A Full-Scale Porous Reactive Wall for Prevention of Acid Mine Drainage |
| |
| Authors: | Shawn G Benner David W Blowes Carol J Ptacek |
| |
| Institution: | Shawn Benner;is currently a Ph.D. candidate in the Earth Sciences Department at the University of Waterloo (Waterloo, Ontario, N2L 3G1, Canada, 888–4567). He received a bachelor's degree in geology from The Colorado College, Colorado Springs, and his master's degree from the University of Montana, Missoula, Montana. He is pursuing his Ph.D. on the use of porous reactive walls for acid mine drainage. Carol Ptacek;is an adjunct professor in the Earth Sciences Department at the University of Waterloo (Waterloo, Ontario, N2L 3G1, Canada, 888–4567). She received her Ph.D. from the University of Waterloo in 1992. Her research focuses on transport of dissolved metals and nutrients in aquifers, and on the development of ground water remediation techniques. David Blowes;is an associate professor in the Earth Sciences Department at the University of Waterloo (Waterloo, Ontario, N2L 3G1, Canada 888–4567). His primary research interests pertain to the inorganic geochemistry of ground water and surface water systems, including the prediction, remediation, and prevention of ground water contamination associated with the mining industry, and passive geochemical control barriers. |
| |
| Abstract: | The generation and release of acidic drainage containing high concentrations of dissolved metals from decommissioned mine wastes is an environmental problem of international scale. A potential solution to many acid drainage problems is the installation of permeable reactive walls into aquifers affected by drainage water derived from mine waste materials. A permeable reactive wall installed into an aquifer impacted by low-quality mine drainage waters was installed in August 1995 at the Nickel Rim mine site near Sudbury, Ontario. The reactive mixture, containing organic matter, was designed to promote bacterially mediated sulfate reduction and subsequent metal sulfide precipitation. The reactive wall is installed to an average depth of 12 feet (3.6 m) and is 49 feet (15 m) long perpendicular to ground water flow. The wall thickness (flow path length) is 13 feet (4 m). Initial results, collected nine months after installation, indicate that sulfate reduction and metal sulfide precipitation is occurring. Comparing water entering the wall to treated water exiting the wall, sulfate concentrations decrease from 2400 to 4600 mg/L to 200 to 3600 mg/L; Fe concentrations decrease from 250 to 1300 mg/L to 1.0 to 40 mg/L; pH increases from 5.8 to 7.0; and alkalinity (as CaCO3) increases from 0 to 50 mg/L to 600 to 2000 mg/L. The reactive wall has effectively removed the capacity of the ground water to generate acidity on discharge to the surface. Calculations based on comparison to previously run laboratory column experiments indicate that the reactive wall has potential to remain effective for at least 15 years. |
| |
| Keywords: | |
|
|
