Water-Quality Monitoring at an Abandoned Mine Land Reclamation Site Amended with Fly Ash and Fixated Scrubber Sludge

摘要

A four-year monitoring project begun in1995 provides information from the first use ofcoal-combustion by-products (CCBs) in the reclamationof abandoned mine lands in Indiana. The IndianaDepartment of Natural Resources, Division ofReclamation, is interested in demonstrating the useof fixated scrubber sludge as cap and bottom ash asstructural fill material. Water-quality monitoring atthe site was initiated one year before reclamationactivity began and has continued on a quarterly basisthrough more than one year of post-reclamationmonitoring. The two primary objectives of themonitoring program are to determine the effectivenessof acid-mine drainage abatement and to monitor theleaching of solutes from the CCBs. Water from severalmonitoring wells screened at different depths and indifferent materials, and several surface dischargepoints have been sampled for pH, specific conductivity,alkalinity, acidity, iron species, major cations,major anions, the inorganic priority pollutants, andother selected minor and trace elements.Post-reclamation surface drainage leaving the sitehas changed from acidic to alkaline. At present thewater in surface drainage contains decreasedconcentrations of iron and aluminum and increasedconcentrations of calcium. Monitoring wells screenedin CCBs and at interfaces between CCBs and non-CCB fillmaterial show signs of improving overall ground-waterquality due to altered hydrology and reaction withCCBs. Significantly increased concentrations of boron,molybdenum, potassium, and chloride were found inmonitoring wells screened in or near CCBs. However,at the site outlet the concentration of boron has notincreased, and potassium, chloride, and molybdenum have increased only slightly.