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THIRD QUARTER,1997 <br /> GROUNDWATER MONITORING REPORT <br /> USA STATION##65-LODI <br /> AUGUST,1997 <br /> During the groundwater purging operations, physical parameters such as pH, temperature and <br /> conductivity were monitored and recorded on field data sheets. Groundwater purging was <br /> discontinued when 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 /> using 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 <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 v <br /> conducted on July 10, 1997. <br /> 5.1 Groundwater Flow and Gradient <br /> Groundwater data collected at the site on July 10, 1997 indicate that the depths to groundwater <br /> ranged from 40.62 to 42.83-feet bgs. The groundwater elevations ranged from 3.58 to 4.95-feet -- <br /> below MSL. Groundwater elevations have lowered since the second quarter monitoring event. <br /> The direction of groundwater flow has been calculated to the south southeast with an average -' <br /> hydraulic gradient of approximately 0.003-ft/ft across the site. Historic field data suggests that <br /> the groundwater generally flows southerly, with minor fluctuations to the east and/or west, as <br /> shown on Figures 3 and 4. <br /> 5.2 Results of Groundwater Laboratory Analyses <br /> The July 10, 1997 analytical results reported TPH G in five of the ten monitoring wells sampled <br /> (MW-2, MW-3, MW-8, S-1, and S-2). <br /> 4 <br />