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1 <br /> FOURTH QUARTER,1997 ' <br /> GROUNDWATER MONITORING REPORT . <br /> USA STATION 965-LODI <br /> NOVEMBER,1997 ' <br /> 4.2 Monitoring Well Purging <br /> The monitoring wells were purged using a 2-inch diameter submersible Grundfos groundwater <br /> pump or disposable bailer, until a minimum of three equivalent well volumes of water were <br /> removed from each well Groundwater purged from the wells was placed into Department of , <br /> Transportation (DOT) approved 55-gallon drums and stored on-site prior to disposal by USA <br /> To reduce the potential for cross-contamination betweenwells,_all purging and sampling ' <br /> equipment was washed in a trisodium phosphate solution and rinsed in potable water prior to each <br /> use <br /> During the groundwater purging operations, physical parameters such as pH and conductivity <br /> were monitored and recorded on field data sheets Groundwater purging was discontinued when <br /> the physical parameters indicated above stabilized in the purged groundwater <br /> 4.3 Groundwater Sampling ' <br /> Prior to sampling, the wells were allowed to recharge to a minimum of 80 percent of their initial <br /> static water levels Groundwater samples were then collected from each well using a new <br /> disposable bailer The samples were placed into the appropriate laboratory prepared containers, <br /> rising proper sample handling and chain-of-custody(COC) protocol established under applicable <br /> SW-846 procedures issued by the USEPA The samples were labeled with the date, time, <br /> identifying well number, stored in a cooler at 4° Centigrade or less, and transported to a state <br /> certified laboratory under completed COC documentation <br /> 4.4 Groundwater Analyses ' <br /> Groundwater samples were analyzed for TPH G, BTEX and MTBE using EPA Methods 8015 i <br /> Modified and 8020, respectively The analyses were conducted by Sierra Laboratories, Inc <br /> (Sierra), a California State certified laboratory in accordance with state guidelines and EPA <br /> protocol ' <br /> 5.0 SUMMARY AND CONCLUSIONS <br /> The following sections discuss findings from the groundwater gauging and sampling activities <br /> conducted on October 6, 1997 <br /> 4 <br />