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File No. 20-1100-38 KLEINFELDER September 12, 1996 Groundwater was encountered at a depth of approximately 62 feet below existing ground surface in Boring B-2 at the time our borings were drilled. No free groundwater was encountered in the Teichert boring TRNA-5 which was drilled to a depth of 69 feet. According to Teichert, an existing onsite well drilled in 1992 had a groundwater depth of 88 feet. The adjacent Rose property is being mined to at least 70 feet and has not encountered groundwater. Based on these observations, the groundwater encountered in Boring B-2 is most likely a perched condition not representative of actual groundwater depths. We note that it is possible that groundwater conditions at the site may vary in the future because of variations in rainfall, irrigation, runoff, or ` other factors not apparent at the time our borings were drilled. The above is a general summary of the soil and groundwater conditions encountered in the borings drilled at the site. More detailed descriptions of the soils encountered in the borings are noted on the Logs of Borings, Appendix A, Plates A-3 and A-4. All soils have been classified according to the Unified Soil Classification System (USCS) which is described on Plate A-2 of Appendix A. VI. LABORATORY TESTING Laboratory tests were performed on selected samples obtained from the borings in order to evaluate the strength characteristics of the soils encountered. The tests performed consisted of Direct Shear tests. The results of these tests are noted on the Logs of Borings at the corresponding sample locations and test results are presented on Plates A-5 through A-7 of Appendix A. r VII SLOPE STABILITY ANALYSIS As in previous studies for other nearby quarry operations, we have relied on the performance of existing slopes and on strength tests performed on relatively undisturbed samples to evaluate input values for our computer analyses. An example of existing slopes studied is an approximately 60- foot high, near-vertical (78 degree) slope at Teichert's Tracy facility, west of the site. Laboratory strength tests have not been performed on any of the gravelly materials from the Traina site, as explained in section IV of this report and for this reason, our analyses are conditional on tests being performed during initial excavation of the quarry to confirm strength parameters and soil ` type. The slope stability analyses were performed using the computer programs SLOPE/W. SLOPE/W uses the limit equilibrium theory to compute the factor of safety of earth and rock slopes using the following methods: Ordinary or Fellenius, Bishop's Simplified, Janbu's Simplified, Spencer, Morgenstem-Price, Corps of Engineers, Lowe-Karafiath, General Limit Equilibrium, and Finite Element Stress. Based primarily on the soil conditions and our experience with large existing cuts in similar materials, we anticipate that a wedge or partially circular type failure would be appropriate. In order to evaluate other possibilities, we have also evaluated numerous circular failure conditions as well. 20-1100-381MR960198 Page 3 of 6 01996,Kleinfelder, Inc.