3632 RUCKER AVE THE LANDING AT PORT GARDNER Geotech Report 2023-04-10

Aug. 31. 2004 3:47PM CHARLES MORGAN & ASSOC, No. 0044 P. 7 - • Grandview Homes, LLC „IN 99040 February 16, 1999 Page 5 accounted for by adding a uniform pressure equal to 2 feet multiplied by the above active fluid 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 from the equipment. The wall design criteria assume that the.backfill will be well-compacted in lifts no thicker than 12 inches. The compaction of backfill near the walls should be accomplished with hand-operated equipment to prevent the walls 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 grave! greater than 4 inches in diameter. The percentage of particles passing the No. 4 sieve should be between 25 and 70 percent. For increased protection, drainage.composites should be placed along cut slope faces, and the walls should be backfilled with pervious soil. 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. The top 12 to 18 inches of the backfill should consist of a compacted, relatively impermeable soil or topsoil, or the surface should be paved. The ground surface must also slope away from backfilled walls to reduce the potential for surface water to percolate into the backfill. The sub-section entitled General Earthwork and Structural 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 walls, If moist conditions or some seepage through the walls are not acceptable, waterproofing should be provided. This typically includes limiting cold joints and wall penetrations, and using. bentonite panels or membranes on the outside of the walls. Applying a thin coat of asphalt emulsion is not.considered waterproofing, but will only help to prevent moisture, generated from water vapor or capillary action, from seeping through the concrete, Excavations and Slopes Excavation slopes should not exceed the limits specified in local, state, and national government safety regulations. Temporary cuts to a depth of about 4 feet may be attempted vertically in unsaturated soil, if. there are no indications of slope instability. Based upon Washington Administrative Code (WAC) 296, Part N, the soil type at the subject site would be classified as Type A. Therefore, temporary cut slopes greater than 4 feet in height cannot be excavated at an inclination steeper than 0.75:1 (Horizontal:Vertical), extending continuously between the top and the bottom of a cut. The above recommended temporary slope inclination is based on what has been successful at other sites with similar soil conditions. Temporary cuts are those that will remain unsupported for a relatively short duration.to allow for the construction of foundations, retaining.walls, or utilities. Temporary cut slopes should be protected with plastic sheeting during wet weather. The cut slopes should also be backfilled or retained as soon as possible to reduce the potential for instability. 43EOTECH CONSULTANTS,INC. /