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GEOMWMIX <br /> TPHg and BTEX were reported at low concentrations in the 41-foot grab groundwater sample <br /> collected from boring 133-5 However, due to the sampling method, it was likely that the <br /> detections were a result of cross-contamination from the affected soil or groundwater at <br /> shallower depths (15 to 20 feet bgs) and not representative of the quality of groundwater from <br /> about 40 feet bgs <br /> 2002 <br /> Based on the results of the assessment conducted in 2001, Geomatnx recommended additional <br /> assessment to further delineate the lateral extent of petroleum hydrocarbons in soil and <br /> groundwater at the site (Geomatnx, 2002a), which was approved by the PHS/EHD Six soil <br /> borings (B3-8 through 133-13, Figure 2) were advanced to about 40 feet bgs at the site in 2002 <br /> (Geomatnx, 2002b) TPHg and BTEX were not detected in the soil and grab groundwater <br /> tsamples collected from about 20 and 40 feet bgs in these borings <br /> t3.0 ADDITIONAL SITE ASSESMENT <br /> In a June 24, 2002, letter to the Port, the EHS/PHD indicated that the vertical extent of <br /> petroleum hydrocarbons in groundwater at the site had not been adequately delineated based <br /> on their review of the 2002 assessment results (Geomatnx, 2002b) In response, the Port <br /> submitted a work plan for additional assessment and remediation evaluation of petroleum <br /> hydrocarbons in groundwater (Geomatnx, 2002b), which was approved by the PHS/EHD in <br /> an October 22, 2002, letter to the Port <br />' The activities conducted during this additional site investigation included grab groundwater <br />' sampling, snstallating of monitoring wells, and sampling the new and existing monitoring <br /> wells for remediation evaluation These activities are described in the following sections <br />' Prior to field activities, Geomatnx obtained monitoring well and soil boring permits from the <br /> PHS/EHD Proposed locations for borings and wells were marked at the site, and <br />' Underground Services Alert, the Port's Maintenance Department, and the tenant were notified <br /> for underground utility clearance prior to field activities <br />' 3.1 SOIL BORING AND GRAB GROUNDWATER SAMPLING <br />' <br /> Soil boring and grab groundwater sampling services were provided by Precision Sampling, <br /> Inc , of Richmond, California On January 28, 2003, boring B3-14 was advanced adjacent to <br /> I TRO]EM6000A6437 00016437-08 dw 5 <br />