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Bank of Stockton - Cutter lumber Site Page 4 Quarterly Groundwater Monitoring Report Project No. 102.2 February 9, 2006 labeled, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. ' Gasoline contaminated purge & rinseate water generated during the activities described above was stored in poly drums located on the site. American Valley Waste Oil will remove this material prior to the next scheduled depth to water measuring event. 2.2 Groundwater Sample Analyses Groundwater samples were analyzed as follows: • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 503018015(m). • Benzene Toluene, Ethylbenzene and total Xylene (BTEX) and MTBE by EPA method 602 The detection limits are included in the summary analytical data table (Table 2). Detectable levels of gasoline range petroleum hydrocarbons and/or BTEX compounds were found in all 5 water samples that were collected. The sample from MW-10, however, is anomalous. The sample contained 110 ppm of hydrocarbons, but no BTEX compounds. According to the lab, the distribution on the chromatogram is anomalous, and not typical of gasoline nor other lie samples from this site. We interpret that some non-gasoline contaminant may have been introduced into the well from Cutter Lumber operations- Future sampling events will be needed to more fully assess this sample point. 2.3 Field Data The field data for this groundwater monitoring event are summarized in Appendix B and Table 1. The level of groundwater has change little since the groundwater monitoring event completed on September 19, 2005- The bearing ' and gradient of groundwater flow was calculated based on a 3-point solution for wells MW-6, 10 & 11. The historical calculations of gradients and directions are summarized in the following table: Table: Groundwater Gradient, 2004 & 2005 ' Date Gradient; Direction/Slope March 16, 2004 N370:E, 0.0047 ft/ft June 7, 2004 N480E, 0.0042 ft/ft 1 September 1; 2004 N600E, 0.0052 ft/ft December 2:3, 2004 N23°E, 0.0034 ft/ft March 17, 2005 N390E, 0.0047 ft/ft June 14. 2005 N7611E. 0.0111 ft/ft September 19; 2005 N47E, 0.0046 ft/ftDecember 14, 2005 N420E, 0.0039 ft/ft ' 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone (209) 569-4293 Modesto, CA 95356 Fax(209) 569-0293 I