Coal mining waste management and its impact on the groundwater chemical status exemplified in the Upper Silesia Coal Basin (Poland)

Sulfidic coal mining wastes constitute one of the the major global bulk waste stream and are extensively reused in engineering constructions. Occurrence in the waste rock of geochemically instable sulfides results in A/NRD (Acid/Neutral Rock Drainage) that makes this material environmentally problematic. The paper is focused on the impact assessment of coal mining waste management practices exemplified in different objects (coal mining waste dumps) and different waste management methods (residual coal extraction, embankment construction, ground leveling and using as a structural fill of a waterlogged quarry) on chemical status of groundwater. Long-term groundwater monitoring data in the vicinity of three dumping sites and the analysis of pore solutions extracted along the vertical profiles of the waste layers of different ARD generation potential shows that high sulfate salinity, which resulted from sulfide oxidation, is the major long-term source of strong groundwater deterioration caused both by ARD and NRD. Abundant constituents released by ARD are Mn and in anoxic groundwater environment also Fe. The results show the need of application of groundwater protection measures both with respect to ARD and NRD generating coal mining waste.