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� KA No.092-06160 <br /> Octobcr 25,2006 <br /> Page 5 <br /> Soil and groundwater conditions can be highly variable. Scheduling for soil work will need to be <br /> adjustable, to dcal with unanticipatcd conditions, so that the project can procecd smoothly and required <br /> deadlines can be met. If any variations or undesirable conditions are encountered durin� construction <br /> Krazan&Associates should be notified so that supplemental rccommendations can be made. <br /> Structursi Fill <br /> Bcst Management Practiccs (BMP's) should be followed when considering thc suilability of native <br /> glacial soils for use as structural fill. Thc nativc glacial soils l�ave variable fines (silt and clay) contcnts <br /> and are considered moisture sensitive. The native glacial soils may also have elevated natural moisture <br /> contents, and may need to be dried back during dry wartn wcather(typically durin�die summer months). <br /> Tl�e nativc glacial soils arc gener.:�.'y considered suitablc E'or rcusc as structural fill, provided the soil is <br /> relatively free of organic material and debris, and it is wilhiu � 2 percent of the optimum moisture <br /> content. If the native glacial soils are stockpiled S'or later use as structural fill, the stockpiles should bc <br /> covered to help protect the soil from wct wcathci• conditions. We recommend that a representative of <br /> ICrazan & Associates be on site during the excavation work to dctertnine which soils are suitable for <br /> stNctural fill. <br /> It should not be taken for granted that the onsitc solls may be used as the solc source for structural <br /> fill (especially during winter construction activities). Dur)ng wet weather conditions the soils wlth <br /> higher silt and clay contents will be moisture senstUve, easity disturbec! aud most likely ti�•ill nut <br /> meet campacttan :equirement�. Furthermore, during the winter the native suils typically have <br /> elevated n9tural molsturc contents, which wl:i Bmit t6e use of these materlels as strueturel fill <br /> wlthout proper mitigatton measures, The contractor should use Best n4anagement Practices to <br /> protect the soils during construction ,ctivitics and be familtar with wct weat6er anJ wintertime <br /> soit wark. An allowance for impo,r�ing structural 011 should be iucorporated into the constructioo <br /> cost of the project(for wintert(me construction t6(s may bc as high as 100 percent import). <br /> Importcd structural fill rnaterial sltould consist of well-gradcd gravcl or a sand and gravel mixture with a <br /> maximum grain six� oC 1'h inches and less than 5 percent fines (matcrial passing the U.S. Standard No. <br /> 200 Sieve). AlS structural fill material should be submitted for approval !o thc gcotechnical engineer at <br /> Icasl 48 hours prior to dclivery to the site. <br /> Pill soils should be placed in horizontal lifts not exceeding 8 inchcs loose thickness, moisture- <br /> conditioned as necessary (moisturc content of soil shall not vary by morc than t2 percent of optimum <br /> moisture), and the material should bc compactcd to at least 95 percent oCthc maximum dry dcnsity based <br /> on ASTM Test Method D1557. In placc density tests should be perfortned on all slruelural fill to verify <br /> proper moisture content and adequatc compaction. Additional lifts should not be placed if the previous <br /> lift did not meet the compaction requiremcnts or if soil condit.ions are not considcred stable. <br /> Kruan&As�ocietee,lne. �/� <br /> Oflices Serving The Wutcrn Unitcd Statcs / <br /> � <br />