2825 COLBY AVE COLBY CENTER Geotech Report 2018-01-02 MF Import

GEOTECHNICAL ENGINEERING STUDY Mr. Arthur Skotdal _, c/o Dykeman Architects F-6225 July 27, 1993 Page 4 DISCUSSION AND RECOMMENDATIONS -- General Based on the results of our study, it is our opinion that the site soils wiil adequately — support the proposed building utilizing conventional foundations with moderately high soil bearing values. The most critical geotechnical aspects of the planned development will be completing the proposed excavation with out destabilizing the adjacent streets and -- First Interstate Bank building. It is our understanding that approximately twelve (12) feet of space adjacent to Colby and Hewitt Avenues will be available for the proposed cut. Sufficient room is available to slope back th�east side of the excavati�n. Given ti oe dense ' consistency of site soils, it appears that there will be sufficient room to utilize temporary slope cuts up to a maximum inclination of 3I4H:1 V (Horizontal:Vertical) based on OSHA guidelines. Per WISHA code, steeper cut slopes could be utilized, as discussed in the j Excavation and Slope section of this report. If removal of the existing side walk is not an ' option, temporary shoring will be required, The shoring, if necessary, should consist of a combination of cantilevered soldier pile walis with lagging, or soldier piles with tie-backs � and lag��ng depending upon the depth of the excavations. ECI would be available to provide detailed shoring recommendations once the proposed excavation plan is available. I We also understand the foundation depth of the First Interstate Bank building is such that underpinning or shoring will not be required on the north side of the excavation. Slab-on-grade floors can be supported on the dense native soils exposed at the excavation base. ITo attain the subgrade elevation for the street level parking proposed for the east site of I the site, the existing basement will require filling. The native silty sand soil was near its optimum moisture content during our exploration and would be suitable for structural fill. Prior to fillinp, the concrete basement slab should be broken up to prevent the build-up of y groundwater and softening of the overlying structurai fill. I These and other geotechnical aspects of the proposed development are discussed in more Idetail in the following sections of this study. � IEarth Consultants, Inc.