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ADDENDUM LETTER -2- ADDITIONAL HYDROGEOLOGICAL INVESTIGATION WORKPLAN MUSCO FAMILY OLIVE COMPANY TRACY, CALIFORNIA Cross-Section A to A' Cross-section A to A' contains MW-1, the most up gradient well on site. Moving north, the interval from GT-2 to GT-1 shows a relatively thick clay that appears to pinch out abruptly at MW-13. Down slope from MW-13 to MW-12 are interbedded materials, with increasing sand and gravel content at MW-5 and MW-12. MW-1 contains relatively low TDS groundwater and shows a fairly consistent groundwater elevation. GT-2 and GT-t found perched groundwater in what appears to be sand lenses encased in clay. MW-13 and MW-3 found groundwater of similar quality whose groundwater elevations are showing similar trends. Although groundwater quality in MW-5 looks similar to groundwater quality in MW-13 and MW-3, the groundwater elevation dropped below the screen on the third sampling event. This well remained dry during the fourth and fifth sampling events. MW-12 is completed in deep groundwater, evident from the Stiff Diagram and the elevation difference between the shallow groundwater. Cross-Section B to B' Cross-section B to B' contains two deep monitoring wells with similar groundwater quality (MW-7 & MW-12). The groundwater rises above the screened interval in MW-7, indicating possible confinement. Groundwater quality in W-2 is similar to MW-1 even though the wells are about a mile apart. Groundwater quality in MW-10 is very similar to MW-13 and MW-3 in cross-section A to A'. The groundwater elevation in MW-10 has dropped to the base of the well screen and subsequently the well was not sampled during the last three sampling events. Cross-Section C to C' Cross-section C to C' contains MW-6, a shallow monitoring well that went dry after the first sampling event. The groundwater quality in this well appears to be similar to the water quality in MW-5. Boring GT-4 encountered no groundwater. MW-9 encountered groundwater but the well went dry after installation. It appears that the well was completed too shallow. MW-11 and W-2 are two adjacent shallow groundwater wells with distinctly different water quality. The groundwater elevations have remained fairly constant in these two wells. Cross-Section D to D' Cross-section D to D' contains two deep monitoring wells with similar groundwater quality(MW-8 & MW-4). The groundwater elevation is substantially above the screens in these wells, suggesting confined conditions. An intermediate groundwater zone was found in Exploratory Boring TW-1. MW-5 and MW-6 were previously discussed.