(a) 
Geologically hazardous areas include areas susceptible to erosion, sliding, earthquakes, liquefaction, or other geological events. Geologically hazardous areas shall be classified based upon the history or existence of landslides, unstable soils, steep slopes, high erosion potential or seismic hazards. In determining the significance of a geologically hazardous area the following criteria shall be used:
(1) 
Potential economic, health, and safety impact related to construction in the area;
(2) 
Soil type, slope, vegetative cover, and climate of the area;
(3) 
Available documentation of history of soil movement, the presence of mass wastage, debris flow, rapid stream incision, stream bank erosion or undercutting by wave action, or the presence of an alluvial fan which may be subject to inundation, debris flows, or deposition of stream-transported sediments.
(b) 
The different types of geologically hazardous areas are defined as follows:
(1) 
Erosion hazard areas are as defined by the USDA Soil Conservation Service, United States Geologic Survey, or by the Department of Ecology Coastal Zone Atlas. The following classes are high erosion hazard areas:
(i) 
Class 3, class U (unstable) includes severe erosion hazards and rapid surface runoff areas;
(ii) 
Class 4, class UOS (unstable old slides) includes areas having severe limitations due to slope; and
(iii) 
Class 5, class URS (unstable recent slides).
(2) 
Landslide hazard areas shall include areas subject to severe risk of landslide based on a combination of geologic, topographic and hydrologic factors. Some of these areas may be identified in the Department of Ecology Coastal Zone Atlas, or through site-specific criteria. Landslide hazard areas include the following:
(i) 
Areas characterized by slopes greater than 15 percent; and impermeable soils (typically silt and clay) frequently interbedded with permeable granular soils (predominantly sand and gravel) or impermeable soils overlain with permeable soils; and springs or groundwater seepage;
(ii) 
Any area which has exhibited movement during the Holocene epoch (from 10,000 years ago to present) or which is underlain by mass wastage debris of that epoch;
(iii) 
Any area potentially unstable due to rapid stream incision, stream bank erosion or undercutting by wave action;
(iv) 
Any area located on an alluvial fan presently subject to or potentially subject to inundation by debris flows or deposition of stream-transported sediments;
(v) 
Any area with a slope of 40 percent or greater and with a vertical relief of 10 or more feet except areas composed of consolidated rock;
(vi) 
Any area with slope defined by the United States Department of Agriculture Soil Conservation Service as having a severe limitation for building site development; and
(vii) 
Any shoreline designated or mapped as class U, UOS, or URS by the Department of Ecology Coastal Zone Atlas.
(3) 
Slopes.
(i) 
Moderate slopes shall include any slope greater than or equal to 15 percent and less than 40 percent.
(ii) 
Steep slopes shall include any slope greater than or equal to 40 percent.
(4) 
Seismic hazard areas shall include areas subject to severe risk of earthquake damage as a result of seismic induced settlement, shaking, slope failure or soil liquefaction. These conditions occur in areas underlain by cohesionless soils of low density usually in association with a shallow groundwater table.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
Determination of a boundary of a geologically hazardous area shall be made by the Planning and Community Development Director, relying on a geotechnical or similar technical report and other information where available and pertinent. Such reports or information shall be provided by an applicant for an activity or permit at the request of the City.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
Except where regulated by other sections of this or any other title or law, the following uses shall be allowed within geologically hazardous areas when the requirements of Section 14.88.630 have been met and mitigation adequate to alleviate any other impacts has been proposed:
(a) 
Those activities allowed per Section 14.88.220.
(b) 
Any other use allowed per the zone; provided, that it meets the requirements of Section 14.88.630 and will not have a detrimental impact on the health, safety, and welfare of the public, or will not negatively impact neighboring properties.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
Development proposals on or within 200 feet of any areas which are designated as geologically hazardous, or which the City has reason to believe are geologically hazardous based on site-specific field investigation, shall be required to submit a geological assessment.
(a) 
The geological assessment shall be submitted with the minimum required content as set forth in subsection (d) of this section and in the format established by the Planning and Community Development Director, and shall be consistent with the following:
(1) 
A geotechnical letter is required when the geologist or geotechnical engineer finds that no active geological hazard area exists on or within 200 feet of the site.
(2) 
A geotechnical report is required when the geologist or geotechnical engineer finds that an active geological hazard area exists on or within 200 feet of the proposed project area.
(b) 
The Department shall review the geological assessment and either accept or reject the assessment and require revisions or additional information. When the geological assessment has been accepted, the Department shall issue a decision on the land use permit application.
(c) 
A geological assessment for a specific site may be valid for a period of up to five years when the proposed land use activity and site conditions affecting the site are unchanged. However, if any surface and subsurface conditions associated with the site change during the five-year period or if there is new information about a geological hazard, the applicant may be required to submit an amendment to the geological assessment.
(d) 
A geological assessment shall include the following minimum information and analysis:
(1) 
A field investigation that may include the use of historical air photo analysis, review of public records and documentation, and interviews with adjacent property owners or others knowledgeable about the area, etc.
(2) 
An evaluation of any areas on the site or within 200 feet of the site that are geologically hazardous as set forth in Section 14.88.600.
(3) 
An analysis of the potential impacts of the proposed development activity on any potential geological hazard that could result from the proposed development either on site or off site. For landslide hazard areas, the analysis shall consider the run-out hazard of landslide debris to the proposed development that starts upslope whether the slope is part of the subject property or starts off site.
