15A NCAC 02B .0251 RANDLEMAN LAKE WATER SUPPLY WATERSHED: STORMWATER REQUIREMENTS
The following is the urban stormwater management strategy for the Randleman Lake watershed:
(1) All local governments that have land use authority within the Randleman Lake watershed shall comply with stormwater management requirements as outlined in this Rule. Although the management requirements for the upper and the lower portions of the watershed are similar, additional density-related stormwater requirements apply to the lower portion of this watershed that do not apply to the upper portion of the watershed. The upper portion of the watershed is defined as those waters and lands of the Deep River watershed which drain to the Oakdale-Cotton Mill Dam. The lower portion of the watershed are those waters and lands of the Deep River upstream and draining to the Randleman Lake Dam, from the Oakdale-Cotton Mill Dam to the Randleman Dam.
(2) To meet the requirements of this Rule, the local governments with jurisdictions in the upper portion of the Randleman Reservoir watershed shall meet the state’s rules for a WS-IV classification as specified in 15A NCAC 2B .0104, .0202 and .0216, the conditions specified in their existing ordinances, the riparian area protection requirements of Rule .0250 of this Section, along with the stormwater planning requirements set forth in Sub-Items (4), (5), and (6) of this Rule.
(3) To meet the requirements of this Rule, local governments with jurisdictions in the lower portion of the Randleman Lake watershed shall meet the provisions of Sub-Items (4), (5) and (6) of this Rule along with the following:
(a) Within 270 days of the effective date of this Rule, the affected jurisdictions, in coordination with the Piedmont Triad Regional Water Authority, shall submit local water supply ordinances to the Environmental Management Commission for approval. The ordinances shall at least meet the state’s minimum rules for a WS-IV classification as specified in 15A NCAC 2B .0104, .0202 and .0216, except that the requirements of this Sub-Item shall replace the nonpoint source requirements in 15A NCAC 2B .0216(3)(b) for the lower portion of the Randleman Lake watershed.
(b) The local ordinances shall provide for review and approval of stormwater management plans for new developments to ensure that the following conditions can be met:
(i) Stormwater pollution control criteria for the Randleman Lake watershed outside of critical area:
(A) Low Density Option: For each development project, development density must be limited to either no more than one dwelling unit per acre of single family detached residential development (or 40,000 square foot lot excluding roadway right-of-way) or 12 percent built-upon area for all other residential and non-residential development. Stormwater runoff shall be transported primarily by vegetated conveyances. Conveyance system shall not include a discrete stormwater collection system as defined in 15A NCAC 2B .0202;
(B) High Density Option: If new development exceeds the low density option requirements as stated in Sub-Item (2)(b)(i) of this Rule, then engineered stormwater controls must be used to control runoff from the first inch of rainfall. Engineering controls may consist of wet detention ponds designed in accordance with 15A NCAC 2H .1000 or alternative stormwater management systems consisting of other treatment options, or a combination of options, that are approved by the Director of the Division of Water Quality in accordance with 15A NCAC 2B .0104(g). New residential and non residential development shall not exceed 50 percent built-upon area, unless an alternative high density option is submitted to the Commission as part of the submittal of the local water supply watershed protection ordinance and determined by the Commission to provide equal or greater water quality protection in Randleman Reservoir and its tributaries;
(C) Cluster development shall be allowed on a project‑by‑project basis as follows:
(I) overall density of the project meets associated density or stormwater control requirements of this Section;
(II) buffers meet the minimum statewide water supply watershed protection requirements and those specified for the Randleman Lake watershed riparian areas in Rule .0250 of this Section;
(III) built‑upon areas are designed and located to minimize stormwater runoff impact to the receiving waters, minimize concentrated stormwater flow, maximize the use of sheet flow through vegetated areas, and maximize the flow length through vegetated areas;
(IV) areas of concentrated development are located in upland areas and away, to the maximum extent practicable, from surface waters and drainageways;
(V) remainder of tract to remain in vegetated or natural state by utilization of one of the methods provided in Sub-Item 3(b)(i)(C)(VI) of this Rule;
(VI) area in the vegetated or natural state may be conveyed to a property owners association; a local government for preservation as a park or greenway; a conservation organization; or placed in a permanent conservation or farmland preservation easement;
(VII) a maintenance agreement for the vegetated or natural area shall be filed with the Register of Deeds; and
(VIII) cluster development that meets the applicable low density option requirements shall transport stormwater runoff from the development by vegetated conveyances to the maximum extent practicable;
(D) If local governments choose the high density development option which requires engineered stormwater controls, then they shall assume ultimate responsibility for operation and maintenance of the required controls as outlined in Rule .0104 of this Subchapter;
(E) Impervious cover shall be minimized to the maximum extent practical through clustering, narrower and shorter paved areas (streets, driveways, sidewalks, cul-de-sacs, and parking lots), and spreading rooftop and other impervious area runoff over pervious areas. Land clearing during the construction process shall be limited to the maximum extent practical. The local government permit shall require recorded deed restrictions and protective covenants to ensure that development activities maintain the development consistent with the plans and specifications approved by the local governments;
(F) The project is in compliance with the riparian area protection requirements as specified in 15A NCAC 2B .0250 (Randleman Lake riparian area rule);
(G) No new development shall be allowed within 50 feet of waters affected by the Randleman riparian area rule 15A NCAC 2B .0250;
