USGS Grant Number: G14AS00014
Year Established: 2014 Start Date: 2014-09-01 End Date: 2015-08-31
Total Federal Funds: $86,543 Total Non-Federal Funds: $86,543
Principal Investigators: Kumar Ramachandran, Cas Bridge, Bryan Tapp
Abstract: The Tar Creek Superfund Site (TCSS) is located in Ottawa County, Oklahoma. The site consists of forty square miles of above ground mining waste, hundreds of miles of underground tunnels, and over one thousand mine shafts. There is an estimated 6.7 million cubic yards of waste rock and 9 million cubic yards of fine tailings present within the boundaries of the TCSS. Uncontrolled hazardous substance releases have been occurring at the site since at least 1979 when the U.S. Environmental Protection Agency (EPA) first documented acid mine drainage (AMD) flowing from the subsurface through abandoned mine shafts and boreholes (DeHay et al., 2004). The sulfide ores were hosted by the Mississippian-aged Boone Formation, which is 270 – 470 feet thick in northeastern Oklahoma and is comprised of alternating limestone and chert beds. The Formation is highly fractured and considered karstic (McKnight and Fischer, 1970). The Boone aquifer is hosted by the Boone Formation, which was dewatered during mining activities. Groundwater subsequently filled the mine voids when pumping ceased and has been shown to be highly contaminated with mobile AMD products (DeHay, 2003; DeHay et al., 2004; Playton et al., 1980). The geochemical and geological conditions present at the TCSS have raised concern that hazardous substances may be transported away from the TCSS via subsurface conduit flow. The Boone Formation outcrops in the eastern portion of Ottawa County, OK as well as most of Delaware County, OK, and supplies water to local springs (Miser, 1954). Contamination of springs and associated biota via groundwater is a major concern for local tribal members who use these natural resources for cultural and subsistence purposes (Garvin et al., 2009). Data regarding confirmation of groundwater transport of contaminants away from the TCSS are limited: several springs discharging from the Boone Formation have been observed to produce yellow-orange precipitates and watercress growing in spring water has been shown to contain elevated concentrations of toxic metals (Bridge and Garvin, 2014; Nairn, 2003). This project proposes to investigate the mechanisms and specific pathways by which metal transport may be occurring in the subsurface. Abundant wells, airshafts, mineshafts, and artesian springs at the site and downgradient offer opportunities to sample groundwater at various distances from the TCSS. This will allow for the construction of a hydrogeochemical model, which can be used to establish geochemical trends and evaluate metal loading to the surface environment as a result of metals released into groundwater at the TCSS. Additionally, we propose to determine the provenance of bioaccumulated lead in watercress by comparing lead isotope ratios of various source materials to affected plant tissue. The subsurface pathways of preferential transport in the study area will be mapped using electrical resistivity tomography, which will allow for detailed hydrogeophysical modeling of the subsurface related to the fracture patterns in the study area. Data gathered will be used to constrain existing models of the hydrologic properties of the Boone aquifer and simulate contaminant transport in the subsurface. A variety of software platforms will be used for this purpose, including; PHREEQC, MODFLOW 2005, and ArcGIS.