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\TJ%T, <br /> r <br /> A S S O C I A T E S I N C <br /> { <br /> The total amount of groundwater recovered during the remedial action events will be recorded using a flow <br /> meter/totalizer. This will',be used to determine the total.number of gallons extracted during the event. Depth to <br /> groundwater measurements will be collected from surrounding observation wells at periodic time intervals. <br /> Effluent water samples shall be collected during the pumping test. Additional sampling may be required by <br /> conditions of a discharge permit. If water is being stared in a holding tank, appropriate samples will be <br /> collected per disposal requirements. The water will be discharged under proper permit to the local sanitary <br /> sewer system or off-site at a liquid recycling facility. <br /> i <br /> The high vacuum dual phase extraction remedial action will be conducted using mobile extraction equipment <br /> having a liquid-ring blower and associated flow rate and pressure measuring equipment. A thermal oxidizer <br /> will be utilized to treat the extracted vapors. The high vacuum dual phase extraction;remedial action will be <br /> performed in general accordance with ATC's Standard Operating Procedure — High Vacuum Dual Phase <br /> Extraction, which is included in Appendix A. Following completion of the high vacuum dual extraction <br /> remedial action,ATC will evaluate the information and provide recommendations. <br /> Ground Water <br /> L <br /> Petroleum hydrocarbonshave not been detected in groundwater samples collected from MW-3 and MW-4 for <br /> several years. Petroleum hydrocarbons have never been detected in groundwater samples collected from MW-5, <br /> MW-6, and MW-7. Low,concentrations of petroleum hydrocarbons were detected in the groundwater samples <br /> collected from MW-1 and MW-2 in October 2003. MTBE was detected in the groundwater sample collected <br /> ; benzene, toluene, and MTBE were detected in the <br /> from MW 1 at a concentration of 7.1 µg/L. TPHg <br /> groundwater sample collected'from MW2 at concentrations of 190 gg/L, 1.2 gg/L,' 2.5 µg/L, and 21µg/L, <br /> respectively. Concentrations of petroleum hydrocarbons in groundwater samples collected from MW-1 and <br /> MW-2 are within the historical range as established by previous sampling events but have generally decreased <br /> with time. The lateral extent of the hydrocarbon plume in groundwater appears to be receding. Natural <br /> Lattenuation of the petroleum impacted groundwater is recommended. <br /> i <br /> If you have any questions or require additional information,please contact us at(209) 579-2221. <br /> 1 <br /> h Sincerely, <br /> t Todd Hafner Jeanne Homsey,P.E. <br /> Project Geologist CA Registered Civil Engineer No. 47410 <br />,. cc: Ms. Lori Shields, Diesel Performance <br /> ? �.�':r+:ice✓:f I <br /> Ms. Lori Duncan, SJCEHD <br /> Mr. Jim Barton RWQCBs�c <br /> NIS <br /> Diesel Performance '-�^ r ��� January 5,2004 <br /> ATC Project Number 5462577 Page 8 <br /> t <br />