Superfund Site: GILT EDGE MINE
LEAD, SD

Superfund Site Profile

EPA has completed the third five-year review of remedy implementation and performance at the site.

The five-year review concluded that the remedy at OU1 is expected to be protective of human health and the environment upon completion. In the interim, remedial activities completed to date have adequately addressed all exposure pathways that could result in unacceptable risks in these areas.

The interim remedy at OU2 is not protective because of the following issue: the numeric value for the chronic cadmium standard for aquatic life is periodically exceeded in surface water.

The following actions need to be taken: evaluate this issue during the OU2 remedial investigation and feasibility study, after the OU1 remedy has been implemented to ensure protectiveness.

The interim remedy at OU3 currently protects human health and the environment because there are currently no completed exposure pathways. However, in order for the remedy to be protective in the long term, the following actions need to be taken: Ruby Repository needs land use restrictions formalized in a decision document and implemented to ensure protectiveness.

The next five-year review is required by June 2022.

The 2017 five-year review report is available for download:
Or can be viewed at the information repository:
  • Phoebe Apperson Hearst Public Library
    315 Main Street
    Lead, South Dakota 57754
    (605) 584-2013

SITE BACKGROUND

The 360-acre Gilt Edge Mine site is located about 6.5 miles east of Lead, South Dakota. The primary mine disturbance area encompasses a former open pit and a cyanide heap-leach gold mine, as well as prior mine exploration activities from various companies. In the late 1990s, the most recent mine operator, Brohm Mining Company (BMC), left about 150 million gallons of acidic heavy-metal-laden water in three open pits and millions of cubic yards of acid-generating waste rock. Historical operations at the site contaminated surface water and leachate with hazardous chemicals. Investigation and cleanup activities at the site are ongoing. Interim remedies are currently in place for two of the site’s three areas.