Form 8-K

8-K — CLEAN HARBORS INC

Accession: 0000822818-26-000040

Filed: 2026-09-18

Period: 2026-09-17

CIK: 0000822818

SIC: 4955 (HAZARDOUS WASTE MANAGEMENT)

Item: Other Events

Item: Financial Statements and Exhibits

Documents

8-K — clh-20260917.htm (Primary)

EX-99.1 (clh-notesofferinglaunchrel.htm)

EX-99.2 (clh-notesofferingpricingre.htm)

GRAPHIC (image.jpg)

GRAPHIC (imageb.jpg)

XML — IDEA: XBRL DOCUMENT (R1.htm)

8-K

8-K (Primary)

Filename: clh-20260917.htm · Sequence: 1

clh-20260917

0000822818false00008228182026-09-172026-09-17

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): September 17, 2026

CLEAN HARBORS, INC.

(Exact name of registrant as specified in its charter)

Massachusetts

001-34223

04-2997780

(State or other jurisdiction

of incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

42 Longwater Drive Norwell MA 02061-9149

(Address of Principal Executive Offices) (Zip Code)

Registrant’s telephone number, including area code (781) 792-5000

Not Applicable

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Securities registered pursuant to Section 12(b) of the Act:

Title of each class Trading Symbol

Name of each exchange on which registered

Common Stock, $0.01 par value

CLH

New York Stock Exchange

Item 8.01. Other Events.

On September 17, 2026, Clean Harbors, Inc. (the “Company”) issued a press release announcing that it had commenced a private offering of senior notes due 2034 to persons reasonably believed to be “qualified institutional buyers” in the United States, as defined in Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”), and to certain non-U.S. persons outside the United States in offshore transactions pursuant to Regulation S under the Securities Act.

On September 17, 2026, the Company issued a press release announcing the pricing of its previously announced offering of 6.250% senior notes due 2034 (the “Notes”).

Copies of the press releases are attached as Exhibit 99.1 and 99.2 to this Current Report on Form 8-K and are incorporated by reference into this Item 8.01.

Neither this Current Report on Form 8-K nor the press releases constitute an offer to sell, or the solicitation of an offer to buy, the Notes.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number Description

99.1

Press release of the Company relating to the announcement of the offering, dated September 17, 2026

99.2

Press release of the Company relating to the pricing of the offering, dated September 17, 2026

104 Cover Page Interactive Data File (embedded within the Inline XBRL document)

SIGNATURES

Pursuant to the requirements of the Securities and Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Clean Harbors, Inc.

(Registrant)

September 18, 2026 /s/ Eric J. Dugas

Executive Vice President and Chief Financial Officer

EX-99.1

Filename: clh-notesofferinglaunchrel.htm · Sequence: 2

Document

EXHIBIT 99.1

Press Release

Clean Harbors Announces $600 Million Senior Notes Offering

NORWELL, Mass. – September 17, 2026 – Clean Harbors, Inc. (“Clean Harbors” or the “Company”) (NYSE: CLH), announced today that it is commencing a private offering of $600 million of senior notes (the “notes”). Clean Harbors expects the notes to mature in 2034.

The Company intends to use the net proceeds from the offering of notes to finance the purchase price of the Company’s previously announced acquisition of EnviroServe, a national provider of environmental and waste management services (the “EnviroServe Acquisition”), and the remainder of the net proceeds to repay the borrowings under its revolving credit facility that were incurred to partially finance the purchase price of the Company’s previously announced acquisition of ES&H (the “ES&H Acquisition” and, together with the EnviroServe Acquisition, the “Acquisitions”). There can be no assurance that the Acquisitions will be completed on the terms the Company anticipates, in a timely manner or at all. The consummation of the offering of notes is not contingent on the completion of the Acquisitions and, if either Acquisition is not completed, the Company intends to use the remaining net proceeds for general corporate purposes.

The notes will be offered and sold to persons reasonably believed to be qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, as amended (the “Securities Act”), and outside the United States pursuant to Regulation S under the Securities Act. This press release does not constitute an offer to sell or the solicitation of an offer to buy any of the notes, nor shall there be any sale of notes in any jurisdiction in which such offer, solicitation or sale would be unlawful. The notes will not be registered under the Securities Act or the securities laws of any other jurisdiction and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements.

