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Mr Jeff Wong Page 5 of 5 December 31, 2003, with a period of non-operation from November 18 through December 11 The average flow rate during the reporting period was 14 gpm Approximately 62,250 gallons of water were treated between November 5 and December 30, 2003 Additional subsurface investigation was conducted during the reporting period The additional work included the installation of three shallow groundwater monitoring wells, one B Zone well, one C Zone well, and a vapor extraction test well The additional groundwater monitoring wells were developed and sampled, and a vapor extraction test was conducted to investigate the feasibility of using vapor extraction technology to remove petroleum hydrocarbons from the subsurface The results of the additional investigation were submitted in a summary report dated May 20, 2004 ' Groundwater in the shallow aquifer beneath the site generally flowed to the northeast when monitored on December 10, 2003, although a pumping depression was evident around the extraction well (MW 1) ' MTBE was detected at elevated levels (2,000-2,500 ppb) in downgradient A Zone well MW12 and at relatively low levels in C Zone well MW 13C, which is located east of the former water supply well No ' MTBE was detected in B Zone well MW 14B, which is located within a few feet of the former water supply well ' 7 0 RECOMMENDATIONS Based upon the data summarized herein, Ground Zero recommends installing two additional shallow monitoring wells to further investigate the extent of MTBE downgradient (north and northeast) of well MW12 Please contact Ground Zero at (209) 838-9888 if you have any questions or require additional information ' Respectfully, r Ground Zero Analysis, Inc RED GFO` ' � O JOHN P John P Lane 67 ' Registered Geologist 6795 No 6T95 CA Re g g Attachments 4F C�l) ' 1 cc Mr Ray Baghetto/Mr Frank Rauzi ' Mr James L L Barton, CRWQCB G 1GROUNDZEITULEBURG1Rcports%QMR1200314QM2003 dm