2201 100TH ST SW AD SYSTEMS 2022-03-07

GeoTest Services, Inc. April 25, 2017 2201 100th Street Southwest, Everett,WA Job No. 17-0186 Fill and Compaction Structural fill used to obtain final elevations for footings and soil-supported floor slabs must be properly placed and compacted. In general, suitable, non-organic, predominantly granular soil may be used for fill material provided the material is properly moisture conditioned prior to placement and compaction, and the specified degree of compaction is obtained. Material containing topsoil, wood, trash, organic material, or construction debris will not be suitable for reuse as structural fill and should be properly disposed offsite or placed in nonstructural areas. Soils containing more than approximately 5 percent fines are considered moisture sensitive, and are very difficult to compact to a firm and unyielding condition when over the optimum moisture content by more than approximately 2 percent. The optimum moisture content is that which allows the greatest dry density to be achieved at a given level of compactive effort. Reuse of On-Site Soil Near-surface, non-organic native soils may be suitable for re-use as structural fill when placed at or near optimum moisture contents as determined by ASTM D1557 and if allowed for in the project plans and specifications. The Glacial Till soils contain high percentages of fines and should be considered moisture-sensitive. The contractor and owner should be prepared to manage over optimum moisture content soils. Moisture content of the site soils may be difficult to control during periods of wet weather. Imported Structural Fill We recommend that imported structural fill consist of clean, well-graded sandy gravel, gravelly sand, or other approved naturally occurring granular material (pit run) with at least 30 percent retained on the No. 4 sieve, or a well-graded crushed rock. Structural fill for dry weather construction may contain on the order of 10 percent fines (that portion passing the U.S. No. 200 sieve) based on the portion passing the U.S. No. 4 sieve. Accordingly, we recommend that imported structural fill with less than 5 percent fines be used during wet weather conditions. Due to wet weather or wet site conditions, soil moisture contents could be high enough that it may be very difficult to compact even "clean" imported select granular fill to a firm and unyielding condition. Soils with over-optimum moisture contents should be scarified and dried back to more suitable moisture contents during periods of dry weather or removed and replaced with drier structural fill. Backfill and Compaction Structural fill should be placed in horizontal lifts 8 to 10 inches in loose thickness and thoroughly compacted. All structural fill placed under load bearing areas should be compacted to at least 95 percent of the maximum dry density, as determined using test method ASTM D1557. The top of the compacted structural fill should extend outside all foundations and other structural improvements a minimum distance equal to the thickness of the fill placed beneath the footing. We recommend that compaction be tested periodically during placement of structural fill. Wet Weather Earthwork If construction is accomplished during wet weather, we recommend that structural fill consist of imported, clean, well-graded sand or sand and gravel. As mentioned previously, the on-site Page 5 of 13