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

i Subsurface ExpbrWion, Geologic Hawrd. and l Sno-lslt Skills Center Addirion PreUminary Geotechnical Engineering Report Prelimi Desi n Recommendations Everett, Washin ton I III. PRELIMINARY DESIGN RECOD�tENDATIONS i � 8.O INTRODUCTION � I It is our opinion that from a geotechnical standpoint the site is suitable for the proposed I improvements provided that the recommendations contained herein aze properly followed. � I Medium dense to very dense lodgement till was encountered at relatively shallow depths in our I explorations on the site, and conventional spread footings may be used for support of the praposed new buildings. Some overexcavation and replacement of fill soils should be expected 'i � if it is encountered below building foundations, floor slab azeas, or new pazking and/or access azeas. Standazd pavement sections should perform well within the proposed new pazkin8 and bus loading azeas with proper subgrade prepazation. The existing fill and lodgemem till soils I contain substantial quantities of silt, and during the wet winter and spring months, the contractor and school district should be prepazed to manage over-optimum moisture content (wet) soil and subgrade conditions. Construct9on should be timed to take advantage of dry Iweather, if possible. I9.0 SITE PREPARATION � Site preparation of azeas to be graded should include removal of all uees, brush, any demolition debris from existing suuctures, and any other deleterious material. Additionally, the upper organic topsoil should be removed and the remaining roots 8rubbed. Based on our I explorations, the majority of the topsoil had been stripped as part of original grading activities. � If topsoil is present, it is ezpected t6at it will be between 6 and 12 inches thick. f Areas where loose soils exist due to previous grading, filling, or grubbing operations should be I considered as uncontrolled fill to the depth of disturbance and ueated as subsequently recommended for structural fil1 placement. Where existing, loose fill or natural sediments aze I relatively free of organics and neaz their optimum muistuTe content for compaction, they can be segregated for reuse as structural fill. Since the densiry of the soil is vaziable, random soft I pockets tnay exist, and the depch and extent of suipping can best be determined in the field by the geotecLnical engineer or engineering geologist. � 9 1 Permanent Cut and Fill Slopes permanent cut and suuctural fill slopes that aze not intended to be exposed to standing water �� should be graded no steeper than 2H:1V (Horizontal:Vertical). Pern�anent cut and swctural fill slopes that will be exposed to standing water should be inclined at 3H:IV or flatter. Slopes should be hydroseeded, landscaped, or otherwise protected as soon as possible afta gradinB• I Cut slopes in natural soils that must be steeper than 2H:1V should be prot�by a rockery or ASSOCIATFl)E1RTH SCIF,NCES, INC. (,'I� lune II, 2008 Page 10 `J � EG/Id-EFAb�1I3A5-ProjsttslN10.401131EEIwP ,