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ADVISORY - ACTIVE SOIL GAS INVESTIGATIONS <br />Evaluate site lithologic logs and adjust sample depth and location; <br />Collect new continuous soil core samples; <br />Use alternate low-flow sampling methods (see Appendix D); <br />Use passive soil gas methods (see Appendix A); and <br />Collect soil matrix VOC samples using USEPA Method 5035/8260 (DTSC, <br />2004). <br />If moisture or unknown material is observed in the sample container, cease soil gas <br />sampling until the cause of the problem is determined and corrected. Moisture detected <br />in either the sampling train or the sample container may indicate saturated conditions in <br />the subsurface. Vapor phase compounds may partition into the dissolved phase, <br />affecting the recovery of target analytes and causing analytical results to be biased low. <br />5.2.4 Drilling Refusal <br />If refusal occurs during drilling, soil gas samples should be collected as follows: <br />Install a replacement borehole at least five feet laterally from the original boring <br />location. If refusal still occurs after three tries, collect a soil gas sample at the <br />depth of refusal or use an alternate drilling method; and <br />If refusal occurs at depths less than five feet, collect the soil gas sample <br />following the precautions in Appendix D. Sealing off the probe to ambient air is <br />critical to obtaining high quality data. <br />5.3 SAMPLE CONTAINER HANDLING <br />Sample handling procedures cited in the analytical methods should be followed. <br />However, since most methods are not designed for soil gas, additional safeguards <br />should be implemented to maintain the integrity of the samples. If samples need to be <br />shipped to a stationary laboratory, then follow the container-specific handling <br />procedures below. <br />5.3.1 Syringes and Glass Bulbs <br />Samples in syringes and glass bulbs should be analyzed as soon as possible after <br />collection in a mobile laboratory and should never be transported. Samples in syringes <br />and glass bulbs should be kept in a cool dark location at all times, protected from <br />exposure to light, until the samples are analyzed. A cooler without ice works well for <br />syringe and glass bulb sample storage. <br />Do not subject syringe and glass bulb samples to extreme temperatures. Heat can <br />cause compound degradation and leakage from the syringe or glass bulb. Cold can <br />cause moisture condensation, which can affect the recovery of target analytes. If <br />condensation is observed, the sample should be discarded and a new sample should <br />be collected. <br />July 2015 28