9001 AIRPORT RD SNO ISLE SKILL CTR EXPANSION 2009 Geotech Report 2018-01-02 MF Import

i � S+�surjace Espbration. Geologic Hazard, and SYw-Isle Skills Center AddiNon Prtlimiwary Geotechnicd Engintering Report Everen Washingron Preliminary DesiRn Recomrnerulntions Ifluid of 50 pcf. If pazking azeas are adjacent to walls, a surcharge equivalent to 2 feet of soil should be added to the wall height in determining lateral design forces. ! As required by the 2006 IBC, retaining wall design should include a seismic surcharge I pressure in addition to the equivalent fluid pressures presented above. Coasidering the site soils and t6e recommended wall bac�ll materials, we recommend a seismic surchazge pressure of 12H, where H is the wall height in feet. The seismic surcharge should be modeled ias a rectangulaz distribution with the resultant applied at the midpoint of the wall. 'I'he lateral pressures presented above are based on the conditions of a uniform backfill I consisting of on-site glacial soils or imported soils compacted to 90 percent of ASTM:D 1557. A higher degree of compacdon is not recommended, as this will increase the pressure acting on the wall. A lower compaction may result in settlement. Thus, the compaction level is criticai � and must be tested by our firm during placement. Surchazges from adjacent footings, 6eary construction equipment, or sloping ground must be added to the above values. Footing and wall drains should be provided for all retaining walis, as discassed under the "Drainage IConsiderations" section of this report. Figure 3 shows a conceptual rendering of typical retaining walls. ( 15.1 Passive Resistance and Friction Factors S Lateral loads can be resisted by friction between the foundation and native till or supporting � swctural fill soils, or by passive earth pressure acting on the buried portions of the foundations. We recommend the following design parameters: 1 • Passive equivalent fluid = 350 pcf • Coefficient of friction = 035 � The above values aze allowable and include a safety factor of 1.5. � 16.0 FEASIBILITY OF ON-SITE INFILTRATION ILaboratory testing of the near-surface soils (copies of which aze in the Appendix of this report) indicated elevated silt contents that would impede infiltration of storm water. Based on the I relative densiry and the silty soils encountered in our explorations, convemional infiluation , systems are not recommended for this site. I I June 11, 2008 ASSOC/ATED F.1RTN SCIENCES, INC. IEG/W-EEQB0113A5-Projedsl2POd02i31EE1WP Page 18 U ',