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r �f <br /> Mr Harlin Knoll <br /> February 23, 200I <br /> Page 2 of 2 <br /> • Groundwater samples were submitted to Argon Laboratories (ELAP #2359) for analysis of TPHg and <br /> BTEX utilizing EPA methods 8015 modified and 8020, respectively <br /> Groundwater Analytical Results <br /> Elevated levels of dissolved gasoline constituents were detected in the groundwater sample collected <br /> from well MW5 and low levels were detected in the sample collected from well MW 1 No gasoline <br /> constituents were detected in the samples collected from wells MW4 or MW <br /> Well MW5 contained TPHg at 100,000 parts per billion (ppb) and benzene at 7,400 ppb NMI <br /> contained TPHg at 250 ppb and benzene at 2 7 ppb Figure 3 presents a benzene isoconcentration map <br /> from the fourth quarter analytical results Analytical results are summarized in Table 3 Laboratory <br /> data sheets and chain of custody documentation are included in Attachment B Attachment C contains <br /> graphical representations of TPHg and benzene concentrations over time in each site well <br /> CONCLUSIONS AND RECOMMENDATIONS <br /> In general, dissolved contaminant levels in well MW5 have been gradually declining since their <br /> recorded high in December 1996 BTEX constituents in well MW5 have declined by 65-77% since <br /> December 1996 Contaminant concentrations in well MW1 have decreased more than 94% from the <br /> recorded highs in that well <br /> • Based upon the historic non-detect results of constituents of concern in wells MW6 and MW7, Ground <br /> Zero recommends destroying those wells under permit from PHS/EHD <br /> Please contact John Lane at (209) 838-9888 if you have any questions or comments regarding this <br /> submittal <br /> Sincerely, ��tk Gt�p <br /> Ground Zero Analysis, Inc <br /> r JOH111J P <br /> 49�. (P G L Nr-_ <br /> No 6795 <br /> <t' <br /> John P Lane =� <br /> CA Registered Geologist 6795 Gr <br /> G <br /> JPL <br /> Attachments <br /> cc Mr Marty Hartzell, CRWQCB Sacramento <br /> Mr Carl Knowles <br /> Mr Patrick D Riddle, Esq <br /> Knowles hwn&eporW3gm2W0 doe <br />