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~ 3. Seal Decline and Reclaim Ore Pad Area <br />The Whirlwind Mine will require two bulkhead seals placed in the decline to ensure that the water <br />seeping into the decline from the lower Brushy Basin aquifer is not allowed to enter the mine <br />workings. The lower bulkhead will be constructed neaz the base of the decline at an elevation of 6771 <br />feet. The seal location and design will require approval from the DRMS prior to installation. The <br />hydraulic loading on this seal is expected to be relatively low i.e., about 60 feet of hydraulic head <br />based on 1,000 feet of Brushy Basin intercept on a 6 % grade. The seal will be placed in a thick <br />mudstone zone so that ground water from above cannot seep through the surrounding rock. For <br />reclamation bonding purposes, construction of an 18 inch-thick concrete seal with rebaz is assumed. <br />The seal will be notched and anchored into the surrounding tunnel walls, ceiling, and floor. <br />The upper seal will be placed at an elevation of 6848 feet, which is immediately above the highest <br />location where water is entering the decline. This seal location is approximately 2/3 of the distance <br />down the decline from the surface. This bulkhead will be constructed of concrete blocks notched 1 foot <br />• into the surrounding tunnel walls, ceiling and floor. The blocks will be 8 inches in thickness. <br />The estimated cost of the thicker concrete seal with rebaz is $7,000 and the cost of the block seal is <br />$2,000. Therefore, the total estimated cost of mine seals is $9,000. <br />Over the life of the mine, percolation of rain water through the ore may result in radionuclides leaching <br />into the compacted pad immediately below it; therefore, the top 18 inches of the pad will be excavated <br />over the 0.5 acre stockpile azea shown on Map C-2. This material will be disposed of inside the mine <br />above the upper seal. This azea of the decline is dry and the material will not be in contact with ground <br />or meteoric water. The calculated volume of pad material is 1,210 cubic yards. The pad area <br />immediately below the upper 18 inches will also be tested for Radium 226. If these tests show that <br />some of the remaining material is above levels found in the surrounding waste rock material, it also <br />will be excavated and placed in the mine. Because the pad will be compacted, percolation below the <br />18-inch depth is not expected. The cost of this excavation, haulage and placement is $10 per cubic yazd <br />resulting in an estimated cost of $12,100. The total estimated cost for this task including seal <br />`) installation is $21,100. <br />YVhirlwind Mine June 07 E-4 <br />