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Project No. 9929.G Geotechnical Investigation/Vineyard Avenue, Pleasanton <br />8 August 2003 <br />DISCUSSIONS, CONCLUSIONS, AND RECOMMENDATIONS <br />General <br />1. From a geotechnical and geologic point of view, the proposed residential development is <br />feasible for construction on the subject site provided the recommendations presented in this <br />report are incorporated into the project plans and specifications. <br />2. The most prominent geotechnical feature at the site is the presence of Livermore Gravel <br />at the surface. The most prominent geologic features the pressure of landslide/colluvium areas. <br />3. The landslide/colluvium areas and the creep areas are mapped on Figure 2 and all are <br />outside the proposed development areas. No mitigation of these areas is recommended. <br />4. The hazard from surface fault rupture does not exist in the proposed development; <br />however, the site will be subjected to strong-ground shaking if a significant earthquake event <br />occurs along the Hayward, Calaveras and/or San Andreas Faults. Seismic considerations <br />presented within this report must be integrated in future foundation design. <br />5. The proposed residences maybe satisfactorily supported on either a pier and grade beam, <br />structural mat slab or post-tensioned slab foundation systems. Specific recommendations for <br />each type of foundation system are provided in the Foundation section herein. <br />6. Sulfate compounds in soil can attack concrete and concrete reinforcing. Specialty <br />cements have been developed to resist sulfate attack and are recommended in high-sulfate soils. <br />No sulfate testing was performed on the site as the material that will form the pad grade is not <br />currently known due to the planned extensive grading conditions. We recommend that during or <br />after mass grading is completed that samples be collected at time for an evaluation of sulfate <br />content. <br />TERRASEARCH, inc. Page 12 of 53 <br />