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CONESTOGA-ROVERS <br /> &ASSOCIATES <br /> TPHg, TPHd, MTBE, and TBA concentrations ;for soil samples collected after the <br /> 1990 excavation-are shown-on Figures 5 and 6. TPHd and MTBE,isoconcentration contours in <br /> soil are shown on Figure 5, and TPHg and TBA.isoconcentration contours in soil are shown on <br /> Figure'6. As noted'previously, the TPHd and TPHg detections'did°not match the laboratory <br /> standard,but isoconcentration contours were prepared for these constituents to be conservative. <br /> During the first quarter_of 2007, TPHg and BTEX'concentrations were noxi-detect in all site <br /> wells_ TPHd and MTBE were detected only in MW-lA at 51 pg/L and 6.6 µg/L, respectively. <br /> An MTBE isoconcentration contour map is included as Figure'7. _ <br /> 9. Zone of influence calculated and assumptions used for,the subsurface remediation system <br /> and the zone of capture attained for the soil and groundwater.remediation system; ` <br /> No permanent remediation systems have.been installed at the site.. <br /> 10. Reportslinformation; <br /> A table listing known reports is included in Attachment C. All available boring logs and well <br /> construction details are.'included in Attachment B. Table 1 summarizes available soil boring and <br /> well construction information. <br /> 11. Best Available Technology(BAT) used or an explanation for not using BAT; <br /> No formal comparison W remedial technologies has-been completed. at the site, because no = <br /> permanent remediation:system was installed-at the site. . <br /> 12. Reasons why "background"wasrs unattainable using BAT; <br /> MTBE concentrations are continuing to decrease it the site, and background levels are expected <br /> to be attained. <br /> 13. Mass balance calculation of the substance treated versus that.remaining; <br /> .Mass balance calculations were prepared for.TPHg, TPHd; and MTBE remaining in soil at the <br /> site, and for MTBE remaining in groundwater, and are included in Attachment D. <br /> TPHd and MTBE chemical data in soil and isoconcentration.lines showing the estimated areas <br /> ..enclosed by these lines are-presented ori Figure 5. TPHg and TBA chemical data in soil and <br /> 0813 8 <br /> r - -Worldwide Engineering,Environmental,Construction,and IT Services <br />