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GeosptecO consultants The lid of the lung box will be opened, the valve on the Tedlar bag closed, and the Tedlar bag removed from the lung box. The Tedlar bag will be connected to the helium meter,photoionization (PID), and landfill gas meter (oxygen, carbon dioxide and methane) in sequence, by opening the Tedlar bag valve, and recording the stabilized readings. If the concentration of helium in the Tedlar bag is greater than 5% of the concentration in the shroud, the probe seal and fittings should be checked to determine the location of the leak. Once the leak has been fixed, resume purging and field screening. The purging and field screening procedure will be repeated for a minimum of three sets of readings. 5 SUMMA CANISTER LEAK TEST Valves V-1 and V-2 will be closed and then valve V-3 (summa canister valve) will be opened to induce a vacuum on the sample train. Valve V-3 will then be closed to leave a vacuum of about 30 in Hg in the sample train. The vacuum in the sample train will be observed for a short duration(30 seconds) to ensure it does not dissipate as a final check that the sample train does not contain any leaks. 6 SUMMA CANISTER SAMPLING After the summa canister leak test,valve V-1 will then be opened. Then valve V-3 (summa canister valve) will be opened to begin the sample collection. The sample collection start time should be recorded. The vacuum gauge on the Summa canister should be monitored and valve V-3 should be closed when the residual vacuum in the canister is about 5 in-Hg. The sample collection finish time should be recorded. Following sample collection, connect a vacuum gauge directly above valve V-3, open valve V-3 and record the final vacuum of the summa canister. Close valve V-3 after the vacuum reading is recorded. The final vacuum reading will be included on the chain of custody so that the receiving laboratory can confirm if the summa canister has leaked during transit. 7 BLANK SAMPLES (OPTIONAL) Blank samples will be collected based on the project specific data quality objectives. An equipment blank is collected by connecting a Summa canister to a fully assembled soil gas probe(screen,tubing,and valve)prior to installation,via Swagelok fittings through a 200 milliliter per minute(mL/min) flow controller. The Summa canister valve is opened to draw the contents of the tubing and outdoor air into the canister through the probe tip and Swagelok valve. Trip blanks are required by some jurisdictions and consist of a unused Summa canister being sent by the laboratory to travel with the primary laboratory samples and then being returned to the laboratory unused. The laboratory will then proceed to analyzed the contents of the Summa canister. 2 October 2020