Safety Manual

BWC’s Division of Safety & Hygiene

Excavationfor

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Table of ContentsChapter Subject PageNo. Introduction 31 Beforebeginningthejob 4� Cave-insandprotectivesupportsystems 93 Slopingandbenching 1�4 Othersafetyconsiderations 135 Soilmechanics 156 Materialsandequipment 187 Fallsandexposuretofallingloads �08 Heat-andcold-relatedillnessesandtreatments �19 Lockout/tagout �410 Hazardousatmospheresandconfinedspaces �511 Personalprotectiveequipment �91� Lasers(non-ionizingradiation) 3013 Trafficcontrolandfleetsafety 3114 Siteassessmentquestions 3�15 Glossary 34

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TheOhioBureauofWorkers’Compensation’s(BWC)DivisionofSafety&Hygienehasdevelopedthisindustry-specificpublicationtofocusonsafetyandhealthissuesinthetrenchingandexcavationindustry.Whilethispublicationisnotall-inclusive,itattemptstoatleasthighlightmanycommoncausesofinjuriesthatoccuronthejob.

BWCrealizesthatcompanieswithinthetrenchingandexcavationindustryhaveindividualneedsandthatnotalltheinformationpresentedhereispertinenttoev-eryemployer.Butbyimprovingsafetyandpreventingaccidents,youcanprotectyourworkforcewhileatthesametimereduceyourworkers’compensationcosts.

Safetyisn’ttheonlythingyoucandotoreducethiscost.Youcanalsoloweryourpremiumsbyproactivelymanagingyourworkers’compensationclaims.Thisincludesinvestigation,earlyreportingofinjuriesandworkingwithyouremployerservicesspecialistandclaimsservicespecialist.

BWC’sgoalistohelpcompanieseliminateincidentsandinjurieswhilereducingworkers’compensationexpenses.Thecombinationofproactivesafetystrategiesoutlinedinthismanualandahands-onclaimsmanagementwillhelpyoureduceinjuriesandlowercosts.

YoualsocanlearnmoreaboutothersafetyservicesofferedbyBWCbyvisitingohiobwc.comorcalling1-800-OHIOBWCtorequestaSafety Services Catalog.

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Chapter1Beforebeginningthejob

Anexcavationisanyman-madecut,cavity,trenchordepressionintheearth’ssurfaceformedbyearthremoval.Thiscanincludeanythingfromcellarstohigh-ways.TheOccupationalSafetyandHealthAdministration’s(OSHA’s)standard(�9CFR19�6subpartP)coversallopenexcavations,includingtrenches,wherethedepthisgreaterthanthewidthandthewidthatthebottomdoesnotexceed15feet.

Manyon-the-jobincidentsresultfromincompleteplanning.Ifyouarecorrectingmistakesafterworkhasbegun,itslowsdownthejob,addscostsandincreasesthepossibilityofanexcavationfailure.Ifyou’reacontractor,youneedtobuildsafetyintothepre-bidplanninginthesamewayyouconsiderallotherpre-bidfactors.Developsafetychecklistsbeforepreparingabidtomakecertainthereisadequateinformationaboutthejobsiteandallneededitemsareonhand.MakesurethesechecklistsincorporateelementsofrelevantOSHAstandardsandotherinformationnecessaryforsafeoperations.

Beforepreparingabid,takethesespecificsiteconditionsintoaccount:■ Traffic;■ Nearnessofstructuresandtheirconditions;■ Soil;■ Surfaceandgroundwater;■ Thewatertable;■ Overheadandundergroundutilities;■ Weather.

Usejob-sitestudies,observationsandtestboringsforsoiltypeorconditionsandconsultationswithlocalofficialsandutilitycompaniestodeterminethesiteconditions.Beforeanyexcavationbegins,locateutilityinstallations—sewer,telephone,fuel,electric,waterlinesoranyotherundergroundinstallations—thatyoumayencounterduringdigging.Also,contacttheutilitycompaniesorownersinvolvedandinformthem,withinestablishedorcustomarylocalresponsetimes,oftheproposedwork.Asktheutilitycompaniesorownerstofindtheexactlocationoftheundergroundinstallations.Iftheycannotrespondwithin�4hours—unlesstheperiodrequiredbystateorlocallawislonger—oriftheycannotfindtheexactlocationoftheutilityinstallations,proceedwithcaution.Tofindtheexactlocationofundergroundinstallations,usesafeandacceptablemeans.Ifundergroundinstallationsareexposed,OSHAregulationsalsorequirethattheyberemoved,protectedorproperlysupported.

Whenallthenecessaryspecificinformationaboutthejobsiteisassembled,determinetheamount,typeandcostofthesafetyequipmentneeded.Makeanin-ventoryofthesafetyitemsonhandbeforedecidingwhatadditionalsafetymate-rialmustbeacquired.Nomatterhowmanytrenching,shoringandbackfillingjobshavebeendoneinthepast,approacheachjoblikeitisyourfirst,withtheutmostcareandpreparation.

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Itisimportant,beforebeginningthejob,toestablishandmaintainasafetyandhealthprogramfortheworksitethatprovidesadequatesystematicpolicies,proceduresandpracticestoprotectemployeesandallowthemtorecognizejob-relatedsafetyandhealthhazards.

Aneffectiveprogramincludesprovisionsforthesystematicidentification,evalu-ationandpreventionorcontrolofgeneralwork-placehazards,specificjobhaz-ardsandpotentialhazardsthatmayarisefromforeseeableconditions.Writetheprogramtoreflecttheuniquecharacteristicsofthejobsite.

Toensurethatsafetypoliciesareimplementedeffectively,supervisors,employeegroupsincludingunions,andindividualemployeesmustcooperate.Eachsupervi-sormustunderstandthedegreeofresponsibilityandauthorityheorsheholdsinaparticulararea.Foreffectivelaborsupport,notifyaffectedunionsofconstructionplansandaskfortheircooperation.

Italsoisimportanttoprovideemployeesthatareexposedtopublicvehiculartraf-ficwithwarningvestsorothersuitablegarmentsmarkedwithormadeofreflec-tiveorhigh-visibilitymaterial.Ensurethatemployeesweartheirvests.Instructworkerstoremoveorneutralizesurfaceencumbrancesthatmaycreateahazard.

Inaddition,ensurethatnoemployeeoperatesapieceofequipmentwithoutfirstbeingproperlytrainedtohandleitandfullyalertedtoitspotentialhazards.

Incorporateproceduresforfastnotificationandinvestigationofaccidentsinthetrainingandsite-safetyandhealthprogram.

CompetentpersonThedesignatedcompetentpersonshouldhavetraining,experienceandknowl-edgeofthefollowing:■ Soilanalysis;■ Useofprotectivesystems;■ Requirementsof�9CFRPart19�6SubpartP.

Abilitytodetect:■ Conditionsthatcouldresultincave-ins;■ Failuresinprotectivesystems;■ Hazardousatmospheres;■ Otherhazards,includingthoseassociatedwithconfinedspaces;■ Existingandpredictablehazards,andauthoritytotakepromptcorrectivemea-

surestoeliminateorstopworkwhenrequired.

InspectionsAcompetentpersonmakesinspectionsanddocumentsthem.Thefollowingguidespecifiesthefrequencyandconditionsrequiringinspections:■ Dailyandbeforethestartofeachshift;

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■ Asdictatedbytheworkbeingdoneinthetrench;■ Aftereveryrainstorm;■ Afterothereventsthatcanincreasehazards,suchasasnowstorm,windstorm,

thaw,earthquake,etc.;■ Whenfissures,tensioncracks,sloughing,undercutting,waterseepage,bulg-

ingatthebottomorothersimilarconditionsoccur;■ Whenthereisachangeinthesize,locationorplacementofthespoilpile;■ Whenthereisanyindicationofchangeormovementinadjacentstructures.

On-the-jobevaluationThecompetentpersonmustinspectexcavationsandadjacentareasforpossiblecave-insonadailybasis,forfailuresofprotectivesystemsandequipment,haz-ardousatmospheresorotherhazardousconditions.Ifyouencounterthesecondi-tions,removeexposedemployeesfromthehazardousareauntilyoutakethenecessarysafetyprecautions.Inspectionsalsoarerequiredafternaturalevents,suchasheavyrainsorman-madeevents,suchasblastingthatmayincreasethehazardpotential.

Forlargerandmorecomplexoperations,itisimportanttohaveafull-timesafetyofficialtomakerecommendationstoimprovethesafetyplanimplementation.Inasmalleroperation,thesafetyofficialmayworkonsafetypart-timeandusuallywillbeasupervisor.

Supervisorsarethecontractor’srepresentativesonthejob.Theyconductinspec-tions,investigateaccidents,anticipatehazardsandensurethatemployeesreceiveon-the-jobsafetyandhealthtraining.Partoftheirjobistoreviewandstrengthenoverallsafetyandhealthprecautionstoguardagainstpotentialhazards,obtainthenecessaryworkercooperationinsafetymattersandmakefrequentreportstothecontractor.

