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    <link:label id="lab_clh_EnvironmentalContingenciesTable_1FE13AA6A17CBFBFDABE45B1F19D0DB3_label_en-US" xlink:label="lab_clh_EnvironmentalContingenciesTable_1FE13AA6A17CBFBFDABE45B1F19D0DB3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Environmental Contingencies [Table]</link:label>
    <link:label id="lab_clh_EnvironmentalContingenciesTable_1FE13AA6A17CBFBFDABE45B1F19D0DB3_documentation_en-US" xlink:label="lab_clh_EnvironmentalContingenciesTable_1FE13AA6A17CBFBFDABE45B1F19D0DB3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Discloses the specific components (such as the nature, name, and date) of the environmental contingencies and gives the possible estimates, or states that a reasonable estimate cannot be made.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_EnvironmentalContingenciesTable" xlink:label="loc_clh_EnvironmentalContingenciesTable_1FE13AA6A17CBFBFDABE45B1F19D0DB3" xlink:type="locator" />
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    <link:label id="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906_terseLabel_en-US" xlink:label="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Contingencies by Nature of Contingency [Axis]</link:label>
    <link:label id="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906_label_en-US" xlink:label="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Contingencies by Nature of Contingency [Axis]</link:label>
    <link:label id="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906_documentation_en-US" xlink:label="lab_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Quantifies and describes each contingency that exists as of the balance sheet date, by nature of the probable or possible estimates.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_ContingenciesByNatureOfContingencyAxis" xlink:label="loc_clh_ContingenciesByNatureOfContingencyAxis_0BEF00E0B1F6570D554945B1F19DF906" xlink:type="locator" />
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    <link:label id="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E_terseLabel_en-US" xlink:label="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Contingency Nature [Domain]</link:label>
    <link:label id="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E_label_en-US" xlink:label="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Contingency Nature [Domain]</link:label>
    <link:label id="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E_documentation_en-US" xlink:label="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">An existing condition, situation, or a set of circumstances, which involve uncertainty as to the possible outcomes to an enterprise that will ultimately be resolved, when one or more future events occur or fail to occur. Resolution of the uncertainty may confirm the incurrence of a loss or profit or the incurrence of a liability.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_ContingencyNatureDomain" xlink:label="loc_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:to="lab_clh_ContingencyNatureDomain_76BD17EFE4F34156B03545B1F1A3229E" xlink:type="arc" />
    <link:label id="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8_terseLabel_en-US" xlink:label="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Legal and Administrative Proceedings</link:label>
    <link:label id="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8_label_en-US" xlink:label="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Legal and Administrative Proceedings [Member]</link:label>
    <link:label id="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8_documentation_en-US" xlink:label="lab_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the actual or potential liabilities that are related to the legal and administrative proceedings.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LegalAndAdministrativeProceedingsMember" xlink:label="loc_clh_LegalAndAdministrativeProceedingsMember_8B52FDEE8AB8B79CF01A45B1F1A3A1E8" xlink:type="locator" />
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    <link:label id="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4_terseLabel_en-US" xlink:label="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Ville Mercier</link:label>
    <link:label id="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4_label_en-US" xlink:label="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Ville Mercier [Member]</link:label>
    <link:label id="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4_documentation_en-US" xlink:label="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the details that pertain to the Ville Mercier.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_VilleMercierMember" xlink:label="loc_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:to="lab_clh_VilleMercierMember_808434B6315166EECF9F45B1F1A3CCE4" xlink:type="arc" />
    <link:label id="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77_terseLabel_en-US" xlink:label="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Superfund Proceedings</link:label>
    <link:label id="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77_label_en-US" xlink:label="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Superfund Proceedings [Member]</link:label>
    <link:label id="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77_documentation_en-US" xlink:label="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the indemnification obligations under federal or state Superfund laws.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SuperfundProceedingsMember" xlink:label="loc_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:to="lab_clh_SuperfundProceedingsMember_66E2940364390F356C1645B1F1A44E77" xlink:type="arc" />
    <link:label id="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1_terseLabel_en-US" xlink:label="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">ChemWaste</link:label>
    <link:label id="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1_label_en-US" xlink:label="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Certain Other Third Party Sites [member]</link:label>
    <link:label id="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1_documentation_en-US" xlink:label="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the details that pertain to Certain Other Third Party Sites.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_CertainOtherThirdPartySitesMember" xlink:label="loc_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:to="lab_clh_CertainOtherThirdPartySitesMember_66ADF1E45F437AE76B7445B1F1A452B1" xlink:type="arc" />
    <link:label id="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2_terseLabel_en-US" xlink:label="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Kleen Performance Products</link:label>
    <link:label id="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2_label_en-US" xlink:label="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Kleen Performance Products [Member]</link:label>
    <link:label id="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2_documentation_en-US" xlink:label="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Kleen Performance Products</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_KleenPerformanceProductsMember" xlink:label="loc_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:to="lab_clh_KleenPerformanceProductsMember_9ADB9BCC06FBBFD5397F45B1F1A45BE2" xlink:type="arc" />
    <link:label id="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73_terseLabel_en-US" xlink:label="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Federal and State Enforcement Actions</link:label>
    <link:label id="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73_label_en-US" xlink:label="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Federal and State Enforcement Actions [Member]</link:label>
    <link:label id="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73_documentation_en-US" xlink:label="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The regulatory proceedings that are relating primarily to waste treatment, storage or disposal facilities.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_FederalAndStateEnforcementActionsMember" xlink:label="loc_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:to="lab_clh_FederalAndStateEnforcementActionsMember_B480EB8696384B70D38145B1F1A4BD73" xlink:type="arc" />
    <link:label id="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC_terseLabel_en-US" xlink:label="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Contingencies [Line Items]</link:label>
    <link:label id="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC_label_en-US" xlink:label="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Contingencies [Line Items]</link:label>
    <link:label id="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC_documentation_en-US" xlink:label="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">-- None. No documentation exists for this element. --</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_ContingenciesLineItems" xlink:label="loc_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:to="lab_clh_ContingenciesLineItems_136F3C9D19F98BEFE48C45B1F1A621EC" xlink:type="arc" />
    <link:label id="lab_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Recorded reserves for actual or probable liabilities</link:label>
    <link:label id="lab_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34_label_en-US" xlink:label="lab_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency Accrual</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyAccrualAtCarryingValue" xlink:label="loc_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34" xlink:to="lab_us-gaap_LossContingencyAccrualAtCarryingValue_8EB34D8E4FD731BA5FDD45B1F1A61A34" xlink:type="arc" />
    <link:label id="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5_terseLabel_en-US" xlink:label="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Possible increase in legal and administrative proceedings</link:label>
    <link:label id="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5_label_en-US" xlink:label="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency Accrual at Carrying Value Potential Additional Liability</link:label>
    <link:label id="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5_documentation_en-US" xlink:label="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The amount as of the balance sheet date of potential needed increase in the loss contingency reserves.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability" xlink:label="loc_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:to="lab_clh_LossContingencyAccrualAtCarryingValuePotentialAdditionalLiability_9F5588D9FCECD365109545B1F1A6FEC5" xlink:type="arc" />
    <link:label id="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5_terseLabel_en-US" xlink:label="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of permits issued by government, for dumping organic liquid</link:label>
    <link:label id="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5_label_en-US" xlink:label="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number of Permits Issued by Government to Dump Organic Liquid</link:label>
    <link:label id="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5_documentation_en-US" xlink:label="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of permits that are granted by the government in relation to environmental liabilities.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid" xlink:label="loc_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:to="lab_clh_NumberOfPermitsIssuedByGovernmentToDumpOrganicLiquid_2D49876687FFE853372645B1F1A70BA5" xlink:type="arc" />
