Unified Development Ordinance, 4th supplement, September 2017

Part 10A: Unified Development Ordinance City of Raleigh, North Carolina 9 – 11 Effective Date: September 01, 2013 Supp. No. 4 Article 9.2. ​​Stormwater Management | CHAPTER 9. ​NATURAL RESOURCE PROTECTION Sec. 9.2.2. Active Stormwater Control Measures Where the lot is part of a cluster unit development or townhouse development or planned development approved prior to May 1, 2001, the imputed acreage of the lot shall be calculated by combining the individual lot area with the pro rata lot portion of 85% of the common open space shown on recorded plats of the development. Notwithstanding the impervious surface limitations of this subsection, any lot with either an existing detached house used for single-unit living or an existing attached house used for two-unit living shall be entitled to a one-time 400 square foot increase of impervious surface area without providing the additional stormwater control measures required by this subsection. This one-time exemption shall only be allowed if the qualifying structure (i) existed prior to the application of this ordinance, and (ii) the qualifying structure exists when the one-time exemption is applied to the property. However, the exemption once used shall remain with the property even if the qualifying structure is later demolished, voluntarily or involuntarily, from the property. This exemption, if not used, shall be inapplicable if the qualifying structure is voluntarily demolished from the property. Editor’s Note: This ordinance was first applied on November 27, 2016. b. The impervious surface limitations in this subsection may be exceeded if: i. It is demonstrated to the City that (with or without measures) the post-development volume of stormwater leaving the site is equal to or less than the volume of stormwater for the zoning district maximum percentage of impervious surface coverage allowed under subsection a . during the 90th percentile storm. For lots where the existing impervious surface area already exceeds the zoning district maximum percentage of impervious surface coverage limitations listed in subsection a. above, the post- development volume must be equal to or less than the volume of stormwater for the 90th percentile storm for the existing conditions; or ii. It is demonstrated to the City that (with or without measures) the flood level difference between the pre-development and post- development conditions for the 2-, 10-, 25-, 50- and 100-year storm events is equal to or less than 0.04 foot rise. c. For any property owner installing any measure to comply with subsection b.1 or b.2 above, the following additional requirements shall apply: i. The property owner must submit an annual inspection report to the Stormwater Management Division of the Engineering Services Department. The inspection report shall contain all of the following: a) The name and address of the property owner; b) A statement that an inspection was made of all required stormwater control facilities and/or required open space area; c) The date of the inspection; d) A statement that all inspected stormwater control facilities and/or open space areas are performing properly and are in compliance with the approved stormwater control plan, the applicable maintenance manual required by Sec. 9.2.2.D.2 and the Raleigh Stormwater Management Manual. No sampling of pollutant loading is required as part of the inspection; e) Current photographs of the stormwater control facilities and/or open space areas; f) The original signature of the owner; g) All inspection reports shall be on forms supplied by the City beginning from the date of the as-built certification under Sec. 9.2.2.D.3 and each year thereafter on the anniversary date of the certification. ii. On lots with measures, prior to issuance of a building permit, or recordation of a subdivision plat, whichever first shall occur, the property owner shall deed an access easement and temporary construction easement to the benefit of the City of Raleigh. The easements shall be in the form of a deed that the property owner records in the County in which the property is located. A copy of this recorded deed shall be provided to the Development Services Department. B. Nitrogen Reduction 1. Requirement a. Any new or expansion of existing development, not in compliance with the stormwater control master plan approved for its drainage basin, may

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