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A • ;+tel � ,�-. - - � � � �.. �� - <br /> Field Procedures <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 dill <br /> was employed for penetration prior to using the drive rod. The <br /> entire sampling system was purged with ambient air drawn through <br /> a dust and organic vapor filter cartridge, and a stainless steel <br /> i <br /> probe was inserted to the full depth of the hole and sealed off <br /> F <br /> from the atmosphere. A sample of in-situ soil gas was then with- <br /> - E <br /> drawn through the probe and used to Yu 4e ambient air from the <br /> sampling system. A second sample of soil gas was withdrawn through <br /> Sl — the probe and encapsulated in a pre-evacuated glass vial at two � . <br /> atmospheres of pressure (15 psig) . The self-sealing vial was j <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 with 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 field activities. These QA/QC samples were , <br /> obtained by inserting the probe tip into a tube fleshed by a 20 psi <br /> flow of pre-purified nitrogen and collecting in the same .mannex as <br /> described above. <br /> � ` 4 <br />