(A) Development standards for low-density projects. Low-density projects (no more than two dwelling units per acre or 24% built-upon area for all residential and non-residential development) shall comply with each of the following standards:
(1) Stormwater conveyance. Stormwater runoff from the development shall be transported from the development by vegetated conveyances to the maximum extent practicable.
(2) Stream buffers. All built-upon area shall be at a minimum of 30 feet landward of all perennial and intermittent surface waters. A perennial or intermittent surface water shall be deemed present if the feature is approximately shown on either the most recent version of the soil survey map prepared by the Natural Resources Conservation Service of the United States Department of Agriculture (USDA) or the most recent version of the 1:24,000 scale (7.5 minute) quadrangle topographic maps prepared by the United States Geologic Survey (USGS). An exception to this requirement may be allowed when surface waters are not present in accordance with the provisions of 15A NCAC 2B .0233 (3)(a) or similar site-specific determination made using division-approved methodology.
(3) Density provision. A project with an overall density at or below the low-density thresholds, but containing areas with a density greater than the overall project density, may be considered low density as long as the project meets or exceeds the post-construction model practices for low-density projects and locates the higher density- in upland areas and away from surface waters and drainageways to the maximum extent practicable.
(4) Restrictions on property use. The approval of the stormwater permit shall require an enforceable restriction on property usage that runs with the land, such as recorded deed restrictions or protective covenants, to ensure that future development and redevelopment maintains the site consistent with the approved project plans.
(B) Development standards for high-density projects. High-density projects (any project that exceeds the low density thresholds for dwelling units per acre or built-upon area) shall implement structural stormwater management systems that comply with each of the following standards:
(1) Treatment volume. The measures shall be designed to control and treat the stormwater run-off generated by the one inch of rain;
(2) Drawdown time. Runoff volume drawdown time shall be a minimum of 48 hours, but not more than 120 hours;
(3) Post-development flows. Stormwater shall not leave the project site at a rate greater than the predevelopment discharge rate for the ten-year, 24-hour storm;
(4) Total suspended solids removal. All structural stormwater treatment systems used to meet the requirements of the program shall be designed to have a minimum of 85% average annual removal for Total Suspended Solids (TSS);
(5) General design criteria. General engineering design criteria for all projects shall be in accordance with 15A NCAC 2H -1008(c), as explained in the Design Manual;
(6) Stream buffers. All built-upon area shall be at a minimum of 30 feet landward of all perennial and intermittent surface waters. A surface water shall be deemed present if the feature is approximately shown on either the most recent version of the soil survey map prepared by the Natural Resources Conservation Service of the United States Department of Agriculture (USDA) or the most recent version of the 1:24,000 scale (7.5 minute) quadrangle topographic maps prepared by the United States Geologic Survey (USGS). An exception to this requirement may be allowed when surface waters are not present in accordance with the provisions of 15A NCAC 2B .0233 (3)(a) or similar site-specific determination made using division-approved methodology.
(7) Restrictions on property use. The approval of the stormwater permit shall require an enforceable restriction on property usage that runs with the land, such as recorded deed restrictions or protective covenants, to ensure that future development and redevelopment maintains the site consistent with the approved project plans.
(Ord. passed 6-12-12)