2400 33RD ST GEOTECHNICAL INVESTIGATION 2018-01-02 MF Import

SC 130 Milbor-Pita �- 7. This scarified, exposed ground surface shall be moisture conditioned to near optimum, if required, and uniformly compacted to at least 95 percent of the maximum dry density ..7 determined by ASTM: D 1557. The site is now prepared for receiving structural fill or the shallow footings / walkways / pavement subbase materials. 5.1.3 Imported Fill & Compaction The term 'structural fill' refers to any materials used to support foundations, building pads, roadway embankments, utility trench backfill, slab -on -grade floors, sidewalks, pavements sections, and other such features. This term is defined to differentiate it from general filling of a site, which typically is not prepared to support any loading other then landscaping. Compaction to a dense, non -yielding consistent, is critical for a material used as a'structural fill'. Structural fill materials should consist of relatively clean, free draining sand and gravel conforming to the Gravel Borrow (WSDOT 9-03.14(1)) or Select Borrow (WSDOT 9- 03.14(2)) of the 1998 WSDOT Standard Specifications. It may also be called granulithic gravel, pea gravel, washed rock, washed crushed rock, quarry spalls, controlled -density fill (CDF), lean -mix concrete, well -graded mixtures of sand, silt, and gravel, or recycled asphalt, concrete, glass, which is derived from pulverizing the parent materials. Each of these has a potential application as being structural fill, but because they are different sizes and hardening properties, they may not be suitable in all conditions. If earthwork is performed during extended periods of wet weather or in wet conditions, the structural fill should conform to the recommendations provided in the Wet Weather Earthwork section below. In general, we anticipate that the existing fill materials (upper I to 6 feet) on site may be suitable for re -use as dry weather structural fill, providing that organics and pavement materials are removed. Care should be taken to prevent mixing with unsuitable soils, and that the compaction criteria presented herein are met. We recommend against using the underlying clay/silt as structural fill. This fine-grained soil is very moisture sensitive and will be difficult to compact, even under ideal conditions. The silt/clay should be stockpiled for use in landscaped areas or hauled off -site. In general, the structural fill should be placad in eight -inch horizontal lifts and compacted to a dense and firm condition, and at least 95 percent of its maximum dry density, as determined by test method ASTM D 1557 (Modified Proctor). The procedure to achieve the specified minimum relative compaction depends on the size and type of compacting equipment, the number of passes, thickness of the layer being compacted, and certain soil properties. In addition to the horizontal areas of the site, the excavated areas remaining from the emoval of contaminated soil must be compacted structural fill in a similar fashion (8- inch horizontal lifts), so the grade is brought up evenly. Gmlochnica4 Turmcl and Environmental Engines 3080 1251° Ave NE Phone (425, 969-5779 Bellevue, W A 98005 Page 7 Fax (425) 961-0677