Environmentally Critical Areas | Environment & Sustainability
ii. For single-family residential building permits only, the City may reduce the scope of the critical areas study if other development in the area has already provided sufficient information or if such information is otherwise readily available. b. In addition to the general requirements for critical areas studies that may be required consistent with SDC 21.03.020K.3., the critical areas study for a landslide hazard area shall include a geotechnical report prepared by a qualified professional consistent with SDC 21.04.040B.153., unless otherwise approved by the City, which also includes the following: i. A description of the extent and type of vegetative cover; ii. A description of subsurface conditions based on data from site-specific explorations; iii. Descriptions of surface and groundwater conditions, public and private sewage disposal systems, fills and excavations, and all structural improvements; iv. An estimate of the bluff retreat rate that recognizes and reflects potential catastrophic events such as seismic activity or a 100-year storm event; v. Consideration of the run-out hazard of landslide debris and/or the impacts of landslide run-out on downslope properties;
vii. An analysis of proposed surface and subsurface drainage, and the vulnerability of the site to erosion; and viii. A comprehensive study of slope stability including an analysis of proposed cuts, fills, and other site grading and construction effects where the overall minimum factor of safety for slope stability is 1.5 for static conditions and 1.1 for seismic conditions as based on current building code seismic design conditions. c. Unless otherwise provided herein or as part of an approved alteration, removal of any vegetation from a landslide hazard area or buffer shall be prohibited, except for limited removal of vegetation necessary for surveying purposes and for the removal of hazard trees determined to be unsafe by the City. The City may require the applicant to submit a report prepared by a certified arborist to confirm hazard tree conditions.
Notice to the City shall be provided prior to any vegetation removal permitted by this subsection.
d. Vegetation on slopes within a landslide hazard area or buffer that has been damaged by human activity or infested by noxious weeds may be replaced with native vegetation pursuant to an enhancement plan approved by the City pursuant to SDC 21.03.020G. The use of hazardous substances, pesticides, and fertilizers in landslide hazard areas and their buffers may be prohibited by the City. e. Alterations to landslide hazard areas and buffers may be allowed only as follows:
vi. Recommendations for building siting limitations;
Effective | January 1, 2022
Title 21: Sammamish Development Code | 85
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