Chapter 17.24
GEOLOGICALLY HAZARDOUS AREAS
Sections:
17.24.015 Classification challenge.
17.24.017 Development standards for geologically hazard areas.
17.24.020 Development standards for landslide hazard areas.
17.24.030 Development standards for erosion hazard areas.
17.24.040 Seismic hazard areas standards.
17.24.050 Review and reporting requirements.
17.24.010 Designation.
The following areas are designated as geologically hazardous areas:
A. Landslide Hazard Areas. Landslide hazard areas include areas within 300 feet of the project site that are susceptible to landslides because of any combination of bedrock, soil, slope (gradient), slope aspect, structure, hydrology, or other physical factors. Potential landslide hazard areas exhibit one or more of the following characteristics:
1. Sensitive Sloped Areas. Slopes exceeding 30 percent with a vertical relief of 10 or more feet except areas composed of competent rock and properly engineered slopes designed and approved by a geotechnical engineer licensed in the state of Washington and experienced with the site;
2. Areas designated by the Natural Resources Conservation Service as having severe limitation for building site development;
3. Areas that show evidence of historic failure or instability, as determined by the city, including but not limited to back-rotated benches on slopes; areas with structures that exhibit structural damage such as settling and racking of building foundations; and areas that have toppling, leaning, or bowed trees caused by ground surface movement;
4. Slopes greater than 15 percent that have seasonal or perennial springs or groundwater seepage caused by a more permeable geologic unit overlying a more impermeable unit;
5. Areas potentially unstable as a result of rapid stream incision, stream bank erosion, and undercutting by wave action including slopes exceeding 10 feet in height adjacent to streams, and lakes with more than a 30 percent gradient;
6. Areas located in a canyon or active alluvial fan, presently or potentially subject to inundation by debris flows or catastrophic flooding;
7. Areas that are at risk of mass wasting due to seismic forces; and
8. Slopes that are parallel or sub-parallel to planes of weakness (such as bedding planes, bedrock fracture patterns, and faults) in subsurface materials.
B. Erosion Hazard Areas. Erosion hazard areas are those areas within 200 feet of the project site with soils that exhibit the following indicators:
1. Those along shorelines that are potentially subject to channel movement due to bank destabilization and erosion, rapid incision, and shifts in location of watercourse; or
2. Those areas with soils groups designated in the Natural Resources Conservation Service “Soil Survey of Lewis County, Washington” as very severe or severe.
C. Seismic Hazard Areas. Shall be as identified in Washington State Department of Natural Resources seismic hazard maps for Western Washington and other geologic resources and include areas subject to severe risk of damage as a result of earthquake-induced ground shaking, slope failure, soil liquefaction or surface faulting including:
1. Areas subject to surface faulting during a seismic event;
2. Areas with underlying deposits indicatively classified by Washington State Department of Natural Resources as moderate or high risk of liquefaction during a seismic event;
3. Areas subject to slope failure during a seismic event. [Ord. 1122B § 15, 2025; Ord. 849B § 5, 2009.]
17.24.013 Classification.
Classification of each geologically hazardous area will be based upon the risk to development. The following categories shall be used:
A. Known or Suspected Risk. Areas that are susceptible to one or more of the hazards types described in CMC 17.24.010 shall be classified as a geologically hazardous area with a known or suspected risk and shall require a geologic site assessment as described in CMC 17.24.050.
B. Unknown Risk. Geologically hazardous areas may be present in the city that cannot readily be identified based upon the criteria of subsection (A) of this section. Geologically hazardous areas of unknown risk include areas where data is not available to determine the presence or absence of a geological hazard. The director may require a geologic site assessment and/or geotechnical report to determine the actual presence or absence of a geologically hazardous area.
C. No Risk or Low Risk. Areas classified initially as geologically hazardous areas with a known or suspected risk or unknown risk may, upon further study, actually pose no risk to development or to the public health and safety. Where the director can determine that no risk from the geologically hazardous area is present, based upon geotechnical assessments, reports, or best available science, these areas shall be classified as geologically hazardous areas determined to be of no risk or low risk. [Ord. 1122B § 15, 2025.]
17.24.015 Classification challenge.
An applicant may challenge the geologically hazardous area classification determination made by the director. Said challenge shall be in the form of a geologic site assessment or a geotechnical report under the provisions of CMC 17.24.050. If the geologic site assessment or a geotechnical report indicates that the geologically hazardous area does not exist or should be classified as no risk or low risk, the director may find that the performance standards outlined in this chapter do not apply to the site or project. [Ord. 1122B § 15, 2025.]
