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I <br /> Second Quarter 2001 Monitoring and Sampling Report 2 <br /> 7-Eleven,Inc Store No 20632,4627 Da%Anci Drive,Stockton,CA July S, 2001 <br />' Monitoring Well Sampling and Analytical Results <br /> Quarterly groundwater samples were collected after purging at least 4 well-casing volumes of groundwater <br />' from each monitoring well, unless the well was purged dry The groundwater samples were collected using <br /> disposable bailers Groundwater samples were placed in analysis-specific containers with analysis-specific <br /> preservative The samples were then sealed using Teflon septum caps, labeled with the job identification <br /> number, the sample number, date,bme, and type of laboratory analysis required The samples were <br /> stored on Ice and transported with a chain-of-custody record to a state-certified laboratory for analysis <br /> Groundwater samples were analyzed for BTEX and TPH-G using Environmental Protection Agency(EPA) <br /> methods 8021 B/modified 8015, and for oxygenates MTBE,TBA, DIPE, ETRE, and TAME using EPA <br /> method 8260B <br /> Analytical results for the quarterly sampling event are presented in Table 1, and historical laboratory <br /> analytical results are summarized in Table 2 Highest dissolved benzene concentrations were reported in <br /> well MWA at 14 micrograms per liter(pg/L) Dissolved MTBE was found in wells MW-1 (2 5 Ng/L),MW-2 <br /> (2,100 pg/L) and MW-5 (86 pg/L), no detectable MTBE was found in well MW-3 Selected dissolved <br /> constituents are plotted on Figure 2 The laboratory analytical reports are included in Attachment 4 <br /> Pnor to purging,dissolved oxygen (DO) levels were recorded in each well Dissolved oxygen levels indicate <br /> anearobic conddions (0 7-2 0 milligrams per liter(mg/L)) (Table 1) <br /> As mentioned in previous quarterly reports, a well search database for public water supply wells located <br /> within one mile of the site indicates that there are no public water supply wells located within 1 mile <br /> downgradient from the site <br /> Purgewater Disposal <br /> All purgewater generated during this quarterly monitoring and sampling event was stored in 55-gallon <br /> Department of Transportation (DOT)-approved drums, pending proper transport and disposal Waste <br /> disposal documentation will be forwarded once received <br /> i <br /> t <br /> 1 <br /> 20632012 QMR <br />