§ 14.05.200. Drainage and terracing.

Unless otherwise indicated on the approved grading plan, drainage facilities and terracing shall conform to the provisions of this section.

A.

Horizontal Terrace. Horizontal terraces at least 8 feet in width shall be established at not more than 20-foot vertical intervals on all cut slopes, and 30-foot intervals on all fill slopes to control surface drainage and debris. Suitable access shall be provided to permit proper cleaning and maintenance.

B.

Swales or Ditches. Swales or ditches on terraces shall have a minimum gradient of 6 percent and must be paved with reinforced concrete, or approved equal paving not less than 3 inches in thickness. They shall have an adequately sized cross-section to handle storm water runoff collected on the slope for a design storm with a return interval of at least 25 years and a duration of 6 hours and shall have a minimum depth at the deepest point of 18 inches and a minimum paved width of 5 feet. A single run of swale or ditch shall not collect runoff from a tributary area projected to exceed 13,500 square feet without discharging into a down drain.

C.

Subsurface Drainage. Cut and fill slopes shall be provided with approved subsurface drainage as necessary for stability.

D.

Drainage Diversion. Swales, berms or other devices approved by the building official shall be installed at the top of all slopes where surface runoff may flow uncontrolled over the slope face. Such diversion must be approved by the building official and be designed to convey runoff from the tributary area of a design storm.

E.

Slope Toe Protection. The toe of all slopes shall be protected from erosion by surface runoff as approved by the building official.

F.

Maintenance of Protective Devices. Any property on which grading has been performed pursuant to a permit issued under this chapter shall be maintained in good condition, and all drainage structures, vegetation, irrigation systems and other protective devices when on the approved grading plans shall be repaired whenever necessary.

(Ord. 7127 § 5 (part), 2007: Ord. 6483 § 2 (part), 1992)