2802 HOYT AVE EVERETT ELKS Geotech Report 2018-01-02 MF Import

Geotechnicai-Engineering Evaluation Everett Elks Club November 2. 2006 NGA File No. 751106 Page 8 in wet conditions, as compaction of a wet subgrade may result in further disturbance of the native soils. Instead, a layer of crushed rock or all-weather material may be placed over the prepared areas for protection from further disturbance. As mentioned earlier, the site soils are considered moisture sensitive and can disnirb when wet. We therefore recommend that construction take place in the summer during periods of extended dry weather, and suspended during periods of rainfall. If work is to take place during the wetter pan of the year, care should be taken during site preparation not to disturb the site soils. This can be accomplished by utilizing large excavators equipped with smooth buckets and wide tracks to complete earthwork, and diverting surface and groundwater now away from the prepared subgrades. Also, construction traffic should not be allowed on the exposed subgrade. A blanket of rock spalls should be used in construction access areas if wet conditions are prevalent. The thickness of this rock spall layer should be based on subgrade performance at the time of construction. For planning purposes, we recommend a minimum one -foot thick layer of rock spalls. Shoring Wall General: A shoring wall may be needed to retain the, southern, eastern, and northern sides of the excavation planned for the underground parking garage if the existing walls from the old structure cannot oring wail can be designed as a temporary system and the be incorporated into the new building. The sh building designed and constructed independent of the wall, or the shoring wall can be made permanent and integrated into the building design. In tiie latter case, the sharing wall would likely be designed to resist vertical loads as well as lateral loads. The most likely and feasible shoring system is a soldier pile wall. A soldier pile wall typically consists of a series of steel H-beams placed vertically at a uniform distance from one another (typically six to ten feet). The beams are usually placed in drilled shafts that are filled with concrete or grout. The concrete shafts are typically embedded below the bottom of the planned excavation a distance equal to one to two times the height of the cut to be shored. The steel beams are extended to above -finished ground surface to provide shoring capabi!ities for the cut. The beams are typically spanned by pressure treated timber or concrete panels. The H-beam sizes, shaft diameter, shaft embedment, and pile spacing are dependent on the nature of the soils anticipated in the cut and at depth, cut height, drainage conditions, and final geometry. NELSON GEOTECHNICAL ASSOCIA7ESLAC.