(A) No excavation shall be made which creates any exposed surface steeper in slope than one and one-half horizontal to one vertical. The Engineer may require an excavation to be made with a cut-face flatter in slope if the Engineer finds that the material in which the excavation is to be made is unusually subject to erosion, or if other conditions warrant a flatter slope for stability and safety.
(B) Excavations shall not extend below the angle of repose, or natural slope, of the soil under the nearest point of any footing or foundation of any building or of the soil under the nearest point of any footing or foundation of any building or structure, unless such footing or foundation is first properly underpinned or protected against settlement in a manner satisfactory to the Engineer.
(C) No cut slope shall be constructed over 30 feet in height unless the Engineer has been furnished satisfactory evidence by a qualified geologist or soils engineer that such slope will be stable. If the soil structure so requires, as determined by the Engineer, terraces not less than five feet in width shall be constructed in all cut slopes at the rate of one terrace for each 20 feet of height (or portion thereof) above 20 feet.
(`83 Code, § 15.28.170) (Ord. 85-11 § 1 (part), 1985)