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Lori Duncan April 24,2003 <br /> San Joaquin County <br /> Environmental Health Division <br /> measurement of the rate at which a gas escapes from a fixed surface area and has units of <br /> mass per unit volume and surface area. Since neither mechanical nor wind erosional <br /> forces will occur within the flux chamber, volatilization is the only plausible mechanism <br /> for contaminant emission. The samples will be collected in a 6-liter cylindrical, stainless <br /> steel flux chamber aliquot, placed inside the building, and then transferred into the <br /> evacuated SUMMA® canister for transport to the analyzing laboratory (EPA, 1986). A <br /> background sample will be collected from an area removed the contamination using the <br /> identical sample collection methods. <br /> Soil gas emissions will enter the open bottom of the chamber. The flux chambers will be <br /> anchored to the test and control floors with duct tape providing a seal from the ambient <br /> atmosphere. Assuming equilibration to steady state conditions (approximately six hours), <br /> a 6-liter aliquot was collected into a SUMMA® canister, certified clean by the laboratory. <br /> The sample will be analyzed for benzene using EPA Method TO-3 <br /> The data collected from the ambient air and air inside the building using the <br /> methodologies described above will give an accurate measurement of benzene <br /> concentrations present in the building. The measured benzene concentrations will be <br /> evaluated to calculate benzene exposures for workers in the building, and an assessment <br /> of the actual risks from exposure to benzene. <br /> REPORT <br /> A report of the indoor and background air sampling will be prepared containing a <br /> description of the field sampling activities, sample collection and analysis methods, and <br /> the laboratory results of the analysis of the air samples. The laboratory results will be <br /> used to calculate the risks, if any,posed by the residual contamination associated with the <br /> fuel release. The air sampling investigation will be used to prepare recommendations for <br /> site closure, including an Appendix B checklist, or additional source removal, as <br /> appropriate. <br /> Prepared By: <br /> Michael J. Kloberdanz, REA,REHS <br /> California Registered Environmental Assessor#02157 <br /> California Registered Environmental Health Specialist#4783 <br /> 2 <br />