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Page 3 December 19, 2013 Response: To evaluate the composition of leachate from mine water percolating through the waste rock, OOSI conducted leachate testing consistent with the Synthetic Precipitation Leaching Procedure (SPLP). Three test pits were excavated on the Lower Bench in the area proposed for construction of infiltration trenches; each pit was excavated to a depth of 5 ft. One waste rock composite sample was collected at each test pit by combining three channel samples (1.5 ft. vertical channels) collected from the 3.5 to 5.0 depth interval in each pit. Each composite sample consisted of approximately 2 gallons of rock. During sampling of the waste rock, there was no indication of any foreign anthropogenic chemical contaminants in the test pits. Mine water from Outfall 001 (sample location LW-001) was collected in multiple 1 to 3 gallon cubitainers. All samples were submitted to the analytical laboratory (TestAmerica Pittsburgh). OOSI worked with the lab to assure proper analytical procedures. Because the submitted waste rock consisted of a sizable coarse fraction, leaching tests were conducted for both the fine (less than 9.5mm) and coarse (greater than 9.55 mm) fractions for each test pit sample. The test procedure followed SPLP protocols which involved agitated exposure of waste rock and mine water for a minimum of 18 hours. Laboratory analysis was conducted of the original mine water and the resulting leachate from each prepared test container. A total of 6 leachates were analyzed, including a fine and a course waste rock leachate from each of three test pits. One duplicate sample was analyzed for Test Pit No.2. Table 2 presents the results of the 001 mine water and waste rock leaching tests. Note that only the fine fraction leachates were analyzed for the hydrocarbon parameters of total petroleum hydrocarbons (diesel range), oil and grease, and total phenols. This is because the leaching agitation process normally occurs in glass containers but the coarse fraction used plastic containers to prevent container breakage during the agitation phase. Gasoline range hydrocarbons were not evaluated because of their high volatility and a lack of field evidence that such hydrocarbons were present in the waste rock. Other parameters analyzed included wet chemistry, common ions, and metals. The results of the leaching tests show that TPH (diesel range) was not detected in any of the leachate samples. Oil and grease was not detected in two of the pit leachate samples and was detected at levels between the method detection limit and quantitation limit in two leachate samples (1.5 and 1.9 mg/L) and in the mine water sample (1.9 mg/L). Total phenols were detected in 3 of the 5 leachate samples at concentrations slightly above the detection limit of 0.010 mg/L at 0.012, 0.013, and 0.014 mg/L. All of the reported total phenol concentrations were well below the state water quality standard for phenol of 2.1 mg/L. The low detected concentrations of oil and grease and phenols are interpreted to be of a natural, not synthetic, origin (plants and other natural organic compounds contain phenols and oil and grease). It is also possible that the very low oil and grease detections are from minor amounts of these constituents in the waste rock from handling the material by various mining machinery. Metals results in the leachate indicated that some metals concentrations were less than the background concentrations in the mine water and others were greater than the background mine water. Leachate concentrations less than the background mine water concentrations indicate adsorption of the constituent by the waste rock material. Leachate concentrations greater than the mine water concentrations indicate potential leaching constituents. Table 3 lists some common constituents of concern and their general tendency for adsorption or leaching in the mine water and waste rock leaching tests. WarshaII121713.doc