Laserfiche WebLink
� T <br /> ATC Associates Inc. <br /> 1117 Lone Palm Avenue, Suite B <br /> (: <br /> Modesto, California 95351 vYjkTc <br /> 209-579-2221 <br /> ASS OCIATES i N c. fax: 209-579-2225 <br /> MTBE was detected in the groundwater samples collected from MWI, MW4, MW5, MW6, MW7, <br /> and MW8 at concentrations of 12 ug/L, 26 ug/L, 74 ug/L, 240 ug/L, 1.8 ug/L, and 5,100 ug/L, <br /> respectively. TAME was detected in the groundwater samples collected from MW5 and MW8 at <br /> concentrations of 1.4 ug/L and 63 ug/L, respectively. <br /> Analytical results of groundwater samples are summarized in Table 2. Laboratory data sheets and <br /> chain-of-custody documentation are contained in Attachment 2. An isoconcentration map depicting the <br /> MTBE concentrations in on-site wells during the third quarter 2005 is shown on Figure 4. <br /> GEOTRACKER DATA UPLOAD <br /> The facility has been assigned a Geotracker global identification number T0607700120. The depth to <br /> water data was submitted electronically to the State Water Resources Control Board (SWRCB) <br /> Geotracker database (confirmation number 7602436661). The laboratory data was also submitted <br /> electronically to the SWRCB Geotracker database(confirmation number 4369261145). Documentation <br /> of the data submittal is contained in Attachment 3. <br /> CONCLUSIONS <br /> Chemical concentrations from MWI and MW4 through MW8 generally remain consistent with the <br /> results from the previous sampling event. MTBE concentrations decreased in MW4 and MW5. <br /> MTBE and TAME were reported at the highest concentrations to date in the groundwater sample <br /> collected from MW8_ TAME was detected in the groundwater samples collected from MWI, MW5, <br /> and MW8. The direction of groundwater flow was fairly consistent with respect to recent monitoring <br /> events. The gradient on September 30, 2005, was 0.0035 ft/ft or approximately 18.5 i}/mile. <br /> Groundwater elevations have decreased since June 2005. <br /> RECOMMENDATIONS <br /> Based on the results of the third quarter 2005 monitoring episode, we recommend the following: <br /> • Conduct the fourth quarter 2005 groundwater monitoring and sampling of MWI through MW8 <br /> and analyze samples for TPHg and BTEX by EPA Method 8015M/8021B and MTBE,ETBE, <br /> DIPE, TBA,TAME, 1,2-DCA, and EDB by EPA Method 8260B. <br /> • Prepare an Interim Remedial Action Plan to address the MTBE hot spot concentrations. <br /> s:\envimnenW\25847\0037\t�ns�3qr,2005.d- 4 <br />