Archived
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Location
Lexington, Kentucky
Start Date
6-5-2026 2:00 PM
End Date
6-5-2026 2:30 PM
Description
When closing a CCR Impoundment while leaving CCR in place, 40 CFR 257.102 requires minimizing post-closure infiltration of liquid into the CCR. This presentation will provide a description of a closure plan for a 16-acre impoundment in Indiana to accomplish this criteria. Key components of the closure plan which will be presented including consolidation of CCR into a smaller footprint due to questionable underlying clay layer identified in a portion of the impoundment and the design of a geosynthetic and soil cap system. A Soil-Cement-Bentonite (SCB) cutoff wall will be constructed to enclose the portion of the impoundment where CCR material will remain in place and closure will occur through a cap and cover system. The cutoff wall was specified to meet the requirements of the Indiana Department of Environmental Management (IDEM) guidance document Engineering Control: Slurry Walls (May 2021). The cutoff wall was designed to penetrate through a sand layer underlying the CCR to key into a lower clayey material to seal off the CCR material from surrounding groundwater. Piezometers were designed inside and outside the closed impoundment to monitor water levels and verify a negative gradient per IDEM standards. An extraction well system was designed to dewater the CCR to meet the performance standard requiring elimination of free liquids. Water pumped from the impoundment will be pretreated, if required, and then discharged to a municipal sewer system.
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
CCR Impoundment Closure: Encapsulation Design Using Closure Cap and Cutoff Wall
Lexington, Kentucky
When closing a CCR Impoundment while leaving CCR in place, 40 CFR 257.102 requires minimizing post-closure infiltration of liquid into the CCR. This presentation will provide a description of a closure plan for a 16-acre impoundment in Indiana to accomplish this criteria. Key components of the closure plan which will be presented including consolidation of CCR into a smaller footprint due to questionable underlying clay layer identified in a portion of the impoundment and the design of a geosynthetic and soil cap system. A Soil-Cement-Bentonite (SCB) cutoff wall will be constructed to enclose the portion of the impoundment where CCR material will remain in place and closure will occur through a cap and cover system. The cutoff wall was specified to meet the requirements of the Indiana Department of Environmental Management (IDEM) guidance document Engineering Control: Slurry Walls (May 2021). The cutoff wall was designed to penetrate through a sand layer underlying the CCR to key into a lower clayey material to seal off the CCR material from surrounding groundwater. Piezometers were designed inside and outside the closed impoundment to monitor water levels and verify a negative gradient per IDEM standards. An extraction well system was designed to dewater the CCR to meet the performance standard requiring elimination of free liquids. Water pumped from the impoundment will be pretreated, if required, and then discharged to a municipal sewer system.
