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14 September 1998 <br /> AGE-NC Project No. 98-0454 <br /> Page 5 of 5 <br /> The vacuum pump will be used to apply a negative pressure to the exposed soil column until <br /> approximately three volumes of soil-vapor and ambient air is evacuated through the sampling tube. <br /> To collect a soil-vapor sample,a Tedlar bag will placed into a vacuum chamber. The sampling tube <br /> will be attached directly to the Tedlar sampling bag,through a collapsible,air tight port.The vacuum <br /> chamber is then sealed, a negative pressure is applied to the chamber by the vacuum pump. The <br /> Tedlar bag will be filled, allowing the sample to enter directly into the Tedlar bag. On complete <br /> collection of the gas-vapor sample, the negative pressure-in the chamber is reduced, the sampling <br /> bag sealed. Upon collection, label each sample, log on chain-of-custody and place into a dry cooler. <br /> 4.3. GROUND WATER SAMPLING PROCEDURES . <br /> For the collection of"grab" ground water samples, two probe borings will be advanced to the top <br /> of the ground water table as identified by collection of a saturated soil sample. Once ground water <br /> has been encountered, a Geoprobe push driven water sampling device will be advanced two to three <br /> feet into the water bearing zone. Grab ground water samples'will be collected using a Geoprobe <br /> water sampling assembly or a pre-cleaned one-inch 0.01 slotted temporary well screen. Each ground <br /> water sample will be extracted by lowering a Teflon bailer through the hollow center of the push <br /> rods into the screen section. Samples will be collected in laboratory-supplied, 40-ml VOA vials <br /> containing 0.5-m1 of hydrochloric acid as sample preservative. The labeled vials will be placed in <br /> a chilled container under ice and transported under chain-of-custody to a DTSC-certified laboratory. <br /> 4.4. EQUIPMENT DECONTAMINATION <br /> All sampling tools used for sample collection will be thoroughly rinsed with clean water after being <br /> washed with a solution of Alconox. All probing rods will be cleaned prior to advancement at each <br /> probe boring location. <br /> 4.5. BORING ABANDONMENT <br /> All probe borings will be permanently sealed to prevent vertical migration of contaminants. Soil <br /> borings shall be abandonedbybackfilling with cement slurry from the total depth to surface grade. <br /> Advanced GeoEnvironmental,Inc.' <br />