A. On-site retention of stormwater shall be required for all developments. This requirement may be waived for isolated developments under one-half acre where there will be no critical drainage problem created by the additional runoff from the proposed development. The NPDES program may require on-site retention for parcels less than one-half acre.

B. On-site stormwater retention areas shall be adequate to contain the volume of water required by the latest edition of the City of Phoenix Stormwater Policies and Standards Manual in effect at the time of the first submittal of plans to the Planning and Development Department.

All developments shall not increase the 100-year two-hour peak runoff, change the time of the peak, nor increase the total runoff from its pre-development values. (Ord. No. G-1641, § 2; Ord. No. G-2786, § 7; Ord. No. G-3313, § 1; Ord. No. G-3887, § 1; Ord. No. G-3994, § 1, 1997; Ord. No. G-5590, § 1, 2011; Ord. No. G-5707, 2012)