ARCHIVED REPORTS XR0007789 - Laserfiche WebLink

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1 Gradient was found in this sampling event (Figure 2) to essentially match the gradient from the 16 previous event and was calculated to be approximately 0 002 ft/ft The data collected to date ' support the proposition that groundwater encountered in the existing wells at the site appears to occur under unconfined aquifer conditions 6.2 DISTRIBUTION OF TPH AND BTEX IN UNCONFINED GROUNDWATER TPHd was not detected in any of the groundwater samples taken from the three wells during both sampling events Analysis for TPHd will be maintained for the time being as exploration efforts continue downgradient in the direction of a known diesel fuel contaminated site ' TPHg has been detected in well MW-3 only during both sampling events Concentrations of TPHg in MW-3 have decreased from 48 mg/L in the initial sampling event to 12 0 mg/L found ' during the current sampling event Benzene was found in MW-1 during the initial sampling event to be at a concentration of 2 0 ' ug/L Benzene concentration decreased to below the reporting limit (<0 3 ug/L) in the 24 October 1994 sampling event This decrease would appear to be consistent with the overall lower concentrations of all analytes detected in the wells during the second sampling event Benzene was found in MW-2 during the initial sampling event to be at a concentration of 3 5 ug/L Benzene concentration decreased to 0 72 ug/L in the 24 October 1994 sampling event The decrease appears to be similar to that observed for the other wells ' Benzene was found at a concentration of 13,000 ug/L in MW-3 during the initial event, but had decreased to 8,800 ug/L as analyzed in the 24 October 1994 sample This decrease is consistent with that observed in MW-1 and MW-2 between the two sampling events Toluene was found to be below the reporting limit for the samples taken from wells MW-1 and MW-2 on 24 October 1994 Toluene concentrations decreased in well MW-3 from 7,500 ug/L ' (22 February 1994)to 1,300 ug/L (24 October 1994) Figure 4 presents the geochemical results as obtained by Condor for the initial sampling event, ' whereas Figure 5 presents the geochemical results obtained by RFA for the first quarterly monitoring event 1 Ethylbenzene concentrations decreased in well MW-1, but increased slightly in well MW-2 between the two sampling events The increase of ethylbenzene for MW-2 is not statistically significant as both results are so close to the method reporting limit Concentrations of ethylbenzene and total xylenes in MW-3 for the two events are not comparable due to the difference in reporting limits of the two analytical laboratories for these analytes Total xylene concentrations decreased in well MW-1 and increased slightly in well MW-2 between the two events Results for MW-3 cannot be compared due to differences in reporting ' limits between the two analytical laboratories for the two sampling events ' 366-001 -g_