Laserfiche WebLink
7ti � <br /> Mr Harlin Knoll <br /> Page 3 of 4 <br /> (ppb), 210 ppb, 9 9 ppb, and 2 6 ppb, respectively No MTBE was detected in wells MW2, <br /> MW6, or MW7 Analytical results are summarized in Table 2 The estimated extent of <br /> MT13E in shallow groundwater beneath the site is illustrated on Figure 3 Attachment B <br /> contains laboratory reports and chain of custody documentation for groundwater samples <br /> collected in December 2002 <br /> 4.0 SOIL PILE ANALYTICAL RESULTS <br /> No gasoline or diesel constituents were detected above MDLs in the composite soil sample <br /> collected from the stockpiled soil Soil analytical results are included in Attachment C <br /> Attachment C also contains a summary table of all soil samples collected from the soil <br /> stockpile as well as a map showing sample locations <br /> 5.0 SUMMARY AND CONCLUSIONS <br /> • Groundwater elevations at the site fell an average of 1 83 feet between September 4, 2002 and <br /> December 5, 2002, <br /> • Groundwater beneath the site flowed west-northwest on December 5, 2002 at a gradient of <br /> approximately -P5 feet per mile, <br /> MTBE was the only chemical of concern detected at the site No other gasoline or diesel <br /> constituents have ever been detected in any site well, <br /> • MTBE concentrations in groundwater exceed the primary Maximum Contaminant Level (MCL) <br /> of 13 ppb in well MW3 MTBE exceeds the secondary MCL of 5 0 ppb in wells MWI, MW3 <br /> and MW4, <br /> • The lateral extent of MTBE in groundwater beneath the site has been defined; <br /> • Confirmation soil samples collected from stockpiled soil suggest that uncontrolled soil <br /> aeration has successfully removed petroleum hydrocarbons from the excavated material <br /> RECOMMENDATIONS <br /> Based upon the results of confirmation soil samples, no further remediation of stockpiled soil is <br /> warranted <br /> Since the MTBE plume beneath the site has been defined and appears to be decreasing in <br /> concentration and size, Ground Zero recommends that the San Joaquin County Environmental <br /> Health Department consider closing this site as a low-risk groundwater contamination case <br /> G 1DataIGROUNDZF1Bamyard-Manser\Reports\QMR14QM2002 doc <br />