Abstract: The Tar Creek Superfund Site is a portion of the abandoned lead and zinc mining area known as the Tri-State Mining District (OK, KS and MO) and includes over 100 square kilometers of disturbed land surface and contaminated water resources in extreme northeastern Oklahoma. Underground mining from the 1890s through the 1960s degraded over 1000 surface hectares, and left nearly 50 km of tunnels, 165 million tons of processed mine waste materials (chat), 300 hectares of tailings impoundments and over 2600 open shafts and boreholes. Approximately 94 million cubic meters of contaminated water currently exist in underground voids. In 1979, metal-rich waters began to discharge into surface waters from natural springs, bore holes and mine shafts. Six communities are located within the boundaries of the Superfund site. Approximately 70% of the site is Native American owned. Subsidence and surface collapse hazards are of significant concern. The Tar Creek site was listed on the National Priorities List (NPL) in 1983 and currently receives a Hazard Ranking System score of 58.15, making Tar Creek the nation's number one NPL site. A 1993 Indian Health Service study demonstrated that 35% of children had blood lead levels above thresholds dangerous to human health. Recent remediation efforts have focused on excavation and replacement of contaminated residential areas. In January 2000, Governor Frank Keating's Tar Creek Task Force was created to take a “vital leadership role in identifying solutions and resources available to address” the myriad environmental problems. The principle final recommendation was the creation of a massive wetland and wildlife refuge to ecologically address health, safety, environmental, and aesthetic concerns. Additional interim measures included continuing the Task Force and subcommittees; study of mine drainage discharge and chat quality; construction of pilot treatment wetlands; mine shaft plugging; investigations of bioaccumulation issues; establishment of an authority to market and export chat, a local steering committee, and a GIS committee; and development of effective federal, state, tribal, and local partnerships.

Abstract: 400 systems installed within 4 years During the last two decades, the United States mining industry has greatly increased the amount it spends on pollution control. The application of biotechnology to mine water can reduce the industry's water treatment costs (estimated at over a million dollars a day) and improve water quality in streams and rivers adversely affected by acidic mine water draining from abandoned mines. Biological treatment of mine waste water is typically conducted in a series of small excavated ponds that resemble, in a superficial way, a small marsh area. The ponds are engineered to first facilitate bacterial oxidation of iron; ideally, the water then flows through a composted organic substrate that supports a population of sulfate-reducing bacteria. The latter process raises the pH. During the past four years, over 400 wetland water treatment systems have been built on mined lands as a result of research by the U.S. Bureau of Mines. In general, mine operators find that the wetlands reduce chemical treatment costs enough to repay the cost of wetland construction in less than a year. Actual rates of iron removal at field sites have been used to develop empirical sizing criteria based on iron loading and pH. If the pH is 6 or above, the wetland area (in2) required is equivalent to the iron. load (grams/day) divided by 10. Theis requirement doubles at a pH of 4 to 5. At a pH below 4, the iron load (grams/day) should be divided by 2 to estimate the area required (in2).