(Title and Section Amended by Ord. No. 171,175, Eff. 7/25/96.)
91.7010.1. Height. (Amended by Ord. No. 179,324, Eff. 12/10/07, Oper. 1/1/08.) No cut slope shall exceed a vertical height of 100 feet (30 480 mm) unless horizontal benches with a minimum width of 20 feet (6096 mm), as shown in Figure D are installed at each 100 feet (30 480 mm) of vertical height.
91.7010.2. Slope. (Amended by Ord. No. 186,488, Eff. 12/27/19.) No excavation shall be made with a cut face steeper than one unit vertical in two units horizontal (50% slope).
EXCEPTION: The Department or the Board of Building and Safety Commissioners (Board), in case an appeal is made to it under LAMC Section 91.105, may permit the excavation to be made with a cut face steeper in slope than 1 unit vertical in 2 units horizontal (50% slope) if the applicant shows through investigation, subsurface exploration, analysis and report by both a soils engineer and an engineering geologist, to the Department's satisfaction, that the underlying bedrock and the materials to be exposed on the slope have strength characteristics sufficient to produce a stable slope with a factor of safety of not less than 1.5 for static loads.
Existing or proposed slopes shall be regraded or cut so as to be not steeper than the bedding planes in formation where the cut slope will lie on the dip side of the strike line or the bedding planes or other adversely oriented geologic structures shall be supported by retaining walls or buttress fills designed pursuant to the provisions of CBC Section 1807.2 or LAMC Section 91.7015.
EXCEPTION: Where special conditions warrant, the Department may approve slopes steeper than the bedding planes, or other adversely oriented geologic structures if the applicant shows through investigation, subsurface exploration, analysis and report by both a soils engineer and an engineering geologist, to the Department's satisfaction, that the slopes will have a factor of safety against sliding of not less than 1.5 for static loads.
Whenever grading at the top of any natural or manufactured slope exposes soil or bedrock material that will allow the infiltration of water in a manner that would adversely affect the stability of the slope, the exposed area shall be capped with a relatively impervious compacted soil blanket seal having a minimum thickness of two feet (610 mm). The soils engineer shall certify in writing that the blanket seal is adequate to reduce water infiltration to permissible levels.
91.7010.3. Top of Cut Slope. (Amended by Ord. No. 185,587, Eff. 7/16/18.) The top of cut slopes shall not be made nearer to a site boundary line than 1/5 of the vertical height of cut with a minimum of 2 feet (609.8 mm) and a maximum horizontal distance of 10 feet (3048 mm). The setback may need to be increased for any required interceptor drains. Setback dimensions shall be horizontal distances measured perpendicular to the site boundary. Setback dimensions shall be as shown in Figure E of this division.