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Mr. Michael Boulay August 17, 1998 Page 2 Column 1 shows the watershed designations as depicted on Exhibit 13-2, Sheet 2 of 2, Surface Water Control Plan. Column 2 represents the corresponding watershed junction, branch, structure, utilized in the SEDCAD design model. The acreages shown in column 3 correspond to the respective areas where topsoil would be salvaged within each watershed that are contained in Addendum 13-3-E. The topsoil salvaged was estimated using a curve number of 91. Finally, column 4 provides the maximum acreages to be disturbed within each watershed, as shown on Exhibit 20-2, Sheet 2 of 2, 5-YR. Disturbance Boundary. Under the existing worst-case disturbance scenario the pond watershed would have 296.5 acres at a stage of topsoil removed. The proposed maximum disturbance based on the revised disturbance boundary would only contain 291.2 acres total of potential topsoil removal. Therefore, if we removed all of the topsoil within the proposed disturbance boundary, approximately 5 less acres will be disturbed within the entire 948.4-acre pond 010 watershed than what the pond was designed for under the worst-case scenario. This scenario will never be achieved because of two main factors: 1. A large portion of the area contained within watershed 2 has been mined through and the pit has been backfilled and the spoil graded. This area would then be modeled using a curve number of approximately 86 and not 91. 2. SCC still has estimated disturbance areas above the final coal recovery lines. Topsoil will not be removed from these areas until final pit backfilling and highwall reduction are to take place. One other point to make is that the original disturbance boundary associated with the pond 010 design was much greater in acreage covered than what we are proposing with the revised boundary. For instance, the amount of potential disturbance within watersheds 9, 10, and 11 combined are roughly 51.0 acres less than what was accounted for in the pond model. These watershed areas are directly upstream from pond 010. Watersheds 3, 4, and 5 have 51.8 acres less of potential disturbance associated with them. The main reason for this difference was when SCC decided not to extend Haul Road B up the ridgeline that these watershed areas cover. Of course the watersheds mentioned above have been offset by the additional 103.7 acres of potential disturbance within watershed number 2. It should be noted though that this disturbance will have less of an impact on the pond, because of the greater distance away from the pond itself than the other watersheds. For the reasons described above, SCC believes the existing design for pond 010 and the worst-case disturbance associated with this design will not be met based on the revised disturbance boundary associated with MR12. This will remain to be the worst-case