§ 155.501  WATERSHED PROTECTION.
   (A)   Authority.  The State Legislature has, in G.S. §§ 143-214.5, 160A-371 and 160A-381, delegated the responsibility and authority to local governmental units to establish water supply watershed protection programs, to regulate land use and development within water supply watersheds, and to adopt regulations designed to promote the public health, safety and general welfare of its citizenry.
   (B)   Intent.  The intent of this section is to provide, in the designated watershed area, a higher level of control from activities and situations that could degrade the quality of the water entering the Neuse River.
      (1)   Unless specifically exempt below, the provisions of this section shall apply to development within the Watershed Protection Overlay (-WP), as established in § 155.200(C)(2).
      (2)   These requirements shall not apply to development existing as of January 1, 2006 except as provided in § 155.719, and shall not apply to a single-family detached, zero lot line, alley-loaded or accessory dwelling units developed on an existing lot.
   (C)   Public health requirements.  No activity, situation, structure or land use shall be allowed within the -WP Overlay which poses a threat to water quality and the public health, safety, and welfare. Such conditions may arise from inadequate on-site sewage systems which utilize ground absorption; inadequate sedimentation and erosion control measures; the improper storage or disposal of junk, trash or other refuse within a buffer area; the absence or improper implementation of a spill containment plan for toxic and hazardous materials; the improper management of storm water runoff, or any other situation found to pose a threat to water quality.
   (D)   Permitted uses.  The following uses and activities are permitted provided such uses are also permitted in the underlying zoning district, and providing that the restrictions stated herein are met.
      (1)   Agriculture, subject to the provisions of the Food Security Act of 1985 and the Food, Agricultural, Conservation and Trade Act of 1990.
      (2)   Silviculture, using BMPs required to implement the provisions of the Forest Practices Guidelines Related to Water Quality.
      (3)   Residential development.
      (4)   Nonresidential uses, excluding discharging landfills and sludge application sites, mining and quarrying activities, and the storage of toxic and hazardous materials unless a spill containment plan is implemented.
   (E)   Density and impervious surface limitations.  For the purpose of calculating impervious surface area, total project area shall include total acreage in the parcel on which the project is to be developed.
      (1)   Single family detached, zero lot line, alley-loaded.  Unless approved under the terms of division (E)(4) below, single-family detached, zero lot line and alley-loaded dwelling units shall not exceed two dwelling units per acre or 36% of impervious surface area as defined on a project-by-project basis. No residential lot shall be less than 1/3 acre, except within an approved open space residential subdivision, which meets the standards established in Article 2.
      (2)   All other residential and nonresidential development.  Unless approved under the terms of division (E)(4) below, all other residential and nonresidential development shall not exceed 24% of impervious surface area on a project-by-project basis unless storm water quality mitigation structures are installed and maintained by the property owner.
      (3)   Vegetative swales and vegetative swale outlets.
         (a)   All residential development within the -WP Overlay requiring sediment and erosion control permits shall utilize a curb and gutter stormwater collection system when practicable. When a curb and gutter stormwater collection system is used, the system shall utilize vegetative swale outlets to mitigate point-source stormwater flow out of the system into downstream creeks, streams, and waterways when practicable. The following standards shall apply to the use of vegetative swale outlets:
            1.   The vegetative swale outlet shall be designed and constructed to accommodate the peak stormwater flow from the ten-year storm, and the velocity of the flow shall be non-erosive;
            2.   The side-slopes of the vegetative swale shall not be steeper than 5:1 (horizontal to vertical). When this is not practicable due to physical or topographic constraints, devices to slow the rate of stormwater flow and to encourage infiltration to reduce pollutant delivery shall be provided; and
            3.   The vegetative swale outlet shall be as wide and long as practicable under the circumstances to maximize the stormwater flow mitigation effect of the outlet.
