The Hillside Overlay Zone covers the mountainous and other areas in the City of environmental concern. Because of topography, slope, soil conditions and other natural features, the area is considered to be environmentally fragile, and all developed activity occurring in the area should be carried out in a manner consistent with these natural limitations. It is hereby declared that the purpose and intent in establishing the Hillside Overlay Zone is to:
(1) 
Protect and conserve the soils, natural vegetation, and drainage ways and other natural resources within the area.
(2) 
Avoid the establishment of hazard from flood, fire, mud slide, and other dangers.
(3) 
Preserve the aesthetic appearance of the landscape and prevent excessive degradation of the environment.
(4) 
Permit certain types of development to take place under such conditions as will result in the substantial preservation of the natural features within the zone.
(5) 
Secure economy in governmental expenditures.
Permitted uses within the Hillside Overlay Zone shall include all uses permitted within the underlying zone subject to compliance with all requirements for development in hillside areas as set forth in this Article or elsewhere in this Code or in specifications and regulations adopted pursuant hereto.
All uses of land in the Hillside Overlay Zone shall conform to the following criteria:
(1) 
All land surface having a slope of twenty-five percent (25%) or greater shall remain in its natural state and shall not be graded or otherwise disturbed, except that the natural vegetation may be supplemented by other plants naturally occurring in the area; provided, however, roads may be constructed on slopes exceeding twenty-five percent (25%) if the following requirements are met:
(a) 
The road has been approved and is either an existing City street or detailed plans showing the precise location and engineering detail have been submitted and approved by the Land Use Authority.
(b) 
The Land Use Authority has determined that the proposed alignment is necessary for the proper development of the area and that there is no feasible alternate alignment which complies with the slope requirement.
(c) 
The plan provides adequate measures to ensure that all cut and fill slopes will be stabilized, that erosion hazards will be eliminated, that surface vegetation will be restored, and that other environmental hazards will be adequately handled.
(2) 
Each dwelling site shall contain a buildable area of not less than four thousand (4,000) square feet.
(3) 
No cut or fill slope that shall be created as a part of the construction of any roadway, dwelling, or other structure shall exceed the critical angle of repose, except by special permission of the City Council after recommendation of the Planning Commission. Such special permission shall not be given until the developer shows that he has adopted all practical measures to reduce the slopes to less than the critical angle of repose by selecting an alternate location, or by planting the slopes with natural vegetation, or by undertaking other action which will have the effect of preventing the soil from moving under the force of gravity until vegetation becomes established.
(4) 
All development shall provide to the satisfaction of the Land Use Authority for the disposal of surface water originating as a result of any modification in the environment. Provision shall also be made to the satisfaction of the Planning Commission for the accommodation of all storm water runoff arising on or above the site so as to prevent flooding or erosion.
(5) 
If it determines it to be necessary in order to adequately evaluate any proposed development in the Hillside Overlay Zone, the Land Use Authority may require an environmental impact statement containing the information specified in Section 11-6-128 and a geologic report containing the information specified in Section 11-6-129.
(6) 
No grading, filling, or excavation of any kind shall be commenced without first obtaining a grading permit as required by Title 10, Chapter 6. In issuing any such permit, the Building Official may, as a condition of the permit, require the person doing the grading, filling, or excavation to do such work in the manner specified by the permit in order to:
(a) 
Encourage only minimal grading which relates to the natural contour of the land and which will round off, in a natural manner, sharp angles at the top and ends of cuts and fill slopes;
(b) 
Retain trees and other vegetation which stabilize steep hillsides, retain moisture, prevent erosion, enhance the natural scenic view, and, where necessary, install additional landscaping to enhance the scenic and safety qualities of the area;
(c) 
Provide for immediate planting wherever appropriate to maintain necessary cut and fill slopes, to stabilize such areas with plant roots, to conceal raw soil from view, and to minimize erosion;
(d) 
Preserve natural drainage channels;
(e) 
Encourage retention of natural landmarks and prominent natural features, wildlife habitat, and open space;
(f) 
Preserve and enhance the visual and environmental quality of the area through the use of natural vegetation and prohibition of excessive excavation and terracing;
(g) 
Protect the public from natural hazards of runoff water and erosion by requiring drainage facilities.
(7) 
As a means of harmonizing development within the project with existing and planned development within the surrounding area, the Land Use Authority may, as a condition of its approval, specify or may require changes in the density, minimum and maximum height of buildings and structures, and type and style of architecture, the character and nature of landscaping, the pattern of circulation, the location and siting of buildings, fences, walls, utilities, lighting and sprinkling facilities, and other structures, as well as the nature and extent of drainage facilities.
(8) 
No dwelling or other structure used for human habitation shall be constructed on fill material, unless such material shall have been compacted as directed by the City Engineer. All fill in the Hillside Overlay Zone shall be compacted to at least ninety-five percent (95%) of American Association of State Highway Transportation Officials T180 density for those areas intended as structural foundations, including roadways.
(Ord. No. 20-2025 § 1, 10/21/2025)