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i1M KLEINFELDER ' 5 SUMMARY AND RECOMMENDATIONS ' Groundwater monitoring has been conducted at this facility since 1987 to evaluate groundwater quality A summary of the current site conditions and a recommendation for subsequent work are as follows ' • During this event, the average depth to groundwater among the wells was 48 68 feet bgs (-32 01 feet msl) The groundwater flow was generally easterly to southeasterly at a gradient of approximately 0 003 feet per linear foot 0 The total depth measurements indicated that an appreciable amount of sediment ' has infiltrated the air-sparging wells SP-1, SP-5, and SP-6 To conduct further sampling or remediation activities at these locations, the air-spargmg wells will ' need to be developed • The benzene concentrations appear to be increasing in down-gradient wells Concentrations in the suspected source area appear to be increasing as well This may be strongly influenced by the variations in groundwater elevations • The current BTEX concentrations were evaluated against the California Drinking Water MCLs Based on the current groundwater monitoring data, the MCL for ' benzene was exceeded in wells MW-1, MW-7, MW-11, MWA 2, SPA, SP-4, SP- 6, PZ-1, and PZ-2 The MCL for toluene and xylenes were exceeded in well SP- ' 1 - • The TPH-G concentrations appear to be increasing in wells MWA 1, MWA 2, SP- 1, SP-4, and PZ-1 The remaining wells remained stable or decreased in concentration ' • The oxygenate DIPE was detected in wells MW-7, SPA, and PZ-1 The oxygenate reporting limits were elevated in MW-1, PZ-1, and PZ-2, due to ' interferences 11rnifs were, alsa 'cicvaktd -,�r,. mid-'%, SP-1l ¢nd SP-7-, VPt I© • The analyte 1,2-DCA was detected in wells MW-5, MW-7, MW-8, MW-10, MW- 12, and SP-5 1,2-DCA was a component of gasoline during the 1980's Based C23-484517-B001SAC5R540 Page 12 of 14 August 11, 2005 ' Copyright 2005 Kleinfelder, Inc