Plan for Injection of Coal Combustion Byproducts Into the Omega Mine for the Reduction of Acid Mine Dra1nage

Abstract

The Omega Mine Complex is located outside of Morgantown, West Virginia. The mine is in the Upper Freeport Coal, an acid-producing coal seam. The coal was mined in a manner that has resulted in acid mine drainage (AMO) discharges at multiple points. During the 1990's, the West Virginia Division of Environmental Protection (WVDEP) assumed responsibility for operating a collection and treatment system for the AMO. Collection and treatment costs are approximately $300,000 per year. An innovative procedure of injecting grout into the mine workings to reduce AMO and the resulting treatment costs is proposed. The procedure involves injecting grout mixes composed primarily of coal combustion byproducts (CCB's) and water, with a small quantity of cement. The intention of the injection program is to fill the mine voids in the north lobe of the Omega Mine (an area where most of the acidity is believed to be generated) with the grout, thus reducing the contact of air and water with potentially acidic material. The grout mix design consists of an approximate 1 : 1 ratio of fly ash to byproducts from fluidized bed combustion. Approximately 100 gallons of water per cubic yard of grout is used to help achieve flowability. Observation of the mine workings via subsurface borings and downhole video camera operation confirmed that first-mined areas were generally open while second-mined areas were generally partially collapsed. The injection program was developed to account for this by utilizing closer injection hole spacing in second-mined areas. The construction documents have been prepared, and the project is expected to be bid in 1997. The engineer's cost estimate is approximately $2,500,000. Administration of a construction contract for the project is ongoing through WVDEP's Abandoned Mine Lands (AML) program. Funding for the project is coming from the WVDEP; Allegheny Power; Consol, Inc.; United States Office of Surface Mining Reclamation and Enforcement (OSMRE); Anker Energy Corporation; and the Electric Power Research Institute.