B. Exceptions. Grading on a land parcel, lot or project site is not subject to the requirements of Section 18.61.054C., G.1., G.2., G.4., G.5., and H.1 if any one of the following apply:
1. Exclusion of fifteen percent (15%) slopes. When all of the fifteen percent (15%) or greater slopes are excluded from that portion of the parcel, lot or project site proposed to be graded.
2. Incidental encroachment. If the grading or disturbance of fifteen percent (15%) or greater slopes does not exceed 100 square feet on an individual graded residential lot or 1,000 square feet on a mass graded subdivision or a "Development Category 1" project, as shown in the Grading Requirements Table 18.61.054-1.
3. Vehicular access. If the grading or disturbance of fifteen percent (15%) or greater slopes is limited to grading for vehicular access as follows:
a. Within an unsubdivided, single residential lot or a single residential lot not located in a mass graded subdivision:
1) A single lane, twelve feet (12') wide driveway, with a maximum six feet (6') wide graded area on either side of the driveway, that extends from the property line to the garage or carport, and no possible practicable access alternative exists that will avoid grading slopes of fifteen percent (15%) or greater; or
2) A recorded vehicle access easement that provides access to two (2) or more residential lots.
b. For a mass graded subdivision or a Development Category 1 project as set forth in the Grading Requirements Table 18.61.054-1, grading is for an access street(s) that provides access from the property line to the mass graded area. This exception does not apply if the access street(s) encroaches into twenty-five percent (25%) or greater slopes, unless there is no practicable alternative to grading twenty-five percent (25%) or greater slopes for the access street(s).
4. Existing grading. When the grading or disturbance of slopes of fifteen percent (15%) or greater is limited to areas of existing, non-permitted grading and disturbance on a lot, parcel, or project site, provided that all of the following apply:
a. The existing grading and disturbance occurred two (2) years or more before the effective date of the ordinance that establishes this provision, and
b. The existing grading and disturbance was not created during the current owner's ownership of the lot, parcel, or project site.
c. An application for a building or grading permit on a lot that meets the preceding conditions in 1) and 2) shall be accompanied by a mitigation and revegetation plan which mitigates the existing grading and disturbance in conformance with the requirements of Section 18.61.055D.
5. Building envelopes delineated on a recorded plat. If a grading envelope or building envelope is described on a lot in a subdivision plat recorded prior to July 7, 2000, the platted lot is exempt from the grading requirements of Section 18.61.054C., G.1., G.2., G.4., and G.5. However, grading within a platted building envelope on a lot is subject to the six foot (6') grading limitation in Section 18.61.054G.3.e.
6. When a lot to be individually graded is located within a CR-1 cluster development option subdivision (Section 18.09.040) or a CR-1 lot reduction option subdivision (Section 18.09.050) recorded prior to August 11, 1998; provided, however, that grading on the lot complies with the horizontal grading limitations in Section 18.61.054G.4.
a. Natural open space is required by the plat; and
b. Such natural open space is described on the plat as a common area, or an easement or a dedication to the public, or any combination thereof; and
c. The natural open space so reserved has been maintained in a substantially undisturbed condition.
C. The total area of all grading shall conform with the grading requirements in the Grading Requirements Table 18.61.054-1 except as modified by other provisions in Section 18.61.054:
Development Category | Parcel/Lot Size Per Dwelling Unit | Grading Calculation | Maximum Grading |
Development Category | Parcel/Lot Size Per Dwelling Unit | Grading Calculation | Maximum Grading |
1. Multiple dwellings/business offices/existing commercial and industrial (mass graded) | varies | 80% of the project site | 80% of the project site |
2. Single attached or detached dwelling units (mass graded subdivisions) | <20,000 sq. ft. | 50% of the project site * | 50% of the project site * |
3. Single detached dwelling units (individually graded lots) | <20,000 sq. ft. | 50% of the lot | 50% of the lot |
4. Single detached dwelling units (individually graded lots) | 20,000 sq. ft. to 43,560 sq. ft. ** | 10,000 sq. ft. or 40% of lot, whichever is greater | 10,000 - 17,424 sq. ft. |
5. Single detached dwelling units (individually graded lots) | >43,560 sq. ft. to 72,000 sq. ft. | 17,425 sq. ft. or 30% of lot, whichever is greater | 17,425 - 21,600 sq. ft. |
6. Single detached dwelling units (individually graded lots) | >72,000 sq. ft. to 144,000 sq. ft. | 21,601 sq. ft. or 17% of lot, whichever is greater | 21,601 - 24,480 sq. ft. |
7. Single detached dwelling units (individually graded lots) | >144,000 sq. ft. to 180,000 sq. ft. | 24,481 sq. ft. or 15% of lot, whichever is greater | 24,481 - 27,000 sq. ft. |
8. Single detached dwelling units (individually graded lots) | >180,000 sq. ft. | 27,001 sq. ft. or 10% of lot, whichever is greater. | 27,001 sq. ft. |
* Under Section 18.61.054.H.1., grading may be increased in 5% increments for each 10% of the site that is not on 15%+ slopes, up to a maximum of 70% of the site.
