Engineering & Mining Journal

JUL 2018

Engineering and Mining Journal - Whether the market is copper, gold, nickel, iron ore, lead/zinc, PGM, diamonds or other commodities, E&MJ takes the lead in projecting trends, following development and reporting on the most efficient operating pr

Issue link:

Contents of this Issue


Page 32 of 75

ENVIRONMENTAL MANAGEMENT JULY 2018 • E&MJ 31 reclamation projects in the region. Many of these reclamation projects were on ground never owned or operated by SGC. This agreement was memorialized in a Colorado District Court-approved Con- sent Decree, endorsed by the EPA, and approved by the BLM, with all regulators noting the benefit of the watershed ap- proach to the environment. SGC successfully completed all tasks called for by the Consent Decree and the Colorado Water Quality Division confirmed as much on February 26, 2003. "Each criterion in the termination assessment has been successfully accomplished. Therefore, the Division has concluded that there has been Successful Consent Decree Completion. In recognition of this reclamation, the Colorado Division of Minerals and Geology gave SGC its Reclamation Award for the work completed at the Mayflower mill and the Sunnyside mine, saying in an official letter "Congratulations to you and your organization for a job well done." In addition to the work summarized above, SGC has voluntarily participat- ed with the Animas River Stakeholders Group (ARSG) to evaluate and implement projects since 1994. Using their exper- tise as well as a number of State and Federal agencies, the group prioritized various contributing sources to the Upper Animas based on an analysis of factors such as the amount of each contaminant, physical attributes, accessibility to pow- er, and proximity to streams, wetlands, and avalanche paths. Eventually, 400 sites were identified as priorities. Further analysis revealed that 67 of these historic mining sources accounted for 90% of the metals con- tamination from all mining sources. This comprehensive prioritization approach proved successful and led the Colorado Department of Public Health and Envi- ronment (CDPHE) to implement 27 real- istic Total Maximum Daily Load standards based on partial remediation of the pri- ority sites. ARSG implemented many of these projects using 319 grants, and SGC expenditures and participation provided a portion of the in-kind match required under that program. SGC also provided a disposal area for one of the projects. SGC and ARSG were successful in re- moving 70% of the copper and 50% of the zinc in Mineral Creek. USGS analy- sis concluded that the "remediation pro- ject ... resulted in long-term reductions of the copper concentration and significant improvement in copper load in Mineral Creek. A similar reduction in zinc (and cadmium) concentrations is also evident." SGC's 30 years of remediation and rec- lamation substantially reduced ongoing metals loading in the Animas River from what would have otherwise been the case. Metals loading in the Animas River is the result of the geologic setting and more than a century of historic mining in the area. The Silverton Caldera is highly mineralized, and acid rock drainage and poor water quality in the area was always prevalent given the natural generation of significant quantities of heavy metals. There was also an extensive legacy of man-made, systematic, and cataclysmic discharges of metals and acidity to the Upper Animas River basin prior to 1985. It is incontrovertible that both SGC's five years of mining between 1986 and 1991, which used modern techniques and was under the modern era of environmental regulation, and SGC's 30 years of reme- diation and reclamation in the Silverton Caldera each substantially reduced met- als loading in the Animas River from what would have otherwise been the case. But for the actions of SGC, metals levels in the Animas River, and the resulting im- pacts on aquatic life, including the trout fishery downstream of Silverton, would undoubtedly be more adverse. Steven Lange is the director of the Geo- chemistry, Groundwater and Surface Water Group at Knight Piésold USA. He brings more than 40 years of experience related to investigation, evaluation, and remediation of mining and industrial sites throughout the world. He has conduct- ed baseline environmental studies, geo- chemical evaluations, ARD assessments, and geochemical modeling for feasibility, operational, closure, and remedial inves- tigation studies at mine sites around the world. He has been studying and evalu- ating mineral deposits in the San Juan Mountains of Colorado since 1976. This article was adapted from a technical pa- per he authored. The full version can be found at ports/miningandrec.pdf. Before and after: The Sunnyside Basin as it appeared in 1988 (left) shortly after SGC took over operations and how it appeared in 1996 after SGC's reclamation activities.

Articles in this issue

Links on this page

Archives of this issue

view archives of Engineering & Mining Journal - JUL 2018