On April 15, 2016, the U.S. Environmental Protection Agency (EPA) announced that the Agency and the state of South Dakota reached agreement with Coca Mines, Inc., and Thomas Congdon to settle their respective liabilities at the Gilt Edge Mine Superfund Site by making a payment of just over $10 million.

The site encompasses a former open pit and a cyanide heap-leach gold mine, and was used for hard rock mining since the late 1800s. It was extensively disturbed by mining and mineral processing operations. The primary mine operator abandoned the site, leaving mining features such as open pit lakes with high walls of exposed mineralized bedrock, underground mine workings, and acres of waste rock, spent ore, and tailings. Exposure to the sulfide-containing materials to air and oxygen generates approximately 95 million gallons of acid rock drainage every year. The money recovered will help pay for the cleanup, alleviating the taxpayer burden.

On this page:

• Information about the companies
• Information about the Gilt Edge Mine Site
• Overview of the consent decree
• Contact information

Information about the companies

CoCa Mines, Inc. acquires, explores for, develops, mines and processes gold and silver ore. The Company holds interests in properties throughout the United States and Company. Helca Limited is CoCa’s parent company.

Thomas Congdon was President and Chief Executive Officer of CoCa. He also was a shareholder, and served as both general and limited partner of Congdon and Carey Ltd. No 5 and Congdon and Carey Ltd. No. 5, both predecessors in interest to CoCa.

Information about the Gilt Edge Mine Site

The 360-acre Gilt Edge Mine site is located 6.5 miles east of Lead, SD. Historic mining activities created acid rock drainage, which impacts the headwaters of Strawberry Creek and Ruby Gulch, which are tributaries to Bear Butte Creek. They are classified by South Dakota water quality standards as irrigation, fish and wildlife, recreation, and stock watering waters. Contaminants of concern include cadmium, arsenic, copper, lead, selenium, thallium, and zinc. More information can be found on the Gilt Edge Mine site profile sheet.

Overview of the consent decree

The consent decree for recovery of past response costs provides for a lump sum payment for the Agency’s past cleanup costs at the site and requires Coca to pursue various insurance claims. Upon recovery of any insurance claim, Coca is required to pay a portion of the claim to both the United States, and the state of South Dakota. South Dakota also received a portion of the lump sum payment. The consent decree was entered on September 19, 2016 in the District of South Dakota Western Division United States District Court.

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Contact information

For more information, contact

Amelia Piggott
Enforcement Attorney
303-312-6410
Piggott.amelia@Epa.gov

Joy Jenkins
Remedial Project Manager
303-312-6873
Jenkins.joy@epa.gov

U.S. Environmental Protection Agency
Region 8
1595 Wynkoop Street
Denver, CO 80202-1129

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