19.03.160 Geologically Hazardous Areas:
A. General. Geologically hazardous areas are areas that are susceptible to erosion, sliding, earthquake, or other geological events and pose a threat to the public health, safety, and welfare. The siting of residential, commercial, or industrial development within these areas is a potential hazard. These areas include steep slopes, landslide-erosion hazard areas, and seismic hazard areas
B. Development Standards.
1. Applications for development activity within designated hillsides of fifteen percent (15%) slope and greater shall be accompanied by a geotechnical report prepared by a geologist or geotechnical engineer licensed as a Civil Engineer with the State of Washington.
2. Applications for development activity within designated landslide or erosion hazard areas shall be accompanied by a geotechnical report prepared by a geologist or geotechnical engineer licensed as a Civil Engineer with the State of Washington.
3. Applications for development activity proposed within designated seismic hazard areas shall be accompanied by a geotechnical report prepared by a geologist or geotechnical engineer licensed as a Civil Engineer with the State of Washington.
C. Geotechnical Report Requirements. A geotechnical report required under this section shall include, at a minimum, the following information:
1. Topographic maps at a minimum scale of 1:2400 (1 inch = 200 feet). Slope ranges shall be clearly delineated in increments of 15-25%, 25-40%, and 40% or greater.
2. Site history, including description of prior grading and clearing, soil instability, or slope failure.
If a valid geotechnical report has been prepared within the previous two (2) years for a specific site and the proposed land-use development and site conditions have not changed, the report may be utilized without the requirement for a new geotechnical report.
D. Geotechnical Report Assessment. If it is satisfactorily demonstrated within the geotechnical report that hillsides of fifteen percent (15%) slope or greater, landslide and erosion hazard areas, and or seismic hazard areas do not exist on the site, the requirements of this section shall be waived. If it is determined within the geotechnical report that a potential threat to public health, safety, and welfare exists from development of the site, then the applicant shall prepare a geologic hazard plan.
E. Geologic Hazard Plan. The geologic hazard plan shall include discussion of the potential impacts from the proposed development and specific measures or alternatives designed to mitigate any potential adverse impacts of the applicant’s proposal on and off-site. The Planning Commission shall review the geologic hazard plan and make a determination if the development proposal warrants approval, conditional approval, or denial. The Planning Commission shall consider the following areas in their determination:
1. Percentage of site proposed to be disturbed by development
2. Location of development on site
3. Design proposed for the development
4. Construction type proposed for the development (Ord. 2134, 11/11/03; Ord. 1532, 1992)