(A) Terraces: Terraces at least eight feet (8') in width shall be established at not more than twenty five feet (25') in height intervals for all cut and fill slopes exceeding thirty feet (30') in height. Where only one terrace is required, it shall be a approximately mid height. Suitable access shall be provided to permit proper cleaning and maintenance of terraces and terrace drains. Swales or ditches on terraces shall have a minimum depth of one foot (1'), a minimum longitudinal grade of four percent (4%), a maximum longitudinal grade of twelve percent (12%). Down drains or drainage outlets shall be provided at approximately three hundred foot (300') intervals along the drainage terrace.
(B) Interceptor Drains: Surface lined interceptor drains shall be provided above all cut slopes if the tributary drainage area above the cut slopes toward the cut and has a drainage path greater than forty feet (40') measured horizontally. Interceptor drains shall have a minimum of three inches (3") of concrete or gunite and be reinforced. They shall have a minimum depth of twelve inches (12") and a minimum width of thirty inches (30") measured horizontally across the drain. Actual sizes of the drains shall be verified by calculations prepared by a registered civil engineer or as approved by the city engineer.
(C) Omission Or Modification: Terraces or interceptor drains may be omitted or modified provided such is in accordance with the recommendations contained in an engineering report addressing the drainage, written by a registered civil engineer or registered geotechnical engineer competent to do so.
(D) Down Drains And Drainage Outlets: Down drains and drainage outlets for terraces and interceptor drains shall be of approved construction and materials and shall be of adequate capacity to convey the intercepted waters to the point of disposal. If the drainage discharges onto natural ground, adequate erosion protection shall be provided. (Ord. 1523, 4-11-1995)