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r `r � KLEIIVFELDER I the embankment construction, our experience in our laboratory indicates that with minimal ' effort, above 85 percent compaction can be easily obtained. { For our slope stability analysis, we have used the same native soil properties as used in our 1997 } report for the cemented clay, sand, and gravel and for the silty sandy clay. These strength ' parameters are also described on the attached cross-sections, Plates 1 and 2. The stability analysis was performed using the computer program SLOPE/W. SLOPE/W uses the limit equilibrium theory to compute the factor of safety of earth and rock slopes.using several. methods. In our previous evaluations for Brown, Granite, and Teichert facilities, we noted that the Bishop's Simplified method generally produced the lowest, or most conservative, factors of safety. For this reason, we have used the Bishop's method for our analysis. Computed factors of safety for the configuration and soil properties analyzed are presented on the attached Plates 1 and 2. We can furnish the actual'computer printout sheets if needed. As noted, the factors of.safety varied from 1.73 for static conditions to a lower value. of 1.32 associated with a seismic event of 0.15G. These values comply with Title Section '9= f 1415.3(K)(4): Two other issues were discussed at our recent meeting with San Joaquin,County. The first dealt with the fact that several of the excavated slopes would have water against the slopes. A concern was raised whether the native soils could become saturated which might reduce the soil strength properties used in our analysis. Recently our firm drilled monitoring wells at the bottom of the existing Teichert pit in Tracy. Even though both monitoring wells were placed within approximately 10 feet from the edge of the existing pond, groundwater was actually measured in the wells approximately 13 feet below the adjacent pond level. In other words, due to the generally cemented nature of.the sandy and gravelly soils in this area combined with the scaling effect of the silt and clay materials washed into the settling ponds, there is an actual hydraulic separation between the groundwater and the water level in the pond. For this reason, we do not anticipate any significant effect of water ponding next to the excavated slopes. In addition, we I believe we have also used conservative strength properties for these underlying cemented materials based on back calculations of existing slopes and actual laboratory tests on block samples. The last issue raised was in regards to the number of shallow monitoring wells between the l aqueduct and the proposed settling pond. References is made to our letter dated September 4, 1997 regarding monitoring well installation. At that time we.proposed one shallow monitoring well between the Delta-Mendota aqueduct and the pond. These are relatively shallow monitoring wells, and we understand that San Joaquin County wou prefer that there_e�two f wells. Since the cost should be minimal, we suggest that two shallow wells be installed. i 20-2245-50.G50/2000L219 Page 2 of 3 Copyright 2000 Kleinfelder,Inc. March 13,2000