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05 November 2007 <br />AGE-NC Project No. 06-1481 <br />Page 7 of 7 <br />engage the expendable point and expose a column of strata from which soil gas can be extracted. A <br />post run tubing adapter equipped with an 0-ring to ensure a vacuum-tight seal is then attached to a <br />1/4-inch diameter, single use, disposable polyethylene tubing. The sampling tube is then lowered <br />through the center of the hollow drive rods and secured by threading into the expendable point <br />holder. The probe rod is retracted a minimum of two feet, placing the expendable tip in soil and <br />creating a void open boring. <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 fills with vapor from the subsurface, allowing the sample to enter directly into the Tedlar bag. <br />On complete collection of the gas sample, the negative pressure in the chamber is reduced and the <br />sampling bag sealed. Upon collection, each sample will be labeled, logged on a chain of custody <br />form and place into a dry cooler. Samples will be delivered to a State-certified laboratory for analysis <br />of constituents listed 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 PID pre-calibrated to isobutylene. <br />4.5. 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 probe boring location. <br />4.6. BORING ABANDONMENT <br />The probe borings will be permanently sealed to prevent vertical migration of potential <br />contaminants. Soil boring shall be abandoned by backfilling with portland cement from the total <br />depth to surface grade. <br />Advanced GeoEnvironmental, Inc.