NOAA's Response and Restoration Blog

An inside look at the science of cleaning up and fixing the mess of marine pollution

Solving the Oily Mystery of the Wrecked S/S Montebello

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This is a post by Jordan Stout, the Office of Response and Restoration’s Scientific Support Coordinator based in Alameda, Calif.

Underwater image of the Montebello wreck.

An underwater photo of fishing net draping the wreck of the S/S Montebello, taken by the remotely operated vehicle (ROV). Credit: NOAA/Robert Schwemmer.

In a refreshing change for those of us who deal with oil spills, the mystery of the S/S Montebello, a U.S. oil tanker sunk only two weeks after Pearl Harbor, has finally been solved and it’s good news: There is no sign of the more than 3 million gallons of crude oil on board the ship when it went down nearly 70 years ago.

Given the data discovered and records available, a long-term model says it’s likely that most of the oil remained offshore and headed south, while some would have evaporated within the first few days. The remainder may have washed ashore but may have been so widely scattered it went unnoticed. We will probably never know exactly what happened to the oil.

Submersible dives indicated the Japanese torpedo that sunk the Montebello missed the cargo tanks where the oil was held. Originally, some people speculated that the oil might have leaked out the vent pipes. Others thought the oil had solidified in the cold bottom waters off the coast of San Pedro, Calif., and was still inside the ship.

But with limited information, the best we could do was make educated guesses about how and when an oil spill might occur from this ship. What we really needed was to look inside the tanks for oil and, if we found any, assess the wreck’s overall condition. Even with the cargo tanks in relatively good condition, the Montebello was degrading over time, and any oil still on board could pose a threat of an uncontrolled oil release, which can be an expensive, difficult, and potentially hazardous endeavor.

In recent years, there has been a growing concern about potential pollution from the thousands of shipwrecks in U.S. waters. A number of wrecks in the Pacific Basin have undergone some kind of focused assessment and oil removal, which helped us with these operations.

The S/S Montebello was different, however, because it was not actively leaking oil at the time, and the assessment would be performed entirely by remotely operated vehicles (ROVs). In addition, we used some innovative and very specialized technologies, including:

  • ultrasonic thickness gauges (to figure out how thick the ship’s hull is).
  • neutron backscatter detectors (to determine the likelihood of oil being in the tanks, without damaging them).
  • a specialized ROV-mounted drill bit that drilled a small hole in the ship, grabbed an oil sample, and then sealed the hole when the tool was extracted (a tool specially built for this project).

Carefully and methodically applying these tools gave us convincing answers while limiting the number of holes created in the ship.

Of course, the more we looked for oil in the S/S Montebello, the less we found. And, in truth, I found that to be a bit anti-climactic. Even so, a long-standing mystery has finally been solved, and I’m proud of our efforts.

Jordan Stout

Jordan Stout.

Jordan Stout currently serves as the NOAA Scientific Support Coordinator in California where he provides scientific and technical support to the U.S. Coast Guard and Environmental Protection Agency in preparing for and responding to oil spills and hazardous material releases.  He has been involved in supporting many significant incidents and responses in California and throughout the nation and was on-scene for the S/S Montebello assessment operation.

Author: Office of Response and Restoration

The National Ocean Service's Office of Response and Restoration (OR&R) provides scientific solutions for marine pollution. A part of the National Oceanic and Atmospheric Administration (NOAA), OR&R is a center of expertise in preparing for, evaluating, and responding to threats to coastal environments. These threats could be oil and chemical spills, releases from hazardous waste sites, or marine debris.

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