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DATES <br />ACTIVITY <br />STATUS <br />2005 - Present <br />Maintenance of existing <br />stormwater BMPs <br />Ongoing <br />TBD <br />Implementation of new <br />stormwater BMP's <br />Pending (application <br />approval) <br />TBD <br />Sealing of mine portal <br />Pending (post mining) <br />TBD <br />Removal of mining <br />facilities <br />Pending (post mining) <br />TBD <br />Site final reclamation <br />(grading, pocking, seeding) <br />Pending (post mining) <br />Transport modeling simulations conducted at similar sites as LP -21 were conducted by <br />Kearl (2005). The modeling was very conservative and followed NRC guidelines for <br />high -level radioactive waste repositories. Using published uranium Kd values for <br />transport calculations in sand and clay materials, it was determined that after 1000 years, <br />the relative concentration of these at depths of less than 100 feet below the base of the <br />waste rock pile would be 1 /1,000,000 of the initial concentration. <br />As previously discussed, once mining resumes at LP -21, representative ore samples will <br />be submitted for SPLP testing and the results evaluated and reported to the DRMS. <br />14.3 Acid Mine Drainage Potential <br />As discussed in Section 6.1.1, there is a low potential for the development of acid mine <br />drainage from the waste rock or ore stockpiles due to the chemical nature of the rock <br />forming minerals. Salt Wash sandstones are commonly calcareous meaning that calcium <br />carbonate cements the sand grains together forming sandstones. Water percolating <br />through the waste rock or ore stockpiles would be expected to become alkaline due to the <br />rock chemistry of the rock. EPA Method 1312 SPLP requires an acidic solution with a <br />pH of 5.0 be used for the tests. <br />As shown by the SPLP test results, pH of the water solution passed through the rock <br />samples is 9.4 or alkaline. The waste rock acts as a buffer to acidic solutions. This result <br />is consistent with the rock chemistry and shows that there is no potential for waste rock <br />piles to form acid mine drainage. <br />(15) Construction Schedule Information <br />This site has been fully reclaimed. Construction of stormwater diversion and <br />containment structures, as well as portal construction and mine yard facilities, are <br />outlined in Table 4 below. <br />Table 4: Construction Schedule <br />TBD = dates to be determined <br />O'Connor Design Group Inc. <br />U -21 <br />