Archived
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Location
Lexington, Kentucky
Start Date
7-5-2026 8:30 AM
End Date
7-5-2026 9:00 AM
Description
Dewatering of coal combustion residual (CCR) surface impoundments is a technically challenging item for sites with CCR units at closure. Generation has ceased at this site where fly ash was mostly sold for beneficial use and bottom ash was sluiced to composite-lined CCR surface impoundments to passively drain prior to landfilling. During site closure and restoration, bottom ash and relatively minor amounts of other permitted waste materials were consolidated into the site’s landfill and bottom ash impoundment. The bottom ash impoundment entered closure 5 years ago with installation of a final cover system and construction of a sump to allow continued removal of water from the saturated bottom ash in the impoundment. Initially, water was pumped from the sump via vacuum truck and transported for offsite disposal at a nearby permitted non-hazardous injection well. This method of dewatering was inefficient, and a three-dimensional flow model was created to evaluate the timeline for dewatering and to support design of an automated dewatering system. Initial modeling results will be presented, including calibration of the model based on observed dewatering conditions. The dewatering system design is based on the observed and modeled conditions and includes a submersible sump pump, surface tank, power, and instrumentation to allow more consistent filling of the tank since the sump pump operates intermittently based on sump water levels. Results from operation of the dewatering system will be presented, including the advantages and disadvantages of the system operating after one pumping season. Finally, the model was modified to evaluate how additional wells may help to more quickly dewater the impoundment and inform modifications to existing dewatering system infrastructure.
Document Type
Presentation
Archival?
Archival
Included in
Energy Systems Commons, Environmental Indicators and Impact Assessment Commons, Environmental Monitoring Commons, Mining Engineering Commons, Oil, Gas, and Energy Commons, Structural Materials Commons, Sustainability Commons
Dewatering System Operations and Modeling of a Bottom Ash CCR Surface Impoundment
Lexington, Kentucky
Dewatering of coal combustion residual (CCR) surface impoundments is a technically challenging item for sites with CCR units at closure. Generation has ceased at this site where fly ash was mostly sold for beneficial use and bottom ash was sluiced to composite-lined CCR surface impoundments to passively drain prior to landfilling. During site closure and restoration, bottom ash and relatively minor amounts of other permitted waste materials were consolidated into the site’s landfill and bottom ash impoundment. The bottom ash impoundment entered closure 5 years ago with installation of a final cover system and construction of a sump to allow continued removal of water from the saturated bottom ash in the impoundment. Initially, water was pumped from the sump via vacuum truck and transported for offsite disposal at a nearby permitted non-hazardous injection well. This method of dewatering was inefficient, and a three-dimensional flow model was created to evaluate the timeline for dewatering and to support design of an automated dewatering system. Initial modeling results will be presented, including calibration of the model based on observed dewatering conditions. The dewatering system design is based on the observed and modeled conditions and includes a submersible sump pump, surface tank, power, and instrumentation to allow more consistent filling of the tank since the sump pump operates intermittently based on sump water levels. Results from operation of the dewatering system will be presented, including the advantages and disadvantages of the system operating after one pumping season. Finally, the model was modified to evaluate how additional wells may help to more quickly dewater the impoundment and inform modifications to existing dewatering system infrastructure.
