Orange County NC Website
Browse       Search
Orange County SE & SC Ordinance October 23 2007 <br />D. Design and Performance of Control Measures <br />1. Design Storm <br />Except as provided in Section 8(1))(2)(b) of this Ordinance and in the standard <br />for sediment ponds in the Soil Erosion and Sediment Control Manual erosion <br />and sedimentation control measures, structures, and devices shall be so planned, <br />designed, and constructed as to provide protection from accelerated erosion and <br />sedimentation from the calculated maximum peak rates of runoff from the ten - <br />year frequency storm. Runoff rates shall be calculated using the procedures in <br />the USDA Soil Conservation Service's "National Engineering Field Manual for <br />Conservation Practices," or other calculation procedures acceptable to the <br />Erosion Control Officer. <br />2. Standards for High Quality Waters <br />In High Quality Water (HQW) zones the following design standards shall apply: <br />a. Uncovered areas in HQW zones shall be limited at any time to a <br />maximum total area of 20 acres within the boundaries of the tract. <br />Only the portion of the land - disturbing activity within a HQW zone <br />shall be governed by this section. Larger areas may be uncovered <br />within the boundaries of the tract with the written approval of the <br />Director of the Division of Land Resources of the Department of <br />Environment, Health, and Natural Resources. <br />b. Erosion and sedimentation control measures, structures, and devices <br />within HQW zones shall be so planned, designed, and constructed <br />to provide protection from the runoff of the 25 -year storm which <br />produces the maximum peak rate of runoff. The peak rate of runoff <br />shall be calculated according to procedures in the United States <br />Department of Agriculture Soil Conservation Service's National <br />Engineering Field Manual for Conservation Practices or according <br />to procedures adopted by any other agency of this state or the <br />United States or any generally recognized organization or <br />association. <br />Sediment ponds (also called "sediment basins ") within HQW zones <br />shall be designed and constructed such that the pond will have a <br />settling efficiency of at least 70% for the 40 micron (0.04 mm) size <br />soil particle transported into the basin by the runoff of that 2 -year <br />storm which produces the maximum peak rate of runoff. The peak <br />rate of runoff shall be calculated according to procedures in the <br />United States Department of Agriculture Soil Conservation <br />Service's National Engineering Field Manual for Conservation <br />Practices or according to procedures adopted by any other agency <br />of this state or the United States or any generally recognized <br />organization or association. <br />15 <br />