Itisimportantthatmanagersandsupervisorssettheexampleforsafetyatthejobsite.Itisessentialthatallmanagersweartheprescribedpersonalprotectiveequipment(PPE),suchassafetyshoes,safetyglasses,hardhatsandotherneces-sarygearwhenvisitingthejobsite.Employeesalsomusttakeanactiveroleinjobsafety.Itistheresponsibilityofthecontractorandsupervisortomakecertainthatworkershavebeenproperlytrainedintheuseandfitoftheprescribedprotec-tivegearandequipment,thattheywearandusetheequipmentcorrectlyandthattheyusesafeworkpractices.

Theprimaryhazardtowhichemployeesmaybeexposedduringexcavationworkisacave-in,whichoccurswhenthesoilformingthesideoftheexcavationcannolongerresisttheforcesbeingappliedtoit,whenthesoil’sfrictionalandcohesivecapacitiestoresistforcesarereduced.Changingenvironmentalconditions,suchasfreezingandthawing,ortheadditionorremovalofwaterfromthesoil’sporescanreducethesoil’sabilitytoresistforces.Cave-insalsocanbecausedbydy-namicloadsfromvibrationscausedbynearbytrafficorconstructionoperations,suchaspiledriving,theadditionofsuperimposedloadsfromspoilpiles,ortheplacementofheavyequipmentormaterialsneartheedgeofanexcavation.

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Totheuntrainedandinexperiencedeye,adeeptrenchwallofseeminglyfirmclaycanbedeceptive,buttrenchcollapsecanoccurwithoutwarning,regardlessofthedepth.Mosttrenchingfatalitiesoccurintrenches5to15feetdeep.Becausethesedepthsinvitetakingchances,tragediescananddooccureveninsmallexcavationsortrenches.Atrenchjust4feetdeepcanbecomeashallowgrave.Manyfatalaccidentshaveoccurredinshallowtrenchesbecausethevictimswereworkinginabent-overorlyingpositionwhenthetrenchsidescollapsed.Eventhosewhomanagetosurviveoftensuffersevereandlifelongdisablinginjuriesbecauseofthecrushingweight.

Onecubicyardofearthcanweigh1.5tonsormore,andonecubicfootcanweighmorethan100pounds.Perhapsonlythosefortunateenoughtosurviveacave-incanappreciatethetremendouscrushingandsuffocatingforceofaloadofdis-lodgedearth.

Tragically,hundredsofworkersarekilledandthousandsareinjuredwhiledoingexcavationworkeveryyear.Whenapersonistrappedandcaughtbyacave-in,thecrushingpressurefromthematerialgraduallyrestrictsbreathing.Eachtimethevictimexhalesabreath,theweightoftheloadrestrictsinhalationofthenextbreath.Aslowsuffocationdeathusuallyfollows,unlessrescueisimmediate.

Mostrescueeffortresultsareunsuccessful.Therearetoomanythingsworkingagainstasuccessfulrescue—time,weightofthesoilandrestrictedaccesstothesite.Manytimes,coworkersandrescuepersonnelalsoareexposedtoadditionalcave-insandhazards.

Trenchingandexcavationsafetyguidelines■ Establishthelocationsofundergroundandoverheadutilitiesandservicesbe-

forebeginningexcavation.Contactutilitycompaniesandmunicipally-ownedutilitiesandadvisethempriortothestartofactualexcavation.

■ Makeaninspectionaftereveryrainfallorotherhazard-producingoccurrence,ifyouarethecompetentperson.

■ Donotallowwatertoaccumulateinexcavations.■ Useheaviersheetpiling,shoringorbracingwithsuperimposedloads,such

ascranesworkingclosetoexcavationedges.Usingmobileequipmentnearexcavationsalsorequiresextensivebarricadesorstoplogs.

■ Makesureemployeesworkingintrenches4feetdeepormorehaveanad-equateandsafemeansofexit,suchasladders,stepsorrampsavailableatnomorethan�5feetoflateraltravel.Inexcavationsmorethan�0feetdeep,equipladderswithladderplatformsat�0footintervals.

■ Makesureacompetentpersoncapableofidentifyingexistingandpredictablehazards,andwiththeauthoritytotakepromptcorrectiveactiontoeliminatethemisonthesite.ThepersonshouldbeabletoidentifysoilclassificationsandtheprotectivesystemstobeusedinaccordancewiththeOSHAtrenchingstandard.

■ Ensurethattrenchesmorethan5feetdeephaveshoringorarelaidbacktoastableslope.Inunstablesoil,trencheslessthan5feetdeepmustbeprotected.

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■ Design,constructandmaintainportabletrenchboxesorslidingtrenchshieldsusedinplaceofshoringandslopingtoprovideprotectionatleastequaltotherequiredsheetingandshoring.Ensurethataregisteredprofessionalengineerdesignstheshields.

■ Installshieldstorestrictlateralorotherhazardousmovement.■ Makesuretrenchboxesandshieldsextendtothebottomofthetrenchandno

lessthan6inchesabovetheverticalpartofthetrenchface,exceptincertaincases(seeOSHA19�6.65�).

■ Donotallowemployeesinshieldsduringtheirinstallation,removalorrelocation.

■ Provideameansofattachingtrenchboxeswhentheyarestackedtopreventthemfromseparating.

■ Donotworkoutsideoftrenchshieldsorshoringprotectioninunprotectedtrenches.

■ Donotridebucketstoenterorleaveatrench.■ Avoidjumpingintooracrosstrenches.■ Placetrenchjacksorcrossbracesintruehorizontalposition,spacedvertically

andsecuredtopreventsliding,fallingorkickouts.■ Useropestopulloutjacksorbracesafteremployeeshavevacatedthetrench;■ Performbackfillingandtrenchsupportremovaltogetherfromthebottomof

thetrench.Releasejacksandsupportsslowly.■ Makesurepiling,sheeting,shoring,shieldsandsupportsystemsaredesigned

andinstalledbyqualifiedpersonnelandthattheshoringsystemiscapableofwithstandingallloadsimposeduponit.

■ Ensurethatmaterialandequipmentusedforsheeting,sheetpiling,bracing,shoringandunderpinningareingoodserviceablecondition.Usetimbersthataresoundandfreeofdefects.

■ Storespoilatleast�feetawayfromwhereemployeesenterexcavations,oruseeffectiveretainingdevices.

■ Installadditionalunderpinningshoringorbracingwhenrequiredincaseswhereadjoiningutilitylines,foundations,walksandfootingsareendangered;

■ Extendverticalsupportsinthebracingsystemtoanelevationnolessthanonefootabovethetopofthetrenchface.

■ Erectstandardguardrailingorsolidsheetingnolessthan4�inchesabovegroundlevelaroundalltunnelshaftsandborepits.

■ Protectemployeesinbell-bottompierholesbyremovabletypesteelcasingsandindividually-mannedlifelinesandharnesses.Followconfined-spaceentryprocedures.

■ Protecteachemployeefromfallingbyusingguardrailsystems,fences,barri-cadesorcoversattheedgeofawell,pit,shaftandsimilarexcavation6feetormoreindepth.

■ Installstandardguardrailsystemsalongramps,runwaysorbridgesoverexca-vationsthataremorethan6feetdeep.

■ Backfilltrenchesastheworkprogresses.

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Chapter2Cave-insandprotectivesupportsystems

Workinginanexcavationexposesemployeestomanyhazardsofwhichacave-inisthechiefhazard.Youmustprotectemployeesexposedtopotentialcave-insinallexcavationsbyoneofthefollowing:■ Slopingorbenchingthesidesoftheexcavation;■ Supportingthesidesoftheexcavation;■ Placingashieldbetweenthesideoftheexcavationandtheworkarea.

Designingaprotectivesystemcanbecomplexbecauseofthenumberoffactorsinvolved—soilclassification,depthofcut,watercontentofsoil,changesduetoweatherandclimate,orotheroperationsinthevicinity.TheOSHAstandard,how-ever,providesseveralmethodsandapproachesfordesigningprotectivesystemsthatcanprovidetherequiredlevelofprotectionagainstcave-ins.

Onemethodofensuringthesafetyandhealthofworkersinanexcavationistoslopethesidestoananglenotsteeperthan1.5horizontaltoonevertical—34degreesmeasuredfromthehorizontal.Excavatetheseslopestoformcon-figurationsinaccordancewiththoseforTypeCsoilfoundinAppendixBofthestandard.Aslopeofthisgradationorlessisconsideredsafeforanytypeofsoil.Allsimpleslopeexcavationsthatare�0feetorlessindepthshallhaveamaximumallowableslopeof1.5-to-1.

Aseconddesignmethod,whichcanbeappliedforbothslopingandshoring,involvesusingtabulateddata,suchastablesandcharts,approvedbyaregisteredprofessionalengineer.Thesedatamustbeinwritingandmustincludesufficientexplanatoryinformationtoenabletheusertomakeaselection,includingthecri-teriafordeterminingtheselectionandthelimitsontheuseofthedata.

Keepatleastonecopyoftheinformation,includingtheidentityoftheregisteredprofessionalengineerwhoapprovedthedata,attheworksiteduringconstructionoftheprotectivesystem.Whenthesystemiscomplete,storethedataawayfromthejobsite,butmakeacopyavailable,uponrequest.

