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containment unit during soil probe purging and sampling. At least three tubing <br /> volumes of air were purged into the purge canister prior to sampling. Immediately after <br /> purging, soil vapor samples were collected at a sampling rate of 100- 200 milliliters per <br /> minute using the second 1-liter summa canister. The vapor samples were labeled and <br /> stored in a non-cooled ice chest until delivery to the analytical laboratory. <br /> 2.2 FINDINGS <br /> The soil vapor samples collected from the 5 and 16 fbg vapor probes were analyzed for <br /> benzene, toluene, ethylbenzene, xylenes (BTEX), and naphthalene. In addition, the <br /> duplicated sample and the trip blank were analyzed for these compounds. None of <br /> these compounds were detected in any of the samples collected. <br /> The leak detection compound, helium, was detected in the 16 fbg sample. The <br /> concentration was 28,200 micrograms per cubic meter or 0.0173%. The starting helium <br /> concentration within the containment unit was 50%. Therefore, the detection is 0.03° of <br /> the starting concentration which is not indicative of an unacceptable leak. The analytical <br /> results are summarized on Table 1. <br /> 3.0 CONCLUSIONS <br /> Soil vapor samples collected during July 2010 indicate that BTEX and naphthalene are <br /> not present in soil vapor in the vicinity of the proposed high school. As requested in the <br /> RWQCB August 11, 2010 letter,we will request no further action for this site if the third <br /> quarter groundwater monitoring results are consistent with previous quarters results. <br /> os�u2li�) 2 CONESTOGA-ROVERS&ASSOCIATES <br />