    <link:label id="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882_terseLabel_en-US" xlink:label="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of neighboring municipalities filing separate legal proceedings against the Mercier Subsidiary and the Government of Quebec</link:label>
    <link:label id="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882_label_en-US" xlink:label="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number of Neighboring Municipalities Filing Separate Legal Proceedings</link:label>
    <link:label id="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882_documentation_en-US" xlink:label="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the number of municipalities other than Ville Mercier that filed legal proceedings against the Mercier Subsidiary.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings" xlink:label="loc_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:to="lab_clh_NumberOfNeighboringMunicipalitiesFilingSeparateLegalProceedings_FE341A2DF74131A164C445B1F1A75882" xlink:type="arc" />
    <link:label id="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B_terseLabel_en-US" xlink:label="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">General damages sought</link:label>
    <link:label id="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B_label_en-US" xlink:label="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency, General Damages Sought, Value</link:label>
    <link:label id="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B_documentation_en-US" xlink:label="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Loss Contingency, General Damages Sought, Value</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LossContingencyGeneralDamagesSoughtValue" xlink:label="loc_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:to="lab_clh_LossContingencyGeneralDamagesSoughtValue_B2B1C00BBECE956E2BF845B1F1A74F1B" xlink:type="arc" />
    <link:label id="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860_terseLabel_en-US" xlink:label="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Punitive damages sought</link:label>
    <link:label id="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860_label_en-US" xlink:label="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency, Punitive Damages Sought, Value</link:label>
    <link:label id="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860_documentation_en-US" xlink:label="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Loss Contingency, Punitive Damages Sought, Value</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LossContingencyPunitiveDamagesSoughtValue" xlink:label="loc_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:to="lab_clh_LossContingencyPunitiveDamagesSoughtValue_2E231877C1B2C033274045B1F1A78860" xlink:type="arc" />
    <link:label id="lab_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of proceedings as defendant</link:label>
    <link:label id="lab_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071_label_en-US" xlink:label="lab_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency, Pending Claims, Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyPendingClaimsNumber" xlink:label="loc_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071" xlink:to="lab_us-gaap_LossContingencyPendingClaimsNumber_79CDCF3B50F06DD9164E45B1F1A73071" xlink:type="arc" />
    <link:label id="lab_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of product liability claims settled or dismissed</link:label>
    <link:label id="lab_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9_label_en-US" xlink:label="lab_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency, Claims Settled and Dismissed, Number</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyClaimsSettledAndDismissedNumber" xlink:label="loc_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9" xlink:to="lab_us-gaap_LossContingencyClaimsSettledAndDismissedNumber_9F4A9E60180152F480C645B1F1A78BD9" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174_totalLabel_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Number of sites owned by third party excluded from cleanup or related liabilities</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174_label_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Number of Sites</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174_documentation_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites that are subject to proceedings under federal or state superfund laws brought against the company or against third parties for which the company may have certain indemnification obligations.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyNumberOfSites" xlink:label="loc_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:to="lab_clh_SiteContingencyNumberOfSites_E4194AFF82ED4F8E434945B1F1A8C174" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of sites owned by the entity subject to proceedings under federal or state superfund laws</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D_label_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Number of Sites Owned by Entity</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D_documentation_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites that are subject to proceedings under federal or state superfund laws that are owned by the entity.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyNumberOfSitesOwnedByEntity" xlink:label="loc_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:to="lab_clh_SiteContingencyNumberOfSitesOwnedByEntity_F982EDA368194E1A6B5845B1F1A8145D" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A_totalLabel_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Number of sites owned by third parties</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A_label_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A_documentation_en-US" xlink:label="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites owned by third parties subject to proceedings under federal or state Superfund laws for which the company or the prior owners shipped wastes.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:to="lab_clh_SiteContingencyNumberOfSitesOwnedByThirdParty_B32FB7927FF3A23D724045B1F1A87D0A" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of sites for which environmental remediation expense is settled</link:label>
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58_label_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Environmental Remediation Expense Settled Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58_documentation_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites owned by the third party for which environmental remediation expense is settled.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:to="lab_clh_SiteContingencyEnvironmentalRemediationExpenseSettledNumberOfSitesOwnedByThirdParty_EDC81349F88AAF76C37645B1F1A8EC58" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Third party sites requiring expenditure on remediation</link:label>
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C_label_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Environmental Remediation Expense Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C_documentation_en-US" xlink:label="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites for which environmental remediation expense is incurred subject to proceedings under federal or state superfund laws owned by third party.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:to="lab_clh_SiteContingencyEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_0F3C754834E96A942D7145B1F1A8423C" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of sites not currently requiring expenditures on remediation</link:label>
    <link:label id="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85_label_en-US" xlink:label="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Not Requiring Environmental Remediation Expense Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85_documentation_en-US" xlink:label="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites owned by the third party for which environmental remediation expense is not required.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:to="lab_clh_SiteContingencyNotRequiringEnvironmentalRemediationExpenseNumberOfSitesOwnedByThirdParty_9BE6D8E2A0321D5F639A45B1F1A80D85" xlink:type="arc" />
    <link:label id="lab_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E_terseLabel_en-US" xlink:label="lab_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Minimum potential liability</link:label>
    <link:label id="lab_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E_label_en-US" xlink:label="lab_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Loss Contingency, Estimate of Possible Loss</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E" xlink:to="lab_us-gaap_LossContingencyEstimateOfPossibleLoss_0CEE667245C979C0AB1E45B1F1A8711E" xlink:type="arc" />
    <link:label id="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785_terseLabel_en-US" xlink:label="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Number of sites which potential liability could exceed $100,000</link:label>
    <link:label id="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785_label_en-US" xlink:label="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Number of Sites, Potential Liability Exceeds Substantial Quota</link:label>
    <link:label id="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785_documentation_en-US" xlink:label="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Number of Sites, Potential Liability Exceeds Substantial Quota</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota" xlink:label="loc_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:to="lab_clh_NumberofSitesPotentialLiabilityExceedsSubstantialQuota_D65048F8D0F1E6A0E98D45B1F1A94785" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Indemnification agreement with third party sites</link:label>
    <link:label id="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95_label_en-US" xlink:label="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Indemnification Agreement Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95_documentation_en-US" xlink:label="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of sites for which the company has an indemnification agreement from the third party seller.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:to="lab_clh_SiteContingencyIndemnificationAgreementNumberOfSitesOwnedByThirdParty_C39D0932B55DDDED926445B1F1A99C95" xlink:type="arc" />
    <link:label id="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543_terseLabel_en-US" xlink:label="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Notices received from owners of third parties sites seeking indemnifications from the company</link:label>
    <link:label id="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543_label_en-US" xlink:label="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency, Notice Received Number of Sites Owned by Third Party</link:label>
    <link:label id="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543_documentation_en-US" xlink:label="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The number of notices received from owners of third party sites related to the CSD assets seeking indemnification from the company.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty" xlink:label="loc_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:to="lab_clh_SiteContingencyNoticeReceivedNumberOfSitesOwnedByThirdParty_C52DBD03CEFF19782C3F45B1F1A98543" xlink:type="arc" />
    <link:label id="lab_us-gaap_AccruedInsuranceCurrent_2A45C2D7C879CC7632D03D55BF4A47D0_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedInsuranceCurrent_33766F6E83595987A23908FEC5E2E61B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Insurance</link:label>
