Mining-Influenced Water from the Abandoned Hausham Colliery in Southern Germany—A Case of Unmonitored Natural Attenuation

Coal mining in Upper Bavaria ended in the 1960s and the mines were flooded. This study investigates the mining-influenced water and its environmental implications in the Hausham Mine, one of many unmonitored coal mines in the region and along the northern edge of the Molasse zone in Austria, Germany and Switzerland. Water and solid samples were collected in the vicinity of the discharge area within a waste rock pile and downstream of a nearby lake. The samples were subjected to chemical and isotopic analysis, with a focus on the potential for natural attenuation. The mine waste discharge has high initial concentrations of calcium, sulfate, and iron, and elevated concentrations of nickel, zinc, and strontium. These element concentrations are significantly reduced along the flow path so that the water is environmentally safe for discharge into the Loidlsee. The reduced contaminant levels are related to the formation of secondary iron precipitates and associated sorption processes, the formation of secondary calcium carbonates, and mixing with another groundwater source. The results indicate that the carbonate-dominated sediments of the Molasse zone contribute substantially to the natural remediation of a potential environmental problem.