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Wasatch County Unincorporated
City Zoning Code

CHAPTER 16

17: GEOLOGIC HAZARDS OVERLAY ZONE GHOZ

16.17.01: PURPOSE

  1. The purpose of the geologic hazards overlay zone (GHOZ) is to provide standards, guidelines and criteria, having the effect of minimizing geologic hazards and manmade hazards, and to protect people and property while protecting the natural scenic character of the sensitive land areas not suitable for development, or suitable for development only after mitigation of hazards and ensuring the efficient expenditure of public funds.
  2. The geologic hazards overlay zone (GHOZ) is established for the following purposes:
    1. To promote the health, safety, morals and general welfare of the inhabitants of Wasatch County;
    2. To identify by map geologic hazards affecting lots in Wasatch County platted prior to the effective date of this title, to inform potential buyers of those geologic hazards, and to make recommendations to said buyers that geologic hazards reports be obtained and followed;
  3. To require that persons seeking to subdivide parcels of land within the geologic hazard overlay zone area first obtain geologic hazard reports; and
  4. To recommend that certain measures be taken to ensure that habitable structures built on land affected by geologic hazards are constructed in such a manner so as to reduce the geologic hazards to an acceptable risk. 

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.02: DEFINITIONS

As used in this title and as used in the county review and approval procedures, the following terms shall have the following meanings:

ACTIVE FAULT: A fault displaying evidence of greater than four inches (4") of displacement along one or more of its traces during Holocene time (about 11,000 years ago to the present).

ADDITION OR HOME ADDITION: Any expansion of the footprint of a structure designed for human occupancy, commercial building or essential facility, or any alteration, expansion or modification to such structures that require grading or excavation; provided, that the addition of an outside deck shall not constitute an addition unless constructing the outside deck requires grading or excavation.

BUILDABLE AREA: That portion of a site, which an engineering geology report has concluded is not impacted by geologic hazards where structures may be safely sited after consideration of setback requirements or other regulations that limit areas for building.

BUILDING ENVELOPE: The footprint of a proposed structure, the access drive thereto, areas requiring grading or excavation, and a twenty foot (20') buffer surrounding the footprint, access drive and graded or excavated areas.

CRITICAL FACILITIES: Essential facilities and lifelines, such as major utility, transportation and communication facilities, and their connections to essential facilities.

DEBRIS FLOW: A moving mass of rock fragments, soil and mud moved by an excessive amount of water and transported in an extremely fast and destructive flow through a valley or across an alluvial fan; includes a continuum of sedimentation events and processes, including debris flows, debris floods, mudflows, clear water floods, and alluvial fan flooding.

ENGINEERING GEOLOGIST: A geologist who, through education, training and experience, is able to conduct field investigations and interpret geologic conditions to assure that geologic factors affecting engineered works are recognized, adequately interpreted and presented for use in engineering practice and for the protection of the public.

ENGINEERING GEOLOGY: The application of geological data, principles and interpretation so that geological factors affecting planning, design, construction and maintenance of engineered works are properly recognized and adequately interpreted.

ESSENTIAL FACILITY: Buildings and other structures that are intended to remain operational in the event of extreme environmental loading from flood, wind, snow or earthquakes, as defined in the 2000 international uniform building code. "Essential facilities" include police stations, jails, fire stations, emergency medical facilities, search and rescue facilities, hospitals, schools (public or private), public buildings, churches, structures having an occupancy load of three hundred (300) persons or more, and other similar structures.

FAULT: A fracture in the earth's crust forming a boundary between rock or soil masses that have moved relative to each other (see definition of Active Fault).

FAULT SETBACK OR SETBACK: An area on either side of a fault within which construction of structures for human occupancy or critical facilities is not permitted.

FAULT SCARP: A steep slope or cliff formed by movement along a fault.

FAULT TRACE: The intersection of a fault plane with the ground surface, often present as a fault scarp, or lineament on aerial photographs.

FAULT ZONE: A corridor of variable width along one or more fault traces, within which deformation has occurred.

GEOLOGIC HAZARD: Surface fault rupture, liquefaction, landslide, debris flow, rockfall and/or other geologic hazards.

