GEOCHEMICAL EFFECTS OF PASSIVE LIMESTONE TREATMENT ON ONIEDA #1 ACIDIFIED MINE DISCHARGE NEAR HAZLETON (LUZERNE CO.), PENNSYLVANIA

A passive oxic limestone drain treatment system is installed and operational for treating acid mine drainage from the Oneida #1 drainage tunnel on the property of Eagle Rock Resort, Hazelton, PA (Luzerne, Co.). The main environmental issues at this mine drainage site have historically been low pH and high dissolved aluminum rather than high dissolved iron and sulfate. The mine effluent is diverted through a two-tiered gravity-fed system, each with three drains of trapezoidal cross-section filled with over 9,000 tons of limestone rock. Treated water flows into a flushing pond before draining subterraneously into Sugarloaf Creek. On 31 October, 2008, we were invited to sample the system to assess the effectiveness of treatment on water quality. We collected samples at 15 sites above, below, and within the system and performed in situ measurements of pH, temperature, dissolved oxygen, and conductivity. The collected samples were later analyzed for alkalinity, acidity, sulfate, and various dissolved metals. Serendipitously, the central drain valve had not been closed after the last flushing, thereby allowing us to compare the effectiveness of AMD treatment through the other drains. Drains appeared to be working, as pH changed from 4.0 before treatment to 5.2 after treatment, sulfates drastically decreased, and calcium and alkalinity significantly increased throughout the treatment process.