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<br />Briefly, water is collected at the 7500' haulage level (Figure 1), treated with a flocculent and scale <br />inhibitor and pumped to the 8100' level. At the 8100' level a portion of the water is diverted for <br />use in rock drills. The remainder is pumped to the surface via the No. 2 Shaft for treatment with <br />sodium hydroxide and flocculant at the No. 1 Shaft surface treatment site prior to discharge at the <br />Lower Urad Reservoir. Amore detailed discussion of water treatment is found in Section 5.1 and <br />Appendix D of the Henderson Mine and Mill Environmental Protection Plan (TR-04; under <br />review and discussion by DMG). Figure 2 presents a general water treatment schematic for the <br />Mine. <br />2.2 Future Discharge from the Henderson Mine <br />As discussed in Section 2.1, the average discharge from the Mine is approximately 1000 gpm. <br />Development scenarios and plans for future production below the 7500' level through the year <br />2000 likely will increase this flow to approximately 1500 gpm as the zone of influence of <br />dewatering increases. Under this scenazio, the present location of the underground collection <br />system at the 7500' level likely will be moved and rearranged to accommodate lower level <br />development. However, the process of pumping to the surface and treatment will remain the <br />same. <br />2.3 Mine Closure <br />Although Mine closure under this alternate scenario (or any scenario) required by the DMG in <br />this TR will not eliminate the need for pumping-treatment-discharge of Mine waters, it will <br />minimize and delay the process. <br />If all activity including pumping and treatment of mine water were to cease immediately at the <br />Mine, the workings would begin filling with water from the previously discussed sources at an <br />estimated constant inflow rate of 1000 gpm. If left unattended, the collection and pumping <br />station at the 8100' level would flood within 4 to 8 years. Mine waters would be expected to <br />breach the haulage tunnel portal at elevation 8948' in the upper Williams Fork River watershed i^ <br />a period calculated by W.W. Wheeler and Associates, Inc. Water Resource Engineers to be <br />between 9 years and 17.5 years as discussed in the recently submitted groundwater TR (TR-OS). <br />Since initial drainage would occur from the tunnel, there would be 1374 feet of freeboard before <br />any discharge would occur from the shafts in the upper West Fork of Clear Creek. It should be <br />noted that the low end of the W.W. Wheeler estimate probably is overly conservative as it is <br />premised on there being no storage capacity in the country rock surrounding the Mine workings. <br />3 <br />