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  <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_AssetRetirementObligationPayments" abstract="false" name="AssetRetirementObligationPayments" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_RemedialLiabilitiesForLandfillSitesMember" abstract="true" name="RemedialLiabilitiesForLandfillSitesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_RemedialLiabilitiesIncludingSuperfundForNonLandfillOperationsMember" abstract="true" name="RemedialLiabilitiesIncludingSuperfundForNonLandfillOperationsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <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_AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForCurrencyTranslationAndOther" abstract="false" name="AccrualForEnvironmentalLossContingenciesIncreaseDecreaseForCurrencyTranslationAndOther" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_RemedialLiabilitiesForSuperfundSiteMember" abstract="true" name="RemedialLiabilitiesForSuperfundSiteMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_TermLoansMember" abstract="true" name="TermLoansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SeniorUnsecuredNotesdue2027Member" abstract="true" name="SeniorUnsecuredNotesdue2027Member" 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_SeniorUnsecuredNotesDue2031Member" abstract="true" name="SeniorUnsecuredNotesDue2031Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SecuredTermLoanMember" abstract="true" name="SecuredTermLoanMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_A2022SwapsMember" abstract="true" name="A2022SwapsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SeniorUnsecuredNotesDue2033Member" abstract="true" name="SeniorUnsecuredNotesDue2033Member" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_NewTermLoansMember" abstract="true" name="NewTermLoansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ExistingTermLoansMember" abstract="true" name="ExistingTermLoansMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_TermSOFRMember" abstract="true" name="TermSOFRMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_DebtInstrumentPurchasePricePercentage" abstract="false" name="DebtInstrumentPurchasePricePercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_DebtInstrumentRedemptionNoticePeriod" abstract="false" name="DebtInstrumentRedemptionNoticePeriod" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:durationItemType"/>
  <xs:element id="clh_DebtInstrumentPrepaymentPremiumPercentage" abstract="false" name="DebtInstrumentPrepaymentPremiumPercentage" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_DebtInstrumentInterestMargin" abstract="false" name="DebtInstrumentInterestMargin" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_NumeratorForBasicAndDilutedEarningsPerShareAbstract" abstract="true" name="NumeratorForBasicAndDilutedEarningsPerShareAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_DenominatorForBasicAndDilutedEarningsPerShareAbstract" abstract="true" name="DenominatorForBasicAndDilutedEarningsPerShareAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_NumberOfPerformanceStockAwardsThatPerformanceCriteriaNotAttained" abstract="false" name="NumberOfPerformanceStockAwardsThatPerformanceCriteriaNotAttained" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:sharesItemType"/>
  <xs:element id="clh_PerformanceStockAwardsMember" abstract="true" name="PerformanceStockAwardsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTargetPerformanceLevelPercentage" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsTargetPerformanceLevelPercentage" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPercentageOfTargetAward" abstract="false" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsPercentageOfTargetAward" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:percentItemType"/>
  <xs:element id="clh_ContingenciesByNatureOfContingencyAxis" abstract="true" name="ContingenciesByNatureOfContingencyAxis" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrldt:dimensionItem" type="xbrli:stringItemType"/>
  <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_LegalAndAdministrativeProceedingsMember" abstract="true" name="LegalAndAdministrativeProceedingsMember" 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_SuperfundProceedingsMember" abstract="true" name="SuperfundProceedingsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_ProductLiabilityCasesMember" abstract="true" name="ProductLiabilityCasesMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_SiteContingencyNumberOfSites" abstract="false" name="SiteContingencyNumberOfSites" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyNumberOfSitesOwnedByEntity" abstract="false" name="SiteContingencyNumberOfSitesOwnedByEntity" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyNumberOfSitesOwnedByThirdParty" abstract="false" name="SiteContingencyNumberOfSitesOwnedByThirdParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty" abstract="false" name="SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" abstract="false" name="SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" abstract="false" name="SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" nillable="true" xbrli:periodType="instant" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_NumberOfSitesPotentialLiabilityExceedsSubstantialQuota" abstract="false" name="NumberOfSitesPotentialLiabilityExceedsSubstantialQuota" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty" abstract="false" name="SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:integerItemType"/>
  <xs:element id="clh_ReportableSegmentsMember" abstract="true" name="ReportableSegmentsMember" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="dtr-types:domainItemType"/>
  <xs:element id="clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet" abstract="false" name="IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet" nillable="true" xbrli:periodType="duration" xbrli:balance="credit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
  <xs:element id="clh_ReconciliationOfNetIncomeToAdjustedEBITDAAbstract" abstract="true" name="ReconciliationOfNetIncomeToAdjustedEBITDAAbstract" nillable="true" xbrli:periodType="duration" substitutionGroup="xbrli:item" type="xbrli:stringItemType"/>
  <xs:element id="clh_CorporateCosts" abstract="false" name="CorporateCosts" nillable="true" xbrli:periodType="duration" xbrli:balance="debit" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType"/>
</xs:schema>
