Orange County NC Website
3 <br />It should be noted in 2014 the State Legislature adopted a temporary rule eliminating <br />certain types of gravel from being classified as an impervious surface. This rule, <br />however, was rescinded resulting in all forms of gravel being considered an impervious <br />surface and calculated as same. <br />STATE ALLOWANCES: The State has produced a stormwater manual, denoting <br />required design elements, which can be viewed at: http: / /portal.ncdenr.org /web /ir /bmp- <br />manual. Property owners proposing a certain level of disturbance are required to <br />comply with established stormwater provisions as detailed within the UDO. <br />In certain circumstances the State allows the installation of a stormwater feature, <br />commonly referred to as a Best Management Practice (BMP), providing an opportunity <br />for the installation of additional impervious surface area. As of the writing of this <br />memorandum, the State recognizes only one BMP option allowing for additional <br />impervious surface allocation, specifically: <br />Permeable pavement - allows stormwater to infiltrate through void spaces <br />for temporary storage and, ultimately, to be infiltrated into the soil. The <br />total amount of additional impervious surface allotment is based on the <br />soil type. <br />Viability of permeable pavement is determined on a case by case basis <br />with no guarantee(s). <br />According to the manual, permeable pavement has the following general <br />advantages and disadvantages: <br />Advantages: <br />• Replaces built upon area with <br />materials that allow for infiltration <br />of stormwater. <br />• Eliminates standing water on <br />pavement. <br />• Helps to reduce pollutant runoff <br />concerns from a parcel of <br />property. <br />Disadvantages <br />• Without proper maintenance it <br />can become clogged by <br />sediment, compromising its <br />effectiveness. <br />• Not applicable for all site <br />conditions. <br />• Higher costs (i.e. installation <br />and perpetual maintenance) <br />County regulations, as contained in Section(s) 4.2.5 and 4.2.6 of the UDO, prohibit the <br />use of BMPs as satisfying, or allowing for an increase in allowable, impervious surface <br />area. <br />UPDATE: Staff would like to offer the following: <br />1. Members of the Planning Department and Erosion Control / Stormwater are <br />scheduled to review various elements of the existing stormwater program and <br />possible use of BMPs to allow for additional impervious surface area with State <br />officials on February 25, 2015. <br />2. Staff is developing potential amendment(s) to existing regulations requiring <br />developers to address the comprehensive impact of development with respect to <br />impervious surface limits and stormwater management. <br />