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Article 6: Development Standards 110 <br /> Section 6.15: Soil Erosion and Sedimentation Control245F <br /> (4)(e) Open Channels <br /> (i) Newly constructed open channels in HQW zones shall be <br /> planned, -designed,and constructed with side slopes no steeper <br /> than two 2) horizontal to one 1)vertical if a vegetative cover is <br /> used for stabilization <br /> (ii) Steeper slopes may be permitted if soil conditions permit a <br /> steeper slope or where the slopes are stabilized by using <br /> mechanical devices, structural devices or other acceptable <br /> devices. <br /> (iii) In any event, the angle for side slopes shall be sufficient to <br /> restrain accelerated erosion. <br /> W(f) Ground Cover <br /> (i) Ground cover sufficient to restrain erosion must be provided for <br /> any portion of a land--disturbing -activity in a HQW zone within <br /> the timelines as specified in the most current version of the North <br /> Carolina Administrative Code Title 15A Chapter 4: Sedimentation <br /> Control.294W th_in_7_days and/or 15 working days or 60 calonda <br /> days whichever period is shorter the timelines specified for <br /> HQWzones in the most o rrent -&ro 2$5 of the N( Frnsinn <br /> Control ' m following ompletion of construction or <br /> development <br /> (7) Standards for the Upper Neuse River Basin (Falls Lake Watershed)2s6 <br /> In the Upper Neuse River Basin (Falls Lake Watershed), in areas not classified as High <br /> Quality Water (HQW)zones, the following design standards shall apply: <br /> (a) Erosion and Sedimentation Controls <br /> (i) Erosion and sedimentation control measures, structures, and <br /> devices within HQW zones shall be so planned, designed, and <br /> constructed to provide protection from the stormwater runoff of <br /> the 25-year storm that produces the maximum peak rate of <br /> stormwater runoff. <br /> (i i) The peak rate of stormwater runoff shall be calculated according <br /> to procedures in the latest edition of the United States <br /> Department of Agriculture Natural Resources Soil Conservation <br /> Service's "National Engineering Field Manual Handbook 630 for <br /> Conservation Practices" or according to other calculation <br /> procedures acceptable to the Erosion Control Officer. <br /> (b) Sediment Ponds <br /> (i) Sediment ponds (also called "sediment basins") in the Upper <br /> Neuse River Basin (Falls Lake Watershed) shall be planned, <br /> designed, and constructed so that the basin will have a settling <br /> efficiency of at least 70 percent for the 40-micron size soil <br /> particle transported into the basin by the stormwater runoff of the <br /> 2-year storm that produces the maximum peak rate of <br /> stormwater runoff. <br /> (i i) The peak rate of stormwater runoff shall be calculated according <br /> 294 For ground cover requirements-consistent reference to"most current version" of the NC Administrative Code <br /> Title 15A Chapter 4: Sedimentation Control <br /> 296 New section added to specify additional requirements within the Falls Lake Watershed. <br /> Orange County, North Carolina—Unified Development Ordinance Page 6-127 <br />