Hydrology and Water Quality Associated With The Midwestern Reclamation Site (Site No. 1087), Pike County, Indiana

Final Report from the Indiana Geological Survey to the Indiana Division of Reclamation

The Midwestern Site (No. 1087), Pike County, Indiana, was selected as a demonstration project where coal combustion byproducts (CCBs) would be utilized as part of reclamation.
CCBs, including ash and fixated scrubber sludge (FSS), were used as structural fill and capping materials.
The Indiana Geological Survey (IGS) and Indiana University (IU) were contracted to monitor hydrology.
This reclamation approach that utilizes CCBs has favorably altered the hydrologic and hydrochemical conditions on the site in such a way that rain water has a shorter residence time and is less exposed to acid-generating conditions. This has been achieved without any significant leaching of detrimental trace elements from the CCBs.

Compared with pre-reclamation conditions:

Total acidic outfall from the site experienced a five-fold reduction.
Direct surface runoff from the site has increased, but this has not caused any increased erosion.
Sufficient moisture is being retained in the soil cover to insure healthy vegetation.
Storm runoff is more dilute than baseflow.
Concentrations of iron and aluminum in outflow from the site have also decreased by a factor of five.

Under post-reclamation conditions:

Baseflow is being effectively treated by a passive anoxic limestone drain (PALD).
The preexisting contaminant plume is being effectively isolated from vertical recharge by the CCB cap.
Elements leached from the CCBs include potassium, chloride, boron, molybdenum, and arsenic. Higher concentrations of these elements occur in ground water at shallow depths beneath the FSS cap.
Trace elements leached from CCBs have been observed in stream flow at the site's outlet. However, their concentrations are far below those observed in ground water on the site, and most have levels that are at, or near, detection limits. Therefore, such values are only approximate estimates and can not be taken as an indication of the actual concentrations of trace elements in the stream flow; indeed, there is a statistical probability that some of these values are not different from zero.