The chief engineer of an oil tanker that transports petroleum products to and from various ports in the United States and abroad pleaded guilty today to submitting false documents to the U.S. Coast Guard in an effort to cover up the illegal dumping of thousands of gallons of waste oil and sludge at sea, U.S. Attorney Christopher J. Christie announced. The captain of the vessel also pleaded guilty before U.S. District Judge Katharine S. Hayden to conspiracy in connection with his effort to conceal evidence and solicit false statements from a lower-level engineer during the Coast Guard boarding of the ship in the Port of Carteret on Sept. 10, Christie said.