Dewatering Optimization Strategies in Support of Closure by Removal (CBR) to accelerate Groundwater Cleanup at Coal Combustion Residual Sites (CCR) with Case Study

Dewatering Optimization Strategies in Support of Closure by Removal (CBR) to accelerate Groundwater Cleanup at Coal Combustion Residual Sites (CCR) with Case Study

Grand Rapids, Michigan

Dewatering Optimization Strategies in Support of Closure by Removal (CBR) to Accelerate Groundwater Cleanup at CCR Sites with Case Study Authors Mr. Sean Larkin - United States - Haley & Aldrich Inc. Dr. Jacob Chu - United States - Haley & Aldrich Inc. Abstract This presentation is focused on coal combustion residual (CCR) sites in corrective action that are performing closure-by-removal (CBR) in support of an overall groundwater remedy. CBR is often coupled with a variety of groundwater treatment options, including (but not limited to), monitored natural attenuation and/or contingent active or passive treatment of areas within the plume where a CCR constituent persists in groundwater at levels above a groundwater protection standard (GWPS). Based on site conditions, dewatering is often required to access and remove CCRs as part of the CBR process. In those situations, the site dewatering system can also be optimized to remove CCR constituents from impacted groundwater and shorten the timeframe to achieve GWPS, thereby streamlining contingent groundwater treatment programs. The concepts of porewater flushing and dynamic pumping in conjunction with site dewatering will be reviewed in this presentation and include foundational groundwater management principles that can be used to enhance CCR constituent removal from impacted groundwater during the closure implementation period. To further illustrate these techniques, an example case study will be presented which includes site settings and numerical groundwater modeling. To compare the performance of CCR constituent removal from impacted groundwater, this case study will consider various configurations of dewatering well networks operated during the CBR process and their effectiveness and contribution to achieving GWPSs. The modeling outcomes will be used to further codify engineering principles to be applied for optimization of dewatering systems and the secondary beneficial effects on groundwater remediation.