Use of flue gas desulfurization by-product for mine sealing and abatement of acid mine drainage

Broken Aro mine is an abandoned underground mine complex last mined in 1910. Acid mine drainage (AMD) from the mine has negatively impacted the water quality in Simmons Run. Re-mining of Broken Aro allowed for recovery of an energy reserve, exposure of the AMD source, de-watering of the mine complex, and simple placement of a continuous mine seal. The fixated FGD scrubber by-product was chosen as the material for mine seal construction due to its low hydraulic conductivity and high alkalinity. The final seal was approximately 2600 ft long, 15 ft wide and was installed in two 4–6 ft compacted lifts for a total height of 8–12 ft. The seal was constructed concurrent with mining activities to maintain a continuous hydraulic barrier. The seal has retained water inside the mine complex and has decreased the contaminant loads to Simmons Run.