Form 8-K

8-K — CLEAN HARBORS INC

Accession: 0000822818-26-000031

Filed: 2026-07-29

Period: 2026-07-29

CIK: 0000822818

SIC: 4955 (HAZARDOUS WASTE MANAGEMENT)

Item: Results of Operations and Financial Condition

Item: Financial Statements and Exhibits

Documents

8-K — clh-20260729.htm (Primary)

EX-99.1 (clh-q22026pressrelease.htm)

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GRAPHIC — CLEAN HARBORS LOGO (image.jpg)

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8-K — 10-Q

8-K (Primary)

Filename: clh-20260729.htm · Sequence: 1

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0000822818false00008228182026-07-292026-07-29

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): July 29, 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 2.02 Results of Operations and Financial Condition

On July 29, 2026, Clean Harbors, Inc. (the “Company”) issued a press release announcing the Company’s results of operations for the second quarter ended June 30, 2026. A copy of that press release is furnished with this report as Exhibit 99.1.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits. The following exhibits are being furnished herewith:

Exhibit No. Description

99.1

Press Release dated July 29, 2026

104 The cover page from this Current Report on Form 8-K, formatted in iXBRL (Inline eXtensible Business Reporting Language)

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)

July 29, 2026 /s/ Eric J. Dugas

Executive Vice President and Chief Financial Officer

EX-99.1

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Document

EXHIBIT 99.1

Press Release

Clean Harbors Announces Second-Quarter 2026 Financial Results

•Increases Q2 Revenue 12% to a Record $1.74 Billion Driven by Both Operating Segments

•Generates 34% Increase in Q2 Net Income to $170.5 Million, or EPS of $3.22

•Achieves 22% Growth in Q2 Adjusted EBITDA to $409.0 Million; Expands Adjusted EBITDA Margin YoY by 190 Basis Points to 23.6%

•Announces Ten-Year Disposal Contract With Estimated Value of $600 Million With Customer Who is Expanding Its U.S. Manufacturing

•Expands Field Services Through Planned $305 Million Acquisition of ES&H

•Raises 2026 Guidance for Adjusted EBITDA and Adjusted Free Cash Flow

NORWELL, Mass. – July 29, 2026 – Clean Harbors, Inc. (“Clean Harbors” or the “Company”) (NYSE: CLH), the leading provider of environmental and industrial services throughout North America, today announced financial results for the second quarter ended June 30, 2026.

“Our record second-quarter results demonstrate the substantial momentum we achieved in both of our operating segments,” said Mike Battles, Co-Chief Executive Officer. “Our Environmental Services (ES) segment benefited from a combination of healthy volumes into our disposal and recycling network, remediation projects, PFAS-related work and our strategic pricing initiatives to offset inflation and fuel costs. Within our Safety-Kleen Sustainability Solutions (SKSS) segment, a sharp uptick in market pricing for our re-refined products drove significant profitability during the quarter. In addition, our team continues to achieve commendable industry-leading safety results with the Company’s year-to-date Total Recordable Incident Rate at 0.46.”

Second-Quarter 2026 Results

Revenues increased 12% to $1.74 billion, compared with $1.55 billion in the same period of 2025. Income from operations rose 28% to $268.9 million, compared with $210.3 million in the second quarter of 2025.

Net income increased 34% to $170.5 million, or $3.22 per diluted share, compared with $126.9 million, or $2.36 per diluted share, for the same period in 2025.

Adjusted EBITDA (see description and reconciliation below) increased 22% to $409.0 million from $336.2 million for the same period in 2025.

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

Second-Quarter 2026 Segment Review

“Our ES segment delivered its 17th consecutive quarter of year-over-year Adjusted EBITDA margin expansion with a margin of 27.9%,” said Eric Gerstenberg, Co-Chief Executive Officer. “Within the segment, Technical Services grew revenue 18% on strong demand for disposal and recycling services. We continued to win base business and sizeable projects, including a large PFAS-related filtration project that resulted from previous emergency response work. Safety-Kleen Environmental Services’ revenue in the segment increased 11%, driven by pricing and growth in its core offerings, including containerized waste collection and vacuum services. Incineration utilization, including the new Kimball incinerator, was 91% compared with 86% a year ago. At the same time, landfill volumes rose 7% in the quarter. Field Services revenue grew 3% year-over-year, despite a difficult comp with large emergency response (ER) projects in the prior period. Overall, it was an exceptional quarter for this segment, reflecting our ability to capture strong, sustained demand trends that we expect to remain intact as we move into the second half of the year.”

