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� # r GEOMATRIX attached to one of several different types of standard drilling rods (minimum 1-inch inside ' diameter for the Enviro Probe, lowered to the bottom of the existing borehole, and advanced (driven or pushed) approximately 2 to 4 feet into undisturbed formation. Internal seals and/or ' check valves create a water-tight sampling tool while in the closed position, so that the Enviro Probe' or HydroPunch' can be used in fluid-filled boreholes. After the sampling tool is emplaced at the target sample depth, the outer sleeve is retracted ' approximately 1 to 1.5 feet (generally 1 foot of retraction for the Enviro Probe' and 1.5 feet of retraction for the HydroPunch'. As the outer sleeve is retracted, subsurface friction retains the drive point in place, exposing the screen section and allowing water to enter the sampling tool. When sampling while using CPT methods, the sampling tool can be attached directly to ' the uninstrumented CPT rods (for the HydroPunch' or 1-inch-inside-diameter rods (for the Enviro Probe' and pushed from the ground surface to the desired sampling depth. The retractable sleeve on both sampling devices ensures that the internal parts are sealed from ' cross-contamination as the tools are advanced. ' 3.1 ENVIRO PROBE' SAMPLING PROCEDURES Groundwater samples are collected by lowering the appropriate groundwater monitoring ' system (GMS) tool down the drive rod (i.e., drill rod or CPT rod). The GMS tools consist of a pore pressure transducer unit (i.e., an in situ pressure transducer with a cable of appropriate ' length and an electronic data logger or other type of read-out unit) and a GMS groundwater sample collection kit. The GMS groundwater sample collection kit consists of sample vials, ' ranging in size from 35 to 1000 milliliters (ml), and a sample vial housing assembly. The sample vial(s) are sealed with a flexible viton rubber septum and cap similar to the upper end ' of the probe. Prior to collecting a groundwater sample, the pore pressure unit is connected in series with the sample vial housing via an arrangement of double-ended hypodermic needles. ' After the housing and pore pressure unit have been connected, the sample vial is evacuated with a hand vacuum pump. Sampling and pore pressure measurements are obtained by lowering the pressure transducer unit and housing assembly down the drive rod. The tools connect to the Enviro Probe' via a quick-coupling system through the hypodermic needles, DISCRETE-DEPTH SAMPLING Page 3 of 6 ' MSC\PROTO-DS.= REVISION DATE:MARCH 1996 DS-3