Ukiah Municipal Code Art. 11 Storm Drainage

The subdivider shall provide adequate facilities for carrying waters originating above and from within the subdivision, through the subdivision and to established surface water channels. Such facilities shall be constructed in accordance with the "Standard Specifications" and to meet the minimum standards set forth in this Article.

(Ord. 533, § 4.7, adopted 1958)

Runoff shall be estimated using the Rational Method. Areas shall be determined from contour map of the subdivision and from U.S. Geological Survey Quadrangles. Rainfall intensity shall be taken from the time-intensity frequency-duration curves in the "Standard Specifications" allowing, within the subdivision, a concentration time of ten (10) minutes from roof to gutter, a 10-year frequency and a runoff constant of forty one-hundredths (0.40) for residential areas. Flow computations shall assume full developed conditions upstream.

(Ord. 533, § 4.71, adopted 1958)

All existing natural watercourses shall be carried through the subdivision over a dedicated easement. Such flow shall be in closed conduits where the flow requires a size of reinforced concrete pipe forty eight inches (48") or less.

(Ord. 533, § 4.72, adopted 1958)

Where open ditches are necessary, the easement shall be of sufficient width to allow operation of heavy mechanical equipment for clearing unless the channel is lined, in which case, access for workmen shall be provided.

(Ord. 533, § 4.73, adopted 1958)

All open ditches shall be fenced within the subdivision with chain link fence.

(Ord. 533, § 4.74, adopted 1958)

Surface runoff within the subdivision shall be handled, wherever possible, in the gutters and at intersections in valley gutters constructed in accordance with the "Standard Specifications".

(Ord. 533, § 4.75, adopted 1958)

Where surface drainage enters the submerged conduits, such entrance shall be through a catch basin constructed in accordance with the "Standard Specifications".

(Ord. 533, § 4.76, adopted 1958)

The subdivider may be required to submit to the City Engineer computations to prove that adequate drainage facilities are to be provided.

(Ord. 533, § 4.77, adopted 1958)