(a) The subdivider shall install storm water drainage facilities, including but not limited to ditches, storm sewers, catch basins, manholes, curb drains, and other drainage appurtenances as required by these provisions and by the Public Works Standards.
(b) Storm sewers shall be designed and installed in a manner approved by the Director as adequate to handle the required design flows, but shall not be less than twelve (12) inches in diameter. Storm sewer grades shall be designed and installed to provide a minimum full pipe velocity flow of two (2) feet per second.
(c) Storm drainage facilities shall be separate and independent of the sanitary sewer system.
(d) A storm sewer lateral shall be installed for each lot from the storm sewer to a point three (3) feet past the inside of the curb line as approved by the Director.
(e) Open storm drainage facilities such as swales, ditches, retention basins, and culverts and alteration of existing natural watercourses may be approved by the Director and the Planning Commission when such improvements are determined to be necessary for consistency or compatibility with existing improvements which are being extended, for the protection of natural features and drainage patterns, to ensure the effective functioning of the drainage facilities in the subdivision and its surrounds, or for aesthetic benefits.
(f) Facilities for the detention of storm water shall be provided where necessary to control the impacts of increased storm water leaving the site and with the purposes of:
(1) Permitting commercial, industrial, and residential development without increasing the flooding of other lands;
(2) Limiting and/or reducing the adverse impacts on receiving streams, storm sewers, and other drainage facilities caused by accelerated runoff due to development; and
(3) Providing a basis for design of storm drainage systems on land above or below undeveloped areas which will preserve the rights and options of both contributing and receiving property owners and assure the long-term adequacy of storm drainage systems.
Storm water facilities shall be designed according to criteria established in the Public Works Standards. Such criteria shall be established to ensure that peak discharge flow rates are controlled in proportion to increased runoff volume, that the peak flow rate or runoff generated by the critical storm and more frequently occurring storms does not exceed the peak flow rate or runoff from a one-year frequency, 24-hour storm occurring on the same area under pre- development conditions; and that storms of less frequent occurrence than the critical storm up to a one hundred year storm have peak runoff rates not greater than the peak flow runoff rates from the equivalent storms under pre-development conditions.
(Ord. 96-82 AC. Passed 9-16-96.)