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+l V A A S S O C I A T E S I N C in the water table elevation of approximately 2 14 feet since December 200; The water level data were used to develop the groundwater elevation contour map (Figure Assuming that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the site flowed towards the southeast The average hydraulic gradient on March 3, 2003 was calculated to be 0 002 ft/ft or approximately 8 3 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 40 gallons of free product has been recovered from the skimmer in well MW2 since Installation On January 24, March 3, and March 27, 2003 an unmeasurable sheen was observed in well MW2 Table 3 summarizes the product thickness measurements and volume of product removed through the end of the first 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 Influent water samples collected from DW on March 3, 2003 contained 12,000 ppb of TPHg and 1,100 ppb of benzene Fuel oxygenates Including MTBE were not detected in water samples collected from well DW TPHg and fuel oxygenates were not detected in water samples from the first and second effluent ports Identified as 1 CC Effluent and 2CC Effluent in the filtration system on January 24, March 3, or March 27, 2003 On January 24, 2003 and March 3, 2003 benzene was detected In the 1 CC Effluent sample at 2 ug/L On March 27, 2003 benzene was detected in the 2CC Effluent sample at 0 9 ug/L As soon as data was available, ATC resampled 2CC Effluent in April 2003 and analytical results Indicated petroleum hydrocarbons were not present April sampling will be summarized in the Second Quarter 2003 report It appears the filtration system is effective in removing petroleum products from water from well DW Analytical results are summarized in Table 2 CONCLUSIONS Concentrations from wells MW1 through MW10 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 Increased since December 2002 S 1Enviromental1163431REPORTS11gr-2003 doe 4