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1 <br /> Geologtw recFtr a kc Page 5 <br /> Morita <br /> Additional Site Characterization Report <br /> Project No 724 2 <br /> April 19,2004 <br /> ' Well No. Dia./TD Screen Slot Sand PackTransition Grout Seal <br /> (in/ft) Interval (ft) (in) ft Seal (ft) (ft) <br /> 25-42 _Y _ -sur ace <br /> -sur ace <br /> - - - _-sur ace _ <br /> MW--i_ _- sur ace LL <br /> -sur ace <br /> -sur ace <br /> ' =_ _ _ ace <br /> -sur <br /> 64'-surface <br /> - -sur ace <br /> ' Before installing the bentonite seal the wells were bailed using a 2-inch diameter steel bailer <br /> to achieve maximum filter pack density and remove fines A granular bentonite seal was <br /> used in wells screened across the water table at approximately 38 feet bgs A weighted <br /> ' bentonite pellet transition seal was installed above the sand filter pack in the deeper wells <br /> Surface seals were achieved by pumping a neat cement grout (augmented with < 4% <br /> bentonite) through a 1-inch diameter PVC tremmie pipe lowered into the augers The grout <br /> was pumped as the augers were withdrawn to ensure that an integral grout seal was <br /> achieved The wells were secured with locking watertight caps and encased in flush <br /> mounted traffic rated well boxes <br /> The well's constructions are detailed on the boring logs included in Appendix C and in <br /> Table 2 <br /> 3.0 WELL DEVELOPMENT AND SAMPLING <br /> Well MW-202 <br /> ' On December 15, 2003 well MW-202 was sampled after limited well development as stated <br /> above in Section 2 0 The limited well development consisted of bailing the augers of <br /> approximately 20 gallons of water before setting the casing and bailing approximately 10 <br /> ' gallons from the well casing after the filter pack was set These efforts had the effect of <br /> removing some of the coarser silt materials from the casing and settling the filter pack <br /> After removing casing water with a 10 ft long steel bailer lowered on a wire line, a <br /> ' disposable Teflon bailer was used to grab a sample from well MW-202 Water samples <br /> were transferred into 40-m1 VOA vials preserved with hydrochloric acid All samples were <br /> checked for headspace bubbles, labeled, inserted into foam holders and placed into an ice <br /> ' chest cooled to 4°C for transport to the laboratory The sampling technician, while <br /> collecting all samples, wore disposable gloves A chain of custody document, listing all <br /> samples collected and their intended analyses, accompanied the samples from field to the <br /> ' laboratory, thereby providing a means to track their movement and ensure their integrity <br /> The MW-202 groundwater samples were submitted to Sherwood Laboratories in Hilmar, <br /> California (Department of Health Services Certification # 1400) for the following analyses <br />