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s ( � <br /> r 1 1117 Lone Palm Ave., Suite B <br /> Modesto, California 95351 <br /> j www.atc-enviro.com <br /> 209.579.2221 <br /> Fax 209.579.2225 <br /> A S S O C I A T E S I N C -_ <br /> DEC 1 1 2002 <br /> December 6, 2002 ENVIRONMENT HEALTH <br /> 54.62580.0001 PERMIT/SERVICES <br /> Mr. Chris Colbert <br /> Advanced Interconnect Technologies <br /> 555 Carnegie Street <br /> Manteca, California, 95336 <br /> Subject: Semi-Annual Self-Monitoring Report, Third Quarter 2002 Groundwater <br /> Monitoring at 555 Carnegie Street, Manteca, California <br /> Dear Mr. Colbert: <br /> • ATC Associates Inc. is pleased to provide Advanced Interconnect Technologies with the results <br /> of the groundwater monitoring conducted at the above referenced site (Figure 1). The semi- <br /> annual monitoring was performed as part of a self-monitoring program initiated by Advanced <br /> Interconnect Technologies in June 1995. Monitoring was performed to determine the <br /> groundwater flow direction and the hydraulic gradient in the uppermost aquifer. Sampling was <br /> performed to monitor the distribution of priority pollutant metals in groundwater. <br /> DEPTH TO WATER MEASUREMENTS <br /> ATC Associates performed the depth-to-water measurements on September 20, 2002. Field <br /> work during this event consisted of measuring depth-to-water and collecting groundwater <br /> samples from the three existing monitoring wells, MW-I, MW-2, and MW-3. Field notes are <br /> contained in Attachment 1. <br /> ATC compiled groundwater gradient data from September 20, 2002 to provide an indication of <br /> the direction of groundwater flow in the vicinity of the site. Top of casing elevations and depth- <br /> to-water measurements were used to calculate the elevation of groundwater in each well. Water <br /> levels ranged from 19.60 to 21.20 feet below the tops of the well casing elevations, representing <br /> an average decrease in the water table elevation of approximately 3.92 feet since March 6, 2002. <br /> The water level data were used to develop the groundwater elevation contour map (Figure 2). <br /> Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer <br /> beneath the site flowed generally towards the north with a hydraulic gradient of 0.004 ft/ft or <br /> • approximately 23 feet per mile. This is consistent with previous monitoring events. Groundwater <br /> data are presented in Table 1. <br /> w:\62580\reports\3rdgtr02.doe <br /> ENVIRONMENTAL. GEOTECHNICAL AND MATERIALS PROFESSIONALS <br />