Subsurface Oil and Waves in The Coastal Zone

Abstract

Over the last decade, there have been more and more oil spill responses effected by subsurface waves in the coastal zone. These have ranged from oil leaking from sunken ships to heavy oils that have sunk to the bottom. A primary example is the DBL 152 incident on the Gulf of Mexico coast in November, 2006. The incident resulted in approximately 70,000 barrels of Slurry Oil (API 4) being released and sinking to the bottom. Waves played a significant role in the mobilization of the oil on the bottom, in addition to effecting sediment loading in the subsurface, often restricting visibility and making ROV operations difficult. Waves can also play a major role disturbing sunken ships, and evidenced by the SS Jacob Luckenbach, sunken off San Francisco during WWII. The ship was a source of occasional incidents of oiled birds washing ashore after certain winter storms. The oil on the ship was removed as part of a major remediation effort in the summer of 2002.The oil spill response community will be more effective, particularly with subsurface oils, with a better understanding of the role of waves on the mobilization of sediment and other deposited substances (such as subsurface oil). This paper provides an overview of wave mechanics and the implications for subsurface oil movement and spill response activities, using examples from the DBL 152, SS Jacob Luckenbach, and other recent incidents. Shortcomings of current understanding will be highlighted, with suggestions for future research offered.