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2 Second Quarter 2000 Monitoring and Sampling Report Ma g 2000 7-Eleven Inc Store#21756 853 E Yosemite Avenue Manteca CA ' Monitoring Well Sampling and Analytical Results On April 7, 2000, groundwater samples were collected from the three monitoring wells Dissolved oxygen t (DO) concentrations were measured in the three wells prior to sampling The groundwater samples were collected using disposable bailers Groundwater samples were placed in analysis-specific containers with analysis-specific preservative The samples were then sealed using Teflon septum caps, labeled with the fob identification number, the sample number, date, time, and type of laboratory analysis required The samples were stored on Ice and transported with a chain-of-custody record to a state-certified laboratory Groundwater samples were analyzed for BTEX, MTBE, and TPH-G using EPA methods 8021/modified 8015 and for the oxygenates MTBE, TBA, DIPE, ETRE, and TAME using EPA method 8260 ' Dissolved oxygen readings ranged from 0 9 mg/L in MW-1 to 2 3 mg/L in MW-3 (Table 1) Laboratory analytical results for groundwater samples collected on April 7, 2000 and historical results are ' summarized in Table 1 Dissolved benzene concentrations were not detected above reporting limits in any of the wells sampled The highest dissolved TPH-G and MTBE concentrations were detected in downgradient well, MW-1 at 180 pg/L and 1,900 pg/L, respectively The other oxygenates were not ' reported above detection limits in any of the wells sampled during the second quarter 2000 The laboratory analytical reports for the groundwater samples are included in Attachment 4 Well Search IT Corporation performed a well search using multiple sources of information to assemble a database for public water supply wells located within one mile of the site The database includes well ownership,depth of sanitary seal, well type, length of screen, location, operating pumping rate, status, and any available ' testing information The database for this site (Attachment 5) indicates there are 19 public water supply wells within a one mile radius of the site The nearest well is an active municipal well located 1,987 feet downgradient of the site, it is 155 feet deep, with top of screen at approximately 65 feet below grade ' Purge Water Transportation and Disposal ' Approximately 41 gallons of purge water generated during this quarterly monitor ing and sampling event was stored in 55-gallon Department of Transportation (DOT)-approved drum pending characterization and ' proper disposal by a licensed waste hauling company 21756g2 rpt