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L~ ~ . 2 U11SAlIIRATSD TAILIIiGS COLUlftl 3.2.1 SAMPLE FLACEMENT 51ITHIN THE COLUMN As with the previous column a 2 inch layer of sand would be Dlaced on the bottom of the column to simulate the underdza n system. The tailings as received would be re-slurried to SOk solidi content and placed is the column in three lifts of equal weight a d height with bottom drainage open during deposition. The atmospher in this column would also be air. Therefore all drainage due to settlement would take place is two directions (top and bottom). The bot om drain would remain open for a minimum of 48 hours, prior to the addition of other lifts. The second and third lifts would be planed in a similar fashion. The settled density, saturated moisture content, calculated moisture content, and the total volume of voi s of the deposit would be calculated. At this point the column would be ready for leaching. 3.2.3 SAMPLE LEACHING For sample leaching the toy of the tailings would be s rchatged with enough simulated rainwater/snoxmelt to produce one po~e volume of leachate. All the water would be allowed to drain th ough the bottom prior to setting up for collection of the next por volume. The column would be allowed to drain for a minimum of 48 hors prior to initiating the sequence for each succeeding pore volu es. Five pore volumes will be collected. If needed the hydraulic gradient could be elevated to speed up the testing. This would be acc mplished by increasing the atmospheric pressure above the water. The pore volumes would be collected in bottles ope to the atmosphere. If the collected drainage contains un-oxidized dissolved solids, then oxidization of these dissolved solids could oc ur while the sample is being collected in the bottle. The bottom o~ column would also be exposed to some limited amount of air s ace the drainage line would be open to the atmosphere.