To meet the requirements of the Town of Cary NPDES Phase II Permit any new development or redevelopment as of July 1, 2005, not exempted pursuant to Section 7.3.2(B) must meet either the low density or high density option requirements described below and in the Neuse Rules. New development or redevelopment in the Swift Creek or Jordan Lake Watersheds must meet the requirements of Section 4.4.6 of the LDO. For purposes of this Section 7.3.3, impervious surface area shall be calculated pursuant to Section 4.4.6(D)(2) of the LDO and the provisions of Section 4.4.6(G) of the LDO shall apply to all engineered stormwater control measures.
(A) Low Density Projects, having no more than two (2) dwelling units per acre or no more than twenty-four (24) percent impervious surface area for all residential and non-residential development, shall transport stormwater runoff by vegetated conveyances to the maximum extent practicable.
(B) High Density Projects, having more than two (2) dwelling units per acre or more than twenty- four (24) percent impervious surface area for all residential and non-residential development, shall implement stormwater control measures that comply with each of the following standards:
(1) The stormwater control measures shall control and treat the difference between the pre-development and post-development conditions for the one (1) year twenty-four (24) hour storm. Runoff volume drawdown shall be a minimum of twenty-four (24) hours, but not more than one hundred twenty (120) hours.
(2) Stormwater control measures shall be designed to achieve a minimum of eighty-five (85) percent average annual removal for Total Suspended Solids (TSS).