ACID MINE DRAINAGE (AMD) SITES IN CENTRAL PENNSYLVANIA: BIG MINE RUN VERSUS STIRLING DISCHARGE

Big Mine Run, an acid mine drainage (AMD) stream, is in the Western Middle Anthracite Field of Pennsylvania and exits the Centralia Tunnel from an extensive abandoned deep mine near Ashland, PA. The Stirling Discharge Tunnel is near Shamokin, PA, also in the Western Middle Anthracite Field but with access to a different deep mine system that is the source for another AMD stream. Water quality of both AMD sites was assessed in 1975 and again in 1991, allowing us to monitor changes in water quality over thirty years. Replicate water samples from each site were collected and analyzed for pH, TDS, dissolved oxygen, and temperature (in the field). Alkalinity, acidity, hardness, nitrates, orthophosphates and sulfates were analyzed using Hach procedures. Metals (Fe, Ni, Mg, Ca, Cu, Zn, Hg, Pb) were analyzed utilizing flame atomic absorption spectroscopy. Iron, nickel, and zinc were the dominant metals found in this year’s study, and iron concentrations were slightly elevated compared to historical values. Sulfate was abundant at both sites, but reduced from historical values. pH values are presently as low or lower than reported in earlier studies, indicating there is still abundant dissolution of pyrite at depth.