Contractorsalsomayuseatrenchboxorshieldthatiseitherdesignedorap-provedbyaregisteredprofessionalengineerorisbasedontabulateddatapreparedorapprovedbyaregisteredprofessionalengineer.OSHAstandardspermittheuseofatrenchshield—alsoknownasawelder’shut—aslongastheprotectionprovidedisequaltoorgreaterthantheprotectionthatwouldbepro-videdbytheappropriateshoringsystem.Theshieldcanbeconstructedoftimber,aluminumorothersuitablematerial.

Employerscanchoosethemostpracticaldesignapproachforanyparticularcircumstance.Onceyouselectanapproach,however,thesystemmustmeettherequiredperformancecriteria.

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Thestandarddoesnotrequiretheinstallationanduseofaprotectivesystemwhenanexcavationismadeentirelyinstablerockorlessthan5feetdeepandacompetentpersonhasexaminedthegroundandfoundnoindicationofapoten-tialcave-in.

InstallationandremovalThefollowingproceduresarerequiredfortheprotectionofemployeeswheninstallingsupportsystems:■ Securelyconnectmembersofsupportsystems;■ Safelyinstallsupportsystems;■ Neveroverloadmembersofsupportsystems;■ Installotherstructuralmemberstocarryloadsimposedonthesupportsystem

whentemporaryremovalofindividualmembersisnecessary.

Inaddition,thestandardpermitsexcavationof�feetorlessbelowthebottomofthemembersofatrench’ssupportorshieldsystemif:■ Thesystemisdesignedtoresisttheforcescalculatedforthefulldepthofthe

trench;■ Therearenoindications,whilethetrenchisopen,ofapossiblecave-inbelow

thebottomofthesupportsystem.

Also,theinstallationofsupportsystemsmustbecloselycoordinatedwiththeexcavationoftrenches.

Assoonasworkiscompleted,backfilltheexcavationastheprotectivesystemisdismantled.Aftertheexcavationhasbeencleared,haveworkersslowlyremovetheprotectivesystemfromthebottomup,takingcaretoreleasemembersslowly.

ShoringtypesShoringistheprovisionofasupportsystemfortrenchfacesusedtopreventmovementofsoil,undergroundutilities,roadwaysandfoundations.Useshoringorshieldingwhenthelocationordepthofthecutmakesslopingbacktothemaxi-mumallowableslopeimpractical.Shoringsystemsconsistofuprights,wales,strutsandsheeting.Therearetwobasictypesofshoring:timberandaluminumhydraulic.

Today’strendistowardusinghydraulicshoring,aprefabricatedstrutand/orwalesystemmanufacturedofaluminumorsteel.Hydraulicshoringprovidesacriticalsafetyadvantageovertimbershoringbecauseworkersdonothavetoenterthetrenchtoinstallorremovehydraulicshoring.Otheradvantagesofmosthydraulicsystemsarethatthey:■ Arelightenoughtobeinstalledbyoneworker;■ Aregauge-regulatedtoensureevendistributionofpressurealongthetrench

line;■ Canhavetheirtrenchfacespreloadedtousethesoil’snaturalcohesionto

preventmovement;■ Canbeadaptedeasilytovarioustrenchdepthsandwidths.

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Installallshoringfromthetopdownandremovefromthebottomup.Checkhydraulicshoringatleastoncepershiftforleakinghosesand/orcylinders,brokenconnections,crackednipples,bentbasesandanyotherdamagedordefectiveparts.

Pneumaticshoringworksinamannersimilartohydraulicshoring.Theprimarydifferenceisthatpneumaticshoringusesairpressureinplaceofhydraulicpres-sure.Adisadvantageofusingpneumaticshoringisthatanaircompressormustbeonsite.

Screwjacksystemsdifferfromhydraulicandpneumaticsystemsinthatyoumustadjustmanuallythestrutsofascrewjacksystem.Thiscreatesahazardbecausetheworkerisrequiredtobeinthetrenchtoadjustthestrut.Inaddition,uniformpreloadingcannotbeachievedwithscrewjacks,andtheirweightcreateshan-dlingdifficulties.

Single-cylinderhydraulicshoresaregenerallyusedinawatersystemasanassisttotimbershoringsystemsandinshallowtrencheswherefacestabilityisrequired.

Theunderpinningprocessinvolvesstabilizingadjacentstructures,foundationsandotherintrusionsthatmayhaveanimpactontheexcavation.Asthetermindicates,underpinningisaprocedureinwhichthefoundationisphysicallyrein-forced.Conductunderpinningonlyunderthedirectionandwiththeapprovalofaregisteredprofessionalengineer.

ShieldingtypesTrenchboxesaredifferentfromshoringbecause,insteadofshoringuporoth-erwisesupportingthetrenchface,theyareintendedprimarilytoprotectwork-ersfromcave-insandsimilarincidents.Maketheexcavatedareabetweentheoutsideofthetrenchboxandthefaceofthetrenchassmallaspossible.Thespacebetweenthetrenchboxesandtheexcavationsideareback-filledtopreventlateralmovementofthebox.Donotsubjectshieldstoloadsexceedingthosethatthesystemwasdesignedtowithstand.

CombineduseTrenchboxesaregenerallyusedinopenareas,buttheyalsomaybeusedincombinationwithslopingandbenching.Makesuretheboxextendsatleast18inchesabovethesurroundingareaifthereisslopingtowardexcavation.Youcanaccomplishthisbyprovidingabenchedareaadjacenttothebox.

Earthexcavationtoadepthof�feetbelowtheshieldispermitted,butonlyif:■ Theshieldisdesignedtoresisttheforcescalculatedforthefulldepthofthe

trench;■ Therearenoindicationswhilethetrenchisopenofpossiblelossofsoilfrom

behindorbelowthebottomofthesupportsystem.

Conditionsofthistyperequireobservationontheeffectsofbulging,heavingandboiling,aswellassurcharging,vibration,adjacentstructures,etc.,onexcavatingbelowthebottomofashield.Carefulvisualinspectionoftheconditionsprevi-ouslymentionedistheprimaryandmostprudentapproachtohazardidentifica-tionandcontrol.

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Chapter3Slopingandbenching

SlopingMaximumallowableslopesforexcavationslessthan�0feetbasedonsoiltypeandangletothehorizontalare:

Soil type Height/Depth ratio Slope angleStablerock Vertical 90degreesTypeA .75-to-1 53degreesTypeB 1-to-1 45degreesTypeC 1.5-to-1 34degreesTypeA(short-term) .5-to-1 63degrees

BenchingTherearetwobasictypesofbenching:simpleandmultiple.Thetypeofsoildeterminesthehorizontal-to-verticalratioofthebenchedside.Asageneralrule,thetrench’sbottomverticalheightmustnotexceedfourfeetforthefirstbench.Subsequentbenchesmaybeuptoamaximumof5feetverticallyinTypeAsoiland4feetinTypeBsoilforatotaltrenchdepthof�0feet.Allsubsequentbench-esmustbebelowthemaximumallowableslopeforthatsoiltype.ForTypeBsoil,thetrenchexcavationispermittedincohesivesoilonly.

Placetemporaryspoilnocloserthan�feetfromthesurfaceedgeoftheexcava-tion,measuredfromthenearestbaseofthespoiltothecut,notfromthecrownofthespoildeposit.Thisdistancerequirementensuresthatlooserockorsoilfromthetemporaryspoilwillnotfallonemployeesinthetrench.

Placespoilsothatitchannelsrainwaterandotherrun-offwaterawayfromtheexcavation,sothatitcannotaccidentallyrun,slideorfallbackintotheexcavation.

Placepermanentspoilatsomedistancefromtheexcavation.Permanentspoilisoftencreatedwhereunderpassesarebuiltorutilitiesareburied.Theimproperplacementofpermanentspoilcancauseanexcavationtobeoutofcompliancewiththehorizontal-to-verticalratiorequirementforaparticularexcavation.Thiscanusuallybedeterminedthroughvisualobservation.Permanentspoilcanchangeundisturbedsoiltodisturbedsoilanddramaticallyaltersloperequire-ments.

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Chapter4Othersafetyconsiderations

Piledriving■ Useablockingdevicewhenworkingunderleadsorhammerswhereabrake

orcablefailurecanresultininjuries.■ Makesureemployeesarenotontheleadswhenhoistingpilingintoplace.■ Makesurethatnopartofthebodyisexposedtopinchpointsbetweenpiling,

leadsandhammerswhenmakingfinaladjustmentsbeforedriving.■ Stackpilinginanorderlymannertopreventshifting.■ Inspectair-andsteam-lineconnectionsdaily.Attachachainorropeatthe

couplingpointstopreventwhipping.■ Makesurethatthehammerisatthelowestpossiblelevelwhenleadsand

hammersconnectedtothecranearemoved.■ Makesurethepersonsecuringpilingintheleadsisusingasafetyharness;■ Designateoneworkertosignaltheoperator.■ Inspectslingsandbridlesandreplacedamagedcablesdaily.■ Usetaglinestoguidethepilestotheleads.

CofferdamsThefollowingguidelinesarerecommendedforcofferdams:■ Provideameansforcontrolledfloodingoftheworkareaifovertoppingofcof-

ferdamsbyhighwatersispossible;■ Developandpostinstructionsforwarningsignalsforemployeeevacuationin

caseofanemergency;■ Provideandequipstandardguardrailsalongcofferdamwalkways,bridgesor

rampswithnofewerthantwomeansofrapidexit;■ Markcofferdamslocatedclosetonavigableshippingchannelstoprotectthem

fromvesselsintransit.

