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v , o A S S O C I A T E S I N C average hydraulic gradient on September 9, 2003 was calculated to be 0 002 Rift or approximately 115 ft/mile A summary of groundwater monitoring data is presented in Table 1 FREE PRODUCT REMOVAL Floating petroleum product has previously been observed in well MW2 On January 18, 2002, ATC installed a passive skimmer system in well MW2 in accordance with ATC's Workplan for Drinking Water Well Replacement, Temporary Water Source, and Free Product Skimmer Installation at Pacific Coast Recreation, 3755 Munford Avenue, Stockton, California, dated October 11, 2001 This workplan was approved by SJCEHD with minor modifications A total of approximately 0 43 gallons of free product has been recovered from the skimmer in well MW2 since installation On July 11, August 1, and September 9, 2003 an immeasurable sheen was observed in well MW2 Table 3 summarizes the product thickness measurements and volume of product removed through the end of the third quarter of 2003 _ FILTRATION SYSTEM In May 2002, a carbon filtration system was installed to remove petroleum hydrocarbons from . the water in domestic well DW On July 11, August 1 and September 9, 2003, water samples were collected from the first and second effluent ports identified as ICC Effluent and 2CC Effluent in the filtration systen;,.9 On July 11, and August 1, 2003, benzene was detected in the 1C Effluent samples at 18 and 3Tppb ppb, respectively On September 9, 2003, TPHg, benzene, and toluene were detected from the 1 CC Effluent sample at 320, 94, and 0 7 ppb, respectively All other constituents were reported as not detected On September 9, 2003, influent water samples collected from DW contained 49,000 ppb of TPHg and 2,200 ppb of benzene MTBE and fuel oxygenates were not detected, nor have they been detected in water samples collected from well DW for the past 12 consecutive quarters The first carbon vessel is scheduled to be replaced with fresh carbon during the first month of the fourth quarter 2003 It appears the filtration system is effective in removing petroleum products from groundwater extracted by well DW Analytical results are summarized in Table 2 CONCLUSIONS - Concentrations from wells MW1 through MW10 and DW remain consistent with the results from the previous sampling event The direction of groundwater flow was consistent with the previous monitoring event Groundwater elevations have decreased since June 2003 S\Enviromentah163931REPORTS13gr-2003 doc 4