    <link:label id="lab_us-gaap_AccruedInsuranceCurrent_2A45C2D7C879CC7632D03D55BF4A47D0_label_en-US" xlink:label="lab_us-gaap_AccruedInsuranceCurrent_33766F6E83595987A23908FEC5E2E61B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Accrued Insurance, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedInsuranceCurrent" xlink:label="loc_us-gaap_AccruedInsuranceCurrent_33766F6E83595987A23908FEC5E2E61B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_InterestPayableCurrent_5EB88962D011DCA02DF93D55BF4B9498_terseLabel_en-US" xlink:label="lab_us-gaap_InterestPayableCurrent_522904FFBECB5D108353C7D3CD838245" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Interest</link:label>
    <link:label id="lab_us-gaap_InterestPayableCurrent_5EB88962D011DCA02DF93D55BF4B9498_label_en-US" xlink:label="lab_us-gaap_InterestPayableCurrent_522904FFBECB5D108353C7D3CD838245" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Interest Payable, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPayableCurrent" xlink:label="loc_us-gaap_InterestPayableCurrent_522904FFBECB5D108353C7D3CD838245" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_07608B370C9BA17B2E803D55BF4B958D_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_A18EEE33F73B5C97962E8844ABD0623F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Accrued compensation and benefits</link:label>
    <link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_07608B370C9BA17B2E803D55BF4B958D_label_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_A18EEE33F73B5C97962E8844ABD0623F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Employee-related Liabilities, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_A18EEE33F73B5C97962E8844ABD0623F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_A18EEE33F73B5C97962E8844ABD0623F" xlink:to="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_A18EEE33F73B5C97962E8844ABD0623F" xlink:type="arc" />
    <link:label id="lab_us-gaap_TaxesPayableCurrent_D3741B55F367D4D4088F3D55BF4C94DD_terseLabel_en-US" xlink:label="lab_us-gaap_TaxesPayableCurrent_972DDF03FE0759E8BC19000FED7F8D0F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Income, real estate, sales and other taxes</link:label>
    <link:label id="lab_us-gaap_TaxesPayableCurrent_D3741B55F367D4D4088F3D55BF4C94DD_label_en-US" xlink:label="lab_us-gaap_TaxesPayableCurrent_972DDF03FE0759E8BC19000FED7F8D0F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Taxes Payable, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_TaxesPayableCurrent" xlink:label="loc_us-gaap_TaxesPayableCurrent_972DDF03FE0759E8BC19000FED7F8D0F" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_9E9FEB35B7EF3921499D3D55BF4CC9D4_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent_5E2826DBD5D85397AB7C354DFCCFC265" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other</link:label>
    <link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_9E9FEB35B7EF3921499D3D55BF4CC9D4_label_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent_5E2826DBD5D85397AB7C354DFCCFC265" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Accrued Liabilities, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_5E2826DBD5D85397AB7C354DFCCFC265" xlink:type="locator" />
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    <link:label id="lab_us-gaap_AccruedLiabilitiesCurrent_D30F95EED97379E899C93D55BF4C2F46_totalLabel_en-US" xlink:label="lab_us-gaap_AccruedLiabilitiesCurrent_1D099E5270C95FDC9747FA868F550342" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total accrued expenses</link:label>
    <link:label id="lab_us-gaap_AccruedLiabilitiesCurrent_D30F95EED97379E899C93D55BF4C2F46_label_en-US" xlink:label="lab_us-gaap_AccruedLiabilitiesCurrent_1D099E5270C95FDC9747FA868F550342" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Accrued Liabilities, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccruedLiabilitiesCurrent_1D099E5270C95FDC9747FA868F550342" xlink:type="locator" />
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    <link:label id="lab_us-gaap_StatementOfStockholdersEquityAbstract_0ADC54EAAAF7F3905DA22221E26450FF_label_en-US" xlink:label="lab_us-gaap_StatementOfStockholdersEquityAbstract_0ADC54EAAAF7F3905DA22221E26450FF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Statement of Stockholders' Equity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementOfStockholdersEquityAbstract" xlink:label="loc_us-gaap_StatementOfStockholdersEquityAbstract_0ADC54EAAAF7F3905DA22221E26450FF" xlink:type="locator" />
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    <link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_5F9943FD59B58E4447C32221E2682CAB_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare_5F9943FD59B58E4447C32221E2682CAB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Common stock, par value (in USD per share)</link:label>
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    <link:label id="lab_us-gaap_EarningsPerShareAbstract_F11ABE37A30BF357790C4209DBD586B2_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract_F11ABE37A30BF357790C4209DBD586B2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Earnings Per Share [Abstract]</link:label>
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    <link:label id="lab_us-gaap_ServiceMember_71E8EA3FEFBF0B4CBE8065DB6B27B114_label_en-US" xlink:label="lab_us-gaap_ServiceMember_71E8EA3FEFBF0B4CBE8065DB6B27B114" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Service [Member]</link:label>
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    <link:label id="lab_us-gaap_ProductMember_BD3C81BAB70BE0F91E5E65DB6B2759AB_terseLabel_en-US" xlink:label="lab_us-gaap_ProductMember_BD3C81BAB70BE0F91E5E65DB6B2759AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Product</link:label>
    <link:label id="lab_us-gaap_ProductMember_BD3C81BAB70BE0F91E5E65DB6B2759AB_label_en-US" xlink:label="lab_us-gaap_ProductMember_BD3C81BAB70BE0F91E5E65DB6B2759AB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Product [Member]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProductMember" xlink:label="loc_us-gaap_ProductMember_BD3C81BAB70BE0F91E5E65DB6B2759AB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_StatementLineItems_A5D804CD539A0028B87565DB6B2848C5_terseLabel_en-US" xlink:label="lab_us-gaap_StatementLineItems_A5D804CD539A0028B87565DB6B2848C5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Statement [Line Items]</link:label>
    <link:label id="lab_us-gaap_StatementLineItems_A5D804CD539A0028B87565DB6B2848C5_label_en-US" xlink:label="lab_us-gaap_StatementLineItems_A5D804CD539A0028B87565DB6B2848C5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Statement [Line Items]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_A5D804CD539A0028B87565DB6B2848C5" xlink:type="locator" />
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    <link:label id="lab_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E_terseLabel_en-US" xlink:label="lab_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Revenues:</link:label>
    <link:label id="lab_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E_label_en-US" xlink:label="lab_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Revenues [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E" xlink:to="lab_us-gaap_RevenuesAbstract_5476A03889F4BBD5A5FA65DB6B285C1E" xlink:type="arc" />
    <link:label id="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_D8227838DF558AA75FD065DB6B28DED9_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_D8227838DF558AA75FD065DB6B28DED9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total revenues</link:label>
    <link:label id="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_D8227838DF558AA75FD065DB6B28DED9_label_en-US" xlink:label="lab_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_D8227838DF558AA75FD065DB6B28DED9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Revenue from Contract with Customer, Excluding Assessed Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_D8227838DF558AA75FD065DB6B28DED9" xlink:type="locator" />
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    <link:label id="lab_us-gaap_CostOfRevenueAbstract_AA6575D79BD8F02E761D65DB6B286DCD_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfRevenueAbstract_AA6575D79BD8F02E761D65DB6B286DCD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cost of revenues: (exclusive of items shown separately below)</link:label>
    <link:label id="lab_us-gaap_CostOfRevenueAbstract_AA6575D79BD8F02E761D65DB6B286DCD_label_en-US" xlink:label="lab_us-gaap_CostOfRevenueAbstract_AA6575D79BD8F02E761D65DB6B286DCD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cost of Revenue [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfRevenueAbstract" xlink:label="loc_us-gaap_CostOfRevenueAbstract_AA6575D79BD8F02E761D65DB6B286DCD" xlink:type="locator" />
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    <link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_C991BB0B2434F4D8DCD665DB6B28EE9A_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold_C991BB0B2434F4D8DCD665DB6B28EE9A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total cost of revenues</link:label>
    <link:label id="lab_us-gaap_CostOfGoodsAndServicesSold_C991BB0B2434F4D8DCD665DB6B28EE9A_label_en-US" xlink:label="lab_us-gaap_CostOfGoodsAndServicesSold_C991BB0B2434F4D8DCD665DB6B28EE9A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cost of Goods and Services Sold</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_C991BB0B2434F4D8DCD665DB6B28EE9A" xlink:type="locator" />
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    <link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_ADC98547560432D286DB65DB6B2E8E95_terseLabel_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense_ADC98547560432D286DB65DB6B2E8E95" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Selling, general and administrative expenses</link:label>
    <link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_ADC98547560432D286DB65DB6B2E8E95_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense_ADC98547560432D286DB65DB6B2E8E95" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Selling, General and Administrative Expense</link:label>
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    <link:label id="lab_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C_terseLabel_en-US" xlink:label="lab_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Accretion of environmental liabilities</link:label>
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    <link:label id="lab_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C_documentation_en-US" xlink:label="lab_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element includes accretion expenditure that pertains to asset retirement obligations and environmental remediation.</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C" xlink:to="lab_clh_AccretionOfEnvironmentalLiabilities_3D0788831DB7A65C0AED65DB6B2E031C" xlink:type="arc" />
    <link:label id="lab_us-gaap_DepreciationDepletionAndAmortization_F97D02B9485DE82FEF6465DB6B2ED590_terseLabel_en-US" xlink:label="lab_us-gaap_DepreciationDepletionAndAmortization_F97D02B9485DE82FEF6465DB6B2ED590" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Depreciation and amortization</link:label>
    <link:label id="lab_us-gaap_DepreciationDepletionAndAmortization_F97D02B9485DE82FEF6465DB6B2ED590_label_en-US" xlink:label="lab_us-gaap_DepreciationDepletionAndAmortization_F97D02B9485DE82FEF6465DB6B2ED590" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Depreciation, Depletion and Amortization</link:label>
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    <link:label id="lab_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Income from operations</link:label>
