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Project No. 9929.G Geotechnical Investigation/Vineyard Avenue, Pleasanton S August 2003 20. It is noted that since a significant cut is proposed at the estate lot, shrinkage or expansion of the excavated soils is very important. Once the additional boring is performed an evaluation of shrinkage /swell will be made at that time. Cut/Fill Lots 21. Due to the nature of the site and the anticipated grading, it is expected that some of the building pads will be created by cut and fill. Depending on the thickness of the cut or fill, the building subgrade will vary from native soil or bedrock in the cut area to engineered fill. The pad grade will therefore consist of variable engineering characteristics and in an attempt to create a near uniform pad grade for support on a slab type foundation, it is recommended that the cut portion be overexcavated such that the maximum fill thickness differential is no greater that 5 feet. After overexcavation, the exposed surface should be prepared to receive fill as discussed above, and the material recompacted as engineered fill. If a pier and grade beam foundation is used then subexcavation of the cut areas is not needed. Additional recommendations will be made as necessary in the field by the Soil Engineer. Slopes 22. It is recommended that all unsupported cut and fill slopes less than 30 feet in height be constructed at inclinations no steeper than 2:1 (horizontal to vertical). Fill slopes greater than 30 feet in height should be inclined no steeper than 2.5:1. The subsurface materials that will form the 50 foot cutslope planned for the estate lot is not known, but is anticipated to be Livermore Gravel bedrock material, and the cut slope is expected to be preliminarily stable at an inclination of 2.75:1. This will be confirmed during grading or prior to grading when access for a drill rig is available. All cut slopes should be rounded at the upper extremities. Furthermore, it is recommended that all cut slopes in excess of 5 feet in vertical height be observed by the Engineering Geologist during the grading operations. TERRASEARCH, inG Page 17 of 53