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Mr Michael Infurna <br /> . November 1, 1999 <br /> Page 2 <br /> Low levels of petroleum hydrocarbon constituents were detected in the samples collected from <br /> wells MWl and MW2 MWl contained benzene and TPHg at 7 2 parts per billion (ppb) and 110 <br /> ppb, respectively. MW2 contained benzene and TPHg at 10 ppb and 68 ppb, respectively No <br /> Petroleum hydrocarbon constituents were detected in the sample collected from well MW3 <br /> Analytical data are summarized in Table 2 Laboratory reports and chain-of-custody <br /> documentation are included in Attachment B <br /> CONCLUSIONS <br /> Dissolved benzene and TPHg concentrations in wells MW1 and MW2 have decreased by <br /> approximately 95% or more from their historic high concentrations in 1991/1992 Time vs <br /> Concentration plots of benzene and TPHg for these wells are presented in Figures 3 and 4 Due <br /> to this demonstrated declining trend in dissolved gasoline constituents and the absence of MTBE <br /> in the groundwater, Ground Zero recommends no further action at this site based on the low risk <br /> groundwater designation under Th-Regional Board Staff Recommendations for Preliminary <br /> Investigation and Evaluation of Underground Tank Sites, Appendix B. Appendix B <br /> documentation will be submitted under separate cover <br /> Please contact the undersigned at (209) 838-9888 if you have any questions regarding this report <br />• <br /> Respectfully, p.ED GE <br /> �� p <br /> Ground Zero Analysis, Inc ��`' rD <br /> 0, <br /> (� JOHN P <br /> u, No 6795 <br /> John P Lane <br /> CA Re istered Geolo 1st 6795 F�4 <br /> Gregory P Stahl, RG 5023 GR GO STAHL P. <br /> CA Certified Hydrogeologist 264 No 5023 <br /> Attachments �1g7F OF CA �ip��\P <br /> ,� <br /> CC. Mr Don Peterson John Pestana, QTIP Trust <br /> Mr Mark List, RWQCB Sacramento <br /> pestana OWannual99 doc <br />