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� Nftopl \� 9.2 Soil Vapor Sample Collection After each soil vapor probe assembly is complete, a minimum of 48 hours of stabilization time will be allowed before collecting each vapor sample. Once the vapor points have been allowed to stabilize, the above ground sample equipment will be assembled. A magnehelic gauge will be fitted to the three-way sample port assembly to measure the vacuum while purging is conducted. Three purge volumes, using a 60-millimeter (ml) syringe, will be removed from the vapor probe assembly. The purge volume will be calculated based on the internal volume of tubing and annular space around the probe tip and the tubing volume of the above ground assembly. Once purging is complete, a 400 ml Summa canister, fitted with a 200 ml/minute flow restrictor, will be connected to the vapor probe assembly and samples collected. Prior to sampling, a leak check compound derived from commercial computer"dust-off' spray (such as 1,1-Difluoroethane, or similar) will be applied to rags and used to assist with monitoring leaks within the above ground vapor probe assembly. The "dust-off' spray will be sprayed into a plastic bag containing several cotton cloth rags. The rags will be placed adjacent to, but not touching, each portion of the sample apparatus, including the area where the Teflon tubing exits the ground. V Upon completion of the project and to the satisfaction of the EHD, the vapor probe will be removed and the boring will be grouted with neat Portland cement from the boring terminus to ground surface. x V 9.3 Laboratory Analytical Protocol —Soil Vapor ac° Utilizing H&P Mobile GeoChemistry's laboratory in Carlsbad, California (ELAP certified), 41,,vt-` each soil vapor sample will be analyzed for volatile organic compounds (VOCs) using EPA Method TO-15. In addition to the standard TO-15 analytical suite, MTBE, ETBE, DIPE, TAME, TBA, 1,2-DCA, EDB, and TPHg (carbon range C6 to C12) will be analyzed. s8' �.. Additionally, each soil vapor sample will be analyzed for the leak check compound, with a method detection limit of less than 10 pg/l. Each sample will be screened at the laboratory to evaluate for elevated concentrations. EPA Method 82606 may be employed for some 46— samples to prevent an elevated dilution factor, which would affect the detection limit of some of the compounds. For quality assurance/quality control purposes, a minimum of one duplicate sample will be collected immediately after the original sample from a selected vapor probe location. One trip blank provided by the analytical laboratory will be analyzed 6— for target compounds. Each soil vapor sample will be properly labeled and submitted under chain-of-custody procedures. 9.4 Laboratory Analytical Protocol—Soil Soil samples collected at the terminus of the each vapor point, approximately 4.5 to 5.0 feet -- bgs, will be analyzed for TPHg and TPHd by EPA Method 8015M; and BTEX, MTBE, ETBE, DIPE, TAME, TBA, 1,2-DCA, and EDB utilizing EPA Method 8260B. One soil sample will also be analyzed for physical properties by PTS Laboratories in Santa Fe, California using their Vapor Intrusion Package (Johnson-Ettinger). Physical soil property analyses and methodologies will include moisture content using API RP40/ASTM D2216; dry bulk and grain density using API RP40; total porosity using API RP40; air filled and water filled porosity using API RP40; effective porosity using ASTM D425M; total pore fluid Workplan to Conduct Subsurface Soil Vapor Intrusion Study \�/// ATC Project 54.26874.0001 v `' Page 7