Chapter 18.80
HILLSIDE OVERLAY ZONE (HOZ)
Sections:
18.80.030 Development and uses permitted.
18.80.050 Development and use criteria.
18.80.010 Purpose.
The hillside overlay zone applies to all areas of the city where the slope of the land is 20 percent or greater. The intent of the zone is to establish special criteria and procedures for development in a way that the potential for property damage and adverse impacts on the natural environment are reduced, so that safe, orderly and beneficial development in the zone results. For the purposes of this section, “development” is defined as any alteration of the land surface greater than two feet in depth by construction of any kind, including hand or machine grading, filling, cutting and other earth moving activities, and/or construction of a building, road, driveway, parking area or other structure. Normal landscaping activities are not regulated by this section. [Ord. 290 § 3(3.120(1)), 2006.]
18.80.020 Area affected.
Areas of land with a slope of more than 20 percent are identified on a map titled “Slope, Garibaldi, Oregon” which is contained in the comprehensive plan of the city of Garibaldi. The boundaries of this overlay district are consistent with information available to the city on the slope of parcels within the city. Boundaries may be changed where site-specific survey information shows that the slope of a given parcel of land is less than 20 percent. Where such information is provided, the requirements of the hillside overlay zone are not applicable. [Ord. 290 § 3(3.120(2)), 2006.]
18.80.030 Development and uses permitted.
Any use permitted outright or conditional use permitted in the underlying zone may be permitted within the boundaries of the hillside overlay zone, subject to the procedures and development and use criteria of GMC 18.80.040 and 18.80.050. [Ord. 290 § 3(3.120(3)), 2006.]
18.80.040 Procedure.
The requirements of the hillside overlay zone shall be met prior to the issuance of a building permit. The requirements of this section shall also be met in conjunction with any request for approval of a subdivision, or a major or minor partition, or planned unit development. Where the requirements of the hillside overlay zone are met as part of the review and approval of a subdivision, major partition, or minor partition, or planned unit development, no further review, prior to the issuance of a building permit, will be required for property located within an approved subdivision, major partition or minor partition, or planned unit development. [Ord. 290 § 3(3.120(4)), 2006.]
18.80.050 Development and use criteria.
A. The city planner, at the direction of the city council, shall require the following reports be provided by an applicant who proposes to develop land within the hillside overlay zone. The cost of all reports shall be borne by the applicant.
1. Geologic Site Investigation. This report shall include an adequate description, as defined by the building official, of the geology of the site, conclusions and recommendations regarding the effect of geologic conditions on the proposed development, and recommendations on specific engineering or construction methods which will eliminate or minimize to an acceptable level any identified geologic hazards. The report shall be prepared by a registered geologist.
2. Grading Plan. This plan shall include the following information:
a. Existing and proposed contours (five-foot intervals) of property;
b. Details of terrain and area drainage;
c. Location of any existing buildings or structures on the property where the work is to be performed, the location of any existing buildings or structures on land of adjacent owners that are within 15 feet of the property or that may be affected by the proposed grading operations, and proposed or approximate locations of structures relative to adjoining topography;
d. The direction of drainage flow and the approximate grade of all streets;
e. Limiting dimensions, elevations, or finish contours to be achieved by the grading, including all cut and fill slopes, proposed drainage channels, and related construction;
f. Detailed plans and locations of all surface and subsurface drainage devices, walls, dams, sediment basins, storage reservoirs, and other protective devices to be constructed with, or as a part of, the proposed work, together with a map showing drainage area, the complete drainage network, including outfall lines and natural drainage ways which may be affected by the proposed development, and the estimated runoff of the area served by the drains.
The grading plan shall be prepared by a registered civil engineer.
3. Erosion Control Plan. This plan shall describe measures to be taken to stabilize slopes and minimize soil erosion during construction.
B. The following requirements are applicable to geologic site investigations:
1. The burden of proof shall be upon the applicant to show construction feasibility in hazardous areas. A proposed use will only be permitted where:
a. The site investigation indicates that there is not a hazard to the use proposed on the site or to properties in the vicinity.
b. The site investigation specifies engineering or construction methods that will eliminate or minimize to an acceptable level the identified hazard.
2. Where a site investigation report concludes that an engineering solution will solve an indicated problem, the building official shall require that the additional standards and requirements set forth in the geologic hazard report be a requirement of the building permit.
3. Where the proposed development includes grading, the site investigation report shall include conclusions and recommendations concerning grading procedures as well as conclusions and recommendations concerning the adequacy of sites and streets to be developed by the proposed grading.
4. The city planner may recommend to the city council/planning commission an independent review of the site report, particularly where the geologist or engineer has a financial interest in the property to be developed. The council/commission may require the preparation of such a report prior to issuance of a building permit. The cost of the independent review shall be borne by the property owner or developer.
