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File SL-01. Penni~ Nu. C81-010 Trapper Mining Inc. I I/?3/98 Page 6 using field estimates of the volumes of sediment that have accumulated in each of the ponds in those drainages. Bz¢~ard drainages -The Division estimated the volumes of sediment in the ponds in the Buzzard drainages on September 1, 1998 during the Division's regular monthly inspection (please refer to attached Appendix B). As shown in Table 3, the sediment volume estimates for the ponds in the Buzzard drainages appear to confirm that post- mining sediment yield in those drainages has been less than the LISLE-calculated pre- mining rates (as adjusted for sediment delivery). In addition, the estimates of pond sediment volumes translate into post-mining sediment yield rates that compare favorably with the LISLE-calculated post-mining soil loss rate. Coyote drainage -The Division's pacing and measuring stick survey methods used for the Buzzard ponds were not feasible for Trapper's largest pond, Coyote; therefore, the Division relies on the operator's annual surveys of that pond for an indication of the historical sedimentation rate in Coyote drainage (see attached Appendix C). Sediment was last cleaned out of Coyote pond in fall 1988. Trapper's annual sediment surveys have not detected additional sediment accttmulation in the pond since July 1991, 7 yeazs ago. Annual surveys consistently found 38 acre-feet of sediment in the pond. Trapper surveyed Coyote pond by shooting points in the pond when it was dry and probing from a rafr when it contained water. The pond was dry during most of the surveys. Trapper's surveys could reasonably be expected to have detected any new sediment thickness of 4 inches (0.33 foot) or more; therefore, the calculation in Table 3 assumed a layer of sediment 0.33-foot thick had accumulated in the pond. (A layer 0.33 foot thick distributed over the entire 6-acre area of the pond equates to 3223 cubic yards.) As shown in Table 3, Coyote's post-mining soil loss rate appeazs to have been less than the LISLE-calculated pre-mining rate and it compares favorably with the LISLE-calculated post-mining soil loss rate. Pond sediment volumes cannot be used for estimating post-mining sediment yield from the bond release blocks in No Name drainage because that drainage has not yet been fully reclaimed. Mining continues in the upper reaches of that drainage. Reclamation practices in No Name aze similaz to those in the Buzzazd and Coyote drainages; therefore, there is no reason to believe sediment yield rates in No Name would be significantly different from those drainages.