GEOLOGIC HAZARD REPORT: Any report obtained, either by recommendation or as required, under section 16.17.08 of this chapter.

GEOLOGIC HAZARDS OVERLAY ZONE: The total of the areas shown as potentially hazardous areas on the series of maps adopted with this title, or in other areas defined under section 16.17.03, "Applicability", of this chapter.

GEOLOGIC HAZARDS OVERLAY ZONE AREA: A portion of the potentially hazardous areas shown on the geologic hazards overlay zone maps, or in other areas defined under applicability within which a geologic hazards evaluation and/or a topographic mapping is generally recommended or required by this title prior to development.

GEOLOGIC HAZARDS OVERLAY ZONE MAPS: Refers to a series of maps adopted by this title that show areas of potential geologic hazards in Wasatch County, specifically the Timberlakes geologic hazards map dated July 1, 2002, and the high hazard areas identified in open file 319. These maps are available in the Wasatch County planning office. A smaller scale map of the geologic hazard overlay zone is attached in appendix 4.

GEOTECHNICAL ENGINEER: A professional engineer licensed in the state of Utah whose education, training and experience, is in the field of geotechnical engineering.

GEOTECHNICAL ENGINEERING: The investigation and engineering evaluation of earth materials, including soil, rock and manmade materials and their interaction with earth retention systems, foundations and other civil engineering works. The practice involves the fields of soil mechanics, rock mechanics and earth sciences, and requires knowledge of engineering laws, formulas, construction techniques and performance evaluation of engineering.

GOVERNING BODY: The county legislative body, or a future successor body to the county legislative body.

LANDSLIDE: A general term for the down slope movement of a mass of soil, surficial deposits or bedrock, including the continuum between landslides, earth flows, mudflows, debris flows and avalanches.

LIQUEFACTION: A process by which certain water saturated soils lose bearing strength because of earthquake related ground shaking and subsequent increase of groundwater pore pressure.

NONBUILDABLE AREA: That portion of a site, which an engineering geology report has concluded, may be impacted by geologic hazards, where siting of structures is not permitted, considering required setbacks, offsets or other areas as specified.

PERCENT SLOPE: The measured natural slope of the ground surface prior to any human modifications.

QUATERNARY FAULT: A fault displaying evidence of displacement in the last one and six-tenths (1.6) million years, but lacking evidence for Holocene displacement.

ROCKFALL: A mass of rock newly detached from a cliff or other very steep slope, which free falls or precipitously moves down slope; includes rock slides, rockfall, avalanches and talus.

SLOPE STABILITY: The resistance of a natural or artificial slope or other inclined surface to failure by landsliding; usually assessed under both static and dynamic/seismic (earthquake induced) conditions.

STRUCTURE DESIGNED FOR HUMAN OCCUPANCY: Any residential dwelling or any other structure used or intended for supporting or sheltering any human use or occupancy. This would include homes, home additions, and most commercial and public buildings. This would not include garages, workshops or other structures designed for minimal human occupancy or storage.

HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 2003-22 on 12/19/2003

16.17.03: APPLICABILITY

  1. This geologic hazards chapter is applicable to all lands located within the Wasatch County geologic hazard overlay zone areas, as designated on the currently adopted Wasatch County geologic overlay zone maps, on file with the county planning department. These maps currently include:
    1. Known landslides;
    2. Known active faults;
    3. Known debris flows, stream flooding and alluvial fan flooding areas; and
    4. Areas where the measured slopes are in excess of twenty five percent (25%), and those measured slopes fall within the building envelope of the proposed structure as determined by planning staff.
  2. Maps and areas within Wasatch County described above are hereby declared to be part of this title as if fully described and detailed herein.
  3. This chapter shall not apply to structures designed for human occupancy, commercial buildings or essential facilities constructed prior to the effective date of this title; except that this chapter shall apply to additions to such structures.

