1502 WALL ST IMAGINE CHILDRENS MUSEUM Geotech Report 2022-10-25

Imagine Children's Museum Building Addition Revised Geotechnical Engineering Report Everett, Washington Design Recommendations Spread footings may be used for building support when founded entirely on undisturbed lodgement till utilizing an allowable bearing pressure of 8,000 psf, including both dead and live loads. This bearing pressure assumes all footings will be founded directly on undisturbed, very dense, native lodgement till. An increase of one-third may be used for short-term wind or seismic loading. Perimeter footings should be buried at least 18 inches into the surrounding soil for frost protection; interior footings require only 12 inches burial. However, all footings must penetrate to the prescribed bearing strata, and no footing should be founded in or above loose, organic, or existing or new fill soils. To limit settlements, all footings should have a minimum width of 18 inches. It should be noted that the area bounded by lines extending downward at 1H:1V from any footing must not intersect another footing or intersect a filled area that has not been compacted to at least 95 percent of ASTM D 1557. In addition, a 1.5H:1V line extending down from any footing must not daylight because sloughing or raveling may eventually undermine the footing. Thus, footings should not be placed near the edge of steps or cuts in the bearing soils. Anticipated settlement of footings founded on lodgement till or approved structural fill should be on the order of 3/4 inch or less. However, disturbed soil not removed from footing excavations prior to footing placement could result in increased settlement. All footing areas should be inspected by AESI prior to placing concrete to verify that the design bearing capacity of the soils has been attained and that construction conforms to the recommendations contained in this report. Such inspections may be required by the governing municipality. Perimeter footing drains should be provided, as discussed under the "Drainage Considerations" section of this report. In our opinion, the subsurface conditions at the site are consistent with seismic Site Class "C" in accordance with the 2015 International Building Code (IBC), and the publication American Society for Civil Engineers (ASCE) 7 referenced therein, the most recent version of which is ASCE 7-10. 8.1 Existing Adjacent Foundations Where new foundations will be constructed adjacent to existing foundations, the foundations should be constructed in such a manner that surcharges and undermining are avoided, if possible. The support zone for existing foundations should be considered to be defined by a line projected downward and away from existing foundation elements at an inclination of 1H:1V. Excavation within the support zone of existing foundations should be avoided. If it is necessary to excavate within the support zone for an existing foundation, it will be necessary to provide underpinning in the form of pin piles or some similar system prior to excavation. We should be allowed to provide situation-specific recommendations if underpinning is needed. March 28,2019;Revised April 16,2019 ASSOCIATED EARTH SCIENCES,IN J SGB/Id-190104E001-3-Projects\20190104\KE\WP Cage /S/