EntranceandexitTheemployermustprovidesafeaccessandegresstoallexcavations.AccordingtoOSHAregulations,whenemployeesarerequiredtobeintrenchexcavationsthatare4feetdeepormore,adequatemeansofexitsuchasladders,steps,rampsorothersafemeansmustbeprovidedandbewithin�5feetoflateraltravel.Ifstructuralrampsareusedasameansofaccessorexitforemployees,acompetentpersonmustdesignthem.Acompetentpersonqualifiedinstructuraldesignmustdesignrampsusedbyvehicles.Also,structuralmembersusedforrampsorrunwaysmustbeuniforminthicknessandjoinedinamannertopre-venttrippingordisplacement.Secureladdersandextendthemaminimumof36inchesabovethelanding.Usemetalladderswithcaution,particularlywhenelectricutilitiesarepresent.

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Whiletrenchingandexcavationworkpresentsseriousriskstoallworkersin-volved,thegreatestrisk,andoneofprimaryconcern,isthatofacave-in.Whencave-inaccidentsoccur,theyaremuchmorelikelytoresultinworkerfatalitiesthanotherexcavation-relatedaccidents.Strictcompliancewithallsectionsofthestandardwillpreventorgreatlyreducetheriskofcave-insaswellasotherexca-vation-relatedaccidents.

StandingwaterandwateraccumulationEmployeesareprohibitedfromworkinginexcavationswherewaterhasaccumu-latedorisaccumulatingunlessadequateprotectionisprovided.Ifwaterremovalequipmentisusedtocontrolorpreventwaterfromaccumulating,acompetentpersonmustmonitortheequipmentandoperationstoensureproperuse.

OSHAstandardsalsorequirethatemployersusediversionditches,dikesorothersuitablemeanstopreventsurfacewaterfromenteringanexcavationandtopro-videadequatedrainageoftheareaadjacenttotheexcavation.Also,acompetentpersonmustinspectexcavationssubjecttorunoffsfromheavyrains.

Providemethodsforcontrollingstandingwaterandwateraccumulationthatcon-sistofthefollowingifemployeesarepermittedtoworkintheexcavation:■ Useofspecialsupportorshieldsystemsapprovedbyaregistered

professionalengineer;■ Waterremovalequipment,suchaswellpointing,usedandmonitoredbya

competentperson;■ Safetyharnessesandlifelinesusedinconformancewith�9CFRPart19�6.104;■ Surfacewaterdivertedawayfromthetrench;■ Employeesremovedfromthetrenchduringrainstorms;■ Trenchescarefullyinspectedbyacompetentpersonaftereachrainandbefore

employeesarepermittedtore-enterthetrench.

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Chapter5Soilmechanics

Anumberofstressesanddeformationscanoccurinanopencutortrench.Forexample,increasesordecreasesinmoisturecontentcanadverselyaffectthestabilityofatrenchorexcavation.Tensioncracksusuallyformatahorizontaldistanceof0.5to0.75timesthedepthofthetrench,measuredfromthetopoftheverticalfaceofthetrench.Slidingorsloughingmayoccurasaresultoftensioncracks.Inadditiontosliding,tensioncrackscancausetoppling.Topplingoccurswhenthetrench’sverticalfaceshearsalongthetensioncracklineandtopplesintotheexcavation.

Anunsupportedexcavationcancreateanunbalancedstressinthesoil,which,inturn,causessubsidenceatthesurfaceandbulgingoftheverticalfaceofthetrench.Ifuncorrected,thisconditioncancausefacefailureandentrapmentofworkersinthetrench.

Thedownwardpressurecreatedbytheweightofadjoiningsoilcausesbottomheavingorsqueezing,causingabulgeinthebottomofthecut.Heavingandsqueezingcanoccurevenwhenshoringorshieldingisproperlyinstalled.

Boilingisevidencedbyanupwardwaterflowintothebottomofthecut.Ahighwatertableisoneofthecausesofboiling.Boilingproducesaquickconditioninthebottomofthecutandcanoccurevenwhenshoringortrenchboxesareused.

DeterminationofsoiltypeOSHAcategorizessoilandrockdepositsintofourtypes:■ Stablerockisnaturalsolidmineralmatterthatcanbeexcavatedwithvertical

sidesandremainintactwhileexposed.Itisusuallyidentifiedbyarockname,suchasgraniteorsandstone.Determiningthistypemaybedifficultunlessitisknownwhethercracksexistandwhetherornotthecracksrunintoorawayfromtheexcavation;

■ TypeAsoilsarecohesivesoilswithanunconfinedcompressivestrengthof1.5tonspersquarefoot(tsf)orgreater.ExamplesofTypeAcohesivesoilsareoften:clay,siltyclay,sandyclay,clayloamandinsomecases,siltyclayloamandsandyclayloam.NosoilisTypeAifitisfissured,issubjecttovibrationofanytype,hasprevi-ouslybeendisturbed,ispartofasloped,layeredsystemwherethelayersdipintotheexcavationonaslopeoffourhorizontaltooneverticalorgreater,orhasseepingwater;

■ TypeBsoilsarecohesivesoilswithanunconfinedcompressivestrengthgreaterthan0.5tsfbutlessthan1.5tsf.ExamplesofotherTypeBsoilsare:

■ Angulargravel; ■ Silt; ■ Siltloam; ■ PreviouslydisturbedsoilsunlessotherwiseclassifiedasTypeC; ■ Soilsthatmeettheunconfinedcompressivestrengthorcementation

requirementsofTypeAsoilsbutarefissuredorsubjecttovibration; ■ Dryunstablerockandlayeredsystemsslopingintothetrenchataslope

lessthana4-to-1ratio(onlyifthematerialwouldbeclassifiedasaTypeB soil).

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■ TypeCsoilsarecohesivesoilswithanunconfinedcompressivestrengthof0.5tsforless.OtherTypeCsoilsincludegranularsoils,suchasgravel,sandandloamysand,submergedsoil,soilfromwhichwaterisfreelyseeping,andsub-mergedrockthatisnotstable.Also,includedinthisclassificationismaterialinasloped,layeredsystemwherethelayersdipintotheexcavationorhaveaslopeoffourhorizontaltooneverticalorgreater.

Wheresoilsareconfiguredinlayers,suchaswherealayeredgeologicstructureexists,thesoilmustbeclassifiedonthebasisofthesoilclassificationoftheweak-estsoillayer.Eachlayermaybeclassifiedindividuallyifamorestablelayerliesbelowalessstablelayer,suchasifaTypeCsoilrestsontopofstablerock.

TestequipmentandmethodsforevaluatingsoiltypeManykindsofequipmentandmethodsareusedtodeterminethetypeofsoilprevailinginanarea.■ Pocketpenetrometer—Adirectreading,spring-operatedinstrumentusedto

determinetheunconfinedcompressivestrengthofsaturatedcohesivesoils.Oncepushedintothesoil,anindicatorsleevedisplaysthereading.Theinstru-mentiscalibratedintsforkilogramspersquarecentimeter(kPa).However,penetrometershaveerrorratesintherangeof±�0percentto40percent.

■ Shearvane(Torvane)—Adeviceusedtodeterminetheunconfinedcompres-sivestrengthofthesoil.Withashearvane,pressthebladesofthevaneintoalevelsectionofundisturbedsoilandturnthetorsionalknobslowlyuntilsoilfailureoccurs.MultiplythedirectinstrumentreadingbytwotoprovidetheresultsintsforkPa.

■ Thumbpenetrationtest—Aprocedurethatinvolvespressingthethumbfirmlyintothesoilinquestion.Ifthethumbmakesanindentationinthesoilonlywithgreatdifficulty,thesoilisprobablyTypeA.Ifthethumbpenetratesnofurtherthanthelengthofthethumbnail,itisprobablyTypeBsoil.Ifthethumbpenetratesthefulllengthofthethumb,itisTypeCsoil.Thethumbtestissubjectiveandtherefore,istheleastaccurateofthethreemethods.

■ Drystrengthtest—Atestthatdeterminesifdrysoilcrumblesintoindividualgrainsfreelyorwithmoderatepressure.Drysoilthatfallsintoclumpsthatsubsequentlybreakintosmallerclumps—andthesmallerclumpscanbebro-kenonlywithdifficulty—isprobablyclayincombinationwithgravel,sandorsilt.Ifthesoilbreaksintoclumpsthatdonotbreakintosmallerclumps—andthesoilcanbebrokenonlywithdifficulty—thesoilisconsideredunfissuredunlessthereisvisualindicationoffissuring.

■ Plasticityorwetthreadtest—Atestconductedbymoldingamoistsampleofthesoilintoaballandattemptingtorollitintoathinthreadapproximatelyone-eighthinchindiameterby�inchesinlength.Holdthesoilsamplebyoneend.Ifthesampledoesnotbreakortear,thesoilisconsideredcohesive.

■ Visualtest—Aqualitativeevaluationofconditionsaroundthesite.Observetheentireexcavationsite,includingthesoiladjacenttothesiteandthesoilbeingexcavated.Ifthesoilremainsinclumps,itiscohesive;ifitappearstobecoarse-grainedsandorgravel,itisconsideredgranular.

