Ordinance 2909-06 - Laserfiche WebLink

ii. Very high/severe erosion hazard areas include slopes of >40% in Qva and Qal geologic units. b. Those areas defined as medium risk of erosion in the Dames and Moore Methodology for the Inventory, Classification and Designation of Geologically Hazardous Areas City of Everett, Washington: July 1, 1991 when they contain debris and mud flows, gullying or rilling, immature vegetation, or no vegetation: i. slopes of 25-40% in other (not Qva or Qal) geologic units 4. Other areas which the city has reason to believe are geologically hazardous. B. Protective Requirements. 1. Geotechnical assessment requirements. Development proposals on or within 200 feet of any area designated as or which, based on site specific field investigation, the city has reason to believe are geologically hazardous areas shall submit a geological assessment as required by subsection F [37.080(F)]. 2. The setback buffer requirement shall be based upon information contained in a geological assessment, and shall be measured on a horizontal plane from a vertical line established at the edge of the geologically hazardous area limits (both from the top and toe of slope). In the event that a specific setback buffer is not included in the recommendation of the geological assessment, the setback buffer shall be based upon the standards contained in Chapter 18 of the International Building Code (IBC), or as the IBC is updated and amended. a. If the geological assessment recommends setback buffers that are less than the standard buffers that would result from application of Chapter 18 of the IBC, the specific rationale and basis for the reduced buffers shall be clearly articulated in the geological assessment. b. The City may require larger setback buffer widths under any of the following circumstances: i. The land is susceptible to severe erosion and erosion control measures will not effectively prevent adverse impacts. ii. The area has a severe risk of slope failure or downslope stormwater drainage impacts. iii. The increased buffer is necessary to protect public health, safety and welfare based upon findings and recommendations of the geological assessment. 3. Unless otherwise permitted as part of an approved alteration, the setback buffers required by this subsection shall be maintained in native vegetation to provide additional soil stability and erosion control. If the buffer area has been cleared, it shall be replanted with native vegetation in conjunction with any proposed development activity. 4. The City may impose seasonal restrictions on clearing and grading within 200 feet of any Geologically Hazardous Areas. 16