B. To protect lives and property from natural or man-induced geologic or hydrologic hazards and disasters, damage due to soil hazards, forest and brush fires and to avoid financial loss resulting from development in hazard areas.

A. All developments shall be planned, designed, constructed and maintained with maximum regard to natural terrain features and topography, especially hillside areas, floodplains, and other significant land forms.

B. All grading, filling and excavating done in connection with any development shall be in accordance with Chapter 70 of the Uniform Building Code.

C. In addition to any permits required under the Uniform Building code, all developments shall be planned, designed, constructed and maintained so as to:

1. Limit the extent of disturbance of soils and site by grading, excavation and other land alterations.

2. Avoid substantial probabilities of (1) accelerated erosion; (2) pollution, contamination, or siltation of lakes, rivers and streams; (3) damage to vegetation; (4) injury to wildlife and fish habitats.

3. Minimize the removal of native vegetation that stabilize hillsides, retain moisture, reduce erosion, siltation and nutrient runoff, and preserve the natural scenic character.

7.106.030 Hill Sides.  All development proposals containing slopes 15% or greater shall include a site plan and topographic map and shall be submitted to the City Engineer for a determination of slope hazard areas.  The City Engineer shall issue written notice of the determination.  If a slope hazard exists in areas containing 15% or greater slope, but less than 20% slope, the development proposal shall be subject to the requirements of this section.   All development proposals containing slopes 20% or greater shall be subject to this section.  Slopes of properties shall be determined by the original ground slopes shown on the aerial photo used for the 1992 sewer improvements project.  A survey of the property to be developed may be required to confirm ground slope. 

A.         "Slope hazard areas" are those areas subject to a severe risk of landslide or erosion. They include any of the following areas: 

1. Any area containing slopes greater than or equal to fifteen percent and one of the following subsections; 

a. Impermeable soils (typically silt and clay) frequently interbedded with granular soils (predominately sand and gravel),

b. Any area located on areas containing soils which, according to the current version of the USDA Soil Conservation Soil Survey for Columbia County and accompanying maps, may experience severe to very severe erosion hazard,

c. Any area located on areas containing soils which, according to the current version of the USDA Soil Conservation Soil Survey for Columbia County and accompanying maps are poorly drained or subject to rapid runoff;

d. Springs or ground water seepage. 

2. Any area potentially unstable as a result of natural drainage ways, rapid stream incision, or stream bank erosion; 

3. Any area containing slopes greater than or equal to twenty percent.

B. No partition or subdivision shall create any new lot which cannot be developed under the provisions of this Section.    

C. The City Engineer may approve an application for development in a slope hazard area when the use is permitted by the base zoning and the following findings are made:   

1. The proposed landform alterations shall preserve or enhance slope stability;

2. The proposed landform alteration shall not result in erosion, stream sedimentation, ground instability, or other adverse on-site and off-site effects or hazards to life or property;

3. The proposed landform alteration addresses storm water runoff, maintenance of natural drainage ways, and does not increase existing flow intensity;

4. The proposed building site(s) is appropriately sited not requiring mass pad grading or terracing;

5. The proposed structure(s) is designed to ensure structural stability and proper drainage of foundation and crawl space areas;

6. Ground disturbing construction activities shall occur in drier weather no earlier than April 15 and no later than October 1.  

7. Where removal of natural vegetation is proposed, the areas not covered by structures or impervious surfaces shall be protected from erosion during the construction process and replanted prior to November 1 to prevent erosion. 

D. An application for development in a slope hazard area shall include: 

1. An engineering geotechnical study and supporting data demonstrating that the site is stable for the proposed use and development; 

2. The study shall include, at a minimum, geologic conditions, soil types and nature, soil strength, water table, history of area, slopes, slope stability, erosion, affects of proposed construction, and recommendations.  This study shall be completed by a registered geotechnical engineer in the state of Oregon.  The plans and specifications shall be based on the study recommendations shall be prepared and signed by a professional civil engineer registered in the State of Oregon;

3. A stabilization program for the slope hazard area based on established and proven engineering techniques that ensure protection of public and private property and prepared and signed by a professional civil engineer registered in the State of Oregon;

4. A plan showing the proposed storm water system prepared and signed by a professional civil engineer registered in the State of Oregon.  Said system will not divert storm water into slope hazard areas.

