Uses and activities allowed within designated geologically hazardous areas are those uses permitted by the zoning district, subject to the provisions of this chapter.
(Ord. 562 § 1 (part), 2006; Ord. 675 § 1 (Exh. A) (part), 2017)
A. 
Classification. Geologically hazardous areas in Bridgeport and its UGA are classified based on the provisions of the comprehensive plan. Known geologically hazardous areas within the city consist of erosion hazard areas, including steep slopes. As more information is obtained that demonstrates the existence of other types and/or areas of geologically hazardous areas, these types and/or areas shall be classified and protected in accordance with the provisions of this chapter.
B. 
The determination of the level of risk will be established through an approved geotechnical report submitted by the applicant for any development permit. The city may use on-site inspections and the information sources identified within this title as guidance in identifying the presence of potential geologically hazardous areas.
C. 
Any land containing soils, geology or slopes that meet any of the following criteria shall be classified as having a known or suspected risk of being geologically hazardous areas:
1. 
Soils classified in the soil survey of Douglas County as having a moderate or high hazard for wind and/or water erosion;
2. 
Soil complexes containing at least one soil type classified as a moderate to severe erosion hazard when occurring on slopes of fifteen percent or greater;
3. 
Any areas with slopes thirty percent and greater;
4. 
Areas of historic failures or potentially unstable slopes designated on the Natural Resource Conservation Service slide hazard area studies; and those areas mapped as slumps, earthflows, mudflows, lahars or landslides on maps published by the United States Geological Survey or Department of Natural Resources Division of Geology and Earth Resources;
5. 
Any area with a combination of:
a. 
Slopes fifteen percent or steeper, and
b. 
Impermeable soils (typically silt and clay) frequently interbedded with granular soils (predominantly sand and gravel), and
c. 
Springs or groundwater seepage;
6. 
Any area which has shown geologically significant movement during the past ten thousand years or which is underlain by mass wastage debris from that period of time;
7. 
Any area potentially unstable as a result of rapid stream incision or stream bank erosion;
8. 
Areas located in a canyon or ravine, or on a bluff;
9. 
Any area located on an alluvial fan, presently or potentially subject to inundation by debris flows or deposition of stream-transported sediments.
(Ord. 562 § 1 (part), 2006; Ord. 675 § 1 (Exh. A) (part), 2017)
Geologically hazardous areas are designated in the Comprehensive Plan based on the classification system. Map EC7 in the comprehensive plan designates geologically hazardous areas.
(Ord. 562 § 1 (part), 2006; Ord. 675 § 1 (Exh. A) (part), 2017)
The following minimum standards shall apply to all development activities occurring within designated geologically hazardous areas and their buffers.
A. 
All projects shall be evaluated to determine whether the project is proposed to be located in a geologically hazardous area, the project's potential impact on the geologically hazardous area, and the potential impact of the geologic hazard on the proposed project.
B. 
Appropriate buffer areas shall be maintained between all permitted uses and activities and designated geologically hazardous areas.
1. 
A minimum buffer of fifty feet shall be established from the top, toe and all edges of geologically hazardous areas;
2. 
Existing native vegetation within the buffer area shall be maintained;
3. 
The buffer may be reduced to a minimum of thirty feet when an applicant demonstrates, to the satisfaction of the city, that the reduction will adequately protect the proposed development and the designated geologically hazardous area;
4. 
Normal nondestructive pruning and trimming of vegetation for maintenance purposes, or thinning of limbs of individual trees to provide for a view corridor is allowed within the buffer area.
C. 
Appropriate drainage and erosion control measures, as determined by the city, shall be implemented in designated geologically hazardous areas.
1. 
All development shall submit for review and approval a drainage and erosion control plan pursuant to the provisions of this title, unless waived by the city.
2. 
All disturbed areas shall be revegetated in accordance with an approved plan, and completed within six months.
3. 
Surface drainage shall not be directed across the face of a bluff or into a ravine. If drainage must be discharged from the bluff into adjacent waters, it shall be collected above the face of the bluff and directed to the water by a sealed drain line, and provided with an energy dissipating device.
D. 
Appropriate grading and excavation measures, as determined by the city, shall be implemented in designated geologically hazardous areas.
1. 
All development shall submit for review and approval a grading and excavation plan as specified in Chapter 4.10A, unless waived by the city. There shall be minimum disturbance of trees and vegetation on steep slopes and in ravines to minimize erosion and instability.
2. 
Excavation, grading and earthwork construction in designated geologically hazardous areas shall only be allowed from April 1st to October 15th, except for the following circumstances:
a. 
Up to five thousand square feet may be cleared on any lot, subject to approval of a drainage and erosion control and grading plan as required above; and
b. 
When a qualified geotechnical engineer determines that clearing and grading before April 1st or after October 15th will not negatively impact the geologically hazardous area.
3. 
All disturbed areas shall be revegetated in accordance with an approved plan, and completed within six months.
4. 
All clearing shall be marked in the field for inspection and approval prior to alteration of the site.
5. 
The face of any cuts and/or fills on slopes will be prepared, maintained and revegetated to control against erosion.
E. 
Construction methods should be utilized which minimize risks to structures and which do not increase the risk to the site, or to adjacent properties and their structures, from the geologic hazard.
F. 
Site planning shall minimize disruption of existing topography and natural vegetation, and shall incorporate opportunities for phased clearing.
G. 
Impervious surface coverage shall be minimized.
H. 
Any limitations to site disturbance, such as clearing restrictions, imposed as a condition of development approval shall be marked in the field and approved by the city prior to undertaking the project.
I. 
A monitoring program shall be prepared for construction activities occurring in critical geologic hazard areas.
J. 
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.
(Ord. 562 § 1 (part), 2006; Ord. 675 § 1 (Exh. A) (part), 2017)