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• The Packrat drift at 50% (i.e. it is 50% mineralized) of the baseline emission rate. <br />Approximately 50% of the drift passes through ore zones that were mined out by <br />historical mining operations; <br />• Future developmental drifts at 50% of the baseline emission rate. This is likely a <br />conservative (i.e., high) value as the purpose of the drifts are solely to reach ore <br />zones and they only encounter ore incidentally; and, <br />• Future ore zone stopes at 100% of the baseline emission rate. <br />The areas of the currently exposed ore zone and future drifts are based on measurement <br />from Figures 4 through 7. It is conservatively estimated that 87,000 square feet of ore <br />zone stopes may be open at any one time during mining. This is based on having 10 open <br />stopes each measuring 100 x 100 ft on average with 87% stope recovery. Current mining <br />plans call for only 8 stopes to be open at any one time. The areas of each zone and the <br />calculated prorated areas are summarized in Table 2. <br />Table 2 <br />Prorated Mining Areas <br /> <br /> <br />Area Description <br />Area <br />(SF) Proration <br />Factor Prorated <br />Area <br />(SF) <br />Phases <br />Current Whirlwind Mine decline 42,285 0 0 C, I, II, III <br />Current open area in ore zone 14,992 100 14,992 C,1, II, III <br />Packrat drift (bulkheaded) 113,295 50 56,648 II, III <br />Phase I drift area 27,129 50 13,564 1, II, III <br />Phase II drift area 79,102 50 39,551 11, 111 <br />Phase III drift area 407,453 50 203,726 III <br />Anticipated open area in ore zones 87,000 100 87,000 1,11,111 <br />C = Current Conditions <br />The estimated radon emissions for each phase were then calculated from the prorated <br />areas and the annual baseline emission rate of 0.18 Ci/1,000 SF. The estimates are <br />provided in Table 3. <br />13