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20 October 1998 <br /> AGE-NC Project No. 98-0459 <br /> Page 4 of 7 <br /> 4.2. SOIL-VAPOR SAMPLING PROCEDURES <br /> Soil probe borings for soil-vapor sampling were advanced to 5 feet bsg. Each probe boring was <br /> advanced using a van-mounted Geoprobe 5400 probing unit equipped with 1.125-inch diameter.rods. <br /> Soil-vapor samples were collected using a Geoprobe soil vapor assembly. <br /> The vapor sampling assembly consisted of an expendable vapor point placed into a point holder at <br /> the bottom of a string of 1-inch diameter hollow drive rods. The assembly was advanced to the <br /> specified depth and retracted six inches in order to engage the expendable point into the soil and <br /> expose a column of strata from.which the soil-vapor was later extracted. <br /> A post run tubing adapter, equipped with an 0-ring to ensure a vacuum-tight seal, was attached to <br /> a '/4-inch diameter, single-use, disposable polyethylene tubing. The sampling tube was lowered <br /> through the center of the hollow drive rods and secured by threading into the expendable point <br /> holder. <br /> The vacuum pump was used to apply a negative pressure to a Tedlar bag inside a vacuum chamber. <br /> To collect a soil-vapor sample,the sampling tube was attached directly to the Tedlar sampling bag, <br /> through an air-tight port. The vacuum chamber was then sealed, a negative pressure was applied to <br /> the chamber by the vacuum pump. The Tedlar bag filled, allowing the sample to enter directly into <br /> the 1-liter Tedlar bag. On complete collection of the soil vapor sample,the negative pressure in the <br /> chamber was reduced and the sampling bag sealing port was closed. Upon collection, each sample <br /> was labeled, logged onto a chain-of-custody form-and place into a dry cooler. <br /> The vapor samples were transported under chain-of-custody to McCampbell Analytical,Inc. (MAI). <br /> Each sample was analyzed in accordance with: <br /> • EPA Method 8010 for chlorinated hydrocarbons. <br /> 5.0. FINDINGS <br /> 5.1. GROUND WATER DEPTH <br /> The depth to ground water in the borings established for ground water sampling was approximately <br /> 43 feet. <br /> I <br /> i <br /> I <br />