About Clean Harbors

Clean Harbors (NYSE: CLH) is North America’s leading provider of environmental and industrial services. The Company serves a diverse customer base, including a majority of Fortune 500 companies. Its customer base spans a number of industries, including chemical, manufacturing and refining, as well as numerous government agencies. These customers rely on Clean Harbors to deliver a broad range of services such as end-to-end hazardous waste management, emergency spill response, industrial cleaning and maintenance, and recycling services. Through its Safety-Kleen subsidiary, Clean Harbors also is a leading provider of parts washers and environmental services to commercial, industrial and automotive customers, as well as North America’s largest re-refiner and recycler of used oil. Founded in 1980 and based in Massachusetts, Clean Harbors operates in the United States, Canada, Mexico, Puerto Rico and India.

Safe Harbor Statement

Clean Harbors • 42 Longwater Drive • PO Box 9149 • Norwell, Massachusetts 02061-9149 • 800.282.0058 • www.cleanharbors.com

expectations of Clean Harbors’ management as of the date of this press release only and are subject to certain risks and uncertainties that could cause actual results to differ materially, including, without limitation: the risk that the Company will not sell the notes, complete the Acquisitions or apply the net proceeds as indicated because of adverse market conditions or otherwise; risks associated with the Company’s ability to complete the Acquisitions, integrate the Acquisitions into the Company’s existing operations, and/or realize the expected benefits from the Acquisitions; operational and safety risks; risks relating to the failure of new or existing technologies; risks associated with the use of artificial intelligence; cybersecurity risks; the occurrence of natural disasters or other catastrophic events, as well as their residual macroeconomic effects; risks associated with retaining and hiring key personnel; environmental liability and product liability risks relating to hazardous waste management and other components of the Company’s business; negative economic, industry or other developments, including market volatility or economic downturns; risks associated with management’s assumptions relating to expansion of the Company’s landfills; reductions in the demand for emergency response services at industrial facilities or on roadways, railways or waterways, and other remedial projects and regulatory developments; reductions in the demand for oil products and automotive services and volatility in oil prices in the markets the Company serves; changes in statutory and regulatory requirements and risks relating to extensive environmental laws and regulations; risks associated with existing and potential litigation; risks associated with the Company’s identification and execution of strategic capital expenditures, acquisitions and divestitures and their related liabilities; risks relating to the availability and sufficiency of the Company’s insurance coverage, self-insurance, surety bonds, letters of credit and other forms of financial assurance; the impact of new tax legislation or changes in tax regulations and interpretations; the imposition of trade sanctions or tariffs; fluctuations in interest rates and foreign currency exchange rates; risks relating to the Company’s indebtedness and covenants in its debt agreements; risks associated with certain anti-takeover provisions under the Massachusetts Business Corporation Act and the Company’s By-Laws, and those items identified as “Risk Factors” in Clean Harbors’ most recently filed reports on Form 10-K and Form 10-Q. Forward-looking statements are neither historical facts nor assurances of future performance. Therefore, readers are cautioned not to place undue reliance on these forward-looking statements. Clean Harbors undertakes no obligation to revise or publicly release the results of any revision to these forward-looking statements other than through its filings with the Securities and Exchange Commission.

Contacts:

Eric J. Dugas

Jim Buckley

EVP and Chief Financial Officer

SVP Investor Relations

Clean Harbors, Inc.

781.792.5100

InvestorRelations@cleanharbors.com

Buckley.James@cleanharbors.com

Clean Harbors • 42 Longwater Drive • PO Box 9149 • Norwell, Massachusetts 02061-9149 • 800.282.0058 • www.cleanharbors.com

EX-99.2

Filename: clh-notesofferingpricingre.htm · Sequence: 3

Document

EXHIBIT 99.2

Press Release

Clean Harbors Prices Offering of Senior Notes Due 2034

NORWELL, Mass. – September 17, 2026 – Clean Harbors, Inc. (“Clean Harbors” or the “Company”) (NYSE: CLH), announced today that it has priced a private offering of $600 million of senior notes due 2034 (the “notes”).

The notes, which carry an interest rate of 6.250%, were priced for purposes of resale at 100.000% of their aggregate principal amount. The issuance and sale of the notes is expected to close on or about October 1, 2026, subject to customary closing conditions. The Company intends to use the net proceeds from the offering of notes to finance the purchase price of the Company’s previously announced acquisition of EnviroServe, a national provider of environmental and waste management services (the “EnviroServe Acquisition”), and the remainder of the net proceeds to repay the borrowings under its revolving credit facility that were incurred to partially finance the purchase price of the Company’s previously announced acquisition of ES&H (the “ES&H Acquisition” and, together with the EnviroServe Acquisition, the “Acquisitions”). There can be no assurance that the Acquisitions will be completed on the terms the Company anticipates, in a timely manner or at all. The consummation of the offering of notes is not contingent on the completion of the Acquisitions and, if either Acquisition is not completed, the Company intends to use the remaining net proceeds for general corporate purposes.

