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Mine Waste Dump <br /> Page 2 <br /> Site Loading Estimate <br /> Based on limited information, the site loading estimate for this project site is based on: <br /> Adits- <br /> Using available data, zinc loading was calculated based on the average flow and average zinc <br /> values. <br /> Mine Waste Dumps and Tailings Piles- <br /> Site composite soil samples were tested using a water bath extraction. This test consists of <br /> exposing a 1:1 ratio by weight of material to deionized water. The mixture is briefly mixed then <br /> allowed to set for 30 minutes. The sample was then filtered ( 0.45 micron) and analyzed for metals. <br /> Annualized loading was calculated using rainfall data(proportionally adjusted for site elevation <br /> between the Silverton and Red Mountain weather stations), exposed area of waste dump or tailings <br /> site and loading based on 1:1 water bath test results. For comparison to adit flow loadings projects, <br /> the annualized loading was converted to an average daily loading. <br /> Based on these assumptions and procedures, SGC estimates that the average daily loading for this <br /> site may be as much as 8.0 pounds of dissolved zinc per day. SGC is under no obligation to defend <br /> these estimates and they should only be used as an estimate. SGC does not represent that its <br /> mitigation project at this site will remove any specific percentage of metals loading from this site: the <br /> loading estimate contained herein does not form the basis of an enforceable permit obligation. <br /> Description of Project <br /> The initial reclamation plan for the waste dump was to regrade the dump, cover with soil and <br /> plant. Due to underlying tailings, SGC believes that it is best to remove the tailings to a more stable <br /> environment and therefore proposes to move the tailings and the waste dump material required to <br /> access the tailings to Tailings Pond#4 for consolidation. This has been the procedure to date; as of <br /> the end of 1995, a total of 90,200 cubic yards had been shipped. The material was pH adjusted to <br /> near neutral by lime addition at the pond. The material is similar in acid base potential and metal <br /> content with the tailings pond material. <br /> All tailings encountered during excavation were removed,the waste dump remaining after tailings <br /> removal was feathered in to match the existing county road, the slopes were capped with a minimum <br /> of 16" of soil, the flat area was amended for direct revegetation, planted and mulched. Upland <br /> diversions will be improved to ensure that surface water flows are diverted away from the remaining <br /> material. Initial work on the waste dump removal project was started in 1994 as part of permitted <br /> work under SGC's MLR permit and SGC's stormwater permit. SGC considers the removal of tailings <br /> pile material to be authorized under the currently existing MLR permit. <br /> Removal of the tailings pile portion of this project was scheduled for 1995. In 1995, 57,000 cubic <br /> yards were hauled,for a project total 90,200 cubic yards, to Tailings Pond #4 at the Mayflower Mill. <br /> The removal portion of this project is complete. The salvaged soils were spread over the hill side, <br /> limestone was added to neutralize the soil and the area was seeded and mulched according to SGC's <br /> MLR Permit reclamation plan. <br />