ARCHIVED REPORTS_QUARTERLY GROUNDWATER MONITORING REPORT 1ST QUARTER-JANUARY 2010

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Wells MW-1 and VE-1 have shallower screened intervals (26-46 feet bgs and 15-35 feet bgs, respectfully). These wells have a groundwater elevation approximately 0.4 feet higher than wells MW-IA through MW-4A. Wells MW-7S and MW-7D are screened over deeper intervals (55-63 feet bgs and 80-85 feet bgs, respectfully). These wells have a groundwater ' elevation approximately 0.1 to 0.2 foot lower than wells MW-lA through MW-4A. The differences in groundwater elevations for wells MW-1, VE-1, and MW-7S/MW-7D, relative to the groundwater elevations for MW-lA through MW-4A are due to the different screened intervals. Wells MW-1, VE-1, MW-7S, and MW-71) were not included in the groundwater elevation contour map presented on Figure 4. ' The Texaco wells, TX-MW-8-50 and TX-MW-14-49 (screened in the "A" zone) and TX-MW-21-80 (screened to 80 feet bgs in the `B" zone), are installed on Site and are used to monitor groundwater for the Texaco LUFT Project. PSC has been granted access to these ' wells for measurement and sampling. Currently, it appears that the groundwater flow for the "A" zone Texaco wells is to the east at a variable gradient of approximately 0.002 to 0.004 foot-per-foot according to the most current data available on GeoTracker, the fourth quarter 2009 report for the Texaco site. It appears that the groundwater flow for the `B" zone Texaco wells is to the southeast at a variable gradient of approximately 0.002 to 0.004 foot-per-foot. It appears that the groundwater flow for the"C" zone Texaco wells is to the south-southeast at ' a variable gradient of approximately 0.002 to 0.004 foot-per-foot. The elevations for the Texaco wells do not correlate with the recently surveyed elevations for the Colombo/Toscana wells. The top of casing elevations for the Texaco wells are approximately 1.5 to 2.0 feet lower than the adjacent Colombo/Toscana wells. Apparently, a different vertical datum was used in the Texaco survey. Therefore, groundwater elevations from the Texaco wells cannot be included with the Colombo/Toscana wells in contouring the groundwater elevation and flow direction. Future monitoring conducted during the Commingled Plume activities, after ' well elevations have been re-surveyed should provide better data to assess deeper groundwater flow. ' 2.3 Analytical Data Laboratory analytical data for groundwater samples collected during this quarterly event are ' presented on Figure 5 and provided in Tables 4 through 7. The following discussion does not include the data collected from the three Texaco wells located on-site. The discussion of the samples collected from the three Texaco wells follows in Section 2.4. ' • TPH-g was detected in groundwater samples collected from eight wells at concentrations ranging from 73 Ng/L in CT-MW-9-120 to 120,000 µg/L,in VE-1. • Benzene was detected in groundwater samples collected from five wells at concentrations ranging from 0.68 µg/L in CT-MW-9-120 to 8,600 Ng/L in well ' MW-7S. The reported concentration in the samples collected from four wells exceeded the California Maximum Contaminant Level (MCL) of 1 µg/L established for drinking water for the concentration of benzene. ' Quarterly Groundwater Monitoring Report First Quarter-January 2010 Prepared For:Sara Lee Bakery Group,Inc. Prepared By:PSC Industrial Outsourcing,LP ' Sara Lee-Lincoln Street\2010_01_QI-QM R(Lincoln).doc May 10,2010 7