“SKSS segment revenue increased 41% in Q2 and Adjusted EBITDA was 143% higher, with segment margin up more than 70% from the year ago period,” Battles said. “This performance reflects market conditions resulting from major global supply disruptions of refined products. We also saw the benefit of ongoing strategic initiatives including producing Group III gallons and selling more blended volume. Our collections team also did a remarkable job actively managing the front end of our re-refining spread, balancing both collection volumes and costs. We gathered 61 million gallons of waste oil while continuing to increase revenues generated from our used oil collection services compared with a year ago. The SKSS segment executed well in the quarter and these supply conditions are expected to extend into the third quarter.”

Awarded Ten-Year Disposal Contract

Clean Harbors also announced today that it recently won a significant, ten-year disposal contract with a customer that is expanding its U.S. manufacturing operations. The contract, which involves incineration waste and complex wastewater volumes, carries an estimated value of $600 million over the life of the contract with options to expand in scope. The contract will commence in the fourth quarter of this year and is expected to reach full capacity in 2030, based on the ramp-up of multiple manufacturing sites by the customer.

“We believe this multi-year contract demonstrates our unique capabilities and versatility to safely process large volumes of variable waste streams,” Gerstenberg said. “This customer selected Clean Harbors as a long-term partner because of the vast capabilities, scale and redundancy of our disposal network. This contract also reflects current U.S. expansion trends due to reshoring. Given the widespread capabilities of our assets, we expect to pursue opportunities for new contracts and to expand our relationships with existing customers who are growing their North American manufacturing presence.”

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

Agreement to Acquire ES&H to Bolster Field Services

Clean Harbors also has entered into a definitive agreement to acquire ES&H, a leading regional provider of environmental and ER services in the Gulf region for $305 million in cash. The acquisition is expected to close in the second half of 2026, subject to regulatory approval and other customary closing conditions.

“ES&H is a recognized leader in the Gulf region, and its addition is expected to expand our Field Services business,” Battles said. “We expect to derive attractive shareholder returns from this transaction as ES&H has built a well-established brand over its 30-year history. The company has a strong reputation as a great resource for on-water response, and like Clean Harbors, carries the Coast Guard’s highest Oil Spill Response Organization (OSRO) classification. Their talented employees, geographic footprint and equipment fleet will enhance our existing Field Services business.”

Headquartered in Louisiana, ES&H has 13 service branches, the majority of which are coastal locations that support its maritime services, which complement Clean Harbors’ existing offerings. The company’s primary offerings include emergency response, field services and environmental impact management services for customers across multiple industries. ES&H’s annual base revenues are approximately $90 million, generating annual Adjusted EBITDA of approximately $30 million. Clean Harbors expects the acquisition to generate cost synergies of approximately $5 million after the first full year of operations, which equates to a post-synergy acquisition multiple of 8.7 times.

Business Outlook

“We currently continue to see positive demand trends across both operating segments,” Gerstenberg said. “The U.S. Manufacturing PMI was above 50 – indicating nationwide expansion – for the first six months of 2026. Our recent discussions with customers suggest a strengthening U.S. economy will support greater volumes into our network and drive demand for our various services. We believe that ongoing reshoring is creating opportunities for us to add new customer locations and waste streams. Our PFAS pipeline continues its growth in the U.S. and Canada, including both private and government customers. Our Field Services business is currently working on multiple large emergency response events that should support Q3 growth in that business and further enhance our reputation as a national go-to provider for environmental emergencies. Within Industrial Services, we are introducing a new strategic offering for data centers that we expect will generate growth in that business in the years ahead. For SKSS, the business continues to be well-managed at both ends of our spread while operating in a favorable demand environment. Overall, we expect to realize strong operating results in both segments in the second half on our way to delivering record results for the full year.”

Financial Guidance

In the third quarter of 2026, Clean Harbors expects Adjusted EBITDA to grow 24% to 28% year over year. Based on its first-half performance and current market conditions, Clean Harbors is raising the midpoint of its

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

2026 Adjusted EBITDA guidance by $110 million and the midpoint of its adjusted free cash flow guidance by $30 million. For the full year, Clean Harbors now expects:

•Adjusted EBITDA in the range of $1.35 billion to $1.41 billion, with a midpoint of $1.38 billion. This Adjusted EBITDA range is based on anticipated GAAP net income in the range of $481 million to $531 million.

