Controlled Burning of Crude Oil on Water Following the Grounding Of the Exxon Valdez
ABSTRACT During the evening of the second day following the Exxon Valdez oil spill, an estimated 15,000 to 30,000 gallons (57,000 to 114,000 L) of North Slope crude oil were eliminated using in-situ combustion techniques. The oil was collected with the 3M Company's Fire Boom, towed in a U-shaped configuration behind two fishing boats. Working with 500-foot (152-m) tow lines, a 450-foot (137-m) boom was moved at about one-half to one knot (0.26 to 0.52 m/s) through slightly emulsified oil patches downwind of the spill. Once oil had filled the downstream portion of the U-shaped boom and the boats were clear of any surrounding slicks, a gelled-fuel igniter was released from one of the tow boats. Shortly after ignition, flames gradually spread out over the entire area of the contained oil. As flames reached 200 to 300 feet (61 to 91 m) into the air, the area of the contained oil layer (and therefore the size and intensity of the fire) could be controlled by adjusting the speed of the vessels. The total burn time was approximately 75 minutes; however, the intense part of the burn lasted for about 45 minutes. The original volume of oil, likely between 15,000 and 30,000 gallons, was reduced to approximately 300 gallons (1,136 L) of stiff, taffy-like burn residue that could be picked up easily upon completion of the burn. The controlled elimination of crude oil therefore resulted in an estimated 98 percent or better efficiency of burn.