17.24.017 Development standards for geologically hazard areas.
A. The director may agree to alternative mitigation measures set forth by the geotechnical report if such alternative measures provide greater or equal protection than the application of the performance standards in this chapter. Development proposals may be approved pursuant to the performance standards of this chapter and/or mitigation measures of a geotechnical report if they are determined to satisfy the purposes of this chapter. Upon completion of a geotechnical report, the following performance standards shall be applied during city review of proposed development projects that are the subject of the geotechnical report. Additional mitigation measures may be required pursuant to the findings of a geotechnical report. Performance standards to be utilized include:
1. Construction methods should be used which minimize risks to structures and do not increase the risk to the site, or to adjacent properties and their structures, from the geologic hazard. Development shall not increase instability or create a hazard to the site or adjacent properties or result in a significant increase in sedimentation or erosion.
2. Site planning should minimize disruption of existing topography and vegetation and should incorporate opportunities for phased clearing and restoration.
3. Disturbed areas shall be replanted pursuant to an approved revegetation mitigation plan, prepared and implemented in accordance with CMC 17.21.087(D) and (E).
4. Excavation and grading shall be minimized. A clearing and grading schedule shall consider limitations based upon seasonal weather conditions.
5. Impervious surface coverage shall be minimized.
6. Special drainage control, beyond those required by Chapter 12.04 CMC, Article IV, may be required for projects affecting areas of geologic hazard. These plans shall indicate the effect the project may have on the hazard areas and adjacent properties and mitigating measures, with storm water detention standards based upon the technical studies required under this chapter.
7. Any limitations to site disturbance, such as clearing restrictions, imposed as a condition of development approval should be marked in the field and approved by the city prior to undertaking the project.
B. A monitoring program should be prepared for construction activities occurring in geologic hazard areas and be marked on the face of the building or grading permit.
C. All authorized clearing for roads, utilities, etc., should be limited to the minimum necessary to accomplish engineering design. Alternatives should meet the following requirements:
1. Clearing, grading, or filling of sloped sites containing erosion hazard areas shall be limited by weather conditions and an approved erosion control plan.
2. The face of cut and fill on slopes shall be prepared and maintained to control against erosion.
D. Unless otherwise directed by the administrator or recommended in the site assessment or geotechnical report pursuant to CMC 17.24.050, temporary erosion and sedimentation control shall be consistent with best management practices (BMPs) in the Stormwater Management Manual for Western Washington, current edition, as revised.
E. A development permit may be denied based upon the director’s evaluation of the inability of proposed mitigation measures to reduce risks associated with the geologically hazardous area. [Ord. 1122B § 15, 2025.]
17.24.020 Development standards for landslide hazard areas.
Uses and activities in landslide hazard areas shall conform to the following standards, or as recommended in the geotechnical report:
A. Protection of Landslide Area and Buffer. The landslide hazard area and associated buffer shall be protected from disturbance, except in compliance with the standards of this section. Modification of topography and vegetation in landslide hazard areas shall be stringently limited to provide multiple benefits of long-term stability of sensitive slopes and related benefits including reduction of erosion potential, reduction of storm water runoff, and preservation of related ecological values. Unless otherwise provided or as part of an approved alteration, removal of vegetation from a landslide hazard area or related buffer shall be prohibited. If the designated landslide hazard and buffer area lacks adequate woody vegetation to provide for stability, the director shall have the authority to require vegetation restoration or other measures to improve slope stability.
B. A buffer shall be established from all edges of landslide hazard areas to minimize or eliminate the risk of property damage, death, or injury and effects on other elements of the environment resulting from earth movement caused in whole or part by the development. The size of the buffer shall be determined as follows:
1. The buffer from the top of a slope shall be designed to protect persons and property from damage due to catastrophic slope failure and slope retreat over the lifetime of the use and provide an area of vegetation to promote shallow stability, control erosion and promote multiple benefits to wildlife and other resources. The minimum dimension of the buffer shall be equal to the greater of:
a. The distance from the edge of the active landslide hazard area as recommended in the geotechnical report based on the site-specific conditions; or
b. Fifty feet from the top of the slope.
