§ 267. Stormwater Control Structures.

(a)

Developments located within WPA overlay districts that have been approved for the high density development option authorized in Section 180.9(i) shall comply with the requirements of this section.

(b)

All stormwater control structures shall be designed by either a North Carolina registered professional engineer or landscape architect, to the extent that the General Statutes, Chapter 89A, allow. Other stormwater systems shall be designed by a North Carolina registered professional with qualifications appropriate for the type of system required; these registered professionals are defined as professional engineers, landscape architects, to the extent that the General Statutes, Chapter 89A allow and land surveyors, to the extent that the design represents incidental drainage within a subdivision, as provided in General Statutes 89(C)-3(7).

(c)

All stormwater controls shall use wet detention ponds as a primary treatment system. Wet detention ponds shall be designed for specific pollutant removal according to modeling techniques approved by the North Carolina Division of Environmental Management. Specific requirements for these systems shall be in accordance with the following design criteria:

1.

Wet detention ponds shall be designed to remove eighty-five (85) percent of total suspended solids in the permanent pool and storage runoff from a one (1) inch rainfall from the site above the permanent pool;

2.

The designed runoff storage volume shall be above the permanent pool;

3.

The discharge rate from these systems following the one (1) inch rainfall design storm shall be such that the runoff does not draw down to the permanent pool level in less than two (2) days and that the pond is drawn down to the permanent pool level within at least five (5) days;

4.

The mean permanent pool depth shall be a minimum of three (3) feet;

5.

The inlet structure shall be designed to minimize turbulence using baffles or other appropriate design features;

6.

Vegetative filters shall be constructed for the overflow and discharge of all stormwater wet detention ponds and shall be at least thirty feet in length. The slope and width of the vegetative filter shall be determined so as to provide a non-erosive velocity of flow-through the filter for a ten-year, twenty-four-hour storm with a ten-year, one-hour intensity with a slope of five (5) percent or less. Vegetation in the filter shall be natural vegetation, grasses or artificially planted wetland vegetation appropriate for the site characteristics.

(d)

In addition to the vegetative filters required in subsection (c)6., all land areas outside of the pond shall be provided with a ground cover sufficient to restrain erosion within thirty (30) days after any land disturbance. Upon completion of the stormwater control structure, a permanent ground cover shall be established and maintained as part of the maintenance agreement described in Section 268(c).

(e)

A description of the area containing the stormwater control structure shall be prepared and filed, consistent with Section 269(i) and (j), as a separate deed with the Edgecombe County Register of Deeds along with any easements necessary for general access to the stormwater control structure. The deeded area shall include the detention pond, vegetative filters, all pipes and water control structures, berms, dikes, etc., and sufficient area to perform inspections, maintenance, repairs and reconstruction.

(f)

Qualifying areas of the stormwater control structure may be considered pervious when computing total built-upon area. However, if the structure is used to compute the percentage built-upon area for one (1) site, it shall not be used to compute the built-upon area for any other site or area.

(Ord. No. 93-9, § 1, 6-7-93; Ord. No. 01-13, § 1, 7-9-01)