Great Lakes Dredge & Dock Corporation declare a quarterly cash dividend on its common stock. The Board approved a $0.021 per share cash dividend, to be paid on September 14, 2012 to the holders of record of common stock of the Company at the close of business on September 7, 2012. Great Lakes Dredge & Dock Corporation is the largest provider of dredging services in the United States and the only U.S. dredging company with significant international operations. The Company is also one of the largest U.S. providers of commercial and industrial demolition services primarily in the Northeast. The Company owns a 50% interest in a marine sand…