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Decembcr 15. 1992 10 923-1184 <br />5.5 Garthwork - Cxcavation of Unsuitable Soils <br />5.5.1 Gencral <br />Depending an Ihe overall economics of lhe earlhtvork and piles, lhe unsuilable soils may be <br />excavated from porlions or all of Uie sile. 7'he general proceJure tvill be lo rxcavate and <br />slockpile the existing fills and then excavale and remove from Ihe sile the peals. Any debris <br />ar very sofl/�vet matcrials encountered in the fill should also be removed fmm lhe site. In <br />wel tvcalher the excavaled (ills may also have lo bc removed from Ihe silc. Due to Ihe sofl, <br />unslablc nature of the pcat combined with potenlial groundwater seepa�e, a large backhoe <br />will proUably bc required lo excavalc lhc pcals. <br />All new fills should meet Ihe crileria specified in Seclion 5.5.3. <br />5.G Garthwork - Non-removal of UnsuitaLles <br />In arcas. where the exisling loosc fills and peal arc nal removed, we recommend lhe <br />follotving: <br />A. In amas tvhere Ihe reise-in-grade is Icss lhan two fcet, lhe ground should be proof- <br />rolled tvilh any soft, unslable arcas over-excavaled to provide a siablc base. <br />U. Gslablish rough final grades as soon as possiblc (a minimum of onc month prior <br />placing ulilitics and lwo monlhs prior to paving) lo and prior lo installing ulililies and <br />piles. 1f lhese mininwm prcload periods can not bc incet, lhan all arcas undcrlain by <br />peal should bc surcharged wilh al Icasl Itvo fcel of fill and Ihc arcas wilh an excess of <br />4 feet of peal should bc surchar�ed tvilh G fccl of filL _ <br />C. In areas tvhem the Ihickness of peat exceeds 4 feel, place a surcharge fill of Uiree (eet <br />for a minimum perioJ af one monlh regardless of lhe prcload period. 7'his tvill <br />consist of raising the �rade lo Ihree feet above the final grade (pavement, landscape, <br />or widcrsl�b elevalion) for one monih. <br />D. It is eslimated Ihal during thc surchargc/prcload periuds, Ihe total sclUemenls will be <br />on the order of 2 lo four inches. Gven wilh preloading and surcharging, some IimileJ <br />di(fcrenlial movemenl should bc expecled bclwcen thc pilasupporled slruclures and <br />U�c adjacenl ground surfarc. Il is eslimaled that over lhc lon� tenn, lhis diffcrential <br />setUcment will bc behvicen about onc to hvo inches. <br />G The achial seulement of Ihe surcharge areas sl�ould be monitored with a serie:� o. <br />selllemenl platforms placed on lhe exisling ground prior to fill placement. The <br />plalfonn; should Uc ��laced on aboul a 100 (ool spacing and survcycd weekly aflcr fill <br />��laccnunl or until tl�c setllemenl is :ony�leted. Thc setlletnenl plal(orm dala tvill be <br />uscd lo evalualc when lhc surcharge can bc retnoved. <br />Golder As:ociates <br />