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Mr. James Barton ' October 31,2002 Page 4 of 5 '• GROUNDWATER MONITORING ' On September 25, 2002, SECOR sounded five groundwater monitoring wells (MW-1 through MW-5) using an electronic water-level indicator graduated to 0.01 feet. The depth-to-groundwater was measured in each well and recorded on the water sample data field sheets included in Appendix A. The water-level indicator was rinsed with deionized water between the sounding of each well to minimize the potential for cross contamination. In accordance with the revised MRP, the sampling plan for the Third Quarter 2002 as shown on the table ' below. QI Q2 Q3 Q4 ' MW-1 NS NS NS NS MW-2 NS NS TPH PHd NS MW-3* TPHWTPHd TPH Hd TPH PHd TPHgtTPHd MW-4 TPH PHd TPH PHd TPH PHd TPHg1TPHd MW-5 NS NS NS NS * Sample well MW-3 only if no free-product is present. NS-Not Sampled Prior to sampling, wells were purged of approximately three casing volumes of water using a dedicated disposable PVC bailer. During purging, pH, electrical conductivity, and temperature of the evacuated groundwater were measured, and the groundwater was visually observed for color, turbidity, and the ' presence of floating chemical product. Physical parameters were recorded on water sample field data sheets included in Appendix A. Upon removal of the appropriate purge volume, stabilization of the measured parameters, and allowing ' water level recovery to 80 percent of the static level; samples were collected from each well using a dedicated disposable PVC bailer. Groundwater samples were decanted into prelabeled laboratory- supplied glassware, placed in an ice-filled cooler, and transported under chain-of-custody documentation ' to STL San Francisco of Pleasanton, California, a state-certified analytical laboratory. Third Quarter 2002 groundwater samples were analyzed for TPHg and TPHd by modified EPA Method 8015. Laboratory analytical reports and chain-of-custody records are included in Appendix B. ' Results of quarterly groundwater monitoring activities for the Third Quarter 2002 are summarized with historical results in Table 1. ' Groundwater Elevations ' A groundwater elevation contour map based on the Third Quarter 2002 groundwater elevation data is presented as Figure 3. During the September 25, 2002 monitoring event, groundwater elevations ranged from -13.04 to 2.09 feet relative to mean sea level (msl). The maximum groundwater elevation change between the Second and Third Quarter 2002 monitoring events was an increase of 3.24 feet in well MW- ' 5. Historical groundwater sounding data is summarized in Table 2. Interpretation of the groundwater elevation contour map created from the Third Quarter 2002 sounding data indicates groundwater flow is directed away from Potato Slough towards the southeast under an I:\Tower Park\QMR\2002 QMR\Q3-2002\3rd QTR 2002.doc SECOR International Inc. SECOR lob No.050T.02926 11/1/02 1:56 PM