An abandoned underground coal mine complex in southeastern Ohio was hydraulically sealed in 1980 by a 300-m long subsurface clay dike and mine-entry seals near the down-dip coal outcrop. Clay plugs also were emplaced in separate entries at a higher elevation than the dike. The intent was to flood the mine to decrease acid mine drainage. A few months after construction, an entry-seal clay plug blew out at an elevation corresponding to 85-90 percent inundation, and drains in natural materials supporting the dike began flowing, indicating leakage through or around the dike. Given these early setbacks, the objective of this study was to assess the sealing project after 20 years. Seasonally, inundation can reach 85-90 percent, but high water levels are transient because of leakage. Nevertheless, mine water chemistry indicates partial suppression of pyrite oxidation. Since sealing, mine water pH increased from 2.7 to 5.3, conductivity decreased from 2700 to 600 mu S/cm, and DO is <2 percent saturation. In a stream receiving the mine drainage, acidity and metals concentrations are highest at low flow due to release of stored mine water, but acid and metal loadings are lowest at those times. The improvement in water quality due to sealing is distinguished from annual variance or natural attenuation by using a nearby unsealed mine as a control. Factoring out pre-sealing differences between the two mines, decreases in acidity loading due to sealing are significant, and the sealing project has been beneficial.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.