Fate and transport of contaminants from acid mine drainage in the Perry Canyon Abandoned Mine Land, Washoe County, Nevada
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Perry Canyon abandoned mine land (AML) hosts acid mine drainage from abandoned mine workings with elevated levels of toxic heavy metals that may be contaminating municipal water in the town of Sutcliffe, Nevada. The objective of this thesis is to assess the potential for contamination of downgradient municipal supply wells and natural resources through data analysis and modeling techniques. Results from the data analysis show that contamination is present near the sources but diminishes downgradient. Additionally, an analytical water balance analysis predicts that percolation is occurring through the thin sections of waste rock and is confirmed by a numerical water balance model that predicts percolation rates of 2 – 183 mm/year.Groundwater and contaminant transport models are developed for the AML to further evaluate the potential of downgradient contamination. The groundwater model shows that there are gaining and losing reaches of the ephemeral Perry Creek, indicating contaminants may be exchanged between groundwater and surface water. The transport model simulates the estimated time for contaminants to reach the boundaries of Perry Canyon and the mass fluxes. The model results suggest that the estimated concentrations at the system boundaries are lower than the Environmental Protection Agency (EPA) maximum contaminant levels (MCLs). Thus, results indicate that the potential for downgradient contamination exposure to humans near municipal supply wells is low, however, there is contamination approximate to the sources that can have negative impacts on the ecology and environmental resources in the AML.