    <link:label id="lab_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24_label_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Income (Loss)</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24" xlink:to="lab_us-gaap_OperatingIncomeLoss_C6F6912569995B300F4965DB6B2F6C24" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28_terseLabel_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other income (expense), net</link:label>
    <link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28_label_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Nonoperating Income (Expense)</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28" xlink:to="lab_us-gaap_OtherNonoperatingIncomeExpense_B85B5DCFCADFE7A72B3165DB6B2F6E28" xlink:type="arc" />
    <link:label id="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_858EEAEBF2EE1F271A4365DB6B2F2F84_netLabel_en-US" xlink:label="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_858EEAEBF2EE1F271A4365DB6B2F2F84" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:type="resource" xml:lang="en-US">Interest expense, net of interest income of $926 and $764, respectively</link:label>
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    <link:label id="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_E37F03484CEFD82800EC65DB67F57F12_terseLabel_en-US" xlink:label="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_E37F03484CEFD82800EC65DB67F57F12" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Interest (expense) income, net</link:label>
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    <link:label id="lab_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C_label_en-US" xlink:label="lab_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Income (Loss) from Affiliates Subsidiaries and Holding Company</link:label>
    <link:label id="lab_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C_documentation_en-US" xlink:label="lab_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the income (loss) from affiliates, subsidiaries and the holding company.</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C" xlink:to="lab_clh_IncomeLossFromAffiliatesSubsidiariesAndHoldingCompany_25E31372EB35FD9BDC4165DB67F5ED8C" xlink:type="arc" />
    <link:label id="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4_terseLabel_en-US" xlink:label="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intercompany interest income (expense)</link:label>
    <link:label id="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4_label_en-US" xlink:label="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Net Interest Income from Affiliates Subsidiaries and Holding Company</link:label>
    <link:label id="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4_documentation_en-US" xlink:label="lab_clh_NetInterestIncomeFromAffiliatesSubsidiariesAndHoldingCompany_CBB94040DAD2378F4C3465DB67F592D4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Represents the net interest income from affiliates, subsidiaries and the holding company.</link:label>
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    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2968B3DBBFB511A10FCF65DB67F609CB_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_2968B3DBBFB511A10FCF65DB67F609CB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other comprehensive income</link:label>
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    <link:label id="lab_clh_ScheduleOfSegmentRevenuesTableTextBlock_863C884F4426D7CACAFA45B1F123DF0B_terseLabel_en-US" xlink:label="lab_clh_ScheduleOfSegmentRevenuesTableTextBlock_863C884F4426D7CACAFA45B1F123DF0B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Reconciliation of third party revenues to direct revenues</link:label>
    <link:label id="lab_clh_ScheduleOfSegmentRevenuesTableTextBlock_863C884F4426D7CACAFA45B1F123DF0B_label_en-US" xlink:label="lab_clh_ScheduleOfSegmentRevenuesTableTextBlock_863C884F4426D7CACAFA45B1F123DF0B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Schedule of Segment Revenues [Table Text Block]</link:label>
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    <link:loc xlink:href="clh-20190331.xsd#clh_ScheduleOfSegmentRevenuesTableTextBlock" xlink:label="loc_clh_ScheduleOfSegmentRevenuesTableTextBlock_863C884F4426D7CACAFA45B1F123DF0B" xlink:type="locator" />
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    <link:loc xlink:href="clh-20190331.xsd#clh_ScheduleOfReconciliationOfNetIncomeToAdjustedEarningsBeforeInterestTaxDepreciationAndAmortizationConsolidatedTableTextBlock" xlink:label="loc_clh_ScheduleOfReconciliationOfNetIncomeToAdjustedEarningsBeforeInterestTaxDepreciationAndAmortizationConsolidatedTableTextBlock_DB84F86BF13847E4164545B1F123AC4D" xlink:type="locator" />
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    <link:label id="lab_clh_ScheduleOfPropertyPlantAndEquipmentIntangibleAssetsAndTotalAssetsBySegmentTableTextBlock_DEE05F97FB8248C1B89145B1F1299DB6_terseLabel_en-US" xlink:label="lab_clh_ScheduleOfPropertyPlantAndEquipmentIntangibleAssetsAndTotalAssetsBySegmentTableTextBlock_DEE05F97FB8248C1B89145B1F1299DB6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">PP&amp;E, intangible assets and total assets by segment</link:label>
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    <link:loc xlink:href="clh-20190331.xsd#clh_ScheduleOfPropertyPlantAndEquipmentIntangibleAssetsAndTotalAssetsBySegmentTableTextBlock" xlink:label="loc_clh_ScheduleOfPropertyPlantAndEquipmentIntangibleAssetsAndTotalAssetsBySegmentTableTextBlock_DEE05F97FB8248C1B89145B1F1299DB6" xlink:type="locator" />
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    <link:label id="lab_clh_ScheduleOfSegmentTotalAssetsTableTextBlock_46321060B137E9DC905245B1F129AB8B_terseLabel_en-US" xlink:label="lab_clh_ScheduleOfSegmentTotalAssetsTableTextBlock_46321060B137E9DC905245B1F129AB8B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Schedule of assets by reported segment</link:label>
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    <link:loc xlink:href="clh-20190331.xsd#clh_ScheduleOfSegmentTotalAssetsTableTextBlock" xlink:label="loc_clh_ScheduleOfSegmentTotalAssetsTableTextBlock_46321060B137E9DC905245B1F129AB8B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating Leases</link:label>
    <link:label id="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724_label_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating Lease Liabilities, Payments Due [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract" xlink:label="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724" xlink:to="lab_us-gaap_OperatingLeaseLiabilitiesPaymentsDueAbstract_38ED0E1FE3E3EB4F51C85531C9B4D724" xlink:type="arc" />
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019 (remaining nine months)</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Remainder of Fiscal Year</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsRemainderOfFiscalYear_A821A5EED543F88283C55531C9B562FA" xlink:type="arc" />
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Two</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearTwo_09F4A962728C6CB2E8945531C9B5AE1F" xlink:type="arc" />
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2021</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearThree_39DC2839C25A66F73E845531C9B50B60" xlink:type="arc" />
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2022</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFour_A4152173618FC8CE82BF5531C9B60380" xlink:type="arc" />
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C_terseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2023</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C" xlink:to="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDueYearFive_72B16F62EF65B6869AEB5531C9B6388C" xlink:type="arc" />
    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2_terseLabel_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2024</link:label>
    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2_label_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Six</link:label>
    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2_documentation_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due Year Six</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix" xlink:label="loc_clh_LesseeOperatingLeaseLiabilityPaymentsDueYearSix_F2B97230CBFF70AF2FC35531C9B61CC2" xlink:type="locator" />
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    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B_terseLabel_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Thereafter</link:label>
    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B_label_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due after Year Six</link:label>
    <link:label id="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B_documentation_en-US" xlink:label="lab_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due after Year Six</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix" xlink:label="loc_clh_LesseeOperatingLeaseLiabilityPaymentsDueafterYearSix_40DC392AC8C2C1E477E85531C9B6314B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0766FEF4CF834C0B1D725531C9B60AF1_totalLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0766FEF4CF834C0B1D725531C9B60AF1" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total future lease payments</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0766FEF4CF834C0B1D725531C9B60AF1_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0766FEF4CF834C0B1D725531C9B60AF1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Payments, Due</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityPaymentsDue_0766FEF4CF834C0B1D725531C9B60AF1" xlink:type="locator" />
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    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_514458C3B878450E80A85531C9B7A307_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_514458C3B878450E80A85531C9B7A307" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Amount representing interest</link:label>
    <link:label id="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_514458C3B878450E80A85531C9B7A307_label_en-US" xlink:label="lab_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_514458C3B878450E80A85531C9B7A307" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Lessee, Operating Lease, Liability, Undiscounted Excess Amount</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_us-gaap_LesseeOperatingLeaseLiabilityUndiscountedExcessAmount_514458C3B878450E80A85531C9B7A307" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OperatingLeaseLiability_26E44F063FAC246C74825531C9B7ACDD_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiability_26E44F063FAC246C74825531C9B7ACDD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total lease liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OperatingLeaseLiability" xlink:label="loc_us-gaap_OperatingLeaseLiability_26E44F063FAC246C74825531C9B7ACDD" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_F6E55D954D38DD1D42955531C9B79348_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_F6E55D954D38DD1D42955531C9B79348" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Finance Lease</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_F6E55D954D38DD1D42955531C9B79348_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_F6E55D954D38DD1D42955531C9B79348" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease Liabilities, Payments, Due [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract" xlink:label="loc_us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract_F6E55D954D38DD1D42955531C9B79348" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_CCDF1698D7C0B45DDD3C5531C9B7A552_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsRemainderOfFiscalYear_CCDF1698D7C0B45DDD3C5531C9B7A552" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2019 (remaining nine months)</link:label>
