ACIDIC MINESPOIL RECLAMATION WITH AFBC BY-PRODUCT AND YARD-WASTE COMPOST

Abstract

Economic and environmental incentives to reduce solid waste volumes have spurred interest in the development of beneficial uses for urban and industrial by-products. This project investigated the reclamation efficacy and impacts on soil and water quality of two such materials: atmospheric fluidized bed combustion (AFBC) by-product and yard-waste compost. Six 1-acre watersheds were constructed on acidic abandoned mined land spoil (pH range 3.5 to 4.5) Two watersheds each were then reclaimed with 8 in of borrow soil, 125 tons/acre of AFBC, or 125 tons/acre of AFBC and 50 tons/acre of compost, and planted with a grass-legume seed mix. Watersheds were instrumented to record hydrographs of storm-water runoff events, measure erosion, and collect samples of surface- and percolate-water flow. One year after reclamation the AFBC and AFBC+ compost treatments compared favorably with the traditional resoil reclamation practice. Spoil pH in the 0 to 4 in depth was increased to the range 6 to 8 which was similar to the resoil pH, and complete vegetative cover was successfully established on all watersheds. However, plant biomass production was approximately 2 times larger on the resoiled watersheds than on the amended spoil. Consequently, erosion was smallest on the resoiled watersheds. All three reclamation treatmentsmore » increased runoff water pH to >7 and decreased soluble Al. Concentrations of Ca and S were larger in runoff- and percolate-water samples from AFBC-treated watersheds than from the resoiled watersheds. Trace element concentrations in all water samples remained very low and showed almost no treatment effects.« less