The U.S. Geological Survey, in cooperation with the Tennessee Department of Transportation, conducted an investigation of acid-rock drainage from road cuts in Tennessee during 2014-2015. The Devonian Chattanooga Shale contains disseminated pyrite and is a primary producer of acid-rock drainage (ARD) in Tennessee. One objective of the overall investigation was to attenuate ARD by manipulating the indigenous microbial community through different treatment injections. The scope of the study included establishing flow-through microcosms constructed with shale from the Chattanooga Shale formation rich in pyrite collected from an ARD site in Middle Tennessee. The microcosms were subjected to various treatments and evaluations included monitoring pH and additional geochemical and microbial constituents in the effluent waters.