§ 24-147. General standards.

All development and redevelopment to which this article applies shall implement stormwater control measures that comply with each of the following standards:

(a)

Required for all development or redevelopment which disturbs one acre or more of ground area.

(b)

Stormwater treatment.

(1)

All stormwater treatment measures shall treat either:

a.

The runoff volume from the disturbed area calculated utilizing the one-year, one-hour design storm rainfall depth; or

b.

The difference in stormwater runoff volume between the pre- and post-development conditions for the one-year, 24-hour storm; whichever is greater.

(2)

Runoff volume drawdown time shall be a minimum of 48 hours, but not more than 120 hours.

(3)

All structural stormwater treatment systems used shall be designed to have a minimum of 85 percent average annual removal for total suspended solids (TSS).

(c)

Stormwater quantity control. Discharge stormwater at a rate equal to or less than the pre-development discharge rate for both the two-year, 24-hour storm and the ten-year, 24-hour storm with the ability to pass the 25-year, 24-hour storm.

(d)

General engineering design criteria for all projects shall be in accordance with 15A NCAC 2H .1008(c), as explained in the design manual.

(e)

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. Every structural BMP installed pursuant to this section shall be made accesible for adequate maintenance and repair by a maintenance easement. The easement shall be recorded and it's term shall specify who may make use of the easement and for what purposes.

(f)

For best management practices that require a separation from the seasonal high water table, provide separation by at least 12 inches of naturally occurring soil above the seasonal high water table.

(Ord. No. 11-0419, § 2, 4-7-11; Ord. No. 15-1064, § 1, 10-1-15)