A. Certain areas of the City are characterized by slope, vegetation, drainage, rock outcroppings, geologic conditions, and other physical factors which, if disturbed for the purposes of development, can cause physical damage to public or private property or both. Therefore, the development of such areas and adjacent land requires special care on the part of the public and private sectors.
B. The standards, guidelines and criteria established by this Chapter shall include, but not be limited to the following:
1. The protection of public from natural hazards of storm water runoff and erosion by requiring drainage facilities and the minimal removal of natural vegetation.
2. The minimization of the threat and consequential damages of fire in hillside areas by establishing fire protection measures.
3. The preservation of natural features, wildlife habitat and open space.
4. The preservation of public access to mountain areas and natural drainage channels.
5. The retention of natural topographic features such as drainage channels, streams, ridge lines, rock outcroppings, vistas, trees, and other natural plant formations.
6. The preservation and enhancement of visual and environmental quality by use of natural vegetation and the prohibition of excessive excavation and terracing.
7. The assurance of an adequate transportation system for the total hillside area to include consideration of the approved Master Street Plan of the City. This system design will consider densities and topography with minimal cuts, fills and other visible scars.
8. The establishment of on-site traffic facilities that ensure ingress and egress for vehicles including, emergency vehicles into all developed areas at any time.
9. The encouragement of a variety of development designs and concepts that are compatible with the natural terrain of the sensitive areas and will preserve open space and natural landscape.
(Ord. 76-15, 5-6-1976; amd. Ord. 85-27, 6-13-1985)
As used in this Chapter, the following words and terms shall have the meanings ascribed to them in this Section:
AVERAGE SLOPE: Shall mean and be determined by the use of the following formula:
A. S = .00229 (I) (L)
A
A
S = Average slope in percent.
.00229 = The conversion factor of square feet to acres.
A = Total number acres in the parcel.
I = Contour interval in feet. The contour interval may not exceed ten feet (10').
L = Summation of the length of all contour lines, in feet, within the parcel.
B. In the determination of the average slope, the average (A) need not include any part of the site having a slope greater than thirty percent (30%). If such areas are excluded from determination of average slope, their acreage shall not be included as part of the total area of the site for purposes of determining the number of dwelling units allowed, but may be included with individual building lots.
C. Areas with slopes exceeding thirty percent (30%) may be:
1. Placed in permanent open space and maintained by a responsible legal entity; or
2. Platted with adjacent approved building lots with an open space easement; or
3. Other proposals may be prepared by the developer and submitted for approval of the Planning Commission.
BUILDABLE LAND: That land within a lot or development site, no part of which has slope exceeding thirty percent (30%).
DEVELOPMENT SITE: Shall mean and include the total perimeters of a subdivision or a planned unit development, or a tract, lot or parcel of land intended to be used as commercial, industrial or institutional use.
GROSS ACREAGE: The total area of the development, including all rights of way and other nonresidential uses.
IMPERVIOUS MATERIALS MATTER: That is impenetrable by moisture.
NATURAL VEGETATION: This term shall include orchards, indigenous trees, shrubs, grass and perennial growth.
NET RESIDENTIAL ACREAGE: All land within a development site devoted exclusively to a residential use.
OPEN SPACE: Includes land area of the site not covered by buildings, parking structures, or accessory structures except recreational structures. May also include any combination of public, private and common spaces.
USABLE OPEN SPACE: Is that which:
A. Has been properly designed;
B. Has been provided with landscaping and perhaps other facilities; and/or
C. Has been provided with a program of continuing maintenance.
(Ord. 76-15, 5-6-1976; amd. Ord. 85-27, 6-13-1985; 1999 Code)
A. Creation: There is hereby created a Sensitive Area Overlay Zone consisting of those areas shaded on that certain plat of the City, dated May 2, 1985, which has been filed with the City Recorder and made a part hereof.
