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Horizontal Wells for CCR Applications – Results and Lessons Learned
Description
Since 2016, Ellingson-DTD has advanced the use of horizontal directional drilling (HDD) for installing wells in, under, and adjacent to coal combustion residual (CCR) basins, evaporation ponds, and flue gas desulfurization (FGD) ponds at coal-fired power plants across the United States. Although horizontal wells have supported environmental remediation since the late 1980s, their first application within ash basins occurred in 2016. Since then, more than forty-one directional wells have been installed across ten states to facilitate groundwater containment and pore water removal. HDD enables “bottom-up” dewatering by positioning wells near the base of ash basins, a capability made possible through advancements in drilling and guidance technologies. These innovations allow installations beneath unstable ash, liners, and free water without requiring personnel to work directly on the ash surface. Horizontal CCR wells have become critical for managing pore water in both closure-in-place and closure-by-removal strategies, as well as for controlling groundwater interaction with ash. Of the wells installed, eighteen serve groundwater control functions—via injection or extraction—beneath basins or near site perimeters, while twenty-three are dedicated to pore water extraction. This presentation examines the performance of these wells, which have been deployed in basins containing bottom ash, fly ash, and mixed CCR materials, including gypsum and FGD byproducts. Post-installation pumping rates range from approximately 5 to over 60 gallons per minute (gpm). We will discuss directional well installation methods, share lessons learned from field applications, and evaluate operational outcomes to date.
Horizontal Wells for CCR Applications – Results and Lessons Learned
Lexington, Kentucky
Since 2016, Ellingson-DTD has advanced the use of horizontal directional drilling (HDD) for installing wells in, under, and adjacent to coal combustion residual (CCR) basins, evaporation ponds, and flue gas desulfurization (FGD) ponds at coal-fired power plants across the United States. Although horizontal wells have supported environmental remediation since the late 1980s, their first application within ash basins occurred in 2016. Since then, more than forty-one directional wells have been installed across ten states to facilitate groundwater containment and pore water removal. HDD enables “bottom-up” dewatering by positioning wells near the base of ash basins, a capability made possible through advancements in drilling and guidance technologies. These innovations allow installations beneath unstable ash, liners, and free water without requiring personnel to work directly on the ash surface. Horizontal CCR wells have become critical for managing pore water in both closure-in-place and closure-by-removal strategies, as well as for controlling groundwater interaction with ash. Of the wells installed, eighteen serve groundwater control functions—via injection or extraction—beneath basins or near site perimeters, while twenty-three are dedicated to pore water extraction. This presentation examines the performance of these wells, which have been deployed in basins containing bottom ash, fly ash, and mixed CCR materials, including gypsum and FGD byproducts. Post-installation pumping rates range from approximately 5 to over 60 gallons per minute (gpm). We will discuss directional well installation methods, share lessons learned from field applications, and evaluate operational outcomes to date.
