14.07.080 Construction standards.
(1) Maximum Slope of Cuts. The slope of cut surfaces shall be no steeper than is safe for the intended use, and shall be no steeper than two (2) horizontal to one (1) vertical (fifty (50) percent) unless the applicant furnishes a soils report justifying a steeper slope.
(a) Exceptions. A cut surface may be at a slope of one and one-half (1.5) horizontal to one (1) vertical (sixty-seven (67) percent); provided, that all the following are met:
(i) It is not intended to support structures or surcharges.
(ii) It is adequately protected against erosion.
(iii) It is no more than eight (8) feet in height.
(iv) It is approved by the building official.
(b) A cut surface in bedrock shall be permitted to be at a slope of one (1) horizontal to one (1) vertical (one hundred (100) percent).
(2) Fill. Unless otherwise recommended in the soils report, fills shall conform to provisions of this section.
(a) Surface Preparation. The ground surface shall be prepared to receive fill by removing vegetation, topsoil and other unsuitable materials, and scarifying the ground to provide a bond with the fill material.
(b) Benching. Where existing grade is at a slope steeper than five (5) horizontal to one (1) vertical (twenty (20) percent) and the depth of the fill exceeds five (5) feet, benching shall be provided in accordance with Figure J107.3. A key shall be provided which is at least ten (10) feet in width and two (2) feet in depth.
(c) Fill Material. Fill material shall not include organic, frozen or other deleterious materials. No rock or similar irreducible material greater than twelve (12) inches in any dimension shall be included in fills.
(d) Compaction. All fill material shall be compacted to ninety (90) percent of maximum density as determined by ASTM D1557, Modified Proctor, in lifts not exceeding twelve (12) inches in depth.
(e) Maximum Slope. The slope of fill surfaces shall be no steeper than is safe for the intended use. Fill slopes steeper than two (2) horizontal to one (1) vertical (fifty (50) percent) shall be justified by soils reports or engineering data.
Figure J107.3
BENCHING DETAILS
(3) Setbacks. Cut and fill slopes shall be set back from the property lines in accordance with this section. Setback dimensions shall be measured perpendicular to the property line and shall be as shown in Figure J108.1, unless substantiating data is submitted justifying reduced setbacks. The setback at the top of a cut slope shall not be less than that shown in Figure J108.1, or less than is required to accommodate any required interceptor drains, whichever is greater.
(4) Slope Protection. Where required to protect adjacent properties at the toe of a slope from adverse effects of the grading, additional protection, approved by the building official, shall be included. Such protection may include, but shall not be limited to:
(a) Setbacks greater than those required by Figure J108.1.
(b) Provisions for retaining walls or similar construction.
(c) Erosion protection of the fill slopes.
(d) Provision for the control of surface waters.
(5) Drainage and Terracing. Unless otherwise recommended by a registered design professional, drainage facilities and terracing shall be provided in accordance with the requirements of this section.
(a) Drainage facilities and terracing need not be provided where the ground slope is not steeper than three (3) horizontal to one (1) vertical (thirty-three (33) percent).
(b) Terraces at least six (6) feet in width shall be established at not more than thirty (30) foot vertical intervals on all cut or fill slopes to control surface drainage and debris. Suitable access shall be provided to allow for cleaning and maintenance. Where more than two (2) terraces are required, one (1) terrace, located at approximately mid-height, shall be at least twelve (12) feet in width. Swales or ditches shall be provided on terraces. They shall have a minimum gradient of twenty (20) horizontal to one (1) vertical (five (5) percent) and shall be paved with concrete not less than three (3) inches in thickness, or with other materials suitable to the application. They shall have a minimum depth of twelve (12) inches and a minimum width of five (5) feet.
Figure J108.1
DRAINAGE DETAILS
(c) A single run of swale or ditch shall not collect runoff from a tributary area exceeding thirteen thousand five hundred (13,500) square feet (projected) without discharging into a downdrain.
(d) Interceptor drains shall be installed along the top of cut slopes receiving drainage from a tributary width greater than forty (40) feet, measured horizontally. They shall have a minimum depth of one (1) foot and a minimum width of three (3) feet. The slope shall be approved by the building official, but shall not be less than fifty (50) horizontal to one (1) vertical (two (2) percent). The drain shall be paved with concrete not less than three (3) inches in thickness, or by other materials suitable to the application. Discharge from the drain shall be accomplished in a manner to prevent erosion and shall be approved by the building official.
(e) Drainage Across Property Lines. Drainage across property lines shall not exceed that which existed prior to grading. Excess or concentrated drainage shall be contained on site or directed to an approved drainage facility. Erosion of the ground in the area of discharge shall be prevented by installation of nonerosive downdrains or other devices.
(6) Erosion Control. The faces of cut and fill slopes shall be prepared and maintained to control erosion. This control shall be permitted to consist of effective planting. Erosion control measures need not be provided on cut slopes not subject to erosion due to the erosion-resistant character of the materials. Erosion control for the slopes shall be installed as soon as practicable and prior to calling for final inspection. Where necessary, check dams, cribbing, riprap or other devices or methods shall be employed to control erosion and provide safety. (Sec. 1 of Ord. 2007-06-05; amended by Sec. 2 (Exh. 1) of Ord. 2011-01-01)