|
|
|
OIL SPILL BOOKS |
Metula SpillMetula SpillFirst Narrows, Strait of Magellan 08/09/74 Incident Summary On August 9, 1974, at 2220, the VLCC (Very Large Crude Carrier) Metula ran hard aground on Satellite Bank, at the western end of First Narrows in the Strait of Magellan near the southern tip of South America. The vessel was traveling from west to east at nearly fifteen knots and came to a stop in approximately 260 feet (the Metula was over one thousand feet long and ordinarily required three miles to stop). Oil immediately began pouring into the water from ruptured cargo and fuel tanks. Behavior of Oil Light Iranian crude oil has an API gravity of 33.4 and a pour point of -30 degrees F. Bunker C fuel oil is a heavy product with an API gravity that ranges from 7 to 14. The oil moved predominantly to the west into Bahia Felipe and Bahia Gregario, with lesser movement to the east into Bahia Posession. The oil was driven by currents as high as ten knots and winds from the northwest at thirty to fifty knots. Within the first three weeks, the wind forced the oil onto the northern shoreline of Tiera del Fuego. Oil deposited on the beach took on two different forms. A dark brown mousse with a five per cent water content plus sand, seaweed and other debris was deposited above the spring high-tide line and in the marshes and estuaries. A lighter mousse with a thirty per cent water in oil emulsion was deposited extensively in the intertidal zone. The lighter mousse coated the beaches from 18 to 55 yards wide and to a depth of 3 inches. Light mousse also covered the gravel and cobbles of the rocky intertidal area during low tide. At Punta Espora, the intertidal flats near the ferry were paved with a mixture of mousse, sand, gravel, organisms and other debris. The observed area was more heavily covered in the January 1975 survey than at the time of the incident. At sheltered tidal flats, as found at First Narrows, the thick asphalt-like covering persisted for over 12 years with no signs of significant weathering. In the heavily oiled salt marsh, nearly all the vegetation was still dead over five years later. Some of the less heavily oiled salt marshes showed signs of recovery after only five months. Major contamination was still visible on the third survey, in January 1976, nearly seventeen months after the grounding. During this survey, the intertidal zone at Punta Espora was described as a paved roadway 550 to 650 yards wide and 1.5 to 2.5 miles long, and ranging from 4 to 12 inches thick. The seaward 100 yards of the intertidal zone had abundant algae and mussels, and most of the hard pavement there had eroded away. Countermeasures and Mitigation The was no action taken to contain or disperse the oil that spilled from the Metula. Operations were hampered by rough weather, logistical difficulties and financial responsibility. For this reason, the Metula spill area became a natural laboratory for studying the long-term effects of oil on the environment. Consideration had been given to cleanup. Boom was expected to be ineffective due to the strong currents and tides. Chemical dispersants and the equipment to apply them were not available. They would have been difficult to use and possibly ineffective due to the weather and tidal conditions. It was estimated that 5,000 tons of dispersant chemicals would have been required to disperse the quantity of oil spilled from the Metula. Lack of cleanup equipment and personnel would have made an effective beach cleanup impossible. Much of the affected shoreline was inaccessible to heavy equipment, even if the equipment had been available. There was also considerable concern about the possible damage to the environment caused by cleanup with chemicals or mechanical equipment. Chilean authorities decided that cleanup of the beaches was not warranted, in view of other economic needs and the relative ecological importance of the area. It was felt that there was no way to have prevented the pollution of the beaches, and that the response effort was better spent on re-floating the vessel and preventing further spillage of oil. Four lightering operations were carried out to remove enough of the remaining cargo from the vessel to facilitate re-floating. All three of the USCG Air-Deliverable Anti-Pollution Transfer System (ADAPTS) lightering pumps were used during all phases of the offloading and ballasting. Following the lightering operations, air was pumped into sealed compartments. As the air was pumped in, the ADAPTS pumps continued to pump out ballast water in an effort to lighten and re-float the vessel. Two attempts were made, but the tugs were unable to pull it free of the rocks. On September 24, during a period of fifty knot winds, the Metula floated free and was pulled to a pre-selected anchorage approximately 13 miles from Punta Baxa. Offloading continued, despite periods of gale and hurricane force winds, until October 10. The USCG personnel and equipment departed the area on October 19. Other Special Interest Issues Marine birds were very heavily affected by the spill. Observations during a September 14 to 16 survey conducted between Punta Anegada and Punta Piedra (nearly fifty miles of impacted beach), found 581 dead birds. This number included 84 seagulls, 23 ducks, 66 penguins, and 408 cormorants. Estimates of bird mortality ran as high as 2,000. A penguin migration from the Atlantic Ocean to rookery islands in the Strait of Magellan was a primary concern to scientists at the time of the spill. A worst-case scenario involved migration of tens of thousands of penguins. When this migration did finally occur in mid-September, the leaking from the Metula was stabilized and most of the spilled oil had already beached on the shore or in the estuaries. USCG National Strike Force (NSF) personnel were sent to the site of the grounding at the request of the Chilean government. Ten people were on-scene to support and guide any cleanup measures that might be undertaken, and to assist with the salvage and lightering operations of the vessel. They arrived in Punta Arenas on August 27 with three Air-Deliverable Anti-Pollution Transfer System (ADAPTS) and their supporting gear. Personnel from the National Oceanic and Atmospheric Administration (NOAA) arrived at the site of the grounding five months after the incident, during January 1975, as part of a U.S. team that included representatives of the Environmental Protection Agency (EPA) and the USCG. The team studied the effects of the oil on the habitats and marine life that were impacted by the spill. References This content has been excerped from: Oil Spill Case Histories 1967-1991: Summaries of Significant U.S. and International Spills |
Copyright OilSpills.org 2004. All Rights Reserved. |