Chemical Company; Delaware
The Delaware City PVC Site is a National Priority List (NPL) Site situated in Delaware City, Delaware. A Remedial Investigation/Feasibility Study (RI/FS) was conducted by Roux on behalf of a major chemical company. The RI identified and defined a plume of volatile organic compound- (VOC) contaminated groundwater approximately 1.6 miles long by 0.5 miles wide. VOCs in the plume consisted of part-per-million concentrations of 1,2-dichloroethane (1,2-DCA), vinyl chloride monomer (VCM), and trichloroethylene (TCE). The nature of the chemicals of concern and the hydrogeology of the Site made pump and treat remediation likely to be successful. Upon completion of the RI/FS, a Record of Decision (ROD) was issued by the United States Environmental Protection Agency (USEPA). Roux developed a site remedial program using a pump and treat system, as required by the ROD.
Roux used the numerical groundwater flow program MODFLOW to determine the number, location, and pumping rates for the interceptor wells. The numerical model simulated unconfined conditions. The model took into account uncertainties in well efficiencies and aquifer parameters such as hydraulic conductivity, and allowed for design flexibility to accommodate these uncertainties and still ensure capture of the plume.
A total of 17 interceptor wells were employed in the remediation system. The system has completely restored the impacted portion of the aquifer to drinking water standards with no rebound in concentrations. Due to the attainment of remedial objectives, the USEPA has approved complete shutdown of the groundwater remedial system. In the last 5-year review report (September 2014), the USEPA concluded that overall the Site is now protective of human health and the environment.
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Delaware City, Delaware
Design and Operation of Groundwater Intercept and Treatment System
Remedial Investigation/Feasibility Study