Using Tracers to Understand the Hydrology of an Abandoned Underground Coal Mine

Abstract

Flooded underground mines pose a difficult problem for remediation efforts requiring hydrologic information. Mine environments are hydraulically complicated due to sinuous travel paths and variable hydraulic gradients. For an acidic mine remediation project, conducted by the University of Oklahoma in conjunction with the Oklahoma Conservation Commission, a tracer study was undertaken to identify basic hydrologic properties of a flooded coal mine. The study was conducted to investigate the possibility of in-situ remediation of acidic mine water with the use of alkaline coal combustion by-products. Information on the rate of flow and "connectiveness" of injection wells with the discharge point was needed to develop a treatment strategy. Fluorescent dyes are not typically used in mine tracer studies because of the low pH values associated with certain mines and a tendency to adsorb ferric iron precipitates. However, Rhodamine WT was used in one tracer test because it can be detected at low concentrations. Due to poor recovery, a second tracer test was undertaken using a more conservative tracer-chloride. Each tracer produced similar travel time results. Findings from this study suggest that Rhodamine WT can be used under slightly acidic conditions, with mixed results. The more conservative tracer provided somewhat better results, but recovery was still poor. Use of these tracers has provided some valuable information with regard to mine hydrology, but additional questions have been raised.

The Use of Coal Combustion by-Products for in Situ Treatment of Acid Mine Drainage

“…Tracer studies conducted in 1996 and 1997 (Canty and Everett, 1998d) confirmed that there was a hydrologic connection between the discharge point and the injection wells. Also, the tests indicated that there was a relatively fast breakthrough time.…”

“…The actual treatment area is difficult to determine given the nature of the mine environment and the uncertainty associated with the distribution of the material. Tracer studies were conducted in the mine to confirm connectivity between the wells and the discharge point (Canty and Everett, 1998d).…”

Injection of Fluidized Bed Combustion Ash into Mine Workings for Treatment of Acid Mine Drainage

“…Tracer studies with fluorescent and chlorine tracers indicated that the injection wells were hydraulically connected to the mine seep (Canty and Everett 1998b). However, the studies also indicated that much of the tracer material remained in the mine, which suggested that AIT could be successfully employed at the site.…”

Water Management at Abandoned Flooded Underground Mines

“…• assessing the risk or cause of mine water inrushes/inundations (Skowronek and Zmij 1977;Goldbrunner et al 1982;Wittrup et al 1986;Qiang et al 1992;Lachmar 1994); • optimising mining strategy (Adelman et al 1960;Reznik 1990;Williams and Kirschner 1992;Kirschner and Williams 1993); • evaluating the feasibility or effects of underground disposal of non-radioactive waste (Fried 1972;Himmelsbach and Wendland 1999); • evaluating potential underground disposal of radioactive waste (Abelin and Birgersson 1985;Brewitz et al 1985;Galloway and Erickson 1985;Cacas et al 1990;Lewis 1990;Birgersson et al 1992;Hoehn et al 1998;Sawada et al 2000; hundreds of studies were conducted in the Stripa mine/Sweden, the Grimsel/Switzerland experimental site, and the Yucca Mountain/USA site); • subsidence studies (Mather et al 1969); and • developing remediation strategies (Aldous and Smart 1987;Doornbos 1989;Hawkins 1993, 1994;Davis 1994aDavis , 1994bWolkersdorfer 1996;Wolkersdorfer et al 1997a;Canty and Everett 1998) Tracer tests have also been conducted to study "heat mining" in geothermal projects (e.g. Gulati et al 1978;Horne et al 1987;Kwakwa 1989;Randall et al 1990;Aquilina et al 1998).…”