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0 Soil and Groundwater Sampling—Initial Excavation Seven confirmation soil samples were collected from the walls and floor of the excavation and four 4- tube composites from the stockpiled soil In addition two groundwater grab samples were collected from water that had accumulated in the bottom of the excavation The samples were submitted under chain of custody to Argon Laboratories(FLAP No 2359) for analysis The suite of analyses consisted of BTEX, TPHg, TPHd and oxygenate additives utilizing EPA methods 8020, 8015m and 8260, respectively Sampling locations are shown on Figure 3 Anal3qical Results— Initial Excavation Soil sample WCE-20-NC, collected from the suspect area of the excavation, contained moderate concentrations of TPHd, toluene, ethylbenzene, xylenes and MTBE No other confirmation soil samples contained detectable concentrations of petroleum hydrocarbons analytes other than low levels of MTBE Analytical results for soil samples are summarized in Table 1 Laboratory data sheets and chain of custody documentation are included in Attachment B Both groundwater samples contained relatively high concentrations of TPHd and MTBE with no detectable concentrations of TPHg or BTEX Analytical results are summarized in Table 2 Laboratory data sheets are included in Attachment B Composite samples from the soil stockpiles contained relatively high concentrations of TPHd and low levels of MTBE Additional Soil Excavation and Sam lin A brief workplan addendum dated June 23, 1999 was submitted to PHS/EHD recommending excavation of the remaining contanvnated soil PHS/EHD concurred with the recommendation and approved the workplan on June 25 On June 30, 1999, the excavation was extended to the north in the area of residual contamination (Figure 2) Excavation proceeded laterally and vertically in this area until hydrocarbon odor was lacking and FID readings were minimal Confirmation samples were then collected at the depths of 18 and 20 feet below grade Approximately 50 cubic yards of soil was stockpiled on and covered with visqueen pending disposal Field notes are included in Attachment A The excavated area and samphng locations are shown on Figure 3 Analmcal Results-Additional Excavation The two soil samples were analyzed by Argon Laboratories for TPHd, TPHg, BTEX and oxygenate additives by the methods previously described Other than low levels of MTBE, no petroleum hydrocarbon analytes were detected in the samples Analytical results are summarized in Table 1 Laboratory data sheets and chain of custody documentation are included in Attachment B • WooLsey/reports/sodxsum doe 4