EHS Support was retained by the client to review historical environmental investigations to identify data needs for the assessment and development of a cleanup remedy to address light non-aqueous phase liquid (LNAPL) contamination at a former paint manufacturing site. Investigation and remedy assessment activities were conducted pursuant to state and federal Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) requirements. The purpose of the assessment was to refine the understanding of the extent, mobility, and recoverability of the LNAPL within the site so that a final site cleanup remedy could be selected and proposed to the regulatory agencies.
The client is a paint, varnish, and lacquer manufacturer that operated a former plant since the mid-1800s. The site was listed on the federal National Priorities List (NPL), where environmental investigation and cleanup activities had been performed since the late 1970s. The primary source areas for LNAPL impact in soil, soil vapor, and groundwater at the site were identified around former tank farms and operational areas.
EHS Support developed a plan to leverage historical site investigation data and collected supplemental investigation data to characterize the nature of LNAPL mobility, recoverability, and its impact on the site. The remedial investigation activities and feasibility studies were conducted on an accelerated 12-month time frame to meet an aggressive administrative schedule.
We performed oil and groundwater investigations to collect geology, hydrogeology, and petrophysical testing data to specify the spatial extent, mass, and volume of LNAPL present in the subsurface. In addition to defining the nature and extent of LNAPL impacts, we also completed natural source zone depletion (NSZD) studies at the site in combination with focused biological studies to determine the role of natural processes and/or enhanced bioremediation in the ultimate restoration of groundwater quality.
Based on these supplemental evaluations, a feasibility study was submitted and approved by the United States Environmental Protection Agency (USEPA) with NSZD and enhanced bioremediation selected as the remedy for LNAPL affected soil and groundwater. Major negotiations with stakeholders and USEPA were conducted to support the preferred remedy and address requests for consideration of more aggressive and costly remedial approaches (for example thermal remediation).