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[ � KLEINFELDER stored in an Iced chest under chain-of-custody samples les were then submitted to P ' the analytical laboratory for analysis Groundwater samples were analyzed for BTEX, TPH-G, oxygenate analytes (TBA, MTBE, DIPS, ETBE, TAME), and 1,2-DCA 2 2 GROUNDWATER ELEVATION AND WELL DEPTH DATA Free product was not, nor ever has been observed among the wells, based on the measurements obtained utilizing the oil/water Interface probe and/or the visual 1 observations Groundwater elevations Increased approximately 3 21 feet from the previous event performed in October 2004 The elevations ranged from —28 22 to —29 38 feet ms! The groundwater flow direction is easterly to southeasterly at a gradient of approximately 0 004 feet per linear foot The well depth measurements at the air-sparging locations SP-1, SP-4, SP-5, and SP-6 Indicated an appreciable amount of fill material has entered the wells The sparging wells were never Intended to be used for monitoring purposes and were never developed as such Furthermore, the screen placements of these air-sparging wells were selected to facilitate the injection of air Into the subsurface and not the collection of representative groundwater samples The tops of the screens in the air-sparging wells are approximately 20 feet _below the groundwater table If further sampling or remediation activities are to be conducted at these locations, the air-sparging wells will need to be developed 1 2 3 BTEX AND TPH-G ANALYTICAL RESULTS Typical petroleum-hydrocarbons BTEX and TPH-G were detected in the groundwater YP P Y � ) samples from the following wells MW-1, MW-7, MW-11, MW-12, SP-1, SP-2, SP-4, SP- 6, PZ-1, and PZ-2 There were no detectable BTEX or TPH-G concentrations measured in the samples collected from wells MW-5, MW-8, MW-10, SP-3, and SP-5 The benzene concentration increased in well MW-11 The remaining wells remained stable or decreased in benzene concentration The detectable benzene concentrations ranged from 32 micrograms-per-Liter (pg/L) at well MW-7 to 1,700 pg/L at well PZ-1 C23-484517-E3001SAC5R608 Page 7 of 11 September 14, 2005 Copyright 2005 Kleinfeider Inc