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05 November 2007 AGE-NC Project No. 06-1481 Page 7 of 7 engage the expendable point and expose a column of strata from which soil gas can be extracted. A post run tubing adapter equipped with an O-ring to ensure a vacuum-tight seal is then attached to a '/4-inch diameter, single use, disposable polyethylene tubing. The sampling tube is then lowered through the center of the hollow drive rods and secured by threading into the expendable point holder. The probe rod is retracted a minimum of two feet, placing the expendable tip in soil and creating a void open boring. Above ground,the polyethylene tubing is attached to a vacuum sampling chamber.A Tedlar bag will placed into the vacuum chamber. The sampling tube will be attached directly to the Tedlar sampling bag,through a collapsible,air tight port. The vacuum chamber is then sealed. The vacuum will then be used to purge the exposed soil column, through the sampling tubing, until approximately three volumes of soil vapor or ambient air is evacuated through the sampling system. The vacuum is then applied to the chamber,creating a negative pressure on the inside of the sample Tedlar bag.The bag then fills with vapor from the subsurface, allowing the sample to enter directly into the Tedlar bag. On complete collection of the gas sample, the negative pressure in the chamber is reduced and the sampling bag sealed. Upon collection, each sample will be labeled, logged on a chain of custody form and place into a dry cooler.Samples will be delivered to a State-certified laboratory for analysis of constituents listed in Section 3.2. After collection of the sample, soil gas from the polyethylene tubing will be monitored for the presence of volatile organics using a PID pre-calibrated to isobutylene. 4.5. EQUIPMENT DECONTAMINATION Prior to use,all sampling tools used for sample collection will be thoroughly rinsed with clean water after being washed with a solution of Alconox. All probing rods will be cleaned prior to advancement at each probe boring location. 4.6. BORING ABANDONMENT The probe borings will be permanently sealed to prevent vertical migration of potential contaminants. Soil boring shall be abandoned by backfilling with portland cement from the total depth to surface grade. Advanced GeoEnvironmental,Inc.