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under different operators since the turn of the century. As a <br /> consequence, a large percentage of affected acreages at the site <br /> were inherited, and had already attained maximum anticipated dis- <br /> turbance prior to 1960. Total affected acreage at the Silverton <br /> site was increased by Standard Metals operation, however, due to <br /> upgrading and expansion of existing mine and mill facilities. A7',- <br /> bandoned mill tailings disposal sites were reactivated and tailings <br /> deposition continued on these sites until capacity was reached. In <br /> 1976, mill tailings deposition commenced on a new disposal site, <br /> Tailings Pond No. 4, and tailings disposal is continuing on this <br /> site today. <br /> The mining permit issued for the Silverton operation listed <br /> 140 acres as the total affected acreage for which reclamation <br /> surety had been arranged. Acreaged affected by the operation <br /> over the past five years which are currently listed or in addition <br /> to permitted lands are listed below. For location of affected <br /> acreages at the site refer to Map /. <br /> 1978 <br /> 1.2 acres of moderately disturbed lands were created at the <br /> American Tunnel Portal . Affected acreage resulted from a borrow <br /> area used for constructing sedimentation basins. <br /> Tailings Pond No. 4 increased in size by 2.5 acres bringing <br /> total disturbance at the site to 18.5 acres. This was a planned <br /> disturbance within permit boundaries. <br /> Diversion ditches were constructed above all tailings deposi- <br /> tion sites to capture and divert upland drainage around tailing <br /> disposal sites. A total of 4 acres was disturbed by this activity <br /> and the disturbance was not outside permitted boundaries . <br /> Page 4 <br />