The Mega Borg Incident: A Comparison of Response, Mitigation, and Impact

Abstract

ABSTRACT On June 6, 1990 the M/V Mega Borg lost approximately 4.6 million gallons of light Angolan crude oil after experiencing onboard explosions. The ship was located 57 miles offshore of Galveston, Texas and contained a cargo of 41 million gallons of crude oil. The impact on the Texas coast and continental shelf was minimized by the small amount of oil escaping incineration and evaporation, removal of oil by skimmers, the weather conditions, and the open ocean location of the spill. Contamination of the upper ocean was restricted to areas associated with slicks and the benthos appeared to be uncontaminated. Dispersants effectively broke-up slicks in a test area and increased oil in the water column by as much as ten-fold. No M/V Mega Borg oil was detected on Texas beaches that were monitored. INTROPUCTION Late on June 9, 1990 the supertanker M/V Mega Borg was rocked by explosions 57 miles offshore of Galveston, Texas. The accident ultimately released more than 4 million gallons of crude oil and raised the spectre of a major environmental disaster. The response to this oil spill included fire containment; skimmer operations; the application of dispersants; and a coordinated collection of sediment, water, and slick samples to determine the environmental fate of the spilled oil. The initial results of these studies are reported here. THE ACCIDENT The M/V Mega Borg contained -41 million gallons of a light crude oil from Angola. During the process of off-loading of oil to a smaller tanker; i.e., "lightering"; an explosion occurred. The violent fire that erupted was fueled by the oil and gas spewing from ruptured tanks. Estimates are that -4.6 million gallons of the cargo were lost. In the days immediatelyfollowing the accident skimming activities recovered more than 100,000 gallons of crude oil. The amount of material available to form slicks was limited by the intense fires which consumed a major portion of the leaking oil. Evaporative loss of liquids and gases that escaped initial incineration was aided by the warm temperatures and persistent sea breezes. As the fire was brought under control the thickness and area covered by the oil slick rapidly increased and spread in a north, northwesterly direction. Estimates suggest that the slick represented -40,000 gallons of crude oil. The remainder of the lost cargo is presumed to have been consumed by fire and evaporation or contained by skimming activities. METHOPS - COLLECTION AND ANALYSIS OF WATER. SEDIMENTS, SLICKS AND ORGANISMS On June 11, 1990 a comprehensive sampling of water, sediments, and slickswas initiated. The sampling was designed to document the level of contamination, determine the fate of the spilled oil and evaluate various spill mitigation techniques. Samples were collected at 1/4, 1/2, 1, 2, and/or 4 miles from the ship along transects to the north, east, south and west of the M/V Mega Borg. Samples of water, sediments, and slicks were also collected in support of field testing of dispersants. Water samples were collected at 1, 3, 5, and/or 9 meters. Thirty liter Go-Flo samplers minimized contamination of water samples with surface slicks.