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.04: NOTICE

The Wasatch County geologic overlay zone maps shall be maintained in the county planning department. Where lots in the Wasatch County geologic hazard overlay zone were platted prior to the effective date of this title, a notice shall be recorded in the office of the Wasatch County recorder as to each such platted lot in substantially the following form:

    NOTICE

    This lot falls within the Wasatch County Geologic Hazard Overlay Zone. Maps and information regarding potential geologic hazards affecting this lot are on file with the Wasatch County Recorder and the Wasatch County Planning Office.

    This lot is also subject to certain recommendations set forth in the Wasatch County Geologic Hazards Overlay Zone Ordinance. It is recommended that prior to the construction of any structure designed for human occupancy on the lot, or any addition thereto, owners consult with a qualified Engineering Geologist and Geotechnical Engineer.

    It is recommended that owners obtain a Geologic Hazards Report, meeting the standards set forth in the Wasatch County Geologic Overlay Zone Ordinance. It is further recommended that the construction of any structure designed for human occupancy, or addition thereto, on this lot precisely conform to the recommendations made in the report.

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.06: WHEN GEOLOGIC HAZARD REPORTS AND DISCLOSURES ARE REQUIRED

  1. It is recommended that any applicant requesting development of a lot platted prior to the effective date of this title and within the geologic hazard overlay zone area, obtain a geologic hazard report as described in this chapter.
  2. Persons requesting subdivision approval on a parcel of land located within the geologic hazards overlay zone area shall obtain the geologic hazard reports described in this chapter. Such persons shall be subject to the review and approval procedures, and dispute resolution procedures set forth in this chapter.
  3. Any geologic hazards report obtained, whether as required or recommended by this chapter, shall be filed in the office of the Wasatch County planning department. 

HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 2003-22 on 12/19/2003

16.17.07: QUALIFICATIONS OF PERSONS PERFORMING GEOLOGIC HAZARD REPORTS

  1. An individual whose expertise is in the field of engineering geology or geotechnical engineering and who desires to perform geologic hazards evaluations in Wasatch County should present proof of their qualifications to the Wasatch County staff and be placed on a list of individuals or companies who have presented this documentation, and whose reports will be recognized by Wasatch County.
  2. A qualified engineering geologist requires at least a four (4) year degree in geology and/or engineering geology from an accredited university, and at least three (3) full years of experience in a responsible position in the field of engineering geology.
  3. A qualified geotechnical engineer requires licensure in the state of Utah with the focus of their engineering experience being in geotechnical engineering and at least four (4) years of experience in a responsible position in the field of geotechnical engineering.
  4. Upon presentation of proof of qualifications, the individual will be added to the list of those whose reports will be recognized by Wasatch County as having submitted such evidence, but shall not guarantee the quality or competence of the engineer. Submission shall only be required once to be placed on such list. Presence on such list should not be construed to be a recommendation by Wasatch County that the individual is qualified to perform the work, but only that the individual has presented documents to Wasatch County sufficient to allow Wasatch County to accept reports for processing from that individual. Proof of qualification should include:
    1. Copies of degrees received from accredited universities in an appropriate field of study pertaining to engineering geology and/or a copy of their professional engineering license.
    2. A letter from a credible person (employer, past employer, etc.) verifying your expertise and responsible experience in the field of engineering geology or geotechnical engineering.
    3. A copy of a resume no more than one year old. 

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.08: CONTENT OF GEOLOGIC HAZARD REPORTS

