Archived
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Location
Lexington, Kentucky
Start Date
6-5-2026 1:30 PM
End Date
6-5-2026 2:00 PM
Description
This session describes a coordinated multi-year effort to assess and manage groundwater quality at five CCR impoundments. The objectives were to (i) develop site-specific hydrogeologic and geochemical conceptual models; (ii) quantify groundwater flow and constituent transport under baseline and post-closure conditions; and (iii) design and evaluate corrective action strategies that achieve regulatory compliance and provide a defensible framework for long-term monitoring and management. The program highlights a phased approach aligned with regulatory requirements, progressing from closure construction to corrective action planning for detected exceedances. Comprehensive hydrogeologic datasets including borehole lithology, hydraulic testing, CCR source water characterization, and groundwater monitoring were assembled. Numerical and analytical modeling tools were applied: HELP for infiltration simulation, MODFLOW for three-dimensional flow, MT3DMS and MODPATH for advective-dispersive transport and plume migration, and PHREEQC for qualitative geochemical assessment. Each site had a groundwater model, integrated with a geochemical framework to inform risk evaluation and remedial design. Corrective action plans were developed using model predictions to assess remedies such as barrier walls, horizontal wells, collection trenches, phytoremediation, and monitored natural attenuation. All five sites showed varying degrees of groundwater impact from CCR units, with plume magnitude and extent reflecting site-specific hydrogeology, source water chemistry, and operational history. Key lessons include the importance of early geochemical conceptual site model development, the value of complementary modeling tools and the effectiveness of structured, multi-tool modeling in streamlining corrective action evaluation and selection.
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
Integrated Groundwater Flow and Transport Modeling for Coal Combustion Residual (CCR) Sites: From Closure Permitting to Corrective Action
Lexington, Kentucky
This session describes a coordinated multi-year effort to assess and manage groundwater quality at five CCR impoundments. The objectives were to (i) develop site-specific hydrogeologic and geochemical conceptual models; (ii) quantify groundwater flow and constituent transport under baseline and post-closure conditions; and (iii) design and evaluate corrective action strategies that achieve regulatory compliance and provide a defensible framework for long-term monitoring and management. The program highlights a phased approach aligned with regulatory requirements, progressing from closure construction to corrective action planning for detected exceedances. Comprehensive hydrogeologic datasets including borehole lithology, hydraulic testing, CCR source water characterization, and groundwater monitoring were assembled. Numerical and analytical modeling tools were applied: HELP for infiltration simulation, MODFLOW for three-dimensional flow, MT3DMS and MODPATH for advective-dispersive transport and plume migration, and PHREEQC for qualitative geochemical assessment. Each site had a groundwater model, integrated with a geochemical framework to inform risk evaluation and remedial design. Corrective action plans were developed using model predictions to assess remedies such as barrier walls, horizontal wells, collection trenches, phytoremediation, and monitored natural attenuation. All five sites showed varying degrees of groundwater impact from CCR units, with plume magnitude and extent reflecting site-specific hydrogeology, source water chemistry, and operational history. Key lessons include the importance of early geochemical conceptual site model development, the value of complementary modeling tools and the effectiveness of structured, multi-tool modeling in streamlining corrective action evaluation and selection.
