The on-scene assessment operations of the sunken World War II tanker S.S. Montebello are nearly complete off the coast of Cambria, Calif., and the unified command has determined that there is no substantial oil threat from the Montebello to California waters and shorelines. The only operation that remains is the collection of hull samples to help determine corrosion status.
Over the past 11 days, a unified command led by the Coast Guard and California Department of Fish and Game's Office of Spill Prevention and Response assessed cargo and fuel tanks, as well as collected ocean floor sediment samples, using an underwater remotely operated vehicle (ROV). The sediment and tank samples that were collected are being sent for further analysis.
"Our number one objective for this mission was to determine what threat, if any, the Montebello poses to the waters and shorelines of California," said Coast Guard Capt. Roger Laferriere. "After careful evaluation of the data, we have concluded with a high level of confidence that there is no oil threat from the S.S. Montebello."
"This is a new era of prevention," said DFG OSPR Capt. Chris Graff. "This has been a cooperative partnership using cutting-edge technology and surgical precision. The procedures and techniques used could help conduct threat assessments on other sunken vessels."
NOAA scientists conducted computer trajectory models based on a number of hypothetical release scenarios.
"Given the data discovered and records available, a long-term release model seems most reasonable," said NOAA Scientific Support Coordinator Jordan Stout. "Such model indicates that most of the oil remained offshore and headed south, some would have evaporated within the first few days, and the remainder may have washed ashore but may have been so widely scattered it went unnoticed. There are a number of unknowns associated with this release; therefore, we will probably never know exactly what happened to the oil."
The final report on the Montebello assessment operations is expected to be released sometime next spring.
The assessment operation was funded entirely by the Oil Spill Liability Trust Fund, a tax paid by the oil industry and not the general taxpayer. Approximately $5 million was budgeted for the operation.
ROV operations on the Montebello included:
- An initial vessel assessment that resulted in the collection of video and data that aided in the assessment of the overall condition of the ship.
- Ultrasonic hull thickness gauging indicates the hull is structurally sound.
- Neutron backscatter analyses, a non-destructive technology that helps determine the probability of oil within the tank, was performed and helped prioritize tank sample procedures.
- Sediment samples have been collected from the area surrounding the vessel and will undergo lab analysis, however, there was no visual evidence of oil contamination.
- Tank samples have been drawn and visual inspection indicates there is no quantifiable amount of oil onboard.
- Hull samples will be collected for metallurgic testing which will help determine corrosion status.