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    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_95B4DF8FEA11012FBAC95531C9B8C7AB_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_95B4DF8FEA11012FBAC95531C9B8C7AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2020</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_95B4DF8FEA11012FBAC95531C9B8C7AB" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearTwo_95B4DF8FEA11012FBAC95531C9B8C7AB" xlink:type="arc" />
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2021</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due Year Three</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearThree_A505A5C53FA28D215AF85531C9B86DB1" xlink:type="arc" />
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_3C918B135767F377E72E5531C9B80785_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_3C918B135767F377E72E5531C9B80785" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2022</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_3C918B135767F377E72E5531C9B80785_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_3C918B135767F377E72E5531C9B80785" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due Year Four</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFour_3C918B135767F377E72E5531C9B80785" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2023</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due Year Five</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491" xlink:to="lab_us-gaap_FinanceLeaseLiabilityPaymentsDueYearFive_8A3CB0FCF657000D6F1B5531C9B85491" xlink:type="arc" />
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC_terseLabel_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">2024</link:label>
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC_label_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due Year Six</link:label>
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC_documentation_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due Year Six</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_FinanceLeaseLiabilityPaymentsDueYearSix" xlink:label="loc_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:to="lab_clh_FinanceLeaseLiabilityPaymentsDueYearSix_9E66797F071C55CDE8255531C9B97BBC" xlink:type="arc" />
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0_terseLabel_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Thereafter</link:label>
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0_label_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due after Year Six</link:label>
    <link:label id="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0_documentation_en-US" xlink:label="lab_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due after Year Six</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_FinanceLeaseLiabilityPaymentsDueafterYearSix" xlink:label="loc_clh_FinanceLeaseLiabilityPaymentsDueafterYearSix_C8606EDDEFBC4511E3295531C9B956C0" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_04EA442FE2FC89E4E1C15531C9B9E89E_totalLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_04EA442FE2FC89E4E1C15531C9B9E89E" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total future lease payments</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_04EA442FE2FC89E4E1C15531C9B9E89E_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiabilityPaymentsDue_04EA442FE2FC89E4E1C15531C9B9E89E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Liability, Payments, Due</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityPaymentsDue" xlink:label="loc_us-gaap_FinanceLeaseLiabilityPaymentsDue_04EA442FE2FC89E4E1C15531C9B9E89E" xlink:type="locator" />
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount" xlink:label="loc_us-gaap_FinanceLeaseLiabilityUndiscountedExcessAmount_830BD89F316CAB1429B85531C9B94199" xlink:type="locator" />
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    <link:label id="lab_us-gaap_FinanceLeaseLiability_A02F7C143AD147781C705531C9B9B50C_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseLiability_A02F7C143AD147781C705531C9B9B50C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Total lease liabilities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseLiability" xlink:label="loc_us-gaap_FinanceLeaseLiability_A02F7C143AD147781C705531C9B9B50C" xlink:type="locator" />
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    <link:label id="lab_srt_ConsolidationEliminationsMember_BC482195FB2869AB6C396E9F2E81B009_terseLabel_en-US" xlink:label="lab_srt_ConsolidationEliminationsMember_BC482195FB2869AB6C396E9F2E81B009" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Consolidating Adjustments</link:label>
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    <link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_6E9F2D0465498149A2DC6E9F2E813714_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_6E9F2D0465498149A2DC6E9F2E813714" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Net cash from operating activities</link:label>
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    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsToAcquireIntangibleAssets" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_0B2DBE0DF1B24F7EC3E06E9F3233EABF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireIntangibleAssets_0B2DBE0DF1B24F7EC3E06E9F3233EABF" xlink:to="lab_us-gaap_PaymentsToAcquireIntangibleAssets_0B2DBE0DF1B24F7EC3E06E9F3233EABF" xlink:type="arc" />
    <link:label id="lab_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Proceeds from sale of available-for-sale securities</link:label>
    <link:label id="lab_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432_label_en-US" xlink:label="lab_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Proceeds from Sale of Debt Securities, Available-for-sale</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt" xlink:label="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432" xlink:to="lab_us-gaap_ProceedsFromSaleOfAvailableForSaleSecuritiesDebt_44DCCE4074C12846573F6E9F3233F432" xlink:type="arc" />
    <link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_94A0FCEE0BEB3A2467F36E9F3234A8C6_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_94A0FCEE0BEB3A2467F36E9F3234A8C6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash flows used in financing activities:</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_94A0FCEE0BEB3A2467F36E9F3234A8C6" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_94A0FCEE0BEB3A2467F36E9F3234A8C6" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_94A0FCEE0BEB3A2467F36E9F3234A8C6" xlink:type="arc" />
    <link:label id="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_9AA42E1770ABD0AAED7E6E9F323535E8_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_9AA42E1770ABD0AAED7E6E9F323535E8" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Tax payments related to withholdings on vested restricted stock</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation" xlink:label="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_9AA42E1770ABD0AAED7E6E9F323535E8" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_9AA42E1770ABD0AAED7E6E9F323535E8" xlink:to="lab_us-gaap_PaymentsRelatedToTaxWithholdingForShareBasedCompensation_9AA42E1770ABD0AAED7E6E9F323535E8" xlink:type="arc" />
    <link:label id="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41_negatedTerseLabel_en-US" xlink:label="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Payments on finance lease</link:label>
    <link:label id="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41_label_en-US" xlink:label="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payments on Financing Leases</link:label>
    <link:label id="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41_documentation_en-US" xlink:label="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Payments on Financing Leases</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_PaymentsonFinancingLeases" xlink:label="loc_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:to="lab_clh_PaymentsonFinancingLeases_09C355EEC2FA4A37395F6E9F3235EF41" xlink:type="arc" />
    <link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F_terseLabel_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Supplemental information:</link:label>
    <link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F_label_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Supplemental Cash Flow Information [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F" xlink:to="lab_us-gaap_SupplementalCashFlowInformationAbstract_F11C3628DC99440C3FE66E9F323B967F" xlink:type="arc" />
    <link:label id="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43_terseLabel_en-US" xlink:label="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash payments for interest and income taxes:</link:label>
    <link:label id="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43_label_en-US" xlink:label="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cash Payments for Interest and Income Taxes [Abstract]</link:label>
    <link:label id="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43_documentation_en-US" xlink:label="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Description and amounts of long lived assets and liabilities held for sale. Disclosure may include the description of the facts and circumstances leading to the expected disposal, manner and timing of disposal, the carrying value of the assets and liabilities held for sale, the gain or loss recognized in the income statement and the income statement caption that includes that gain or loss.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_CashPaymentsForInterestAndIncomeTaxesAbstract" xlink:label="loc_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:to="lab_clh_CashPaymentsForInterestAndIncomeTaxesAbstract_84DF1D01D85D7DC571566E9F323CED43" xlink:type="arc" />
    <link:label id="lab_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA_terseLabel_en-US" xlink:label="lab_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Interest paid</link:label>
    <link:label id="lab_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA_label_en-US" xlink:label="lab_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Interest Paid, Excluding Capitalized Interest, Operating Activities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InterestPaidNet" xlink:label="loc_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA" xlink:to="lab_us-gaap_InterestPaidNet_EDEB2E67DBA2E90D2B686E9F323C65EA" xlink:type="arc" />
    <link:label id="lab_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Income taxes paid</link:label>
    <link:label id="lab_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE_label_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Income Taxes Paid, Net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE" xlink:to="lab_us-gaap_IncomeTaxesPaidNet_F4271DB9B3246AC26F726E9F323C4BBE" xlink:type="arc" />
    <link:label id="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962_terseLabel_en-US" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Non-cash investing activities:</link:label>
    <link:label id="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962_label_en-US" xlink:label="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962" xlink:to="lab_us-gaap_CashFlowNoncashInvestingAndFinancingActivitiesDisclosureAbstract_D0F5B67C8AA966A2FBFE6E9F323D3962" xlink:type="arc" />
    <link:label id="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B_terseLabel_en-US" xlink:label="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Property, plant and equipment accrued</link:label>
