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I <br /> Mr. Jim Barton <br /> RWQCB <br /> March 29, 2013 <br /> Page 8 <br /> i) The SUMMA canister. configuration (string) used to collect <br /> samples will include a pressure gauge, flow controller, and <br /> complimentary screw-type connector. <br /> ii) Normally, duplicate samples are collected simultaneously using <br /> both arms not connected to the sample tubing. However, because <br /> the tracer,gas shroud will not allow space for this configuration, <br /> duplicate samples will be taken sequentially, using the single <br /> sampling arm. i <br /> The following steps describe the soil gas sampling procedure: <br /> Soil Gas Probe Set up and Leak.Testing(Shut-In Test) <br /> 1) Advance the boring to 2 feet above the shallowest desired sample depth, to ensure <br /> that soil gas samples will be collected through a minimum of 2 feet of undisturbed <br /> soil. <br /> 2) Decontaminate the purge pump and Sample T with ambient air by running the <br /> pump with all valves open for 1 minute or until photoionization detector (PID) <br /> readings of the pump exhaust are 0.0 parts per million(ppm). <br /> 3) Leak test the Sample T by closing the valves on arms 2, 3, and 4 with the pump <br /> running; continue building vacuum with the pump until the maximum is attained. <br /> Turn off the pump and observe whether vacuum is maintained at the maximum <br /> reading for 1 minute. This.is the first aboveground leak test. <br /> a) The scale of the vacuum gauge is read in inches of mercury (in Hg). <br /> b) The pump used is limited to a maximum of approximately 21.5 in Hg. <br /> I <br /> c) If vacuum decreases, find and correct the leak. <br /> 4) Attach a 1 litter SUMMA canister to the in-line vacuum gauge on the Sample T. <br /> The sample tubing is not yet connected. <br /> i <br /> 5) Close the two valves on the Sample T that are not in use, open the in-line valve to <br /> the SUMMA canister (NOT the valve on the canister itself) and continue building <br /> vacuum with the pump until the maximum is attained. Turn off the pump and <br /> observe whether vacuum is maintained at the maximum reading for 1 minute. <br /> This is the second aboveground leak test. <br /> a) If vacuum decreases, find and correct the leak. <br /> i) The connections in the SUMMA canister/sampling string often <br /> leak. <br /> ii) If further tightening does not fix the problem, replace the canister. <br /> UW <br />