Archived
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Location
Lexington, Kentucky
Start Date
6-5-2026 2:30 PM
End Date
6-5-2026 3:00 PM
Description
Rainbow Energy Center’s (REC’s) Coal Creek Station manages process water in various engineered impoundments across the facility. As part of the ongoing life of the plant, one of the site process water ponds has been decommissioned to allow for construction of a new coal combustion residuals (CCR) impoundment within the same footprint. In order to transition from a non-CCR impoundment to construction of a CCR impoundment, the existing impoundment was closed and decommissioned in 2025. The composite-lined process water impoundment intended for closure previously operated from the early 1990s. To effectively close the impoundment, a closure verification plan was developed with the state environmental permitting agency to specify the requirements of closure and the plan to identify any areas of impact from past activities and allow for remedial action as part of the closure process. Background soil samples from upgradient of the site were collected and analyzed using state-approved methodology to develop site-specific background threshold values (BTVs) reflective of unimpacted conditions. The process water impoundment was initially closed by removing sediments, protective cover, and geomembrane liner (part of a composite liner system) from within the footprint. Following removal of the geomembrane liner, a detailed physical evaluation of the subgrade materials was conducted and included visual inspection and collection and analysis of soil samples. Results were analyzed to determine if subsurface soils had been impacted by the operation of the process water impoundment through comparison to the BTVs and to identify areas requiring additional removal of materials. Areas identified as impacted were excavated and additional confirmatory samples were collected and analyzed to verify removal.
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
Closure of a Process Water Impoundment
Lexington, Kentucky
Rainbow Energy Center’s (REC’s) Coal Creek Station manages process water in various engineered impoundments across the facility. As part of the ongoing life of the plant, one of the site process water ponds has been decommissioned to allow for construction of a new coal combustion residuals (CCR) impoundment within the same footprint. In order to transition from a non-CCR impoundment to construction of a CCR impoundment, the existing impoundment was closed and decommissioned in 2025. The composite-lined process water impoundment intended for closure previously operated from the early 1990s. To effectively close the impoundment, a closure verification plan was developed with the state environmental permitting agency to specify the requirements of closure and the plan to identify any areas of impact from past activities and allow for remedial action as part of the closure process. Background soil samples from upgradient of the site were collected and analyzed using state-approved methodology to develop site-specific background threshold values (BTVs) reflective of unimpacted conditions. The process water impoundment was initially closed by removing sediments, protective cover, and geomembrane liner (part of a composite liner system) from within the footprint. Following removal of the geomembrane liner, a detailed physical evaluation of the subgrade materials was conducted and included visual inspection and collection and analysis of soil samples. Results were analyzed to determine if subsurface soils had been impacted by the operation of the process water impoundment through comparison to the BTVs and to identify areas requiring additional removal of materials. Areas identified as impacted were excavated and additional confirmatory samples were collected and analyzed to verify removal.
