The determination of design discharge of storm drainage water shall be accomplished in accordance with the following criteria:
(1) The Rational Method (Q = CIA) shall be used on small watersheds of one thousand acres (1,000) acres or less.
(2) Unit hydrographic techniques shall be used for areas greater than one thousand (1,000) acres.
The City Engineer prior to the completion of calculations shall approve the technique and data to be used for the determination of the design discharge. A complete set of all detailed calculations must be submitted to the City Engineer for approval prior to the completion of the plans for the drainage system.