Impact of Coal Mine Reclamation Using Coal Combustion By-products on Groundwater Quality: Two Case Studies
Impact of Coal Mine Reclamation Using Coal Combustion By-products on Groundwater Quality: Two Case Studies
Presented on Wednesday, March 18, 2015
In this study, the impact of coal mine reclamation using flue gas desulfurization (FGD)materials on the water qualities of the upper-most aquifer systems underlying tworeclamation sites is investigated. FGD materials are referred to the synthetic gypsum and stabilized calcium sulfite by-product produced from the sulfur dioxide emissioncontrol process of coal combustion power generation utility. The two ongoing, full-scalecoal mine reclamation projects, Conesville Five Points and Cardinal Star Ridge, of varying constructability scales and fill material combination started in 2009 to demonstrate high-volume usage of FGD materials. The total amounts of FGD by-products to be placed at the Conesville Five Points and Cardinal Star Ridge demonstration sites are estimated to be about one million and half million tons, respectively. To evaluate the impact, groundwater and surface water around the reclamation sites are collected on a monthly or quarterly basis and analyzed for 34parameters/constituents. For both sites, over eighteen-month worth of data were collected before reclamation began and used to establish background water qualitylevels. The impact of the reclamation on the water qualities are evaluated by the data collected from more than two years of monitoring since the reclamation began. It was found that the effects of reclamation activities on the water qualities at both sites are statistically significant. The concentrations of a number of monitoring parameters and constituents, such as calcium, sulfate, thallium, and manganese, have increased andexceeded the background levels in one or more of the sampling locations since the reclamation began. In addition, incline or decline trends of a number of major monitoringparameters/constituents are also identified in more than one sampling locations at both sites. However, the observed impacts are unlikely from the leachate of the backfilled FGD materials. It is plausible that the reclamation activities have altered the hydrogeological conditions of the underlying aquifers and varied the extent of thehydrogeochemical processes. The optimal sampling frequencies of both sites are also evaluated.