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01 May 2000 r <br /> AGE-NC Project No 96-0232 <br /> Page 4 of 11 <br /> 32 SOIL-GAS AIR SAMPLE COLLECTION <br /> _ x , <br /> Soil-gas air samples were collected utilizing a Geoprobe soil-gas air sampling assembly, the <br /> assembly consisted of an expendable vapor point attached to the bottom of 1-inch diameter hollow, <br /> drive rods The assembly was advanced to the target depth (5 feet bsg) and was retracted upward <br />' approximately six inches to expose the desired strata, soil-gas air samples were extracted by r <br /> lowering a 'sampling tube through the center of the hollow drive cods to the desired depth and <br /> threading into the expendable point holder <br /> At the surface, the polyethylene tubing was attached to a vacuum pump The vacuum'pr mp applied <br /> _a negative pressure to the exposed soil column until an estimated three tubing-volume's of soil gas - <br /> I and/or ambient air was evacuated through the sampling system Aftei purging the system, a Tedlar <br /> bag was placed into a vacuum chamber and attached directly to the sampling tube tluough-a <br /> collapsible, air tight port A negate e pressure was applied to the vacuum chamber with the vacuum <br /> Ipump, expanding the Tedlar bag, allowing the sample to enter directly into the Tedlar bag <br /> Following sample collection, the samples were placed rn a covered container and transported under <br /> chain-of-custody to Precision Enviro=Tech Analytical Laboratory (PEAL), a DHS-certified <br /> laboratory in Stockton, California Each sample was,analyzed within 72 hours of collection for TPH- <br /> g, BTEX and MTBE in accordance with EPA Method TO-14 <br /> ' s <br /> 3 3 EQUIPMENT DECONTAMINATION <br /> Prior to sample collection, Geoprobe soil sampling equipment was thoroughly rinsed with clean <br /> water after washing with a solution of-Alconox Geoprobe rods were thoroughly cleaned prior to soil <br /> probe boring advancement <br /> t <br /> 34 ANALYTICAL RESULTS OF SOIL-GAS AIR SAMPLES <br /> A total of seven soil-gas air samples were submitted for laboratory analysts TPH-a, benzene and ' <br /> MTBE were detected in the soil-gas air sample collected fronn P-6 at concentrations of 600 ,ug/l, 0 5 <br /> ,ug/l and'2 5 4g11, respectively none of the analytes were detected to any other soil-gas an samples <br /> Analytical results of soil gas samples are summarized in Table 1 The laboratory report (Precision <br /> Enviro-Tech Analytical Laboratory Sample I D 's,AG31500-01 through'07) and,chann-of-custody <br /> forms are presented in Appendix E <br /> , r r <br /> Adsanccd GcoEnr ironwcntal Inc <br /> " <br />