Evaluating Acid Mine Drainage Cleanup Strategies
The influx of metal-rich groundwater from natural springs (foreground) to Cement Creek, Colorado (background) can complicate the selection of best management practices. Photo credit: Briant Kimball, USGS. ( Larger version) Field-study and computer simulation tools developed by a team of U.S. Geological Survey (USGS) scientists were shown to be effective for evaluating strategies to reduce acid mine drainage in streams. The tools were used to estimate post-cleanup water quality in two streams—Cement Creek and Mineral Creek— impacted by abandoned mines in Colorado. The tools consist of prescribed field studies and computer simulation models. The field studies collect water-quality and other data to estimate the mass of contaminants delivered to streams and transported downstream. The computer models are used to quantify the transport of dissolved metals in streams and can be used for comparative analysis of cleanup alternatives.
For Cement Creek, the scientists used the tools to evaluate proposed best management practices to meet and develop regulatory standards know as Total Maximum Daily Loads (TMDLs) for the stream. They found that the effects of chemical transformations in the stream and contributions to stream-water quality from groundwater sources may significantly decrease the effectiveness of the best management practices proposed in TMDL standards.
For Mineral Creek, the scientists used a computer simulation model to accurately forecast post-cleanup water quality in the stream. A comparison of model results based on data before the cleanup with water-quality data from the stream after the cleanup indicates that the model correctly forecast attainment (or non-attainment) of water-quality standards in 19 of the 25 scenarios considered.
These studies were made possible through funding from the USGS
Toxic Substances Hydrology Program,
San Juan County, Colorado,
San Juan Resource Conservation and Development Program, and
U.S. Environmental Protection Agency; and through cooperation with the Animas River Stakeholders Group.
The Silver Ledge Mine in the area of upper Mineral Creek, near Silverton, Colorado, is one of many abandoned mine sites in the watershed. Photo credit: Philip Verplanck, USGS
( Larger version) References
Walton-Day, Katherine, Runkel, R.L., and Kimball, B.A., 2012, Using spatially detailed water-quality data and solute-transport modeling to support total maximum daily load development: Journal of the American Water Resources Association, doi: 10.1111/j.1752-1688.2012.00662.x
Runkel, R.L., Kimball, B.A., Walton-Day, K., Verplanck, P.L., and Broshears R.E., 2012, Evaluating remedial alternatives for an acid mine drainage stream—A model post audit: Environmental Science and Technology, v. 46, no. 1, p. 340-347. doi:10.1021/es2038504
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