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/(1cayton <br /> • Ms Devra Lewis Page 4 <br /> Regional Water Quality Control Board Clayton Project No. 70-03759.00 <br /> September 3, 2004 <br /> hydrocarbons were not detected in any of the groundwater samples from the monitoring <br /> wells. During the August sampling event, low concentrations (just slightly above the <br /> detection limits) were detected in two wells, MW-2 and MW-5. A maximum of 0.12 <br /> mg/L TPHer was detected in MW-5. No BTEX constituents were detected in any of the <br /> groundwater samples. Groundwater flow during the sampling events was easterly, thus <br /> well MW-2 is located up-gradient of the excavation area, and MW-5 is located <br /> downgradient. As with the grab groundwater samples, these results appear to be <br /> anomalous, as the concentrations are very low, and appear in both up and downgradient <br /> monitoring wells. Two groundwater samples collected from the base of the excavation in <br /> October 2003 did not contain detectable hydrocarbons. Groundwater analytical data is <br /> presented in Table 2, and groundwater analytical data are presented on Figure 7. <br /> 4.0 CONCLUSION <br /> The soil and groundwater results from the pipeline alignment within Neighborhood E <br /> indicate successful removal of soil impacted by petroleum hydrocarbons. Groundwater <br /> results following soil excavation contain either no detectable hydrocarbons or very low <br /> concentrations. Trimark, the owner of the property within Neighborhood E, has <br /> • requested a letter from the RWQCB regarding the status of the investigation and <br /> remediation at the site. <br /> If you have any questions regarding the contents of this letter,please feel free to call us at <br /> 925.426.2600 <br /> Sincerely, ._cRED Gr <br /> tiICHARL HURD <br /> Nli. Cosa <br /> CE,R i ISD <br /> HYDR03E0L061ST <br /> Mich 1 urd, CHG 0068 <br /> Senior Project Manager s E^R• <br /> CIT <br /> • <br /> S:IESTROMCPS120 M759 Shell Mou Houee\GW kn mghb.,ho Esu .yry u ne,y, &c <br />