         (b)   When the Town Council determines that a curb and gutter stormwater collection system is not the preferred means of controlling stormwater runoff, vegetative swales (with vegetative swale outlets) shall be utilized in lieu of a curb and gutter stormwater collection system when practicable. If site or development conditions do not favor the exclusive use of vegetative swales, hybrid stormwater drainage systems utilizing elements of vegetative swales and curb and gutter stormwater collection systems may be considered. The standards set out in division (a) above shall apply to the use of vegetative swale outlets, and the following standards shall apply to the use of vegetative swales in lieu of curb and gutter stormwater collection systems:
            1.   A vegetative swale shall be designed and constructed to provide for even distribution of stormwater runoff across the width of the swale;
            2.   The slope and length of a vegetative swale shall be designed, constructed, and maintained to provide a non-erosive velocity of stormwater flow through the swale for the ten-year storm and shall have a slope of 5% or less when practicable; and
            3.   A vegetative swale shall contain natural vegetation, grasses, or artificially planted wetland vegetation appropriate for the applicable site characteristics and proposed development.
         (c)   For purposes of this section, the characteristics of the site and proposed development shall be considered in determining the practicability of utilizing vegetative swales and vegetative swale outlets and the design characteristics thereof, including soil types and compaction, topography, roadway and driveway design, lot sizes, front lot-line distances, and the need for and availability of sidewalks and pedestrian facilities in the development.
         (d)   Alternative best management practices (BMPs) shall be considered by the town to satisfy the objectives of this section to provide safe and adequate pedestrian and road networks and facilities, control peak stormwater flow discharges, reduce total stormwater runoff volume, provide effective trapping and filtering of stormwater pollutants, and reduce the channelization and erosive velocity of stormwater runoff.
      (4)   Industrial (I-1, I-2) or Business (B-1, B-2, B-3) Districts.  In addition to the development allowed under divisions (E)(1) and (E)(2) above, new development and expansions to existing developments may be approved on a project-by-project basis with impervious surfaces not exceeding 70% of the new project area within 10% of the total regulated watershed protection area, when approved by the Council as a special intensity allocation (SIA). The Planning Director shall be responsible for maintaining necessary records of SIA approvals as required. Projects developed under the terms of this division shall minimize impervious areas when feasible, give full consideration to dimension of proposed and required riparian buffers, direct storm water away from surface waters when possible, and follow best management practices in design of measures to minimize negative water quality impacts.
   (F)   Open space subdivision.  Open space residential subdivisions (see §§ 155.200 through 155.204) are allowed in the -WP Overlay with the following requirements:
      (1)   Density or impervious surface limitations of the project shall not exceed division (E) above.
      (2)   All impervious surfaces shall be designed and located to minimize stormwater runoff impact to the receiving waters and minimize concentrated storm water flow.
   (G)   Changes and amendments.  The Town Council may, on its own motion or on petition, after public notice and hearing, amend, supplement, change, or modify these requirements. All applications for changes, supplements, amendments, or modifications of this section shall follow the procedures outlined in § 155.703. Under no circumstances shall the Town Council adopt such amendments, supplements, or changes that would cause this section to violate the Water Supply Watershed Protection Rules as adopted by the state. All amendments must be approved and filed with the state.
   (H)   Planning Director.
      (1)   (a)   The Planning Director shall monitor land use activities within the -WP Overlay to identify situations that may pose a threat to water quality.
         (b)   The Planning Director shall report all findings to any appropriate public agency or official and request recommendations and assistance.
         (c)   Where the Planning Director finds a threat to water quality and the public health, safety, and welfare, the Public Works Director shall institute any appropriate action in accordance with the provisions of § 10.99 of the Town Code of Ordinances.
      (2)   The Planning Director shall issue zoning compliance permits in the -WP Overlay. A record of all permits shall be kept on file and shall be available for public inspection during regular office hours.
      (3)   The Planning Director shall keep records of the town's use of the provision, which allows a maximum of 10% of the regulated area to be developed at a maximum of 70% impervious surface area. Records shall include the total areas of non-critical watershed area, total acres eligible to be developed at this option, and total acres approved for this development option. Individual records, which include location, type of use, number of developed acres and stormwater management plans, shall be kept for each project.
      (4)   The Planning Director shall keep records of all amendments to this section, and shall provide copies of all amendments upon adoption to the appropriate state agency.
      (5)   The Planning Director shall keep a record of variances to this section (see § 155.716(G)). This record shall be submitted to the appropriate state agency on an annual basis on or before January 1, and shall provide a description of each project receiving a variance and the reasons for granting the variance.
(Ord. 2005-11-02, passed 11-21-05; Am. Ord. 2006-02-02, passed 2-20-06; Am. Ord. 2007-05-04, passed 5-7-07 )