Exhibit 23.4

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the inclusion by reference in Registration Statement No. 333-153207 on Form S-3 and Registration Statement Nos. 333-150067 and 333-185350 on Form S-8 of our report dated March 27, 2015, relating to the consolidated financial statements of Amboy Aggregates Joint Venture and Subsidiaries and Lower Main Street Development, LLC (A Limited Liability Company), as of December 31, 2014 and the related consolidated statements of income and partners’ capital and cash flows for the years then ended, which appear in Great Lakes Dredge & Dock Corporation’s Annual Report on Form 10-K for the year ended December 31, 2015 as filed with the Securities and Exchange Commission on February 29, 2016. Our report contains an explanatory paragraph regarding the consolidated financial statements as of December 31, 2013 and for the years ending December 31, 2013 and 2012 were not subjected to audit, review, or compilation procedures and, accordingly, we do not express an opinion, a conclusion, nor provide any other assurance on such statements.

WithumSmith+Brown, PC

New Brunswick, New Jersey

February 25, 2016