HIGH DENSITY SITE CHARACTERIZATION UTILIZING LASER INDUCED FLUORESCENCE (LIF) COUPLED WITH HYDRAULIC PROFILING TOOL (HPT)

High Resolution Site Characterization (HRSC) methods were utilized as part of a remedial response to a petroleum hydrocarbon release in Northwest Missouri. The site consists of alternating layers of fine- and coarse-grained sediments. Previous sample collection efforts at the site had revealed the presence of petroleum hydrocarbons within the saturated soils below the top of the water bearing zone. During the installation of air sparging points, light non-aqueous phase liquid (LNAPL) was unexpectedly encountered. In response, an LIF/HPT combination tool was employed to gather relative concentration data and relative permeability data across the site. The results of the LIF/HPT study indicated the presence of LNAPL trapped within lower permeable layers within the saturated zones underneath the top of the water bearing zone. The collected HRSC data provided valuable information that helped explain the magnitude and areal extent of elevated dissolved petroleum hydrocarbons. The HPT data confirmed the challenges of applying air sparging at the site as a remedial measure.