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' <br /> C3eoCoBual'I'ecFutus Inc Page 2 <br /> Qoundwatei Monaonng Report <br /> Project No 507 2 <br /> March 30,2001 <br /> 1.0 GROUNDWATER MONITORING <br />' 1.1 Hydrogeology of Site <br /> The geology of the site is predominately clays and sandy clays with lesser amounts of silts <br />' and sands The average groundwater elevation was —6 18 feet below MSL on March 12, <br /> 2001 MSL is approximately 7 37 feet below ground surface <br />' A groundwater gradient was calculated for the event and found to be flowing N37°E at <br /> 0 002 ft/ft Gradient direction for the Match 2001 monitoring event is shown in Figure 2, <br /> and the historical groundwater directions and gradients are shown in Figure 3, Groundwater <br />' Gradient Rose Diagram The groundwater elevation data are summarized in Table 1, <br /> Appendix A <br /> ' The groundwater gradient is relatively flat and the direction of groundwater has varied <br /> during the course of the investigation As evident in Figure 3, groundwater has a strong <br /> bifurcated flow regime, trending predominantly to the southwest or northeast at <br /> approximate 180-degree direction reversal The site is quite close to the San Joaquin River <br /> and tidal fluctuations might be responsible for the observed changes in groundwater <br /> direction <br /> 1.2 Gi oundwater Sampling Procedure <br /> On March 12, 2001, Don Light of Del-Tech mobilized to the site to conduct groundwater <br /> monitoring of the eight existing monitoring wells <br /> ' Before sampling attempted the wells were sounded for depth to water and then a clear <br /> P g was p <br /> disposable bailer was used to determine if floating product was present The wells were <br /> purged of at least three well volumes of stagnant water using a dedicated Waterra check-ball <br /> assembly and % inch tubing Purging continued until the temperature, conductivity, and pH <br /> of the groundwater stabilized (c10% variation between three readings), indicating that <br /> ' formation water representative of aquifer conditions was entering the wells These water <br /> quality parameters were measured at intervals of each well volume purged _ <br /> Once purging was complete, a water sample was collected from the Waterra tube Care was <br /> taken to minimize sample agitation Once the sample container was filled and capped, the <br /> 1 bottle was inverted, tapped, and checked for headspace bubbles The sample container was <br /> identified and labeled with a unique designation, inserted into a foam Bolder and placed in <br /> an ice chest cooled to d°C for transport to the laboratory <br />