(A) Stormwater drainage systems.
The subdivider shall provide a surface water drainage system constructed to the standards of the North Carolina Department of Transportation, subject to the approval of the Planning Board.
(1) No surface water shall be channeled or directed into a sanitary drainage system.
(2) Where feasible, the subdivider shall connect to an existing storm drainage system.
(3) Where an existing storm drainage system cannot be feasibly extended to the subdivision, a surface drainage system shall be designed to protect the proposed development from water damage.
(4) Surface drainage course shall have side slopes of at least 3 feet of horizontal distance for each 1 foot of vertical distance, and courses shall be of sufficient size to accommodate the drainage area without flooding, and designed to comply with the standards and specifications for erosion control of the North Carolina Sedimentation Pollution Control Act.
(5) The minimum grade along the bottom of a surface drainage course shall be a vertical fall of at least 1 foot in each 200 feet of horizontal distance.
(6) Stream banks and channels downstream from any land disturbing activity shall be protected from increased velocity of runoff from the land disturbing activity in accordance with the North Carolina Sedimentation Pollution Control Act.
(7) Anyone constructing a dam or impoundment within the subdivision must comply with the North Carolina Dam Safety Law.
(8) In all areas of special flood hazards, all subdivision proposals shall have adequate drainage provided to reduce exposure to flood damage.
(B) Stormwater plans.
(1) For those subdivisions that involve more than 1 acre of land disturbance work for the construction of roads and other improvements, the application and approval process for the North Carolina Division of Water Quality shall be considered the stormwater management plan of record for Dare County. A copy of the approved stormwater management plan prepared by the developer and the permit issued by the State of North Carolina shall be submitted with the preliminary plat submitted for review to the Dare County Planning Board.
(2) For those divisions that involve less than 1 acre of land disturbance work for the construction of roads and other improvements, a detailed stormwater management and drainage plan shall be provided at the time of preliminary plat submission to the Dare County Planning Board. Such plans shall contain the following information:
(a) Total area of the site and proposed impervious coverage of proposed roads, parking areas, and other amenities to be developed.
(b) Total amount of land disturbing activity stated in square feet.
(c) A table that lists the maximum amount of lot coverage in square feet allowed on each proposed lot according to the applicable zoning standard.
(d) Typical cross-sections of roadside swales including the minimum side slopes.
(e) Size and materials of any culverts or piping to be used in the division. Any proposed retention basins or other drainage improvements.
(f) Other information pertaining to the items listed above that may be requested by the County Engineer or Dare County Planning Board.
(C) Stormwater standards.
(1) All roadside swales shall be established as retention areas and shall be shaped and stabilized with grass or sod at time final plat approval is requested from the Dare County Planning Board. Swales designed for the conveyance of stormwater shall be approved by the County Engineer prior to construction.
(2) Proposed subdivisions must maintain a minimum 30-foot wide setback area between all road improvements and these surface waters of Dare County: the Atlantic Ocean, Pamlico Sound, Roanoke Sound, Currituck Sound, Albemarle Sound, Croatan Sound, Alligator River, East Lake, South Lake, Stumpy Point Bay, Broad Creek, Sandy Bay, Shallowbag Bay, Kitty Hawk Bay, Buzzard Bay and any natural tributaries and bays of these waters.
(3) Driveway culverts or driveway slope areas shall be maintained by individual property owners or the homeowners association.
(4) No homeowner/lot owner/developer/ contractor/ shall be allowed to fill in, alter, or pipe any roadside swales shown on the drainage plan approved in conjunction with the final subdivision plat. Violation of this provision shall be a misdemeanor under G.S. § 14-4 and each day's continuing violation shall be a separate offense. Notwithstanding the criminal penalties, the county may institute a civil action against the offender, seek enforcement by appropriate equitable remedy, injunction and order of abatement or by any remedy authorized by G.S. § 160A-175. Restoration of the drainage improvements to the original status shall also be required.
(5) Amendments or changes to the drainage improvements after final plat recordation may be approved by the County Engineer if the County Engineer determines that such changes will not impact the entire drainage system for the division or any public road improvements.
(6) Each of the lots in the subdivision shall be limited to the amount of lot coverage of the applicable zoning district.
(7) A letter of certification from the engineer or designer of the stormwater improvements shall be submitted with the final plat certifying that all stormwater improvements have been installed as approved during preliminary subdivision plat review.
(8) Language shall be included on the preliminary plat, final plat, and in the homeowners covenants as follows:
(a) The maximum amount of lot coverage per lot shall not exceed the allowable square footage as indicated on the approved stormwater plan for this division. Lot coverage shall be as defined in Section 22-2 of the Dare County Zoning Ordinance.
(b) Driveway culverts shall be installed according to the standards of the Dare County Zoning Ordinance and in accordance with the stormwater plans approved in conjunction with this division. Driveway improvements may be sloped to retain the shape of the retention basins in lieu of driveway culverts if approved by the Dare County Engineer.
(9) Where any proposed driveway, roadway, walkway, or other improvement crosses an established drainage feature such as, but not limited to, roadside ditches, swales, streams or others, a culvert pipe shall be installed in order to maintain the anticipated flow of water through the drainage feature or to allow leveling of the retained volume. The following minimum standards for culverts shall apply:
(a) Culvert pipes shall be constructed using HDPE plastic pipe, concrete pipe, or other materials approved by the NC Department of Transportation. A list of approved culvert materials is available by contacting the NCDOT District Engineers office.
(b) All culvert pipe shall be a minimum of 15 inches in diameter. The pipe shall be of a sufficient length so that the graded side-slopes from the top of the driveway roadway, or walkway, to the top of the pipe are no steeper than 1 vertical foot to 3 horizontal feet (1:3). Larger pipe sizes may be required depending upon the size of the drainage feature or based upon the anticipated stormwater flows.
(c) Culverts shall be installed so that the bottom of the pipe is slightly bedded into the maintained bottom of the ditch or swale. An adequate driveway or roadway cover shall be installed above the culvert in order to prevent damage to the pipe. The minimum depth of cover based on the intended use of the crossing shall be as recommended by the pipe manufacturer.
(d) Culvert pipe shall be protected from erosion through the installation of vegetation, stone rip rap, or other commonly accepted erosion control measures.
(e) The property owner shall be responsible for maintenance and repair of driveway culverts. This includes the removal of sediment material that may build up at the ends of the culvert pipe or any other debris that interferes with the normal function of the culvert piping.
(10) Subdivision roads that feature culvert piping as part of an approved stormwater management plan shall be installed to the design standards of the NC Department of Transportation for subdivision entrance roads including type of materials proposed for use and dimensional requirements for the culvert piping. (See NCDOT manuals NC Standards and Specifications for Roads and Structures and Guidelines for Drainage Studies and Hydraulic Design.)
(11) The final plat for any division shall include language and/or a table that depicts the amount of lot coverage/impervious area coverage authorized by the State.
(Prior Code, § 153.34) (Ord. passed 11-29-1982)