Company: CLH
Filing Date: 2025-04-11
Form Type: DEF 14A
Source: 0000822818-25-000011
Chunk: 0

Company: CLEAN HARBORS INC
Filing Date: 2025-04-11
Form: DEF 14A
Chunk 0
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### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A
<div align='center'>Proxy Statement Pursuant to Section 14(a) of

the Securities Exchange Act of 1934 (Amendment No. )

Filed by the Registrant Filed by a Party other than the Registrant</div>

| Check the appropriate box: |     |                                                                                 |
|                            |     | Preliminary Proxy Statement                                                     |
|                            |     | Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2)) |
|                            |     | Definitive Proxy Statement                                                      |
|                            |     | Definitive Additional Materials                                                 |
|                            |     | Soliciting Material under §240.14a-12                                           |

| Clean Harbors, Inc. |

| (Name of Registrant as Specified In Its Charter)                         |
| (Name of Person(s) Filing Proxy Statement, if other than the Registrant) |

| Payment of Filing Fee (Check all the boxes that apply): |     |                                                                                                      |
|                                                         |     | No fee required.                                                                                     |
|                                                         |     | Fee paid previously with preliminary materials.                                                      |
|                                                         |     | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11. |

April 11, 2025

Corporate Headquarters

42 Longwater Drive

Norwell, Massachusetts 02061

Tel. 781-792-5000

To Our Fellow Shareholders:

On behalf of the Board of Directors, it is my pleasure to invite you to attend the 2025 annual meeting of shareholders, to be held at 10:00 a.m., local time, on Wednesday, May 21, 2025, at our company’s training facility at 101 Philip Drive, Norwell, Massachusetts, located adjacent to our company’s headquarters.

Information about the annual meeting is presented on the following pages. In addition to the formal items of business, the meeting will include a report by members of management on our company operations. You will have an opportunity to ask questions of our management team if you attend the meeting in person.

For the 2025 annual meeting, we are again using the “notice and access” method of providing proxy materials via the internet. On or about April 11, 2025, we will be