A. Benches at least seven feet wide shall be installed on all cut and fill slopes at not more than twenty-foot vertical intervals.

B. All benches shall have city standard concrete v-ditches for drainage. The ditches shall have a minimum gradient of one-half of one percent and a maximum gradient of three and one-half percent. On slopes greater than three and one-half percent the drainage system shall be designed to accept scouring velocities.

C. All natural embankments adjacent to or within residential lots twenty feet or more in height shall have benches and v-ditches near the bottom of the slope to prevent runoff from the embankment from flowing onto the residential lot.

D. Runoff shall not be allowed to flow over the top of a slope onto the slope face.

E. Drainage facilities must discharge into existing man-made drainage facilities or into natural channels subject to the approval of the director of public works.

F. Drainage facilities must be designed to handle as a minimum the runoff computed in accordance with the requirements and standards of this chapter as specified for runoff circulations which must accompany the grading plan.

G. Finished building pads must slope a minimum of one percent towards drainage facilities unless paved areas are used or larger lots are left undeveloped and an interim one-half percent slope is satisfactory. Constructed pad elevations shall be checked by a civil engineer or licensed land surveyor prior to issuance of a building permit.

H. All drainage devices not accepted for maintenance by the city or Sonoma County water agency must be maintained by the property owner.