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1 <br /> FIRST QUARTER, 1997 <br /> GROUNDWATER MONITORING REPORT . <br /> FORMER DIAMOND LUMBER - MANTECA ' <br /> APRIL, 1997 <br /> 2.2 Monitoring Well Purging ' <br /> Each sampled well was purged using a submersible pump until at least three equivalent well <br /> volumes of water had been removed and pH, temperature and conductivity measurements had <br /> stabilized All purging and sampling equipment was washed in a trisodium phosphate solution and <br /> rinsed to distilled water prior to each usage to reduce the potential for cross contamination <br /> between wells The pH, temperature and conductivity measurements were recorded on field data ' <br /> sheets, which are kept in a permanent project file The wells were allowed to stand for a period of <br /> time to equilibrate prior to sampling Groundwater purged from the wells was placed into DOT <br /> approved 55-gallon drums The purge water will be disposed of by pumping into a vacuum truck ' <br /> and sending it to a recycling facility <br /> 2.3 Groundwater Sampling ' <br /> Proper sample collection and handling are essential to assure quality data obtained from a sample <br /> Each groundwater sample, therefore, was collected using a new disposable bailer for each well ' <br /> and placed in the appropriate labotatory prepared containers, using proper protocol The samples <br /> were labeled with the date, time, identifying well number, placed into a cooler at 4° C, and 1 <br /> transported to the laboratory under continuous chain-of-custody (COC) documentation The <br /> laboratory teports and COC documentation ate included in Appendix B <br /> 2.4 Groundwater Analyses ' <br /> Analyses of the sampled groundwater was performed by Sierra Laboratories, Inc (Sierra), a <br /> California certified laboratory Samples were analyzed in accordance with state guidelines and <br /> EPA protocols <br /> 3.0 SUMMARY AND CONCLUSIONS <br /> 3.1 Results of Groundwater Laboratory Analyses <br /> TPH G was reported in four of the eight sampled wells TPH G was reported at concentrations <br /> ranging from non-detect in SRK-MWI, SRK-MW3, MW-7-P, and MW-8-P to 22,000 <br /> micrograms per liter (µg/1) in BEI-MW3 Benzene was reported in all wells sampled this quarter <br /> at concentrations ranging from 10 µg/1 in SRK-MW3 to 2,500µg/1 in BET-MW3 Both off-site ' <br /> wells were non-detect (ND)) for TPH, and low to ND for BTEX constituents The laboratory <br /> results far this sampling event are presented on Figure 3, and in Table 2 ' <br /> 4 <br /> I 1 <br /> 2 <br />