3003 W CASINO RD BLDG 40-58 Geotech Report 2022-10-25

dry density,as determined by the modified Proctor test method,ASTM D 1557. The entire depth of fill at the project site should be compacted to 95 percent of the maximum dry density, in accordance with the procedure presented in Section 2-03.3(14)C, Method C for Compacting Earth Embankments of the Standard Specifications. Note that, if multiple fill sources are used for site filling, modified Proctor testing will be necessary for each fill type. We recommend that the thickness of each loose lift not exceed 8 to 10 inches, unless the contractor can demonstrate that adequate compaction is being achieved. In open areas,compaction of structural fill should be accomplished using a self-propelled vibratory roller. Backfill behind below-grade walls should also be compacted to 95 percent of its maximum dry density. Behind walls, extra care, thinner lifts, and smaller compaction equipment may be necessary to prevent damage to the walls or the development of excess lateral stresses in the wall. Geotechnical observation of fill placement and compaction(including field density measurements)should be provided throughout the full depth and plan extent of all filled areas. 3.5 TEMPORARY AND PERMANENT SLOPES Temporary unsupported slopes will be excavated to facilitate construction of the tunnels,utilidor, and other below-grade structures. Temporary slopes will also be present prior to wall construction along the east and west sides of the building. Actual slope configurations during construction and the maintenance of safe working conditions, including temporary excavation stability, should be the responsibility of the contractor, who is able to monitor the construction activities and has direct control over the means and methods of construction. All applicable local, state, and federal safety codes should be followed. All open cuts should be monitored by the contractor during and after excavation for any evidence of instability. If instability is detected, the contractor should flatten the side slopes or install temporary shoring. Temporary excavations in excess of 4 ft should be sloped in accordance with Safety Standards for Construction Work Part N,WAC 296-155-657,or shored. In the absence of groundwater seepage,the fill soils observed at the project site classify as Type C soils and should be inclined no steeper than 1'/2 H:1V (horizontal:vertical) according to WAC 296-155-657. Cuts into native till may be sloped at 1H:1V. Flatter slopes or temporary shoring may be required in areas where unstable slope conditions develop. Temporary excavation slopes should be protected by covering with plastic sheets or other means to prevent erosion. Permanent fill or cut slopes should be constructed no steeper than 2:1 (H:V). All permanent cut and fill slopes will need to be vegetated or otherwise protected to limit the potential for erosion as soon as practical after construction. Permanent slopes requiring immediate protection from the effects of erosion should be covered with either mulch or erosion control netting/blankets. Areas requiring permanent 5/16/14 P:\1423\002\O10\FileRm\R\Draft Bldg 40-58 Report\Bldg 40-58_draft rpt.docx INTERIM D RA F T 3-4