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  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingLeaseLiabilitiesCurrent" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingLeaseLiabilitiesCurrent" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_FederalAndStateEnforcementActionsMember" abstract="true" name="FederalAndStateEnforcementActionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ScheduleOfFiniteLivedAndIndefiniteLivedIntangibleAssetsLineItems" abstract="true" name="ScheduleOfFiniteLivedAndIndefiniteLivedIntangibleAssetsLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAssetsAcquiredAndLiabilitiesAssumedNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_DerivativeFixedInterestRatePeriodTwoMember" abstract="true" name="DerivativeFixedInterestRatePeriodTwoMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_ContingencyNatureDomain" abstract="true" name="ContingencyNatureDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SiteContingencyNumberOfSitesWithIndemnifyingPartiesPayingAllCosts" abstract="false" name="SiteContingencyNumberOfSitesWithIndemnifyingPartiesPayingAllCosts" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyIndemnificationAgreementNumberOfSitesAcquired" abstract="false" name="SiteContingencyIndemnificationAgreementNumberOfSitesAcquired" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingLeaseRightOfUseAssets" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOperatingLeaseRightOfUseAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_DerivativeFixedInterestRatePeriodDomain" abstract="true" name="DerivativeFixedInterestRatePeriodDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_AssetRetirementObligationChangesRecordedInBalanceSheet" abstract="false" name="AssetRetirementObligationChangesRecordedInBalanceSheet" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLease" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLease" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_ClosureAndPostClosureLiabilitiesLineItems" abstract="true" name="ClosureAndPostClosureLiabilitiesLineItems" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings" abstract="false" name="NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_UnbilledAccountsReceivableCurrent" abstract="false" name="UnbilledAccountsReceivableCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLeaseLessCurrentPortion" abstract="false" name="BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOperatingLeaseLessCurrentPortion" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid" abstract="false" name="NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_LossContingencyRangeOfPossibleLossMinimum" abstract="false" name="LossContingencyRangeOfPossibleLossMinimum" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_OtherInventoriesMember" abstract="true" name="OtherInventoriesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ClosureAndPostClosureLiabilitiesTable" abstract="true" name="ClosureAndPostClosureLiabilitiesTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="clh_TermLoanAgreementMember" abstract="true" name="TermLoanAgreementMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_OperatingSegmentsAndCorporateNonSegmentMember" abstract="true" name="OperatingSegmentsAndCorporateNonSegmentMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SeniorUnsecuredNotesdue2029Member" abstract="true" name="SeniorUnsecuredNotesdue2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_IndustrialServicesAndOtherMember" abstract="true" name="IndustrialServicesAndOtherMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_RemedialLiabilityAssumedInAcquisitionOfPropertyPlantAndEquipment" abstract="false" name="RemedialLiabilityAssumedInAcquisitionOfPropertyPlantAndEquipment" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_NumberOfSitesPotentialLiabilityExceedsSubstantialQuota" abstract="false" name="NumberOfSitesPotentialLiabilityExceedsSubstantialQuota" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_AssetRetirementObligationPayments" abstract="false" name="AssetRetirementObligationPayments" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilities" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredTaxLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_AssetRetirementObligationsDiscountRate" abstract="false" name="AssetRetirementObligationsDiscountRate" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_HydroChemPSCMember" abstract="true" name="HydroChemPSCMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ClosureAndPostClosureLiabilitiesAxis" abstract="true" name="ClosureAndPostClosureLiabilitiesAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <xs:element id="clh_AccruedCappingClosurePostClosureAndRemedialLiabilitiesCurrent" abstract="false" name="AccruedCappingClosurePostClosureAndRemedialLiabilitiesCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_DeferredContractCostRecognitionPeriod" abstract="false" name="DeferredContractCostRecognitionPeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="clh_TechnicalServicesMember" abstract="true" name="TechnicalServicesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_BuildingsAndImprovemensMember" abstract="true" name="BuildingsAndImprovemensMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_NumberOfPerformanceStockAwardsThatPerformanceCriteriaNotAttained" abstract="false" name="NumberOfPerformanceStockAwardsThatPerformanceCriteriaNotAttained" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="clh_LandfillRetirementLiabilityMember" abstract="true" name="LandfillRetirementLiabilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_AccretionOfEnvironmentalLiabilities" abstract="false" name="AccretionOfEnvironmentalLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentLiabilities" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentCurrentLiabilities" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_AccrualForEnvironmentalLossContingenciesMeasurementPeriodAdjustmentFromAPriorPeriodAcquisition" abstract="false" name="AccrualForEnvironmentalLossContingenciesMeasurementPeriodAdjustmentFromAPriorPeriodAcquisition" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" abstract="false" name="FiniteLivedIntangibleAssetExpectedAmortizationAfterYearFour" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_AssetRetirementObligationChangesRecordedInStatementOfIncome" abstract="false" name="AssetRetirementObligationChangesRecordedInStatementOfIncome" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_March272021AcquisitionMember" abstract="true" name="March272021AcquisitionMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPrepaidExpensesAndOtherCurrentAssets" abstract="false" name="BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPrepaidExpensesAndOtherCurrentAssets" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
