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A4OM • Use the tubing in the sampling train configuration to hold the union at the correct height in the hole Oust below the top). • Use modeling clay to seal around the probe to set it in place. 7.3 VALVE OPENING Open Valve#1 located at the end of the sampling train. 7.4 VALVE USE 7.4.1 Purge of Valve#1 Open Valve#1. Attach a hand pump with 15 mL stroke volume and built-in vacuum gauge to the purge tubing connected to Valve#1. • Two or three strokes should purge out the system. • No vacuum build up should show on the gauge during purging if the sub-slab material is dry and porous. • If no vacuum is observed during purge, close Valve#1. 7.4.2 Tracer Gas Test All samples will be collected using a tracer compound (isopropyl alcohol). Tracer gas isopropyl alcohol will be used by soaking clean white towels or clean shop rags with isopropyl alcohol and placing towels around train connections to test the integrity of the probe seal and the above ground connections. • The tracer should not be sprayed or poured onto the fittings directly. • Towels soaked with tracer will be placed on the ground adjacent to the probe to evaluate soil column and probe construction breakthrough, as needed. • Connections can be individually checked by placing the tracer cloth near the individual connections without touching the connections for one full minute. • Seal integrity is confirmed by analyzing the soil gas samples for the tracer compound; the tracer should be included in the laboratory analyte list. • The tracer gas check will be performed within the first 30 minutes of sample collection. • If the concentration of the leak compound is greater than or equal to 10 times the reporting limit for the target analyte(s),then corrective action is required. 7.5 SAMPLING • Open Summa® canister or equivalent valve completely and record the time. • After approximately 5 to 10 minutes with regulator set at 100 to 200 mL/min with a 1 L Summa® canister or equivalent, or if the vacuum gauge reading drops below-5 inches of Hg before 10 minutes,close the canister valve completely. • Record the time and vacuum gauge reading. • Close valve completely. • Remove the pressure gauge. 7.6 CANISTER BRASS CAP REPLACEMENT • Replace brass cap on the canister. 8 QUALITY CONTROL Quality control procedures have been developed to verify equipment integrity,sample quality, and sample repeatability. Care should be taken to keep all sampling equipment, especially the canisters, safe from damage. 8.1 FIELD DUPLICATES Afield duplicate will be collected for 10%of the samples collected. Field duplicates are collected by attaching a T-fitting to the end of the tubing prior to the flow controller. A canister with a flow controller is attached to each end of the T-fitting. For sampling, both canister valves are opened and closed simultaneously. Use the procedure described above to collect samples. 9 DECONTAMINATION Designated stainless steel Swagelok®connectors or equivalent will be thoroughly decontaminated using a Liquinox®wash followed by a distilled water rinse. Non-designated stainless-steel assemblies will be thoroughly decontaminated. • Purge with at least half a liter of air(e.g.,with hand pump or peristaltic pump).