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Field Procedures <br /> f <br /> Soil gas samples were collected at a total of 24 locations at <br /> the site, as shown in Figure 1. To collect the samples a 1/2 inch <br /> hole was produced to a depth of approximately four feet by using <br /> a drive rod, where pavement was present, an electric hammer drill <br /> was employed for penetration prior to using the drive rod. The <br /> entire sampling system was purged with ambien ' air drawn through <br /> a dust and organic vapor filter cartridge, and a stainless steel <br /> probe was inserted to the full depth of the hole and sealed off <br /> from the atmosphere. A sample of in-situ soil gas was then with- <br /> drawn through the probe and used to purge ambient air from tiie <br /> sampling system. A second sample of soil gas was wit drawn through r <br /> the probe -and encapsulated in a pre--evacuated glass vial at two <br /> atmospheres of pressure (15 psig) . The self-sealing vial was . <br /> detached from the sampling system, packaged, labeled, and stored <br /> for laboratory analysis.. <br /> Prior to the day's field activities all sampling equipment, <br /> drive rods, and probes were decontaminated by washing with soapy <br /> distilled water and rinsing wiih distilled water. Internal sur- <br /> faces were flushed dry using pre-purified nitrogen, and external <br /> surfaces were wiped clean using clean paper towels. <br /> Field control samples were collected at the beginning and the <br /> end of the day's fieldactivities..__.__These, ------ <br /> obtained by inserting the probe tip into a tube flushed by a 20 psi <br /> fF <br /> flow of pre-purified nitrogen and collecting in the same manner as <br /> described above. <br /> 4 <br />