E. A structure constructed prior to the adoption of this title which would be subject to the limitations and controls imposed by this Chapter shall comply with the provisions of this Chapter if more than 50% of the existing structure is damaged or destroyed or enlargement of the footprint is proposed.

[As amended by Ordinance No. 06-619-O 7/2/06]

A. All developments shall be planned, designed, constructed, and maintained so that:

1. River and stream corridors are preserved to the maximum extent feasible and water quality is protected through adequate drainage and erosion control practices.

2. Buffers or filter strips of natural vegetation shall be retained along McBride Creek for a minimum of fifty (50) feet as measured from the top of the bank. This standard shall not be construed to mean that clearing of debris from the stream bed itself is prohibited, subject to applicable State and Federal laws.

B. The minimum required setback for buildings or structures proposed along side of McBride Creek shall be fifty (50) feet, except the Planning Commission may approve a reduction in the setback where the applicant demonstrates, through an ESEE analysis, that all impacts can be mitigated and submits a mitigation plan for approval. The ESEE analysis shall include consideration of:

1. Soil types;

2. Types and amount of existing and proposed vegetative cover;

3. Bank stability;

4. Slope of the land abutting McBride Creek;

5. Hazards of flooding; and

6. Stream character.

7. Impacts on habitat.

C. All development proposed in flood plain areas shall be governed by provisions of Chapter 7.75.

D. The siting/construction of subsurface sewage disposal fields within the flood plain shown on the FEMA maps or within one hundred (100) feet of any water course is prohibited.

E. The unauthorized diversion of impoundment of stream courses which adversely impact fisheries, wildlife, water quality or flow is prohibited.

7.106.50 Wetlands. The National Wetlands Inventory does not identify any areas of wetlands in the Columbia City. Should areas be identified as containing wetlands, development shall be in accordance with the requirements of the State of Oregon.

7.106.60 Standards for Earth Movement Hazard Areas.

A.  No development or grading shall be allowed in areas where land movement, slump or earth flow, and mud or debris flow, is observed except under one of the following conditions:

1. Stabilization of the identified hazardous condition based on established and proven engineering techniques which ensure protection of public and private property. Appropriate conditions of approval may be attached by the City.

2. An engineering geologic study approved by the City establishing that the site is stable for the proposed use and development. The study shall include the following:

a. Index map.

b. Project description, to include: location; topography, drainage, vegetation; discussion of previous work; and discussion of field exploration methods.

c. Site geology, to include: site geologic map; description of bedrock and superficial materials including artificial fill; location of any faults, folds, etc.; and structural data including bedding, jointing, and shear zones.

d. Discussion and analysis of any slope stability problems.

e. Discussion of any off-site geologic conditions that may rose a potential hazard to the site or that may be affected by on-site development.

f. Suitability of site for proposed development from geologic standpoint.

g. Specific recommendations for cut slope stability, seepage and drainage control, or other design criteria to mitigate geologic hazards.

h. Supportive data, to include: cross sections showing subsurface structure; graphic logs of subsurface explorations; results of laboratory tests; and reference.

i. Signature and certification number of engineering geologist registered in the State of Oregon.

j. Additional information or analysis as necessary to evaluate the site.

B. Vegetative cover shall be maintained or established for stability and erosion control purposes.

C. Diversion of storm water into these areas shall be prohibited.

A. The principal source of information for determining soil hazards shall be the USDA Soil Conservation Soil Survey for Columbia County and accompanying maps.

B. Where soil hazards are identified in the USDA Soil Conservation Soil Survey, approved site specific soil studies shall be required to identify the extent and severity of the hazardous conditions on the site. An engineered design shall be required to insure structural stability and property drainage of foundation and crawl space areas.

Return to Columbia City home page