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GEOSYNTEC CONSULTANTS <br /> ' Ms. Amy Terrell <br /> 5 October 2004 <br /> Page 6 <br /> Field Methods—Direct Push Grab Groundwater Samptinj <br /> CPT and grab groundwater sampling are proposed for the onsite exploration of <br /> deeper groundwater. Direct push grab groundwater samples are also proposed at three <br /> ' locations downgradient of MW-5 and possibly on upgradient and offsite properties to <br /> the west of the site. These samples may be collected using CPT or Geoprobe direct <br /> push equipment. <br /> General methods and procedures that will be followed for CPT and grab <br /> ' groundwater sampling are summarized below: <br /> • At the cleared location, the CPT cone will be pushed using a CPT rig with a <br /> down pressure capacity of about 25.5 tons. The following parameters will be <br /> measured continuously and averaged over 5 cm (0.16 ft) depth intervals in each <br /> hole: tip resistance (Qt); sleeve friction (Fs); and, dynamic pore pressure (Ut). <br /> Subsurface stratigraphy will be interpreted using relationships between these <br /> parameters. <br /> ' To help identify water-producing zones, dissipation tests will be run as <br /> warranted to estimate the soils capacity for equilibrating pore pressure. <br /> • If a permeable zone is identified during the CPT, then groundwater samples <br /> will be collected. Groundwater samples will be collected by pushing clean, <br /> ' stainless steel Hydropunch rods at a location immediately adjacent to the CPT <br /> hole. <br /> ' All groundwater samples will be poured into sample bottles supplied by <br /> Calscience Laboratories, Inc. of Garden Grove, California, the laboratory that <br /> will perform the analyses. Samples will be placed in a cooler with ice for <br /> ' shipment to the lab and handled under standard chain-of-custody procedures. <br /> • The CPT hole will be grouted using a grout collar process. This process <br /> ' continually grouts the CPT hole with a bentonite grout as the CPT rods are <br /> advanced. When the CPT rods are retracted, the bentonite grout fills the void <br /> ' occupied by the rods and the hole is tremmie grouted as the rods are pulled to <br /> • P:\PRJ2003REM\Wilbur-Ellis\Wc0250(JTF)\STOCKTON\S LF Oct 2004 Work Plan\Oct 04 Work Planb.doc <br /> RECYCLED AND RECYCLABLE <br /> r <br />