10200 19TH AVE SE COSTCO FUEL STATION 2016-01-01 MF Import

GEOTECHNICAL ENGINEERING STUDY � Costco `Nholesale � c/o Barghausen Consulting Engineers E-8556 January 13, 1999 Page 8 Permanent Retainina and Foundation Walls Retaining and foundation walls should be designed to resist lateral earth pressures from the retained soils, and any surcharge loading. For walis designed to yield a minimum of 0.002 times the height of the wall, lateral earth pressures can be calculated using an equivalent fluid with a unit weight of thirty-five (35► pounds per cubic foot (pcf). For non-yielding walls, the equivalent fluid pressure should be increased to fifty (50) pcf. The above lateral earth pressure values assume horizontal backfill conditions. The above lateral earth pressure values assume no surcharges dua to traffic, adjacent foundations, construction loads, or otner loading. If surcharges are to apply, they should be added to the above design lateral press�res. A two-foot soil surcharge should be used to account for traffic surcharges, where applicable. The walls should be provided with a perfo�ated drainpipe and backfilled with a free-draining material. The free-draining material should extend at least eighteen (18) inches behind the wall. The remainder of the backfiil should consist of structural fill. The use of a sheet drain such as Mira-Drain 6000 or equivalent can be considered in lieu of free draining backfill. Slab-on-Grade Floors Slab-en-grade floors should be supported on at least one foot of structural fill or on competent native soil. Loose or unstable subgrade soils should be stabilized prior to construction of the slab. The use of a geotextile and rock ballast, or cement kiln dust treatment can be considered for stabilizing the subgrade soils, if necessary. Concrete slabs supported on soil ultimately may cause the moisture content of the underlying soils to rise. This results from continued capillary rise and the presence of the slab which impedes normal evapotranspiration of soii nwisture. Because the concrete is permeable, moisture will eventually penetrate the slab resulting in a condition commonly known as a "wet slab", and poor adhesion of floor coverings may result. In areas where a "wet slab" may be detrimental to interior finishes, moisture protection measures should be used. Various alternatives exist, including concrete toppings or additives and synthetic moisture-resistant membranes. Information on the product usage, installation and warranty should be obtained from the manufacturer if these products are used. The effectiveness of such measures can be improved by installing a capillary break under the membrane or damp-proofed slab. Eanh Cansuhonts, Inc. l