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1 <br /> EIL-It® <br /> Mr Jeff Wong <br />' November 17, 2005 <br /> Page 2 <br />' 8021 B, for total petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as <br /> diesel (TPHd) by EPA Method 8015M, and for methyl tertiary butyl ether (MTBE) by EPA <br />' Method 82608 Copies of the groundwater sampling information sheets are included in <br /> Attachment B <br />' TPHd and TPHg have remained below the laboratory reporting limits in all wells for a minimum <br /> of four consecutive quarters <br />' MW-2 had reported concentrations of benzene only slightly above the laboratory reporting limits <br /> (0 94 pg/L) The benzene concentrations in MW-2 continue to have a downward trend <br />' Cumulative groundwater sampling results are summarized in Table 7 A map depicting dissolved <br /> concentrations of TPHd, TPHg, benzene, and MTBE in groundwater for third quarter 2005 is <br /> included as Figure 4 A copy of the certified laboratory analytical report with chain-of-custody <br /> tdocumentation is included in Attachment C <br /> A graph of TPHd, TPHg, benzene, and groundwater elevation versus time for MW-2 appears as <br /> Attachment D <br /> Conclusions/Recommendations <br /> Based on the systematic demonstrated natural attenuation through time in concentrations of the <br /> contaminants of concern, groundwater at this site does not appear to pose a threat to human <br /> health or to the environment ENSR recommends initiation of procedures leading to regulatory <br /> closure of this site <br /> Future Work <br /> Upon acceptance of the above recommendation regarding site closure, the groundwater <br /> monitoring wells will be properly abandoned or destroyed in accordance with San Joaquin <br />' County Public Health Services Department requirements <br /> • <br /> Celebrating 35 Years of Excellence to Environmental Services <br />