2. The minimum buffer from the toe of a slope shall provide for safety of persons and property from the run-out resulting from slope failure and shall be the greater of:
a. The distance from the edge of the active landslide hazard area as recommended in the geotechnical report based on the site-specific conditions; or
b. Fifty feet from the toe of the slope.
3. The buffer width shall be measured on a horizontal plane from a perpendicular line established at the edge of the landslide hazard area limits (both from the top and toe of the slope).
4. Buffer Reduction. The buffer may be reduced to a minimum of 10 feet based on analysis of specific development plans provided by a qualified professional that demonstrates to the director’s satisfaction that the reduction will adequately protect the proposed development, adjacent developments and uses and other nearby critical areas.
5. Increased Buffer. The buffer may be increased where the director determines a larger buffer is necessary to prevent risk of damage to proposed and existing development.
C. Development Standards.
1. Division of land within or adjacent to landslide hazard areas and associated buffers shall be clustered to avoid landslide hazard areas and associated buffers. Land that is located partially within a landslide hazard area or its buffer may be divided; provided, that each resulting lot has sufficient buildable area outside of the landslide area and buffer with provision for drainage, erosion control and related features that will not adversely affect the stability of the landslide area.
2. Alteration of a landslide hazard area and buffer in order to accommodate structures or land alteration may be authorized only in cases where the director finds that reasonable development cannot be accommodated on portions of the site not subject to landslide hazards and buffers, and if analysis by a qualified professional as described in CMC 17.24.050(B) establishes compliance with the following standards, based on specific development plans:
a. The proposed development will not result in a risk of landslide that may affect development on the subject property or other properties in the vicinity and will not result in a greater risk or a need for increased buffers on neighboring properties. For unconsolidated deposits, development shall not decrease the factor of safety for landslide occurrences below the limits of 1.5 for static conditions and 1.2 for dynamic conditions. Analysis of dynamic conditions shall be based on a minimum horizontal acceleration as established by the current version of the International Building Code.
b. Measures to maintain slope stability, such as drainage systems, must be of a design that will ensure operation without facilities requiring regular maintenance that would jeopardize stability if the facility fails.
c. The development will not increase erosion or sedimentation risk on the site.
d. The development will not increase surface water discharge or sedimentation to adjacent properties beyond pre-development conditions.
e. Such alterations will not adversely impact other critical areas.
f. Structures shall be located on the least sensitive portion of the site and clustered where it is possible to reduce disturbance and removal of vegetation.
g. Grading shall minimize alterations to the natural contour of the slope.
h. Foundations should conform to the natural contours of the slope and foundations should be stepped/tiered where possible to conform to existing topography of the site.
i. Retaining walls shall be preferred over cut and fill and shall be incorporated into structures wherever feasible.
j. Landslide hazard areas on unconsolidated deposits with a gradient of 40 percent where the toe of slope is within the buffer area of a wetland, stream, pond or lake are not eligible for alteration of landslide hazard areas, but may be subject to alteration of buffers, subject to compliance with the standards of this chapter.
3. Critical facilities, including, but not limited to, schools, nursing homes, hospitals, police, fire and emergency response installations, and installations that produce, use, or store hazardous materials shall not be located in landslide hazard areas if there is a feasible alternative location outside the hazardous areas that would serve the intended service population. A facility may be allowed only subject to the standards in subsection (C)(2) of this section.
4. Utility lines and pipes shall be permitted in landslide hazard areas only when the applicant demonstrates that no other practical alternative is available. The line or pipe shall be located above ground and properly anchored and/or designed so that it will continue to function in the event of an underlying slide.
5. Point discharges from surface water facilities and roof drains onto or upgradient from a landslide hazard area shall be prohibited. Storm water conveyance shall be allowed only through a high-density polyethylene pipe with fuse-welded joints, or similar product that is technically equal or superior. The line or pipe shall be located above ground and properly anchored and/or designed so that it will continue to function in the event of an underlying slide.
