Synthetic Precipitation Leaching Procedure (SPLP) leachate chemistry data for solid mine-waste composite samples from southwestern New Mexico, and Leadville, Colorado

Abstract

This report details chemistry data derived from leaching of mine-waste composite samples using a modification of E.P.A. Method 1312, Synthetic Precipitation Leaching Procedure (SPLP). In 1998, members of the U.S. Geological Survey Mine Waste Characterization Project collected four mine-waste composite samples from mining districts in southwestern New Mexico (CAR and PET) and near Leadville, Colorado (TUC and MII). Resulting leachate pH values for the four composites ranged from 5.45 to 8.84 and ranked in the following order: CAR < TUC < MII < PET. Specific conductivity values ranged from 85 μS/cm to 847 μS/cm in the following order: PET < MII < CAR < TUC. Geochemical data generated from this investigation reveal that leachate from the CAR composite contains the highest concentrations of Pb, Zn, Ni, Mn, Cu, Cd, and Al Introduction Assessing acid and metal mobility from abandoned mine-waste piles is an area of concern for Federal land management agencies and others. Drainage and runoff from these piles can present water quality concerns similar to acid mine drainage. Mine-waste piles that contain metal and sulfide reservoirs can become sources of acidic drainage when exposed to surface conditions of oxygen and water. Continuing work on Abandoned Mine Lands projects has demonstrated the need for rapid, accurate characterization of these waste materials in order to aid in the screening, geochemical assessment, and prioritization of a large number of mine-waste piles for remediation. One of the methods currently used to characterize mine-waste material is E.P.A. Method 1312 Synthetic Precipitation Leaching Procedure (SPLP). Because this test has been used in many studies involving mine-waste it was the method we chose for the geochemical characterization of the samples in this study. It is important to note, that we have observed while conducting this and other studies, that some of the procedures required when using EPA Method 1312, such as particle size reduction, end-over-end rotary agitation, and extended extraction time (18 hours) probably remove most realistic approximations of simulating runoff from mine-waste. Purpose of Investigation The purpose of this investigation is two-fold: First, it provides our collaborators an assessment of EPA Method 1312 leachate chemistry data for solid mine-waste composite samples collected from four different mine-waste sites. Second, data from this investigation were used for comparative studies as part of a larger effort to develop a field leach test (Hageman and Briggs, in press) which is designed and used as a screening tool for evaluation of historic mine-waste piles.