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Thecompetentpersonalsochecksforanysignsofvibration.Duringavisualtest,thecompetentpersonchecksforcrack-lineopeningsalongthefailurezonethatindicatestensioncracks,looksforexistingutilitiesthatindicatethatthesoilhaspre-viouslybeendisturbedandobservestheopensideoftheexcavationforindicationsoflayeredgeologicstructuring.

Itistheresponsibilityofthecompetentpersontolookforsignsofbulging,boilingorsloughing,aswellasforsignsofsurfacewaterseepingfromthesidesoftheexcavationorfromthewatertable.Ifthereisstandingwaterinthecut,thecompe-tentpersoncheckstheseconditions.Inaddition,thecompetentpersoncheckstheareaadjacenttotheexcavationforsignsoffoundationsorotherintrusionsintothefailurezone,andforsurchargingandthespoildistancefromtheedgeoftheexca-vation.

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Chapter6Materialsandequipment

HeavyequipmentGuidelinesforoperatingheavyequipmentinclude:■ Inspectequipmentcarefullyatthebeginningofeachshift;■ Learnthesafestmethodofmountingandleavingmachines;■ Knowthelimitationsofoperatingmachinesonslopesandroughterrain;■ Reportmalfunctionstothesupervisorormastermechanic;■ Ensurethatallequipmentissecuredtopreventitfrombeingstartedormoved

byanunauthorizedperson;■ Maketurnsonsteepgradesinanuphilldirection;■ Blocktheaprononscrapersbeforechangingblades;■ Followestablishedtrafficpatternsonhaulroads;■ Makesurethatthebrakeisoperativebeforemovingequipment;■ Climbdownfromequipment.Donotjump;■ Keepyourequipmentasafedistancefromtheedgeofembankments;■ Shutofftheengineonallequipmentbeforemakingadjustmentsorrepairs;■ Donotengageinhorseplay;■ Maintainallrequiredlights,reflectorsandaccessoriesonequipment;■ Donottravelwiththebucketofanend-loaderraisedabovethetopofthe

radiatorofthemachine,sinceitwillobstructtheoperator’sview;■ Lookinthedirectionthattheequipmentistraveling;■ Beforeloadingatruck,findoutwhatisontheothersideofit;■ Lowerloaderbucketstothegroundwhennotinuse;■ Keepreversealarmsoperableandfreeofanythingthatwillmufflethesound;■ Wearseatbeltsonequipmentwitharolloverprotectionsystem;■ Makesureequipmentusedinsite-clearingoperationshassubstantialover-

headguards,shields,canopiesandgrills;■ Donotusethebladetobrakebulldozersondownhillrunsexceptin

emergencies;■ Donotallowpassengersonamachinewhileitisinuse;■ Becertaineveryoneisoutofthewaybeforepushingovertrees,rollinglogsor

dozingrocks;■ Remainclearofthetowropewhentowingamachine;■ Readtheoperator’smanual.Itcontainsimportantinformationontheequip-

mentbeingoperated;■ Ensurethatotherworkersareoutofthewaybeforestartingthemachine;■ Inspecttheequipmentdaily.Becertainallsafeguardsareinplaceonthe

equipmentandreportanydefectsimmediately;■ Placeawarningtagonthesteeringwheelorignitionswitchofallunsafe

equipmentbeingrepaired;■ Guardorinsulateallhotsurfacesoftheequipment,includingexhaustpipesor

otherlines,topreventinjuryorfire;■ Makesurethatexhaustordischargesfromtheequipmentaredirectedsothat

theydonotendangerpeopleorobstructtheoperator’sview.

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WarningsystemsformobileequipmentThefollowingguidelineswillhelppreventvehiclesfromaccidentallyfallingintothetrench:■ Installbarricadeswherenecessary;■ Usehandormechanicalsignalsasrequired;■ Installstoplogsifthereisadangerofvehiclesfallingintothetrench;■ Gradesoilawayfromtheexcavation;thiswillassistinvehiclecontroland

channelingofrun-offwater.

ManualmaterialhandlingThefollowingguidelinesarerecommendedformanualmaterialhandlingandlifting:■ Neversmokeduringrefueling.Beforestartingtorefuel,turnmotorsoff;■ Knowthelocationoffirefightingequipment;■ Prohibitunauthorizedridingonequipment;■ Knowyourlimits.Gethelpwithheavyorawkwardloads,orusemechanical

equipment;■ Tryapreliminaryliftfirsttobesurethatyoucanraisetheloadeasily.Ifitistoo

heavy,gethelp;■ Whenlifting,makesureyouhavesolidfootingandgetafirmgrip;■ Walk;neverrunwithaload;■ Nevertwistyourbodywhenturningwithaload.Instead,turnyourfeet;■ Arrangetocarrytheloadsoyourvisionisunobstructed.

Theemployerisresponsibleforthesafeconditionofmaterialsandequipmentusedforprotectivesystems.Defectiveanddamagedmaterialsandequipmentcanresultinfailureofaprotectivesystemandcauseexcavationhazards.

Toavoidpossibleprotective-systemfailure,theemployermustensurethat:■ Materialsandequipmentarefreeofdamageordefects;■ Manufacturedmaterialsandequipmentareusedandmaintainedinamanner

consistentwiththemanufacturer’srecommendationsandinawaythatpre-ventsemployees’exposuretohazards;

■ Acompetentpersonexaminesdamagedmaterialsandequipmenttodeter-minesuitabilityforcontinueduse.Ifmaterialsandequipmentarenotsafeforuse,theymustberemovedfromservice.Thesematerialscannotbereturnedtoservicewithouttheevaluationandapprovalofaregisteredprofessionalengineer.

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Chapter7Fallsandexposuretofallingloads

Inadditiontocave-inhazardsandrelatedsecondaryhazards,employersmustprotectworkersfromotherhazardsduringexcavation-relatedwork.Thesehaz-ardsincludeexposuretofalls,fallingloadsandmobileequipment.Toprotectemployeesfromthesehazards,employersarerequiredto:■ Keepmaterialsorequipmentthatmightfallorrollintoanexcavationatleast

twofeetfromtheedgeofexcavationsorhaveretainingdevices,orboth;■ Providewarningsystems,suchasmobileequipment,barricades,handorme-

chanicalsignals,orstoplogstoalertoperatorsoftheedgeofanexcavation.Ifpossible,keepthegradeawayfromtheexcavation;

■ Providescalingtoremovelooserockorsoil,orinstallprotectivebarricadesandotherequivalentprotectiontoprotectemployeesagainstfallingrocks,soilormaterials;

■ Prohibitemployeesfromworkingonfacesofslopedorbenchedexcava-tionsatlevelsaboveotheremployeesunlessemployeesatlowerlevelsareadequatelyprotectedfromthehazardoffalling,rollingorslidingmaterialandequipment;

■ Prohibitemployeesfromareasbeneathloadsthatarehandledbyliftingordiggingequipment.Toavoidbeingstruckbyanyspillageorfallingmaterials,requireemployeestostandawayfromvehiclesbeingloadedorunloaded.Ifavehicle’scabprovidesadequateprotectionfromfallingloadsduringloadingandunloadingoperations,theoperatormayremaininit.

SurfacecrossingoftrenchesDiscouragecrossingtrenchsurfaces.Howeveriftrenchesmustbecrossed,suchcrossingsarepermittedonlyunderthefollowingconditions:■ Designandinstallvehiclecrossingsunderthesupervisionofaregisteredpro-

fessionalengineer;■ Providewalkwaysorbridgesforfoottraffic;■ Makesurethesestructureshave: ■ Asafetyfactoroffour; ■ Aminimumclearwidthof18inches; ■ Standardrails.

ExposuretofallingloadsEmployersmustprotectemployeesfromloadsorobjectsfallingfromliftingordiggingequipment.Proceduresdesignedtoensuretheirprotectioninclude:■ Employeesarenotpermittedtoworkunderraisedloads;■ Employeesarerequiredtostandawayfromequipmentthatisbeingloadedor

unloaded;■ Equipmentoperatorsortruckdriversmaystayintheirequipmentduringload-

ingandunloadingiftheequipmentisproperlyequippedwithacabshieldoradequatecanopy.

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Chapter8Heat-andcold-relatedillnessesandtreatments

HeatOverexposuretoheatcancauseheatcramps,heatexhaustionorheatstroke,whichareseriousillnessesthatneedtobetreatedimmediately.Getthepersonoutofthesunasquicklyaspossible.

Heatcramps—painfulmusclespasmsthatusuallyoccurinthelegsandabdo-men—aretheleastsevereandareoftenthefirstsignalthatthebodyishavingtroublewiththeheat.Ifapersonhasheatcramps,takehimorhertoacoolplace,loosenclothingandgivehimorhercoolwateroracommercialsportsdrink.Allowthepersontodrinkaboutoneglassofliquidevery15minutes.Keepthepersondrinkingfluidsandwatchforanyfurthersignsofheat-relatedillness.

