Fig 1.

Layout of the experimental plots at the Old Rifle uranium mill tailings site. Each plot had 5 injection wells (open circles) perpendicular to groundwater flow, 4 monitoring wells (filled circles) down-gradient of acetate injection, and 1 monitoring well positioned up-gradient of the injection wells (filled triangle). The 2004 experimental plot was maintained under Fe-reducing conditions, and the 2005 experimental plot was driven to sulfate-reducing conditions by using different durations of biostimulation.