Clean Harbors Prices Offering of Senior Secured Notes; Increases Deal Size to $250 Million

Norwell, MA – March 21, 2011 – Clean Harbors, Inc. (NYSE: CLH), the leading provider of environmental, energy and industrial services throughout North America, today announced that it has priced a follow-on offering of $250.0 million in senior secured notes due 2016 (the “Notes”). The offering size was increased from the previously announced $200.0 million.

The Notes, which carry an interest rate of 7.625%, were priced at 104.5% of the aggregate principal amount, representing a yield of 6.132%. The transaction is expected to close on or about March 24, 2011, subject to customary closing conditions. The Company intends to use the net proceeds from the offering of the Notes, together with a portion of the Company’s available cash, to pay the purchase price for the Company’s previously announced proposed acquisition of Badger Daylighting Ltd. and related transaction fees and expenses. If such proposed acquisition is not consummated, the Company plans to use the net proceeds from the offering for general corporate purposes, which may include other acquisitions.

The Notes are being offered in the United States to 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 shall not constitute an offer to sell or the solicitation of an offer to buy, nor shall there be any sale of, the Notes in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such jurisdiction. The Notes will not be registered under the Securities Act and may not be offered or sold in the United States absent registration or an applicable exemption from registration requirements.

About Clean Harbors, Inc.

Clean Harbors is the leading provider of environmental, energy and industrial services throughout North America. The Company serves over 50,000 customers, including a majority of the Fortune 500 companies, thousands of smaller private entities and numerous federal, state, provincial and local governmental agencies. Headquartered in Norwell, Massachusetts, Clean Harbors has more than 175 locations, including over 50 waste management facilities, throughout North America in 36 U.S. states, seven Canadian provinces, Mexico and Puerto Rico. The Company also operates international locations in Bulgaria, China, Singapore, Sweden, Thailand and the United Kingdom.

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. Such statements may include, but are not limited to, statements about the Company’s plans to offer senior secured notes and other statements that are not historical facts. Such statements are based upon the beliefs and expectations of Clean Harbors’ management as of this date only and are subject to certain risks and uncertainties that could cause actual results to differ materially, including, without limitation, those items identified as “risk factors” in the Company’s most recently filed Form 10-K and Form 10-Q. Therefore, readers are cautioned not to place undue reliance on these forward-looking statements. The Company undertakes no obligation to revise or publicly release any revision to these forward-looking statements other than through its various filings with the Securities and Exchange Commission.

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