COMPLIANCE INFO_1968-2006 - Laserfiche WebLink

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SA; 1 SA 1 0 SANITARY LAND FILLS 113 ment takes differential settlement produced by the consolidation and decomposition of the ' r at a much fill caused irregular sags in the sewer line, and the accumulation'of solids partially plugged the pipe. In another case, the settlement was sufficient to f the support Pp cause the sewer to flow backwards. .• is would be If the structures are designed with the anticipation of substantial irregular t lie building movements, settlements of even .a foot or two need not be prohibitive. If the F ;. ) reference structure is heavy and if the old fill is thick, the safest approach is to support 42 ft apart the structure on piles or piers which extend to the virgin material under the onstruction sanitary land fill. If a substantial new fill is required to level the surface or . y new mat- to provide sufficient bearing capacity, this new fill should be added'at least varying in 1 yr and preferably 2 yr before building the structure. By this means the Lively rigid greater part of the settlement will occur before the structure is built. Of Fig. 5 were course, this is most helpful when the structural load is relatively small com- roximately pared to that of the fill. Compaction of the sanitary land fill during its con- 'ill because struction undoubtedly could materially reduce the settlement: It is the fill. As can writer's opinion that the benefits of compaction are so great that research b took place regarding the most effective means of doing this is justified and should be tme at both undertaken. r are equal. The materials most! subject`to irregular settlement or those which resist king on the compaction, such as large debris, large pieces of metal, stumps, and rubber ipated sub- tires should be carefully segregated in areas in which no structural develop- use of the ment is anticipated. While segregation increases the cost, the added.value of }R <• ages and to the land may well exceed the expense, especially in the vicinity of large cities where land is expensive. ft to 15 ft Those materials most easily compacted should be placed in the immediate `fit place dur- building site so that the structures will settle the least possible amount. ' ie building. Finally, the structures built on sanitary land fills must be adapted to € te property settlement. If the framing is structurally flexible and if the partit o'ns are j for making designed so that differential movement can develop between them and the framing, significant differential settlement between adjoining columns can be .t.E ttlement of tolerated. apartment Stability in Slopes.—In some instances sanitary land fills have failed be- , s ft thick. In cause of their own dead weight. Although the fill material itself is light, I "f i it is esti- the soil in the cell walls and the cover is heavier. Moreover, if the loose ` #_ waste becomes saturated from rainfall infiltration the weight increases irregular correspondingly. b tory school Two mechanisms .of failure are: (1) sliding or mud waving on a weak he building foundation soil; and (2) shear through the weak fill itself. Mud waving can up to 3 in., occur if too thick a fill is placed on marshy ground. The shear may break k racked and the cells and expose the waste. This can be predicted in advance from the a ! tructurally foundation strength, and the lift thickness can be adjusted accordingly. When # m dropouts it occurs, it can be minimized by reducing the thickness and placing fill over soil and the the bulges or mud waves. left the thin Sliding is commonplace in deep, uncontrolled fills. In one case a trunk ft deep and sewer was ruptured and several cross-country fuel lines were moved by a .th an auto- slide triggered # by dumping fill on a steep hillside of saturated clay. The .ed out by a shear in this case commenced in the foundation but extended through the fill. ' Steep faces of thick lifts of controlled fill can occur by shear within the ,n and con- fill. The remedy is thinner lifts and flatter outer slopes. )es on such Corrosion and Deterioration.—Because the wastes in the sanitary land fill record, the are active chemically and biologically, they can produce corrosion and de-