•Adjusted free cash flow in the range of $520 million to $580 million, with a midpoint of $550 million. This range is based on anticipated net cash from operating activities in the range of $890 million to $1,010 million.

Non-GAAP Results:

Adjusted EBITDA Reconciliation

Clean Harbors reports Adjusted EBITDA, which is a non-GAAP financial measure and should not be considered an alternative to net income or other measurements under generally accepted accounting principles (GAAP) but viewed only as a supplement to those measurements. Adjusted EBITDA is not calculated identically by all companies, and therefore the Company’s measurement of Adjusted EBITDA may not be comparable to similarly titled measures reported by other companies. Clean Harbors believes that Adjusted EBITDA provides additional useful information to investors because the Company’s management routinely evaluates the performance of its businesses based upon levels of Adjusted EBITDA. The Company defines Adjusted EBITDA as described in the following reconciliation showing the differences between reported net income and Adjusted EBITDA for the three and six months ended June 30, 2026 and 2025 (in thousands, except percentages):

Three Months Ended Six Months Ended

June 30, 2026 June 30, 2025 June 30, 2026 June 30, 2025

Net income $ 170,464 $ 126,905 $ 233,665 $ 185,585

Accretion of environmental liabilities 3,502 3,591 7,044 7,211

Stock-based compensation 14,818 6,063 24,396 13,698

Depreciation and amortization 121,807 116,285 237,606 228,265

Other (income) expense, net (430) 603 301 1,535

Interest expense, net of interest income 37,208 37,106 71,062 73,183

Provision for income taxes 61,655 45,684 82,804 61,614

Adjusted EBITDA $ 409,024 $ 336,237 $ 656,878 $ 571,091

Adjusted EBITDA Margin 23.6 % 21.7 % 20.6 % 19.2 %

Adjusted Free Cash Flow Reconciliation

Clean Harbors reports adjusted free cash flow, a non-GAAP measure, which it considers to be a measurement of liquidity that provides useful information to investors about its ability to generate cash. The Company defines adjusted free cash flow as net cash from operating activities less additions to property, plant and equipment plus proceeds from sale and disposal of fixed assets. When necessary, the Company adjusts for the cash impact of

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

items derived from non-operating activities. Additionally, adjusted free cash flow excludes significant strategic growth investments, as they are not indicative of free cash flow for the current period. Adjusted free cash flow should not be considered an alternative to net cash from operating activities or other measurements under GAAP. Adjusted free cash flow is not calculated identically by all companies, and therefore the Company’s measurement of adjusted free cash flow may not be comparable to similarly titled measures reported by other companies.

An itemized reconciliation between reported GAAP net cash from operating activities and adjusted free cash flow is as follows (in thousands):

Three Months Ended Six Months Ended

June 30, 2026 June 30, 2025 June 30, 2026 June 30, 2025

Net cash from operating activities $ 239,173 $ 208,040 $ 245,470 $ 209,645

Additions to property, plant and equipment (126,195) (90,029) (224,638) (208,724)

Cash investments in strategic growth projects 20,535 12,436 35,322 12,436

Proceeds from sale and disposal of fixed assets 2,172 2,720 3,694 4,063

Adjusted free cash flow $ 135,685 $ 133,167 $ 59,848 $ 17,420

Adjusted EBITDA Guidance Reconciliation

An itemized reconciliation between projected GAAP net income and projected Adjusted EBITDA is as follows (in millions):

For the Year Ending December 31, 2026

Projected GAAP net income $481 to $531

Adjustments:

Accretion of environmental liabilities 16 to 15

Stock-based compensation 48 to 51

Depreciation and amortization 485 to 475

Interest expense, net 151 to 146

Provision for income taxes 169 to 192

Projected Adjusted EBITDA $1,350 to $1,410

Adjusted Free Cash Flow Guidance Reconciliation

An itemized reconciliation between projected GAAP net cash from operating activities and projected adjusted free cash flow is as follows (in millions). The Company excludes significant strategic growth investments,

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

which the Company expects to realize future long-term benefits from, as they are not indicative of free cash flow generation for the current period.

