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1 v <br /> 0 El <br /> I <br /> A S S D C I A T E S I N C <br /> Groundwater Analytical Results <br /> TPHg and BTEX were detected above laboratory method detection limits in the groundwater <br /> samples collected from wells MW1 and MW3 Concentrations of TPHg and BTEX on February <br /> 13, 2003 had decreased significantly since the December 2002 monitoring event This is likely <br />' due to the operation of the vapor extraction system and the groundwater treatment system <br /> Groundwater samples were collected from wells MWI and MW3 during the quarterly <br /> groundwater monitoring event on March 7, 2003 and concentrations of TPHg and BTEX <br />' continued to decline A summary of analytical results is presented in Table 3 Groundwater <br /> laboratory data sheets and chain-of-custody documentation are contained in Attachment 2 <br />' REMEDIATION SYSTEM EVALUATION <br /> Vapor Extraction System <br /> From December 27, 2002 to March 27, 2003, the vapor extraction system was operational for <br /> approximately 1,681 hours During that time, the average extracted vapor flowrate was 79 cubic <br /> feet per minute (cfin) and the average influent vacuum achieved by the thermal oxidizer was 12 5 <br /> inches of mercury, based on the information contained on the field monitoring data sheets <br /> contained in Attachment 3 <br /> Based on influent flowrate of 79 cfm, average influent concentration of TPHg of 2,033 ppmv, <br /> and using the values supplied by SunStar Labs of 24 5 liters of vapor per mole of TPHg and a <br /> molecular weight of 86 27 grams per mole of TPHg yields <br /> = 2,0331 TPHg x 79 ft3 x 60 min x 28 32 t air x 1 mole TPHg x 86 27 g x 1 Ib <br /> 1,000,0001 air min 1 hour 1 ft3 24 51 vapor mole TPHg 4549 <br /> = 2 11 lb TPHg x 1,689 hours = 3,558 lbs of TPHg during first quarter 2003 <br /> hour <br /> Total TPHg removed via vapor extraction since system startup on December 19, 2002 <br />' = 400 Ib TPHg fourth quarter 2002 + 3,558 lbs of TPHg during first quarter 2003 <br /> = 3,958 pounds of TPHg removed since the startup of the system <br /> The same calculation for benzene with 24 5 liters of vapor per mole and a molecular weight of 78 <br /> grams per mole is shown below <br /> = 6 51 benzene x 79 ft3 x 60 min x 28 32 t air x 1 mole benzene x 76_q_ x 1 Ib <br /> 1,000,0001 air min 1 hour 1 ft3 24 51 vapor mole benzene 454 g <br />' = 0 006 Ib benzene x 1,681 hours = 10 lbs of benzene during first quarter 2003 <br /> hour <br /> w Iwordprol625961qu,%Ayl1qr-2003 doe 6 <br />