2514 RAINIER AVE Geotech Report 2022-10-25

'4\ amec foster 1 wheeler "pit-run"), and mixtures of silt, sand, and gravel. Soils used for structural fill should not contain any I organic matter or debris, or any individual particles greater than approximately 6 inches in diameter, and should have no more than 40 percent fines (silt and clay that passes the U.S. No. 200 sieve). Fill Placement: Structural fill should be placed in horizontal lifts not exceeding 8 inches in loose thickness, and each lift should be thoroughly compacted with a mechanical vibratory compactor. I Other procedures may be appropriate for some materials. Compaction Criteria: Using the Modified Proctor test (ASTM D1557) as the standard, we recommend , structural fill be used for various on-site applications and compacted to the following minimum densities: , Fill Application Minimum Compaction Footing subgrade 95 percent Footing and stemwall backfill 90 percent Slab-on-grade floor subgrade 90 percent Retaining wall subgrade 95 percent Retaining wall backfill 90 percent Asphalt pavement subgrade 95 percent ' Walkway pavement subgrade 90 percent Utility trench backfill under pavements/structures 95 percent Utility trench backfill in non-paved areas 90 percent Athletic field subgrade 90 percent 1 Subgrade Verification and Compaction Testing: Regardless of material or location, all structural fill should be placed over dense, unyielding subgrades. The condition of all subgrades should be verified by an Amec Foster Wheeler representative before filling or construction begins. In addition, fill soil compaction should be verified by means of in-place density tests performed during fill placement so the adequacy of the soil compaction efforts may be evaluated as earthwork progresses. 1 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 (the 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. For fill placement during wet-weather site work, we recommend using I Amec Foster Wheeler 20 Project No.6-917-18116-0 \\Sea-fs1\WordProc\ Projects\18000s\18116 Everett School District\Geotech Report\Revised\2017_10-19_Everett Middle School Geotech_Sx.docx