B. Jurisdiction Of Sensitive Area Overlay Zone: The provisions of this Chapter shall apply to all lands in the City which lie within the area designated on the Zoning Map as the Ogden City Sensitive Area Overlay Zone. No building or structure may be erected or reconstructed on land which is designated on the Zoning Maps of the City as sensitive area, nor shall such land be subdivided, graded or otherwise disturbed for purposes of development or subdivision, unless such construction, subdivision or disturbance is undertaken in accordance with this Chapter.
C. Effect Of Provisions: The regulations of this Chapter shall be supplemental to, and not in lieu of, the applicable zoning provisions of the use district in which the land is located and/or general provisions applicable to all zones. However, in the event of conflict between such additional provisions and the provisions of this Chapter, the more restrictive provisions shall apply.
D. Application To Previous Development: The provisions of this Chapter shall have no application to any development or other construction project which has been granted preliminary approval prior to the effective date hereof.
(Ord. 76-15, 5-6-1976; amd. Ord. 85-27, 6-13-1985)
A. Single-Family Dwelling Units:
1. Minimum Lot Size: The minimum lot size with respect to lots upon which single-family detached dwelling units are located in subdivisions or otherwise shall be determined by reference to the following table:
Average Slope Of Development Site | Minimum Lot Size | Minimum Lot Width |
0-10% | Same as underlying zone | Same as underlying zone |
10.01-20% | 15,000 sq. ft. | At least 100' at front setback line |
20.01-30% | 20,000 sq. ft. | At least 120' at front setback line |
30.01+% | Not permitted | Not permitted |
2. Planned Unit Development And Cluster Subdivision: The maximum density with respect to dwelling units per gross acre for dwelling units in a planned unit development for cluster subdivision shall be the same as that allowed for single-family detached dwellings unless otherwise approved by the planning commission.
3. Maximum Impervious Material Coverage: The maximum impervious material coverage that shall be allowed upon lots which single- family dwelling units are located shall be thirty percent (30%) of the total lot area or seven thousand five hundred (7,500) square feet, whichever is smaller, including accessory buildings, patios, and driveways; provided however, that the maximum impervious material coverage may exceed thirty percent (30%) or seven thousand five hundred (7,500) square feet upon approval of the mayor after review and recommendation by the planning commission.
4. Buildable Area:
a. Single-family dwelling structures shall be located only upon areas constituting buildable land, which area shall be fully contiguous and shall be at least five thousand (5,000) square feet in size, and shall have minimum dimension, either length or width, of fifty feet (50');
b. Single-family dwelling structures shall be set back no further than two hundred fifty feet (250') from a public or private street except by approval of the planning commission and subject to the following standards:
(1) The home is connected to city water and sewer;
(2) The access drive does not require substantial cuts or fill, but can be developed on existing topography and meet all other requirements for access in this chapter; and
(3) The driveway layout follows natural openings and does not require removal of large amounts of vegetation.
c. All accessory structures shall be located upon buildable land, unless otherwise approved by the planning commission, upon a showing by the developer that such location will not be contrary to the purposes of this chapter.
5. Flag Lot: A flag lot may be approved by the planning commission after determining that due to topographic conditions, sensitive land concerns, or other requirements of this chapter, streets cannot or should not be extended to access substantial buildable areas that would otherwise comply with the minimum lot standards. Also, the following criteria must be met:
a. Only one single-family dwelling may be constructed as a main use on a flag lot;
b. The minimum lot area, exclusive of the access stem, shall be one hundred twenty five percent (125%) of the minimum lot area required in the zoning district;
c. The width of the access stem shall be at least thirty feet (30') with a paved twenty foot (20') wide driveway and a minimum five foot (5') wide landscaped buffer on each side of the driveway. The buffer area is provided to help screen adjacent properties and to provide a drainage area for the paved portion of the access strip;
d. The planning commission may require that one access stem serve two (2) lots and that a cross access agreement be recorded. Where such access is shared, the width and frontage requirements for each property may be reduced to fifteen feet (15'). The landscape buffer shall not be required between abutting access stems operating as a shared access;
e. Approved street numbers shall be located in such a manner as to be plainly visible and legible from the street fronting the lot.
