1010 N BROADWAY STARBUCKS Geotech Report 2025-07-24

• Geotechnical Engineering Evaluation lierracon Broadway& 10th Starbucks Everett,WA January 9, 2014 ®Terracon Project No. 81135080 These include using thicker sections to account for the construction traffic; using some method of soil stabilization to improve the support characteristics of the pavement subgrade; routing heavy construction traffic around paved areas; or delaying paving operations until as near the end of construction as is feasible. 5.7 Structural Fill The term structural fill refers to any materials placed under foundations, slab-on-grade floors, sidewalks, pavements, and other such features. Our comments, conclusions, and recommendations concerning structural fill are presented in the following paragraphs. Structural Fill Materials: For general use, a well-graded mixture of sand and gravel with a low fines content (commonly called "gravel borrow" or"pit-run") provides an economical structural fill material. For specialized applications, it may be necessary to use a highly processed material such as crushed rock, quarry spalls, clean sand, granulithic gravel, pea gravel, drain rock, controlled-density fill (CDF), or lean-mix concrete (LMC). Recycled asphalt or concrete, which are derived from pulverizing the parent materials, are also potentially useful as structural fill in certain applications. Soils used for structural fill should not contain any significant amount of organic matter or debris, nor any individual particles greater than about 4 inches in diameter. Soil Moisture Considerations: The suitability of soils used for structural fill depends primarily on their grain-size distribution and moisture content when they are placed. As the fines content (that soil fraction passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small changes in moisture content. Soils containing more than about 5 percent fines (by weight) cannot be consistently compacted to a firm, unyielding condition when the moisture content is more than 2 percentage points above or below optimum. On-Site Soils: Because only minor cuts are planned for the site after stripping of the asphalt, we expect that only minor quantities of on-site fill soils will be generated during earthwork activities. Our borings indicated that the upper on-site soils will likely consist of silty sand with gravel. At the time of our exploration, moisture contents in the upper fill zone were around 7 percent, which we infer to be near their optimum moisture content. As such, most on-site fill soils will likely be reusable during dry weather if they can be adequately moisture-protected, but they may be difficult to reuse during wet weather. Glacial till soils encountered below the existing fill are moderately to very moisture sensitive and may not be reusable during wet weather. Any zones containing significant amounts of wood, asphalt, or other waste products should be excluded from reuse as structural fill. Wet-Weather Earthwork: As discussed above, the on-site fill and glacial till soils may be difficult to reuse as structural fill during wet weather. Consequently, the project specifications should include provisions for using imported, clean, granular fill. As a general structural fill material, we recommend using a well-graded sand and gravel such as "Ballast" or "Gravel Reliable ® Responsive ® Convenient m Innovative 14