English

Abstract

In 1996 the Ohio Department of Natural Resources (ODNR) along with state, local, government agencies, and citizen's group formed the Huff Run Watershed Restoration Partnership, Inc. (HRWRP) to clean up the poor water quality in the Huff Run Watershed. The Lindentree and Lyons passive treatment systems were designed and installed with the use of steel slag to produce several hundred times more alkalinity per equal volume as compared to limestone to help treat the acid mine drainage (AMD) in the watershed due to years of unregulated surface and deep mining. The Huff Run Watershed is located in Mineral City, Tuscarawas County, Ohio. The primary goals for any of the projects in the Huff Run Watershed are: the reclamation of toxic mine spoil and exposed coal refuse, drain existing acidic impoundments with alkaline treatment of AMD during dewatering and thereby eliminating the main sources of AMD seepages; constructing grass-lined and alkaline rock (limestone riprap and steel slag) channels for collection and diversion of surface water; construction of alkaline rock channels followed by settling ponds and aerobic wetlands as part of the passive treatment system for future AMD seepages; and restoration of the existing central main drainage channel. Both projects encompass 33.6 acres of the watershed and utilized steel slag to supersaturate relatively good water to neutralize low pH waters. Post-construction monitoring for the Lindentree and Lyons projects was conducted in years 2003 and 2005, respectively. Steel slag is a co-product from the making of steel. The melting process creates an amorphous glassy solid matrix where the oxides are encased in calcium-aluminate- silicates. This glassy matrix is soluble and has a high neutralization capacity for acid mine drainage. Once the steel slag is soluble, the pHs of the dissolved fluids ranges from 10 to 11. Combining these flows with pHs in the ranges of 3 and 4 is showing a net alkalinity going into the Huff Run Watershed. As steel slag does not armor over like limestone, it is expected to provide a long term source of alkalinity. Site discharges from both the Lindentree and Lyons projects have been net-alkaline, providing a buffer to acidic conditions currently found in the lower reaches of the Huff Run Watershed. The Lindentree, Lyons, and other ODNR projects, should provide a better understanding of the use of steel slag in future AMD remediation projects in the future.