Heatexhaustionismoreseriousthanheatcramps.Symptomsincludecool,moist,paleorflushedskin,headache,nausea,dizziness,weaknessandexhaus-tion.Aswithheatcramps,getthepersontoacoolplaceandloosenthevictim’sclothing.Giveplentyoffluidstoaheatexhaustionvictim,andapplycold,wetcompressestocooltheperson.

Heatstrokeisthemostsevereheatcondition,developingwhenthebodysystemsareoverwhelmedbyheatandbegintostopfunctioning.Thesignalsincludered,hot,dryskin;changesinconsciousness;rapid,weakpulse;andrapid,shallowbreathing.Worktocooltheperson,asintheothertwoheat-relatedillnesses,butalsocallformedicalhelp.

Refusingwater,vomitingandchangesinconsciousnessindicatetheperson’sconditionisworsening.Getmedicalattentionimmediately.Ifthepersonvomits,donotgiveanymorefluidsandputthevictimonhisorhersidetopreventthepersonchokingonvomit.Watchforbreathingproblemsandkeepthevictimlyingdown.Coolthebodyasmuchaspossible.Placecold,wetclothsoricepacksonthevictim’swrists,ankles,groinarea,armpitsandnecktocoolthelargebloodvessels.Donotapplyrubbingalcohol.

Tohelppreventheat-relatedillnesses:■ Becomeacclimatedtotheheatgraduallybeforeworkinginhottemperatures

foralongtime;■Alwaysdrinkplentyofcoolwater;■ Wearhatsandsunglassestohelpstaycool;■ Takefrequentbreaksinacoolplace,ifpossible;■ Wearlooseclothingthatallowstheskintobreathe,suchascotton;■ Protectyourskinfromthesun.Keepasmuchofitcoveredwithclothingas

possible.Wearinglong-sleevedshirtswillhelp;■ Usesunscreenorsunblockonunprotectedskin.Physiciansrecommendasun-

blockwithasun-protectionfactorof15orgreater.Re-applysunblockregularlyifperspiringheavily.Makesuretoapplysunblocktohands,face(especiallynose)andears;

■ Conductperiodicself-examinationtoaidinearlyrecognitionofnewordevel-opinglesions.

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ColdColdweatherprimarilyaffectsthebody’sextremitiesbecausetheextremitiesarethinnerthanthecoreandcooldownfaster.Handsandfeetarefarthestfromthebodycoreandhavelessbloodflowthanthecore.Coldexposurecanoccurinweatherthatisnotfreezing.Whenthewindblows,thewindchillfactortakesef-fect.Thewind,humidityandmoistureremovebodyheat.

Dressaccordingtotheweather.Wearseverallayersofloose,bulkyclothingtoprovidebetterinsulation.Youcanremovealayerifthebodybecomesoverheat-ed.Avoidwearingtightclothing,itreducesbloodcirculation.Inextremelycoldweather,protecttheears,face,handsandfeet.Ahatwillkeepyourentirebodywarmerbyreducingheatlossfromthehead.Wearacouplepairsofsocksandinsulated,waterproofboots.

Onextremelycolddays,limittheamountoftimeoutside.Moveintoawarmlocationperiodically.Carrycoldweathersurvivalgear,includingathermosofhotliquid,achangeofclothes,extrasocks,gloves,hats,ajacketandblankets.

Whenitiscold,donottouchorbrushupagainstmetalsurfaceswithbareskinbecausetheskinmaysticktoitandgetimmediatefrostbite.Greasesandoilsgetthickandhard,whichmakesequipmentdifficulttouse.Ifyoumustheatequip-menttomakeitwork,followtheproperproceduresandusetherighttools.Toolsalsogetbrittleinthecold,sousecaution.

Workingwiththefeetundercoldwaterorinwetfieldsforalongtimecausestrenchfootorimmersionfoot.Thefeetfeelcoldandnumb,andblistersoftenform.Asthefeetbegintowarm,theybecomeredandfeelhot.Tocarefortrenchfoot,graduallywarmandelevatethefeet.Putonasteriledressing,takingcarenottobreaktheblisters.Getmedicalattention,becausetrenchfootcancauseseveredisability.

Repeated,prolongedexposuretocoldweathercancausechilblains-—red,swol-lenareasthatfeelhot,tenderanditchy.Chilblainscanoccurontheears,fingersandtoesandarechronic,whichmeanstheycanre-occurwhenthereisanotherprolongedexposuretocoldweather.Ifchilblainsoccur,covertheaffectedareaandseeaphysician.

Hypothermiaisthegeneralcoolingoftheentirebody.Whenbodytemperaturedropsmuchbelownormal,problemscanarise.Symptomsofhypothermiain-cludeuncontrollableshivering,numbness,drowsinessanddifficultydoingsimpletasks.Ashypothermiaprogresses,theshiveringstops,breathingandpulserateslowdownandeyesightmaybegintofail.Thepersonmaybegintostaggerandbecomeuncoordinated.Ifthepersondoesnotreceivetreatment,heorshemaybecomeunconscious,andpossiblydie.

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Totreathypothermiavictims,immediatelygetthemintoawarmenvironmentandgraduallywarmthem.Neverimmersethepersoninwarmwater;thewaterwarmsthevictimtooquickly.Removeanywetclothing,drythepersonanddresshimorherindryclothing.Wraphimorherinblankets,anduseheatingpadsandotherheatsourcestowarmthem.Keepabarrier,suchasablanket,towelorclothingbetweenthepersonandtheheatsource.Ifthepersonisalert,givehimorherwarmliquids.Getmedicaltreatmentforthevictimimmediately.Handlethepersongentlyuntilmedicalhelparrives.

Frostbiteoccurswhenpartsofthebodyfreeze.Icecrystals,whichcandestroythetissueandkilltheaffectedpart,forminsidetheskin.Theareasmostoftenaffectedaretheears,nose,fingersandtoes.Frostbittenareasinwhite-skinnedpeopleturnreddishandcanbepainful.Frostbittenareasturnpaleondark-skinnedpeople.Thepainsubsidesandtheareacanbecomenumb.Theareathenbecomeswhiteorgrayish-yellowandverycoldtothetouch.

Totreatvictimsoffrostbite,graduallywarmthearea.Donotusealcoholorrubthefrostbittenskin.Uselukewarmwatertosoaktheaffectedpart.Looselyban-dagetheareawithadry,steriledressing,takingcarenottobreakanyblisters.Getmedicalattentionassoonaspossible.

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Chapter9Lockout/tagout

Workersarekilledorseriouslyinjuredwhenmachinerystartstooperateandbecomesenergizedwhenitissupposedtobeturnedoff.Thesetypesofincidentshappenmostoftenwhilemachineryisbeingrepairedormaintained.Electricityisthemostcommontypeofenergyusedtorunmachinery,buthydraulic,pneumat-ic,mechanical,gravity,heatorchemicalenergyareothertypesofenergyusedtorunequipment.

Thetwomostcommonwaystoprotectworkersfrominjuriescausedbytheop-erationofmachinerywhentheequipmentissupposedtobeshutoffare:■ Lockout—Theon/offswitchorvalveissetintheoffposition.Akeyorcom-

binationlockisplacedoverthedevicethatturnsonthemachinerysothatitstaysintheoffpositionuntilthemachineisservicedandreadytobestartedupagain;

■ Tagout—Atagisattachedtotheswitch,circuitbreakerorvalvewhenthemachineryisturnedofftokeeptheequipmentfrombeinguseduntilthetagisremoved.Lockoutissaferthantagout.Usethelockoutmethodwheneverpos-sible.

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Chapter10Hazardousatmospheresandconfinedspaces

Underthisprovision,acompetentpersonmusttestexcavationsgreaterthan4feetdeepaswellasoneswhereoxygendeficiencyorahazardousatmosphereexistsorcouldreasonablybeexpectedtoexist,beforeanemployeeenterstheexcavation.Ifhazardousconditionsexist,providecontrols,suchasproperre-spiratoryprotectionorventilation.Also,regularlytestcontrolsusedtoreduceatmosphericcontaminantstoacceptablelevels.

Whereadverseatmosphericconditionsmayexistordevelopinanexcavation,theemployeralsomustprovideandensurethatemergencyrescueequipment,suchasabreathingapparatus,asafetyharnessorline,basketstretcher,etc.,isreadilyavailable.Thisequipmentmustbeattendedwheninuse.

Whenanemployeeentersbell-bottompierholesandsimilardeepandconfinedfootingexcavations,theemployeemustwearaharnesswithalifeline.Thelifelinemustbesecurelyattachedtotheharnessandmustbeseparatefromanylineusedtohandlematerials.Also,whiletheemployeewearingthelifelineisintheexcavation,anobservermustbepresenttoensurethatthelifelineisworkingproperlyandtomaintaincommunicationwiththeemployee.

Donotpermitemployeestoworkinhazardousand/ortoxicatmospheres.Suchatmospheresincludethosewith:■ Lessthan19.5percentormorethan�3.5percentoxygen;■ Acombustiblegasconcentrationgreaterthan�0percentofthelowerflam-

mablelimit;■ Concentrationsofhazardoussubstancesthatexceedthosespecifiedinthe

ThresholdLimitValuesforAirborneContaminantsestablishedbytheAmeri-canConferenceofGovernmentalIndustrialHygienists(ACGIH).

