INFLUENCE OF FLY ASH , TOPSOIL , LIME , AND ROCK ‐ P ON ACID MINE DRAINAGE FROM COAL REFUSE 1 by Meral L . Jackson

Most Appalachian coal refuse materials contain significant amounts of pyritic S and are likely to produce acid mine drainage (AMD). A column technique was designed and implemented to evaluate the effects of various AMD mitigation treatments including fly ash, topsoil, lime, and rock‐P. Two types of fly ash were tested, one at four rates of application, the other at two rates. Conventional lime plus topsoil, lime without topsoil, topsoil only, topsoil with fly ash, rock‐P, rock‐P plus topsoil, and rock‐P plus fly ash were also evaluated and compared with pure refuse controls. The drainage from the unamended columns rapidly dropped to less than pH 2 with very high levels of Fe, Mn, and S. Alkaline fly ash dramatically reduced drainage Fe concentrations as well as Mn and S when compared with untreated refuse. The lime treatments also improved the drainage Fe, Mn, and S concentrations. The rock‐P treatment initially reduced Fe, Mn, and S, but eventually lost its mitigation capability. Leachate B concentrations were initially high for some of the ash columns, but decreased over time, while the unamended refuse B levels increased with time. Combined treatments of phosphate/ash, ash/topsoil, and pure refuse with topsoil were intermediate between the pure ash treatments and unamended refuse in drainage quality. With further analysis, fly ash may prove to be a viable alternative to conventional topsoiling/lime treatments to ameliorate AMD if adequate alkalinity is present in the ash/refuse mixture. If fly ash alkalinity is inadequate to balance potential acidity, accelerated leaching of ash bound metals may occur. Additional