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M98168GE • consolidation teats were identify the swell poten results were not used to analysis discussed below the formational material strength testa performed material. performed on the samples tested to help :ial of the samples tested however the test predict settlement. The settlement was based on the modulus of elasticity of calculated from an unconfined compressive of a rock core sample of the formational We understand that you require modulus of subgrade reaction to design concrete foundation members for tolerable deflections. We suggest that you consider a modulus of subgrade reaction of 20,000 kips per cubic foot. The modulus of subgrade reaction was calcu- lated from the laboratory stress strain curve from the unconfined compressive strength test and is approximate. We suggest that the modulus of subgrade reaction be verified by plate load tests prior to construction. The site soil samples tested have a measured swell pressure leas than about 100 to 250 pounds per square foot. This swell pressure was measured for soils at the initial moisture content of the soil sample tested. The measured swell pressure may be inf:uenced by disturbance of the sample during the sampling operation an3 the soil suction potential. Changes in the initial moisture content will significantly influ- ence the swell pressure of the site soils. if the initial moisture content of the foundation soils is less than that of the test sample the actual awe'_1 pressures will likely be significantly higher than measured. If the initial moisture content of the foundation soils is greater than that of the teat sample the actual swell pressures may be less than measured. The bottom of the foundation excavations should be thoroughly cleaned and observed by the project Geotechnical Engineer or his representative when excavated. Any loose or disturbed material exposed in the foundation excavation should be removed or remedied prior to additional construction. We recommend that we be contacted to observe the foundation excavations and backfill operations during construction to verify the soil support conditions and our assumptions upon which our recommendations are based. If necessary we may revise our recom- mendations based on our observations. we are available to provide material testing services during the construction phase of the project. 13 lambert ana S~,o~ociaten COYIYLTIMO O[OT[OMYIC~I lYOlMllp •YO Y ~}111Y1L IElfIYO