Laserfiche WebLink
07 July 2003 <br /> �- AGE-NC Project No. 95-0167 <br /> Page 3 of 4 <br /> BTEX compounds were detected in the water samples collected from monitoring wells MW-11, <br /> — MW-2 and MW-3; the highest concentrations were detected in the sample from MW-I at 770 pg/l <br /> benzene, 470 µg/1 toluene, 330 µg/1 ethylbenzene and 1,140 µg/1 xylenes. <br /> — 'MTBE was detected by EPA Method 8260B in samples MW-1 and MW-2 at concentrations of <br /> 50 µg/l and 7.0 gg/l, respectively. <br /> No other fuel additives were detected at or above laboratory detection levels in the ground water <br /> samples. Analytical results of ground water samples collected during the March 2003 monitoring <br /> event are summarized on Tables 2 and 3.The laboratory report(CTEL Project No: CT214-0303048), <br /> — QA/QC report and chain-of-custody form are included in Appendix C. Figure 4 depicts the estimated <br /> lateral distributions of dissolved TPH-g and benzene in ground water. <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> Data collected at the site indicates that: <br /> • The ground water flow direction during this monitoring event was toward the west-northwest <br /> at an average gradient of 0.008 ft/ft. Ground water flow at the site has historically been <br /> towards the northwest. Ground water flow direction is not well defined south of the former <br /> UST area. <br /> • Relatively high concentrations of TPH-g and BTEX occur in ground water in the area of <br /> — monitoring wells MW-I and MW-2;BTEX compounds were detected in MW-3 for the first <br /> time since November 2000; the TPH-g and BTEX concentrations in well MW-1 were the <br /> lowest detected since monitoring was initiated in July 1999 <br /> — • MTBE was present in monitoring wells MW-1 and MW-2 at concentrations of 50 lig/l and <br /> 7.0 �ig/l, respectively. <br /> • The contaminant plume appeared to be confined to the general area of the former UST <br /> location and MW-1 and MW-2. Petroleum hydrocarbons were not detected in perimeter <br /> wells MW-4, MW-5 and MW-6, while low concentrations of BTEX compounds were <br /> -- detected in down gradient well MW-3 this quarter.In addition,petroleum hydrocarbons were <br /> not detected in a grab ground water sample collected and analyzed in April 1997 from soil <br /> boring P4, south of the former UST location. <br /> Advanced GeoEnvironenent2l,Inc. <br />