Whentestingforatmosphericcontaminants:■ Conducttestsbeforeemployeesenterthetrenchandthenre-testregularlyto

ensurethatthetrenchremainssafe;■ Increasethefrequencyoftestingifequipmentisoperatinginthetrench;■ Increasetestingfrequencyifwelding,cuttingorburningisdoneinthetrench;■ Train,fit-testandenrollemployeesrequiredtowearrespiratoryprotectionina

respiratoryprotectionprogram;■ Sometrenchesqualifyasconfinedspaces.Whenthisoccurs,complywith

OSHA’sConfinedSpaceStandard.

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ConfinedspacesAconfinedspaceisanareawithasmallopeningthatislargeenoughforsome-onetoenterandwork.Thesizeandshapeofthespacecanmakeithardtomovearoundorworkinforalongtime.Examplesofconfinedspacesincludeman-holes,tunnels,sewersandsewersilos,sewagedigesters,utilityvaults,pumpingstations,storagetanksandpits,vatsandprocessvessels.

Theairinaconfinedspacecanbeanunsafe,hazardousatmosphereforanumberofreasons:■ Notenoughoxygen—airthathaslessthan19.5percentoxygenisdanger-

ous.Withoutenoughoxygen,workerswilldiebecausetheywillnotbeabletobreathe;

■ Toomuchoxygen—airthathasmorethan�3.5percentoxygenincreasesfirehazards;

■ Flammablegases(gasesthatwillignite)—Methaneisthemostcommonflam-mablegasinsewers.Methaneisformedwhenmaterialsdecompose;

■ Toxicgasesandvaporscankillwhenlevelsarehigh.Hydrogensulfidesmellslikerotteneggsandsinkstothebottomofthespace.Carbonmonoxideisadeadlygasthatyoucannotsmell.

Otherhazardsofconfinedworkspaceincludeloudnoises,andslipsandfallscausedbywetsurfaces.

Thefollowingactionsareneededtoprotectworkersfromthehazardsthatcanbepresentinconfinedspaces:

1.Trainworkersandsupervisorsaboutthehazardsofconfinedspacesandhowtoprotectworkers;

�.Filloutanentrypermitbeforeaworkerentersaconfinedspace.Thepermitshouldcontainthefollowinginformation: ■ Thelocationofthespace,whenitwillbeenteredandforwhatpurpose; ■ Thesupervisorincharge; ■ Thepersonoutsideofthespace(attendant)responsibleforletting

workersknowiftheymustevacuatethespaceorwhotocallforhelp inanemergency;

■ Testresultsfordangersintheair; ■ Hazardsinthespaceandhowtheywillbecontrolled; ■ Emergencyandrescueservicesthatcanbecalled.

3.Testtheairforhazardsbeforeentering.Holdthemonitor—thedeviceusedtomeasuretheair—fromoutsidetheconfinedspace.Firsttesttheareaforoxygen.Theairmusthavebetween19.5and�3.5percentoxygen.Makesurethemoni-torreachesthelowestpointinthespace.Gases,suchashydrogensulfide,areheavierthanairandsinktothebottom.Othergases,suchasmethane,arelighterthanairandrisetothetop.Takesamplesfromthebottom,middleandtoplevels.

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4.Ventilatetheareabeforeenteringifthemonitorshowsthereisnotenoughoxygenorifitcontainstoxicgases.Airthatissafetobreatheisforcedintotheconfinedspace.Monitortheairagaintomakesuretheventilationhasremovedthehazardsintheair.

5.Usetherightprotectiveequipment.Thetypeofprotectiveequipmentneededdependsonthehazardsthatarepresent.Equipmentcommonlyusedforconfinedspaceworkincludes:■ Anair-suppliedrespiratorwhenthereistoolittleoxygenortoxicgases;■ Afullbodyorchestharnessandalifelinetomakearescue;■ Hardhats,safetygoggles,faceshields,gloves,disposablesuitsandear

protection;■ Anon-sparkingflashlight.

6.Bereadytomakearescuewithouthavingtoenterthearea!Toooften,work-ersdieinconfinedspaceswhiletryingtorescueaco-worker.Trainemployeesonrescueprocedures.Bepreparedtomakeanon-entryrescueincaseofanemergency.Arescuecanbemadewithouthavingtoenterthespacebyusingtri-pods,winchesandothertypesofretrievalsystems.Theattendantmaynotenterthespacetomakearescueuntilanotherattendanthasarrivedonthescene.

Proceduresforsafeconfined-spaceentryThefollowingguidelinesarerecommendedforsafeconfined-spaceentry:■ Establishanduseaprocedureforsafeentryintoconfinedspaces;■ Checkforandremoverodents,insects,debrisandwaterfromthespace;■ Ensurethattheserecommendedprocedurescomplywiththestandards:■ Designateatleastonetrainedpersontoberesponsibleforadherencetoentry

proceduresandrequirewrittenapprovalbythatpersonbeforepermittingany-onetoentertheconfinedspace;

■ Postestablishedentryproceduresimmediatelyadjacenttoallconfined-spaceentryports.Postrequirementsforrespiratoryequipmentandtestingequip-mentoncrewtrucks;

■ Provideperiodicinstructionandtraininginproperentryprocedures;■ Requirestandbypersonnel,whereprovided,tobeincommunicationatall

timeswiththeemployeewithintheconfinedspace.Analarmortwo-wayradiosystemforthestandbyemployeewillbeeffective;

■ Makesureapprovedrescueequipmentisavailable.Sinceentryportsforcon-finedspacesvaryinsize,takecaretoobtainequipmentofthepropersize;

■ Establishprocedurestopreventignitionofcombustibleatmospheresorre-entryofgasesorliquidsbylockingoutswitchesandblankingofftransmissionpipes.Usenon-sparkingtools;

■ Preventthegenerationofcontaminantsbyneutralizingorflushingoutresidualmaterials;

■ Useonlyapprovedinstrumentsinproperworkingorderwhentestingforcontaminants;

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■ Continuallymonitoroxygenandcontaminantconcentrationsduringoccupancy;

■ Makesurethatifrespiratoryequipmentleadingtoanaircompressorpipedsystemisused,thissystemmeetsthespecificationsoftheCompressedGasAssociationtoensureasupplyofuncontaminatedair;

■ Ensurethatpersonnelwhowillusesupplied-airorself-containedrespiratoryapparatusaretrainedinitssafeandproperuse;

■ Considerusingtagstoshowthataconfinedspacemaybeenteredsafely.

EmergencyrescueproceduresandequipmentInallcaseswhenanemployeeisstationedoutsideacompartment,tankorspaceasatenderforemployeesworkinginside,makesurethetenderhasallneces-saryPPEimmediatelyavailableforemergencyuse.HavethetenderwearPPEifexposedforprolongedperiodstosubstancesthatarehazardoustothetender’shealth.

Emergencyrescueequipmentisrequiredwhenahazardousatmosphereexistsorcanreasonablybeexpectedtoexist.Requirementsare:■ Respiratorsmustbeofthetypesuitablefortheexposure.Employersmust

trainemployeesintheiruseandinstitutearespiratorprogram;■ Youmustprovidelifelines,whichareattendedatalltimes,whenemployees

enterbell-bottompierholes,deepconfinedspaces,atoxicorflammableatmo-sphereorothersimilarhazardareas;

■ Employeeswhoenterconfinedspacesmustbetrained.

HazardcommunicationstandardMakeemployeesawareofthehazardoussubstancestowhichtheyareexposed.Awrittenhazardcommunicationprogram,includinglabels,materialsafetydatasheetsandtraining,isrequired.

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Chapter11Personalprotectiveequipment(PPE)

PPEisrequiredtoreduceemployees’exposurestohazardswhenengineeringoradministrativecontrolsarenotfeasibleoreffectiveinreducingtheseexposurestoacceptablelevels.EmployersarerequiredtodetermineallexposurestohazardsintheirworkplacesanddetermineifPPEshouldbeusedtoprotecttheirworkers.

IfusingPPEtoreduceemployeeexposuretohazards,startandmaintainaPPEprogramincluding:methodstoidentifyandevaluateworkplacehazardsanddetermineifissuingPPEisanappropriatecontrolmeasure;plandevelopmenttoselect,maintainandevaluateitsuse;trainingofemployeesusingthePPE;andprogramvigilancetodetermineitseffectivenessinpreventingemployeeinjuryorillness.

ThefollowingguidelinesforPPEusearerecommended:■ Wearhardhatsforprotectionfromfallingorflyingobjects,physicalcontact

withrigidobjects,electricalshockandhairentanglement;■ Wearashirtatalltimesforprotectionfromburns,abrasions,insectbitesand

lacerations;■ Maintainworkshoesingoodconditionforsolidandsecurefooting;■ Wearawarningvestintrafficareas;■ Usepropereyeandfaceprotectionwhenoperatingsawsandothercuttingor

chippingtools;■ Weargloveswhenthereisdangerofburns,abrasions,cutsorlacerations.

