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Swe 10 February 2009 AGE-NC Project No. 95-0173 Page 6 of 8 Above ground,the surface around the soil vapor sampler will be sealed with a bentonite sealant to pr7edlar t ambient air intrusion. The end of the polyethylene tubing is attached by a two-way inlet port to bag placed inside an SKC Vac-U-Chamber(lung box)vacuum chamber.A vacuum pump attached to a purge port of the vacuum chamber is then used to purge the exposed soil column, through the sampling tubing and inlet port, until approximately three volumes of soil vapor or ambient air is evacuated through the sampling system. The vacuum chamber is then sealed and the vacuum pump is attached to a vacuum outlet port of the chamber. When vacuum is applied to the chamber,a negative pressure is created around the Tedlar bag,which inflates,allowing the soil vapor sample to enter directly into the bag via the inlet port. When the sample is collected, the negative pressure in the chamber is reduced and the sample bag is sealed, labeled, log on a chain-of-custody form, and place into a dry cooler(room temperature). Subsequently, all of the collected soil vapor samples will be delivered to a State-certified laboratory for analysis of the chemical constituents listed in Section 2.2. After collection of the sample, soil vapor from the polyethylene tubi will be monitored for the presence of volatile organics using a photo-ionization detector(PID)pre calibrated to isobutylene 3.2.2. Confirmation Soil Sample Collection Soil borings B-1 1_,_B-12 and B-43 will be advanced to depths of 40 feet bsg utilizing a truck- mounted,hollow-stem drill rig and 8-inch diameter hollow-stem augers. Soil cuttings and rinseate will be containerized in properly labeled Department of Transportation(D.O.T.)-approved 55-gallon drums and stored in an area on the site lacking public access.Disposal alternatives for rinseate and stockpiled soil will be selected based on results of a laboratory analysis. During drilling, soil samples will be collected at five-foot intervals (beginning at 5 feet bsg) for logging purposes; selected soil samples will be analyzed by a CDPH-certified laboratory for the constituents listed in Section 2.2. Laboratory reports for soil analysis, testing methods, laboratory quality assurance/quality control (QA/QC) reports, and sample chain of custody documentation will be presented in a report with findings and recommendations. r In significant hydrocarbon-impact is not encountered from soil borings B-11, B-12 and B-13, then each boring will be completely back filled with a cement grout mixture (portland type II) in accordance with Section 13.12 of the San Joaquin County Public Health Services Environmental Health Division Well Standards. The grout mixture will consist of a ratio of six gallons water for every 94-pound sack ofportland type II cement. The drill rig hollow stem augers will be utilized as a tremie pipe during deployment of grout mixture. Advanced GeoEnvironmental,Inc.