include a tabulation of proposed cut and fill quantities and the proposal for disposition of any excess excavated material where the quantities are not in balance. Additional information, such as hydraulic calculations and cross-sections of proposed cut and fill slopes, may be required as determined to be needed by the City Engineer.
C. 
The preliminary grading and drainage plan shall be processed concurrently with the development approval by the Planning Commission and City Council.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
Grading shall be minimized in all areas with slopes above 10% by properly contouring areas where grading occurs. In assessing the appropriateness of grading, the City shall use the following guidelines:
A. 
Site grading should generally be limited to areas within the building footprint, under access roads and driveways, and where necessary due to unusual site conditions such as landslides.
B. 
Buildings and roads should generally follow contours. On sloping sites, buildings should have multiple levels, and be dug into and stepping down the hill.
C. 
Where grading occurs, new slopes should be configured to retain the natural character of the site. New contour lines should be rounded to mimic natural contours. Graded slopes should undulate and should not result in flat planes.
D. 
No artificial slope shall exceed the naturally occurring slopes in its immediate vicinity or a slope of 3:1, whichever is greater.
E. 
Graded areas shall be feathered so that there are no abrupt transitions between flat areas and graded slopes, or between graded and ungraded areas.
F. 
Graded slopes shall be revegetated with native species found in similar natural areas of the Hillside area.
(Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
The use permit and site development review procedures prescribed in Chapters 18.56 and 18.76 shall apply to all applications for development within this district, except where administrative site development review procedures apply as outlined in section 18.72.030. In its review, the Planning Commission shall particularly consider the following aspects of the proposed development:
A. 
Adequacy of Access. The proposed development should allow for adequate access in consideration of overall trip generation and hazards such as ground rupture from earthquake faults and wildfire. Typical road grades should be no more than 15% for collectors and ten percent for major roads. Maximum road grade should be 18%, except that roads may have grades of 20% over no more than 150 feet if they are paved with concrete.
B. 
Proposed Siting of Buildings in Relation to the Topographic Characteristics of the Site. The proposed development should avoid and maintain major topographic features of the site such as ridgelines and knolls in their natural states.
C. 
Proposed Overall Development Design in Terms of Response to the Visual Sensitivity of the Site. Major visual features of the site such as specimen trees and rock outcroppings should be maintained, and incorporated into the development proposal where appropriate. Development rights should be transferred from areas with these features to other portions of the site.
D. 
Relationship Between Proposed Architectural Treatment, Site Characteristics and Visual Sensitivity of the Area. Structures and site improvements should be designed to blend with and take advantage of the topography and visual resources of the site.
In addition to the information and exhibits required by the provisions of Sections 18.56.030 and 18.76.030, the Director may require that a visual analysis prepared by a qualified professional in the field and/or a scale model of the proposed development be submitted for Planning Commission review.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)
A. 
Within a proposed development, areas that are unbuildable because of steep slope or geotechnical hazards that cannot be mitigated shall be retained as open space.
B. 
Dedication to a public agency of development rights or scenic easements for undeveloped open space areas shall be required, and development approval shall be conditioned upon provisions satisfactory to the City Attorney which require permanent management and maintenance of such areas.
(Ord. 55.221-80 § 2, 1980; Ord. 454-95 § 2, 1995; Ord. 670-06 § 3, 2006)