    <link:label id="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B_label_en-US" xlink:label="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Noncash or Part Noncash Acquisition, Value of Assets Acquired</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1" xlink:label="loc_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B" xlink:to="lab_us-gaap_NoncashOrPartNoncashAcquisitionValueOfAssetsAcquired1_C8C5FFF91138784E5C306E9F323DA54B" xlink:type="arc" />
    <link:label id="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4_terseLabel_en-US" xlink:label="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash paid for amounts included in the measurement of lease liabilities:</link:label>
    <link:label id="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4_label_en-US" xlink:label="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Cash Flow, Lessee [Abstract]</link:label>
    <link:label id="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4_documentation_en-US" xlink:label="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Cash Flow, Lessee [Abstract]</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_CashFlowLesseeAbstract" xlink:label="loc_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:to="lab_clh_CashFlowLesseeAbstract_CD1E2198DEBA495EE52A6E9F323DE3D4" xlink:type="arc" />
    <link:label id="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5_terseLabel_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating cash flows from finance lease</link:label>
    <link:label id="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5_label_en-US" xlink:label="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Finance Lease, Interest Payment on Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_FinanceLeaseInterestPaymentOnLiability" xlink:label="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5" xlink:to="lab_us-gaap_FinanceLeaseInterestPaymentOnLiability_A3BF49794CD1258D11846E9F323EA5B5" xlink:type="arc" />
    <link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D_terseLabel_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">ROU assets obtained in exchange for new operating lease liabilities</link:label>
    <link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D_label_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Right-of-Use Asset Obtained in Exchange for Operating Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D" xlink:to="lab_us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability_C0A10B8CA58111FB23046E9F323E054D" xlink:type="arc" />
    <link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89_terseLabel_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">ROU asset obtained in exchange for new finance lease liability</link:label>
    <link:label id="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89_label_en-US" xlink:label="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Right-of-Use Asset Obtained in Exchange for Finance Lease Liability</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability" xlink:label="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89" xlink:to="lab_us-gaap_RightOfUseAssetObtainedInExchangeForFinanceLeaseLiability_D695135F5C118F07AE086E9F323EAF89" xlink:type="arc" />
    <link:label id="lab_srt_CondensedFinancialStatementsCaptionsLineItems_731BFB9C36B23BB0646165DB08B1E462_terseLabel_en-US" xlink:label="lab_srt_CondensedFinancialStatementsCaptionsLineItems_731BFB9C36B23BB0646165DB08B1E462" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Condensed consolidating balance sheet</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2018/elts/srt-2018-01-31.xsd#srt_CondensedFinancialStatementsCaptionsLineItems" xlink:label="loc_srt_CondensedFinancialStatementsCaptionsLineItems_731BFB9C36B23BB0646165DB08B1E462" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_srt_CondensedFinancialStatementsCaptionsLineItems_731BFB9C36B23BB0646165DB08B1E462" xlink:to="lab_srt_CondensedFinancialStatementsCaptionsLineItems_731BFB9C36B23BB0646165DB08B1E462" xlink:type="arc" />
    <link:label id="lab_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">ASSETS</link:label>
    <link:label id="lab_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C_label_en-US" xlink:label="lab_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Assets [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AssetsAbstract" xlink:label="loc_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C" xlink:to="lab_us-gaap_AssetsAbstract_B3789BEA80C9B1564D9C65DB08B12A9C" xlink:type="arc" />
    <link:label id="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC0DCDEAF67C6D6314DD65DB08B21088_terseLabel_en-US" xlink:label="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC0DCDEAF67C6D6314DD65DB08B21088" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Cash and cash equivalents</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents" xlink:label="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC0DCDEAF67C6D6314DD65DB08B21088" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC0DCDEAF67C6D6314DD65DB08B21088" xlink:to="lab_us-gaap_CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents_AC0DCDEAF67C6D6314DD65DB08B21088" xlink:type="arc" />
    <link:label id="lab_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51_verboseLabel_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Short-term marketable securities</link:label>
    <link:label id="lab_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51_label_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Marketable Securities, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_MarketableSecuritiesCurrent" xlink:label="loc_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51" xlink:to="lab_us-gaap_MarketableSecuritiesCurrent_8AC0C7EFA3DAE52CEDA865DB08B2EC51" xlink:type="arc" />
    <link:label id="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE_terseLabel_en-US" xlink:label="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intercompany receivables</link:label>
    <link:label id="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE_label_en-US" xlink:label="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Receivables from Affiliates Subsidiaries and Holding Companies</link:label>
    <link:label id="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE_documentation_en-US" xlink:label="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents receivables from affiliates, subsidiaries and the holding company.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies" xlink:label="loc_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:to="lab_clh_ReceivablesFromAffiliatesSubsidiariesAndHoldingCompanies_992FF233223B640A125B65DB08B741BE" xlink:type="arc" />
    <link:label id="lab_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Accounts receivable, net</link:label>
    <link:label id="lab_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Accounts Receivable, Net, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281" xlink:to="lab_us-gaap_AccountsReceivableNetCurrent_4E853E392320FE36649865DB08B72281" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other current assets</link:label>
    <link:label id="lab_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125_label_en-US" xlink:label="lab_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Assets, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsCurrent" xlink:label="loc_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125" xlink:to="lab_us-gaap_OtherAssetsCurrent_074A9F48907481BB920665DB08B8D125" xlink:type="arc" />
    <link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_07F2885A7ECDC663F12D65DB08B81DDE_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_07F2885A7ECDC663F12D65DB08B81DDE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Property, plant and equipment, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_07F2885A7ECDC663F12D65DB08B81DDE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_07F2885A7ECDC663F12D65DB08B81DDE" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentNet_07F2885A7ECDC663F12D65DB08B81DDE" xlink:type="arc" />
    <link:label id="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Investments in subsidiaries</link:label>
    <link:label id="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E_label_en-US" xlink:label="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures" xlink:label="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E" xlink:to="lab_us-gaap_InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures_D968D85F62DA1580612365DB08B8982E" xlink:type="arc" />
    <link:label id="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4_terseLabel_en-US" xlink:label="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intercompany debt receivable</link:label>
    <link:label id="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4_label_en-US" xlink:label="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Receivable from Affiliates Subsidiaries and Holding Companies</link:label>
    <link:label id="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4_documentation_en-US" xlink:label="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents debts receivable from the affiliates, subsidiaries and the holding company.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies" xlink:label="loc_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:to="lab_clh_DebtReceivableFromAffiliatesSubsidiariesAndHoldingCompanies_E1C316D3A5BC3A674BB265DB08B806B4" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other long-term assets</link:label>
    <link:label id="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0_label_en-US" xlink:label="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Assets, Miscellaneous, Noncurrent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherAssetsMiscellaneousNoncurrent" xlink:label="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0" xlink:to="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_0FDF3BF1027C900E74FC65DB08B91BF0" xlink:type="arc" />
    <link:label id="lab_us-gaap_Assets_DBB47785BC6E3DE974FC65DB08B917D3_totalLabel_en-US" xlink:label="lab_us-gaap_Assets_DBB47785BC6E3DE974FC65DB08B917D3" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total assets</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_DBB47785BC6E3DE974FC65DB08B917D3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Assets_DBB47785BC6E3DE974FC65DB08B917D3" xlink:to="lab_us-gaap_Assets_DBB47785BC6E3DE974FC65DB08B917D3" xlink:type="arc" />
    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">LIABILITIES AND STOCKHOLDERS' EQUITY</link:label>
    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities and Equity [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_51A4733CBCA8B86E85B465DB08B9DFF3" xlink:type="arc" />
    <link:label id="lab_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Current liabilities</link:label>
    <link:label id="lab_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities, Current</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesCurrent" xlink:label="loc_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752" xlink:to="lab_us-gaap_LiabilitiesCurrent_B884DC205548CA1EE51A65DB08B9E752" xlink:type="arc" />
    <link:label id="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF_terseLabel_en-US" xlink:label="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intercompany payables</link:label>
    <link:label id="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF_label_en-US" xlink:label="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Payables to Affiliates Subsidiaries and Holding Companies</link:label>
    <link:label id="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF_documentation_en-US" xlink:label="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents payables to affiliates, subsidiaries and the holding company.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies" xlink:label="loc_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:to="lab_clh_PayablesToAffiliatesSubsidiariesAndHoldingCompanies_78FCBAC0D57169972FE265DB08BAE7AF" xlink:type="arc" />