B. Multiple Units In R-2 Through R-5 Zones:
1. Maximum Lot Width And Density: Maximum lot width and maximum density shall be determined by the following table:
Average Slope Of Development Site | Minimum Lot Width | Maximum Density |
0-10% | Same as underlying zone | Same as underlying zone |
10.01-20% | 100' | Maximum density of underlying zone x 0.70 |
20.01-30% | 120' | Maximum density of underlying zone x 0.50 |
30.01+% | Not permitted | Not permitted |
2. Maximum Impervious Material Coverage: The maximum impervious material coverage that shall be allowed upon lots upon which multiple-family units are located shall be thirty percent (30%) of the total lot area.
(Ord. 76-15, 5-6-1976; amd. Ord. 85-27, 6-13-1985; Ord. 90-49, 9-27-1990; Ord. 93-34, 9-7-1993; Ord. 2001-35, 6-5-2001)
It is intended that the development standards and provisions, as set forth herein, shall be required in connection with all building and construction in the Ogden City sensitive area overlay zone.
A. Drainage And Erosion: The area of the watershed shall be used to determine the amount of stormwater runoff generated before and after construction.
1. The "rational method" or other method as approved by the city engineer shall be used in computing runoff. The basic formula for the "rational method" is:
Q = CIA in which
Q = Runoff in cubic feet per second (CFS)
C = Coefficient of runoff or the portion of stormwater that runs off a given area (the actual C value used shall be approved by the city engineer)
I = Average rainfall intensity during time of concentration for ten (10) year return period in inches per hour. The "time of concentration" shall be defined as the time required for water to flow from the most remote point of the section under consideration
A = Drainage area in acres
2. Lots shall be arranged so as to ensure adequate setbacks from drainage channels. The 100-year storm shall be that basis for calculating setbacks. No structures shall be allowed in the 100-year floodplain.
3. Facilities for the collection of stormwater runoff shall be required to be constructed on development sites and according to the following requirements:
a. Such facilities shall be the first improvement or facilities constructed on the development site;
b. Such facilities shall be designed so as to detain safely and adequately the maximum expected stormwater runoff for a 10-year storm of two (2) hour duration, and to release it at a controlled rate equal to the runoff rate generated by the site in its natural condition. Said natural runoff rate shall not exceed 0.2 cubic feet per second per acre. The facilities shall be designed to detain runoff for a sufficient length of time so as to prevent flooding and erosion during storm runoff flow periods;
c. Such facilities shall be so designed as to divert surface water away from cut faces and sloping surfaces of a fill;
d. The existing natural drainage system will be utilized, as much as possible, in its unimproved state;
e. Where drainage channels are required, wide shallow swales lined with appropriate vegetation shall be used instead of cutting narrow, deep drainage ditches;
f. Flow retarding devices, such as detention ponds and recharge berms, shall be used where practical to minimize increases in runoff volume and peak flow rate due to development. Areas which have shallow or perched groundwater or areas that are unstable must be given additional consideration. Each facility shall have an emergency overflow system to safely carry any overflow water to an acceptable disposal point.
4. Construction of the development site shall be of a nature that will minimize the disturbance of vegetation cover, especially between October 1 and April 15 of the following year.
5. Erosion control measures on the development site shall be required to minimize the solids in runoff from such areas. The detailed design system to control stormwater erosion during and after construction shall be contained in the grading and drainage report described in section 15-27-8, "Appendix A", of this chapter.
B. Vegetation And Revegetation:
1. All areas on development sites cleared of natural vegetation in the course of construction of off site improvements shall be replanted with revegetation which has good erosion control characteristics.
2. New planting shall be protected with mulch material and fertilized when in conjunction with the planting and watering schedule in subsection B5 of this section.
