Aerial Application of Herding Agents can Enhance In-Situ Burning in Partial Ice Cover

Abstract

ABSTRACT 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 challenging Arctic conditions. In the last decade, several laboratory and field-scale tests have been conducted to prove the efficacy of herder-assisted ISB operations, sometimes achieving burn efficiencies greater than 90 %. However, there have been no field tests of aerial herder application followed by ignition. This paper presents results from a series of field experiments performed in a custom-built test basin 50 km 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. Two of five test burns yielded measurable outcomes, resulting in 70% - 85% removal of the test oil as it was drifting freely. Three of five test burns did not yield reliably measurable results, as wind action at the site prevented an accurate measurement of free-drifting burn efficiency. An unmanned aircraft, carrying prototypical payloads for herder spraying and in situ burn ignition was also tested. This is the first time successful aerial application of herders for ISB in the Arctic or elsewhere has been accomplished, and furthers the development of better tools for oil spill response in Arctic waters and beyond.