6. Roads, driveways and other vehicular access, trails and walkways may be permitted only if the applicant demonstrates that no other feasible alternative exists, including through the provisions of Chapter 8.24 RCW and subject to the standards in subsection (C)(2) of this section. If access through a hazard area is granted, exceptions or deviations from technical standards for width or other dimensions, and specific construction standards to minimize impacts may be specified. Access roads and trails shall be engineered and built to standards that avoid the need for major repair or reconstruction beyond that which would be required in non-hazard areas and shall be:
a. Located in the least sensitive area of the site.
b. Designed to minimize topographic modification with low gradients and/or parallel to the natural contours of the site.
c. Retaining walls shall be preferred over cut and fill slopes to minimize topographic modification.
d. Clearing and grading shall minimize ground disturbance to the maximum extent feasible to accommodate allowed development and generally shall not extend more than 10 feet beyond the approved development. [Ord. 1122B § 15, 2025; Ord. 849B § 5, 2009.]
17.24.030 Development standards for erosion hazard areas.
A. Within erosion hazard areas disturbance of natural vegetation shall be limited. The following chart sets forth the maximum disturbance allowed on a site:
|
Slope |
Disturbance Allowed |
|---|---|
|
0 to 15 percent |
100 percent |
|
15 to 25 percent |
60 percent |
|
25 to 40 percent |
45 percent |
|
Greater than 40 percent |
0 percent |
1. The overall disturbance allowed on development sites which have any combination of the above slope categories shall be determined by the following formula: (square footage of the site having zero to 15 percent slopes) times 1.00 plus (square footage of site having 15 to 25 percent slopes) times 0.60 plus (square footage of site having 25 to 40 percent slopes) times 0.45 equals total allowable site disturbance.
2. Areas protected as critical areas by other provisions of this chapter shall be eliminated from the calculation of allowed site disturbance in this subsection.
3. The total allowable site disturbance limits shall be applied to the entire site and shall include all disturbance over the life of the project.
4. The disturbed area of the site shall be located within areas of the least sensitive portions of the site.
5. Areas to be preserved as undisturbed shall be located on site plans and protected from disturbance during construction and use. Areas to be preserved in subdivisions shall be indicated on the face of the plat in accordance with CMC 17.21.085, Notice on title. Disturbance limits shall be observed in subsequent development of lots.
6. Disturbance limits shall not be applied to existing single-family residential lots less than 20,000 square feet in size that were created prior to the adoption of the ordinance codified in this chapter.
B. Structures shall be located on the least sensitive portion of the site and clustered where it is possible to reduce disturbance and removal of vegetation.
C. Grading shall minimize alterations to the natural contour of the slope. Building foundations shall conform to the natural contours of the slope and be stepped/tiered to conform to existing topography of the site.
D. Retaining walls shall be preferred over cut and fill for roads, parking lots and structures. Structures on slopes in excess of 25 percent shall incorporate earth-retaining structures in buildings rather than employing freestanding earth retention structures. Clearing and grading shall minimize ground disturbance to the maximum extent feasible and generally shall not extend more than 10 feet beyond the approved development.
E. All structures or impervious surface improvements shall be required to have on-site drainage systems to meet the specifications of the public works department to control conveyance of storm water to avoid erosion hazard areas. Point discharges or overland dispersion systems from surface water facilities and roof drains onto or upstream from an erosion hazard area shall be prohibited from discharging onto slopes in excess of five percent. Storm water conveyance shall be provided to the foot of slopes and shall be allowed only through a high-density polyethylene pipe with fuse-welded joints, or similar product that is technically equal or superior, or as recommended in the geotechnical report and authorized by the city.
F. Roads, driveways and other vehicular access, trails and walkways shall be:
1. Located in the least sensitive area of the site.
2. Designed to minimize topographic modification with low gradients and/or parallel to the natural contours of the site.
3. Retaining walls shall be preferred over cut and fill slopes to minimize topographic modification.
G. Logging activity allowed on slopes exceeding 25 percent shall be partial cutting only and not clear cutting. “Partial cutting” is defined here as per WAC 222-16-010. In addition, subsequent harvest shall not create a condition inconsistent with that definition. Timber harvest in these areas shall be consistent with all applicable laws including but not limited to Chapter 222-30 WAC, Timber Harvesting, Chapter 222-34 WAC, Reforestation, and Chapter 222-38 WAC, Forest Chemicals. [Ord. 1122B § 15, 2025; Ord. 849B § 5, 2009.]