** Minimum lot size: cluster option and standards in riparian areas have their own set-aside calculations.
D. All grading shall be performed in accordance with Chapter 18.81, except as modified by this Chapter 18.61 and the Hillside Development Manual. The exceptions set forth in 18.81.020(D) do not apply to fifteen percent (15%) or greater slopes.
E. The portions of the parcel, lot or project site to be left ungraded are to remain undisturbed and are not to be used for stockpiling of materials or excess fill, construction vehicle access, storage of vehicles during construction, or similar uses. Temporary fencing shall be installed in conformance with the Hillside Development Manual at the perimeter of the area to be graded in order to prevent encroachment into the undisturbed area.
F. Cut and Fill Requirements: General Requirements:
1. Except as modified by Sections 18.61.054G, H, or I, the vertical distance of an exposed slope shall not exceed fifteen feet (15') as measured in:
a. Fill areas. Lowest adjacent finished floor elevation (F.F.E.) to bottom of slope; or
b. Fill areas. Lowest adjacent finished elevation of a deck, step or other non-vehicular paving area to the bottom of slope. The exposed slope shall be a minimum horizontal distance of twenty feet (20') from any building roof and not a part of another structure higher than five feet (5'); or
c. Cut areas. Lowest adjacent finished floor elevation (F.F.E.) to top of slope; or
d. Cut areas where finished floor elevation has been placed below natural grade: Natural grade (N.G.) to top of slope.
2. No cut and fill shall encroach upon any floodplain, except as provided for in the floodplain management regulations (Title 16) or any adjacent properties except by the mutual written consent of all parties affected. Such consent is to be filed with the development services department.
3. Excess cut or fill material shall not be disposed of over the sides of hills or ridges, or on a project site, but instead shall be hauled off the site in accordance with the requirements of Chapter 18.81 (Grading Standards).
G. Individually Graded Lots. The following provisions apply on single, unsubdivided residential lots or single residential lots not located within a mass graded subdivision:
1. Grading increases. Except as provided in paragraph G.2 of this section, the maximum grading area in the Grading Requirements Table 18.61.054-1 may be increased for:
a. Grading areas located on less than fifteen percent (15%) slopes for the following:
1) roof area of a dwelling and accessory buildings meant for human occupancy subject to a fifty percent (50%) area limitation for that portion of a roof overhang or cantilever that extends more than six feet (6') beyond exterior walls;
2) septic field, and utility areas.
b. Grading within a utility easement or a vehicular access easement that provides the only legal access to the subject lot and one (1) or more additional lots.
c. One (1) single lane, maximum twelve feet (12') wide driveway except that an increase for grading into fifteen percent (15%) or greater slopes shall be allowed only when there is no other practicable alternative to the encroachment.
2. Grading increases permitted under subsection G.1. above are prohibited when grading encroaches into a twenty-five percent (25%) or greater slope, except that the following grading of twenty-five percent (25%) or greater slopes does not prohibit the grading increases:
a. A maximum five hundred (500) square feet;
b. A single lane twelve foot (12') wide driveway with a maximum six foot (6') wide shoulder that encroaches into twenty five percent (25%) or greater slopes and there is no practicable alternative to the encroachment;
c. A utility easement, if the development services department determines that a utility trench in the driveway is not a practicable alternative;
d. A recorded vehicular access easements that provides the only legal access to 2 or more lots.
