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� <br /> DAVID L.NELSON AND ASSOCIATES, INC. <br /> Consulting Enginecring Gcolugy <br /> f# <br /> Ic� May 31 , 1991 <br /> Project No. 4791 <br /> Page 9 <br /> t� <br /> 4. All footings should be sized according to the anticipated <br /> wall or column loadings, and the above soil bearing values. <br /> fR Minimum footing widths of 14 and 20 inches are recommended <br /> ; for all continuous and isolated footings, respectively. <br /> � � 5. All footings should be free of ponded water and sloughed or <br /> , water loosened soils prior to placement of footinq concrete. <br /> Ground settlements due to structural loads should be less than one (1 ) inch <br /> �� total and one-half (1/2) inch differential over the building area. <br /> I <br /> {a We recommend that footing areas be inspected by the consultar.t prior to <br /> � placement of concrete to verify that bearing soil type and conditions are <br /> � � consistent with the recommendations of this report. <br /> � <br /> During periods of wet weather or in saturated so�i �onditions, special <br /> I � <br /> I measc-es may be required to fac:litate construction. Interim excavation <br /> grading should be sloped to prevent ponding. It should be noted that the on- <br /> � � site fill soils, surface soils, weathered zone materials and basal glacial <br /> I � <br /> till deposits are considered highly moisture sensitive, and may tend to <br /> j , deteriorate if worked during rainy weather or in a saturated condition. <br /> � � Delays in construction activity may result from a deteriorated soil condition. <br /> if necessary, the use of a covering of crushed rock or pit run gravel over the <br /> � �. subgrade soils to minimize disturbance and softening of the bearing soils <br /> during construction. The thickness of the rock or gravel will be dependent on <br /> + n the material being protected, and its use. <br /> � Pressures On Subgrade Walls <br /> 19 <br /> The design lateral earth pressures acting on retaining walls are a function o <br /> � the type of wall (for example, yielding or non-yielding) , the method of <br /> � `� construction, and the type of soil used behind the wall. For planning <br /> � purposes for fixed or non-yielding walls, we recommend that the "at rest" <br /> �� condition should be assumed, and that an equivalent fluid pressure of 50 <br /> pounds per cubic foot (pcf) be used for design purposes. For yielding walls, <br /> !� <br />