This section sets forth the required content for geologic hazard reports required, or in certain specified circumstances recommended, by this chapter:
  1. An engineering geology report that includes a geologic hazards evaluation shall be prepared by a qualified engineering geologist. The report shall be site specific and shall identify all known or suspected potential geologic hazards, originating on site or off site, whether previously mapped or unmapped, that may affect the particular property or surrounding properties.
  2. If the engineering geology report described in this section indicates a potential for debris flow, a debris flow evaluation and report shall include test pits or trench logs (scaled 1 inch to 5 feet, or larger), include estimates of the number and frequency of past events and their thicknesses and volume; and include estimates of the recurrence, depth and impact forces anticipated in future events. Debris flow reports shall be prepared by an engineering geologist from the list in Wasatch County, and a professional engineer licensed to practice in the state of Utah. The report should be signed by both preparers, including the professional engineer's original stamp and signature.
  3. Landslide reports shall be prepared in accordance with the Utah geological survey's "Guidelines For Evaluating Landslide Hazards In Utah" (Hylland, 1996), a copy of which may be obtained from the planning department. Landslide reports shall be prepared by a qualified engineering geologist placed on the list in Wasatch County and a professional engineer licensed to practice in the state of Utah. The report should be signed by both preparers, including the professional engineer's original stamp and signature.
  4. For any proposed subdivision located within an identified landslide area on the geologic hazards overlay zone maps adopted herewith, the entire landslide mass must be evaluated for stability.
  5. Other geologic hazards or engineering geology reports shall be prepared in accordance with the "Utah Association Of Engineering Geologists (AEG) Guidelines For Preparing Engineering Geologic Reports In Utah", a copy of which may be obtained from the planning department. These reports should be prepared by a qualified engineering geologist placed on the list in Wasatch County, and as appropriate, in conjunction with a professional engineer licensed to practice in the state of Utah, each addressing their specific areas of expertise. All reports shall be signed by the preparers. Reports signed by a professional engineer must include the professional engineer's original stamp and signature. Certification by Wasatch County consists of receiving a copy of the degree and letter verifying experience as stated above.
  6. All reports should be prepared in accordance with the accepted standard of care at the time the report is written and should address any specific additional issues identified by this title. All reports shall include, at a minimum:
    1. A geologic map, at an easily readable scale, (with reference) showing the development plans considered, including septic systems and irrigated landscaping. All reports shall be signed by the preparer;
    2. Fault study reports shall contain all requirements as described in the document "Minimum Standards For Surface Fault Rupture Studies", published by Salt Lake County, a copy of which may be obtained from the planning department. Fault study reports shall be prepared and signed by a qualified engineering geologist on the list in Wasatch County;
    3. Liquefaction analyses, if applicable, shall contain all surface geology, bedrock geology (where exposed), bedding attitudes, faults or other structural features, and the locations of any geologic hazards; liquefaction analyses will not be required on single-family residences;
    4. A detailed site map of the subject area showing any site specific mapping performed as part of the geologic evaluation, and including boundaries and features related to any geologic hazards, topography and drainage. The site map must show the location and boundaries of the geologic hazards, delineation of any recommended setback distances from geologic hazards, and recommended locations for structures. Buildable and nonbuildable areas shall be clearly identified. Scale shall be identified and must be easily readable;
    5. Trench logs and test pit logs (scale: 1 inch equals 5 feet, or larger), boring logs (scale: 1 inch equals 5 feet, or larger), aerial photographs, references with citations and other supporting information, as applicable;
    6. Field observations, including depth to groundwater, surface water conditions, bedrock outcroppings or other pertinent information that was used in establishing the results and conclusions presented in the report;
    7. Laboratory data substantiating soil and/or rock characteristics used in the engineering/geological analysis of the site;
    8. Conclusions that summarize the characteristics of the geologic hazards, and that address the potential effects of the geologic conditions and geologic hazards on the proposed development and occupants thereof in terms of risk and potential damage;
    9. Specific recommendations for avoidance or mitigation of the effects of the hazards, consistent with the purposes set forth in this chapter;
    10. Specific recommendations for additional or more detailed evaluation, as may be required to understand or quantify the hazard, evaluate whether mitigation measures are required, and evaluate mitigation options;
    11. Evidence on which recommendations and conclusions are based shall be clearly stated in the report;
    12. Additional or more detailed evaluation may be required, if recommended by the report or as advised by a review, to understand or quantify the hazard, or to evaluate whether mitigation measures recommended in the report are adequate; and
    13. A geologic hazards assessment and all recommendations and requirements given therein, shall remain valid for seven (7) years from the date of completion, unless a shorter period is specified in the report by the preparer. The exception to the seven (7) year period of validity is where a change in site conditions, change in proposed development, technical information or county policy significantly affects the technical data, analysis, conclusions or requirements of the assessment. In this case, the county may require a new or revised assessment.

HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 2003-22 on 11/24/2003

16.17.09: REVIEW AND APPROVAL PROCEDURE

  1. In order to fulfill the purposes of this chapter, county planning staff shall review any proposed subdivision or development which requires preparation of a geologic hazard report under this chapter to determine the possible risks to the safety of persons or property from geologic hazards.
  2. The county may request the Utah geological survey and/or other experts to review the report and provide additional recommendations. Any cost the county must pay for such reviews shall be paid by the applicant, prior to any further action. A copy of the geologic hazard report shall be filed in the county planning project file. A copy may also be forwarded to the Utah geological survey.
  3. The county and retained experts in their review of the geologic hazard report, and the planning staff in their consideration of the development, shall determine whether the development complies with the following standards:
    1. A suitable geologic hazard report has been prepared by a qualified professional, as defined in this chapter.
    2. The development does not present an unreasonable risk to the safety of persons or property (including buildings, storm drains, public streets, essential facilities or critical facilities, whether off site or on site), or to the natural functions of the landscape (e.g., slopes, streams or other waterways, or drainage, whether off site or on site) because of the presence of geologic hazards or because of modifications to the site due to the proposed development (including, but not limited to, grading, septic system and irrigation of landscaped areas).
    3. At the county planning staff's discretion, based upon advice from the reviewing experts, such area may be approved for development if the applicant submits substantial evidence in the engineering geology report that, using best available practices, the identified hazards can be mitigated to a level where the risk to human life and damage to property, as well as the risk to the natural functions of the site, are reduced to an acceptable and reasonable level in a manner which has a minimum effect on the natural environment. The county may, based upon information received from experts, set other requirements as are necessary to overcome any geologic hazards and to ensure that the purposes of this chapter are met. These requirements may include, but are not limited to:
      1. Additional or more detailed evaluation to understand or quantify the hazard or determine whether mitigation measures recommended in the report are adequate;
      2. Specific mitigation requirements; establishment of buildable and/or nonbuildable areas; limitations on slope grading; and/or revegetation;
      3. Other requirements such as time schedules for completion of the mitigation, phasing of development, etc.;
      4. The county planning staff may set requirements necessary to reduce the risks from geologic hazards as a condition to the approval of any development that requires a geologic hazards report; and
      5. Where mitigation requirements or conditions for use are set, issuance of certificate of occupancy will be given only after the engineering geologist, geotechnical engineer, or other party responsible for the requirements or conditions for use has provided a letter stating that they have reviewed the plans prior to development, viewed the site before and after development, and the project was completed in accordance with the conditions set in the geologic hazards report. Deviations from the approved conditions during construction must be approved by planning staff and supported by documentation from the preparer of the geologic hazards report. 
HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 23-20 on 12/20/2023

16.17.10: DISPUTE RESOLUTION PROCEDURES

  1. Disputes regarding the actual boundaries of geologic hazards may arise when:
    1. There is a conflict between the boundary lines illustrated on the geologic hazard overlay zone maps and actual field conditions;
    2. Detailed investigations show that mapped hazards are not present within a particular area;
    3. Field conditions indicate that unmapped hazards may exist that require further study.
  2. The foregoing disputes shall be resolved in accordance with the following dispute resolution process:
    1. The person disputing the geologic hazard overlay zone boundary or the presence of mapped or unmapped hazards within a particular area shall submit technical and geologic evidence to support his/her claim to the county in the form of a geologic hazard report.
    2. The county shall request the Utah geological survey and/or other experts to review the evidence prior to making a decision concerning the dispute. The cost of the review shall be paid by the person disputing the map.
    3. In the event that the expert who issued the geologic hazard report and the reviewing expert disagree, the property owner may request that a third party review be performed at their expense. In that event, the two (2) experts shall agree on a third expert to make the determination. In the event the experts cannot agree on the third party reviewer, then the chairperson of the county legislative body shall name the third party reviewer.
  3. Any decision of the county may be appealed to the Appeals Hearing Officer pursuant to the appeal procedures set forth by county ordinance. 
HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 23-20 on 12/20/2023

