Using the Optical Image Profiler (OIP) and Hydraulic Profile Tool to Visualize Complex Petroleum LNAPL Migration

Presented on Tuesday, December 3, 2019
John Fontana, CPG, CWD, Vista GeoScience, Golden, CO

Many sites with petroleum based residual and mobile Non-Aqueous Phase Liquid (LNAPL) have puzzled investigators using conventional drilling and sampling investigation methods. Limited interval sampling from split-spoon cores, or even selected samples from a continuous core, create significant data gaps that limit our ability to see where LNAPL has migrated, how it got there, and where it is going within the subsurface. Subtle soil heterogeneity, and other site conditions, can create a much more complex migration pattern.

The Ultraviolet Optical Image Profiler (OIP-UV) is a direct-push optical sensing tool that was recently combined with the Hydraulic Profile Tool (HPT) and Electrical Conductivity (EC) tool, also called OiHPT-UV. The OiHPT-UV tool literally sees the LNAPL in the subsurface and identifies what the hydrostratigraphic pathways are that got it there. A 3D grid of OIP-UV, HPT, and MIP probe data was combined with monitor well data, LNAPL measurements, conventional soil samples, and input into three-dimensional (3D) modeling software to clarify and explain complicated LNAPL patterns observed at various sites.

In one example, the initial LNAPL release penetrated deep below the water table and found confined stratigraphic layers that allowed it to migrate counter to the groundwater gradient. The data also showed that an air sparge and vapor extraction system had effectively cleaned up LNAPL in the smear zone but was not able to reach the confined LNAPL. Another site with randomly occurring LNAPL in monitor wells was found to have LNAPL present mostly in a perched water bearing zone and also in a deeper confined zone. The deeper confined LNAPL may have migrated there via deep wells screens. 3D models of several examples are shown that demonstrate how the HRSC tools and 3D models can be used to explain these site complexities and thus aid in remedial design.

John Fontana, CPG, CWD
Vista Geoscience LLC, Golden, CO
John Fontana is a certified professional geologist and certified well driller with over 35 years of experience, and currently serves as CEO and owner of Vista GeoScience. His experience includes implementing high resolution site characterization, data modeling and interpretation, optimized in-situ remediation technologies, and gas migration investigations. John currently serves on two ITRC teams, Optimizing In-Situ Remediation Performance & Injection Strategies, and Implementing the Use of Advanced Site Characterization Tools and was nominated to the EPA’s Science Advisory Board on Hydraulic Fracturing. John earned a degree in Geology, Oceanography and Physics from Humboldt State University in California in 1981.

NGWA may only post those brown bag sessions, Webinars, event sessions, and like for which we have obtained copyright permission from the presenter. Furthermore, by accessing or downloading any of these items, you agree they are for your own personal use and may not be disseminated by any means to others via any medium. Click here to read NGWA's proprietary legend and disclaimers before proceeding.