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i i First Quarter 2006 Groundwater Monitoring Report . Eckert Cold Storage,Manteca,California Page 3 • Table 1 –Groundwater Elevation Data(March 29, 2006) Monitoring Screened Interval(bgs) TOC Elevation) Depth to Water Groundwater Well Elevation MW-1 13 -28 38.09 14.63 23.46 MW-2 15-30 37.90 14.46 23.44 MW-3 15-30 38.31 14.85 23.46 MW-4 12-27 37.84 NM NM MW-5 14-34 41.22 17.87 23.35 MW-6 .13-33 37.65 14.15 23.50 MW-7 13-33 38.22 14.74 23.48 MW-8 1 17-37 37.76--t— NM NASI r TOC Elevation:Elevations are measured from the top of the well casing and are referenced to NGS Benchmark HS4486,elevation 35.03 feet using NAVD 88 datum. NM=Not measured;monitoring wells were covered with a large soil stockpile and therefore inaccessible. All measurements are in feet. LABORATORY ANALYTICAL RESULTS The groundwater samples collected on March 29, 2006 from monitoring wells MW-1 and MW-5 were analyzed for benzene, toluene, ethyl benzene, and total xylenes (13TEX) by EPA Method 826013; total petroleum hydrocarbons quantified as gasoline (TPH-G) by EPA Method 8015M; and selected gasoline oxygenates/additives including methyl tertiary butyl ether (MTBE) by EPA Method 826013. The analytical results for this quarterly sampling event are shown in Table 2, on the following page. Prior to the December 2002 sampling event, historic laboratory analytical results of groundwater samples collected from MW-1 generally indicated elevated levels of contaminant concentrations; though with a decreasing trend. Subsequent laboratory analytical results from the sampling event in March 2005 showed a decrease in contaminant concentration levels. The laboratory results from the current sampling event are consistent with the March 2005 results (see historic groundwater monitoring data, Attachment B). Conversely, prior to the December 2004 monitoring event, historic laboratory analytical results of groundwater samples collected from MW-5 indicated generally very low contaminant concentrations. Laboratory analytical results of samples collected from MW-5 in December 2004, January 2005, and March 2005 indicated' higher contaminant concentrations. Laboratory analytical results of the groundwater sample collected from monitoring well MW-5 during the July 2005 monitoring event indicated that contaminant concentrations had returned to lower levels; these lower levels continued through the September 2005 and January 2006 monitoring events and the current (March 2006) monitoring event. Laboratory certificates of analyses and the chain-of-custody documentation for the samples are included in Attachment D. The samples were analyzed by Argon Laboratories of Ceres, California. 4M �.a CONDOR