(A) In developing plans for residential, commercial or industrial subdivisions, individual lots in a development shall be required to obtain and comply with the town water quality approval letter, and the development, as a whole, shall be considered to be a single land-disturbing activity requiring a permit. Hydrologic parameters that reflect the ultimate subdivision development shall be used in all engineering calculations.
(B) If individual lots or sections in a development are being developed by different property owners, all land-disturbing activities related to the development shall be covered by the approved drainage plan for the development. Individual lot owners or developers shall sign a certificate of compliance that all activities on that lot will be carried out in accordance with the approved drainage plan for the subdivision.
(C) Subdivisions that were approved prior to the effective date of these regulations are exempt from these requirements. Development of new phases of existing subdivisions, which have not received preliminary plat approval and are not exempted in § 153.022, shall comply with the provisions of these regulations.
(D) For residential land-disturbing activities involving less than one acre of actual land disturbance, which are not part of a larger common plan of development or sale, the property owner shall submit a simplified stormwater management control plan meeting the requirements listed in Chapter 155, Appendix B, § 13.
(E) For commercial land-disturbing activities involving less than one acre of actual land disturbance, which are not part of a larger common plan of development or sale:
(1) If the development is greater than 5,000 square feet or is increasing impervious area by more than 10%, the project must meet the standard stormwater requirements;
(2) But if the development is less than 5,000 square feet and does not increase impervious area by 10%, then a simplified stormwater management control plan meeting the requirements listed in Chapter 155, Appendix B, § 13 must be submitted.
(3) The simplified plan shall show proposed and existing contours, direction of flow, and erosion control measures.
(F) For land-disturbing activities disturbing more than one acre, all of the requirements of a drainage plan apply.
(G) For land-disturbance activities that are 25 acres or greater and discharge the pollutant or pollutant(s) of concern to a water body on the most current South Carolina 303(d) List of Impaired Waters, the stormwater pollution prevention plans prepared by applicants for construction sites must contain a written quantitative and qualitative assessment, showing that the BMPs selected will control the construction and post-construction stormwater discharges so that the stormwater discharges will not cause or contribute to a violation of water quality standards. A copy of the 303(d) list can be obtained from Water Quality Division, Bureau of Water, SCDHEC.
(Ord. 07045, passed 8-14-07; Am. Ord. 13027, passed 6-11-13)