17.24.040 Seismic hazard areas standards.
Development may be allowed in seismic hazard areas when all of the following apply:
A. The applicant shall implement appropriate engineering design based on the recommendations within a geotechnical report of the best available engineering and geological practices that either eliminates or minimizes the risk of structural damage or injury resulting from seismically induced settlement or soil liquefaction, including compliance with the following criteria:
1. Subdivision within seismic hazard areas shall ensure that each resulting lot has sufficient buildable area outside of the hazard area or that appropriate limitations on building and reference to appropriate standards are incorporated into subdivision approval and may be placed as restrictions on the face of the plat;
2. Structures in seismic hazard areas shall conform to applicable analysis and design criteria of the International Building Code;
3. Public roads, bridges, utilities and trails shall be allowed when there are no feasible alternative locations and geotechnical analysis and design are provided that ensure the roadway, bridge and utility structures and facilities will not be susceptible to damage from seismic induced ground deformation. Mitigation measures shall be designed in accordance with the most recent version of the American Association of State Highway and Transportation Officials (AASHTO) Manual or other appropriate document.
B. The director may waive or reduce engineering study and design requirements for alterations in seismic hazard areas for:
1. Mobile homes;
2. Additions or alterations to existing structures that do not increase occupancy or significantly affect the risk of structural damage or injury; and
3. Buildings that are not dwelling units or used as places of employment or public assembly. [Ord. 1122B § 15, 2025; Ord. 849B § 5, 2009.]
17.24.050 Review and reporting requirements.
A. Geologic site assessments and geotechnical reports shall be prepared in compliance with the following provisions. A geotechnical report contains all of the provisions of a geologic site assessment and shall be considered to meet the requirements of a geologic site assessment.
B. Report preparers must have the following qualifications and criteria:
1. A geologic site assessment, when required, shall be prepared by either a geologist licensed by the state of Washington; an engineering geologist licensed by the state of Washington; or a professional civil engineer with geologic expertise licensed by the state of Washington.
2. A geotechnical report, when required, shall be prepared by either an engineering geologist licensed by the state of Washington or a professional civil engineer with geologic expertise licensed by the state of Washington. A civil engineer must also have five years of geotechnical experience evaluating geologically hazardous conditions and site development activities, such as landform recognition; unstable geologic units; roads; structural footings, foundations and retaining walls; swimming pools and sport courts; and other activities such as timber removal, site disturbance and mining.
C. The geologic site assessment shall include the following:
1. Evaluate the actual presence of geologically hazardous areas within or in the vicinity of the site and the need for a geotechnical report. Specifically mention the circumstances or conditions which require the report to be prepared (steep slopes, erodible soils, suspected landslide or avalanche hazard, adverse hydrologic or flood risk, etc.) and provide a description and analysis of the level of risk associated with development that complies with the standards and buffers associated with this code.
2. Evaluate safety issues related to the proposed activity’s impact on geologically hazardous areas. Address issues that could involve risk to the future occupants of the property, adjacent property, public safety, work site safety, or other critical areas.
3. Address existing geologic, topographic, and hydrogeologic conditions on the site, including an evaluation of the ability of the site to accommodate the proposed activity. Describe the proposed development, including property size and location, nature and extent of the planned development (i.e., house, garage, shop, swimming pool, etc.), and its specific location on the property. Include evidence of prior grading, excavation, cut banks, fill areas, or mining activity, and their potential impact on the project. Note and evaluate any features that could adversely affect development such as drainage gullies, erosion channeling, alluvial fans, evidence for debris flow or avalanche, surface creep, and landslides, observed or suspected spring activity, and flood risk potential.
4. A discussion of the surface and subsurface geological and engineering properties of the soils, sediments, and/or rocks on the subject property and adjacent properties and their effect on the stability of the slope. Note any areas of modified ground or fill. Where known from field inspection or reference maps and literature, include bedrock identification and age, bedding and joint attitude with respect to slope inclination, fracturing, faults and shear zones, hydrothermal alteration, weathering characteristics, presence of landslide deposits and its age and consolidation, etc. Use cross-sections if necessary for better representation of subsurface character.
5. A description of the soils in accordance with the Unified Soil Classification System. Give general soil characteristics that could affect site development (i.e., frost action and shrink/swell potential, permeability, compressibility, density or consistency, plasticity and wet/dry behavior, erodibility, etc.). Especially note the presence or suspected presence of clay-rich horizons and their position/location in the soil profile, and any indication that a building site could be subjected to soil compression or differential setting.
6. Evidence and history of avalanches, faults, significant geologic contacts, springs or seeps, landslides or other downslope soil movement, or sedimentation and alluviation, stream or channel or shoreline incision, migration, or erosion, on the subject property and adjacent properties not detailed in subsection (C)(3) of this section.
