1010 N BROADWAY STARBUCKS 2025-07-24

Geotechnical Engineering Evaluation lierracon Broadway& 10th Starbucks Everett, WA January 9, 2014 Terracon Project No. 81135080 well-graded sand and gravel, such as "Ballast" per WSDOT: 9-03.9(1) or "Gravel Borrow" per WSDOT: 9-03.14. Alternatively, an angular material such as "Crushed Surfacing Base Course" per WSDOT: 9-03.9(3) or 2-inch-minus crushed rock ("railroad ballast") could be used, although these materials would likely be more expensive. In the interest of using recycled materials, it would also be acceptable to use crushed cement concrete, provided that it meets the same textural criteria as the aforementioned WSDOT materials. Base Course (Capillary Break): A base course, or capillary break, is a layer of relatively porous material placed beneath floor slabs to retard the upward wicking of groundwater, as well as to provide a smooth bearing surface. Ideally, the base course would consist of clean, uniform, well-rounded gravel, such as 5/8-inch or 7/8-inch washed rock. It would also be acceptable to use a clean, angular gravel such as "Crushed Surfacing Base Course" per WSDOT: 9-03.9(3) for this purpose. Floor Settlements: If the subgrade and floor layers are properly constructed, we estimate that total post-construction settlements of the slab-on-grade floor will not exceed 1/2 inch. Differential settlements across the length or width of the floor could approach two-thirds of the actual total settlement. Subgrade Verification: Floor slabs should never be cast atop loose, soft, organic, or frozen soil, slough, debris, uncompacted fill, or surfaces covered by standing water. We recommend that the condition of all subgrade areas be verified by a Terracon representative before any underslab fill is placed, and then again before the slab is poured. 5.5 Drainage Systems In our opinion, the new development should be provided with permanent drainage systems to reduce the risk of future moisture problems. We offer the following recommendations and comments for drainage design and construction purposes. Foundation Drains: Due to the possibility of the formation of perched shallow groundwater above the relatively shallow glacial till soils, we recommend that the building be encircled with a perimeter foundation drain to collect exterior seepage. This drain should consist of a 4-inch- diameter perforated pipe within an envelope of pea gravel or washed rock, extending at least 6 inches on all sides of the pipe. The gravel envelope should be wrapped with filter fabric (such as Mirafi 140N) to reduce the migration of fines from the surrounding soils. Ideally, the drain invert would be installed no more than 8 inches above or below the base of the perimeter footings. Runoff Water: Roof downspouts, parking lot drains, and drains from any other runoff surfaces should not be tied into the perforated piping system of the foundation drain. Instead, the runoff water collected from such sources should be routed through a separate tightline piping system. Reliable Responsive - Convenient a Innovative 10