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• of the tributary channel is in between the dam and the structures. See Map 2.05.3(3)-14 for <br />details. Water will flow in the channel first and since the maximum flow is only 11.5 acre feet <br />for a full dam break, it is not enough to cause the water to exceed the channel and flow uphill <br />to the Enstrom structures. Once the water goes downstream in the tributary channel, it <br />enters Tuttle Draw a short distance downstream and there are no structures that could be <br />affected by a small volume in Tuttle Draw since it is large enough to handle substantial peak <br />flows, as shown on Map 2.05.3(3)-1. For these reasons, Pond 011 is given a Class A <br />designation. <br />Pond 013 - As seen on Map 2.05.3(3)-1 Surface Hydrology, Pond 013 is located immediately <br />outside the floodplain of Tuttle Draw. Any dam break of this pond would discharge water <br />directly into Tuttle Draw. There is no chance the water could harm anything or anyone at <br />other locations. There are no structures that could be affected by a small volume in Tuttle <br />Draw since it is large enough to handle substantial peak flows, as shown on Map 2.05.3(3)-1. <br />For these reasons, Pond 013 is given a Class A designation. <br />7. Pond 008 through 014 Designs <br />• As shown above for Sediment Pond 007, Tables 2.05.3(3)-1 and 2.05.3(3)-2 list the values of <br />CN and "k" for different soil and vegetation types at the New Horizon Mine. The tables have <br />been revised to address new soils found in the area west of 27.00 Rd <br />The curve number (CN) and "k" factor for each of the ponds is determined as a weighted <br />average. The undisturbed area curve number and "k" factor information is based on the <br />soils and vegetation information found within Sections 2.04.9 and 2.04.10, respectively, of <br />the New Horizon mine permit application. <br />The pond volumes are calculated by first using the Curve Number and Runoff Routine within <br />the Hydrology module of the SURVCADD software and then using the USLE sediment <br />storage routine within the Hydrology module of the SURVCADD 2000 software. The LS <br />factors for the USLE are determined from the 3D CAD grid model of the drainage areas for <br />each pond. The water volume is determined from the weighted average CN for the <br />watershed based on the worst case conditions over the life of the mine and the appropriate <br />design storm rainfall. Curve numbers used are from 78 to 90 based on the existing <br />conditions, level of disturbance and the hydrologic soil type of each watershed. Once the <br />• required volume of sediment and storm inflow is known, these two are combined to get the <br />(Revised Juty Z(106) 2.05.3(3)-22 <br />