Treatment of drainage from an underground coal mine, abandoned for over 65 years, has been a focus of the Jennings Environmental Education Center (a Pennsylvania State Park) since failure of a mine seal in 1984. Early prototypes of environmentally-friendly technologies or passive treatment components have been installed and monitored since 1989. As Jennings is dedicated to environmental education at various interest levels for the general public and for students of all ages, water monitoring to demonstrate the performance of the system has been imperative. In 1997, a Vertical Flow Pond (VFP) with treatment media consisting of 272 metric tons (300 short tons) of spent mushroom compost mixed with 345 metric tons (380 short tons) [9.52 mm x 1.180 mm (3/8"x16 mesh); >90% CaCO 3 ] of limestone aggregate, a step-down (Bioswale) wetland, and an aerobic wetland/settling pond were installed to treat the acidic, metalladen, raw water which averages 76 Lpm (20 gpm), 3.0 pH, 270 mg/L acidity, 40 mg/L total iron, 15 mg/L total manganese, and 15 mg/L total aluminum. At the time of installation, the predicted optimum life of the VFP treatment media was 7 to 10 years with exhaustion in about 14 years. After over 12 years, however, the system continues to provide successful treatment with limited maintenance. The primary maintenance item has been two, approximately two-day, "stirring" events to address permeability of the treatment media. As a design schematic and analyses from over 200 water monitoring events (depending upon the component), conducted by numerous professionals, students, and volunteers, are publically available online at www.datashed.org, the passive system provides a valuable template for future designs and improvements. The final effluent of the system can be characterized as typically net alkaline with total iron, manganese, and aluminum concentrations of about 1 mg/L or less.
