Mine Water Discharge Management: Inactive Oil Shale Mine
Garfield County, Colorado
WWL is conducting closure activities for a former oil shale mine in western Colorado. Mine water chemistry and discharge monitoring and management is a major component of our closure responsibilities. Groundwater discharges from the mine as “retort water” and as “mine water”. Retort water refers to groundwater that has come in contact with the underground retorts (large chambers used for retort testing), and “mine water” refers to groundwater discharging from portions of the mine workings in which retorting had not been performed. The retort water contains elevated concentrations of certain organic constituents and is managed onsite through evaporation. Until recently, the mine water discharged under a Colorado Discharge Permit System permit; WWL successfully terminated the permit with the approvals of the Colorado Department of Public Health and Environment and Colorado Division of Reclamation, Mining, and Safety. The permit termination effort was supported by a significant amount of water chemistry data and related interpretation of mine water and downgradient groundwater collected over several years. WWL performs semi-annual sampling at the mine to monitor for water chemistry trends in both the retort and mine waters.
WWL conducted underground hydrologic reconnaissance and sampling of underground wells to assess potential impact of former operations to underlying aquifers. To assess natural groundwater quality at the mine, samples were collected from springs located upgradient and cross-gradient of the mine workings. The analytical program for the characterization efforts was developed based on our knowledge of the geochemical character of the host formation and the constituents commonly associated with oil shale retorting operations. The analytical results were used to demonstrate that water quality in the underlying aquifer had not been impacted by mine operations.
Management of retort water discharging from the mine is one of the greatest challenges for ultimate closure of the mine. WWL has evaluated treatment options for the retort water including construction and testing of a passive bioreactor cell and are currently evaluating the feasibility of alternative management options for the retort water, including capture and diversion of groundwater by drilling network of boreholes, contaminant source removal, bioremediation, grout seals, underground injection, and natural attenuation to avoid the long-term operation and maintenance.
Garfield County, Colorado
WWL is conducting closure activities for a former oil shale mine in western Colorado. Mine water chemistry and discharge monitoring and management is a major component of our closure responsibilities. Groundwater discharges from the mine as “retort water” and as “mine water”. Retort water refers to groundwater that has come in contact with the underground retorts (large chambers used for retort testing), and “mine water” refers to groundwater discharging from portions of the mine workings in which retorting had not been performed. The retort water contains elevated concentrations of certain organic constituents and is managed onsite through evaporation. Until recently, the mine water discharged under a Colorado Discharge Permit System permit; WWL successfully terminated the permit with the approvals of the Colorado Department of Public Health and Environment and Colorado Division of Reclamation, Mining, and Safety. The permit termination effort was supported by a significant amount of water chemistry data and related interpretation of mine water and downgradient groundwater collected over several years. WWL performs semi-annual sampling at the mine to monitor for water chemistry trends in both the retort and mine waters.
WWL conducted underground hydrologic reconnaissance and sampling of underground wells to assess potential impact of former operations to underlying aquifers. To assess natural groundwater quality at the mine, samples were collected from springs located upgradient and cross-gradient of the mine workings. The analytical program for the characterization efforts was developed based on our knowledge of the geochemical character of the host formation and the constituents commonly associated with oil shale retorting operations. The analytical results were used to demonstrate that water quality in the underlying aquifer had not been impacted by mine operations.
Management of retort water discharging from the mine is one of the greatest challenges for ultimate closure of the mine. WWL has evaluated treatment options for the retort water including construction and testing of a passive bioreactor cell and are currently evaluating the feasibility of alternative management options for the retort water, including capture and diversion of groundwater by drilling network of boreholes, contaminant source removal, bioremediation, grout seals, underground injection, and natural attenuation to avoid the long-term operation and maintenance.