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V ` A S S O C I A T E S I N C The average hydraulic gradient on December 3, 2003 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 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 December 1, 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 fourth quarter of 2003 On December 3, 2003 the passive bailer was removed from MW2 because it is no longer needed FILTRATION SYSTEM • In May 2002, a carbon filtration system was installed to remove petroleum hydrocarbons from the water in domestic well DW On October 15 and December 1, 2003, water samples were collected from the first and second effluent ports identified as ICC Effluent and 2CC Effluent in the filtration system On October 15, 2003, benzene was detected in the 1 CC Effluent sample at 610 ppb The first carbon vessel (ICC) was replaced with fresh carbon on October 24, 2003 The carbon vessel order was rearranged so that the fresh carbon is now the second carbon vessel On December 1, 2003, all constituents from 1CC 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 Approximately 1,000-gallons of water was pumped through the on-site activated carbon filtration system and surfaced discharged on October 24, 2003 A water sample of the discharged water was collected and contained no detectable concentrations of petroleum hydrocarbons The discharge was done under the supervision of the PHS/EHD and at a rate slow enough to ensure no runoff to the storm drainage system occurs A complete report of the pump test is discussed in the Summary Report of Additional Subsurface Investigation to be issued separately S\Fnviromenta11163931REPORTS14gr-2003 doc 4