Abstract: Rapid In-Situ Subsurface Characterization of a Petroleum- Contaminated Site Using Laser Induced Fluorescence and Cone Penetrometer Testing

Scott C. Boorse

In-situ sampling techniques used to characterize the stratigraphy and extent of subsurface contamination are becoming increasingly common in environmental site investigations. Laser Induced Fluorescence (LIF) combined with Cone Penetrometer Testing (CPT) is a new in-situ technology that provides real-time data on the extent of Aromatic Petroleum Hydrocarbons and stratigraphy in the subsurface. Integrated LIF/CPT data can rapidly provide contaminant and geologic information necessary to define plume boundaries and design efficient and effective remediation plans.

The Rapid Optical Screening Tool (ROST^TM, a trademark of the Loral Corporation) combines state-of-the-art LIF technology in conjunction with CPT equipment. The combined ROST^TM/CPT system provides a two centimeter resolution which quickly and accurately delineates the vertical and horizontal extent of petroleum contamination. The system distinguishes between specific fuel types by obtaining wavelength-time matrices, which are three-dimensional representations of the fluorescence data. By performing the test in-situ, the combined system eliminates cuttings disposal and the cost and time of extensive laboratory analysis associated with other subsurface screening techniques.

The ROST^TM/CPT system was used at a former refinery to investigate the extent of petroleum hydrocarbons in the subsurface. The ROST^TM/CPT tool was hydraulically advanced to an average depth of 30 feet below grade at 150 grid locations in two separate areas. The results provided a clear real-time characterization of the vertical and horizontal extent of three separate plumes and the potential contamination migration pathways. Due to the rapid, continuous subsurface characterization, on-site decision making enabled a 50% reduction in the planned scope of work and significantly reduced the investigation costs to the client.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas