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Geotechnical Engineering Report 8 January 7,2020 <br /> QFC 852 Fuel Station,Everett, Washington RGI Project No.2019-258A <br /> Table 3 Structural Fill Compaction ASTM D1557 <br /> Minimum <br /> Location Material Type Compaction Moisture Content <br /> Range <br /> Percentage <br /> Foundations On-site granular or approved 95 +2 -2 <br /> imported fill soils <br /> Retaining Wall Backfill I On site granular or approved 92 +2 -2 <br /> imported fill soils <br /> Slab-on-grade On-site granular or approved 95 +2 -2 <br /> imported fill soils <br /> General Fill (non- On-site granular or approved <br /> structural areas) imported fill soils 90 +3 -2 <br /> Pavement, Subgrade On-site granular or approved <br /> and Base Course imported fill soils 95 +2 -2 <br /> Placement and compaction of structural fill should be observed by RGI. A representative <br /> number of in-place density tests should be performed as the fill is being placed to confirm <br /> that the recommended level of compaction is achieved. <br /> 5.3 UST EXCAVATION AND BACKFILL <br /> The installation of the USTs will require an excavation of up to 20 feet bgs. RGI does not <br /> expect that shoring will be needed for the excavation. <br /> However, if shoring has to be installed. Typically, contractor prefers slide rail shoring <br /> system for UST excavation. Slide rail shoring system is a dig-and-push style shoring <br /> system. With its modular flexible design, the system can work with a wide variety of <br /> shapes and sizes. The system is installed from the top down and removed from the <br /> bottom up, minimizing size of excavation, and soil disturbance. Based on the depth of <br /> excavation, they are designed as single, double, and triple track system. The double track <br /> system can provide protection at depth from 12 feet to 20 feet which is expected to be <br /> needed for the project. RGI recommends that double track slide rail system be used for <br /> the UST excavation support (if needed). <br /> The depth to the top of the USTs is typically 3 feet below finished grade with at least 2 <br /> feet of appropriate backfill material. The backfill can be either pea gravel or other <br /> material per API specifications for setting the tanks. <br /> The installation will require tank hold down slabs or anchors to accommodate possible <br /> buoyant forces. The UST system installation and design must be in accordance with API <br /> regulations. <br /> II I <br /> - <br /> RILEYGROUP <br />