For the Year Ending December 31, 2026

Projected net cash from operating activities $890 to $1,010

Additions to property, plant and equipment (505) to (565)

Cash investments in strategic growth projects 120 to 120

Proceeds from sale and disposal of fixed assets 15 to 15

Projected adjusted free cash flow $520 to $580

Conference Call Information

Clean Harbors will conduct a conference call for investors today at 9:00 a.m. (ET) to discuss the information contained in this press release. During the call, management will discuss Clean Harbors’ financial results, business outlook and growth strategy. Investors who wish to listen to the webcast and view the accompanying slides should visit the Investor Relations section of the Company’s website at www.cleanharbors.com. The live call also can be accessed by dialing 877.709.8155 or 201.689.8881 prior to the start time. The webcast will be archived on the Company’s website after the conclusion of the live event.

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. For more information, visit 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 may include, but are not limited to, statements about the Company’s future financial and operating results, plans, strategy, objectives and goals, strategic initiatives, cost management initiatives, pricing and productivity initiatives, contingent liabilities, interest expense, liquidity, business, economic and market conditions, trends, customer demand, expectations regarding new customer contracts, impacts of tariffs and new legislation, acquisitions, growth opportunities and investments, expectations, challenges and other statements that are not historical facts. Such statements are based upon the beliefs and expectations of Clean Harbors’

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

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: 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, which may be viewed in the “Investors” section of Clean Harbors’ website at 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

CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS

(in thousands, except per share amounts)

Three Months Ended Six Months Ended

June 30, June 30,

2026 2025 2026 2025

Revenues $ 1,735,005 $ 1,549,854 $ 3,194,542 $ 2,981,804

Cost of revenues 1,126,225 1,033,497 2,140,345 2,055,381

Selling, general and administrative expenses 214,574 186,183 421,715 369,030

Accretion of environmental liabilities 3,502 3,591 7,044 7,211

Depreciation and amortization 121,807 116,285 237,606 228,265

Income from operations 268,897 210,298 387,832 321,917

Other income (expense), net 430 (603) (301) (1,535)

Interest expense, net (37,208) (37,106) (71,062) (73,183)

Income before provision for income taxes 232,119 172,589 316,469 247,199

Provision for income taxes 61,655 45,684 82,804 61,614

Net income $ 170,464 $ 126,905 $ 233,665 $ 185,585

Earnings per share:

Basic $ 3.23 $ 2.37 $ 4.42 $ 3.46

Diluted $ 3.22 $ 2.36 $ 4.41 $ 3.44

Shares used to compute earnings per share - Basic 52,806 53,593 52,843 53,675

Shares used to compute earnings per share - Diluted 52,961 53,799 53,005 53,895

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

CLEAN HARBORS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(in thousands)

June 30, 2026 December 31, 2025

Current assets: (unaudited)

Cash and cash equivalents $ 408,357 $ 826,315

Short-term marketable securities 108,361 127,363

Accounts receivable, net 1,276,620 1,044,137

Unbilled accounts receivable 186,764 160,888

Inventories and supplies 382,935 372,088

Prepaid expenses and other current assets 109,203 116,452

Total current assets 2,472,240 2,647,243

Property, plant and equipment, net 2,636,955 2,541,067

Other assets:

Operating lease right-of-use assets 257,518 255,084

Goodwill 1,672,635 1,479,050

Permits and other intangibles, net 749,111 653,027

Other long-term assets 48,574 48,585

Total other assets 2,727,838 2,435,746

Total assets $ 7,837,033 $ 7,624,056

Current liabilities:

Current portion of long-term debt $ 12,600 $ 12,600

Accounts payable 518,186 506,592

Deferred revenue 84,038 81,529

Accrued expenses and other current liabilities 442,435 441,788

Current portion of closure, post-closure and remedial liabilities 22,774 19,112

Current portion of operating lease liabilities 80,291 75,226

Total current liabilities 1,160,324 1,136,847

Other liabilities:

Closure and post-closure liabilities, less current portion 124,554 125,038

Remedial liabilities, less current portion 83,512 86,547

Long-term debt, less current portion 2,759,327 2,763,563

Operating lease liabilities, less current portion 182,077 184,308

Deferred tax liabilities 384,008 384,207

Other long-term liabilities 214,809 197,886

Total other liabilities 3,748,287 3,741,549

Total stockholders’ equity, net

2,928,422 2,745,660

Total liabilities and stockholders’ equity

$ 7,837,033 $ 7,624,056

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

CLEAN HARBORS, INC. AND SUBSIDIARIES

UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS

(in thousands)

Six Months Ended

June 30, 2026 June 30, 2025

Cash flows from operating activities:

Net income $ 233,665 $ 185,585

Adjustments to reconcile net income to net cash from operating activities:

