Abt Associates’ staff provided technical support to the U.S. Department of Justice (DOJ) regarding hydrogeology and water quality impacts at the Gilt Edge Mine Superfund Site in Lawrence County, S.D.

Abt staff reviewed and analyzed information from independent research and documents and data provided by the DOJ, visited sites, and participated in technical meetings and negotiations with the defendant.

We evaluated the:

• Hydrogeology and hydrology of the Gilt Edge Mine;
• Interaction between site features and vadose zone, groundwater, and surface water flow in the mine area; and
• Influence of remediation activities on water quantity and quality at the mine.

In addition, we assessed the sources of acid and heavy metal contamination at the Gilt Edge Mine, such as waste rock and fills, heap leach pads, historic tailings, sludge, underground workings, open pits, and pit lakes, and evaluated the transport of contaminants from source areas to groundwater and surface water in and near the mine.