(a) General. Unless otherwise indicated on the approved grading plan, drainage facilities and terracing shall conform to the provision of this section.
(b) Terrace. Terraces at least six feet in width shall be established at not more than thirty-foot vertical intervals on all cut or fill slopes to control surface drainage and debris, except that where only one terrace is required it shall be at mid-height. For cut or fill slopes greater than sixty feet and up to 120 feet in vertical height, one terrace at approximately mid-height shall be twelve feet in width. Terrace widths and spacing for cut and fill slopes greater than 120 feet in height shall be designed by the civil engineer and approved by the building official or city engineer. Suitable access shall be provided to permit proper cleaning and maintenance.
Swales or ditches on terraces shall have a minimum gradient of five percent and must be paved with reinforced concrete not less than three inches in thickness or an approved equal paving. They shall have a minimum depth at the deepest point of one foot and a minimum paved width of five feet.
A single run of swale or ditch shall not collect runoff from a tributary area exceeding 13,500 square feet (projected) without discharging into a downdrain.
(c) Subsurface Drainage. Cut and fill slopes shall be provided with subsurface drainage as necessary for stability.
(d) General Drainage. All sites shall be developed so as to provide control of storm and surface waters. Adequate provision shall be made to prevent any storm or surface waters from damaging the face of an excavation or the sloping face of a fill. All drainage provisions shall be subject to the approval of the city engineer, and shall be of such design as to carry storm and surface waters, including storm and surface waters from properties in upstream watershed areas, to the nearest practical street, storm drain, or natural watercourse, approved by the city engineer as a safe place to deposit and receive such waters.
(e) Interceptor Drains. Paved interceptor drains shall be installed along the top of all cut slopes where the tributary drainage area above slopes towards the cut and has a drainage path greater than forty feet measured horizontally. Interceptor drains shall be paved with a minimum of three inches of concrete or gunite and reinforced. They shall have a minimum depth of twelve inches and a minimum paved width of thirty inches measured horizontally across the drain. The slope of drain shall be approved by the building official or city engineer.
(f) Roof Drainage. All storm waters falling upon roofs will be collected in eave gutters, roof drains, or other approved devices and conducted to an approved location in a manner that minimizes erosion and storm water pollution.
(g) Building Pads. Building pads shall be sloped at a minimum of two percent to the street or an approved drainage device.
(Ord. 4564 § 1 (part), 1999)