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28 Apri12003 <br /> AGE-NC Project'No. 98--0440 <br /> Page'4 of 7 <br /> 2.8. WELL HEADSURVEY <br /> On 4November 2002, a California state-licensed survey engineer from Baumbach &Piazza, Inc. <br /> surveyed a reference point on the top of ground water monitoring wells MW1, MW2 and MW4 <br /> through MW10 to the.nearest 0.01-foot-relative to the San 7oaquin.County Bench Mark #Z-39 at <br /> 44.076 feet above mean,sea level (MSL). The results of tk e monitoring well survey are contained <br /> 'in Table 1. The surveying report (Baurnbach &Piazza) is presented in Appendix D. <br />' 3A. FINDINGS " <br />' Soil stratigraphy, ground water elevation, flow direction;and gradient were determined from field <br /> data collected on12 December 2002;the contaminant impact to soil and ground waterway quantified <br /> .'by the laboratory analytical data. <br /> 3.1. STRATIGRAPHY <br /> Damp to saturated, gray to brown, silty sand was encountered at 10 feet and 20 feet.bsg in borings <br /> MW7 and MW8 (Appendix A)'. Dry to saturated,brown, silty clay and clay were encountered at all. <br />' other depths in borings.MW7 through MW10. <br /> Organic vapor was not detected in the soil samples collected. PID data is included on the boring logs <br />' {Appendix A}. , <br /> 3.2.; GROUND WATER.GRADIENT AND FLOW DIRECTION <br /> ' Depths to ground water ranged from 12.90 feet to 13.77 feet below the well casing tops. Ground . <br /> water'elevations at the,site ranged from 26.33 feet above mean sea level (MSL) in well MWS to <br /> 27.34 feet above MSL in well.MW L Ground water'elevations'at the site decreased an average of <br /> 1 83 feet between the September 2002 and December 2002 sampling events. Ground water levels <br /> I were within the screened intervals of all the monitoring.wells on-site. <br /> ". The ground water'.flow direction was inferred usingground,water elevatiori data:The ground water <br /> at the site on 12 December 2002 was inferred to have been flowing to the northeast under an average <br /> gradient of 0.006 feet/feet across the area'monitored.Figure 4-illustrates the ground water elevation <br /> Icontours. ' <br /> Advanced GeoEnvironmenfal,Inc. <br />