- Chemical manufacturing site
- DNAPL
- Adjacent to tidally influenced stream
- Multiple remedial design approaches employed, including ISCO
Inadequate maintenance at this former pesticide/herbicide aerosol can packaging company led to the release of solvents and pesticides from aboveground storage tanks and underground piping. The site was characterized by widespread low level pesticide contamination; soil and groundwater impacted with chlorinated solvent contamination; dense nonaqueous phase liquid (DNAPL) in groundwater adjacent to a stream; and pesticide and solvent impacts to the tidally influenced stream sediments as well.
Challenge
The Site’s legacy of partial investigations and limited remediations had created critical data gaps that needed to be addressed. Another challenge was to design a remediation that cost effectively addressed all impacted media without exacerbating impacts to the adjacent stream.
Solution
GZA identified all data gaps and completed the delineation with the assistance of site-specific clean-up criteria that were accepted by the NJDEP. Both engineering and institutional controls were employed to address contaminants of concern. The remedial design consisted of soil capping and deed notices to address soil contamination; in-situ chemical oxidation (ISCO) to address dissolved contamination; over drilling in the DNAPL impacted zone to remove a significant mass; hydraulic control in the DNAPL areas during injection to mitigate potential mobilization of DNAPL; long term monitoring and natural attenuation following source reduction; evaluating regional impacts to the stream to provide a background concentration of pesticides; and limited dredging of the stream adjacent to the facility
Benefit
GZA’s multi-pronged remedial design approach effectively addressed multiple areas of concern within the client’s budgetary goals, while providing necessary protections to the adjacent stream.