3. The use of persons or firms having expertise in the practice of revegetation (i.e., licensed landscape architects or nurserymen) shall supervise the planting and installation of revegetative cover.
4. Vegetation shall be removed only when absolutely necessary, e.g., for the construction of buildings, roads and filled areas.
5. After the completion of off site improvements, vegetation will be planted in all disturbed areas only during the following time periods:
a. March 15 through May 15; and
b. September 15 through October 31.
c. If irrigated, planting may be done during summer months.
d. Such vegetation shall be a mixture of plant materials, i.e., trees, shrubs, grass and forbs. Native plant materials will be preferred.
6. No vegetation shall be removed on slopes over thirty percent (30%) except as approved by the planning commission for trail and/or open space improvements.
7. Topsoil removed during construction shall be conserved for later use on areas requiring vegetation or landscaping, i.e., cut and fill slopes.
8. All disturbed soil surfaces shall be established or covered prior to November 1. If the planned impervious surfaces (i.e., road, driveways, etc.) cannot be established prior to November 1, a temporary treatment adequate to prevent erosion shall be installed on those surfaces.
9. The property owner and/or developer shall be fully responsible for any destruction of native or applied vegetation identified as necessary for retention and shall be responsible for such destroyed vegetation. They shall carry the responsibility both for employees and subcontractors from the first day of construction until the completion of off site improvements. The property owner and developer shall replace all destroyed vegetation with varieties of vegetation approved by the planning commission. The property owner shall assume responsibility upon purchase of the lot.
C. Fire Protection:
1. Areas without a recognized water supply shall meet special requirements, on an individual basis, as established by the fire department, water utility and engineering department.
2. Each development site and building permit for private lots, flag lots, and lots where the front setback is greater than fifty feet (50'), shall be reviewed by the fire department to see that it complies with requirements for fire apparatus.
3. Spark arresters shall be installed in every fireplace constructed indoor or outdoor. Screen openings in such arresters shall not be in excess of one-fourth inch (1/4") in diameter.
D. Geology:
1. Any development within a band one-eighth (1/8) of a mile on either side of a mapped fault trace must submit a geologic report as part of the development review process.
2. Development of all structures used for human occupancy shall take place fifty feet (50') or farther from any active earthquake fault trace. Active fault traces are those identified and mapped by the city or those identified by special studies required of the developer.
3. Development of all structures used for critical facilities shall take place one hundred fifty feet (150') or farther from any active earthquake fault trace. Critical facilities shall include dams, reservoirs, fuel storage facilities, power plants, nuclear reactors, police and fire stations, schools, hospitals, nursing homes, and emergency communication facilities.
4. No structures shall be built on any zones of deformation with respect to active faults. Off site improvement design will be approved by the planning commission, upon recommendation of the city engineer.
5. No structures or off site improvements shall be allowed on any active landslide area.
6. Problems associated with development on or near perched groundwater and shallow groundwater must be mitigated in a manner as approved by the planning commission.
7. No structures shall be allowed in any high hazard rockfall zone unless mitigation measures are taken to the satisfaction of the planning commission.
E. Grading, Cuts And Fill:
1. Exposed unstable surfaces of an excavation or fill shall not be steeper than one vertical to two horizontal (1:2).
2. All permanent fill shall be located so that settlements, slidings, or erosions shall not damage or cover streets, curb, gutter, sidewalks or buildings.
3. All fill and degrees of compaction shall comply with the standards of the building code, as adopted by title 16, chapter 2 of this code, or its successor provisions.
4. The top and bottom edges of slopes caused by an excavation or fill up to ten (10) vertical feet shall be three (3) horizontal feet from the property line or public right of way lines.
5. The maximum vertical height of all cuts or fills shall be ten feet (10'). Fills for slumps or other natural depressions may exceed ten feet (10') if approved by the planning commission.
