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Page 14 500 West Eleventh Street, Tracy, CA. ]deport: Groundwater-quality Monitoring- June 23-28,2005, 7 M of Concern in Groundwater Mon),Prince al Plume Axis a f al es 4 2 5.1 An as is shown on Figure 3, MW-16 and MW-18, are, groundwater. Wells MW-3, MW-7' Prim plume of affected gr Monitoring axis of the p es of along the approximate long om ared to the concentrations of analytes } arrayed g inspection of Table at C p As can be seen by p o de 2, samples recovered from those nelrall higher les recovered in June 2005 ls in Were generally concern that were found in the gr le, the 2005, the concentrations in the same Well MW 3 rose from 2,300 ed is samples recovered from the same wells. For example, than those measured in the groundwater in Morutori g Well MW-18 concentration of TP detected in Monitoring µg/l, to 5, 100 uglL• The concentration of Ten d rose from 51 µg/L to 65 µg/L over that time p les recovered along the tend a pattern of seasonal increase and neC1ntoein the Those increases in concentrations of ext of concern in sum er g Tri groundwater principal plume axis in June 2005 e regional agricultural e concentrations of fuel hydrocarbons that are related to gr th of analytes of concern to reach a seasonal affected soil in response to the seasonal increases in regi zone of oral concentration irrigation that cause temp summer months. maximum during the 2.5.2 Anal es o f Concern in Ground�'�'ater around Fnn �ofrince al Plume Of the groundwater samples analyses see Table 2) 27 2005 show that, amination of the results of thee -2 and MW-5 on June , on the western Ex Monitoring Wells recovered frons M e 3 had reduced to non- `i -- conditions in March 2005, the concentrations of these along compered to Plume of affected groundwater {see Figur ) rind alp es of concern detected in those wells was fringes of the p p detectable concentrations. The only other analyt oundwater, as was first ations similar to those observed in edMarch 2005. Further s to e MTBE in trace concentr Plume of affect gr round at a =" erimeter of the p north along the western p oundwater-quality inOmtOnnresent in the observed in the results of the March 2005 gr was again found to be p L a trace of MTBE concentration of 0.54 µgf 'concentration of 0.59 [.g[L As was Previously on the development ofta 17 at ated there -upon in MW- well MW-lb. is believed that the MTBE now cin entered near Monitoring groundwater mound that e concentrations of analytes of concern minor differences in the W-10 during the lune There were only relatively 4 MWFP-2� MWF the and M t Monitoring Wells h�lW- results from the March 2005 f:3 detected in aced to the corresponding 2005 same ling round Comp ns along the eastern perimeter of the principal 1 lin round. This indicates that conditions I ` ' sampling affected groundwater at the Navarra Site remain stable. plume groundwater, the unit of the primary plume of affected le recovered At the down-gradient 1 analyte of Concern detected in the sainp between the only to 12 l.g/L concentration of MTBE, 11, fell from a concentration of 14 µWell MW-19, which :. from Monitoring Well MW- groundwater in Monitoring Mar 9, 2005 and Tune 27, 2005. The gr -:-} M anay, continued to be free of concentrations of any is the northernmost well in the sic f