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P r ' 17 August 2012 AGE-NC Project No. 01-0887 Page 5of6 O-ring to ensure a vacuum-tight seal. The adapter assembly is then lowered through the center of the Geoprobe hollow drive rods to the specified depth and secured by threading into the expendable vapor point holder. A stabilization time of 20 minutes will follow boring ' placement. A diagram of the soil vapor sampling tip is presented in Figure 3. -- hlaf ;.VJ0/ Above ground, the surface around the soil vapor sampler will be sealed with a bentonite sealant to prevent ambient air intrusion. The end of the polyethylene tubing is attache a two-way inlet port to a Tedlar 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 tIhi sys em. . e vacuum chamber is then sealed and the vacuum pump is attached to a ly " 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, fog 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 above. --�_ After sample collection, soil-vapor from the polyethylene tubing will be monitored for the presence of volatile organics using a photo-ionization detector (PID) pre-calibrated to isobutylene. Additionally, AGE proposes to utilize 70% isopropyl alcohol (rubbing alcohol) as a leak detection tracer compound to ensure that a reliable soil-vapor sample is collected from each soil boring with no ambient air breakthrough down the probe rods. AGE will apply an appropriate amount of rubbing alcohol(approximately 8 ounces)to adequately wet a cotton towel; the wetted towel will be completely wrapped around the base of the probe rod where it contacts the surface and the bentonite seal. Thereafter, a soil-vapor sample will be collected. Isopropyl alcohol analysis will verify the validity of each sample. EQUIPMENT DECONTAMINATION All sampling tools used for sample collection will be thoroughly rinsed with clean water after being washed with a solution of Alconox. All down-hole drilling and sampling equipment will be pressure washed prior to starting the :boring. All rinseate generated during drilling activities will be containerized in properly labeled DOT-approved 55-gallon drums, and was stored on-site in an area lacking public access. Advanced GeoE n A ro n mental,Inc.