Great Lakes Dredge & Dock Corporation Announces $100 Million Secondary Offering.

OAK BROOK, Ill. -- Great Lakes Dredge & Dock Corporation (NASDAQ: GLDD and GLDDW) ("Great Lakes" or the "Company") today announced a $100 million secondary offering of shares of its common stock by certain selling stockholders, pursuant to a registration statement filed with the Securities and Exchange Commission. The selling stockholders include Madison Dearborn Capital Partners IV, L.P. Great Lakes will not receive any proceeds from the sale of the shares but will pay the expenses of the offering.

A registration statement relating to the securities described above has been filed with the Securities and Exchange Commission but has not yet become effective. These securities may not be sold nor may offers to buy be accepted prior to the time the registration statement becomes effective. This press release shall not constitute an offer to sell or a solicitation of an offer to buy, nor shall there be a sale of these securities in any state or other jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

The offering is being made through an underwriting syndicate led by Banc of America Securities LLC and Lehman Brothers Inc. as joint book-running managers for the offering. A copy of the prospectus relating to the shares, when available, may be obtained from Banc of America Securities LLC, Attention: Prospectus Department, Markets Operations, 100 West 33rd Street, New York, NY 10001, or by email to [e-mail] or from Lehman Brothers Inc., c/o Broadridge, Integrated Distribution Services, 1155 Long Island Avenue, Edgewood, NY 11717, or by email at [e-mail] or by fax at [phone].

About Great Lakes Dredge & Dock Corporation

Great Lakes is the largest provider of dredging services in the United States and the only U.S. dredging company with significant international operations, averaging 18% of its dredging revenues over the last three years. Great Lakes also owns an 85% interest in North American Site Developers, Inc., one of the largest U.S. providers of commercial and industrial demolition services. Additionally, the Company owns a 50% interest in a marine sand mining operation in New Jersey which supplies sand and aggregate used for road and building construction.

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