ARCHIVED REPORTS_XR0007385 CASE 1

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k'q KLEINFELDER 4. GROUNDWATER SAMPLING Groundwater samples were collected during the fourth quarter 2005 sampling event on December 20, 2005 The groundwater samples were collected from three perimeter onsite monitoring wells MW-2, MW-3, and MW-4 at the General Mills facility (Plate 2) A product skimmer was Installed in MW-1 during the third quarter of 2005 therefore, a groundwater sample was not collected from this well 4.1 MEASUREMENT OF WATER LEVELS In order to evaluate the groundwater gradient at the time of sampling, water level measurements were made in three monitoring wells at the beginning of the sampling event prior to purging and sampling of the wells The depth-to-water was measured in ' each well according to the protocol described In Appendix A, Section A-4 The depth-to- water measurements were converted to groundwater elevations with respect to a local benchmark by subtracting the depth to water measurements from the surveyed casing elevations The groundwater elevations were then used to calculate the direction of groundwater flow and gradient This Information was then used to evaluate which wells represent upgradient and which wells represent downgradient water conditions The depths to water at the three wells (MW-2, MW-3 and MW-4), measuring from the north side of the nm of the PVC pipe, ranged from 39 68 feet below top of casing (approximate ground surface) at MW-4 to 40 35 feet in MW-3 Groundwater elevations during the fourth quarter 2005 sampling event ranged from a high of 0 42 feet at MW-4 to a low of—0 58 feet at MW-2 (Table 1) Groundwater flow direction was calculated to be southwest at a gradient of approximately 0 003 ft /ft (Plate 3) 4.2 COLLECTION OF GROUNDWATER SAMPLES Three wells (MW-2, MW-3 and MW-4) were purged and sampled using disposable bailers and as generally described In Kleinfelder's Protocol (Appendix A) A transparent disposable bailer was partially submerged into the groundwater prior to purging each monitoring well to assess the groundwater for a potential sheen and/or floating product No petroleum odor, floating product or sheen was observed in perimeter monitoring wells MW-2, MW-3, and MW-4 Copies of the monitoring well sampling logs for the fourth quarter 2005 sampling event are included in Appendix B Purge water from the monitoring wells was stored onsite in labeled 55-gallon drums pending chemical analysis and disposal by the Client 28209 T09/ST06R160/CD Iv Page 6 of 12 ©2006 Kleinfelder, Inc February 15, 2006