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Groundwater Investig31k and Groundwater Extraction Work Plan Boyett Petroleum,419 S.Main Street,Manteca May 16,2006 Page 4 V Condor proposes to conduct batch groundwater extraction at monitoring well MW-11 to reduce the concentration of MTBE in groundwater in the vicinity of the well. A submersible pump will be installed in MW-11. The discharge from the pump will be connected to three 200-pound carbon canisters y connected in series. Treated water will be discharged from the carbon canisters to the sanitary sewer. Condor will obtain an Industrial Wastewater Discharge Permit(IWDP) from the PWD prior to installation of the pump and equipment. A temporary fence will be placed around the pump and carbon canisters for `r security purposes. Groundwater will be extracted from MW-11 for seven days. Water samples will be collected from the �+ pump discharge and from the discharge of the carbon canisters at the beginning and the end of the seven day pumping period. The water samples will be analyzed for gasoline oxygenates/additives (MTBE, ethanol, TBA, DIPE, ETBE, TAME, 1,2-DCA, and EDB). Two weeks after the extraction is completed, groundwater samples will be collected from the deeper wells(MW-9, MW-11, and EW-1)as these are the only wells in which MTBE was detected during the first quarter 2006 groundwater monitoring event. If the concentration of MTBE in a groundwater sample collected from any of the wells exceeds the California Department of Health Services Primary Maximum Contaminant Level (MCL) of 13 V micrograms per liter (gg/L), then another seven days of batch groundwater extraction will be conducted following the same procedures. Batch groundwater extraction will continue until the concentration of MTBE in groundwater at the site is below the MCL. V 5.0 RISK ASSESSMENT Condor will evaluate the risk of soil vapor intrusion to all nearby structures using the data obtained from the groundwater investigation described in this work plan and the data from the most recent groundwater monitoring event. The residual contaminant concentrations proposed to be left in place will be compared with the California Human Health Screening Levels (CHHSLs) and Environmental Screening Levels `r (ESLs) published by the San Francisco Bay Regional Water Quality Control Board in their technical document Screening for Environmental Concerns at Sites With Contaminated Soil and Groundwater. Condor will provide a fate-and-transport model showing the path of travel of the plume before it reaches L' background levels and an estimate of the time required for background levels to be achieved. 6.0 REPORTING V Condor will prepare a report that presents the results of the groundwater investigation,the risk evaluation, and the fate-and-transport modeling to be submitted to the SJCEHD and the CRWQCB. Condor will prepare individual reports to present the results of each batch groundwater extraction event to be submitted to the SJCEHD and the CRWQCB. Condor will also submit the reports in electronic format to GeoTracker. 6W 7.0 PROJECT SCHEDULE Upon approval of this work plan by the SJCEHD and notification from Boyett Petroleum to proceed,the field portion of the groundwater investigation can be completed within approximately eight weeks. A report that describes the results of the groundwater investigation, the risk evaluation, and the fate-and- transport modeling can be submitted to the SJCEHD and CRWQCB within eight weeks of completion of the fieldwork. v V V 4M CONDOR V