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rl L <br /> Mr Harlin Knoll <br /> July 27, 1998 <br /> Page 2 <br /> The groundwater sample collected from well MW5 contained elevated levels of petroleum <br /> hydrocarbons, BTEX and TPHG were detected at concentrations of 7,800 parts per billion (ppb), <br /> 5,200 ppb, 840 ppb, 9,000 ppb, and 65,000 ppb, respectively MWl contained BTEX and TPHG <br /> at concentrations of 15 ppb, <0 5 ppb, 6 5 ppb, 62 ppb, and 1,600 ppb, respectively Wells MW4 <br /> and MW8 contained no gasoline constituents above laboratory detection limits Analytical results <br /> are summarized m Tables 2 and 3 Laboratory data sheets and chain of custody documentation are <br /> included in Attachment B Figure 3 shows the estimated extent of dissolved benzene in groundwater <br /> OTHER SITE ACTIVITIES <br /> On June 29, 1998 Ground Zero supervised additional drilling at the site to further investigate the <br /> vertical and lateral extent of soil contamination in the vicinity of well MW5 in anticipation of a request <br /> for site closure One boring was advanced using push-point technology in accordance with a workplan <br /> approved by PHS/EHD Due to refusal of the push rods at a depth of approximately 50 feet bgs, the <br /> proposed scope of work could not be completed The investigation was rescheduled for rind-July and <br /> was completed using a drilling ng equipped with hollow stem augers A report summarizing the results <br /> of the investigation will be submitted under separate cover <br /> The next quarterly monitoring and sampling is scheduled for August 1998 and will include monitoring <br /> depth to water in all site wells, purging and sampling wells MW1, MW2, MW3, MW4, MW5, and <br /> MW8, and analyzing samples for TPHG and BTEX <br /> Please contact John Lane or Greg Stahl at your convenience if you have any questions or comments <br /> regarding the site D G�C�` <br /> Sincerely, <br /> Ground Zero Analysis, Inc g JOHN p <br /> o LANE <br /> No, 6795 <br /> 9A �� <br /> John P Lane OF C <br /> CA Re erect Geologist o 6795 <br /> Gregory P Stahl, RG 5023 GREGORY P. <br /> CA Certified Hydrogeologist 264 STAHL. <br /> No 5023 <br /> JPL <br /> OF C,ALI�,,, <br /> Attachments <br /> cc Mr Carl Knowles <br /> Mr Patrick D Riddle, Esq <br /> Ms Patricia Anderson, CRWQCB Sacramento <br /> groundz6knowles hamlreports12gm1498 dor <br /> r <br />