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<br />(4) Areas of loose or soft material encountered within the <br />foundation excavation should be removed and the <br />footings extended to adequate natural bearing material. <br /> <br />(5) Care should be taken when excavating the foundations to <br />avoid disturbing the supporting materials. Excavation <br />methods which minimize soil disturbance, such as hand <br />excavation or careful backhoe soil removal, may be <br />required in excavating the last few inches. Disturbing <br />the foundation material may result in excessive <br />settlement. <br /> <br />(6) The natural soils may pump or deform excessively under <br />the wheel loads of heavy construction vehicles as the <br />excavations approach footing levels. Construction <br />equipment should be as light as possible to avoid this <br />difficulty. The use of track-mounted vehicles is <br />recommended since they exert lower contact pressures. <br />The movement of vehicles over proposed foundation areas <br />should be restricted. <br /> <br />(7) A layer of lean concrete or gravel shculd be placed in <br />the bottom of foundation excavations prior to steel and <br />concrete placement. This "mud mat" will reduce <br />disturbance of the natural soils caused by construction <br />operations. Disturbing the natural soils will increase <br />settlements. <br /> <br />(8) The proposed foundation elevations appear to be below <br />the water level. Therefore, it may be necessary to <br />dewater the footing excavations during construction. <br />Dewatering should not be conducted by pumping from <br />inside footing limits. This may decrease the <br />supporting capacity of the soils. <br /> <br />(9) The footings should be protected from scour with rip rap <br />or other suitable measures. <br /> <br />(10) A representative of the soil engineer should observe <br />all footing excavations ,prior to concrete placement. <br /> <br />If footings are used they will be placed on the sands and <br />clays. Excavation of the subsoils will have to be conducted <br />in such a manner that the soils beneath the footing are not <br />disturbed or saturated. If the soils are disturbed then the <br />bearing capacity for these soils will be decreased and the <br />amount of settlement will increase. <br /> <br />Foundation Alternatives: A feasible foundation alternative <br />which should be considered is a straight shaft drilled pier <br />system. Construction using drilled piers may reduce the <br />problems associated with construction of the shallow <br />foundations below the water table. If a drilled pier <br /> <br />3 <br />