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SOP—SG-1 <br />SOIL GAS WELL SAMPLING <br />STANDARD OPERATING PROCEDURE <br />2.4 SAMPLE COLLECTION <br />VVESr <br />i immmW serY ceE & 1nhw1ogy <br />Following purging activities, the tubing will then be attached to an analytical laboratory -prepared <br />one -liter Summa canister or sorbent tube. The Summa canisters will be delivered by the <br />analytical laboratory with a vacuum of approximately 30 -inches of mercury and outfitted with <br />0.125 -liter per minute flow control valve. The tubing will be connected to the Summa canister or <br />sorbent tube using airtight fittings. The flow control valve on the Summa will be opened slowly <br />to draw the vapor sample from the target depth. For sorbent tube sampling, tubing will be <br />connected to as peristaltic pump with a flow rate between 50m1/min to 200 ml/min (dependant on <br />sorbent tube type; for typical flow rates see attached Method TO -17). Following sample <br />collection, the Summa canister atmosphere will be measured with a vacuum gauge and recorded <br />on field data forms. Flow rates and duration for sorbent tube sampling will be recorded on field <br />data forms. <br />The Summa canisters and/or sorbent tubes will then be labeled and transported to a California <br />Department of Public Health (CDPH) Environmental Laboratory Accreditation Program (ELAP) <br />certified laboratory pursuant to ASTM D 4840 chain -of -custody protocols. <br />If low -flow or no -flow conditions (e.g., fine-grained soil, clay, soil with vacuum readings that <br />exceed approximately 10 -inches of mercury or 136 inches of water) are encountered, and low - <br />flow sampling is not successful, soil matrix sampling using EPA Method 5035A and analysis <br />using United States Environmental Protection Agency (USEPA) 8260B will be conducted <br />(DTSC, 2011). <br />2.5 LABORATORY ANALYSIS <br />Once the sampling has been completed, the samples will be transported to the laboratory <br />following the chain -of -custody procedures outlined in ASTM D 4840 for chemical analysis using <br />USEPA Method TO -15 (summa canisters) or USEPA TO -17 (sorbent tubes). The laboratory <br />will be advised to conduct analysis of the whole gas samples within 30 -days of receipt. <br />5 <br />