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Hf II lcl-�-IEBNER <br /> Mr Bill Vizza <br /> 30 November 1993 <br /> Page 7 <br /> been analyzed and found to contain diesel product. Results of this investigation indicate <br /> that the previous finding of diesel product in a water sample collected from the excavated <br /> area is not confirmed. As such it is concluded that the previous finding of diesel product <br /> in water may have been the result of cross contamination during excavation and sample <br /> collection activities. <br /> City of Tracy records specify neither the depth of the excavation nor the level to which <br /> water filled the excavation Groundwater was penetrated at a depth of six feet below <br /> ground surface during this investigation. In order to further demonstrate that petroleum <br /> hydrocarbon product is not present at detectable concentrations within groundwater and <br /> to further evaluate seasonal fluctuations of shallow groundwater levels, we recommend that <br /> one additional set of groundwater samples be collected for analysis during February 1994. <br /> If no petroleum hydrocarbon product is detected by the February 1994 analyses, we will <br /> recommend that the monitoring activities be discontinued and that the three monitoring <br /> wells be properly abandoned <br /> We recommend that you review our results and conclusions with the County. If you have <br /> any questions regarding our conclusions or recommendations, please do not hesitate to call <br /> US. <br /> UNAKA e ��Sincerely yours, B 'o��T0 ; {,�53is <br /> 0 CT <br /> HELMICK & LERNER INC. ED oING oOLO <br /> GEOLOGIST <br /> �`\F <br /> Dennis B. Nakamoto, C.E G <br /> Project Manager <br /> CC. Ms Dianne Hansen - San Joaquin County Health Services <br /> enclosures• Figures 1 <br /> Tables 1,2,3 <br /> Boring Logs <br /> Field Data Sheets <br /> Chain of Custody Forms <br /> Laboratory Analysis Reports <br /> WP 10101\SOIL.-GWT RPT <br /> i <br />