WEST LITTLE SUGAR CREEK IS RECOVERING BUT STILL IMPACTED BY ACID DRAINAGE FROM THE ABANDONED GREEN VALLEY MINE IN SOUTHWEST INDIANA

Described as “some of the most contaminated water in Indiana” by the Department of Natural Resources (DNR), acidic drainage from the abandoned Green Valley Mine Site (northwest of Terre Haute, IN) has been impacting West Little Sugar Creek for over half a century. Although great improvements have been made as a result of the 1993-1994 DNR reclamation efforts, run-off from several seeps on site lead to elevated metal concentrations in water and sediments. This study assesses current water quality of the stream, with special emphasis on its evolution since remediation by comparison with Brake et al. (Env. Geo. v40 (2001) 1471-1481).

The impact of the site on West Little Sugar Creek (WLSC) was determined by regular sampling. During summer 2003, water samples were taken from on site, and from sites on WLSC upstream and downstream of the mine drainage. Values of pH were determined in the field and samples were acidified and refrigerated for later analysis. Iron (Fe) and aluminum (Al) concentrations were determined using standard quantitative spectroscopic methods. Other metal concentrations were determined using AAS. Sediment samples were taken at the same locations during fall 2002 and the beginning of summer 2003. Sediments were dried, coned and quartered, and mechanically sieved. The sediment fractions were leached using a sequential extraction technique adapted from Galán et al. (Appl. Geochem. v18 (2003) 409-421). The leachates were analyzed using the same methods performed on the field water samples.

Water samples from the site have high levels of Fe (10,000-15,000 mg/kg) and Al (4200-4600 mg/kg) and the pH is consistently below 4. Although metal and acidity decrease rapidly downstream from the confluence, concentrations remain elevated. A quarter mile downstream, pH is ~ 6.5, Fe is 50-80 mg/kg, and Al is 2 mg/kg. Three miles downstream pH is greater than 7, Fe is 0.8 mg/kg and Al is 0.2 mg/kg, all slightly elevated in comparison to WLSC upstream concentrations. Despite the reduced contaminant levels in the water, the area is degraded by significant iron precipitation in the steam channel and along the banks. We believe contaminants are mobilized with sediments during periods of high discharge, which carry metals further downstream.