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2 . 0 GROUNDWATER FLOW DIRECTION AND GRADIENT <br /> On February 25, 2002, ASE measured the depth to water in each site <br /> groundwater monitoring well using an electric water level sounder The <br /> surface of the groundwater was also checked foi the presence of <br /> flee-floating hydrocarbons or sheen using an oil/water interface probe a n d <br /> a product thickness bailer Free-floating hydiocarbons were not observed <br /> in any of the groundwatei monitoring wells measured Groundwater <br /> elevation data is presented a5 Table One <br /> Gioundwater elevation (potentiometzic surface) contours are plotted on <br /> Figuie5 2, 3 and 4 Gioundwatei in the shallow zone (less than 20-feet <br /> bgs) has historically shown a northein flow This quarter, the groundwatei <br /> flow direction is primarily to the northwest with a gradient of <br /> approximately 0 00078-feet/foot A shallow zone potentiometiic surface <br /> map is presented as Figure 2 <br /> Gi oundwatet in the middle zone (55-70-feet bgs) flows towaid t h e <br /> southwest this quarter at a gradient of approximately 0 0014-feet/foot <br /> • The gioundwatei flow in the deep zone (gieatei than 100-feel) flows <br /> toward the southwest this quarter at a gradient of appioxrmately 0 00042 <br /> feet/toot <br /> Potentiometrrc surface di#ferences in wells adjacent to each othei b u t <br /> scieened in different zones such as monitoring wells MW-6, MW 7 and <br /> MW-8 show a decreasing hydraulic head with depth, suggesting the <br /> potential for downward groundwater flow <br /> 3 . 0 GROUNDWATER SAMPLE COLLECTION <br /> On February 26 and 27, 2002, ASE collected gioundwater samples fi om <br /> fifteen (15) of the site groundwater monitoring wells for analysis The <br /> number of wells to be sampled each quattei was pioposcd in ASE's lettei <br /> to the San Joaquin County PHS-EHD dated September 2, 2001 and <br /> approved during a subsequent telephone conversation with Lori Duncan of <br /> the PHS-EHD <br /> Prior to sampling, the site monitoring wells were purged of fout well <br /> casing volumes of gioundwatei using a Giundfos pump and/or dedicated <br /> polyethylene bailers The pH, temperature and conductivity of the pui ge <br /> • water was monitored during evacuation, and samples were not collected <br /> until these parameters stabilized Samples were collected from the wells <br /> Frank's One Stop Quarterly Report — February 2002 Sampling <br /> -2- <br />