TAR CREEK OKLAHOMA SUPERFUND SITE AND ITS MANY CHALLENGES

The Tar Creek Superfund Site is in Ottawa County, northeastern Oklahoma, near the Oklahoma/Kansas border. The site consists of approximately 43 square miles (27,520 acres) and is part of the Tri-State Mining District which includes parts of northeastern Oklahoma, southeastern Kansas, and southwestern Missouri. Five small mining communities, Picher, Cardin, Quapaw, Commerce, and North Miami are within the superfund site.

More than 2,500 acres are underlain by underground lead/zinc mines in the Oklahoma part of the Picher field. When the mines were abandoned in 1970, they filled with water. In 1979, acid mine water containing high concentrations of heavy metals began discharging into Tar Creek from natural springs, boreholes, and open mine shafts. In 1980, Governor Neigh of Oklahoma established a Tar Creek Task Force to investigate the drainage of acid mine water into Tar Creek. The Task Force requested the site be added to the National Priorities List in 1981; the site was listed in 1983. From 1984 to 1986, dikes were built to divert surface water around collapsed mine shafts and 88 abandoned deep wells were plugged to prevent migration of acid mine water into the Roubidoux aquifer.

Significant quantities of mill waste were generated by processing lead/zinc ores. The mill waste, chiefly composed of chert fragments 0.75 in. or less in diameter was referred to as “chat” by the miners. The chat was used for railroad ballast; a base for roads, parking lots, and concrete slabs; and concrete and asphalt aggregate. Studies by the Oklahoma Department of Environmental Quality and University of Oklahoma reported high concentrations of lead, zinc, and cadmium in the smaller particle sizes of chat. In 1995, U.S. Environmental Protection Agency began to remove chat from yards, streets, and dirveways in the five mining communities in response to elevated blood-lead levels in children.

In 2000, Governor Keating of Oklahoma created a task force to develop a comprehensive remediation plan for Tar Creek. In 2003, a plan was developed to include stream restoration, maximum chat utilization, land remediation and restoration, and mine-hazard attenuation. Some of the many challenges for the Tar Creek Superfund Site include size, legal issues, ownership, health and safety issues, data availability, land use, and the potential for subsidence.