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prescribed regulatory levels to determine the classification of the tailings. <br />In the case of the San Luis tailings samples, all EPA Method 1312 leachates Mere analyzed for <br />a considerably greater range of species. These parameters were: <br />pH, alkalinity, bicarbonate, carbonate, chloride, conductivity, total cyanide, weak <br />acid dissociable cyanide, hydroxide, total dissolved solids, arsenic, barium, <br />boron, cadmium, calcium, chromium, copper, iron, lead, mercury, magnesium, <br />manganese, molybdenum, nickel, potassium, selenium, silver, sodium, and zinc. <br />These parameters were analyzed in order to fully assess the potential leachability and the pore <br />water chemical environment of the BMRI tailings. <br />2.4 Column Test Prog_~m <br />As discussed in Section 2.2, each of the sample locations was augured as double holes (or <br />twinned) to allow collection of sufficient sample material for geochemical testing] and for column <br />leach tests. SRK in Denver performed column leach testing of the tailings material. Holes 1, <br />4, 6, 8, and 12 were chosen for the column leach tests. These holes were sdlected based on <br />depth, sample recovery, and to provide information from varying locations wikhin the tailings <br />facility. <br />2.4.1 Test Apparatus <br />The column leaching test apparatus consists of a five-inch inside diameter acrylic column with <br />square base plates on the top and the bottom. Figure 2.6 is a schematic of the column leach test <br />apparatus. The apparatus is directly connected to a head tank above the colu~n and a sealed <br />tail tank below the column. The head tank serves as a reservoir to store all initial leaching fluid. <br />Primary leaching fluid is introduced to the sample directly from the head tank through a small <br />diameter tube. The tail tank serves as a collection vessel for all leachate g$nerated during <br />l6 <br />