ARCHIVED REPORTS_VAPOR INTRUSION SURVEY - SOIL GAS SAMPLING REPORT

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' monitored for adequate flow. The purging was deemed complete based on the vacuum drop of the purge canister compared to the required purge volume. The amount of the vapor removed was confirmed by the elapsed purging time at an assumed flow rate of ' approximately 167 ml/min. At the completion of purging, the valve to the purge canister was closed and the final vacuum measurement and time were recorded. ' Sampling After the appropriate purge volume was removed, the soil gas sample was collected. The valve on the sample canister was opened and the initial vacuum and start time was recorded. The canister remained opened to collect the soil gas sample until the canister vacuum remaining was no less than 5-inches of mercury. Once the remaining vacuum reached 5-inches of mercury, the sample canister was closed and the remaining vacuum and completion time were recorded. The canister was appropriately labeled, removed from the manifold, and stored for shipment to the laboratory. Field Duplicate A field duplicate sample (SG-1 DUP) was collected from location SG-1. The duplicate was ' collected immediately following the collection of the first canister. Analyses ' The sample canister serial numbers, sample IDS, initial and final vacuum pressures, and the final sample times were recorded on the chain-of-custody (COC). The samples were ' submitted to Air Toxics, Ltd., a California certified laboratory. The samples were analyzed for the following constituents: • TPH-g by EPA Method TO-3; • BTEX, the five fuel oxygenates (methyl tertiary butyl ether [MTBE], di-isopropyl ether [DIPE], ethyl tertiary butyl ether [ETBE], tertiary amyl methyl ether [TAME] and tertiary butyl alcohol [TBA]), the fuel additives (1,2-dibromoethane [1,2-DBA] and 1,2-dichloroethane [1,2-DCA]), and IPA by EPA Method TO-15; and ' • Oxygen, carbon dioxide (CO2), and methane by ASTM Method D1946. 2.4 Soil Gas Sampling Observations The observations of the soil gas sampling event have been recorded and are presented on the Soil Gas Sampling Observation Summary Table in Appendix D. A detailed discussion of the ' field activities are presented as follows. An appropriate volume of dead-air was purged prior to collecting the soil gas samples to be ' submitted for analytical testing for each sampling location. The appropriate purge volume to remove was determined at the initial soil gas sampling location identified as "SG-Test". SG-Test was performed within the source area of the former UST excavation. This was the area expected to yield the highest PID readings. Based on the PID readings, the highest ' Vapor Intrusion Survey Soil Gas Sampling Report ' Prepared For:Sara Lee Bakery Group,Inc. Prepared By:PSC Industrial Outsourcing,LP Sam lee—Lincoln Street\2009_03 31-Soil Gas Sampling Report.doc March 31,2009 9