The purpose of this article is to minimize hazards to the public from development activities on or adjacent to geologically hazardous areas, while allowing for natural processes and protecting stream habitats. For the purposes of this chapter, geologically hazardous areas include: erosion hazard areas, steep slope and landslide hazard areas, seismic hazard areas, mine hazard areas, channel migration zones, alluvial fan hazard areas and volcanic hazard areas.
(Ord. 1284 § 4, 2018; Ord. 1370 (Exh. B), 2025)
The administration of this article shall occur in accordance with Article I of this chapter and the standards listed below.
(1) 
Review. The applicant shall prepare a geotechnical report consistent with the requirements in LCC § 17.38.710 when required by Table 17.38-8.
(2) 
Qualified Professional. Geotechnical reports shall be prepared by a qualified professional as defined in LCC § 17.38.110. Geotechnical reports shall include a discussion of how the project incorporates mitigation sequencing and maintains the long-term stability of the geologic hazard (including any recommended buffers). Geotechnical reports shall also address the potential impact of the proposed mitigation on the hazard area, the subject property, and any affected adjacent properties.
(Ord. 1284 § 4, 2018; Ord. 1370 (Exh. B), 2025)
(1) 
Designation of Geologically Hazardous Areas. Lands that meet the criteria for geologically hazardous areas and their buffers are presented in Table 17.38-8:
Table 17.38-8
Classification
Report Required
Erosion Hazard Area
LCC § 17.38.640
Within severe and very severe erosion hazard area
Steep Slope and Landslide Hazard Area
LCC § 17.38.650
Within steep slope and landslide hazard area and buffer that is equal to the largest of:
(a) 50 feet; or
(b) The vertical height of the slope multiplied by:
(i) 1 for slopes from 15 to 40 percent.
(ii) 1.5 for slopes from 40 to 50 percent.
(iii) 2 for slopes that are greater than 50 percent.
Seismic Hazard Area
LCC § 17.38.660
No report is required in a seismic hazard area, though the applicable standards in LCC § 17.38.630 must be met.
Volcanic Hazard Area
LCC § 17.38.670
No report is required in a volcanic hazard area, though the applicable standards in LCC § 17.38.630 must be met.
Mine Hazard Area
LCC § 17.38.680
Within a classified mine hazard area.
Channel Migration Zone
LCC § 17.38.690
Within a channel migration zone.
Alluvial Fan Hazard Area
LCC § 17.38.695
Within 200 feet of an alluvial fan hazard area.
(Ord. 1284 § 4, 2018; Ord. 1370 (Exh. B), 2025)
(1) 
Standards for Certain Geologically Hazardous Areas and Their Buffers. The following standards apply to geologically hazardous areas and their required buffers, except for alluvial fan, volcano and seismic hazards:
(a) 
Development of geologically hazardous areas and their required buffers shall follow the mitigation sequence in LCC § 17.38.080(2).
(b) 
Where no reasonable alternative to the alteration of a potentially hazardous area is available, the administrator may allow the development of the area when a geotechnical report, as described in LCC § 17.38.710, is submitted by a qualified professional.
(c) 
When a geotechnical report has been submitted, the administrator may only allow the alteration when the report shows:
(i) 
The site is stable under existing conditions based on a plane of failure analysis with a factor of safety of 1.5 under seismic conditions for unconsolidated deposits or other factor of safety relevant to the type of development and hazard.
(ii) 
The alteration of vegetation will not increase the probability of the failure of the geologically hazardous area.
(iii) 
The proposed grading, excavation and structures will not increase the probability of the failure of the geologically hazardous area, and the construction of facilities to reduce risk, such as drainage systems, are effective in the absence of mechanical systems and ongoing long-term maintenance.
(iv) 
The development will incorporate measures to control additional erosion and deposition downslope or downstream, and the proposed measures to control the erosion are feasible.
(v) 
The development will not increase the risk of geologic failure on the site or adjacent properties.
(vi) 
The alteration will not adversely impact other critical areas or their associated buffers, such as wetlands, wildlife habitat areas, frequently flooded areas and critical aquifer recharge areas. When wetlands or wetland buffers are present on steep slopes of 35 percent or greater, the setback from the top of the slope shall not be less than 25 feet.
(d) 
The alteration may be approved, approved with conditions, or denied based on the administrator's evaluation of the suitability of the geotechnical report and proposed mitigation measures to protect life, safety, and stability on the subject and nearby properties.
(2) 
Standards for Seismic Hazard Areas. Developments that are proposed within seismic hazard areas shall meet the applicable provisions of the International Building Code.
(3) 
Standards for Alluvial Fan Hazard Areas. Development is not permitted within alluvial fan hazard areas, beyond what is allowed in the reasonable use provisions of this code.
(4) 
Standards for Critical Facilities. Critical facilities, as defined under Chapter 17.10 LCC (Definitions), shall only be allowed within seismic and volcanic hazard areas; provided, that no critical facilities shall be allowed within one-quarter mile of an active fault or trench. When an application for a critical facility is proposed within a seismic or volcanic hazard area, the proposal shall articulate the planned strategies to evacuate individuals within the facility, or ensure continuity of operations, in the case of a natural hazard.
(5) 
Verification of Completion of Mitigation. Upon the completion of a project, a qualified professional shall verify that any mitigation or safety measures associated with a geotechnical report have been properly implemented in accordance with LCC § 17.38.090. Depending on the nature of the mitigation (i.e., structural versus planting (of vegetation) or small or large scale improvements), the administrator may waive the five-year monitoring time frame that is specified within that section.
(Ord. 1284 § 4, 2018; Ord. 1370 (Exh. B), 2025)