(A) General. Unless otherwise indicated on the approved grading plan, drainage facilities and terracing shall conform to the provisions of this section for cut and fill slopes steeper than 1 unit vertical in 3 units horizontal (33.3% slope).
(B) Terraces. Terraces at least 6 feet in width shall be established at not more than 30-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 midheight. For cut or fill slopes greater than 60 feet and up to 120 feet in vertical height, one terrace at approximately midheight shall be 12 feet in width. Terrace widths and spacing for cut and fill slopes greater than 120 feet in height shall be designed by a registered civil engineer and approved by the Town Engineer. Suitable access shall be provided to permit proper cleaning and maintenance. Swales or ditches on terraces shall have a minimum gradient of 5% and must be paved with reinforced concrete not less than 3 inches in thickness or an approved equal type of paving. They shall have a minimum depth at the deepest point of 1 foot and a minimum paved width of 5 feet. A single run of swale or ditch shall not collect runoff from a tributary area exceeding 13,500 square feet without discharging into a down drain.
(C) Roof drainage and other surface drainage. It shall be a violation of this chapter to concentrate roof drainage or other surface drainage on a property and pass it to an adjoining property unless at least one of the following conditions are met:
(1) The drain terminates in a natural drainageway that normally carries stormwater runoff during a storm event and is capable of containing the additional runoff.
(2) The drain terminates in a constructed channel on private property that is designed to contain the stormwater runoff, including any additional created from the new drains.
(3) The drain terminates in a drainage ditch constructed in the public right-of-way.
(4) The drain terminates no closer than 20 feet from any property line and the flows are spread out to assimilate natural sheet flow, rather than a concentrated flow, prior to exiting the property.
(5) The adjacent property owner provides permission to allow the concentrated flow to enter his property. This permission must be granted in writing, recorded with the Gila County Recorder and a recorded copy of the permission presented to the Town Engineer.
(D) Subsurface drainage. Cut and fill slopes shall be provided with subsurface drainage as necessary for stability.
(E) Disposal. All drainage facilities shall be designed to carry waters to the nearest practicable drainage way approved by the Town Engineer as a safe place to deposit such waters. Erosion of ground in the area of discharge shall be prevented by installation of non-erosive down drains, rip-rap, or other approved devices.
(F) Interceptor drains. Paved interceptor drains shall be installed along the top of all cut slopes where the tributary drainage area above slopes toward the cut and has a drainage path greater than 40 feet measured horizontally. Interceptor drains shall be paved with a minimum of 3 inches of concrete or gunite and reinforced. They shall have a minimum depth of 12 inches and a minimum paved width of 30 inches measured horizontally across the drain. The slope of the drain shall be approved by the Town Engineer.
(Res. 1637, passed 2-28-02; Am. Ord. 782, passed 6-3-10)