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Kennedy/Jenks Consultants 3.3 Investigation Approach Fifteen LIF borings will be drilled to a depth of approximately 50 feet below ground surface (bgs), approximately 5 feet below the groundwater table at the approximate locations shown on Figure 3. Collection of grab groundwater samples at time of drilling is not proposed. The investigation will be conducted as follows: 1. For the First and Second Transects, engage a subcontractor to sweep each boring location for underground utilities using non-invasive geophysical means, and follow by clearing a pothole at each boring to 7 feet depth using a vacuum truck ("air knife"). 2. For the First and Second Transects, begin UVOST-LIF direct push drilling near the transect centers. Borings will be conducted approximately every 80 to 100 feet to the east up to approximately 200 feet or until there is no evidence of diesel or diesel impacts appear to be trace (e.g. minimal, not indicative of a significant release). Next, borings will be conducted every 80 to 100 feet from the transect center to the west up to approximately 200 feet or until there is no evidence of diesel or diesel impacts appear to be trace. The results of the First and Second Transect may indicate that the boring locations for the Third and Fourth Transects should be revised from what is shown on Figure 3. 3. Conduct utility clearance and air knife to 7 feet bgs at each proposed boring location at: Two boring locations along the Third Transect located south to southwest (upgradient) of the First Transect borings that exhibited the greatest indication of diesel; and Two boring locations along the Fourth Transect located north or northeast (downgradient) of the Second Transect borings that exhibited the greatest indication of diesel. 4. Conduct two UVOST-LIF borings at the air-knifed locations along the Third Transect (the upgradient transect). 5. Conduct two UVOST-LIF borings at the air-knifed locations along the Fourth Transect (the downgradient transect). Kennedy/Jenks intends to engage a subcontractor to provide the following services: air-knifing, direct-push drilling and UVOST, handling of investigative derived waste (IDW), and UVOST-LIF data imaging/modeling deliverable. 3.4 Field Preparation Field preparation tasks include the following: Develop a site-specific Health and Safety Plan (HASP), which is included in Appendix B. High Resolution Site Characterization Work Plan, BNSF Mormon Yard, Stockton, California Page 7 Os-groupladminljobll 311365020.01_bnsf \ 09-reports \ hrsc-wkpin1text.doc