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2 .0 GROUNDWATER FLOW DIRECTION AND GRADIENT <br /> On September 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 for the presence of <br /> free-floating hydrocarbons or sheen using an oil/water interface probe and <br /> a product thickness bailer Free-floating hydrocarbons were observed in <br /> groundwater monitoring well MW-6 and Piezometer P-4 this quarter <br /> Groundwater elevation data is presented as Table One <br /> Groundwater elevation (potentzometrfc 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 0 0024-feet/foot A shallow zone <br /> potentiometric 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 0 0031-feet/foot <br /> The groundwater flow to the deep zone (greater than 100-feet) flows <br /> • toward the east this quarter at a gradient of approximately 0 00091 <br /> feet/foot <br /> Potentiometric surface differences in wells adjacent to each other b u t <br /> screened 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 September 25 and 26, 2002, ASE collected groundwater samples from <br /> fourteen (14) of the on-site and off-site groundwater monitoring wells for <br /> analysis The number of wells to be sampled each quarter was proposed in <br /> ASE's letter to the San Joaquin County PHS-EHD dated September 2, 2001 <br /> and approved during a subsequent telephone conversation with Lori <br /> Duncan of the PHS-EHD <br /> Prior 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 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 — September 2002 Sampling <br /> -2- <br />