2701 ROCKEFELLER AVE NIMBUS Geotech Report 2023-12-29

Opportunity Zone Development LLC June 6, 2019 JN 19152 Page 12 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 from the equipment. The values given above are to be used to design only permanent foundation and retaining walls that are to be backfilled, such as conventional walls constructed of reinforced concrete or masonry. It is not appropriate to use the above earth pressures and soil unit might to back -calculate soil strength parameters for design of other types of retaining walls, such as soldier pile, reinforced earth, modular or soil nail walls. We can assist with design of these types of walls, If desired. The passive pressure given is appropriate only for a shear key poured directly against undisturbed native soll, or for the depth of level, well -compacted fill placed in front of a retaining or foundation wall. The values for friction and passive resistance are ultimate values and do not include a safety factor. Restrained wall soll parameters should be utilized the wall and reinforcing design for a distance of 1.5 times the wall height from corners or bends in the walls, or from other points of restraint. This is intended to reduce the amount of cracking that can occur where a wall is restrained by a corner. Wall Pressures Due to Seismic Forces The surcharge wall loads that could be Imposed by the design earthquake can be modeled by adding a uniform lateral pressure to the above -recommended active pressure. The recommended surcharge pressure is 8H pounds per square foot (psf), where H is the design retention height of the wall. Using this Increased pressure, the safety factor against sliding and overturning can be reduced to 1.2 for the seismic analysis. Hetelnino Wall Backflll and Weteroroo/Ina Backfill placed behind retaining or foundation walls should be coarse, free -draining structural fill containing no organics. This backgll 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 should be between 25 and 70 percent. Drainage composite similar to Miradrain 6000 should be placed against the backfilled retaining walls. The drainage composites should be hydraulically connected to the foundation drain system. Free -draining backfill should be used for the entire width of the backfill where seepage is encountered. For increased protection, drainage composites should be placed along cut slope faces, and the walls should be backfilled entirely with Free -draining soil. The later section entitled Drainage Considerations should also be reviewed for recommendations related to subsurface drainage behind foundation amd retaining walls. The purpose of these backfill 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. Also, subsurface drainage systems are not Intended to handle large volumes of water from surface runoff. The top 12 to 18 Inches of the backfill should consist of a compacted, relatively impermeable soll or topsail, or the surface should be paved. The ground surface must also slope away from backfilled walls at one to 2 percent to reduce the potential for surface water to percolate Into the backfill. Water percolating through pervious surfaces (pavers, gravel, permeable pavement, etc.) must also be prevented from flowing toward walls or into the backfill zone. Foundation drainage and waterproofing systems are not intended to handle large volumes of Infiltrated GEOTECH CONSULTBNrS, INC.