Innovative exploration methods and advanced on-site field analytical techniques identified the presence or absence of petroleum hydrocarbon constituents (PHCs) in the soil and groundwater at multiple sites, quickly and effectively. Where present, the vertical and horizontal extent of PHCs was identified. The field program was performed using a cone penetrometer unit, two geoprobe systems, and two mobile laboratories, and was completed in four weeks.

Piezometric Cone Penetrometer Tests with soil Electrical Conductivity (CPTU-EC) measurements were used to rapidly assess site hydrostratigraphy. Three CPTU-EC soundings were typically performed at each site. Soil and electrical conductivity measurements were used to identify aquifer and aquitard units in real time and evaluate whether free-phase products were present at each site. Small diameter piezometers were installed in each CPTU-EC exploration to identify the direction of groundwater flow and to allow for sampling of ground water. In addition, penetrometer soil and ground water sampling were performed when it was anticipated that the lighter weight geoprobes would not be able penetrate to desired depths. The penetrometer truck was able to complete exploration work at one and one-half sites per day, on average.

Using a phased approach, soil and ground water samples were analyzed for PHCs in the field, providing quality real-time data. During Phase I, all soil samples were analyzed for total petroleum hydrocarbons (TPH) by infrared (IR) spectroscopy, using a modification of USEPA Method 418.1. Data from these initial locations directed subsequent soil and ground water sampling, both horizontally and vertically. Approximately 30 percent of the samples underwent subsequent analysis (Phase II) using a gas chromatograph (GC) for the specific analyte determination of benzene, toluene, ethylbenzene, and xylenes (BTEX), and fuel fingerprint identification.

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