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Kennedy/Jenks Consultants Section 3: High Resolution Site Characterization Plan This section presents the proposed HRSC technology, the conceptual HRSC subsurface investigation plan, field preparation tasks, and field procedures. 3.1 Laser Induced Fluorescence Technology To rapidly and effectively evaluate the potential source(s) of diesel found in groundwater at the Site, an exploration plan using ultra violet screening tool (UVOST)-laser-induced fluorescence (LIF) is proposed. LIF is an in situ screening tool that provides real-time semi-quantitative identification of volatile organic compounds (VOCs) and petroleum hydrocarbon compounds (PHCs) in soil and groundwater without collecting samples for laboratory analysis. LIF provides substantially more data in a short period of time than traditional drilling and sampling. The UVOST-LIF probe detects petroleum constituents by utilizing ultraviolet light generated by a laser and transmitted to the subsurface through a fiber optic cable and sapphire window. A real-time fluorescence response is produced when the ultraviolet light from the laser stimulates the polycyclic aromatic hydrocarbons (PAH) contained in the petroleum hydrocarbons in the subsurface. The fluorescence signal is directly proportional to the concentration encountered and is recorded as four peaks in percent response; the percent response for each peak cannot be correlated to actual concentrations and is thereby semi-quantitative. The ability to evaluate the UVOST-LIF data in real-time allows for the investigation crew to modify subsequent boring locations if appropriate (e.g. to follow preferential pathways). The fluorescence signal peak data and data imaging/modeling is recorded by the UVOST-LIF computer and is provided as a deliverable from the UVOST-LIF drilling services company at the conclusion of the investigation3. The enhanced decision making capability of UVOST-LIF and post-investigation deliverables can be used to inform the Site conceptual model for longer-term decision making for the Site. 3.2 Conceptual LIF Exploration Plan Given Site background information presented in Section 2.0, a conceptual LIF exploration plan is proposed that includes 15 LIF borings along four transects as shown on Figure 3. The initial conceptual LIF transect lengths are less than 1000 linear feet. The greatest density of borings is along the First and Second Transects (11 borings total) which run along and through the potential source areas. Two borings are proposed along the Third Transect, which is upgradient of the potential source areas and located south of the BNSF property boundary. Two borings are proposed along the Fourth Transect, which is downgradient of the potential source areas. Results from the First and Second Transects will be used to inform the final placement of borings along the Third and Fourth Transects. Additionally, as discussed in Section 3.1, data from a given LIF boring location helps the investigation crew in determining actual placement of subsequent drilling locations, allowing for modification to the conceptual plan as-needed at time of drilling. 3 Example boring logs and 3-dimensional imagery can be seen at: http://www.vironex.com/Services/HighResolutionSiteCharacterization.aspx High Resolution Site Characterization Work Plan, BNSF Mormon Yard, Stockton, California ois-g roup\admin‘ob\13\1365020.01_bnsnos-reportstrsc-wkon\text.doc Page 6