(A) Owners of property subject to this chapter and required to install structural stormwater control measures shall implement those measures in compliance with each of the following standards:
(1) The measures shall control and treat runoff from the first inch of rain.
(2) The design volume shall take into account the runoff at build out from all surfaces draining to the system.
(3) General engineering design criteria for all projects shall be in accordance with 15A NCAC 2H.1050-1062, as explained in the Design Manual.
(4) Vegetated side slopes shall be no steeper than 3:1.
(5) The measure shall discharge the storage volume at a rate equal or less than the pre-development discharge rate for the one-year, 24-hour storm.
(6) Overflow or bypass devices for inflow volumes in excess of the treatment volume or peak attenuation volume, if applicable, shall be included.
(7) Each point of discharge from the development must be evaluated for attenuation needs. The post development runoff rate for the one-year, two-year, ten-year and 25-year, 24-hour storm events must be equal or less than the pre-development rates for the equivalent storm events at each point of discharge.
(8) The approval of the stormwater permit shall require enforceable restrictions on property usage that runs with the land, including recorded deed restrictions and protective covenants, to ensure that future development and redevelopment maintains the site consistent with the approved project plans.
(B) The project shall meet either a nitrogen loading rate target of 3.6 pounds/acre/year or "runoff volume match". Proposed development projects that would replace or expand existing structures and result in a net increase in built-upon area shall meet one of these options for the project less any existing built-upon area.
(C) Proposed development undertaken by a local government solely as a public road expansion or public sidewalk project, or proposed development subject to the jurisdiction of the Surface Transportation Board, may meet the loading rate target of this item entirely through use of permanent nutrient offset credit pursuant to 15A NCAC 02B.0703.
(D) Where in satisfying the on-site requirements of division (A) of this section, a project does not meet the loading rate target of this section, it may do so through use of permanent nutrient offset credit pursuant to 15A NCAC 02B.0703. Persons doing so shall provide proof of credit acquisition to the town prior to issuance of the stormwater permit.
(Ord. 2020-11-01, passed 11-16-20)