Laserfiche WebLink
• information found within Sections 2.04.9 and 2.04.10, respectively, of the New Horizon mine permit <br />application. <br />The pond volumes are calculated by first using the Curve Number and Runoff Routine within the <br />Hydrology module of the SURVCADD software and then using the USLE sediment storage routine <br />within the Hydrology module of the SURVCADD 2000 software. The LS factors for the USLE are <br />determined from the 3D CAD grid model of the drainage areas for each pond. The water volume is <br />determined from the weighted average CN for the watershed based on the worst case conditions <br />over the life of the mine and the appropriate design storm rainfall. Curve numbers used are from 78 <br />to 90 based on the existing conditions, level of disturbance and the hydrologic soil type of each <br />watershed. Once the required volume of sediment and storm inflow is known, these two are <br />combined to get the total required volume. SURVCADD was then used to design ponds in each <br />location which had the parameters described in the previous section. All ponds were designed to <br />contain the 25 year 24 hour event except Pond 010, which was designed to safely pass the 25 year <br />event through the emergency spillway. <br />Shown on the following two pages are the calculations used by the SURVCADD Program in <br />determining the pond volumes. <br /> <br />2.05.3(3) -16 <br />• <br />