Recovery of the Irving Whale oil barge: Overflights with the laser environmental airborne fluorosensor

In the summer of 1996 the oil barge, Irving Whale, was successfully raised from the depths of the St Lawrence River with the majority of its cargo of bunker C fuel oil intact. As part of the recovery effort, the Emergencies Science Division of Environment Canada performed airborne remote sensing flights over the site of the barge prior to, during and following the lift procedure. The primary sensor employed during these remote sensing flights was the laser environmental airborne fluorosensor (LEAF). Additional equipment on board Environment Canada's DC-3 aircraft included an RC-10 colour mapping camera and two down-looking video cameras. In the days leading up to the lifting of the Irving Whale, the LEAF system detected bunker C fuel oil on the surface of the gulf in close proximity to the location of the sunken barge. This oil was believed to have been dislodged from beneath structures on the top of the barge during inspections, welding and other preparations in advance of the lift. On the actual day of the lift, 30 July, greatly increased amounts of bunker fuel were detected. During each overflight, the real-time LEAF system produced timely, concise map-based oil contamination information in hard-copy form. The locations of the visibly thick and recoverable oil were radioed to spill response personnel on the surface and promptly recovered by booming and skimming operations. In addition, the LEAF system found extremely thin, sub-sheen levels of oil over the majority of the southern Gulf of St Lawrence on the day of the lift. The extent of this coverage was greatly reduced the following day (presumably due to further spreading) and essentially eliminated by 1 August. The LEAF system on the DC-3 continued to monitor the Irving Whale as it was transported to Halifax, Nova Scotia on the deck of the submersible vessel Boabarge 10. During transit no oil which could be attributed to the Irving Whale was detected, apart from a small residual amount at the lift site.