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Grizzly Mine <br />The Grizzly mine is located in Grizzly Gulch in the Clear Creek watershed. The mine is hosted in <br />the Idaho Springs formation. <br />Net-Acidity <br />1.3 kg CaCO,/ton. <br />pH Trend <br />There was no change in pH over time in the Grizzly mine-waste leachate. pH stayed at 6.9 in both <br />the 5-minute and 18-hour leachates. The leachate was neither net-acid producing nor net-acid consuming. <br />Specific Conductance Trend <br />Grizzly leachate had low specific conductance with measurements of 25 µ&cm after 5 minutes, <br />increasing to 70 pS/cm after 18 hours. <br />Sulfate <br />Sulfate concentration was very low with concentrations of 5 mg/L after 5 minutes and 8 mg/L <br />after 18 hours. <br />Selected Major-Element Trends <br />This leachate had low calcium concentration that ranged from 1.8 mg/L in the 5-minute leach to <br />6.9 mg/L after 18 hours. <br />Selected Trace-Metal Trends <br />Following are summaries of selected trace-element trends portrayed in the time study (5-minute <br />vs. 18-hour) of the Grizzly mine-waste leachate. <br />Aluminum (AI).-This leachate had moderate aluminum concentration that ranged from 57.1 <br />µg/L in the 5-minute leachate and increased to 364 µg/L after 18 hours. <br />Cadmium (Cd).-Minor concentration of cadmium was found in the Grizzly mine-waste <br />leachate with values of <0.02 µg/L after 5 minutes, and 0.03 µg/L after 18 hours. <br />Copper (Cu).-Minor leachate copper concentration was found. Values ranged from 2.0 ttg/L <br />in the 5-minute leachate to 2.2 gg/L after 18 hours. <br />Iron (Fe).-Iron was found in low concentration in the leachate, and concentration increased <br />over time from <50 pg/L in the 5-minute to 129 pg/L after 18 hours. <br />Manganese (Mn).-Minor concentration of manganese was found in the Grizzly leachate. The <br />5-minute concentration was 2.7 µg/L and increased to 7.4 µg/L after 18 hours. <br />Mercury (Hg).-Mercury was not detected in the Grizzly leachate. <br />Nickel (Ni).-Nickel was found in low concentration in the leachate with a 5-minute <br />concentration of <0.4 µg/L that increased to 0.8 µg/L after 18 hours. <br />Lead (Pb).-Low concentration of leachate lead was found and concentration increased over <br />time from 4.8 gg/L after 5 minutes to 11.1 µg/L after 18 hours. <br />Zinc (Zn).-Minor concentration of zinc was found in the Grizzly leachate, and zinc <br />concentrations increased slightly over time. The 5-minute concentration was 5.7 µg/L; this <br />value increased to 9.9 gg/L after 18 hours. <br />Hageman_SIR_2508.doc 23 7/21/20042:50 PM