10930 HOLLY DR Geotech Report 2025-08-08

.j: Helix Design Group,Inc.-Greenwood Heating&Air Conditioning,Everett,WA April 22,2022 Geotechnical Engineering Report Z0219 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 organic matter or debris, nor any individual particles greater than about 6 inches in diameter. Fill Placement: Clean sand, gravel,crushed rock, soil mixtures, and recycled materials should be placed in horizontal lifts not exceeding 8 inches in loose thickness, and each lift should be thoroughly compacted with a mechanical compactor. Compaction Criteria: Using the Modified Proctor test (ASTM:D-1557) as a standard, we recommend that structural fill used for various onsite applications be compacted to the following minimum densities: Fill Application Minimum Compaction Footing subgrade or bearing pad 95 percent Footing and stemwall backfill 90 percent Slab-on-grade floor subgrade(upper 2 feet) 95 percent Slab-on-grade floor subgrade(below 2 feet) 90 percent Asphaltic pavement base and subbase 95 percent Asphaltic pavement subgrade(upper 2 feet) 95 percent Asphaltic pavement subgrade(below 2 feet) 90 percent Subgrade Observation and Compaction Testing: Regardless of material or location,all structural fill should be placed over firm, unyielding subgrades prepared in accordance with the Site Preparation section of this report. The condition of all subgrades should be observed by geotechnical personnel before filling or construction begins. Also,fill soil compaction should be verified by means of in-place density tests performed during fill placement so that adequacy of soil compaction efforts may be evaluated as earthwork progresses. 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. For fill placement during wet-weather site work,we recommend using"clean"fill,which refers to soils that have a fines content of 5 percent or less(by weight)based on the soil fraction passing the U.S. No.4 Sieve. Migizi Group,Inc. Page 15 of 16 m,c;,x