5. The degree of protection from problems caused by geologic hazards required by this section is considered reasonable for regulatory purposes. This chapter does not imply that uses permitted will be free from geologic hazards. This chapter shall not create liability on the part of the city or by any officer, employee or official thereof for any damages due to geologic hazards that result from reliance on this chapter or any administrative decision lawfully made.
C. The following requirements are applicable to activities undertaken in conjunction with a grading plan:
1. Cuts.
a. The slope of cut surfaces shall be not steeper than is safe for intended use and shall be not steeper than two horizontal to one vertical unless the applicant submits a geologic site investigation report stating the site has been investigated and giving an opinion that a cut at a steeper slope will be stable and not create a hazard to public or private property.
b. Cuts shall not remove the toe of any slope where a potential landslide or erosion hazard exists.
2. Fills.
a. Fill slopes shall not be constructed on natural slopes steeper than two horizontal to one vertical.
b. The ground surface shall be prepared to receive fill by removing vegetation, noncomplying fill, topsoil and other unsuitable materials, scarifying to provide a bond with the new fill and, where slopes are steeper than five to one and the height is greater than five feet, by benching into sound bedrock or other competent materials as determined by a soils engineer.
c. Detrimental amounts of organic material shall not be permitted in structural fills. No rock or similar material greater than 12 inches in diameter shall be placed in a structural fill. The building official may permit placement of larger rock if a soils engineer designs a method of placement, continually inspects the placement and certifies the stability of the fill.
d. Fills will be compacted to a minimum of 90 percent of maximum density as determined by Uniform Building Code Standard No. 70-1. An engineer shall certify all structural fill as meeting minimum bearing capacity for the intended use.
D. The following requirements are applicable to drainage facilities:
1. All cut and fill slopes shall be provided with subsurface drainage as is necessary for stability.
2. All roof and foundation drainage must be collected, controlled, and directed to either a city street, a storm drain or to a natural drainageway if it is acceptable to the public works director.
3. Other alternative methods of storm water disposal may be approved by the public works director.
E. Erosion Control Measures. The following standards are a minimum requirement for the purposes of minimizing soil erosion. The final program for soil stabilization may vary as site conditions and development programs warrant. These minimum guidelines are not intended to resolve all project soil erosion conditions. The applicant is responsible for containing all soil on the project site.
1. Prior to approval of building permit, only the removal of existing vegetation may be carried out for surveying or planning of structures. Cutting of deciduous trees over six inches in diameter and conifers over four inches at a height of four and one-half feet above ground level shall only be carried out after the approval of the building permit.
2. If topsoil is to remain stockpiled during a rainy season, seeding or other stabilization measures are required.
3. All areas that will, by necessity, be left bare after September 30th shall be seeded to a cover crop (i.e., cereal rye, annual rye grass, perennial rye grass). Mulching is an alternative to seeding.
4. Means shall be devised to prevent sediment laden water from entering any storm sewer facilities.
5. Vegetation shall be established as soon as possible after completion of grading. The building official may require the use of matting prior to seeding on certain slopes.
F. Minimum Lot Size. The minimum lot size for any structure in the hillside overlay zone shall be 8,000 square feet. Where the property proposed for development consists of smaller contiguous lots, such lots shall be aggregated to meet this minimum lot size. Lots of less than 8,000 square feet may be built upon after a variance is granted in accordance with Chapter 18.190 GMC, Variances.
G. Maximum Lot Coverage. The total amount of the lot on which structures and other impervious surfaces may be constructed shall not exceed 40 percent.
H. Yard Requirements. The minimum yard requirement for the yard abutting a street or vehicular access way is five feet. Where this standard is used, the minimum rear yard, or yard opposite the yard abutting the street or vehicular access way, shall be 30 feet. The minimum side yard shall be 10 feet.
I. Building Height. Within the hillside overlay zone, building heights of structures other than accessory buildings shall be as follows:
1. Structures which are located below or downslope from the street, road, or vehicular access way shall have a maximum height of 16 feet above the centerline of the adjacent street, road or access way.
2. Structures other than those described in subsection (I)(1) of this section shall adhere to the height requirements of the underlying zone.
(Note: Measurements shall be taken at the midpoint of the structure at its highest point perpendicular to the street.)
3. Upon completion of construction of structures 16 feet or higher, the applicant shall submit to the city’s planner an elevation certificate affirming the height standard.
J. Uncovered vehicle access structures such as bridges may be located in the front yard setback. [Ord. 304 Art. V(2), 2008; Ord. 290 § 3(3.120(5)), 2006.]