6. All structures, except retaining walls or soil stabilization improvements, shall have a setback from the crest of the fill or base of the cut of a minimum distance equal to in depth of the fill or the height of the cut, unless a structurally sound retaining wall is built for the cut or fill slope. Retaining walls may be a part of the dwelling unit.
F. Streets And Ways: Streets, roadways and private accessways shall follow as nearly as possible the natural terrain. The following additional standards shall apply:
1. At least two (2) ingress and egress routes shall be provided for each subdivision or PRUD unless the number of units served is less than twenty (20) and if the likelihood of street blockages is deemed by the planning commission to be an acceptably low risk.
2. Points of access shall be provided to all developed and nondeveloped areas for emergency and firefighting equipment. Driveways located upon each lot extending from a public or private street shall have a maximum grade of ten percent (10%) and shall be of a sufficient width and design to admit and accommodate firefighting equipment.
3. Cul-de-sacs shall not exceed six hundred feet (600') in length, unless "Dead-End" signs are posted at the entrance, and shall have a fifty foot (50') radius right of way and a forty foot (40') radius improved turnaround. Stub streets that are longer than three hundred feet (300') shall have a temporary turnaround at the end thereof.
4. Centerline curvatures shall be reviewed by the city engineer for such things as design speeds, sight distances and stopping distances.
5. Variations of the street design standards developed to solve special hillside visual and functional problems may be presented to the planning commission for consideration and approval. Examples of such variations may be the use of split roadways to avoid deep cuts, one-way streets, modifications of surface drainage treatments or sidewalk design.
6. Development sites which are located near canyon trails will provide access to those trails. Parking areas may be required by the planning commission at trailheads.
7. The maximum amount of impervious surface for streets and ways shall be twenty percent (20%) of the entire development site. All streets or rights of way for vehicular traffic shall be subject to the following limitations:
a. The maximum grade of such streets or rights of way shall be ten percent (10%) except as hereafter provided;
b. The mayor, after receiving a recommendation from the fire and engineering departments, may grant approval for a grade exceeding ten percent (10%). Grades shall not exceed the grade recommended by the city engineer for private streets;
c. The provisions of this subsection shall not apply to streets or rights of way already constructed or which have heretofore been granted preliminary approval by the planning commission;
d. Roads shall be designed to meet the city road base, asphalt and compaction standards.
G. Architectural Design:
1. Buildings proposed for construction in hillside or canyon areas within the Ogden City sensitive area zone shall be designed to be visually compatible with the natural beauty of the hillsides and canyons. The use of building materials in colors that will blend harmoniously with the natural settings are encouraged. Such material as natural woods, brick (earth colors) and stone are considered to be most appropriate.
2. The planning commission shall review the design and specified exterior materials and colors for all structures other than single-family dwellings. Building permits for such structures shall not be granted until building materials and colors have been approved by the planning commission.
3. Innovative designs for single-family dwelling units, e.g., earth sheltered dwellings with grass roofs, etc., may be allowed after approval by the planning commission, provided such innovations are also allowed under the city's building code, or that they have been granted the appropriate variances.
H. On Site Development: The property owner shall be fully responsible for making all improvements in accordance with the development site approval, e.g., drainage, erosion and vegetation constraints.
I. Bond: In addition to the provisions requiring the posting of a bond as set forth elsewhere in the ordinances of the city, the property owner/developer may be required by the mayor to guarantee the completion of revegetation projects, the stabilization of grading sites, cuts and fill and construction of stormwater runoff facilities, the construction of recreation centers as required in this section. If such additional bond is required, it shall be in an amount equal to the cost of construction of such projects and shall continue for one year after the completion date of such projects, improvements or facilities.
J. Exceptions: Exceptions to the requirements and provisions as outlined in this section may be approved by the mayor; provided, that the developer or owner of such development site can demonstrate to the satisfaction of the mayor that the requested exceptions shall not be detrimental to the general well being of the neighborhood nor in violation of the stated purposes in this chapter.
(Ord. 2011-39, 6-28-2011)
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