2410 RAILWAY AVE Geotech Report 2023-04-06

Penske Truck Leasing-Proposed Service Facility,2410 Railway Ave, Everett,WA Mar.8,2019/Rev.Feb. 25,2020 Geotechnical Engineering Report P1493-T18 • Floor Options: We recommend that floor slabs be reinforced and supported on properly compacted structural fill as a floor subbase. All subbase fill should be compacted to a density of at least 95 percent (based on ASTM:D-1557). The floor slabs may also be pile supported. Recommendations for slab-on-grade floors are provided in Section 4.5. • Preload Fill: We recommend that the new building pad be constructed and preloaded with an additional 5 feet of preload fill placed over the building area to induce settlement prior to construction. The new preload areas should extend at least 25 feet beyond the proposed building walls. A minimum preload thickness of 5 feet should be placed. We recommend that this preload remain in place for a period of 3 to 6 months prior to construction. When preloading is completed, this fill should then be placed to raise grades in the remaining areas of the site. • Preload Alternatives: If preloading is not feasible due to time constraints,provision should be made to relevel the pre-engineered metal building as settlement occurs. If this is not feasible or deemed unacceptable, the building can be supported on augercast piles. Recommendations for augercast piles are presented in Section 4.4. • Pavement Sections: After removal of any organics underlying pavements, we recommend a conventional pavement section comprised of an asphalt concrete pavement over a crushed rock base course over a properly prepared (compacted) subgrade or a granular subbase. All soil subgrades should be thoroughly compacted,then proof-rolled with a loaded dump truck or heavy compactor. Any localized zones of yielding subgrade disclosed during this proof-rolling operation should be overexcavated to a depth of 12 inches and replaced with a suitable structural fill material. • Settlement: We anticipate that the new fill and preload will induce approximately 3 inches of settlement over the building area during a 3 to 6 month preload period. The preload will serve to densify the underlying soils and reduce liquefaction settlements. However,post construction settlement on the order of 1 inch should be expected under the new development. This settlement is due primarily to the poor quality of fill material which underlies the site and the presence of compressible soils beneath the fill. We recommend that all structures be designed to accept static settlements and to accommodate seismic settlements without catastrophic collapse. The following sections of this report present our specific geotechnical conclusions and recommendations concerning site preparation, spread footings, slab-on-grade floors, asphalt ' pavement, and structural fill. The Washington State Department of Transportation (WSDOT) Standard Specifications and Standard Plans cited herein refer to WSDOT publications M41-10, Standard Specifications for Road, Bridge, and Municipal Construction, and M21-01, Standard Plans for Road, Bridge, and Municipal Construction, respectively. Migizi Group, Inc. Page 7 of 17