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10 <br /> 4. INVESTIGATION METHODS <br /> ' 4.1 PERMITTING <br /> A well permit application was submitted and approved by the San Joaquin County <br /> ' Public Health Services,Environmental Health Division(PHS/EHD) A copy of the well permit <br /> is located in Appendix B Prior to installing groundwater monitoring wells NP-1 and MW-10, <br /> ARCADIS Geraghty & Miller notified Underground Services Aiert (USA) to confirm the <br /> presence or absence of underground utilrtnes near the boring locations In addntnon, each <br /> ' borehole was hand-augered to approximately four feet below ground surface (bgs) to clear the <br /> location for unmarked lines or utilities <br /> 4.2 DRILLING AND SAMPLING <br /> 4.2.1 Monitoring Well Drillina and Installation: Hollow-Stem Auger Method <br /> Drilling for well NP-1 proceeded from ground surface to a depth of approximately 90 <br /> feet below ground surface (bgs) using 8-inch, outside diameter, hollow-stem augers Soni <br /> 1 samples were initially collected at 5-foot intervals using a spht-spoon sampler until 50 feet bgs <br /> ' and then continuously until total boring depth was reached The soul sampler was driven into <br /> the soul ahead of the augers providing a relatively slough-free 18-mch soul sample contamed in 3 <br /> ' six mch brass or stainless steel tubes The bottom sample tube was retained for possible <br /> laboratory analysis by placing plastic end caps over the ends of the brass tubes, labeling it, and <br /> ' submitting the sample to the on-site mobile laboratory for possible analysis The sample in the <br /> middle and upper brass tubes was used to evaluate soil characteristics and to perform field <br /> ' observations for the presence of organic vapor levels (OVLs) OVLs were measured using a <br /> Flame Ionization Detector (FID) In order to measure the OVL, a portion of soil at each <br /> ' sampling interval, was placed into a plastic bag, which was sealed and allowed to volatilize for <br /> a minimum of five minutes The tip of the FID was then inserted into the bag and an OVL was <br /> ' measured and recorded on the boring log The boring log form was used to document drilling <br />