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4 <br /> 2 . 0 GROUNDWATER FLOW DIRECTION AND GRADIENT <br /> On March 12, 2001, 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 free- <br /> floating hydrocarbons or sheen using an oil/water interface probe and a <br /> product thickness bailer No free-floating hydrocarbons or sheen were <br /> observed in any monitoring well Groundwater elevation data is presented <br /> 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 flow ASE installed a "pump and <br /> treat" interim remediation system in September 2000 to influence t h e <br /> offsite downgradient flow pattern in the shallow zone The remediation <br /> system is causing a "coning effect" in the northern portion of the site <br /> Groundwater is flowing toward the recovery wells <br /> Groundwater in the middle zone (55-70-feet bgs) appears to flow to the <br /> southwest with a gradient of approximately 0 0012-feet/foot, which is <br /> consistent with previous findings The groundwater flow in the deep zone <br /> (greater than 100-feet) also appeared to flow to the southwest at a very <br /> flat gradient of approximately 0 00078-feet/foot Potentiometric surface <br /> differences in wells adjacent to each other but screened in different zones <br /> (such as monitoring wells MW-6, MW-7 and MW-8) show a decreasing <br /> hydraulic head with depth, suggesting the potential for downward <br /> groundwater flow <br /> 3 . 0 GROUNDWATER SAMPLE COLLECTION <br /> On March 12 and 13, 2001, ASE collected groundwater samples from the <br /> site monitoring wells for analysis Prior to sampling, the site monitoring <br /> wells were purged of four well casing volumes of groundwater using a <br /> Grundfos pump and/or dedicated bailers The pH, temperature, and <br /> conductivity of the purge water were monitored during evacuation, a n d <br /> samples were not collected until these parameters stabilized Samples <br /> were collected from the wells using dedicated bailers The groundwater <br /> samples were decanted from the bailers into 40-m1 volatile organic <br /> analysig, (VOA) vials, preserved with hydrochloric acid and sealed without <br /> headspace. All of the samples were labeled and stored on ice for <br /> transport to Kiff Analytical, LIC of Davis, California (ELAP #2236) under <br /> appropriate chain-of-custody documentation Well sampling field logs are <br /> Frank's One Stop Quarterly Report — March 2001 Sampling <br /> -2- <br />