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SunwoodDriveΑStreetImprovements <br />Ramsey,Minnesota <br />NTIProjectNo.16.61770.100 <br />UTILITYLINECONSTRUCTION <br />Thenativesandsoilsobservedinsoilboringsweregenerallysuitableforutilitysupportandutility <br />backfill.Duetotheencounteredgroundwaterlevelsanddependingontheinstallationdepthofthe <br />utilities,temporarydewateringmayberequiredduringtheutilitytrenchexcavations.Stabilizationof <br />thetrenchsubgrademayberequiredinordertoprovideastableplatformforconstruction. <br />Stabilizationcouldconsistofaonehalftoonefootlayerofcrushedrockorsandwithamaximum5 <br />percentmaterialpassingtheNo.200sieveand50percentpassingtheNo.40sieve. <br />Recordortheirdesignatedrepresentativeshouldobservetheproject <br />TheGeotechnicalEngineerof <br />excavationstodeterminethatunsuitablematerialshavebeenproperlyremovedandadequatebearing <br />supportisprovidedbytheexposedsoils.Theexposedsoilatthebaseshouldbecompactedtonoless <br />than95percentstandardProctormaximumdrydensity(ASTMD698).Suchobservationsandtesting <br />shouldbeperformedpriortobackfilling. <br />Theonsitenonorganicsoilsareanticipatedtobesuitableforreuseifproperlymoistureconditioned <br />andcompacted.Replacementbackfillrequiredinutilitytrenchesshouldconsistofnonorganicmaterial <br />similartothesurroundingsoil.AllimportfillshouldbeapprovedbyNTIorthe/źƷǤ͸ƭrepresentative. <br />Itisespeciallyimportantthattrenchbackfillforutilityconstructionwithinpavedareasbethoroughly <br />compactedtominimizefuturepavementdamage.Werecommendthatsuchsoilsbecompactedin <br />accordancewiththerecommendationsnotedintheͻtƌğĭĻƒĻƓƷandCompactionofEngineeredCźƌƌͼ <br />sectioninAppendixBofthisreport. <br />Thestabilityofembankmentsalongutilityexcavationsisdependentonsoilstrength,sitegeometry, <br />moisturecontent,andanysurchargeloadforexcavatedsoilsandequipment.Wepresentcautionary <br />remarksconcerningstabilityofexcavationsideslopesintheͻ9ǣĭğǝğƷźƚƓ{ƷğĬźƌźƷǤͼsectionofthisreport. <br />TheContractorissolelyresponsibleforassessingthestabilityofandexecutingundergroundutilityand <br />projectexcavationsusingsafemethods.ThecontractorisalsoresponsiblefornamingtheͻĭƚƒƦĻƷĻƓƷ <br />źƓķźǝźķǒğƌͼasperSubpartPof29CFR1926.6(FederalRegisterOSHA). <br />TheGeotechnicalEngineerofRecordortheirdesignatedrepresentativeshouldobservetheproject <br />excavationstodeterminethatconditionsaresimilartothoseencounteredintheborings,andthat <br />adequatebearingsupportisprovidedbytheexposedsoils. <br />ExcavationStability <br />Excavationdepthandsidewallinclinationshouldnotexceedthosespecifiedinlocal,stateorfederal <br />regulations.Excavationsmayneedtobewidenedandsloped,ortemporarilybraced,tomaintainor <br />developasafeworkenvironment.Contractorsmustcomplywithlocal,state,andfederalsafety <br />regulationsincludingcurrentOSHAexcavationandtrenchsafetystandards.Temporaryshoringmustbe <br />designedinaccordancewithapplicableregulatoryrequirements. <br />Excavationsthatpenetratethegroundwatersurfacewillrequiredewateringwithsandpointsorwells. <br />Werecommendthatthegroundwatersurfacebemaintainedaminimumof2feetbelowthebottomof <br />theexposedexcavation. <br />Page4of7 <br /> <br />