Laserfiche WebLink
ElOt® <br /> Mr Jeff Wong <br />' July 28, 2005 <br /> Page 2 <br />' petroleum hydrocarbons as gasoline (TPHg) and total petroleum hydrocarbons as diesel (TPHd) <br /> by EPA Method 8015M, and for methyl tertiary butyl ether(MTBE) by EPA Method 82608 <br />' Cumulative groundwater sampling results are summarized in Table 1 A map depicting dissolved <br /> concentrations of TPHd, TPHg, benzene, and MTBE in groundwater for second quarter 2005 is <br /> included as Figure 4 A copy of the certified laboratory analytical report with chain-of-custody <br /> documentation is included in Attachment C <br />' Conclusions/Recommendations <br /> MW-1 and MW-2 both had reported concentrations of benzene above the laboratory reporting <br /> limits (1 2 pg/L and 1 1 pgIL, respectively) The Equipment Blank sample, however, taken <br /> during the field event, had reported results of benzene, toluene, and xylenes (0 94 pg/L, <br /> 2 1 pg/L, and 2 5 pg/L, respectively) Thus, one or both of the detections of benzene may be <br /> attributable to cross contamination <br /> Reported concentrations in MW-3 have remained below the laboratory reporting limits since the <br /> fourth quarter 2004 event TPHd remained below the laboratory reporting limits in MW-4 for the <br /> • third consecutive quarter Based on the systematic demonstrated natural attenuation through <br /> time in concentrations of the chemicals of concern, groundwater at this site does not pose a <br /> threat to human health or the environment, and in our opinion, this site should be closed from an <br /> environmental standpoint <br /> Future Work <br /> Upon approval of site closure, the groundwater monitoring wells will be properly abandoned or <br /> destroyed in accordance with San Joaquin County Public Health Services Department <br /> requirements <br /> I <br /> ICelebrating 35 Years o/Excellence in Environmental Services <br />