3. Cut and Fill Requirements.
a. The cut and fill requirements in Section 18.61.054F. apply, except that any exposed slope with a vertical distance greater than ten feet (10') shall include planting areas and terraced plant benches as follows:
1) a minimum six foot (6') wide planting area at the toe of the exposed slope; and
2) a minimum six foot (6') wide terraced plant bench at the ten foot (10') height of the exposed slope; and
3) planting areas and plant benches shall extend the length of the exposed slope; and
4) the planting areas and plant benches shall be vegetated with plants in conformance with the revegetation standards in Section 18.61.055D.5.
b. Exposed fill slopes shall be separated by a minimum twenty-foot (20') wide enhanced natural area buffer, except that the exposed fill slopes may be connected by a maximum six-foot (6') wide walkway in the natural area buffer.
c. Any combination of exposed slopes on a lot with a combined vertical distance greater than ten feet (10') shall have:
1) a minimum six-foot (6') wide planting area adjacent to the toe of each exposed slope; and
2) planting areas shall extend the length of their adjacent exposed slopes.
d. All planting areas shall be vegetated in conformance with the requirements of Section 18.61.055D.5.
e. The vertical distance of a driveway exposed slope shall not exceed six feet (6') measured from the outer edges of the driveway and shoulders cross section, except that the six foot (6') vertical limitation may be increased if the planning official confirms that there is no practicable alternative to the increase.
4. Grading shall not extend more than six feet (6') horizontally beyond the structural development perimeter and six feet (6') on either side of the center line of a utility trench. The six foot (6') horizontal limitation beyond the structural development perimeter may be increased to a maximum of twelve feet (12') on slopes greater than fifteen percent (15%) that extend upward and are perpendicular to the structural development perimeter.
5. Additions and expansions. New grading required for an addition or expansion on a lot inclusive of temporary access roads and construction roads shall comply with the requirements of Chapter 18.61 subject to the following provisions:
a. If new grading encroaches into 15% or greater slopes, then the grading requirements of Section 18.61.054C., G.1., and G.2. apply for the total grading area inclusive of new and existing grading.
b. If new grading does not encroach into 15% or greater slopes, then new grading is exempt from the requirements of Section 18.61.054C., G.1., and G.2.
6. Freestanding walls and retaining walls not a part of a building:
a. In a yard abutting a street, the total height of freestanding walls, retaining walls, or any vertical combination thereof that are separated horizontally from each other by less than six feet (6'), shall be a maximum six feet (6'); and
b. The total vertical distance between the highest point of a building's parapet, mansard roof, or roof ridgeline and the lowest natural grade adjacent to the building or adjacent to a freestanding wall, retaining wall, or riprap slope located less than twelve feet (12') from the building shall not exceed the maximum building height permitted by the zone.
c. The top of any freestanding wall or retaining wall not located in a yard abutting a street and not a part of the dwelling, shall not exceed ten feet (10') above the highest first floor elevation of the dwelling, except that a retaining wall more than ten feet (10') above the highest first floor elevation that is finished with a veneer rock facing is allowed.
d. All other freestanding walls and retaining walls not regulated in subsection a. through c. above shall be a maximum ten feet (10') high from existing natural grade to top of wall.
7. Mitigation of walls and riprap. Freestanding walls, retaining walls, and riprap allowed by sections 18.61.054G.6. and 18.61.055, that are more than four feet (4') high that face outward from a dwelling and are located in a yard abutting a street, and all other walls and riprap higher than six feet (6') located in other yards and that face outward from a dwelling shall include the following minimum plantings:
a. One 15-gallon can tree spaced at an average twenty five (25) horizontal feet; and
b. Four 5-gallon can shrubs between every two trees and all planting areas shall be hydroseeded;
c. These plantings shall be added within six (6) horizontal feet beyond the toe of the wall or riprap. All plantings shall be in conformance with the revegetation plants in Section 18.61.055D.5. and the requirements of the Hillside Development Manual.
8. Riprap placement. Riprap shall not be placed on slopes less than 3:1, except as part of an access bridge, apron, or flood control structure or channel that conveys runoff from off-site.
