STREAM INFLUENCES ON ABANDONED MINE DRAINAGE REMEDIATION

Pennsylvania has played host to 200 years of coal mining that has resulted in the degradation of more than 5000 km of streams. While the government currently enforces environmental quality standards on mining operations, this was not always the case. The effects of coal-mine drainages (CMD) are numerous and include acidification of streams, high metal concentrations and a reduced capability to support life.

A study of 6 CMD sites in the Anthracite Coalfields of Pennsylvania was performed in the Fall of 2013 to examine the rate at which CO₂ is removed from streams just below the discharge point, and whether this rate is significant enough to affect metal concentrations. CO₂ forms carbonic acid in water, and when released as a gas results in an increase in pH. Complete hydrologic and inorganic aqueous geochemical data was collected at each discharge and 3 locations downstream: 10, 100, and 250 m.. Water samples were used to determine alkalinity, and cation analysis, and anion concentrations. Water quality data included measurements of flow, dissolved oxygen, temperature, pH, eH and specific conductance. To determine the mixing capability of the stream, a salt injection was performed and monitored 40 seconds of travel time downstream. Also, a spectrophotometer was used to determine the rate at which iron changes from ferrous to ferric iron and is subsequently precipitated. Correlations were identified between the contaminant loading, flow, and water quality data and were used to analyze the changes in the water quality as it travels from the discharge. Overall, concentrations of iron, manganese and nickel were found to decrease with distance, while pH increased, which was expected. The distances at which these reductions occurred varied, and have been correlated to stream characteristics such as slope, mixing and surface area.