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 Preload Extent: The crest of the new preload should extend a minimum of 25 feet horizontally outside of the building lines where new preload is placed. Preload Duration & Monitoring: We expect anticipated settlement will occur in about 3 to 6 months, however, actual settlement times may vary. The preload should be monitored to determine the magnitude and rate of settlement. The data will be used to determine whether the consolidation of the underlying soils has slowed sufficiently to allow removal of the preload. In order to provide uniform support and settlement across the building area,the preload should not be removed until this has occurred. We recommend using five settlement plates,one in the centerline of the new preload and near each corner. The corner plates should be located at least 25 feet inside of the structure. A detail of a typical plate is attached. The elevations of the plates should be surveyed every other day during ' filling and once a week thereafter until the surcharge is removed. If a rod is bent by construction equipment,it should be straightened and resurveyed as soon as possible. The rod elevations should be referenced to a benchmark located well outside the influence of the site fill,roughly 200 feet from the embankment. The settlement data should be provided to us immediately after the readings are taken so that we may review and comment as appropriate. 4_3 Spread Footings In our opinion, conventional spread footings can be used to support the new prefabricated metal service building structure if the subgrades are properly prepared. Footing Depths and Widths: For frost and erosion protection, the bases of all exterior footings should bear at least 18 inches below adjacent outside grades,whereas the bases of interior footings need bear only 12 inches below the surrounding slab surface level. To reduce post-construction settlements, continuous (wall) and isolated (column) footings should be at least 18 and 24 inches ' wide, respectively. Bearing Subgrades: Structural fill bearing pads, a minimum of 2 feet thick and compacted to a densityof at least 95percent(based on ASTM:D-1557),should underlie spread footings on the site. P g If foundation construction occurs during wet conditions,it is possible that a geotextile fabric,placed between the bearing pad and native soils, will be necessary. Lateral Overexcavations: Because foundation stresses are transferred outward as well as ' downward into the bearing soils,all structural fill placed under footings,should extend horizontally outward from the edge of each footing. This horizontal distance should be equal to the depth of placed fill. Therefore,placed fill that extends 24 inches below the footing base should also extend 24 inches outward from the footing edges. Subgrade Observation: All footing subgrades should consist of firm, unyielding, native soils, or ' structural fill materials that have been compacted to a density of at least 95 percent (based on ASTM:D-1557). Footings should never be cast atop loose, soft, or frozen soil, slough, debris, existing uncontrolled fill, or surfaces covered by standing water. Migizi Group, Inc. Page 10 of 17 .