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and pH and recorded on well data sheets. The groundwater monitoring wells, surface iwater monitoring points, and leachate were sampled in accordance with the sampling and analysis procedures detailed in Appendix B. The well data sheets, raw laboratory data, certificates of analyses, and chain-of-custody records related to the sampling program are included in Appendix C. The results of both field and laboratory analyses are summarized in Tables 3-1 through 3-6. 3.1.2 QA/QC Results The QA/QC program completed for the fourth quarter 2007 water quality monitoring event at the Austin Unit included analyses of three field blanks, three trip blanks, three laboratory method blanks, and one duplicate sample. The trip, field, and laboratory method blanks were analyzed for VOCs by EPA Method 8260 and are included with the laboratory data in Appendix C. The results of the QA/QC program indicate that trace levels of chloroform was detected in one of the QA/QC field blanks during the fourth quarter 2007 monitoring event. Review of the primary sample results indicates that a similar concentration of chloroform was detected in the primary sample collected from well AMW-19BR, and therefore, was flagged as a suspected field/laboratory contaminant. A duplicate sample was collected from well AMW-10 and labeled AMW-DUP. Duplicate groundwater results are presented along with the primary data in Table 3-1. Comparison of the quantified values(values above the PQL) in the primary sample with the duplicate indicates that with the exception of TCE, there was good agreement (within 5%). Review of laboratory analysis dates with required holding times indicates that all samples were submitted and analyzed within the required holding times during the fourth quarter 2007. Based on the results of the laboratory blank and duplicate analyses, it is concluded that the laboratory data generated for the fourth quarter 2007 monitoring period are generally acceptable. 3.1.3 Groundwater Elevations and Contours Prior to purging and sampling, each well was sounded for water depth using a weighted electronic sounder, and the static water level was recorded on a well data sheet (Appendix Q. The groundwater elevations were calculated for each well by subtracting the depth-to-water measurement from the top-of-casing reference elevation. The current groundwater elevation data for the Austin Unit are summarized in Table 3-5. The groundwater elevation data obtained during this quarterly monitoring period were used to generate the groundwater elevation contour map shown on Figure 3-1. Historically, groundwater beneath the Austin Unit generally flows to the north-northwest at an average hydraulic gradient of approximately 0.002 ft/ft. However, based on lower groundwater levels associated with observed pumping from adjacent agricultural wells, groundwater during the fourth quarter 2007 monitoring period appears to flow west- southwest to northwest at a gradient of 0.002 ft/ft. D:\2007_0043\Fo—ard Austin 4Q07.doe 9 Geologic Associates