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1 <br /> ' Mr Terry Tarchti <br /> October 13, 2005 <br />' Page 3 <br />' Laboratory reports for the groundwater samples collected for these sampling <br /> events are included as Attachment B <br />' Analytical laboratory Ki£f Analytical, Inc, <br /> Davis, California <br />' (California Department of <br /> Toxic Substances Control <br /> Certification No 2336) <br />' Sample exceptions None <br /> Shallow groundwater gradient 0 002 <br /> Shallow groundwater flow direction Northwest <br /> Average depth-to-water 74 64 feet <br />' Average change in shallow groundwater <br /> elevation from 2nd qtr (2005) to 3rd qtr (2005) -5 00 feet <br /> DISCUSSION <br />'. Based on the Hurd quarter's data, the groundwater hydraulic gradient changed <br /> slightly to the northwest under a hydraulic gradient of 0 002, as shown in Figure 2 <br /> Fluctuations in the hydraulic gradient are not uncommon for this site Table 2 <br /> 1 summarizes quarterly measurements of the hydraulic gradient <br /> The on-site supply well has been sampled on a quarterly basis since November <br /> 2002 and has never contained any detectable concentrations of any constituents of <br /> concern Therefore, sample results from this well are not included in the <br />' discussions below In addition, concentrations of 1,2-DCA and EDB have not <br /> been detected and are not included in the discussion below <br />' BTEX The reporting ltnuts for all constituent concentrations in MW-1 were <br /> diluted due to known high concentrations of MtBE The dilutions were necessary <br /> because the MtBE concentrations were out of the calibration range for the target <br />' constituent The reporting limits remained the same for wells MW-2 and MW-3 at <br /> 0 5 micrograms per liter (µg/L) but was decreased to 0 9 in MW-4 due to <br /> concentrations of MtBE BTEX concentrations were below their respective <br />' reporting limits in all of the wells consistent with previous quarters Per <br /> PHS/EHD's request, Brown and Caldwell worked with the analytical laboratory to <br /> determine when it is feasible to quantify the BTEX constituents without damaging <br />' the equipment, especially in samples from MW-1 <br />' This report atts prepared in cia ordann oath the standards of the emaronmental consulting industry at the lime a war prepared It should not he <br /> rehed upon by paries other than those for whom it uus prepared and then on#to the eatent f the scope of work whah nws authorrtied Thrr <br /> report does notguaruntee that no addtkonal enczronmentdl contamination heyond that dercrrbed in this report evris al the sue <br />' P\27000\127960 T&T Truckmg GW Momtunng 2005\Reports\3rd-[15gtr doc <br />