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' 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 pursed using a submersible pump until at least three equivalent well <br /> P P .. g <br /> volumes of water had been removed and pH, temperature and conductivity measurements had <br /> ' stabilized All purgmg and sampling equipment was washed in a tnsodxum phosphate solution and <br /> rinsed in 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 penod of <br /> tune 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 track <br /> and sending it to a recycling facility <br /> 2.3 Groundwater Sampling <br /> 1 <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 laboratory prepared containers, using proper pl otocol The samples <br /> were labeled with the date, time, identifying well number,placed into a cooler at 4° C, and <br /> tiansported to the laboratory under continuous chain-of-custody (COC) documentation The <br /> laboratory reports and COC documentation are included in Appendix B <br /> 2 4 Groundwater Analyses <br /> f 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 /> 30 SUMMARY AND CONCLUSIONS <br /> ' 31 Results of Groundwater Laboratory Analyses <br /> TPH G was repo,ted n four of the eight sampled xlclls TPH G ,�as ,-:,ported at concentrations <br /> nanQinQ from non-detect in SRK-MWI, SRK-MW3, MW-7-P, and MW-8-P to 22,000 <br /> rrucrogiams per Mer (µg/1) in BEI-MW3 Benzene was reported in all wells sampled this quarter <br /> at concenttatnons ranging from 1 0 µgel in SRK-MW3 to 2,500 µg1l in BEI-MW3 Both off-site <br /> wells were non-detect (ND) for TPH, and low to ND for BTEX constituents The laboratory <br /> . iesults for this sampling event are presented on Figure 3, and in Table 2 <br />