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' GeoHydrologic Consultants, Inc
<br /> rate of approximately 2 75 gallons per minute The maximum drawdown observed at the
<br /> ' end of the test in EW-5D was approximately 22 8 feet which corresponded to a water
<br /> level of approximately 73 feet deep Measurable drawdown was observed in observation
<br /> wells MW-5 (maximum drawdown 0 32 feet), TB-I 1 (maximum drawdown 0 02 feet),
<br /> TB-10 (maximum drawdown 0 16 feet), MW-4 (maximum drawdown 0 11 feet), and in
<br /> TB-7 (maximum drawdown 0 18 feet)
<br /> ' Vapor samples were collected during the multi-phase extraction test (031705ST,
<br /> 031705M, and 03170505FN) from the total undiluted inlet along with groundwater
<br /> samples collected from the pump discharge (031705ST and 031705FN) Vapor samples
<br /> ' were analyzed by Associated Laboratories of Orange, California (Associated) for TPHg,
<br /> BTEX, and MTBE using EPA Methods 8015 Modified and TO-15, along with
<br /> oxygenates (DIPS, ETBE, TAME, and TBA) and fixed gases (oxygen, carbon dioxide,
<br /> and methane) Groundwater samples were analyzed by Associated for TPHg, BTEX, and
<br /> MTBE using EPA Methods 8015 Modified and 8260B including other oxygenates
<br /> (DIPE, ETBE, TAME, and TBA) The laboratory analytical results are summarized in
<br /> ' Table 6 (vapor) and Table 7 (groundwater)
<br /> A total of three vapor samples (six tedlar bags) were taken for laboratory analysis from
<br /> well EW-5D on March 17, 2005 The concentrations of TPHg were detected at 28 ppmV
<br /> from sample EW-5D-031705ST, 18 ppmV from sample EW-5D-031705M, and 24 ppmV
<br /> from sample EW-5D-031705FN The concentrations of benzene were detected at 0 725
<br /> ppmV from sample EW-5D-031705ST, 0 175 ppmV from sample EW-5D-031705M, and
<br /> 0 317 ppmV from sample EW-5D-031705FN The concentrations of MTBE were both
<br /> below the laboratory MDL (0 001 ppmV) in the middle and final samples and at 0 093
<br /> ppmV from sample EW-5D-031705ST The three samples were analyzed for the fixed
<br /> gases oxygen, carbon dioxide, and methane Sample EW-5D-031705ST was found to
<br /> have 20 05%oxygen, samples EW-5D-031705M and EW-5D-031705FN had detections
<br />' of 20 07% oxygen, while methane and carbon dioxide for the three tested samples was
<br /> below the method detection limas (0 2%) The results are summarized in Table 6 The
<br /> vapor concentrations appeared to decrease slightly in the total influent from the start of
<br />' the combined test performed on EW-5D (28 ppmV TPHg) to the middle of the combined
<br /> test (18 ppmV TPHg) then an increase was recorded at the end of the combined test (24
<br /> ppmV TPHg) EW-5D inlet concentrations measured in the field with a calibrated photo-
<br /> ionization detector (PID) fluctuated throughout the duration of the test, however the final
<br /> concentration (non-detect) was less then the initial concentration (690 ppm) taken at the
<br /> start of the test
<br /> The pump discharge groundwater sample results indicated that moderate to elevated
<br /> concentrations of TPHg, BTEX, and MTBE were detected Concentration for TPHg in
<br />' groundwater at the beginning of the test was recorded to be 147,000 pg/L and at the end
<br /> of the test it was 171,000 µg/L A decreasing trend was observed for benzene (5,090 µg/L
<br /> to 4,200 gg/L), toluene (15,700 µg/L to 14,400 µg/L), an increasing trend was observed
<br />' for ethylbenzene (2,060 µg/L to 3,240 µg/L), and xylenes(11,900 µg/L to 18,300 µg/L)
<br /> MTBE indicated a decrease from the start (418 µg/L) to the finish {267 µg/L) of the test
<br /> on EW-5D A total of approximately 1,320 gallons of hydrocarbon-affected groundwater
<br /> were extracted during this test at an average extraction rate of 3 25 gallons per minute
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