3535 RIVERFRONT BLVD Geotech Report 2023-02-22

September 24, 2018 HWA Project No. 2015-061-21 and/or improper moisture content. Soils with high fines contents are particularly susceptible to becoming too wet, and coarse-grained materials easily become too dry, for proper compaction. 4.9.3 Wet Weather Earthwork General recommendations relative to earthwork performed in wet weather or in wet conditions are presented below. These recommendations should be incorporated into the contract specifications. • Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation of unsuitable and/or softened soil should be followed promptly by placement and compaction of clean structural fill. The size and type of construction equipment used may need to be limited to prevent soil disturbance. Under some circumstances, it may be necessary to excavate soils with a backhoe to minimize subgrade disturbance caused by equipment traffic. • For wet weather conditions, the allowable fines content of the structural fill should be reduced to no more than 5 percent by weight of the portion of the fill material passing the 3/4-inch sieve. The fines should be non-plastic. It should be noted this is an additional restriction on the structural fill materials specified. • The ground surface within the construction area should be graded to promote surface water run-off and to prevent ponding. • Within the construction area, the ground surface should be sealed on completion of each shift by a smooth drum vibratory roller, or equivalent, and under no circumstances should soil be left uncompacted and exposed to moisture infiltration. • Bales of straw and/or geotextile silt fences should be strategically located to control erosion and the movement of soil. 4.9.4 Temporary Excavations Maintenance of safe working conditions, including temporary excavation stability, is the responsibility of the contractor. In accordance with Part N of Washington Administrative Code (WAC) 296-155, latest revisions, all temporary cuts in excess of 4 feet in height must be either sloped or shored prior to entry by personnel. The existing near surface fill and alluvial soils are generally classified as Type C soils per WAC 296-155. Where shoring is not used, temporary cuts in Type C soils should be sloped no steeper than 1'/2H:1 V (horizontal:vertical). 5. CONDITIONS AND LIMITATIONS We have prepared this Geotechnical Engineering report for Shelter Holdings and the MacLeod IReckord Engineering team for use in design of portions of this project. This report should be provided in its entirety to prospective contractors for bidding and estimating purposes; however, Final Geotechnical Report-3-Acre Park.docx 27 HWA GeoSciences Inc.