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fiom well MW10 is most likely pulling the MtBE plume from CCFF onto the Sanchez . property, thus removing MtBE from both sites while pumping is occurring FIGURE 7B Figure 7B represents the MtBE plume in the B zone Figure 7B resembles figure 7A with the only difference being an increase in MtBE found at well 6B Historic water samples obtained from piezometers PZIB and PZ2B contained 78 and 21 ug/L respectively TBA FIGURE 8A Figure 8A represents the TBA plume in the A zone TBA is only evident in well MWBA at 6 1 ug/L Historically TBA was detected in "GeoProbe" holes P8 and P10 at 11 and 6 ug/L respectively (February 2001) Figure 9 illustrates the subsurface hthology and the extent of the A and B zones groundwater plumes within the A and B zones . SUMMARY AND RECOMMENDATIONS The City of Stockton Department of Municipal Utilities in a letter addressed to Mary Sanchez, dated October 8 2004 gave notice of intent to hold Mary Sanchez liable for costs of mitigating contamination that is encountered during the construction of a trunk sewer line along Country Club Blvd San Joaquin County Health approved a workplan submitted by Western Geo-Engineers to install a pump into well MW10 The City of Stockton Municipal Utilities Department has granted a permit to discharge treated pumped water from well MW 10 to the sanitary sewer at a rate not to exceed 10 gallons per minute Groundwater pumping from MW10 commenced on April 8, 2005 with discharge to sewer (7 gpm) occurring at that time The City of Stockton construction of the sewer line came near the site on April 27, 2005 The groundwater pump and treatment system was turned off on May 10, 2005 due to the presence of TBA (7 1 ug/L) in the discharge to sewer A request to modify the treatment system was drafted and submitted to the City of Stockton Department of Municipal Utilities on May 23, 2005 Completion of the treatment system modification was completed on August 25, 2005 and the system was tested on that date, pumping 751 gallons from MW10 through the treatment system into a 22,000 gallon capacity Baker Tank, with no discharge to sewer The pump and treatment system was restarted on September 1, 2005 The Baker Tank, high level float switch was activated after 16,911 gallons of groundwater had been pumped from MW10 and treated through the carbon/aeration system Samples of this treated and stored water showed that this water met sewer discharge requirements and was discharged to the sanitary sewer on September 21 through 23, 2005 at a rate of 5 gpm To determine the influence that pumping from MW10 was having on surrounding 11 Sanchez QM 4t1' 2005