A well-developed fluviokarst in central Tennessee that has been contaminated with acidic drainage provided a natural laboratory for the study of the interaction of acid mine drainage with carbonate rocks and by analog, the disposal of acidic metal-bearing wastes in karst terranes. The East Fork of the Obey River, a tributary of the Cumberland River, drains a 523 km2 basin along the western margin of the Cumberland Plateau. The upper basin lies on clastic rocks which include coals mined earlier in this century. The lower basin is highly karstified. The main stem of the Obey River and all of its tributaries follow underground routes in the lower basin. This study is concerned with the 9 km underground course of the East Fork from its swallet to its rise, and with a major infeeding tributary that is highly contaminated by acid mine drainage. Acid mine water chemistry persists through the conduit system so that the spring waters contain substantial iron and aluminum and have pH values as low as 4.2. Although neutralization of acid water does take place in the karst system, even an 8 km reach of conduit is not sufficient to take the process to completion. Fast moving water within karst conduits, relatively sluggish reaction kinetics, and a natural armoring of the conduit walls by the precipitation of iron compounds all conspire to make the neutralization of acidity in karst systems a relatively inefficient process.

Full reference:
Sasowsky, I.D., White, W.B., and Webb, J.A., 1995, Acid mine drainage in karst terranes: Geochemical considerations and field observations, in: Beck, B.F. (ed.), Karst Geohazards - Engineering and environmental problems in karst terrane - Proceedings of the Fifth Multidisciplinary Conference on Sinkholes and the engineering and environmental impacts of karst, A.A. Balkema, Rotterdam, p.241-247.