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U.S. Department of the Interior NON, CONFIL)C-NT1AL <br />U.S. Geological Survey <br />U.S. Geological Survey Scientific Investigations Report 2004-5104 <br />Text version for 508 compliance <br />Use of Short-Term (5-Minute) and Long- <br />Term (18-Hour) Leaching Tests to <br />Characterize, Fingerprint, and Rank Mine- <br />Waste Material from Historical Mines in the <br />Deer Creek, Snake River, and Clear Creek <br />Watersheds in and around the Montezuma <br />Mining District, Colorado <br />By Philip L. Hageman <br />Abstract <br />Precipitation-induced runoff from historical mine-waste located adjacent to the headwaters of the <br />Snake River, Deer Creek, Saints John Creek, Grizzly Gulch, Stevens Gulch, and Leavenworth Creek <br />contributes to the degradation of water quality in these streams. Because historical mine-waste piles have <br />had long-term exposure to the atmosphere, it is surmised that runoff from these piles, induced by <br />meteorological events such as cloudbursts and snowmelt, may cause mobility of acid and metals into a <br />watershed due to dissolution of soluble minerals. For this study, 13 mine-waste composite samples from <br />various mine-wastes in these drainage basins were leached using both a short-term and a long-term leach <br />test. Analytical results from this combination of leach tests are tools that allow the investigator to quantify <br />(fingerprint) which geochemical components could be expected in runoff from these piles if they were <br />leached by a cloudburst (5-minute leach test), as well as what the "worst-case" geochemical profile would <br />look like if the material were subject to extended leaching and breakdown of the mine-waste material (18- <br />hour leach test). Also, this combination of leach tests allows the geoscientist the ability to see geochemical <br />changes in the mine-waste leachate over time. That is, does the leachate become more or less acidic over <br />time; does the specific conductance increase or decrease; and are there changes in the concentrations of <br />major or trace elements? Further, use of a ranking scheme described herein will aid in prediction of which <br />historical mine-waste piles have the greatest potential for impact on a watershed should runoff occur. <br />Because of long-term weathering of these historical mine-waste piles, geochemical profiles, <br />leachate time-trends, and relative ranking of the mine-wastes produced from analysis of the leachates are <br />Hageman_SIR_2508.doc 1 7/21/2004 2:50 PM