PEM staff provided geologic consulting and management of a soil and groundwater sampling effort at a Formerly Used Defense Site (FUDS) for the U.S. Army Corps of Engineers (USACE) during the fall and winter of 2016. The 15-acre site was a former fuel distribution facility that once contained five above ground storage tanks (AST), pump houses, and subsurface fuel pipe line. The facility was in use from the late 1950’s until 1990. The combined capacity of the five ASTs was approximately 3.5 million gallons. Soil and groundwater at the site is impacted with light non-aqueous phase liquid (LNAPL) of jet-propulsion 4 (JP-4) aviation fuel. The site is under jurisdiction of the Massachusetts Department of Environmental Protection (MassDEP) in accordance with Massachusetts Contingency Plan (MCP) requirements.
The objective of the SSI was to determine the nature and extent of contamination in soil and groundwater at the site and delineate and assess LNAPL mobility. Collected data is being used to prepare a Phase II Site Assessment Report and Risk Assessment. To achieve this objective, the field investigation included Laser Induced Fluorescence (LIF) optical, Hydraulic Profiling Tool (HPT), and Membrane Interface Probe (MIP) screening technologies to determine the vertical and horizontal soil contamination profile. All three screening tools are deployed using a direct push technology (DPT) drill rig. The LIF is a fiber optic-based fluorescent system that can detect petroleum through induced flurorescence. The HPT tool determines soil permeability and potential LNPAL mobility. The MIP tool was used to determine the lateral and vertical extent of dissolved phase volatile organic compounds (VOCs) in groundwater along the site boundary and where existing monitoring well coverage was not available.
Forty four LIF and 28 MIP/HPT locations were investigated from November 2016 to January 2017. LIF borings were advanced to depths of 26 to 60 feet below ground surface (bgs). Real-time LIF data identified areas at the site where LNAPL was present as well as depth to groundwater. MIP borings were advanced to depths of 50 to 80 feet below ground surface (bgs). The real-time MIP data indentified dissolved-phase VOCs in groundwater and indicated that site contaminants were at deeper depths than originally thought. The LIF and MIP/HPT data was used during the SSI field effort to identify the locations of new groundwater monitoring wells that were installed. In addition, the data was also modeled to provide a 2-dimensional and 3-dimensional graphical images of the site contamination.