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August 28, 1991 BALBI&CHANG ASSOCIATES <br /> File No. 1525-69 <br /> surface. This major silty/clayey soil layer generally grades damp, medium stiff to very stiff, <br /> and low plasticity. Some sandy soils exist within this major layer. <br /> i <br /> I <br /> D. Groundwater Conditions <br /> No free groundwater was observed in any of the test,borings to their maximum explored <br /> depths at the time of our field exploration. Information from the Environmental Health <br /> Division of San Joaquin County and the property owner indicates the localized depth to first <br /> groundwater table is approximately 50 to 70 feet below the existing ground surface. <br /> Groundwater conditions at the site are expected to fluctuate in the future due to factors such <br /> as seasonal rainfall, groundwater pumping and recharging, seepage conditions and <br /> construction activities. However, the influence of these factors could not be determined at <br /> the time of our investigation. <br /> III. DISCUSSIONS AND CONCLUSIONS <br /> Our investigation program indicates the primary:geotechnical`concern of this project site is <br /> the near surface expansive soil. The major problem associated with the highly expansive soil <br /> is.the significant volumetric changes due to-the cyclic shrinkage and swelling. .Structure <br /> founded on expansive soil stratum may experience structural distress-during its useful life. <br /> Therefore, it is important to eliminate or to minimize the effects of expansive soil on the <br /> proposed structure. <br /> i <br /> There are several approaches, such as replacing the expansive soil with nonexpansive <br /> material, chemical treatment, deep foundation, or raised floor system, may be employed to <br /> reduce the potential of structure distress. Based on the proposed building function, the light <br /> building loads, the availability of a nearby source of select nonexpansive material, and the <br /> economical benefits, it is our opinion that the lime treatment method may be the most feasible <br /> solution for this site. <br /> The expansive site soil beneath the proposed Mini-Market building may be properly treated <br /> with lime to reduce expansion potential prior to foundation construction. After lime treatment <br /> is properly performed and the results are verified, the Mini-Market building may be supported <br /> by conventional spread footings. Another benefit of lime treatment is the increase of soil <br /> Page 4 of 17 <br />