Laserfiche WebLink
SOP No.021,REV.1 <br /> TO E RO E K <br /> SOIL GAS SAMPLING METHODS <br /> „ AssoCI ns INC. <br /> PAGE 3 <br /> • Tygon®or equivalent tubing of appropriate size for connecting the sorbent tube and pump <br /> and union fittings. <br /> • Cooler with ice. <br /> • Leak check compound <br /> 2.0 PROCEDURES <br /> This section describes selection of soil gas sampling locations and general preparation of the <br /> sampling system to be used. This section also provides detailed procedures for collecting samples <br /> using Tedlar®bags, syringes, Summa canisters, and sorbent tubes. Finally, this section discusses <br /> additional considerations that affect soil gas sampling—including duplicate and equipment blank <br /> sample collection, decontamination, and sample transfer—and summarizes the advantages and <br /> disadvantages of each sampling method. <br /> 2.1 SAMPLING LOCATION SELECTIONS <br /> Sampling locations should be selected and prepared for sampling as described in a site-specific <br /> quality assurance project plan and field sampling plan. Soil gas samples may be collected from <br /> depths as shallow as 3 feet or as great as 50 feet below ground surface (bgs), depending on the <br /> objectives of the project, soil type encountered, and the type of drilling equipment used. The <br /> horizontal spacing of soil gas sampling points (grid size)may be only a few feet or more than 500 <br /> feet. Again, this is a function of project-specific objectives and site conditions. <br /> 2.2 SAMPLING SYSTEM PREPARATION <br /> Sample probe assemblies generally consist of three types: <br /> • A hand-driven (hand auger)probe, typically good for shallow, temporary applications. <br /> • A hydraulic-driven (direct-push) probe, good for shallow to moderately deep temporary <br /> and permanent applications. <br /> • A drill rig-driven (hollow-stem auger) probe, typically good for deep, permanent <br /> applications including nested, multi-depth probe constructions. <br /> The probes may be assembled in series to reach the desired sampling depth. The probes will be <br /> driven to or emplaced at the desired sample collection depth, and then fitted with the Tygon° or <br /> equivalent sampling tube. During probe emplacement, subsurface conditions are disturbed. To <br />