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  <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_SeniorUnsecuredNotesdue2029Member" abstract="true" name="SeniorUnsecuredNotesdue2029Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_CashPaymentsForInterestAndIncomeTaxesAbstract" abstract="true" name="CashPaymentsForInterestAndIncomeTaxesAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_AssetsNoncurrentExcludingPropertyPlantAndEquipment" abstract="false" name="AssetsNoncurrentExcludingPropertyPlantAndEquipment" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_CertainOtherThirdPartySitesMember" abstract="true" name="CertainOtherThirdPartySitesMember" 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_ClosureAndPostClosureLiabilitiesDomain" abstract="true" name="ClosureAndPostClosureLiabilitiesDomain" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_InterestExpenseNet" abstract="false" name="InterestExpenseNet" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_A2020AcquisitionsMember" abstract="true" name="A2020AcquisitionsMember" 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_RemedialLiabilitiesForInactiveSitesMember" abstract="true" name="RemedialLiabilitiesForInactiveSitesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SafetyKleenOilMember" abstract="true" name="SafetyKleenOilMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_VertexEnergyIncMember" abstract="true" name="VertexEnergyIncMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_LegalAndAdministrativeProceedingsMember" abstract="true" name="LegalAndAdministrativeProceedingsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForCurrencyTranslationAndOther" abstract="false" name="AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForCurrencyTranslationAndOther" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_ScheduleOfFiniteLivedAndIndefiniteLivedIntangibleAssetsTable" abstract="true" name="ScheduleOfFiniteLivedAndIndefiniteLivedIntangibleAssetsTable" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:hypercubeItem" type="xbrli:stringItemType"/>
  <xs:element id="clh_LossContingencyGeneralDamagesSoughtValue" abstract="false" name="LossContingencyGeneralDamagesSoughtValue" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_RemedialLiabilitiesIncludingSuperfundForNonLandfillOperationsMember" abstract="true" name="RemedialLiabilitiesIncludingSuperfundForNonLandfillOperationsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_A2021AcquisitionsMember" abstract="true" name="A2021AcquisitionsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_NonLandfillRetirementLiabilityMember" abstract="true" name="NonLandfillRetirementLiabilityMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_AccruedExpensesDisclosureTextBlock" abstract="false" name="AccruedExpensesDisclosureTextBlock" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:textBlockItemType"/>
  <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_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_UnbilledAccountsReceivableCurrent" abstract="false" name="UnbilledAccountsReceivableCurrent" nillable="true" xbrli:periodType="instant" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
