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FIGURE 813 • Figure 813 represents the TBA plume in the B zone TBA was previously evident in wells MW613 and 8B at 10 and 7 7 ug/L respectively, currently TBA is below laboratory lower detection limts of 5 ug/L Figure 9 illustrates the subsurface lithology 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 MW10 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 carbon units were subjected to high pressure (greater than 12 psi) and the system was shut down to determine the cause of the high pressure It was felt that the restriction from the water totalizer may have caused the high pressure, the system was restarted without the totalizer in the the system, but the high pressure persisted It was discovered that the discharge line from the last carbon unit (carbon ##5) was partially clogged, restricting the flow to the Baker Tank The clog was removed and the pump and treatment system 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 wells, depth to water measurements were obtained prior to pumping, prior to termination of pumping and five days after termination of pumping at a rate of 8 9 gpm from September 28 through October 5, 2005 16,623 gallons were pumped from MW10, treated through the carbon/aeration system and stored in the Baker Tank during that time Charts developed from the depth to water measurements show that pumping from MW10 at a rate of 8 9 gpm influences the Country Club Food and Fuel wells A second pump influence test is scheduled for October 2005 at a rate of 5 gpm 11 Sanchez QM 3`d 2005