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Addendum to the Well Installation and Hydraulic Testing Report and Additional ARCADIS Well Installation Work Plan Former Occidental Chemical Corporation Lathrop, California 4. Comparison between Hydraulic Testing Data and Model Predictions The hydraulic testing data from EW-09 provided data that can be compared to the groundwater modeling input parameters to verify or refine modeling results. Data from the hydraulic testing indicated that the water table zone aquifer has a hydraulic conductivity of approximately 38 ft/day and transmissivity of 1,138 ftz/day.These values are slightly lower than the simulated aquifer parameters that were used in the groundwater model. In the model,the hydraulic conductivity of the water table zone was estimated to be 45 ft/day and the transmissivity of the water table zone was estimated to be 1,350 ftZ/day. For comparison, hydraulic conductivity values simulated in the model for the shallow, intermediate, and deep zones were 30 ft/day, 15 ft/day and 75 ft/day, respectively. Hydraulic conductivity values are based on calibration of the groundwater model to December 2011 water level elevations. As presented previously in Section 2 and Figure 4, distance versus drawdown was plotted to estimate a radius of influence of approximately 700 to 750 ft. Similarly,the groundwater model can be used to estimate the zone of influence of water table zone extraction wells(Appendix C).To provide a direct comparison between the hydraulic test conditions and groundwater model, a special model simulation was run that reflected actual pumping conditions at the Site on January 12 and 13, 2012. The predicted capture zone associated with the water table zone extraction well EW-09 is shown on Figure 6.The model simulation predicts a radius of influence of approximately 1,500 ft. Figure 6 illustrates the zone of capture within the water table zone that considers the additive influence of all the Site extraction wells located in the water table zone, shallow, intermediate and deep zones.The model-predicted capture extent is larger than estimated using the drawdown from the pumping test due the differences in the methods of analysis.The modeling evaluates all the extraction wells, aquifer heterogeneities, and three- dimensional capture,while the local pumping data assesses the effects of two-dimensional capture of a single well in a homogeneous aquifer.The zone of capture is shown with an outline of the extent of groundwater currently affected by sulfolane. Groundwater modeling predictions of zones of influence for all Site extraction wells under future pumping scenarios are shown by zone in Appendix C. 5. Groundwater Quality Near INJ-12 In the Report and Work Plan,ARCADIS proposed to install injection well INJ-12 in the vicinity of the Simplot BSW. Due to recent water quality findings described below,ARCADIS proposes to modify the planned location and extraction rate of INJ-12 (Figure 7). Recent Groundwater Quality Results In January 2012,ARCADIS collected samples from Simplot's primary supply well (PSW)and BSW and analyzed them for Site CDCs: sulfolane, DBCP, and EDB. None of these compounds were detected in 2012-0313 addendum well install work plan_hy test rpt.dmx 7