CARBIDE LIME TREATMENT OF ACID MINE DRAINAGE IMPACTED SOILS IN THE HUFF RUN WATERSHED OF NORTHEAST OHIO

Active and abandoned mines are primary producers of acidic and sulfur-rich wastewater in the United States such that the USEPA estimates it will cost $32-$72 billion dollars to recover waters impacted by acid mine drainage. The extraction of coal leaves behind unconsolidated piles of surface waste called mine spoil. Once exposed to the surface, pyrite within these mine waste soils will begin to oxidize, releasing metals and acidity which can leach into nearby surface and groundwater systems. The aim of this study is to test an inexpensive and novel approach to treating AMD impacted soils through the application of a pH 13 carbide lime slurry in an attempt to neutralize acidity and sequester mobile metals. Joint field and laboratory studies are being conducted in order to determine the chemical and physical interactions that take place between carbide lime and AMD soils. The field portion of this study consists of monitoring the changes in near surface water quality of two AMD impacted hillslopes which are being treated with carbide lime slurry. The laboratory portion consists of a column experiment intended to simulate treated and untreated mine spoil interactions with rainwater in a controlled setting. Treated and untreated solid and aqueous samples will undergo analysis via a suite of instrumentation to determine the reaction products of our treatment efforts. Solid phase characterization will be determined through X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), elemental analysis (EA), and synchrotron-based X-ray microprobe (XMP). Aqueous phase characterization will be determined through inductively coupled plasma optical emission spectroscopy (ICP-OES), ion chromatography (IC), and total organic carbon (TOC).