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"Certified clean" one liter glass sample containers, supplied by the laboratory, were used <br />' during the collection of groundwater samples Samples were analyzed in accordance with <br /> EPA Method 8015 Modified The samples were placed on ice immediately following <br /> collection, and kept in coolers until delivery to laboratory <br /> 4.0 Results and Discussion <br /> This section presents a discussion of the soil and groundwater investigation conducted at <br /> the Site during the Fall/Winter 1998 This section also includes a discussion of historical <br /> groundwater data collected at the Site This report does not include a detailed discussion of <br /> TPH-D soil data, which was previously assessed in the report entitled "Evaluation of <br /> Hydrocarbon Mobility" (Dames & Moore, 1995a) <br /> The laboratory reports provided by Quanterra was reviewed by Dames & Moore's internal <br /> data validation group in order to insure that the data results are accurate Results of the <br /> Dames & Moore QA/QC are included in Appendix D All data was determined to be <br /> acceptable for use <br /> 4.1 Groundwater Levels <br /> Groundwater levels have been measured during 15 separate events conducted between July <br /> 1987 and January 1999 Water level data are compiled in Table 2 The groundwater <br /> contour map for January 1999 is shown on Figure 3, which also indicates the previous <br /> groundwater flow directions Historical groundwater elevation contour maps are attached <br /> in Appendix F <br /> Table 2 presents groundwater levels between 1987 and 1999 Between July 1987 and July <br />' 1991, the groundwater level declined approximately 41 feet, reaching a maximum depth of <br /> approximately 61 feet bgs Between 1991 and 1999, water levels continued to rebound <br /> The current depth to groundwater is approximately 38 feet bgs, indicating that the <br /> groundwater level has risen approximately 31 feet since 1991 Current water levels are <br /> approximately 12 feet below the levels reported in 1987 <br /> 1 <br /> Between 1987 and 1989, the direction of groundwater flow appears to have shifted from <br />' northwest to a northeastern direction, as indicated in Figure 3 However, it should be noted <br /> that the measured gradients are flat (0 0008 ft/ft) Maximum water level variations within <br />' the Site are in the range of 2 inches <br /> DAMES&MOORE 5 Rlsac1044mtsc19902,03 doc <br />