In September 1946, the WWII-era U.S. Army Transport ship General M. G. Zalinski sank after running aground some 100 kilometers south of Prince Rupert, Canada while en route from Washington to Alaska. All of her crew managed to escape, but the ship sank with all cargo, including bombs and ammunition, and an estimated 700 tons of fuel oil still aboard.
Nearly 60 years later, mysterious oil slicks began appearing on the surface and along shorelines of the Grenville Channel in British Columbia’s Inside Passage, leading to the discovery of the Zalinski wresting upside down, on a steep underwater cliff in some 27 meters of water.
In the years that followed, it was determined that the deteriorating condition of the vessel posed an imminent threat of a large release of oil, a looming environmental disaster.
After a tender for the fuel oil removal, the Canadian government contracted Mammoet Salvage and its strategic partner, Global Diving & Salvage from Seattle, for job. Mammoet was to use a method known as “hot tapping” to extract the oil, a well-known and frequently used method of removing oil from the tanks of stricken vessels. The method involved drilling a hole through the hull and into the tank, then heating the oil to lower its viscosity. With the oil more freely flowing, it could then to be pumped from the tanks to the surface and stored onboard a vessel. At the same time water was injected into the tank to equalize pressure and maintain the tanks integrity.
The operations were successfully completed in March 2014 and the Zalinski no longer poses a threat to the environment.
Below is the full story of the project as told by the salvors: