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. Section No 6 <br /> Revision No 0 <br /> Date September 5, 1991 <br /> Page 4 of 55 <br /> driven to the sampling depth using a heavy duty hydraulic hammer mounted on <br /> 1988, Ford F-450 flat-bed duallys. These rigs are capable of driving <br /> sampling pipe to a depth in excess of 50 feet under normal driving <br /> conditions The drive point rigs are also equipped with hydraulic <br /> outriggers, pipe racks and steam cleaner The probes are removed using a <br /> hydraulically activated pulling dog Latex gloves are worn during handling <br /> and assembling of the sampling apparatus <br /> 6 2 1 2 Sampling Adaptors - Soil gas samples are collected from the <br /> probes via adaptors constructed of stainless steel pipe caps brazed to <br /> stainless steel tubing connected to an inline stainless steel bellows valve <br /> 6 2 1 3 Soil Gas Cartridges <br /> Soil gas samples are collected in stainless steel cartridges housing a <br /> glass tube (Supelco) filled with a three layer packing of various types of <br /> adsorptive hydrophobic carbon The soil gas is passed through these layers, <br /> the first, Carbotrap, absorbing "heavy" volatiles such as dichlorobenzene, <br /> the second, Carbopack B, the lighter volatiles such as TCE and ACE, and the <br /> third, Carbosieve III, the ultralights such as methylene chloride or vinyl <br /> chloride Because the most mobile constituent, vinyl chloride, has a <br /> breakthrough volume of 158 liters , these cartridges are rated to absorb at <br /> least 158 liters of soil gas before breakthrough of any of the priority <br /> pollutants listed in EPA method 601, 602, or 624 Table 2 shows some <br /> breakthrough volumes for the types of carbon sorbents making up the <br /> iadsorption cartridge Thus the sampling capacity of this technique far <br /> 6-4 <br />