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A4OM <br /> • Each soil gas probe will be allowed to equilibrate for at least 2 hours if installed with <br /> direct push, and up to 48 hours if using hollow stem and a hand auger, or installed if <br /> fine-grained materials. <br /> 5 SAMPLING ASSEMBLY AND TRAIN <br /> After installation, the sampling train is connected directly to the vapor monitoring well tubing <br /> for purging and sampling. <br /> Once the sampling train is connected: <br /> • Leak test the system using the following: <br /> o Shut-in Test <br /> ■ Once sampling train is assembled, leave the canister valve in the <br /> closed position and apply a vacuum using a hand pump to the <br /> sampling line. <br /> ■ Observe the vacuum gauge (attached to pump or line with "T" fitting) <br /> for at least one minute. <br /> ■ If vacuum loss is observed, adjust fittings until vacuum does not <br /> noticeably dissipate. <br /> o Tracer Test <br /> ■ Introduce the liquid tracer compound (isopropyl alcohol) by applying to <br /> clean, white towels or clean shop rags. <br /> ■ Place the towels around all connections in the sampling train to <br /> evaluate potential leaks of ambient air into the sampling train. <br /> ■ The tracer should not be sprayed or poured onto the fitting directly. <br /> ■ Towels with the liquid tracer should be placed on the ground adjacent <br /> to the probe to evaluate soil column and probe construction <br /> breakthrough, as needed. <br /> ■ Connections can be individually checked by placing the tracer cloth in <br /> a plastic bag and using the bag to enclose individual connections. <br /> ■ Seal integrity is confirmed by analyzing the soil gas samples for the <br /> tracer compound; the tracer should be included in the laboratory <br /> analyte list. <br /> ■ If the concentration of the leak compound is greater than or equal to <br /> 10 times the reporting limit for the target analyte(s), then corrective <br /> action is required. <br /> • Purge the system <br />