6500 MERRILL CREEK PKY BASE FILE 2016-01-01 MF Import

f, ) � . --, -� --, The Quadrant Corporation .1N 95292 September 28, 1995 Page 5 The values given above are to be used to design permanent foundation and retaining walls only. The passive pressure given is appropriate for the depth of level, structural fill placed in front of a retaining or foundation wall only. We recommend a safety factor of at least 1.5 for overturning and sliding, when using the above recommended values to design the walls. The design values given above do not include the eftects of any hydrostatic pressures behind the �valls and assume that no surcharge slopes or loads, such as vehicles, will be placed behind the walls., If these conditions exist, those pressures should be added to the above lateral soil pressures. Also, if sloping backfill is desired behind the walls, we will need to be given the wall dimensions and the slope of the backfiil in order to provide the appropriate design earth pressures. The surcharge due to traftic loads behind a wall can typically be accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active iluid density. . . Heavy construction equipment should not be operated behind retaining and foundation walls within a distance equal to the height of a wall, unless the walls are designed for the additional lateral pressures resulting irom the equipment. The compaction of backfill near the walls should be accomplished with hand-operated equipment to prevent the walis from .+ being overloaded by the higher soil forces that occur during compaction. Retaining Wall Backfill Backfill placed behind retaining or foundation walls should be coarse, free-draining, structural fill containing no organics. This backfill should contain no more than 5 percent silt or clay particles and have no gravel greater than 4 inches in diameter. The percentage of particles passing the No. 4 sieve s:hould be between 25 and 70 percent. The purpose of these backfili requirements is to ensure that the design criteria for a retaining wall are not exceeded because of a build-up of hydrostatic pressure behind the wall. The top 12 to 18 inches of the backiiii should consist of a relatively impermeable soii or topsoil, or the surface should be paved. The sub-section entitled General Earthwork and 3tructural Fill contains recommendations regarding the placement and compaction of structural fill behind retaining and foundation walls. The above recommendations are not intended to waterproof the below-grade walis. If rcioist cnnditions or some seepage through the walls are not acceptable, damp-proofing or waterproofing should be provided. This could include limiting cold-joints and wall penetrations, and possibiy using bentonite panels or membranes on the outside of the walls. Applying a thin coat of asphalt emulsion is not considered waterprooiing, but it will help to prevent moisture, generated from water vapor or capiilaiy action, from seeping through the concrete. c�eo n;ci i consvi:inN is,rrvc