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2 . 0 GROUNDWATER FLOW DIRECTION AND GRADIENT <br /> tOn December 23, 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 for the presence of <br /> free-floating hydrocarbons or sheen using an oil/water interface probe a n d <br /> a product thickness bailer No free-floating hydrocarbons were observed <br />' in any of the groundwater monitoring wells this quarter Groundwater <br /> elevation data is presented as Table One <br />' Groundwater elevation (potentiometric surface) contours are plotted on <br /> Figures 2, 3 and 4 Groundwater in the shallow zone (less than 20-feet <br />' bgs) has historically shown a northern or northwestern flow This quarter, <br /> the groundwater flow direction is primarily to the northwest with a <br /> gradient of approximately 0001-feet/foot A shallow zone potentiometric <br />' surface map is presented as Figure 2 <br /> Groundwater in the middle zone (55-70-feet bgs) flows toward the south <br />' this quarter at a gradient of approximately 00021-feet/foot <br /> The groundwater flow in the deep zone (greater than 100-feet) flows <br /> toward the east this quarter at a gradient of approximately 0 001 <br /> feet/foot <br /> IPotentiometric surface differences in wells adjacent to each other b u t <br /> screened in different zones such as monitoring wells MW-6, MW 7 a n d <br /> MW-8 show a decreasing hydraulic head with depth, suggesting the <br /> potential for downward groundwater flow <br /> I 3 . 0 GROUNDWATER SAMPLE COLLECTION <br /> On December 23, 2002, ASE collected groundwater samples from ten ( 10) <br /> of the on-site and off-site groundwater monitoring wells for analysis The <br /> number of wells to be sampled each quarter was proposed in ASE's letter <br /> I 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 /> IPrior to sampling, the site monitoring wells were purged of three well <br /> casing volumes of groundwater using a Grundfos pump and/or dedicated <br /> polyethylene bailers The pH, temperature, and conductivity of the purge <br /> water were monitored during evacuation, and samples were not collected <br /> Iuntil these parameters stabilized Samples were collected from the wells <br /> Frank's One Stop Quarterly Report — December 2002 Sampling <br /> r -2- <br />