(H) New development meeting the high density option shall be located at least 100 feet from perennial waters as identified on topo or soil survey maps; however, within the area between 50 and 100 feet adjacent to the perennial water body, water dependent structures, or other structures, such as flag poles, signs and security lights, which result in only diminimus increases in impervious area and public projects such as road crossings and greenways may be allowed where no practicable alternative exists; these activities shall minimize built‑upon surface area, divert runoff away from surface waters and maximize the utilization of BMPs;
(I) For local governments that do not use the high density option, a maximum of 10 percent of each jurisdiction’s portion of the watershed outside of the critical area as delineated on April 1, 1999 may be developed with new development projects and expansions to existing development of up to 70 percent built-upon surface area in addition to the new development approved in compliance with the appropriate requirements of Sub-Item (3)(b)(ii)(A) of this Rule. For expansions to existing development, the existing built-upon surface area shall not be counted toward the allowed 70 percent built-upon surface area. A local government having jurisdiction within the watershed may transfer, in whole or in part, its right to the 10 percent/70 percent land area to local government within the watershed upon submittal of a joint resolution for review by the Commission. When the designated water supply watershed area is composed of public land, such as National Forest land, local governments may count the public land acreage within the designated watershed area outside of the critical area in figuring the acreage allowed under this provision. Each project shall, to the maximum extent practicable, minimize built-upon surface area, direct stormwater runoff away from surface waters and incorporate best management practices to minimize water quality impacts;
(ii) Stormwater pollution control criteria for critical areas of the watershed:
(A) Low Density Option: Development density must be limited to either no more than one dwelling unit per two acres of single family detached residential development (or 80,000 square foot lot excluding roadway right-of-way) or six percent built-upon area for all other residential and non-residential development. Stormwater runoff shall be transported primarily by vegetated conveyances to the maximum extent practicable;
(B) High Density Option: If new development exceeds the low density option requirements as stated in Sub-Item (3)(b)(ii) of this Rule, then engineered stormwater controls must be used to control runoff from the first inch of rainfall. New residential and non residential development shall not exceed 30 percent built-upon area;
(C) No new permitted sites for land application of residuals or petroleum contaminated soils shall be allowed;
(D) No new landfills shall be allowed; and
(E) Sub-Items (3)(b)(i)(C)-(H) of this Rule also apply to the critical area.
(4) Within 12 months of the effective date of adoption of this Rule, all local governments with jurisdictions in the Randleman Lake watershed shall develop comprehensive stormwater management plans and submit those plans to the Commission for review and approval. Comprehensive stormwater management plans meeting the criteria set forth in Subparts (4)(a) through (4)(f) of this Rule shall be approved. Within six months of the Commission’s approval of the local plan, subject local governments shall adopt and implement their approved plan. Those plans shall include, but not be limited to, the following:
(a) Evaluation of existing land use within Oak Hollow Lake subwatershed, High Point Lake subwatershed and Deep River 1 subwatershed in the Randleman Lake watershed with recommendations that show how overall built-upon area (for existing and future development) for each subwatershed can be minimized and high intensity land uses can be targeted away from surface waters and sensitive areas. Oak Hollow Lake subwatershed is defined as all land areas draining to Oak Hollow Lake. High Point Lake subwatershed is defined as all land areas draining to High Point Lake, East Fork Deep River and West Fork Deep River from Oak Hollow Lake Dam. Deep River 1 subwatershed is defined as all land areas draining to the Deep River from High Point Lake Dam to Freeman Mill Dam. This evaluation shall be done by the local governments having jurisdiction in those watersheds, working in cooperation with the PTRWA;
(b) Coordination between all affected jurisdictions to encourage their development in the existing urban areas. The planning effort shall include provisions for areas of contiguous open space to be protected through conservation easements or other long-term protection measures and provisions to direct infrastructure growth towards existing urban development corridors rather than to rural lands;
(c) Evaluation of existing ordinances, municipal programs (maintenance, street cleaning, etc.) and other local policies to identify opportunities for stormwater quality improvements including reducing the amount of built-upon area that is required for uses such as parking, building setbacks, road widths and cul-de-sacs. The evaluations shall consider development options such as multiple story buildings, mixed use to encourage pedestrian travel and mass transit and an identification of municipal activities and procedures that may be modified to allow for stormwater pollution prevention opportunities;
(d) Implementation of watershed protection public education programs;
(e) Identification and removal of illegal discharges; and
(f) Identification of suitable locations for potential stormwater retrofits (such as riparian areas) that could be funded by various sources.
(5) Local governments may submit a more stringent local stormwater management program plan. Local stormwater management programs and modifications to these programs shall be kept on file by the Division of Water Quality.
(6) If a local government fails to submit an acceptable local stormwater management program plan within the time frames established in this Rule or fails to properly implement an approved plan, then stormwater management requirements for existing and new urban areas within its jurisdiction shall be administered through the NPDES municipal stormwater permitting program per 15A NCAC 2H .0126 which shall include at a minimum:
(a) Subject local governments shall be required to develop and implement comprehensive stormwater management programs for both existing and new development.
(b) These stormwater management programs shall provide all components that are required of local government stormwater programs in this Rule.
(c) Local governments that are subject to an NPDES permit shall be covered by the permit for at least one permitting cycle (five years) before they are eligible to submit a revised local stormwater management component of their water supply watershed protection program for consideration and approval by the EMC.
History Note: Authority G.S. 143-214.1; 143-214.5; 143-214.7; 143-215.1; 143-215.3(a)(1);
Eff. April 1, 1999.