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ITO E RO E K SOP No.026,REV.1 <br /> ASSOCIATES,INC INDOOR AIR AND SUB-SLAB SOIL GAS SAMPLING METHODS <br /> PAGE 14 <br /> the probe for the presence of high concentrations of the tracer gas. This is <br /> achieved by emplacing the tracer compound by wetting or spraying a paper towel <br /> or rag and wrapping around the area of the connection where leaks could <br /> potentially occur. <br /> 4. Include the tracer gas in the list of target analytes reported by the laboratory or <br /> use a portable monitoring device, such as a helium detector, to analyze a sample <br /> of soil vapor for the tracer prior to and after sampling for the contaminants of <br /> concern. The advantage of the second approach is that the real-time tracer gas <br /> sampling results can be used to confirm the integrity of the probe seals and allow <br /> for field adjustments to the sampling system train prior to formal sample <br /> collection.If leaks are identified,adjustments will be made to the sampling system <br /> train and the leak test will be conducted again to ensure adjustments were <br /> successful in correcting the identified seal issues. In the event a leak has been <br /> detected but cannot be resolved, the sample location should be decommissioned <br /> and a new one installed. <br /> 5. Collect samples as described in Section 2.4. <br /> 2.7 DECONTAMINATION <br /> In the event dedicated sampling equipment is not used at each sampling location, <br /> decontamination procedures should be incorporated into the sampling procedure between <br /> each sampling location. <br /> Sampling probes should be decontaminated before the first sample is collected and between <br /> sampling points. Probes that are grossly contaminated should be decontaminated using a <br /> high-pressure steam cleaner. Probes that are not grossly contaminated can be <br /> decontaminated by brushing off loose soil particles, then heating the probes until they are <br /> warm to the touch to drive off any volatile contaminants. Heating times of 7 to 10 minutes <br /> are generally sufficient for this purpose. This brushing and heating method greatly reduces <br /> the generation of decontamination fluids. <br /> Syringes must be decontaminated between each use. Purge and sample syringes must be <br /> disassembled and baked at 240°C for a minimum of 15 minutes or at 120°C for a minimum <br />