SITE INFORMATION AND CORRESPONDENCE

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S ECOR --- Mr.James Barton January 22, 2003 Page 5 Groundwater Elevations ■ A groundwater elevation contour map based on the Fourth Quarter 2002 groundwater elevation data is presented as Figure 3. During the December 17, 2002 monitoring event, groundwater elevations ranged from -11.69 to 2.06 feet relative to mean sea level (msl). The maximum groundwater ■ elevation change between the Third and Fourth Quarter 2002 monitoring events was a decrease of 2.93 feet in well MW-5. Historical groundwater sounding data is summarized in Table 2. ■ Interpretation of the groundwater elevation contour map created from the Fourth Quarter 2002 sounding data indicates groundwater flow is directed away from Potato Slough towards the southeast under an average hydraulic gradient of approximately 0.07 feet per foot (ft/ft). This groundwater flow pattern is consistent with historical monitoring data as shown in Table 3. ■ Free-Product Monitoring and Removal from Well MW-3 ■ Marina personnel continued to monitor the condition of the hydrophobic, hydrocarbon-absorbent sock in well MW-3 on an approximate bi-weekly basis to assess the need for sock replacement. According to marina personnel the sock was not replaced during the Fourth Quarter 2002 and no free-product was observed floating on the groundwater surface during the December 17, 2002, monitoring event. Fourth Quarter 2002 Analytical Results Fr Groundwater analytical results for the Fourth Quarter 2002 are summarized on Table 1 and displayed graphically on Figure 4. TPHd was detected in wells MW-3 and MW-4 at respective concentrations of 380 and 270 micrograms per liter(pg/L). TPHg was reported at a concentration of ■ 91 pg/L in the sample from well MW-3, and was not detected above the reporting limit of 50 pg/L in well MW-4. 0 Comparison to Historical Analytical Results The concentration of TPHd reported in well MW-3 remained unchanged since the September 2002 sampling event, and the concentration of TPHd reported in well MW-4 increased slightly since ■ September 2002. Similarly, the concentration of TPHg remained unchanged in well MW4, and increased slightly in well MW-3. RECOMMENDATION FOR REGULATORY CLOSURE SECOR believes the site has reached the criteria for regulatory closure based on the following: ❑ Free product has not been observed in well MW-3 during quarterly groundwater monitoring in 2002; ❑ Concentrations of TPHg and TPHd in wells MW-3 and MW-4 are stable; and I:\Tower Park\QMR\2002 QMR\Q42002\4th QTR 2002.doc SECOR International Incorporated SECOR Project No.0507.02926.0_0.0004 1/22/2003 4:30 PM