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Mr Steve Sasson Project 0805-147.04 <br /> October 9, 1997 <br /> Page 2 <br /> Based on groundwater data, dissolved hydrocarbons have been detected in the <br /> groundwater samples collected from monitoring well MW-1 and vapor extraction <br /> well VW-3 Dissolved hydrocarbons were below laboratory detection limits in monitoring <br /> wells MW-2 and MW-3 Historical groundwater flow and gradient has been to the east at <br /> approximately 0 003 <br /> PROPOSED SCOPE OF WORK <br /> The purpose of this investigation is to further delineate dissolved hydrocarbons <br /> downgradient from the USTs Field work will be conducted following Tri-Regional Water <br /> Quality Control Board Guidelines EMCON field procedures are presented in the <br /> appendix EMCON proposes to conduct the following scope of work <br /> PREFIELD ACTIVITIES <br /> EMCON will obtain well permits from the San Joaquin County Public Health Services, <br /> Environmental Health Division EMCON will also notify Underground Service Alert of its <br /> intent to drill at least 48 hours before drilling to identify the location of underground <br /> utilities <br /> FIELD OPERATIONS <br /> EMCON field personnel will observe a licensed well driller drill one 10-inch-diameter soil <br /> boring (B-9) downgradient from the USTs (see Figure 2) near the northeastern property <br /> boundary The boring will be drilled to a depth of approximately 75 feet below ground <br /> surface (bgs) or 15 feet below historical static groundwater level (60 feet bgs) However, <br /> if a 5-foot-thick clay layer is encountered less than 15 feet below static groundwater level, <br /> the drilling will be terminated within the clay unit. <br /> A 4-inch-diameter groundwater monitoring well (MW-4) will be installed in the boring. <br /> The well will be constructed using 0 02-inch slotted screen The 0 02 screen will be placed <br /> from approximately 15 feet below historical low static groundwater and will extend up to <br /> 25 feet above historical low groundwater level Number 3 sand will be used as the filter <br /> pack <br /> Undisturbed soil samples will be collected from soil boring B-9 using the methods <br /> described above A minimum of two soil samples from the boring and a composite sample <br /> from the drill cuttings will be submitted to an approved laboratory certified by the state of <br /> iCalifornia The samples will be analyzed for TPHG and BTEX using modified U S <br /> Environmental Protection Agency (USEPA) Methods 8015 and 8020, respectively. In <br /> SAO N TJ(n0805S08051470 4BS-97\prz l <br />