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• When the ponds are removed, the affected land will be regraded and revegetated pursuant to the CDMG's regulations, Section 4.05.17 and the approved WFC Reclamation Plan. 4) Pond 008 through 013 Designs Tables 2.05.3(3)-1 and 2.05.3(3)-2 list the values of CN and "k" for different soil and vegetation types at the New Horizon Mine. The tables have been revised to address new soils found in the amendment area. The curve number (CN) and "k" factor for each of the ponds is determined as a weighted average. The undisturbed area curve number and "k"factor information is based on the soils and vegetation information found within Sections 2.04.9 and 2.04.10, respectively, of the New Horizon mine permit application. The pond volumes are calculated by first using the Curve Number and Runoff Routine within the Hydrology module of the SURVCADD software and then using the USLE sediment storage routine within the Hydrology module of the SURVCADD 2000 software. The LS factors for the USLE are determined from the 3D CAD grid model of the drainage areas for each pond. The water volume • is determined from the weighted average CN for the watershed based on the worst case conditions over the life of the mine and the appropriate design storm rainfall. Curve numbers used are from 78 to 90 based on the existing conditions, level of disturbance and the hydrologic soil type of each watershed. Once the required volume of sediment and storm inflow is known, these two are combined to get the total required volume. SURVCADD was then used to design ponds in each location which had the parameters described in the previous section. All ponds were designed to contain the 25 year 24 hour event except Pond 010, which was designed to safely pass the 25 year event through the emergency spillway. Shown on the following two pages are the calculations used by the SURVCADD Program in determining the pond volumes. • (Revised 12/01) Attachment 2.05.3(3) -10-5