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J. C. Penney Company, Inc.C. 0, <br />Page 2 <br />November 22, 1971 <br />(Our Job No. A-71009) <br />Water was measured in the borings, which were drilled in January, <br />1971, as shallow as ten feet below the existing grade, corresponding to <br />Elevation 22. The elevation of the water table is known to vary within <br />this area, and the water level may be higher or lower during construction. <br />RECOMMENDATIONS <br />General <br />The soils at basement level vary from soft to moderately firm. In <br />addition, the water level could rise. to above the elevation of the basement <br />level. We recommend that the site be dewatered as necessary to allow foun- <br />dations for the basement and elevator pit to be constructed in the dry. If <br />the site is properly dewatered, conventional spread footings may be used. <br />The excavation may extend into soft soils, and the water level is <br />relatively shallow. Accordingly, the subgrade soils may become spongy, and <br />excavation my be difficult at basement level.However, the soils should <br />not be allowed to dry out and crack after excavation due to exposure to the <br />air. <br />To prevent hydrostatic pressures developing on the basement walls <br />and floor, we recommend that a permanent subdrain system be installed be- <br />neath the basement floor and behind the walls.Recommendations for foun- <br />dation and basement wall design and for a subdrain are presented in the <br />following sections. <br />Foundations <br />If the.site is properly dewatered and the foundations are constructed <br />in the dry, conventional .spread footings may be used. Spread footinqs should <br />be established at a depth of at least two feet below the adjacent floor level. <br />Continuous wall footings may be designed to impose a dead plus live load pres-sure of 800 pounds per square foot.Isolated column footings may be designedto impose a dead plus live load pressure of 1,000 pounds per square foot. A <br />one-third increase in the bearing values may be used when considering wind.orseismic loads. <br />The soils at basement level may be relatively soft and could even <br />become spongy due to the shallow water level. Footing excavations shouldbe inspected to verify the presence of satisfactory undisturbed natural soils <br />RECEIVED <br />,DEC 1 1971 <br />City of Sanio a <br />D.pt. Bldg. Sfty. 8 Mew,Ing