About Clean Harbors

Clean Harbors • 42 Longwater Drive • PO Box 9149 • Norwell, Massachusetts 02061-9149 • 800.282.0058 • www.cleanharbors.com

Safe Harbor Statement

Any statements contained herein that are not historical facts are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are generally identifiable by use of the words “believes,” “expects,” “intends,” “anticipates,” “plans to,” “seeks,” “will,” “should,” “estimates,” “projects,” “may,” “likely,” “potential,” “outlook” or similar expressions. Such statements include, but are not limited to, statements about the closing of the offering of notes, the Company’s intended use of proceeds therefrom and the Acquisitions. Such statements are based upon the beliefs and expectations of Clean Harbors’ management as of the date of this press release only and are subject to certain risks and uncertainties that could cause actual results to differ materially, including, without limitation: the risk that the Company will not sell the notes, complete the Acquisitions or apply the net proceeds as indicated because of adverse market conditions or otherwise; risks associated with the Company’s ability to complete the Acquisitions, integrate the Acquisitions into the Company’s existing operations, and/or realize the expected benefits from the Acquisitions; operational and safety risks; risks relating to the failure of new or existing technologies; risks associated with the use of artificial intelligence; cybersecurity risks; the occurrence of natural disasters or other catastrophic events, as well as their residual macroeconomic effects; risks associated with retaining and hiring key personnel; environmental liability and product liability risks relating to hazardous waste management and other components of the Company’s business; negative economic, industry or other developments, including market volatility or economic downturns; risks associated with management’s assumptions relating to expansion of the Company’s landfills; reductions in the demand for emergency response services at industrial facilities or on roadways, railways or waterways, and other remedial projects and regulatory developments; reductions in the demand for oil products and automotive services and volatility in oil prices in the markets the Company serves; changes in statutory and regulatory requirements and risks relating to extensive environmental laws and regulations; risks associated with existing and potential litigation; risks associated with the Company’s identification and execution of strategic capital expenditures, acquisitions and divestitures and their related liabilities; risks relating to the availability and sufficiency of the Company’s insurance coverage, self-insurance, surety bonds, letters of credit and other forms of financial assurance; the impact of new tax legislation or changes in tax regulations and interpretations; the imposition of trade sanctions or tariffs; fluctuations in interest rates and foreign currency exchange rates; risks relating to the Company’s indebtedness and covenants in its debt agreements; risks associated with certain anti-takeover provisions under the Massachusetts Business Corporation Act and the Company’s By-Laws, and those items identified as “Risk Factors” in Clean Harbors’ most recently filed reports on Form 10-K and Form 10-Q. Forward-looking statements are neither historical facts nor assurances of future performance. Therefore, readers are cautioned not to place undue reliance on these forward-looking statements. Clean Harbors undertakes no obligation to revise or publicly release the results of any revision to these forward-looking statements other than through its filings with the Securities and Exchange Commission.

Clean Harbors • 42 Longwater Drive • PO Box 9149 • Norwell, Massachusetts 02061-9149 • 800.282.0058 • www.cleanharbors.com

Contacts:

Eric J. Dugas

Jim Buckley

EVP and Chief Financial Officer

SVP Investor Relations

Clean Harbors, Inc.

781.792.5100

InvestorRelations@cleanharbors.com

Buckley.James@cleanharbors.com

Clean Harbors • 42 Longwater Drive • PO Box 9149 • Norwell, Massachusetts 02061-9149 • 800.282.0058 • www.cleanharbors.com

GRAPHIC

Filename: image.jpg · Sequence: 7

Binary file (9996 bytes)

Download image.jpg

GRAPHIC

Filename: imageb.jpg · Sequence: 8

Binary file (9996 bytes)

Download imageb.jpg

XML — IDEA: XBRL DOCUMENT

XML

Filename: R1.htm · Sequence: 10

v3.26.3

Cover

Sep. 17, 2026

Cover [Abstract]

Document Type

8-K

Document Period End Date

Sep. 17, 2026

Entity Registrant Name

CLEAN HARBORS, INC

Entity Central Index Key

0000822818

Amendment Flag

false

Entity Incorporation, State or Country Code

Entity File Number

001-34223

Entity Tax Identification Number

04-2997780

Entity Address, Address Line One

42 Longwater Drive

Entity Address, City or Town

Norwell

Entity Address, State or Province

Entity Address, Postal Zip Code

02061-9149

City Area Code

781

Local Phone Number

792-5000

Written Communications

false

Soliciting Material

false

Pre-commencement Tender Offer

false

Pre-commencement Issuer Tender Offer

false

Entity Emerging Growth Company

false

Title of 12(b) Security

Common Stock, $0.01 par value

Trading Symbol

CLH

Security Exchange Name

NYSE

- Definition

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

+ References

No definition available.

