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Environmental Health - Toxic Substances

Toxics Program Remediation Activities

Acidic Plume Remediation Monitoring

  • Performance Monitoring
  • Natural Attenuation
Location Pinal Creek, AZ (near Globe, AZ)
  • Pump and Treat
  • Monitored Natural Attenuation
  • Metals
  • Low pH Waters

USGS scientists have conducted long-term monitoring and field experiments at the site of an acidic plume of contaminated ground water that discharges to Pinal Creek, AZ. The plume is the result of acidic-mine drainage from copper mining activities in the Pinal Creek Basin. Information from USGS studies has been used by the Pinal Creek Group to help develop a cost-effective plan for remediation of the aquifer, and the Arizona Department of Environmental Quality (ADEQ) has used USGS aquifer data to help design a sampling plan for the remedial investigation of the site.

USGS scientists are monitoring the performance of the remediation at the site using a network of wells and surface-water sampling sites that is also used to investigate the fate of acidic plume. Initial monitoring results have had an impact on remediation plans for the site. For example:

  • Despite ongoing remedial pumping during the first phase of a pump and treat ground-water remediation effort, USGS water-quality monitoring data indicated the continued degradation of water quality in Pinal Creek, as a result of the discharge of contaminated ground-water to the part of Pinal Creek where there is perennial streamflow. These results prompted State and Federal regulators (ADEQ and the U.S. Environmental Protection Agency, respectively) to collaborate with the Pinal Creek Group to speed up the construction and implementation of a water-treatment plant that could clean up contaminated water in Pinal Creek. (Arizona Water-Quality Revolving Fund Administrative Order, Docket No. W-38-98.)

  • USGS scientists have also identified unexpected interactions between remediation activities and natural attenuation processes at the site. For example, ground-water pumping to divert contaminated ground water to a water-treatment plant had the unexpected effect of changing the natural characteristics of the stream channel, subsequently increasing the effectiveness of natural processes that remove metal contaminants from streamflow in Pinal Creek. This demonstrates the potential for the enhancement of engineered remedial activities by natural processes. Following the startup of the water-treatment plant, USGS scientists have continued the monitoring program to assess the long-term effectiveness of the water-treatment process.
More Information
  • Arizona Water Science Center
  • Jud Harvey, USGS, National Research Program, Reston, VA,
Brown, J.G., Bassett, R.L., and Glynn, P.D., 1998,
Analysis and simulation of reactive transport of metal contaminants in ground water in Pinal Creek Basin, Arizona, in Steefel, C.I., and Van Cappellen, P., eds., Special Issue--Reactive Transport Modeling of Natural Systems: New York, Elsevier, Journal of Hydrology, v. 209, p. 225-250.
Fuller, C.C., and Harvey, J.W., 2000,
Reactive uptake of trace metals in the hyporheic zone of a mining-contaminated stream, Pinal Creek, Arizona: Environmental Science and Technology, v. 34, no. 7, p. 1150-1155.
Glynn, P.D., and Brown, J.G., 1996,
Reactive transport modeling of acidic metal-contaminated ground water at a site with sparse spatial information, in Lichtner, P.C., Steefel, C.I., and Oelkers, E.H., eds., Reactive Transport in Porous Media: Washington, D.C., Mineralogical Society of America, Reviews in Mineralogy, v. 34, p. 377-438.
Harvey, J.W. and Fuller, C.C., 1998,
Effect of enhanced manganese oxidation in the hyporheic zone on basin-scale geochemical mass balance: Water Resources Research, v. 34, no. 4, p. 623-636.

USGS Acid Mine Drainage Remediation Projects

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