Wearrubberorneoprenegloveswhenworkingwithchemicalsharmfultotheskin;

■ WearrespiratorsthatareapprovedbytheNationalInstituteforOccupationalSafety&Healthwhereandwhenjobhazardsmakethemnecessary.Useandmaintainthemaccordingtothemanufacturer’srecommendations;

■ Workinawell-ventilatedarea;■ Wearhearingprotectionwhenexposedtoexcessivenoiselevels.Thecon-

finedspaceofatrenchcanincreasenoisehazards;■ UseproperPPEwhenhandlingwasteorpotentiallyhazardousmaterials;■ Complywithapplicablesafetyruleswhenusingmaterial-handlingequipment;■ Wearrubberboots,glovesandapronswhenexposedorincontactwithraw

sewageofwastewatersystems.Providesanitarywashingfacilitiesforcleanup.

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Chapter12Lasers(Non-ionizingradiation)

Thefollowingguidelinesarerecommendedforlasersystemswithlessthanfivemilliwattsofpower—0.005watts:■ Assignonlyqualifiedandtrainedemployeestoinstall,adjustandoperatelaser

equipment.Ensurethatproofofthelaserequipmentoperator’squalificationisavailableandintheoperator’spossessionatalltimes;

■ Useonlymechanicalorelectronicmeansasadetectorforguidingtheinternalalignmentofthelaser;

■ Donotlookdirectlyintothelaserbeamordirectthelaserbeamatemployees;■ Positionthelaseratalevelotherthantheeyelevelofpersonsinthearea,

whenpossible;■ Postlaserwarningsigns:“Notice—LaserinUse;”■ Turnthelaserofforcapthelenswhenitisnotbeingusedorisunattended;■ Providelaserequipmentwithlabelsstatingitslightintensityandthemanufac-

turer’snameandaddress;■ Prohibittheoperationoflasersystemswhenitisrainingorsnowing,orwhen

thereisdustorfogintheair,wherepracticable.Alwayskeepemployeesoutofsourceandtargetareasduringsuchweatherconditions.

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Chapter13Trafficcontrolandfleetsafety

Apropertrafficcontrolprogramshould:■ Getthedriver’sattentionintimetofollowdirections;■ Warnthedriverofthesituationahead;■ Slowthevehicle;■ Guidethedriversafelyaroundtheworksite;■ Returnthedrivertothenormaltrafficflow.

Warningsignsofstandardcolor,shape,sizeandsymbolsarethemostcommonwaytomakedriversawareofworkzones.Flaggersalsocanletdriversknowaboutroadworkbeingperformedanddirecttraffic.

Toensuresafetrafficcontrol:■ Makesureworkersareaseasytoseeaspossible.Haveflaggerswearhard

hats,redororangereflectivewarningvestsandusesignpaddles;■ Ensurethatworkzonesarewell-litifworkisdoneinthedark,reducingthe

chanceofaworkerbeingstruckbypassingvehiclesorbyotherequipmentusedonthejob;

■ Use“FlaggerAhead”signsattheapproachtoyourlocation;■ Useconesorbarrelstochanneltraffic.Trafficcontroldevices,suchascones,

delineators,drums,verticalpanelsandbarricades,areusedtochannelve-hicleswhenatrafficlanemustbeused;

■ Beginlaneclosingsfarenoughinadvanceoftheworktoallowdriverstomovegraduallytoanewlane.Trafficflowisthennarrowedandre-directedintoanotherlane;

■ Makesureflaggersareclearlyvisibletoapproachingtrafficatalltimes.Theyshouldstandalonefarenoughinfrontoftheworkcrewtopermitaproperresponsebythemotoristtotheflagginginstructionsandtopermittraffictoreducespeedbeforeenteringtheworksite;

■ Ensurethatflaggers’signalsconformtoAmericanNationalStandardsInstitute(ANSI)anduniformtrafficcontrolstandards(ANSID6.1-1971).

FleetsafetyNooneshoulddriveanunsafevehicleordrivewithoutadequatetraining.Afleetsafetyprogramincludesvehiclemaintenanceandqualifieddrivers.

Checkvehiclesandmakenecessaryrepairsproblemsbeforeuse.Doaspotcheckforproblemsbeforedrivingthevehicle.Makesurebrakes,lights,tires,horn,wip-ers,mirrors,couplingdevicesandotherpartsareingoodworkingorder.Noteanyproblemswiththevehiclebeforereturningit.

yeesinvolvedinthesafetyprocess.Theyarebeneficialbecausetheyusework

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Chapter14Siteassessmentquestions

Duringfirstandsubsequentvisitstoaconstructionorfacilitymaintenanceloca-tion,thecomplianceofficer,thesite’ssafetyofficerorothercompetentpersonmayfindthefollowingquestionsuseful:

1. Isthecut,cavityordepressionatrenchoranexcavation?

�. Isthecut,cavityordepressionmorethan4feetdeep?

3. Istherewaterinthecut,cavityordepression?

4. Arethereadequatemeansofaccessandegress?

5. Arethereanysurfaceencumbrances?

6. Isthereexposuretovehiculartraffic?

7. Areadjacentstructuresstabilized?

8. Doesmobileequipmenthaveawarningsystem?

9. Isacompetentpersoninchargeoftheoperation?

10.Isequipmentoperatinginoraroundthecut,cavityordepression?

11.Areproceduresrequiredtomonitor,testandcontrolhazardous atmospheres?

1�.Doesacompetentpersondeterminesoiltype?

13.Wasasoiltestingdeviceusedtodeterminesoiltype?

14.Isthespoilplaced�feetormorefromtheedgeofthecut,cavityor depression?

15.Isthedepth�0feetormoreforthecut,cavityordepression?

16.Hasaregisteredprofessionalengineerapprovedtheprocedureifthedepthis morethan�0feet?

17.Doestheprocedurerequirebenchingormultiplebenching?

18.Doestheprocedurerequireshoringorshielding?

19.Ifprovided,doshieldsextendatleast18inchesabovethesurroundingareaif itisslopedtowardtheexcavation?

�0.Ifshieldsareused,isthedepthofthecutmorethantwofeetbelowthe bottomoftheshield?

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�1.Areanyrequiredsurfacecrossingsofthecut,cavityordepressionatthe properwidthandfittedwithhandrails?

��.Aremeansofegressfromthecut,cavityordepressionnomorethan�5feet fromthework?

�3.Isemergencyrescueequipmentrequired?

�4.Istheredocumentationoftheminimumdailyexcavationinspection?

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Chapter15Glossary

Acceptedengineeringpractices are procedures compatible with the standards of practice required of a registered professional engineer.

Adjacentstructurestability refers to the stability of the foundation(s) of adjacent structures whose location may create surcharges, changes in soil conditions or other disruptions that have the potential to extend into the failure zone of the exca-vation or trench.

Competentperson is an individual who is capable of identifying existing and pre-dictable hazards or working conditions that are hazardous, unsanitary or dangerous to employees, and who has authorization to take prompt corrective measures to eliminate or control these hazards and conditions.

Confinedspace is a space that, by design and/or configuration, has limited open-ings for entry and exit, has unfavorable natural ventilation, may contain or produce hazardous substances, and is not intended for continuous employee occupancy.

Excavation is any man-made cut, cavity, trench or depression in an earth surface that is formed by earth removal. A trench is a narrow excavation, in relation to its length, made below the surface of the ground. In general, the depth of a trench is greater than its width, and the width, measured at the bottom, is not greater than 15 feet or 4.6 meters. If a form or other structure installed or constructed in an excavation reduces the distance between the form and the side of the excavation to 15 feet or 4.6 meters or less as measured at the bottom of the excavation, the excavation is also considered to be a trench.

Hazardousatmosphere is an atmosphere that by reason of being explosive, flam-mable, poisonous, corrosive, oxidizing, irritating, oxygen-deficient, toxic or other-wise harmful may cause death, illness or injury to persons exposed to it.

Ingress and egress mean entry and exit, respectively. In trenching and excavation operations, they refer to the provision of safe means for employees to enter or exit an excavation or trench.

Protectivesystem refers to a method of protecting employees from cave-ins, from material that could fall or roll from an excavation face or into an excavation, and from the collapse of adjacent structures. Protective systems include support systems, sloping and benching systems, shield systems and other systems that provide the necessary protection.

Registeredprofessionalengineer is a person who is registered as a professional engineer in the state where the work is to be performed. However, a professional engineer who is registered in any state is deemed to be a “registered professional engineer” within the meaning of OSHA’s standard 29 CFR 1926 subpart P when approving designs for “manufactured protective systems” or “tabulated data” to be used in interstate commerce.

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Supportsystem refers to structures, such as underpinning, bracing and shoring that provide support to an adjacent structure, or underground installation or to the sides of an excavation or trench.

Subsurface encumbrances include underground utilities, foundations, streams, water tables, transformer vaults and geological anomalies.

Surcharge means an excessive vertical load or weight caused by spoil, overburden, vehicles, equipment or activities that may affect trench stability.

Tabulateddata are tables and charts approved by a registered professional engi-neer and used to design and construct a protective system.

Undergroundinstallations include, but are not limited to, utilities — sewer, tele-phone, fuel, electric, water and other product lines — tunnels, shafts, vaults, foundations and other underground fixtures, or equipment that may be encountered during excavation or trenching work.

Unconfinedcompressivestrength is the load per unit area at which soil will fail in compression. This measure can be determined by laboratory testing or it can be estimated in the field using a pocket penetrometer, thumb penetration tests or by other methods.