Clamshell dredge No. 54 removes rock fragments from areas where blasting operations have already been completed near Marcus Hook, PA (Sunoco refinery in background). The U.S. Army Corps of Engineers and its contractor Great Lakes Dredge & Dock Company are conducting rock blasting operations on the Delaware River. Work is a part of a project to deepen the federal channel of the river to provide for more efficient maritime transport of cargo.