Aerial application of herding agents to advance in-situ burning for oil spill response in the Arctic: A pilot study

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In-situ burning (ISB) aided by herding agents is a promising tool for oil spill response in Arctic waters. An advantageous aspect of the herder mediated ISB approach is that the application of herders as well as the subsequent ignition of the slick could potentially be carried out from aerial platforms. This could obviate the need for personnel to conduct operations on the surface near the burn, as well as reduce the response time required to mobilize the spill response equipment, especially in difficult Arctic conditions. In the last decade, several laboratory and field-scale tests have been conducted to prove the efficacy of herding agent mediated ISB operations, sometimes achieving burn efficiencies >90%. However, there have been no reports of aerial herder application followed by ignition. The objectives of this work were to evaluate a proof-of-concept level application of aerial herders and igniters for ISB operations in the Arctic, and to investigate the associated operational and technical challenges. This paper presents results from a series of field experiments performed in a custom-built test basin 50km northeast of Fairbanks, Alaska, in April 2015. A helicopter was employed to first apply herding agents (Siltech OP-40 or ThickSlick 6535) to Alaska North Slope crude oil slicks in simulated drift ice conditions, and then ignite the herded slicks using a heli-torch. Burn efficiency (BE) for the confined field scale in-situ burn tests ranged from 59% to 94% using the gravimetric approach and 73% to 84% using the conservative aerial imagery approaches to evaluate the herder action. The moderately high BE values observed in the field-scale light ice-cover (~10%) conditions, establish the effectiveness and promise of aerial application of herders to assist ISB in the Arctic. This is a first account of successful aerial application of herders for ISB in the Arctic or elsewhere, and furthers the development of better tools for oil spill response in Arctic waters and beyond.