THE EFFECT OF MINE DRAINAGE ON TOMHICKEN CREEK, SCHUYLKILL COUNTY PA: ANALYSIS OF WATER CHEMISTRY AND METAL DEPOSITION

This study was conducted in Fall 2006 to characterize the effects of the water chemistry of the Oneida 3 coal mine tunnel drainage on the water of Tomhicken Creek. Two sample sites were located in the mine drainage and two sample sites were in Tomhicken Creek above the confluence with the mine drainage. Samples were collected on both sides of the stream at the confluence and on both sides of the stream 25m and 50m below the confluence. Triplicate water samples were collected and acidified for analysis of dissolved Fe, Al, Pb, and Mn concentrations. Additional triplicate samples were collected for analysis of sulfate, alkalinity, and acidity. Temperature, pH, oxidation-reduction potential (ORP), and conductivity were measured on site. The highest Mn and Al concentrations, 0.20 ppm and 0.65 ppm respectively, were in the mine drainage before the confluence with the stream. Manganese was undetectable at sites below the confluence. Dissolved aluminum was highest in the mine drainage and the concentration progressively decreased below the confluence, to 0.04 ppm at the last sample site. Alkalinity was lowest in the mine drainage (1.5-1.8 mg/L as CaCO₃) and highest in Tomhicken Creek upstream of the confluence (9.50 mg/L as CaCO₃), decreasing to 2.73-4.73 mg/L as CaCO₃ at the most downstream site. Compared to other coal mine drainage sites in Pennsylvania, the pH of the Oneida 3 drainage was relatively high (5.50). The pH range above the confluence was 6.30-6.99 while the pH range below the confluence was 6.20-6.40. In general, ORP increased as pH decreased. Sulfate was highest (40.3 ppm) in the mine drainage. The mine drainage increased sulfate concentrations of Tomhicken Creek from 24.3 ppm above the confluence to an average of 32.2 ppm at the last sample site. The conductivity of Tomhicken Creek (272 µS) was several times higher than the conductivity of the mine drainage (76 µS). Sediment samples from the confluence were imaged with a scanning electron microscope and sediment composition was determined with energy dispersion x-ray spectroscopy (EDS). SEM/EDS indicated the rocks at the confluence on the side most affected by the mine drainage were coated with colloids high in aluminum, probably aluminum hydroxides.