1901 MERRILL CREEK PKY 2018-01-01 MF Import

Based on the nature of the glacially deposited soils, it is likely that perched ground water seepage will be encountered at poRions of the slab subgrade elevation. Therefore, we recommend that a capillary break material consisting of at least 6 incha of impoRed free-draining � coarse sand (larger than No. 40 sieve size) and gravel containing less than 5 percent fines be placed beneath the slab. The sand and gravel should be compacted to at least 95 percent of the � MDD (ASTM D-1557). A vapor barrier should be placed beneath all on-grade floor slabs. The vapor bazrier shouid jbe placed irtunediately below the slab. This vapor barrier should consist of polyethylene sheeting and can be overlain by a 2-inch thickness of clean sand. � �' RETAINING SYSTEMS General We have outlined several altemative retention systems in the following sections, including rockery walls,crib walls,concrete cantilever retaining walls,structural earth walls and permanent shoring walls. For walls constructed in cuts made in dense native till soils, or in sttuctural fill areas where less than 4 fat of fill will be required, we anticipate that rockery walls will provide the most cost effective earth retention system. If the proximiry of existing structura or other . lr3 right-of-way constraints preclude the construction of rcekeries, pem�anent shoring walls will provide the least amount of ground disturbance behind the waU. Structural earth walls provide a a cost effective retention system for fill embacilanents. Concrete cantilever walls might also be considered in fill areas. Retaining structures constcucted on slopes should have an adequate embedment below the (.� ground surface. In general, for slope heights of less than 20 feet, the embedment below the , ground surface should be sufficient to provide a minimum footing setback of one footing width or 5 feet, whichever is greater, from the slope. We recommend that both internal and global stability be evaluated during design of the. walls. Desig� Parameters ' Retaining walls that are allowed to yield during backfilling(such as conventional cantilever retaining walls) should be designed for lateral pressures based on (active) equivalent fluid densities adjusted for the backslope of the ground sv:face behind the retaining wall. Equivalent fluid densities of 35, 40, and 55 pounds per cubic foot(pc� should be used for level backslopes, 4H:1V backslopes and 2H:1V backslopes, rapectively. These values apply to fili behind the walls that is placed and compacted az recommended previously,with the exception that fill wi[hin a distance equal to the wall height behind the wall shuuld be compacced to between 9� � 92 percent of maximum dry densiry so as not to overstras the wall. Care must be taken by the contractor to avoid overcompaction. Lateral prasures induced by surcharga ue not included ' in the equivalent fluid densiry values recommended above. 1'he effects of surcharge loads should be included as appropriate. G e o E n � i n e e r s 11 FileNe. l�60-00�17•��7a��'7