    <link:label id="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F_terseLabel_en-US" xlink:label="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Closure, post-closure and remedial liabilities, net</link:label>
    <link:label id="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F_label_en-US" xlink:label="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Closure Post Closure and Remedial Liabilities, Net</link:label>
    <link:label id="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F_documentation_en-US" xlink:label="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The net amount of closure, post-closure and remedial liabilities that is required as of the balance sheet date, which will be paid after one year or beyond the normal operating cycle, if longer.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_ClosurePostClosureAndRemedialLiabilitiesNet" xlink:label="loc_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:to="lab_clh_ClosurePostClosureAndRemedialLiabilitiesNet_A525E309A8170FDC982265DB08BADB8F" xlink:type="arc" />
    <link:label id="lab_us-gaap_LongTermDebtNoncurrent_40646180F6EF0568301D65DB08BA0A62_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtNoncurrent_40646180F6EF0568301D65DB08BA0A62" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Long-term obligations, less current portion</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LongTermDebtNoncurrent" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_40646180F6EF0568301D65DB08BA0A62" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongTermDebtNoncurrent_40646180F6EF0568301D65DB08BA0A62" xlink:to="lab_us-gaap_LongTermDebtNoncurrent_40646180F6EF0568301D65DB08BA0A62" xlink:type="arc" />
    <link:label id="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360_terseLabel_en-US" xlink:label="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Operating lease liabilities, less current portion</link:label>
    <link:label id="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360_label_en-US" xlink:label="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Operating and Finance Lease, Liability, Noncurrent</link:label>
    <link:label id="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360_documentation_en-US" xlink:label="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Operating and Finance Lease, Liability, Noncurrent</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_OperatingandFinanceLeaseLiabilityNoncurrent" xlink:label="loc_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:to="lab_clh_OperatingandFinanceLeaseLiabilityNoncurrent_74C64B6CA8F4941EDA7865DB08BAF360" xlink:type="arc" />
    <link:label id="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5_terseLabel_en-US" xlink:label="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Intercompany debt payable</link:label>
    <link:label id="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5_label_en-US" xlink:label="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Payable to Affiliates Subsidiaries and Holding Companies</link:label>
    <link:label id="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5_documentation_en-US" xlink:label="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the debts payable to the affiliates, subsidiaries and the holding company.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies" xlink:label="loc_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:to="lab_clh_DebtPayableToAffiliatesSubsidiariesAndHoldingCompanies_CE666AB4E098513D65C865DB08BA1ED5" xlink:type="arc" />
    <link:label id="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A_verboseLabel_en-US" xlink:label="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Other long-term liabilities</link:label>
    <link:label id="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A_label_en-US" xlink:label="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Unrecognized Tax Benefits and Other Long-term Liabilities, Noncurrent</link:label>
    <link:label id="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A_documentation_en-US" xlink:label="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The noncurrent portion of the amount that is recognized for the unrecognized tax benefits and other long-term liabilities as of the balance sheet date.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent" xlink:label="loc_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:to="lab_clh_UnrecognizedTaxBenefitsAndOtherLongTermLiabilitiesNoncurrent_66A77387D3FD1C4DA75C65DB08BB0E2A" xlink:type="arc" />
    <link:label id="lab_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA_totalLabel_en-US" xlink:label="lab_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total liabilities</link:label>
    <link:label id="lab_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA_label_en-US" xlink:label="lab_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_Liabilities" xlink:label="loc_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA" xlink:to="lab_us-gaap_Liabilities_C9D76E789E3B0801AC6D65DB08BB85EA" xlink:type="arc" />
    <link:label id="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C9B15D46CE07E2890C5465DB08BB4AA1_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C9B15D46CE07E2890C5465DB08BB4AA1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Stockholders&#8217; equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C9B15D46CE07E2890C5465DB08BB4AA1" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C9B15D46CE07E2890C5465DB08BB4AA1" xlink:to="lab_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_C9B15D46CE07E2890C5465DB08BB4AA1" xlink:type="arc" />
    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Total liabilities and stockholders&#8217; equity</link:label>
    <link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Liabilities and Equity</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquity" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64" xlink:to="lab_us-gaap_LiabilitiesAndStockholdersEquity_557F846C77F0CBD5F23665DB08BB3B64" xlink:type="arc" />
    <link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_A3FB079D96929F3892DB3D55BEF148AC_terseLabel_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock_5B1C341851B25A1F8F5CFEB9A72350AE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">SIGNIFICANT ACCOUNTING POLICIES</link:label>
    <link:label id="lab_us-gaap_SignificantAccountingPoliciesTextBlock_A3FB079D96929F3892DB3D55BEF148AC_label_en-US" xlink:label="lab_us-gaap_SignificantAccountingPoliciesTextBlock_5B1C341851B25A1F8F5CFEB9A72350AE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Significant Accounting Policies [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SignificantAccountingPoliciesTextBlock" xlink:label="loc_us-gaap_SignificantAccountingPoliciesTextBlock_5B1C341851B25A1F8F5CFEB9A72350AE" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SignificantAccountingPoliciesTextBlock_5B1C341851B25A1F8F5CFEB9A72350AE" xlink:to="lab_us-gaap_SignificantAccountingPoliciesTextBlock_5B1C341851B25A1F8F5CFEB9A72350AE" xlink:type="arc" />
    <link:label id="lab_us-gaap_DebtDisclosureTextBlock_2B26F1612B5E595FCFCB9B0CB57D0DC5_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock_96BF8C3499335CB488F78DBBD241155D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">FINANCING ARRANGEMENTS</link:label>
    <link:label id="lab_us-gaap_DebtDisclosureTextBlock_2B26F1612B5E595FCFCB9B0CB57D0DC5_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock_96BF8C3499335CB488F78DBBD241155D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Debt Disclosure [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DebtDisclosureTextBlock" xlink:label="loc_us-gaap_DebtDisclosureTextBlock_96BF8C3499335CB488F78DBBD241155D" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureTextBlock_96BF8C3499335CB488F78DBBD241155D" xlink:to="lab_us-gaap_DebtDisclosureTextBlock_96BF8C3499335CB488F78DBBD241155D" xlink:type="arc" />
    <link:label id="lab_us-gaap_ComprehensiveIncomeNoteTextBlock_48CCF11A799FB14C365F3D55BFD41A85_terseLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNoteTextBlock_E2D9CC5CC31655E5A571D609ADBF06B3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">ACCUMULATED OTHER COMPREHENSIVE LOSS</link:label>
    <link:label id="lab_us-gaap_ComprehensiveIncomeNoteTextBlock_48CCF11A799FB14C365F3D55BFD41A85_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomeNoteTextBlock_E2D9CC5CC31655E5A571D609ADBF06B3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Comprehensive Income (Loss) Note [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_ComprehensiveIncomeNoteTextBlock" xlink:label="loc_us-gaap_ComprehensiveIncomeNoteTextBlock_E2D9CC5CC31655E5A571D609ADBF06B3" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComprehensiveIncomeNoteTextBlock_E2D9CC5CC31655E5A571D609ADBF06B3" xlink:to="lab_us-gaap_ComprehensiveIncomeNoteTextBlock_E2D9CC5CC31655E5A571D609ADBF06B3" xlink:type="arc" />
    <link:label id="lab_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783_terseLabel_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Disaggregation of Revenue [Table]</link:label>
    <link:label id="lab_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783_label_en-US" xlink:label="lab_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Disaggregation of Revenue [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_DisaggregationOfRevenueTable" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783" xlink:to="lab_us-gaap_DisaggregationOfRevenueTable_F2553D4EDD3F338AE0675531CBA93783" xlink:type="arc" />
    <link:label id="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440_terseLabel_en-US" xlink:label="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Technical Services</link:label>
    <link:label id="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440_label_en-US" xlink:label="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Technical Services [Member]</link:label>
    <link:label id="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440_documentation_en-US" xlink:label="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the Technical Services segment of the entity.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_TechnicalServicesMember" xlink:label="loc_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:to="lab_clh_TechnicalServicesMember_961097854BB22DE8E1D05531CBB30440" xlink:type="arc" />
    <link:label id="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F_terseLabel_en-US" xlink:label="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Field and Emergency Response Services</link:label>
    <link:label id="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F_label_en-US" xlink:label="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Field and Emergency Response [Member]</link:label>
    <link:label id="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F_documentation_en-US" xlink:label="lab_clh_FieldandEmergencyResponseMember_D7324D9D3D97ABFE69EB5531CBB3BE4F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Field and Emergency Response [Member]</link:label>
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    <link:label id="lab_clh_OilGasandLodgingServicesMember_D84BEC34D678841D49E35531CBB36B2B_terseLabel_en-US" xlink:label="lab_clh_OilGasandLodgingServicesMember_D84BEC34D678841D49E35531CBB36B2B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Oil, Gas and Lodging Services and Other</link:label>
