New Mexico Geological Society Annual Spring Meeting — Abstracts

The toxic spill generated by the Gold King Mine (GKM) blowout north of Silverton, Colorado traveled ~60 river miles along the Animas River and reached the City of Durango by 8:00pm on August 6, 2015 carrying elevated levels of heavy metals as both dissolved load and colloids. On August 15, 2015, the EPA determined, based on on-going analyses of river samples that the water quality of the Animas River had returned to pre-spill levels. Contaminated water and colloid samples were collected by the authors using standard EPA protocol during peak spill and toxicity levels, from August 7-13, 2015. Water samples from six Animas River locations and sludge samples from eight river and canal locations, were independently analyzed at an EPA and State of Colorado Certified Laboratory with funding provided by Fort Lewis College (FLC) Provost Barbara Morris. Nine undergraduate geology majors, as part of an upper-level undergraduate Geology course, were charged with undertaking a comparative geochemical analysis of water quality data collected by the EPA and the Geosciences Department at FLC. Each student was assigned specific tasks; all students collaborated and worked together to produce a final PowerPoint® presentation. The students addressed the geologic setting of the Silverton Caldera, mining history, historic mine releases, water quality concerns, bulkhead construction and benefits, and generated suitable GIS maps. Field outings to the Silverton area were conducted in August to discuss and geochemically distinguish between AMD and ARD sites. Historic cross-sections and high wall plans of the GKM were graciously provided by the Colorado Division of Reclamation, Mining, and Safety (Abandoned Mines Division). Spatially-referenced data from ArcMap® was imported into Vulcan® (Maptek) software, and a 3D model of the GKM underground workings was generated: (1) to illustrate the geologic and hydrologic complexity of the mine; and, (2) to investigate possible hydrologic connectivity that could possibly explain the elevated flow volumes observed during the blowout. In addition to the educational benefits of the study, the goals of the study were to provide the public with a more complete understanding of the GKM, and help explain why metal concentrations in streams vary by sample location, discharge levels, and time of day. The students presented their work at public forums.