A. A Geologic Hazard Study shall be required in conjunction with the City's review of the following type of applications or hazard areas:
1. An application where any portion of the land is within the HS-O district, the SS-O district, or a 100-year floodplain;
2. An application where any portion of the land is within Potential Landslide Susceptibility and Mine Subsidence areas on maps published by the Colorado Geological Survey; or
3. An application where the owner, applicant, or City staff are aware that the land contains any of the following:
a. Existing or proposed slopes exceeding thirty-three (33) percent or that are otherwise unstable or potentially unstable;
b. Underground mining or subsidence activity;
c. A history of a landfill or uncontrolled or undocumented fill activity; or
d. Other geologic hazards that pose a risk to the proposed project development on land with seismicity, collapsible or compressible soils, shallow water table or springs, steeply dipping bedrock, expansive soils, or expansive bedrock that cannot be mitigated with standard foundation design/construction practices.
B. If required by Subsection A above, a Geologic Hazard Study shall be required in conjunction with the City's review of the following type of applications:
1. Rezoning requests when the Manager or City Engineer determine that a potential a geological hazard is present;
2. New or updated Land Use Plans;
3. Final Plats when a geologic hazard study for the property has not previously been reviewed by the City or if assumptions and recommendations that were in place at the time a previously accepted geological hazard study are no longer valid;
4. Development Plans (including expired Development Plans which are being reinstated) are required to submit a Geologic Hazard Study. If a previous Geologic Hazard Study was submitted with a Development Plan, but the Study was based on assumptions and recommendations that are no longer valid a new Geologic Hazard Study is required with the Development Plan submittal; and
5. Public improvement construction drawings.
C. The City Engineer may request a site-specific Geologic Hazard Study in conjunction with a Building Permit for a new, reconstruction, or an expansion of the building footprint or deck where no previous Geologic Hazard Study has been reviewed by the City as part of the zone change, Development Plan, or Final Plat if one of the following conditions apply:
1. Changes in drainage pattern or water flow in an area of landslide susceptibility; or
2. Excavation or vertical penetration greater than three (3) feet in depth on existing slope of fifteen (15) percent grade or steeper.
D. A Geological Hazard Study is not required in the following situations:
1. Replats of previous subdivisions in which buildings exist on the proposed lots and no new structures (not including fences) or new building sites are being created; or
2. Development Plans that do not propose new building(s) or additions to existing building(s) and no significant grading is to occur on site.
E. Where subdivision plats do not propose new building sites, the Manager and City Engineer may allow the Geologic Hazard Study to be delayed until the submittal of the Development Plan if the subdivision plat was submitted in conjunction with a Land Use Plan and the Geologic Hazard Report was determined by City Engineering staff not to be needed at time of Land Use Plan.
F. Geologic Hazard Waivers:
1. The requirement for a Geologic Hazard Study may be waived if the following conditions exist:
a. Land Use Plans, Development Plans, or subdivision plats for which Geologic Hazard Studies have been previously prepared and reviewed and which are still considered by the City Engineer as relevant. The City Engineer may request a validation letter for previously approved geologic hazard report or may require a new Geologic Hazard Study; and
b. A geologic hazard waiver is approved for development proposals for sites that do not exhibit characteristics listed within Subsection A.3 above.
2. To obtain a waiver, the applicant shall submit a waiver request, which states the project meets the above noted criteria, and is prepared by a professional geologist or geotechnical engineer, who meets the qualifications listed in Section 7.4.503 (Preparation of Geological Studies and Report Guidelines) below. (Ord. 23-03)