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2.4.4 The leak test should include an analysis of the leak check compound. <br /> If a leak check compound is detected in the sample, the following <br /> actions should be followed: <br /> A The cause of the leak should be evaluated, determined and <br /> corrected through confirmation sampling; <br /> B. If the leak check compound is suspected or detected as a site- <br /> specific contaminant, a new leak check compound should be <br /> used; <br /> C. If leakage is confirmed and the problem can not be corrected,the <br /> soil gas probe should be properly decommissioned; <br /> D. A replacement probe should be installed at least five(5)feet from <br /> the original probe decommissioned due to confirmed leakage, or <br /> consult with Agency staff; and <br /> E. The leak check compound concentration detected in the soil gas <br /> sample should be included and discussed in the report. <br /> 2.5 Purge/Sample Flow Rate <br /> Sampling and purging flow rates should not enhance compound partitioning <br /> during soil gas sampling. Samples should not be collected if field conditions <br /> as specified in Section 2.6.4 exist. <br /> 2.5.1 The purging or sampling flow rate should be attainable in the Iithology <br /> adjacent to the soil gas probe. <br /> A To evaluate lithologic conditions adjacent to the soil gas probe <br /> (e.g., where no-flow or low-flow conditions), a vacuum gauge or <br /> similar device should be used between the soil gas sample tubing <br /> and the soil gas extraction devices (e.g., vacuum pump, Summar"" <br /> canister). <br /> B. Gas tight syringes may also be used to qualitatively determine if a <br /> high vacuum soil condition (e.g., suction is felt while the plunger is <br /> being withdrawn) is present. <br /> 2.5.2 The Agency recommends purging or sampling at rates between 100 <br /> to 200 milliliters per minute (ml/min)to limit stripping, prevent ambient <br /> air from diluting the soil gas samples, and to reduce the variability of <br /> purging rates. The low flow purge rate increases the likelihood that <br /> representative samples may be collected. The purge/sample rate <br /> may be modified based on conditions encountered in individual soil <br /> gas probes. These modified rates should be documented in the soil <br /> gas report. <br /> 01/28/2003 - 11 - <br />