1515 132ND ST SE Geotech Report 2022-10-25

Proposal for Geotechnical Engineering Services Proposed Bank: 1515 132°d Street Southeast, Everett, Washington March 15, 2019 soil or on structural fill. Any over -excavations, if needed, should be backfilled with structural fill. Interior concrete slab -on -grade floors should be underlain by a capillary break consisting of at least of 4 inches of pea gravel or compacted 3/-inch, clean crushed rock (less than 3 percent fines). The capillary break material should meet the gradational requirements provided in Table 2, next page. Table 2 — Capillary Break Gradation Sieve Size Percent Passing 3/ -inch 100 No. 4 0 — 10 No. 100 0-5 No. 200 0-3 The capillary break should be placed on the subgrade that has been compacted to a dense and unyielding condition. A 10-mil polyethylene vapor barrier should also be placed directly below the slab. Construction joints should be incorporated into the floor slab to control cracking. 5.4 RETAINING WALL DESIGN PARAMETERS Retaining walls should be designed to resist the lateral earth pressures exerted by the soils behind the wall. Proper drainage provisions should also be provided behind the walls to intercept and remove groundwater that may be present behind the wall. Our geotechnical recommendations for the design and construction of retaining walls are presented below. 5.4.1 Lateral Earth Pressures Cantilever walls should be designed for an equivalent fluid pressure of 35 pcf for a level backfill condition behind the walls assuming the walls are free to rotate. If the walls are restrained at the top from free movement, such as basement walls with a floor diaphragm, an equivalent fluid pressure of 45 pcf should be used for a level backfill condition behind the walls. Permanent walls should be designed for an additional uniform lateral pressure of 7H psf for seismic loading, where H corresponds to the buried depth of the wall. 19-049 1515 132nd St SE Page 8 PanGEO, Inc.