Conceptual Flow and Transport Model – Uranium Plume near the Homestake Millsite March 2015

 Conceptual Flow and Transport Model – Uranium Plume near the Homestake Millsite 

SUMMARY 

The Homestake Mining Company’s (HMC) millsite at Grants, New Mexico, has been the source of many contaminants to the groundwater around the mill since 1961. Federal and state agencies recognized that seepage from HMC’s large tailings pile (LTP) had contaminated groundwater in subdivisions downgradient of the LTP with uranium (U) and selenium by the mid-1970s (EPA 2011). Groundwater transported U off of the millsite to subdivisions downgradient of the mill where concentrations reached many times current drinking water standards. This report presents a conceptual flow model (CFM) and conceptual transport model for groundwater flow and U transport in the groundwater basin near and upgradient of the LTP. The report tests the hypothesis that excess U found in groundwater beneath, southeast of, and northeast of the LTP are due simply to seepage from the LTP and that U entering the alluvium as discharge from the Middle San Mateo Creek basin has not reached the area around the LTP.

Read the full report # Myers FINAL hmc cftm report 031615