7. A discussion of seismic hazards including seismic class, liquefaction susceptibility including probable depth to groundwater, fault rupture, ground shaking, slope failure, and settlement or subsidence.
8. For landslide hazards within 300 feet of the subject property, the assessment shall include:
a. An analysis of the run-out hazard of landslide debris to the proposed development that starts upslope (whether part of the subject property or on a neighboring property) and/or the impacts of landslide run-out on downslope properties.
b. Assessments and conclusions regarding slope stability for both the existing and developed conditions including the potential types of landslide failure mechanisms (e.g., debris flow, rotational slump, translational slip, etc.) that may affect the site. The stability evaluation shall also consider dynamic earthquake loading, and shall use a minimum horizontal acceleration as established by the current version of the International Building Code.
c. For proposed development on unconsolidated deposits, analysis of whether the development results in a factor of safety for landslide occurrences below the limits of 1.5 for static conditions and 1.2 for dynamic conditions. Analysis of dynamic conditions shall be based on a minimum horizontal acceleration as established by the current version of the International Building Code.
9. A summary of the site assessment and its conclusions, mentioning the presence or absence of geological hazards and site suitability. Determine the appropriate hazard category according to the classification of the geologically hazardous area consistent with CMC 17.24.013. Include any recommendations for mitigation of potential hazards that can be dealt with without requiring a complete geotechnical report (control measures such as footing or intercept drainage systems, erosion control, debris catchment, vegetative management and restoration, and the probable need for engineering consultation and design). Include a recommendation whether additional study, including a geotechnical report pursuant to subsection (D) of this section, is required.
10. A topographic map showing the proposed development site location and approximate parcel shape location and boundaries.
11. Provide a summary of readily available existing information for the site vicinity, including geological/geotechnical reports. Cite all references and information used in the assessment preparation, such as United States Geologic Survey (USGS) and Department of Natural Resources Geologic Maps and Bulletins, soil studies, surveys and previous reports.
D. The geotechnical report determined to be required by the geologic site assessment shall include all of the information required for a geologic site assessment as well as the following:
1. Determine the appropriate hazard classification according to the designation of the geologically hazardous area consistent with CMC 17.24.010.
2. Evaluation of seismic hazards considering the proposed development.
3. Determine the appropriate application of the performance standards of this chapter and/or alternative mitigation measures that provide an equal or greater level of protection. Provide a description and analysis of the level of risk associated with the measures proposed to mitigate the hazards, ensure public safety, and protect property and other critical areas, including the risk of failure if structures, drainage systems or other facilities are not monitored, maintained, or cease to function as designed for any reasons.
4. Include a contour map of the proposed site, at a scale of one inch equals 20 feet or as deemed appropriate by the administrator. Slopes shall be clearly delineated for the ranges between 15 and 29 percent, and 30 percent or greater, including figures for a real coverage of each slope category on the site. When site-specific conditions indicate the necessity, the administrator may require the topographic data to be field surveyed.
5. A site development plan drawn to scale which shows the boundary lines and dimensions of the subject property, the location, size and type of any existing or proposed structures, off-site structures or facilities that could be impacted, impervious surfaces, wells, drain fields, drain field reserve areas, roads, easements, and utilities proposed or located on site.
6. The location of springs, seeps, or other surface expressions of groundwater. The location of surface water or evidence of seasonal surface water runoff or groundwater.
7. The extent and type of vegetative cover prior to development activity or site disturbance.
8. The proposed method of drainage and locations of all existing and proposed surface and subsurface drainage facilities and patterns, and the locations and methods for erosion control.
9. An identification of any modified ground including fill areas and assessment of potential hazards or recommendations for mitigation.
10. Information demonstrating compliance with all applicable codes and ordinances for the proposed development permit.
11. Recommendations for vegetation management or restoration or whether a vegetation specialist is required for a management plan.
E. Geologic site assessments and geotechnical reports, when completed in accordance with this chapter, shall be valid for a period of five years. A qualified professional, as outlined in subsection (B) of this section, may extend the applicability of a valid geologic site assessment or geotechnical report by five years by submittal of a letter stating the validity of the existing document and its application for the extension; provided, that such letter must address any changes in surrounding land use activity or site conditions. [Ord. 1122B § 15, 2025; Ord. 849B § 5, 2009.]