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SunwoodDriveΑStreetImprovements <br />Ramsey,Minnesota <br />NTIProjectNo.16.61770.100 <br />EngineeredFillandWinterConstruction <br />Thesiltysandsoilsonthissitewillbesusceptibletofrostactionifnotprovidedadequatedrainage, <br />insulationorcoverage.Frozensoilshouldnotbeusedasbackfill.Whentheambientairtemperature <br />fallsbelowfreezingforanextendedperiodoftime,frostforms,andsoilnearthesurfacegradeexpands. <br />Settlementofthefillmayoccurasthefrozensoilsthaw. <br />Iffrostpenetratesthesoilpriortopaving,soilsmustbethawed,scarified,andrecompactedas <br />recommendedinthisreport.Subgradesoilsshouldbeinspectedpriortopavingtoverifyfrozen <br />conditionsarenotpresent. <br />PAVEMENTRECOMMENDATIONS <br />MillandOverlayRecommendations <br />Considerationcouldbemadetomillingandoverlayingtheexistingpavement.Theroadwaysections <br />appeartohaveasufficientlythickinplacepavementsection,overamajorityoftheprojectalignment, <br />whichwouldlenditselftorehabilitationviamillandoverlaytechniques. <br />Ingeneral,pavementsectionsconsistingof3inchesorlessofbituminousasphaltcanbedifficultto <br />effectivelymillandoverlayasoftentimestheentirepavementsectionisreclaimedduringthe <br />attemptedpartialsectionmillingprocess.Additionally,inlocationswheretheexistingpavement <br />thicknessislessthantherecommendedthickness,amillandoverlaywouldnotberecommendedunless <br />astructuraloverlaywereappliedtoincreasetheoverallthickness. <br />PavementReconstruction <br />Ifthepavementsectionistoberemovedandreplacedinitsentirety,themostconservativemethodof <br />subgradepreparationwouldberemovetheundocumentedfillsoilsandreplacethemintheirentirety <br />withproperlycompactedengineeredfill.Thismethodofsubgradepreparationwouldprovidethemost <br />uniformsubgradebutwouldalsobethemostcostlymethodofconstructionandwouldberelativelya <br />typicalmethodofsubgradepreparationforimprovementstoexistingmunicipalroadways. <br />IftheCityiswillingtoacceptsomeriskinpotentiallongtermdetrimentalperformanceforthe <br />significantupfrontsavings,theroadwaycanbereconstructedovertheexistingfill.NTIrecommends <br />thatpriortoinstallingtheaggregatebase,theexistingsubgradeshouldbescarifiedandrecompacted <br />toadepthofatleast12inches.Aproofrolltestshouldthenbeperformedtodeterminesoftor <br />unstablesubgradeareas.Theproofrollshouldbeperformedwithatandemaxledumptruckloadedto <br />grosscapacity(atleast20tons).Acceptancecriteriaoftheproofrollshallbelimitedtorutformationno <br />morethanoneinchdepth(frontorrearaxles)andnopumping(rolling)observedduringthevisual <br />inspection.Proofrolltestsshouldbeobservedbyanexperiencedtechnicianorgeotechnicalengineer <br />priortoplacementoftheaggregatebasecoursetoverifythesubgradewillprovideadequatepavement <br />support. <br />Ifruttingorlocalizedunstablesubgradeareasareobserved,thoseareasshouldbesubcut,moisture <br />conditioned,andrecompactedorremovedtoastabledepth. <br />Page5of7 <br /> <br />