Clean Harbors Prices Follow-On Offering of Common Stock

NORWELL, Mass.--(Business Wire)--
Clean Harbors, Inc. (NASDAQ: CLHB), the leading provider of
environmental and hazardous waste management services throughout North
America, today announced the pricing of its previously announced
follow-on public offering of 2,500,000 shares of its common stock at a
price of $63.75 per share. All shares are being offered by the
Company. The Company expects to deliver the shares on April 29, 2008.
Clean Harbors has also granted its underwriters a 30-day option to
purchase up to 375,000 additional shares.

Clean Harbors expects to receive net proceeds, after underwriting
discounts and expenses and assuming the underwriters' over-allotment
option is not exercised, of approximately $150.8 million. The Company
expects to use the net proceeds of the offering toward one or more of
the following: potential future acquisitions, repayment of debt and
working capital.

Goldman, Sachs & Co. is acting as the sole book-running manager of
the offering. Credit Suisse Securities (USA) LLC and Merrill Lynch &
Co. are acting as senior co-managers, and RBC Capital Markets
Corporation, Needham & Company, LLC and Wedbush Morgan Securities,
Inc. are acting as co-managers.

The shares are being offered only pursuant to the prospectus
supplement to the base prospectus included in a registration
statement, which was filed with the Securities and Exchange Commission
and became effective on April 17, 2008. Copies of the prospectus
supplement (and base prospectus) may be obtained by visiting the SEC's
website at www.sec.gov or by contacting Goldman, Sachs & Co., Attn:
Prospectus Dept., 85 Broad Street, New York, NY 10004, Fax:
212-902-9316 or email at prospectus-ny@ny.email.gs.com.

This release shall not constitute an offer to sell or the
solicitation of an offer to buy any of these securities, nor shall
there be any sale of these securities in any state in which such
offer, solicitation or sale would be unlawful prior to registration or
qualification under the securities laws of any such state.

About Clean Harbors, Inc.

Clean Harbors is North America's leading provider of environmental
and hazardous waste management services. Headquartered in Norwell,
Massachusetts, Clean Harbors has more than 100 locations strategically
positioned throughout North America in 36 U.S. states, six Canadian
provinces, Mexico and Puerto Rico.

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, and involve risks and
uncertainties. These forward-looking statements are generally
identifiable by use of the words "believes," "expects," "intends,"
"anticipates," "plans to," "estimates," "projects," or similar
expressions. These forward-looking statements are subject to certain
risks and uncertainties that could cause actual results to differ
materially from those reflected in these forward-looking statements.
Readers are cautioned not to place undue reliance on these
forward-looking statements, which reflect management's opinions only
as of the date hereof. The Company undertakes no obligation to revise
or publicly release the results of any revision to these
forward-looking statements other than through its various filings with
the Securities and Exchange Commission. Furthermore, all financial
information in this press release is based on preliminary data and is
subject to the final closing of the Company's books and records.

A variety of factors beyond the control of the Company may affect
the Company's performance, including, but not limited to:

-- The Company's ability to manage the significant environmental
liabilities that it assumed in connection with the CSD and
other acquisitions;

-- The availability and costs of liability insurance and
financial assurance required by governmental entities relating
to our facilities;

-- The effects of general economic conditions in the United
States, Canada and other territories and countries where the
Company does business;

-- The effect of economic forces and competition in specific
marketplaces where the Company competes;

-- The possible impact of new regulations or laws pertaining to
all activities of the Company's operations;

-- The outcome of litigation or threatened litigation or
regulatory actions;

-- The effect of commodity pricing on overall revenues and
profitability;

-- Possible fluctuations in quarterly or annual results or
adverse impacts on the Company's results caused by the
adoption of new accounting standards or interpretations or
regulatory rules and regulations;

-- The effect of weather conditions or other aspects of the
forces of nature on field or facility operations;

-- The effects of industry trends in the environmental services
and waste handling marketplace; and

-- The effects of conditions in the financial services industry
on the availability of capital and financing.

Any of the above factors and numerous others not listed nor
foreseen may adversely impact the Company's financial performance.
Additional information on the potential factors that could affect the
Company's actual results of operations is included in its filings with
the Securities and Exchange Commission, which may be viewed at
www.cleanharbors.com/investor_relations.

Clean Harbors, Inc.
James M. Rutledge, 781-792-5100
Executive Vice President and Chief Financial Officer
InvestorRelations@cleanharbors.com
or
Bill Geary, 781-792-5130
Executive Vice President and General Counsel
or
Sharon Merrill Associates, Inc.
Jim Buckley, 617-542-5300
Executive Vice President
clhb@investorrelations.com

Copyright Business Wire 2008