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M03107GE of the bottom of the footing below the lowest adjacent grade of at • least one (1) foot on all sides of the footings. The minimum depth of embedment is sufficient only to develop the bearing capacity for design purposes. Actual design and construc- tion should result in interior footings with one (1) foot or more embedment and exterior footings with frost depth or more embedment. Typically deeper embedment will increase bearing capacity and de- crease post construction settlement and decrease the influence of expansive soils. The soil sample tested had a measured swell pressure of about 200 to 1,600 pounds per square foot. when wetted the site soil materi- als have the ability to raise supported foundation members with loads less than the swell pressure. The foundation design should be as rigid as possible with as high of a dead load as can be available. The greater the dead load on the footings the less the potential for movement from the foundation soils should they become wetted. If the soils become wetted they will swell and will raise the foundation portions supported on the wetted soils. If the structure is supported on spread footings the owner must realize that post construction movement of the footings is likely. We are available to discuss the implications of supporting foundations on swelling soils. Interior column loads supported on spread footings which are • structurally connected to the other foundation members will provide more uniform performance of the interior footings with respect to the other foundation members and will help reduce the potential differential settlement between interior and exterior foundation members. The foundation walls should be designed to act as beams to distribute stresses associated with volume changes of soils. The-beam design should be addressed by the project structural engineer. Exterior column supports should be supported by foundations incorporated into the foundation system of the structure not supported on flatwork. Column supports placed on exterior concrete flatwork may move if the support soils below the concrete slab on grade become wetted and swell or freeze and raise or settle. Differential movement of the exterior columns may cause stress to accumulate in the supported structure and translate into other portions of the structure. The estimated post construction settlement and swell potential may be reduced by placing the footings on a blanket of compacted structural fill. The estimated post construction settlement and associated thickness of compacted structural fill are presented below. 12 • 3ilambert ana ~,~,~oriates CO NSUITING GEOtECHNICAI ENGINEERS AND MATE RIAI TESTING