Rules for building on steep slopes

Purpose.To insure public safety from earth slides and slips.To minimize erosion and attendant siltation of downstream waters.To insure safety from downstream flooding due to altered runoff characteristics.To protect ecologic functions such as ground water recharge, wildlife habitats, and vegetative communities.Lands Included. All land areas in excess of 20% slope (one foot of rise or fall in five feet measured horizontally).Requirement for Development Within the Slope District. No Zoning, Building, or Use Permit shall be issued, nor shall any use requiring the development, grading, or alteration of any portion of the Slope District be permitted, unless the applicant establishes conformity with the requirements of this Section.Applications for all subdivision development, land alteration or clearing, other than one single family dwelling unit on an existing parcel shall include specific development plans indicating:The location, size, nature, and intended use of all buildings, roads, walkways and other impervious surfaces.Limits and extent of all clearing and grading operations; grading plans showing existing and revised contour lines; cross sections showing cuts and fills anticipated; angles of slopes and structural appliances such as retaining walls and cribbing.Sizes and locations of existing and proposed surface and subsurface drainage with expected quantities and velocities and treatment of outfalls.Provisions for siltation and erosion control during construction and plans and schedules for revegetation of all cleared or graded areas not covered by impervious surfaces.When required by the Department of Public Works, a soils and geology report by a soils engineer defining existing soil and geologic stability and other pertinent characteristics and certifying the stability of the proposed development.When required by the Planning Director, an environmental impact study indicating critical areas of concern and the effects of the proposed development on physical, biologic, ecologic and environmental forms and systems, such as downstream water quality, flood plains, wildlife, vegetation, and marine ecologies, visual and historic amenities, and air or ground water pollution.All graded areas not covered by a building or other impervious surfaces and all fill slopes steeper than one foot of rise in three feet horizontally shall be revegetated within six months of the commencement of grading unless areas other than fill slopes must be left bare because of other construction activities. The Department of Public Works may require revegetation of portions of the graded area which in its opinion are not necessary to in-progress construction, or where significant construction activity has been suspended for over 60 days. Grading operations which extend over one year shall require a time extension from the Department of Public Works. All bare areas where excessive erosion and dust problems may occur shall be revegetated prior to final inspection.Modification of Requirements. The requirements of this Article shall not apply where the applicant demonstrates to the satisfaction of the Department of Public Works that the area in question should not have been included in the Slope District under the criteria established in Subsection (b).