ARCHIVED REPORTS_XR0007449 CASE 1

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k" KLEINFELDER 10 1 6 CONCLUSIONS AND RECOMMENDATIONS ' 6.1 CONCLUSIONS ' Groundwater elevations ranged from a maximum of 2 72 feet above mean sea level (msl) at MW-4 to 1 48 feet above msl at MW-2 Depth to water was measured at approximately 38 29 to 37 38 feet bgs Groundwater flow was towards the southwest with an approximate gradient of 0 004 ft/ft ' No product or sheen was observed from groundwater from perimeter monitoring wells MW-2, MW-3, and MW-4 Approximately one half inch of floating product and a strong petroleum-like odor was noted in the groundwater from monitoring well MW-1 TPH-D, TPH-G, and ethylbenzene were detected in groundwater samples collected from MW-1, located approximately 10 feet down-gradient of the UST area TPH-D was detected at ' concentrations of 17 mg/1 and TPH-G at 2 4 mg/1 Ethylbenzene was detected in groundwater samples collected from MW-1 at a concentration of 2 4 µg/1 No other BTEX constituents were detected in MW-1, including total xylenes, which have been detected in 5 of the 6 previous sampling events None of the requested analytes were detected in the groundwater samples collected from the down-gradient monitoring wells, MW-2 and MW-3, nor from the upgradient well MW-4 The concentration of ethylbenzene found in MW-1 (2 4 µg/1) was found to be well below the ' State Primary Maximum Contaminant Levels (MCLs) for ethylbenzene which is 300 µg/1 Based on the information obtained, it is Kleinfelder's opinion that the groundwater contaminant ' plume is located in the vicinity of MW-1 and the existing UST, and is apparently contained within perimeter monitoring wells MW-2, MW-3 and MW-4 Diesel range product has been detected on the surface of groundwater in monitoring wells MW-1 over the past four quarterly ' events at thicknesses ranging from a film (<0 01 feet) to approximately 33 feet (4 inches) During this second quarter 2003, product was detected in MW-1 at an approximate thickness of 0 04-feet (approximately % inch) Floating product was not detected in the initial five ' groundwater sampling events beginning in June 2000 through June 2002 The appearance of floating product in MW-1 has been observed since September of 2002 Kleinfelder has noted a general decrease in water levels over time in MW-1, which may be a contributing factor of product occurring in monitoring well MW-1 Groundwater elevations from MW-1 in the initial four groundwater sampling events ranged from 4 55 to 6 92 feet The groundwater elevation of the fifth sampling event was 3 18 feet Over the past four sampling events groundwater elevations in MW-1 have ranged from 1 47 to 2 94 feet t 28209 T03/ST03RI312 Page 9 of 1 l ' ©2003 Kleinfelder, Inc September 22,2003