(A) (1) The subdivision shall be protected from inundation, flood sheet overflow, ponding of local storm waters, springs, and other surface waters. The design of improvements shall be such that water occurring within the subdivision will be carried off such subdivision without injury to any improvements, residential sites, or residences to be installed on sites within the subdivision or to adjoining areas.
(2) Waters occurring within the subdivision shall be carried to a storm drainage facility or to a natural watercourse by such improvements as may be required to meet the design standards set forth in this article. The drainage design within the subdivision shall accommodate anticipated future development within the drainage area. Any off-tract outlet drainage facility required to carry storm water from the proposed subdivision to a defined channel or conduit shall be made adequate for the ultimate stage of development in the drainage area.
(B) (1) Runoff quantities shall be determined by the modified rational method, using basic data supplied by the Flood Control District for the frequency of occurrence stipulated in this division.
(2) Drainage facilities directly affecting the proposed subdivision shall have the following minimum capacities:
(a) Major drainage channels and conduits shall have sufficient capacity to contain a 50 year frequency of occurrence runoff.
(b) Secondary drainage channels and conduits shall have sufficient capacity to contain a 25 year frequency of occurrence runoff.
(c) Minor drainage facilities shall have sufficient capacity to contain a 10 year frequency of occurrence runoff.
(C) Waters within street areas shall be placed in closed conduits where the maximum depth of computed flow exceeds the capacity of the gutter, creates a traffic hazard, or endangers property. Storm water in natural or artificial drainage channels shall be placed in closed conduits or concrete-lined channels where the quantity does not exceed 80 cubic feet per second, except that the Council may recommend that an existing natural watercourse endowed with significant natural beauty in the form of trees, shrubs, or scenic attractions in such instances may be utilized for an open drainage facility with such drainage improvements as may be designated by the Flood Control District when such areas are dedicated as an easement.
(D) The design of drainage channels, conduits, and appurtenances shall conform with the design standards of the Flood Control District.
(E) The proposed subdivision shall not cause or contribute to inundation or flood hazard conditions of existing inhabited areas, nor shall the improvement of the subdivision add sufficient runoff to cause damage to uninhabited areas.
(F) The Council may establish drainage fees as permitted in Article 5 of the Subdivision Map Act (Cal. Gov't Code §§ 66483 et seq.).
('66 Code, § 9-4.622) (Ord. 275-C-S, passed 3-11-75) Penalty, see § 9-4.903