APPENDIX A: IN SITU BURNING
Appendix A
1.0 INTRODUCTION
The use of in situ burning (ISB) as a spill response technique is not new, having been researched and used for a variety of oil spills since the late 1960s. In general, the technique has proved effective for oil spills in ice conditions and has been used successfully in the past to remove oil spills in ice-covered waters resulting from pipeline, storage tank, and ship accidents in Alaska, Canada and Scandinavia.
Although there have been numerous incidents of vessel oil spills that inadvertently caught fire, the intentional ignition of oil slicks on open water has only been seriously considered since the development of fire-resistant oil containment boom beginning in the early 1980s. The development of these booms offered the possibility of conducting controlled burns in open water conditions.
In situ burning of thick, fresh slicks can be initiated very quickly by igniting the oil with devices as simple as an oil-soaked sorbent pad. In situ burning can remove oil from the water surface very efficiently and at very high rates. Removal efficiencies for thick slicks can easily exceed 90%. Removal rates of 13,000 bbl/h (2000 m3/h) can be achieved with a fire area of only about 10,000 m2 or a circle of about 33 ft (100 m) in diameter. The use of towed fire containment boom to capture, thicken and isolate a portion of a spill, followed by ignition, is far less complex than the operations involved in mechanical recovery, transfer, storage, treatment and disposal. If the small quantities of residue from an efficient burn require collection, the viscous, taffy-like material can be collected and stored for further treatment and disposal. There is a limited window of opportunity for using in situ burning with the presently available technology. This window is defined by the time it takes the oil slick to emulsify; once an oil emulsifies, and the water content exceeds about 25%, many slicks are unignitable. The application of emulsion breakers can aid in the ignition of some slicks.
Despite the strong incentives for considering in situ burning as a primary countermeasure method, there remains considerable resistance to the approach. ISB has been seldom used during actual responses due to misinformation, lack of resources, incomplete plans, and health and safety concerns. There are two major concerns: first, the fear of causing secondary fires that threaten human life, property and natural resources; and, second, the potential environmental and human-health effects of the by-products of burning, primarily the smoke.
The objective of this Appendix is to review the science, technology, operational capabilities and limitations, and ecological consequences of in situ burning as a countermeasure for oil spills on water. The main focus of this section is on marine oil spills in open water conditions. Much of the content of this Appendix is adapted from: an in-depth review of in situ burning produced for the Marine Spill Response Corporation (MSRC) [2] summarized and updated for IUPAC [3], and the USCG In-situ Burn Operations Manual [4]. Interested readers are encouraged to refer to the original reports for fully referenced details of the summary presented here. The MSRC report is available from the American Petroleum Institute in Washington, DC and the USCG Manual is available from the USCG R&D Center in Groton, CT. Both documents are contained on an excellent resource CD produced by NIST for MMS that contains a large number of the key references and contingency plans for in-situ burning [5]. Finally, an update of the MSRC report focusing on the use of in-situ burning in Arctic conditions is available in a major report funded by the International Association of Oil & Gas Producers (OGP) [6].
(Eighteen pages of text and references)
