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27 February 2007 <br /> AGF-NC Project No. 07-1514 <br /> Page 6 of 6 <br /> Above ground,the polyethylene tubing is attached to a vacuum sampling chamber.A Tedlar bag will <br /> placed into the vacuum chamber. The sampling tube will be attached directly to the Tedlar sampling <br /> bag,through a collapsible, air tight port. The vacuum chamber is then sealed. The vacuum will then <br /> be used to purge the exposed soil column, through the sampling tubing, until approximately three <br /> volumes of soil vapor or ambient air is evacuated through the sampling system. The vacuum is then <br /> applied to the chamber,creating a negative pressure on the inside of the sample Tedlar bag. The bag <br /> then tills with vapor from the subsurface, allowing the sample to enter directly into the "Medlar bag. <br /> On completion of the collection of-the gas sample, the negative pressure in the chamber is reduced <br /> and the sampling bag sealed. Upon collection, each sample will be labeled, logged on a chain of <br /> custody form and place into a dry cooler. Samples will be delivered to a State-certified laboratory <br /> for analysis of the constituents described in Section 3.2. <br /> After collection of the sample, soil gas from the polyethylene tubing will be monitored for the <br /> presence of volatile organics using a photo-ionization detector pre-calibrated to isobutylene. <br /> 4.3. EQUIPMENT DECONTAMINATION <br /> Prior to use,all sampling tools used for sample collection will be thoroughly rinsed with clean water <br /> after being washed with a solution of' Alconox. All probing rods will be cleaned prior to <br /> advancement at each soil boring location. <br /> 4.4. BORING ABANDONMENT <br /> All soil borings will be permanently sealed to prevent vertical migration of potential contaminants. <br /> Soil borings shall be abandoned by backfilling with portland cement from the total depth to surface <br /> grade. <br /> Advanced CeoEnvironnâ–șeatal,Inc. <br />