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Geo ydrologic Consultants, Inc. mounted StrataprobeTM direct push rig(or equivalent), equipped with 1-inch diameter push rod,will be used to drive a hole to a depth of 5 feet. The probe will then be extracted and a new 0.125-inch I.D. TeflonTM tubing with a micro-porous screen will be inserted into the borehole to the total depth and sand,_pack will be poured around the probe. The remaining annulus will be filled with bentonite granules to the ground surface and hydrated to seal off each probe. TheIFrobes will then be allowed to equilibrate for a minimum of 30 minutes prior to collecting the soil vapor sample. The vapor samples will be collected from each of the soil vapor probes via a new Teflon syringe for direct injection into the GC/MS for analysis. A purge test will be performed by extracting one purge volume, three purge volumes, and seven purge volumes and analyzing each vapor sample. The purge volume with the highest concentrations will be used for the remaining soil;Vapor probes, and if the results are all similar, three purge volumes will be selected for use at the Site. Following purging a syringe sample will be collected for each location, labeled, and delivered directly to the onsite mobile laboratory which is certified by the State of California for the test procedures to be performed. Soil probe equipment will be cleaned between each sample probe location and new TeflonTM tubing will be used for each probe location. A rag soaked with shaving cream containing a tracer compound, or equivalent, will be placed on the ground surface next to each soil vapor probe to ensure that there is no short circuiting through the probe hole to the surface. If the tracer compound is detected in any of the samples analyzed, the probe will be re-installed and re-sampled. Following collection of the soil vapor samples,the Teflon tubing will be removed from the borehole and the surface will be capped with concrete to match the existing grade. Soil vapor samples will be analyzed by the onsite state-certified mobile laboratory for Gasoline Range Organics and volatile organic compounds (VOCs) including but not limited to BTEX, MTBE, additional oxygenates, and naphthalene by EPA Method 8260B using a GC/MS. A duplicate soil vapor sample will also collected and analyzed and an ambient air blank will be collected and analyzed for quality control measures. The proposed soil vapor survey will be conducted in accordance with the Department of Toxic Sub ' Substances Control's Guidan ce or the Evaluation .r and Mitigation of Subsurface Vapor Intrusion to Indoor Air dated December 15, 2004 (Revised f February 7,2005) including the use of proper sampling protocols and minimum laboratory detection limits and procedures. [ The laboratory results from the vapor samples will be i`used to evaluate the potential health risk to occupants of the buildings onsite and the surrounding areas south and east of the Site. The risk assessment will be performed according to the updated and revised California Department of Toxic Substances Control (DTSC),Guidance for the Evaluation and Mitigation of Subsurface Vapor Intrusion to Indoor Air guidelines using the DTSC Soil Gas Risk Model using the appropriate soil type for the Site. The Soil Vapor Survey and Health Risk Assessment Report will present the results of the soil vapor survey and will include the input and output printouts of the model and will present the associated Best 171 Workplan for SVS-HRA Page 3