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A4OM o Purge three times the volume of the sampling train and the annular space around the sample tip (which includes the 1 foot of sand and 1 foot of dry granular bentonite). • After successfully completing the shut-in test and pumping three purge volumes, collect soil vapor sample. 5.1 SAMPLING 5.1.1 Summa Canister Vacuum Check Prior to sampling, a vacuum gauge is used to measure and record the initial Summa® canister or equivalent vacuum pressure. • Initial canister pressure should be between -26 inches of mercury ("Hg) and -30"Hg. • If the initial pressure is less than - 26"Hg, the canister should be rejected and returned to the laboratory. • Record a post- sampling vacuum measurement to ensure that a full one liter of soil vapor is collected. 5.1.2 Soil Gas Sampling Soil gas will be collected with a Summa® canister or equivalent that has been leak-tested and purged at a rate of 100 to 200 mL/min before soil gas sampling takes place and submitted to the laboratory for analysis of VOCs using method to-15 or 8260B. For transport to the laboratory, attach an identification tag that indicates the: canister serial number, sample number, location, and date. Ship the canisters under proper chain-of- custody protocol to the project contracted analytical laboratory. Soil gas will not be sampled if measurable precipitation (0.25 inches in 24-hour period) has occurred within 48 hours of sampling. 5.1.3 Real Time Instrumentation After soil gas collection: • Connect the sample probe line with a sample "T" fitting to a Photoionization Detector (PID) to measure total non-methane hydrocarbons and a multi-gas meter (e.g., Landreth GEM 500) to monitor oxygen, carbon dioxide, and methane. 6 DECONTAMINATION After the installation and sampling of a soil vapor probe, all equipment/supplies that are to be re-used shall be properly decontaminated in accordance with SOP 200 - Decontamination Procedure. The installation equipment will be decontaminated prior to use and between each soil vapor bore installation in accordance with SOP 200 — Decontamination Procedure