H. Mass-graded residential subdivisions. The following provisions apply to mass-graded residential subdivisions:
1. Grading increases. For each ten percent (10%) of a project site that is on less than fifteen percent (15%) slopes, the maximum grading area permitted in the Grading Requirements Table 18.61.054-1 on the project site may be increased in five percent (5%) increments, up to a maximum seventy percent (70%) of the project site, provided that:
a. The maximum amount of grading of fifteen percent (15%) or greater slopes does not exceed fifty percent (50%) of the area on the project site containing such slopes;
b. The five percent (5%) incremental increase does not apply to project sites on which any grading encroaches into twenty-five (25%) or greater slopes with the following exception:
1) When the grading and disturbance of twenty-five percent (25%) or greater slopes does not exceed five hundred (500) square feet.
2) The five percent (5%) incremental project site grading increases permitted above may apply to grading of twenty-five percent (25%) or greater slopes in excess of five hundred (500) square feet for internal project streets, but only if there is no practicable alternative to encroaching in excess of five hundred (500) square feet, and the encroachment into twenty-five percent plus (25%+) slopes for internal project streets is reviewed and approved by the DRC.
3) When the grading and disturbance of twenty-five percent (25%) or greater slopes is for access roads from the subdivision boundary to the mass graded area and there is no practical alternative to grading of 25% or greater slopes for access roads.
2. Cut and fill requirements for mass graded subdivisions. The cut and fill requirements in Section 18.61.054F. apply subject to the following provisions:
a. The vertical distance between adjacent finish floor elevations (F.F.E.) on two (2) adjoining residential lots shall be a maximum fifteen feet (15'), and
b. An exposed slope greater than ten feet (10') high shall include a minimum six foot (6') wide planting area running the length of the toe of the exposed slope; and
c. The planting area shall be planted in conformance with the vegetation requirements of Section 18.61.055D.5. and the Hillside Development Manual.
3. Perimeter Exposed Fill Slopes And Perimeter Walls:
a. The height of a perimeter wall shall not exceed six feet (6') from finished grade;
b. The height of a perimeter exposed fill slope shall not exceed six feet (6') above the average natural grade, except that the height from natural grade shall not exceed eight feet (8') over a maximum eighty feet (80') horizontal section and the horizontal section shall have a minimum six foot (6') wide planting area adjacent to the bottom of the horizontal section in conformance with the vegetation requirements of Section 18.61.055D.5. and the type and amount of planting specified for a hillside bufferyard in the HDZ Manual;
c. The combined heights of a perimeter exposed fill slope plus a connected or adjacent perimeter wall shall not exceed twelve feet (12') above the average natural grade;
d. Wherever the combined height of a perimeter exposed fill slope and a connected or adjacent perimeter wall exceeds twelve feet (12') above natural grade, the perimeter exposed fill slope and the perimeter wall shall be separated by a minimum six feet (6') wide planting area in conformance with the vegetation requirements of Section 18.61.055D.5. and the type and amount of planting specified for a hillside bufferyard in the Hillside Development Manual. The planting area and the adjacent or connected perimeter exposed fill slope may be included in the required bufferyard;
e. Except for retaining walls, perimeter exposed fill slopes shall be no steeper than three horizontal to one vertical (3:1) and vegetated in conformance with Section 18.61.055D.5. and the type and amount of planting specified for a hillside bufferyard in the Hillside Development Manual.
4. A Hillside Bufferyard in conformance with the requirements of the Hillside Development Manual is required along:
a. The boundary of a mass graded area exposed to a down-slope view from a public or private street; and
b. That portion of a mass graded subdivision that fronts on a public or private street.
5. Riprap placement. Riprap shall not be placed on perimeter exposed slopes or within a bufferyard except that riprap may be placed:
a. To stabilize 3:1 or steeper slopes adjacent to streets that access the subdivision; or
b. As part of a bridge, apron, or flood control structure or channel.
I. Development Category 1 Projects. The following provisions apply to development of multiple dwellings, business offices, commercial and industrial uses, which are described as Development Category 1 projects in the Grading Requirements Table 18.61.054-1:
1. Cut and fill requirements. Compliance with Section 18.61.054H.2.
2. Perimeter exposed slopes and perimeter walls. Compliance with Section 18.61.054H.3.
3. Hillside bufferyard. Compliance with Section 18.61.054H.4.
4. Riprap placement. Compliance with 18.61.054H.5.
(Ord. 2003-17 § 1 (part), 2003; Ord. 2000-88 § 1, 2000; Ord. 2000-52 § 1 (part), 2000)