(4) 
Identification of any mitigation measures required to eliminate potentially significant geological hazards both on the proposed development site and any potentially impacted off-site properties. When hazard mitigation is required, the mitigation plan shall specifically address how the proposed activity maintains or reduces the preexisting level of risk to the site and adjacent properties on a long term basis. The mitigation plan shall include recommendations regarding any long term maintenance activities that may be required to mitigate potential hazards.
(5) 
The geological assessment shall document the field investigations, published data and references, data and conclusions from past geological assessments, or geotechnical investigations of the site, site-specific measurements, tests, investigations, or studies, as well as the methods of data analysis and calculations that support the results, conclusions, and recommendations.
(6) 
The geological assessment shall contain a summary of any other information the geologist identifies as relevant to the assessment and mitigation of geological hazards.
(e) 
Geological assessments shall be prepared under the responsible charge of a geologist or geotechnical engineer, and shall be signed, sealed, and dated by the geologist or geotechnical engineer.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
(a) 
The setback buffer width 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.
(1) 
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.
(2) 
The City may require increased 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 geological assessment.
(b) 
Unless otherwise permitted as part of an approved alteration, the setback buffers required by this section 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.
(c) 
The City may impose seasonal restrictions on clearing and grading within 200 feet of any geologically hazardous areas.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
Unless associated with another critical area, the Planning and Community Development Director or designee may allow alterations of an area identified as a geologically hazardous area or the setback buffers specified in the IBC if an approved geotechnical report demonstrates that:
(a) 
The proposed development will not create a hazard to the subject property, surrounding properties or rights-of-way, or erosion or sedimentation to off-site properties or bodies of water;
(b) 
The proposal addresses the existing geological constraints of the site, including an assessment of soils and hydrology;
(c) 
The proposed method of construction will reduce erosion potential, landslide and seismic hazard potential, and will improve or not adversely affect the stability of slopes;
(d) 
The proposal uses construction techniques which minimize disruption of existing topography and natural vegetation;
(e) 
The proposal is consistent with the purposes and provisions of this chapter and mitigates any permitted impacts to critical areas in the vicinity of the proposal;
(f) 
The proposal mitigates all impacts identified in the geotechnical letter or geotechnical report;
(g) 
All utilities and access roads or driveways to and within the site are located so as to require the minimum amount of modification to slopes, vegetation or geologically hazardous areas; and
(h) 
The improvements are certified as safe as designed and under anticipated conditions by a geologist or geotechnical engineer.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
Modification of geologically hazardous areas shall be prohibited under the following circumstances:
(a) 
Where geologically hazardous slopes are located in a stream, wetland, and/or a fish and wildlife habitat conservation area or their required buffers, alterations of the slopes are not permitted, except as allowed in Section 14.88.220. The required buffer for such slopes shall be determined through the site-specific geological assessment, but in no case shall be less than 25 feet from the top of slopes of 25 percent and greater.
(b) 
Any proposed alteration that would result in the creation of or which would increase or exacerbate existing geological hazards, or which would result in substantial unmitigated geological hazards either on or off site shall be prohibited.
(c) 
No new development or creation of new lots is allowed that would cause foreseeable risk from geological conditions to people or improvements during the life of the development (WAC 173-26-221(2)(c)(ii)(B)).
(d) 
No new development is allowed that would require structural shoreline stabilization over the life of the development. Exceptions may be made for the limited instances where stabilization is necessary to protect allowed uses where no alternative locations are available and no net loss of ecological functions will result. (WAC 173-26-221(2)(c)(ii)(C)).
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)
(a) 
In addition to the other requirements of this chapter, as part of any approval of development on or adjacent to geologically hazardous areas or within the setback buffers required by this section:
(1) 
The City shall require:
(i) 
Geologically hazardous areas not approved for alteration and their setback buffers shall be placed in a native growth protection area as set forth in Section 14.88.290.
(ii) 
Any geologically hazardous area or required setback buffer that is allowed to be altered subject to the provisions of this chapter shall be subject to a covenant of notification and indemnification/hold harmless agreement in a form acceptable to the City Attorney. Such document shall identify any limitation placed on the approved alterations.
(2) 
The City may require:
(i) 
The presence of a geologist on the site to supervise during clearing, grading, filling, and construction activities which may affect geologically hazardous areas, and provide the City with certification that the construction is in compliance with the geologist's or geotechnical engineer's recommendations and has met approval of the geologist or geotechnical engineer, and other relevant information concerning the geologically hazardous conditions of the site.
(ii) 
Vegetation and other soil stabilizing structures or materials be retained or provided.
(iii) 
Long term maintenance of slopes and on-site drainage systems.
(b) 
If potential geologic impacts cannot be avoided by adhering to the above requirements and the other requirements of this chapter, other forms of mitigation may be considered. Applicants must provide mitigation plans exploring and analyzing any proposed mitigation measures. What is considered adequate mitigation will depend on the nature and magnitude of the potential impact. For example, some potential risk due to construction in geologically hazardous areas may be reduced through structural engineering design.
(Ord. 741, Sec. 2, 2007; Ord. 773, Sec. 2, 2008; Ord. 984 Sec. 3 (Exh. C), 2019)