U.S. Geological Survey (USGS)
Kate Campbell is a biogeochemist with the Geology, Geophysics, and Geochemistry Science Center, Energy and Minerals Mission Area, U.S. Geological Survey in Boulder, CO. She received a BS in Chemistry from Georgetown University and an MS and PhD in Environmental Engineering from the California Institute of Technology. Her research focuses on abiotic and biotic redox chemistry of natural waters, including acid rock drainage, mining impacted waters, geothermal waters, and groundwaters, In particular, she studies the biogeochemistry of iron, arsenic, antimony, and uranium, and develops biogeochemical models of kinetically controlled redox processes.
Iron-rich Scaling in Acid Mine Drainage Pipelines: Mineralogy, Biogeochemical Modeling, and Remediation Strategies
Historical mining at Iron Mountain (CA) and Leviathan Mine (CA) has produced on-going drainage that is acidic and metal-rich. At Iron Mountain, the site was the source of thousands of kilograms per year of Cu, Zn, Cd, and other metals to tributaries of the Sacramento River, prior to initial remediation in 1994. On-going remediation includes water treatment by lime neutralization producing high-density sludge. As a result, metal concentrations decreased by 95%. At both mine sites, water is conveyed to a treatment plant through a series of pipelines from the most contaminated drainages, seeps, and adits. Microbial Fe(II) oxidation of the acidic mine drainage in the pipelines results in precipitation of hydrous Fe(III) oxides and oxy-sulfates (primarily schwertmannite with minor amounts of goethite), requiring expensive maintenance. The pipeline precipitates host a diverse group of acidophilic microorganisms and contain elevated concentrations of metals and metalloids. Laboratory experiments and geochemical modeling suggest that decreasing the pH of the acid mine drainage through acid amendment or mixing of different source waters, including acid mine drainage with pH as low as 0.5 at Iron Mountain Mine, could be a viable option to prevent or retard precipitation in the pipeline. A combination of laboratory experiments and field measurements has informed the development of a biogeochemical reactive transport model that can be used to test various remediation options at the mine sites.
• Kate Campbell, Geology, Geophysics, and Geochemistry Science Center, USGS, Lakewood, CO
• Charles Alpers, California Water Science Center, USGS, Sacramento, CA
• D. Kirk Nordstrom, Hydrological and Ecological Interactions Branch, USGS, Boulder, CO