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SEC EDGAR · Amended filing

CLH: amended insider filing

An amended ownership report was filed. Read the original and amendment before comparing transactions.

Follow CLH
Became public
May 14, 2026, 10:12 AM EDT
Event / period date
May 11, 2026
Collected
Nov 10, 2026, 6:17 PM EST

Why this is connected

This filing identifies CLEAN HARBORS INC as the issuer of the security. The company's SEC identifier connects it to CLH.

Open the original source ↗Follow company activity in CLH

Reported transactions

Polito Karyn (Director)

460 shares · Common Stock

May 11, 2026 · $295.13 per share

Value calculated from the reported shares and prices: $135,759.80.

Code P covers open-market and private purchases. Grants, option exercises, and tax withholding are excluded from purchase results. Read the source footnotes for ownership and pricing details.

Source evidence

Read the source excerpt or record
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0609</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2026-05-11</periodOfReport>

    <dateOfOriginalSubmission>2026-05-13</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0000822818</issuerCik>
        <issuerName>CLEAN HARBORS INC</issuerName>
        <issuerTradingSymbol>CLH</issuerTradingSymbol>
        <issuerForeignTradingSymbol></issuerForeignTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001965457</rptOwnerCik>
            <rptOwnerName>Polito Karyn</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerNonUSAddressFlag>false</rptOwnerNonUSAddressFlag>
            <rptOwnerStreet1>C/O CLEAN HARBORS, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>42 LONGWATER DRIVE</rptOwnerStreet2>
            <rptOwnerCity>NORWELL</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02061</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <aff10b5One>0</aff10b5One>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2026-05-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>460</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>295.13</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3475</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Item 3, Transaction Code, edited to correct a clerical error.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Karyn Polito</signatureName>
        <signatureDate>2026-05-14</signatureDate>
    </ownerSignature>
</ownershipDocument>

Congressional trading in CLH

These disclosures provide context. Their presence does not establish a link between a trader and the event.

Original documents control. Public records can be amended, and company connections may require interpretation. Nothing here is investment advice.