Weston Solutions, Inc
The Influence of an Integrated Remedial System on Groundwater Hydrology
Jan. 1, 2000- By: William H. Schneider
Courtesy ofWeston Solutions, Inc
ABSTRACT
This paper summarizes the development of a remedial system designed to hydraulically contain and ultimately reduce a plume consisting of primarily 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA). The system consists of groundwater circulating wells or extraction wells located in the core of the 1,1,2,2-TeCA plume to provide active source control, combined with monitored natural attenuation (MNA) and phytoremediation instituted to further reduce dissolved-phase contaminants. Monitoring of natural attenuation parameters indicates that abiotic and biotic degradation is significantly reducing 1,1,2,2-TeCA concentrations. Phytoremediation is provided by a 4.5-year-old plantation of 172 hybrid poplars observed to be seasonally influencing groundwater hydrology. A 3D-geospatial model (earthVision®), which was constructed based on extensive geological, geophysical, and chemical data, defines both the hydrostratigraphic framework and the 1,1,2,2-TeCA distribution and is the basis for a 3D-groundwater flow (MODFLOW) and contaminant transport (RT3D) model. Model results indicate that the system may remove 85% of the total 1,1,2,2-TeCA mass after 30 years, with groundwater wells and MNA providing the bulk of mass removal. Phytoremediation emerges as a significant contributor by providing 7% of the total mass removal. Field evidence and modeling indicate that the integrated remedial system is capable of effectively reducing contaminant mass, thereby satisfying the remedial objective.
This paper summarizes the development of a remedial system designed to hydraulically contain and ultimately reduce a plume consisting of primarily 1,1,2,2-tetrachloroethane (1,1,2,2-TeCA). The system consists of groundwater circulating wells or extraction wells located in the core of the 1,1,2,2-TeCA plume to provide active source control, combined with monitored natural attenuation (MNA) and phytoremediation instituted to further reduce dissolved-phase contaminants. Monitoring of natural attenuation parameters indicates that abiotic and biotic degradation is significantly reducing 1,1,2,2-TeCA concentrations. Phytoremediation is provided by a 4.5-year-old plantation of 172 hybrid poplars observed to be seasonally influencing groundwater hydrology. A 3D-geospatial model (earthVision®), which was constructed based on extensive geological, geophysical, and chemical data, defines both the hydrostratigraphic framework and the 1,1,2,2-TeCA distribution and is the basis for a 3D-groundwater flow (MODFLOW) and contaminant transport (RT3D) model. Model results indicate that the system may remove 85% of the total 1,1,2,2-TeCA mass after 30 years, with groundwater wells and MNA providing the bulk of mass removal. Phytoremediation emerges as a significant contributor by providing 7% of the total mass removal. Field evidence and modeling indicate that the integrated remedial system is capable of effectively reducing contaminant mass, thereby satisfying the remedial objective.
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