+ Details

Name:

dei_AmendmentFlag

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Area code of city

+ References

No definition available.

+ Details

Name:

dei_CityAreaCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Cover page.

+ References

No definition available.

+ Details

Name:

dei_CoverAbstract

Namespace Prefix:

dei_

Data Type:

xbrli:stringItemType

Balance Type:

Period Type:

duration

- Definition

For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

+ References

No definition available.

+ Details

Name:

dei_DocumentPeriodEndDate

Namespace Prefix:

dei_

Data Type:

xbrli:dateItemType

Balance Type:

Period Type:

duration

- Definition

The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

+ References

No definition available.

+ Details

Name:

dei_DocumentType

Namespace Prefix:

dei_

Data Type:

dei:submissionTypeItemType

Balance Type:

Period Type:

duration

- Definition

Address Line 1 such as Attn, Building Name, Street Name

+ References

No definition available.

+ Details

Name:

dei_EntityAddressAddressLine1

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the City or Town

+ References

No definition available.

+ Details

Name:

dei_EntityAddressCityOrTown

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Code for the postal or zip code

+ References

No definition available.

+ Details

Name:

dei_EntityAddressPostalZipCode

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Name of the state or province.

+ References

No definition available.

+ Details

Name:

dei_EntityAddressStateOrProvince

Namespace Prefix:

dei_

Data Type:

dei:stateOrProvinceItemType

Balance Type:

Period Type:

duration

- Definition

A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityCentralIndexKey

Namespace Prefix:

dei_

Data Type:

dei:centralIndexKeyItemType

Balance Type:

Period Type:

duration

- Definition

Indicate if registrant meets the emerging growth company criteria.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityEmergingGrowthCompany

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

+ References

No definition available.

+ Details

Name:

dei_EntityFileNumber

Namespace Prefix:

dei_

Data Type:

dei:fileNumberItemType

Balance Type:

Period Type:

duration

- Definition

Two-character EDGAR code representing the state or country of incorporation.

+ References

No definition available.

+ Details

Name:

dei_EntityIncorporationStateCountryCode

Namespace Prefix:

dei_

Data Type:

dei:edgarStateCountryItemType

Balance Type:

Period Type:

duration

- Definition

The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityRegistrantName

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b-2

+ Details

Name:

dei_EntityTaxIdentificationNumber

Namespace Prefix:

dei_

Data Type:

dei:employerIdItemType

Balance Type:

Period Type:

duration

- Definition

Local phone number for entity.

+ References

No definition available.

+ Details

Name:

dei_LocalPhoneNumber

Namespace Prefix:

dei_

Data Type:

xbrli:normalizedStringItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 13e

-Subsection 4c

+ Details

Name:

dei_PreCommencementIssuerTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14d

-Subsection 2b

+ Details

Name:

dei_PreCommencementTenderOffer

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Title of a 12(b) registered security.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection b

+ Details

Name:

dei_Security12bTitle

Namespace Prefix:

dei_

Data Type:

dei:securityTitleItemType

Balance Type:

Period Type:

duration

- Definition

Name of the Exchange on which a security is registered.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 12

-Subsection d1-1

+ Details

Name:

dei_SecurityExchangeName

Namespace Prefix:

dei_

Data Type:

dei:edgarExchangeCodeItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as soliciting material pursuant to Rule 14a-12 under the Exchange Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Exchange Act

-Number 240

-Section 14a

-Subsection 12

+ Details

Name:

dei_SolicitingMaterial

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration

- Definition

Trading symbol of an instrument as listed on an exchange.

+ References

No definition available.

+ Details

Name:

dei_TradingSymbol

Namespace Prefix:

dei_

Data Type:

dei:tradingSymbolItemType

Balance Type:

Period Type:

duration

- Definition

Boolean flag that is true when the Form 8-K filing is intended to satisfy the filing obligation of the registrant as written communications pursuant to Rule 425 under the Securities Act.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Securities Act

-Number 230

-Section 425

+ Details

Name:

dei_WrittenCommunications

Namespace Prefix:

dei_

Data Type:

xbrli:booleanItemType

Balance Type:

Period Type:

duration