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Based upon the latest two foot topography, the current volume of this pond is 4.4 acre-feet. <br />Design Volume Calculations Sediment Pond # 2 <br />Area Drainage Area (acres) 11.19 <br />Design Event 10 yr. storm <br />Design Precipitation 2.4 <br />Average CN 86 <br />Calculated S 1.62790697674 <br />Description Exposed loose soil some vegetation <br />Calculated Runoff Volume (Q) 1.16 <br />Calculated Runoff Volume (acre-ft.) 1.08 <br />Ponding Percentage 0.00 <br />Actual Runoff Volume (acre/ft.) 1.08 <br />Adding 0.4 ac-ft for sediment storage yields a total volume of 1.48 acre-feet needed in the pond <br />above the spillway. The pond has 4.4 acre feet, therefore, it is more than adequate. The pond will <br />actually contain the runoff for the 11.19 acre drainage area for the 100 yeaz 24 hour event, therefore, <br />no spillway is needed. A principal and emergency spillway are installed in the pond and past <br />calculations show that the pond will route large storms through the spillway structures while <br />providing detention time for sediment and greatly lowering the peak flows. <br />Once Phase II bond release is granted, this pond will be removed. <br />Collection Ditches and Channels <br />One collection ditch routes surface runoff to the sediment pond. The Nest Collection Ditch collects <br />surface drainage from the northwest segment of the haul road, and a small azea of the Permanently <br />Reclaimed Spoils Area and conveys the runoff to Sediment Pond No. 2. The culvert crossing for <br />this ditch under the access road is unchanged from the approved plan. After final bond release is <br />granted, this ditch and culvert will remain to provide drainage for the development site. <br />Designs for collection ditches and channels aze contained in Appendices 5-2, 5-9, and on Map 5-10. <br />All ditches were constructed to control the design flow and to minimize erosive velocities during <br />design event conditions. <br />TR09, TRll (v1.0) 5-10 Revised 3/98, 8/02 <br />