ARCHIVED REPORTS_XR0007386 CASE 1

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kn KLEINFELDER 4. GROUNDWATER SAMPLING Groundwater samples were collected during the third quarter 2005 sampling event on September 20, 2005 The groundwater samples were collected from three onsite monitoring wells MW-2, MW-3, and MW-4 at the General Mills facility (Plate 1) 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 each of the four 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 rim of the PVC pipe, ranged from 38 82 feet below top of casing (approximate ground surface) at MW-4 to 39 86 feet in MW-2 Groundwater elevations during the third quarter 2005 sampling event ranged from a high of 1 28 feet at MW-4 to a low of—0 19 feet at MW-2 (Table 1) Groundwater flow direction was calculated to be south by southwest at a gradient of approximately 0 005 ft/ft during the third quarter of 2005 (Plate 2) 4.2 COLLECTION OF GROUNDWATER SAMPLES A total of three groundwater samples were collected from monitoring wells MW-2 through MW-4 during the third quarter 2005 sampling event, which was conducted on September 20, 2005 The wells 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 third quarter 2005 sampling event are Included in Appendix B 28209 T09/5T05R1454/DH iv Page 6 of 12 ©2005, Kleinfelder, Inc November 30,2005