Depreciation and amortization 237,606 228,265

Allowance for doubtful accounts 5,951 3,249

Amortization of deferred financing costs and debt discount 2,610 3,352

Accretion of environmental liabilities 7,044 7,211

Changes in environmental liability estimates (2,061) (8,954)

Other expense, net 301 1,535

Stock-based compensation 24,396 13,698

Environmental expenditures (7,079) (7,051)

Changes in assets and liabilities, net of acquisitions:

Accounts receivable and unbilled accounts receivable (262,255) (116,399)

Inventories and supplies (11,679) 2,952

Other current and non-current assets 10,057 (13,395)

Accounts payable 8,859 (36,035)

Other current and long-term liabilities (1,945) (54,368)

Net cash from operating activities 245,470 209,645

Cash flows used in investing activities:

Additions to property, plant and equipment (224,638) (208,724)

Proceeds from sale and disposal of fixed assets 3,694 4,063

Acquisitions, net of cash acquired (357,593) —

Additions to intangible assets including costs to obtain or renew permits (987) (777)

Purchases of available-for-sale securities (25,853) (45,622)

Proceeds from sale of available-for-sale securities 44,857 50,318

Net cash used in investing activities (560,520) (200,742)

Cash flows used in financing activities:

Change in uncashed checks (5,507) (2,767)

Tax payments related to withholdings on vested restricted stock (11,804) (10,456)

Repurchases of common stock (52,133) (67,001)

Proceeds from employee stock purchase plan 3,611 3,360

Deferred financing costs paid (691) —

Payments on finance leases (25,422) (16,754)

Principal payments on debt (6,300) (7,551)

Net cash used in financing activities (98,246) (101,169)

Effect of exchange rate change on cash (4,662) 5,260

Decrease in cash and cash equivalents (417,958) (87,006)

Cash and cash equivalents, beginning of period 826,315 687,192

Cash and cash equivalents, end of period $ 408,357 $ 600,186

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

Supplemental information:

Cash payments for interest and income taxes:

Interest paid $ 75,394 $ 76,570

Income taxes paid, net of refunds 63,801 64,534

Non-cash investing activities:

Property, plant and equipment accrued 40,544 25,156

ROU assets obtained in exchange for operating lease liabilities 41,492 34,867

ROU assets obtained in exchange for finance lease liabilities 45,495 57,802

Supplemental Segment Data (in thousands)

Three Months Ended

Revenue June 30, 2026 June 30, 2025

Third-Party Revenues Intersegment Revenues (Expenses), net Direct Revenues Third-Party Revenues Intersegment Revenues (Expenses), net Direct Revenues

Environmental Services $ 1,444,532 $ 12,031 $ 1,456,563 $ 1,330,059 $ 21,976 $ 1,352,035

Safety-Kleen Sustainability Solutions 290,473 (12,031) 278,442 219,706 (21,976) 197,730

Corporate — — — 89 — 89

Total $ 1,735,005 $ — $ 1,735,005 $ 1,549,854 $ — $ 1,549,854

Six Months Ended

Revenue June 30, 2026 June 30, 2025

Third-Party Revenues Intersegment Revenues (Expenses), net Direct Revenues Third-Party Revenues Intersegment Revenues (Expenses), net Direct Revenues

Environmental Services $ 2,686,980 $ 22,109 $ 2,709,089 $ 2,537,097 $ 24,051 $ 2,561,148

Safety-Kleen Sustainability Solutions 507,562 (22,109) 485,453 444,521 (24,051) 420,470

Corporate — — — 186 — 186

Total $ 3,194,542 $ — $ 3,194,542 $ 2,981,804 $ — $ 2,981,804

Three Months Ended Six Months Ended

Adjusted EBITDA June 30, 2026 June 30, 2025 June 30, 2026 June 30, 2025

Environmental Services $ 406,104 $ 376,194 $ 696,505 $ 650,785

Safety-Kleen Sustainability Solutions 92,993 38,313 125,974 66,565

Corporate (90,073) (78,270) (165,601) (146,259)

Total $ 409,024 $ 336,237 $ 656,878 $ 571,091

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

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v3.26.1

Cover

Jul. 29, 2026

Cover [Abstract]

Document Type

8-K

Document Period End Date

Jul. 29, 2026

Entity Registrant Name

CLEAN HARBORS, INC

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

Entity Central Index Key

0000822818

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Cover page.

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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.

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