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commitment to additional sampling, and (b) evaluates the additional geochemical data <br />in light of previous geochemical testing of tailings materials. <br />zssuEs <br />1. Dots long-terns leaching of tailings samples from the five new samples indicate that <br />long-term leaching by meteoric water will lead to acidic effluents? <br />3. What is the range of port-water chemistries derived from the Cve new samples? <br />3. What are the acid-base accounts'For the samples, and bow do these data compare to <br />the acid-base accounts for pre-operational samples and the earlier samples from the <br />Lower Impoundment? <br />4. Does leaching of the new samples using EPA Method 1312 indicate that effluents <br />from the tailings have a potential to degrade water resources, and how do these data <br />compare to Iviethod 1312 leaching data for pre-operational samples and the earlier <br />samples from the Lower Impoundment? <br />5. Based on the test data, is there a basis for assuming that the tailings materials in the <br />Lowes Impoundment differ geochemically irom tailing materials characterized <br />under pre-operational conditions ~ ways that could adversely affect water <br />resources. <br />METHODS <br />BMRI collected both tailings samples and coexisting pore water from each of the five <br />sample intervals identified above. <br />The pore water samples were analyzed a[ Core laboratories (Aurora. Colorado) for the <br />same water-chemistry parameters for which column leach testing acrd EPA Method <br />1312 leach testing had been analyzed in the data presented by BIvfR.l in May, 1993. <br />The tailings solids were tested in three manners: <br />1. Sequential rinsing with 20:1 water:solids steps. The rinsate was de-iotuzed water <br />with pH adjusted to the range of 5.0 - 5.5 to simulate natural meteoric waters. The <br />purpose of the rinsing steps was to evaluate (a) the rate at which easily solwbilizcd <br />products can be removed from the tailing by simple rinsing and (b1 [he pH and <br />conductivity (a surrogate for total dissolved solids) of the rinsa[e solutions at each, <br />sequential step. <br />GeoehUnicq fret. 2 26 September, 1996 <br />