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    <link:label id="lab_us-gaap_MarketableSecuritiesCurrent_3AD93E15F76E72C6D2AD65DB6B7A1F8D_terseLabel_en-US" xlink:label="lab_us-gaap_MarketableSecuritiesCurrent_3AD93E15F76E72C6D2AD65DB6B7A1F8D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Short-term marketable securities</link:label>
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    <link:label id="lab_clh_UnbilledAccountsReceivableCurrent_E089440F6D88EA56AFB665DB6B7BC38B_documentation_en-US" xlink:label="lab_clh_UnbilledAccountsReceivableCurrent_E089440F6D88EA56AFB665DB6B7BC38B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">The aggregate amount of unbilled receivables due for services rendered or to be rendered at the financial statement date, which are usually due within one year (or one business cycle).</link:label>
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    <link:label id="lab_clh_AccruedCappingClosurePostClosureAndRemedialLiabilitiesCurrent_CCD1CACB0CDE3847889765DB6B7E9F98_terseLabel_en-US" xlink:label="lab_clh_AccruedCappingClosurePostClosureAndRemedialLiabilitiesCurrent_CCD1CACB0CDE3847889765DB6B7E9F98" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Current portion of closure, post-closure and remedial liabilities</link:label>
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    <link:label id="lab_us-gaap_OperatingLeaseLiabilityCurrent_E45017F41379C187EA5365DB6B7F9B24_verboseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeaseLiabilityCurrent_E45017F41379C187EA5365DB6B7F9B24" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Current portion of operating lease liability</link:label>
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    <link:label id="lab_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E_terseLabel_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Other liabilities:</link:label>
    <link:label id="lab_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E_label_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Liabilities, Noncurrent [Abstract]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrentAbstract" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E" xlink:to="lab_us-gaap_OtherLiabilitiesNoncurrentAbstract_7C7C7A5CB28BCA654F6465DB6B7FD09E" xlink:type="arc" />
    <link:label id="lab_us-gaap_AccruedCappingClosurePostClosureAndEnvironmentalCostsNoncurrent_2002086990294CEA449665DB6B7FD9B0_verboseLabel_en-US" xlink:label="lab_us-gaap_AccruedCappingClosurePostClosureAndEnvironmentalCostsNoncurrent_2002086990294CEA449665DB6B7FD9B0" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US">Closure and post-closure liabilities, less current portion of $12,337 and $9,592, respectively</link:label>
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    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_56E05ACEA5F213D7CCCB5531CC216005" xlink:to="lab_us-gaap_OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax_56E05ACEA5F213D7CCCB5531CC216005" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Unrealized loss on interest rate hedge</link:label>
    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180" xlink:type="locator" />
    <link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax_5FE8C04DF8649C0E80755531CC213180" xlink:type="arc" />
    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_BC93B98267FC84DEC4565531CC21F498_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_BC93B98267FC84DEC4565531CC21F498" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Reclassification adjustment for losses on interest rate hedge included in net income (loss) (net of taxes of $0 and $0, respectively)</link:label>
    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_BC93B98267FC84DEC4565531CC21F498_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_BC93B98267FC84DEC4565531CC21F498" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationAfterTax_BC93B98267FC84DEC4565531CC21F498" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_87228C5EF076C60E213C5531CC218969_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_87228C5EF076C60E213C5531CC218969" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Foreign currency translation adjustments</link:label>
    <link:label id="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_87228C5EF076C60E213C5531CC218969_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_87228C5EF076C60E213C5531CC218969" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_87228C5EF076C60E213C5531CC218969" xlink:type="locator" />
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    <link:label id="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_9CAE965BBA3C168C0A0F5531CC21057B_totalLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_9CAE965BBA3C168C0A0F5531CC21057B" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US">Other comprehensive income (loss)</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_9CAE965BBA3C168C0A0F5531CC21057B" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EnvironmentalLossContingencyDisclosureTextBlock_B12B1F3BF26B0126B12F2234A3588C88_terseLabel_en-US" xlink:label="lab_us-gaap_EnvironmentalLossContingencyDisclosureTextBlock_B12B1F3BF26B0126B12F2234A3588C88" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">REMEDIAL LIABILITIES</link:label>
    <link:label id="lab_us-gaap_EnvironmentalLossContingencyDisclosureTextBlock_B12B1F3BF26B0126B12F2234A3588C88_label_en-US" xlink:label="lab_us-gaap_EnvironmentalLossContingencyDisclosureTextBlock_B12B1F3BF26B0126B12F2234A3588C88" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Environmental Loss Contingency Disclosure [Text Block]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EnvironmentalLossContingencyDisclosureTextBlock" xlink:label="loc_us-gaap_EnvironmentalLossContingencyDisclosureTextBlock_B12B1F3BF26B0126B12F2234A3588C88" xlink:type="locator" />
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    <link:label id="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC_terseLabel_en-US" xlink:label="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Adjusted EBITDA</link:label>
    <link:label id="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC_label_en-US" xlink:label="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Income (Loss) from Continuing Operations before Interest, Tax, Depreciation and Amortization, Net</link:label>
    <link:label id="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC_documentation_en-US" xlink:label="lab_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the income or loss from continuing operations before interest, taxes, depreciation and amortization to the economic entity.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet" xlink:label="loc_clh_IncomeLossFromContinuingOperationsBeforeInterestTaxDepreciationAndAmortizationNet_B474C91E908BF1A315F54209DB52B4DC" xlink:type="locator" />
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    <link:label id="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6_terseLabel_en-US" xlink:label="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Reconciliation to Consolidated Statements of Operations:</link:label>
    <link:label id="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6_label_en-US" xlink:label="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Reconciliation Between Adjusted EBITDA and Income Statement [Abstract]</link:label>
    <link:label id="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6_documentation_en-US" xlink:label="lab_clh_ReconciliationBetweenAdjustedEBITDAandIncomeStatementAbstract_6CD35EBBDD9C1A3DD39A4209DB53D2F6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">Reconciliation Between Adjusted EBITDA and Income Statement [Abstract]</link:label>
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    <link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_1FB2BF2F34C85CFE83084209DB5438AB_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense_1FB2BF2F34C85CFE83084209DB5438AB" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Other (income) expense, net</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_OtherNonoperatingIncomeExpense" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_1FB2BF2F34C85CFE83084209DB5438AB" xlink:type="locator" />
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    <link:label id="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_DC26301039E67C43F4A84209DB5420DC_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_InterestIncomeExpenseNonoperatingNet_DC26301039E67C43F4A84209DB5420DC" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US">Interest expense, net of interest income</link:label>
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    <link:label id="lab_us-gaap_SiteContingencyTable_3615C255B7E9732314892234A345F4F4_terseLabel_en-US" xlink:label="lab_us-gaap_SiteContingencyTable_3615C255B7E9732314892234A345F4F4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Site Contingency [Table]</link:label>
    <link:label id="lab_us-gaap_SiteContingencyTable_3615C255B7E9732314892234A345F4F4_label_en-US" xlink:label="lab_us-gaap_SiteContingencyTable_3615C255B7E9732314892234A345F4F4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Site Contingency [Table]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_SiteContingencyTable" xlink:label="loc_us-gaap_SiteContingencyTable_3615C255B7E9732314892234A345F4F4" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EnvironmentalRemediationSiteAxis_683D67D72E1B05D75BD72234A345EFD5_terseLabel_en-US" xlink:label="lab_us-gaap_EnvironmentalRemediationSiteAxis_683D67D72E1B05D75BD72234A345EFD5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Environmental Remediation Site [Axis]</link:label>
    <link:label id="lab_us-gaap_EnvironmentalRemediationSiteAxis_683D67D72E1B05D75BD72234A345EFD5_label_en-US" xlink:label="lab_us-gaap_EnvironmentalRemediationSiteAxis_683D67D72E1B05D75BD72234A345EFD5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Environmental Remediation Site [Axis]</link:label>
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2018/elts/us-gaap-2018-01-31.xsd#us-gaap_EnvironmentalRemediationSiteAxis" xlink:label="loc_us-gaap_EnvironmentalRemediationSiteAxis_683D67D72E1B05D75BD72234A345EFD5" xlink:type="locator" />
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    <link:label id="lab_us-gaap_EnvironmentalRemediationSiteDomain_497DF2957E4D7FD74B532234A345CDB5_terseLabel_en-US" xlink:label="lab_us-gaap_EnvironmentalRemediationSiteDomain_497DF2957E4D7FD74B532234A345CDB5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Environmental Remediation Site [Domain]</link:label>
    <link:label id="lab_us-gaap_EnvironmentalRemediationSiteDomain_497DF2957E4D7FD74B532234A345CDB5_label_en-US" xlink:label="lab_us-gaap_EnvironmentalRemediationSiteDomain_497DF2957E4D7FD74B532234A345CDB5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US">Environmental Remediation Site [Domain]</link:label>
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    <link:label id="lab_clh_RemedialLiabilitiesForLandfillSitesMember_074EF089D7B6C71601272234A3462580_terseLabel_en-US" xlink:label="lab_clh_RemedialLiabilitiesForLandfillSitesMember_074EF089D7B6C71601272234A3462580" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US">Remedial Liabilities for Landfill Sites</link:label>
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    <link:label id="lab_clh_RemedialLiabilitiesForLandfillSitesMember_074EF089D7B6C71601272234A3462580_documentation_en-US" xlink:label="lab_clh_RemedialLiabilitiesForLandfillSitesMember_074EF089D7B6C71601272234A3462580" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US">This element represents the details that pertain to the remedial liability for landfill sites.</link:label>
    <link:loc xlink:href="clh-20190331.xsd#clh_RemedialLiabilitiesForLandfillSitesMember" xlink:label="loc_clh_RemedialLiabilitiesForLandfillSitesMember_074EF089D7B6C71601272234A3462580" xlink:type="locator" />
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