The metal test samples will be removed at different times and studied to determine their corrosion rate, which will then be used to determine how long until the hull of the USS Arizona has before it collapses.
“This is the first time that scientific results will be made from a test done on the Arizona by cadets,” said Grant. “Though we are not actually testing the Arizona, the racks are placed on the hull giving us the same results as the actual ship.”
The USS Arizona remains submerged where Japanese forces sank it on December 7, 1941, with the loss of 1,177 crew members. It is estimated that 900 crewmen remain on the ship.
Because the ship was so severely damaged, it was considered a total loss and the Navy did not attempt a salvage effort. As the wreck’s location was not a navigation hazard, the ship was allowed to remain where it sank and was declared a burial at sea. The Arizona is now considered an active American military cemetery.
“While conducting science, it is important to put our work in context,” said Capt. Richard Sanders, the cadets’ research advisor. “The USS Arizona is the final resting place for almost all of the sailors and marines who lost their lives aboard the ship during the attack in 1941. We carry out our tasks with a respectful awareness.”
According to the National Park Service, an estimated half-million gallons of fuel oil remain aboard the ship, either in original bunkers or trapped beneath overheads of numerous undamaged compartments.
Oil leaking from the sunken battleship can still be seen rising from the wreckage to the water’s surface. This oil is sometimes referred to as “the tears of the Arizona” or “black tears.”
Metal coupons hang from a PVC pipe rack before being placed on the USS Arizona in Pearl Harbor, Hawaii, by Coast Guard Academy cadets and 24 hours after being submerged in the water. On the submerged rack there are already signs of rust and marine growth. Courtesy Coast Guard Academy First Class Cadet Marshall Grant / USCG
Every day the Arizona is estimated to leak two liters of black tears into the water. It is unknown where the oil is leaking. The ship sits in 26 feet of water and another 30 feet of mud, so it is impossible for scientists to explore the lower part of the ship.
Since 1998, the National Park Service’s Submerged Resources Center and Valor in the Pacific National Monument, formerly USS Arizona Memorial, have been conducting research directed at understanding the nature and rate of natural processes affecting deterioration of the Arizona, as well as monitoring hull condition and oil release rates.
The USS Arizona Preservation Project was designed to be multi-year, interdisciplinary and cumulative project with a primary focus on collecting requisite data for understanding the complex corrosion processes affecting Arizona’s hull, both internally and externally, and modeling and predicting the nature and rate of structural changes to aid in developing reasonable and effectual management decisions, including relating to oil release.
“The initial corrosion reaches a certain point and then it stabilizes, said Seymour. “We want to know how long it takes to get to that stabilization and to see the overall life span of the Arizona.”
The racks placed and designed by the cadets are made of PVC pipe and hold several metal testing samples called coupons. The racks were placed at the bow, under the memorial and on both sides of the ship. The coupons will be removed from the racks at specific times and then sent to the Coast Guard Academy where they will be cleaned and tested for mass loss.
Grant from Acton, Massachusetts, who has been working on this project since his freshman year, acted as administrative point of contact for the cadets, which includes the operations, planning, and logistics of fieldwork. Grant also serves as the lead cadet on laboratory work, data analysis and presentation of results.
“It was such an honor to be part of this project,” said Grant. “This project is special because it involves science but also carries an emotional weight.”
Before placing the racks, the cadets meet up with Brett Seymour of the National Park Service Submerged Resources Center, who gave them information about the USS Arizona and diving on it.
“Seymour was amazing,” said Grant. “His knowledge of the ship is extremely instrumental for this project.”
To learn more about the sunken ship, Seymour showed the cadets drawings, models and photos. Then they took a dive tour to familiarize themselves with the ship and see the oil collecting on the ceilings of the ship.
Once the cadets had a grasp of the ship and its hull, they prepared to place the racks. The metal samples began showing the effects of the water within 24 hours of being placed on the ship.
“We dove down the next day to check on the racks,” said Grant. “The once shiny metal samples were already turning brown and had a layer of growth on them.”
The coupons will be removed and tested at several different weeks, six months, one year, two years and three years.
“We hope to discover a pattern of mass loss in the coupons which can then be used to determine the long term corrosion pattern of sunken ships in the same type of water,” said Grant. “The project is not just about the long term preservation of the USS Arizona but of all shipwrecks with potential pollution.
The USS Arizona is not the only wreck in U.S. waters that has the potential for a pollution emergency. The National Oceanic and Atmospheric Administration has identified 573 shipwrecks as potential polluters, narrowed down to 87 upon further assessment with 36 of them identified as worst-case discharge. As these shipwrecks continue to sit in water they continue to corrode, increasing the likelihood of a leak.
“This experience solidified the connections between science, leadership and training,” said First Class Cadet Alicen Re. “We worked so closely with people outside of the Coast Guard and learned so much. Sitting in the room with these top scientists, it really hit home. Because of the Academy, I was able to have this incredible opportunity.”
The National Park Service estimates that the USS Arizona has between 100 to 150 years before the hull gives away, but this new study can help pinpoint the exact timing.
This is not the first time that students at the Academy have worked on the USS Arizona and its corrosion rate. In 2015, cadets at the Academy were able to study samples from the Arizona. They used the samples to investigate how rivets and hull plating contributes to galvanic corrosion by determining which of those components corrode more quickly and lead to vessels collapsing.
In 2016, cadets participated in a symposium in Hawaii focused on the USS Arizona. They were presenting their findings on the corrosion processes and extend knowledge gained from the Arizona to legacy vessels and potentially polluting shipwrecks.