Presented by John V. Fontana, CPG, CWD – Vista GeoScience

High-resolution site characterization (HRSC) tools, when used properly, greatly improve LNAPL site investigations. This presentation focuses on the Optical Image Profiler (OIP), along with tools like the Membrane Interface Probe (MIP), Hydraulic Profiling Tool (HPT), and Electrical Conductivity (EC) sensor. Together, these tools provide detailed insights into petroleum product behavior underground. At many sites, NAPL may occupy just 10% of the plume volume, yet it holds up to 90% of the total mass. Therefore, detecting and mapping the NAPL accurately is critical. OIP tools for LNAPL site characterization can identify the persistent source zones that require focused remediation.

Three versions of the OIP exist, each designed to detect specific types of NAPL. These include light fuels like gasoline, mid-weight condensates, and heavier substances such as creosote and crude oil. The OIP system uses fluorescence to detect these compounds, while the HPT and EC tools help map subsurface layers. These tools can identify migration paths, confining layers, and back-diffusion zones. However, users must beware of false positives caused by natural minerals. Careful data interpretation helps distinguish real signals from background interference.

John Fontana will share several case studies that show how OIP tools for LNAPL site characterization shaped project decisions. At one site, investigators found condensate mass above the water table. This finding led the team to switch from injection to air sparge/vapor extraction. At another site, deep LNAPL movement was discovered in confined zones, moving against the groundwater flow. A third case revealed perched and deep LNAPL layers that traditional methods missed. One example even showed how monitoring wells can give false thickness readings due to smear zones.

Finally, 2D and 3D models will show how OIP tools refine conceptual site models (CSMs). These models improve system design and help teams choose better remediation strategies. Attendees will leave with practical knowledge to tackle complex petroleum sites more effectively.

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