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Troovr R"warah Corporotlon <br /> p.J <br /> k <br /> .rte, <br /> f <br /> a set o:jaws was used to drive and withdraw the sampling probes. A hydraulic hammer was <br /> ! Y used to assist in driving probes past cobbles and through unusually hard soil. <br /> 4� <br /> i <br /> SAMPLING PROCEDURES <br /> Sampling probes consisted of 7 to 14 foot lengths of 3/4 inch diameter hollow steel <br /> ' pipe that are fitted with detachable drive points. Soil gas samples were collected by driving <br /> the steel probe to a depth no deeper than 4 feet into the ground. Once inserted into the <br /> ground, the above-ground end of the sampling probes were luted with a steel reducer and <br /> a length of polyethylene tubing leading to a vacuum pump. To adequately purge the <br /> ' volume of air within the probe, 2 to 5 liters of gas were evacuated with a vacuum Pump• <br /> i l During the soil gas evacuation, samples were collected in a glass syringe by inserting a <br /> syringe needle through a silicone rubber segment in the evacuation line and down into the <br /> =�`4 steel probe. Ten milliliters of gas were collected for immediate analysts in the TRC <br /> analytical field van. Soil gas was subsampled(duplicate injections)in volumes ranging from <br /> 1 uL to 2 mL, depending on the VOC concentration at any particular location. <br /> The shallow groundwater samples collected by TRC were obtained by driving the <br /> ! ' hollow probe with a detachable drive point below the water table and then withdrawing the <br /> probe to permit water inflow into the resulting hole. After placing the probe in position, <br /> ' the above-ground end of the sampling probe was fitted with a vacuum adaptor (steel <br /> reducer) and a length of polyethylene tubing leading to a vacuum pump. A vacuum of up <br /> to 24 inches of mercury was applied to the interior of the probe and open hole for 15 to <br /> 1�9 20 minutes or until water was drawn up the probe. The water thus accumulated was then <br /> ! ' removed by drawing a vacuum on a 1/4 inch polyethylene tube inserted down the probe <br /> to the bottom of the open hole. Loss of volatile compounds by evaporation is accordingly <br /> ? reduced when water is induced to flow into the vary narrow hole,because it can be sampled <br /> with little exposure to the air. The polyethylene tubing was only used once and then <br /> discarded to avoid any cross-contamination problems. <br /> i <br /> 3 <br /> k7s <br />