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� <br /> i <br /> R��ulmg�d cquipmcm un tlu• nauvc subgraJc wils during thc ���ct��r;athcr uionlhs �sill bc diliiaill and ihc <br /> � suhgrnde tt�ill likcly bccotnc hi�,hl�� dis�urbed antl rutted. In addiiior.a si6niticaut :mwunt uI mud r:m hc <br /> �>roduced L� ruuting :quipment JirecUy or ihe silts and d;rys in �vet �seather. Thereti�re, to ��rotec� thr <br /> siib�;rade snils and tu provide :ui adequatc working surl:�cc �i�r the contracWr's equipmem and labor, �ec <br /> _ rccummcnd lha� Ihc conlractor pratccl cspu�cd subrradc suils wilh sand :md gr�ccl, crushcd craccL i,r <br /> � A'1'B. <br /> , <br /> Permanent Cut and Fill S/opes <br /> I �Vc rccunnncuJ ILat pcnnauunt cid ur liil �lupcs bc consiructcd ai inclinaliuns uf 3F1:1 V or ilattcr. ;md bc II <br /> � blended inlo existing slopcs �vith smouth trausilions. 1'u achieve unifomi cun;paction. �vc recommend <br /> that fill slopcs bc slightly ovcrhuilt and cut back to cxpose wcll-compacicd till. � <br /> � "fo reduce erosion,ncwly consWctcd slopes should bc planied or hydroseeded shurily aftcr comple�ion of <br /> grading. Until the vegetalion is established, some sloughing and ravelling of tlre slopes should be <br /> � espected. This may uccessitate localized repnirs and reseeding. 'I'empomry covering,such as dean c�a�� <br /> plastic sheeling,jute fabric, or crosion conlrol blankels (such as Americau Gxcclsior Cwles 1 or Nonh <br /> Amcrican Gncn S I�U)cuuld bc uscJ tu prulcct Ihc slopcs duriug periods of raintall. <br /> � Utility TrencNes <br /> 'I'rench ercava�iun, pipe beddin��, and urnch backlilling should he completed using the general <br /> procedures dcsciihcd in Ihc 200G \1'SDO'I' St�mdard Spccificalions or u�hcr suil,���i� n��,��d����, si����r�d <br /> � hy the projeci civil enginecr. l'he silts and clays,gl�icial deposits,and fill soils encountered at the si�e are <br /> generally of low corrosivity based on ow esperience in the Puget Sound arca. <br /> � Uiility trench hackfill should consisl o1'struciural lill imd shoulJ be placcd in lifts o1'8 inche� or Ics* <br /> (loose thickness) such that adequale compaction can be achicved tliroughout tlic li1t. Sand backlill, <br /> ' conL•iining Iess ihau 5 percent fines,may be cumpacted in louse litis no� esceeding 12 inches when plaeeJ <br /> below five fect of t!ie finisheJ ground snrfxe. Gach IiR musl be cumpacted prior to placing lhc <br /> Isubscyucni li�i. 1'rio, to canp,,ctiou, thc backfill should Uc moiswre conditioncd to within 3 perccm nf <br /> � ILe eplimwn muisuuc coutent, if necessan. 71re backfill should hc compactcd in accordancc �eith thc <br /> crileria discus�ed above. I�igurc 4 illustr:ites reconunended trench compactim: criteri�i under p���ement <br /> Iaud non-swctural arcas. <br /> Sedimontatlon and Erosion Con[rol <br /> ! In our opinion, thc crosion potenlial of thc on•sitc soils is Imv to modcratc. Consuvction activitics <br /> � includiug stripping and grnding will expose soils to Ihe crosion elTects of wind and watec 11ie amount <br /> and potcutial impacts of crosiou are pmily related io the Iime of year that construction actoally occ�ns. <br /> t We��veather cons�niclion will increase the amou��l and exlent of erosion and poten�ial sedimentation. <br /> Ilirosion and sedimenlation conlrol mcasures m:q� Le implemeNed by i:;ing n cumbination o(interceptor <br /> s�vales, sliaw bale barriers, silt fcnces and straw mulcli lo�temporary erosiun protection of exposed soils. <br /> I All disturbed areas shoidd be tinish giad��d and secded as soon ns pncticable to reduce thc risk of crosiou. <br /> I:rosion ;�nd sedimeNution cuntrol mcastucs sliould be inslallcJ and main��iined in accurdance with thc <br /> rcquiramrnls ul ihu �'itp u(I�A�crcu- <br /> I <br /> f <br /> p,l;M1',; r,$)r�-UU"-nU Yn.4�'��� GEOENGINEER�' <br /> � Jalr I'_'Oi�b' <br /> , 53 <br />� � <br />