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ppm and 46 pent, respectively. Additionally, both samples detected <br /> concentrations of several aromatic compounds (BSE X).. orgaiclea indicated <br /> and EDB were non-detectable in both sample. <br /> that several of the aromatic constituents exceeded the maximum <br /> allowable levels that may be safely left in the ground without <br /> threatening groundwater quality (based on the 1989 Luft Manual <br /> leaching potential .risk analysis) . Consequently, in order to help <br /> define the vertical extent of vadose zone contamination and <br /> facilitate site closure, SJCLHD requested that an exploratory angle <br /> boring (designated B2) be drilled near the southern end of the tank <br /> pit <br /> and extend beneath the southwestern corner of the sites <br /> market/cafe. <br /> 3.2 Exploratory So-1 Borings <br /> 3.2.1 Predrilling Activities <br /> Prior to drilling, TPE obtained soil boring permits from the County <br /> of San Joaquin Department of Public Health services, Environmental <br /> Health Division (see Appendix A) . In addition, Underground Service <br /> Alert (U-A Digs) was notified so that any underground utilities in <br /> the vicinity of the borings could be located and marked. <br /> 3.2.2 soil Boring and Sampling Procedures <br /> i <br /> Both soil boring B1 and B2 were drilled by icon Exploration, a <br /> State of California licensed water well driller (C-57 license <br /> X563305) . Boring Bi was advanced using 8-inch O.D. , hollow-stem, <br /> auger drilling equipment to a depth of 50 feet. Boring B2 (see <br /> Figure 3) was drilled at an angle of 15 degrees east of vertical <br /> with 6-inch O.D. hollow-stem augers using a track-mounted drilling <br /> rig. The augers from both rigs were steam-cleaned before drilling <br /> to prevent the introduction of off-site contamination. <br /> Representative soil samples were collected for stratigraphic and <br /> chemical characterization at approximately 5-foot depth intervals, <br /> or at changes in lithology. The samples were obtained by advancing <br /> a 2.5 inch O.D. California split--spoon sampler, equipped with 2- <br /> inch diameter by 6-inch long brass tubes, into the undisturbed soil <br /> beyond the tip of the augers. Samples collected for chemical <br /> open <br /> analysis were preserved in the tubes by quickly covering p- <br /> al <br /> 6 <br />