“Evidence for Ground Water Circulation in the Brine‐Filled Aquitard, Oak Ridge, Tennessee” by Ronit Nativ, Amy Halleran, and Arnold Hunley

Abstract

The question addressed by Nativ et al. (1997), whether or not circulation exists between the deep ground water system and the shallow contaminated ground water underlying the waste disposal areas of the Oak Ridge Reservation (ORR), is indeed important. The answer to this question impacts not only the potential for transport of contaminants offsite via deep ground water pathways, but also the extent and associated cost of ground water monitoring. While Nativ et al. conclude that the saline water contained at depth is not isolated and that confined water (and dissolved solutes) move along open conduits at relatively high velocity into adjacent, more permeable units, the authors of this discussion would argue that when the entire body of evidence is examined, the results are inconclusive and the interpretation proposed is but one of several that could account for the apparently conflicting observations. Further, those data that suggest possible communication between the deep and shallow ground water systems also support the conclusion that the flux of ground water exchanged between systems is likely to be very small and transport times very large, thus mitigating the effects of any contamination introduced into the deep system by either natural or anthropogenic causes.