16.17.11: PROHIBITED ACTIVITIES

It shall be a class C misdemeanor to:
  1. Construct an essential facility (excluding transportation lines or utilities, which by their nature may cross active faults) or a structure designed for human occupancy astride an active fault, whether within or outside of the geologic hazards overlay zone area. If a fault is discovered in the excavation for such a structure, a fault study report as described in this chapter must be performed to determine if the fault is active. If the fault is active, the review and approval procedures described in this chapter shall apply. The fault study report shall establish a fault setback on either side of the fault following the requirements set forth in said report, within which no critical facilities or structures designed for human occupancy shall be allowed.
  2. Construct a structure designed for human occupancy on an active fault scarp. Footing setbacks from a fault scarp shall meet the requirements set forth in the Utah geological survey's "Guidelines For Evaluating Landslide Hazards In Utah" (Hylland, 1996) and the "Minimum Standards For Surface Fault Rupture Studies", published by Salt Lake County (both copies are available from the planning department) or the requirements of the currently adopted building code, whichever is more stringent. The planning director may increase footing setback requirements where information from a fault study report indicates slope conditions warrant a greater setback distance.
  3. Construct a critical facility, whether within or outside of the geologic hazards overlay zone area, without first obtaining from a qualified engineering geologist and geotechnical engineer a report as to the risk of liquefaction on the affected property. If the report indicates a risk of liquefaction, it shall be unlawful to commence construction of the critical facility without obtaining a liquefaction analysis as described in this chapter. For all structures where a liquefaction analysis indicates that ground settlement may be anticipated, the project structural engineer shall provide documentation that the structure is designed to accommodate the predicted ground settlement in such a manner as to be protective of life during and after the seismic event.
  4. Subdivide land in the geologic hazard overlay zone area without first complying with the requirements of this chapter and submitting to the county planning department the geologic hazard reports required by this chapter.
  5. Commence grading, filling or excavating land within the geologic hazard overlay zone area without first obtaining the required reports and submitting them to the county planning department.
  6. Where geologic hazard reports are required by this chapter, commence construction of a structure designed for human occupancy on land within the geologic hazard overlay zone area without first obtaining the required reports and submitting them to the county planning department.
  7. Fail to report to the county planning department and the county building department any geologic hazard previously unknown, but which becomes known during grading, filling, excavating, constructing or altering any structure designed for human occupancy on land within the geologic hazard overlay zone area. 

HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 2003-22 on 12/19/2003

16.17.12: PRESUMPTION, WARNING AND DISCLAIMER

Conditions described on geologic hazard maps and aerial topography maps for Wasatch County, together with applicable explanatory material, are presumed to exist for the purposes of this chapter, until substantial evidence to the contrary is submitted. This geologic hazards overlay zone chapter and the associated geologic hazard overlay zone maps represent only those potentially hazardous areas known to the county, and should not be construed to include all possible potential hazard areas. If new areas are discovered and brought to the attention of the county by reliable experts, appropriate actions will be taken to amend this chapter and the maps. The provisions of this chapter do not in any way assure or imply that areas outside its boundaries will be free from the possible adverse effects of geologic hazards. This chapter shall not create liability on the part of the county, or any officer or employee thereof, for any damages from geologic hazards that result from reliance on this chapter or any administrative requirement or decision lawfully made thereby.

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.13: SEVERABILITY

This chapter and various parts thereof are hereby declared to be severable. Should any section of this chapter be declared by a court of competent jurisdiction to be unconstitutional or otherwise invalid, such decision shall not affect the validity of the chapter as a whole, or any portion thereof, other than the section so declared to be unconstitutional or invalid. 

HISTORY
Adopted by Ord. 2-11 on 8/8/2002

16.17.14: CONFLICTS WITH OTHER REGULATIONS

This chapter is not intended to repeal, nullify or impair any existing easements, covenants or deed restrictions. In cases of conflict between the provisions of existing land use classifications, building code, development code, easements, covenants, deed restrictions or any other ordinance of the county and the geologic hazards overlay zone chapter outlined herein, this chapter shall control. This chapter shall not in any way be construed to nullify or otherwise render invalid the general prohibition of construction or development on slopes in excess of thirty percent (30%).

HISTORY
Adopted by Ord. 2-11 on 8/8/2002
Amended by Ord. 2005-18 on 3/9/2006

23-20