ONEIDA #3 ACID MINE DRAINAGE (AMD) TREATMENT FACILITY (LUZERNE COUNTY, PA): EFFICACY OF TREATMENT ON pH, ALUMINUM, AND ALKALINITY DURING LOW MINE DISCHARGE

Drainage from the Oneida #3 mine tunnel, in the Eastern Middle Anthracite Field of eastern Pennsylvania, discharges into Little Tomhicken Creek near Hazleton, PA. The second largest discharge in the Catawissa Creek Watershed, this discharge has historically had high concentrations of dissolved aluminum, low pH and low alkalinity, creating problems downstream. A passive limestone treatment system was installed in December, 2009. On 17 September 2010, we executed a field study to check the efficacy of the system in treating the AMD chemistry. We collected samples from twelve sites: two sites in the drainage tunnel, sites in Little Tomhicken Creek both upstream (2) and downstream (5) of its confluence with the AMD, and within the system itself. Dissolved oxygen, pH and specific conductance were measured in situ. Large (4L) samples were collected at each site and turbidity was determined. Filtered subsamples (GFF 0.70 µm effective pore size) were immediately analyzed for both acidity and alkalinity. Triplicate non-filtered and filtered subsamples were acidified with nitric acid to pH < 2, and kept chilled for later metal analysis. Additionally, triplicate filtered subsamples were placed on ice and placed in the freezer upon return to the laboratory for later anion analysis.

The treatment system is performing as designed with regard to increasing pH (5.3 to 7.5) and increasing alkalinity (1.7 to 10.4 mg/L as CaCO₃) of the AMD from tunnel to system outflow. The pH, fluoride, chloride, calcium, and specific conductance were higher in Tomhicken Creek above the tunnel (8.7, 14 ppm, 29 ppm, 30.7 ppm, and 1710 µS/cm, respectively) than in the outflow from the treatment system (7.5, 3 ppm, 2 ppm, 11.2 ppm, and 204 µS/cm, respectively). Analyses for aluminum concentrations were problematical in that the numbers were unreasonably high, so before we report the values, these samples must be reanalyzed. We do have some concern that the system may be only temporarily sequestering aluminum hydroxide. There was a thick layer of fluffy white aluminum hydroxide in the limestone tank in February 2010, two months after the system became operational, that was not evident in the tank either in July or September. Where did it go?????