ARCHIVED REPORTS_VAPOR INTRUSION SURVEY - SOIL GAS SAMPLING REPORT

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The decon water generated during the field activities was stored in DOT approved 55-gallon drums and subsequently transported to a licensed waste disposal facility. ' 2.3 Soil Gas Sampling Procedures Soil gas sampling was performed after a minimum of 30-minutes after placement of the ' bentonite seal of the temporary sampling point to allow for equilibration of soil vapors within the area surrounding the temporary point. Connections PSC collected the soil gas samples by applying a low vacuum to the sampling points via 1-Liter SUMMA Canisters. The sampling system consisted of a manifold in which the sampling tube, flow regulator, purge canister, and the sampling canister were connected. The manifold also contained vacuum gauges to measure the vacuum within the canisters. The purge canister was connected nearest the valve and the sampling canister was connected at the ' furthest downstream position on the manifold. Leak Check ' Upon making the connections, the connections on the canister side of the regulator were leak tested by opening and immediately closing the purge canister valve to apply a vacuum on the ' gauges. The manifold and connections were deemed adequately sealed when the vacuum gauge on the canisters maintain vacuum for a 10-minute period. ' Purging Prior to installing the first temporary soil gas sampling point (SG-1), an adjacent (approximately 10 feet away) test boring was installed within the former excavation to ' perform a purge-volume test. Upon completion of the test point installation and the 30- minute bentonite seal, soil vapor samples were collected in three separate disposable syringes after extracting 1, 3, and 7 purge volumes. Each syringe containing the 1, 3, or 7 purge ' volume sample was screened with a Photoionization detector (PID). The purge volume test with the highest PID reading was used as the appropriate purge volume for subsequent borings. The sampling train purge volume was calculated as follows: ' Purge Volume=Inner Tubing Volume+Exposed Borehole Volume x 16.387 cubic inch to mL conversion factor (nr L)+(nr2L)x 16.387 x#of Purge Volumes=Total mL Based on the results of the purge volume test, soil vapor was purged to evacuate the internal volume of the air and other gases that may have accumulated in the sampling equipment (-1-inch by 6-inch annulus space and tubing inside diameter by length). The purging flow ' rate was regulated by a laboratory calibrated in-line flow regulator at approximately 167 milliliters-per-minute (ml/min). The flow could be slower than the calibrated regulator due to shallow soil conditions, but could not flow faster than the calibrated regulator. The in-line ' vacuum gauge was used to record purge volumes and times. The valve to the purge canister and manifold was opened and the initial vacuum measurement ' and time was recorded. The vacuum gauge on the down-hole side of the regulator was Vapor Intrusion Survey Soil Gas Sampling Report ' prepared For:Sara Lee Bakery Group,Inc. Prepared By:PSC Industrial Outsourcing,LP Sam Lee—Lincoln Stmet\2009_03_31-Soil Gas Sampling Report.doc March 31,2009 8