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• ASS OCIATES INC GROUNDWATER FLOW DIRECTION Water level measurements were collected from wells MW1 through MW10 on March 25, 2004 Water levels in the shallow aquifer ranged from 66 13 to 67 84 feet below the tops of the well casing elevations, representing an average increase in the shallow water table elevation of approximately 2 63 feet since December 2003 The water level data were used to develop the groundwater elevation contour map (Figure Assuming that horizontal isotropic conditions J prevail, groundwater in the uppermost aquifer beneath the site flowed generally towards the l� 1 north-northwest The average hydraulic gradient on March 25, 2004 was calculated to be 0 002 ft/ft or approximately 11 5 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 the San Joaquin County Environmental Health Department (SJEHD) with minor modifications The passive bailer was removed from MW2 on December 3, 2003 because it was no longer needed A total of approximately 0 43 gallons of free product has been recovered from the skimmer in well MW2 since installation On March 25, 2004 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 fourth 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 January 9, 2004 and March 26, 2004, water samples were collected from the first and second effluent ports identified as ICC Effluent and 2CC Effluent in the filtration system During both sampling events, all constituents from 1 CC Effluent and 2CC Effluent were reported as not detected It appears the filtration system is effective in removing petroleum products from groundwater extracted by well DW Analytical results are summarized in Table 2 ADDITIONAL ACTIVITIES On July 21, 2003, approximately 2,800 gallons of water was removed from DW during a pump test and stored in a tank on-site Approximately 1,500 gallons of the stored water was pumped 40 through the on-site activated carbon filtration system and surface discharged on January 16, S\EnviromentaRl63931REPORTS1lgr-2004 doc 4