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• (4) Continuous foundation walls should be reinforced top and bottom to span an unsupported <br />length of at least 10 feet. <br />(5) Areas of loose or soft soils encountered within the foundation over-excavation should be <br />removed and the foundation should be extended to adequate bearing soils. Excavations <br />for new fill placed to support foundations should extend down from the edge of the <br />foundation at a 1:1 slope. <br />Where excavations expose oversized materials (6-inches plus), these should be removed <br />from the subgrade in order to prevent point loading under foundations. <br />(6) Care should be taken when excavating the foundations to avoid disturbing the supporting <br />soils. <br />('7) A representative of the geotechnical engineer should observe all footing excavations prior <br />• to concrete placement. <br />FLOOR SLABS <br />Floor slabs present a difficult problem where expansive soil materials are present because <br />sufficient dead load cannot be maintained on the slab to resist the uplift pressure generrted when <br />the subgrade soils are wetted and expand. The potential for and risk of floor slab movement can <br />be reduced by the provision of at least 3 feet of select, non-expansive materials as discussed <br />previously. We believe slab-on-grade construction may be used, provided the risk of distress <br />resulting from slab movement is accepted by the owner. Several swell-consolidation test results <br />indicated very high expansion potential, for example, the samples from a depth of 4 feet in <br />Boring 5 and 9 feet in Boring 6 swelled 8.4 and 13.2 percent, respectively. Seven other samples <br />~• 24 <br />