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KLEINFELDER No free groundwater was encountered in any boring drilled for this investigation. Regional groundwater maps suggest that groundwater is below the 70 to 80 foot depth. It is possible that changes in groundwater conditions will occur at the site in the future because of variations in irrigation, rainfall, groundwater withdrawal, construction activities, or other factors not apparent at the time our borings were drilled. The above are general summaries of the soil and groundwater conditions encountered in the borings drilled. More-detailed descriptions of the soils encountered in the borings are noted on the Logs of Borings. All soils have been classified according to the Unified Soil Classification System which is described on Plate A-2 of the appendix. VII. LABORATORY TESTING An Atterberg Limits test was performed on a sample obtained from the borings in order to evaluate the expansion characteristics of the soils encountered. The test result is noted on the Log of Boring at the corresponding sample location and is summarized on Plate A-10 of the appendix. VIII. CONCLUSIONS AND RECOMMENDATIONS 1. General The surface soils encountered in the borings drilled consisted of dark gray-brown to red-brown silts and clays. Based on our laboratory tests and experience, the clay soils are expansive. Foundations and concrete slab-on-grade floors placed on the clay soils would be subject to possible damage resulting from heaving or shrinking of the clay soils because of moisture changes. However, in our opinion the proposed structures can be supported on the existing soils provided that the recommendations presented in this report are followed. We recommend that concrete slab-on-grade floors be underlain by nonexpansive Engineered Fill and/or moisture- conditioned existing soils in order to reduce the risk of differential movement because of heaving or shrinking of the clay soils. Recommendations for foundations, support of concrete slab-on-grade floors, site preparation and grading, moisture conditioning, pavement sections, and other items are presented in the following subsections of this report. 20-4280-O I.G0 112019R 150 Page 3 of 12 April 14, 1999 Copyright 1999 Kleinfelder,Inc.