15A NCAC 02H .1019      COASTAL COUNTIES

The purpose of this Rule is to protect surface waters in the 20 Coastal Counties from the impact of stormwater runoff from new development.

(1)           Implementing Authority. This Rule shall be implemented by:

(a)           local governments and other entities within the 20 Coastal Counties that are required to implement a Post-Construction program as a condition of their NPDES permits;

(b)           local governments and state agencies that are delegated to implement a stormwater program pursuant to G.S. 143-214.7(c) and (d); and

(c)           the Division in all other areas where this Rule applies.

(2)           APPLICABILITY OF THIS RULE. This Rule shall apply to the following types of developments within the Coastal Counties:

(a)           projects that require an Erosion and Sedimentation Control Plan pursuant to G.S. 113A-57;

(b)           projects that require a Coastal Area Management Act (CAMA) Major Development Permit pursuant to G.S. 113A-118; and

(c)           projects that do not require either an Erosion and Sedimentation Control Plan or a CAMA Major Development Permit, but meet one of the following criteria:

(i)            nonresidential projects that propose to cumulatively add 10,000 square feet or more of built-upon area; or

(ii)           residential projects that are within ½ mile of and draining to SA waters, and propose to cumulatively add more than 10,000 square feet of built-upon area, and result in a percentage built-upon area greater than 12 percent.

(3)           EFFECTIVE DATES. The effective dates are as follows:

(a)           for prior Rule .1000 of this Section, January 1, 1988;

(b)           for prior Rule .1005 of this Section, September 1, 1995;

(c)           for S.L. 2006-264, August 16, 2006; and

(d)           for S.L. 2008-211, October 1, 2008.

Prior versions of these rules are available for no cost on the Division's website at http://deq.nc.gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-permits/stormwater-program.

(4)           GENERAL REQUIREMENTS FOR ALL PROJECTS. In addition to the requirements of this Rule, development projects shall also comply with the requirements set forth in Rule .1003 of this Section.

(5)           DETERMINATION OF WHICH COASTAL STORMWATER PROGRAM APPLIES.

(a)           SA WATER. SA Water requirements shall apply to projects located within one-half mile of and draining to waters classified as SA-HQW or SA-ORW per 15A NCAC 02B .0301.

(i)            The SA boundary shall be measured from either the landward limit of the top of bank or the normal high water level. In cases where a water is listed on the Schedule of Classifications, but the applicant provides documentation from the Division of Water Resources or the U.S. Army Corps of Engineers that the water is not present on the ground, the applicant shall not be subject to the SA requirements of this Rule.

(ii)           An SCM with any portion of its drainage area located within the SA waters boundary shall be designed to meet SA water requirements.

(b)           FRESHWATER ORW. Freshwater ORW requirements shall apply to projects that drain to waters classified as B-ORW and C-ORW per 15A NCAC 02B .0301.

(c)           OTHER COASTAL COUNTY WATER. If a project does not meet the applicability requirements for Sub-Items (5)(a) or (b) of this Rule, then it shall be subject to the other Coastal County Water requirements set forth in Item (6) of this Rule.

(d)           PROJECTS THAT ARE SUBJECT TO TWO OR MORE COASTAL STORMWATER PROGRAMS. Projects with portions that are located within two or more coastal stormwater program boundaries shall meet the applicable requirements of Item (6) inside each of the project's portions.

(6)           STORMWATER REQUIREMENTS. Depending on the applicable program pursuant to Item (5) of this Rule, the following stormwater requirements shall apply:

(a)           SUMMARY OF COASTAL PROGRAM REQUIREMENTS. The requirements shall be in accordance with the following table:

Program that Applies	Maximum BUA for Low Density	Required Storm Depth for High Density Projects	Additional Special Provisions
SA Water	12%	One-year, 24-hour storm	SCMs for High Density SA Projects per Item (7) of this Rule; and the percentage built-upon area shall not exceed 25 percent within 575 feet of an SA-ORW
Freshwater ORW	12%	1.5 inch storm	None
Other Coastal County Water	24%	1.5 inch storm	None

(b)           VEGETATED SETBACKS. For all subject projects within the Coastal Counties, vegetated setbacks from perennial waterbodies, perennial streams, and intermittent streams shall be at least 50 feet in width for new development and at least 30 feet in width for redevelopment and shall comply with Rule .1003(4) of this Section.

(7)           SCMS FOR SA WATER HIGH DENSITY PROJECTS REQUIREMENTS. High density projects subject to SA water requirements shall use one of the following approaches for treating and discharging stormwater:

(a)           RUNOFF VOLUME MATCH. The project shall achieve runoff volume match, and excess runoff volume shall be released at a non-erosive velocity at the edge of the vegetated setback or to an existing stormwater drainage system.

(b)           RUNOFF TREATMENT WITH NON-DISCHARGING SCMs. SCM(s) shall provide runoff treatment without discharging in excess of the pre-development conditions during the one-year, 24-hour storm event. The runoff volume in excess of the one-year, 24-hour runoff volume shall be released at a non-erosive velocity at the edge of the vegetated setback or to an existing stormwater drainage system.

(c)           RUNOFF TREATMENT WITH DISCHARGING SCMs. SCM(s) shall provide runoff treatment for the difference between the pre- and post-development runoff volumes for the one-year, 24-hour storm event and meet the following requirements:

(i)            documentation shall be provided that it is not feasible to meet the MDC for infiltrations systems as set forth in Rule .1051 of this Section;

(ii)           the stormwater shall be filtered through a minimum of 18 inches of sand prior to discharge;

(iii)          the discharge from the SCM shall be directed to either a level spreader-filter strip designed as set forth in Rule .1059 of this Section, a swale that fans out at natural grade, or a natural wetland that does not contain a conveyance to SA waters; and

(iv)          the runoff volume in excess of the one-year, 24-hour storm event shall be released at a non-erosive velocity at the edge of the vegetated setback or to an existing stormwater drainage system.

History Note:        Authority G.S. 143-214.1; 143-214.5; 143-215.3(a)(1); S.L. 2008-211; S.L. 2017-211;

Eff. January 1, 2017 (portions of this rule previously codified in 15A NCAC 02H .1005);

Amended Eff. June 1, 2018.