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USGS Researchers Collaborate with National Park Service Archeologists to Better Predict the Life Expectancy of the USS Arizona
As many visitors (more than 1,000 per day) have noticed, black fuel oil leaks from the hull at a rate of about a quart per day, causing a shimmer of colors on the surface waters. Over the past 6 decades, the hull has undergone substantial deterioration in the harbor's corrosive environment; bulkheads have collapsed, and many of the ship's overheads are corroded and weakened.
More than half a million gallons of fuel oil still trapped in the fractured hull poses a serious environmental risk, with the potential for much of the oil being released into the harbor when the Arizona's fuel bunkers finally give way. This threat led to a major initiative started in 2000 by the NPS to document the condition of the USS Arizona in order to answer some basic questions: What is happening to the wreck? How long will it remain intact?
Since 2000, archeologists from the NPS' Submerged Resources Center (SRC) have conducted several surveys of the USS Arizona. In addition, engineers from the University of Nebraska have conducted detailed studies of the corrosion rate of the hull's metal and the present structural integrity of the ship. In fall 2002, Mike Field (USGS, Santa Cruz, CA) was asked by NPS-SRC archeologists Larry Murphy and Matt Russell for advice on deploying oceanographic instruments on the Arizona to make measurements of the seawater environment around the ship. Mike brought in Curt Storlazzi (USGS, Santa Cruz, CA) to design an experiment setup, instrument mounts, sampling routines, and deployment and recovery protocols for Marshall Owens, the USS Arizona Memorial's curator.
In early November, Kevin O'Toole and Walt Olson of the USGS' Marine Facility in Redwood City, CA, built the mounts for a wave/tide/current-meter package and a separate multisensor to measure temperature, salinity, dissolved oxygen, pH, and reduction potential. On November 19 and 20, Mike and Curt worked with NPS archeologists and Memorial staff to build and program the instrument packages, and they trained NPS staff in instrument-recovery-and-deployment protocols.
After the successful deployment of the wave/tide/current-meter package, Matt and Marshall gave an hour-long underwater reconnaissance tour of the USS Arizona to Mike and Curt. They were shown bomb damage, artifacts, exposed intact teak deck, and the number-one turret with its three 14-inch guns. Interestingly, the turret was thought to have been removed by the Navy during salvage operations in 1942 but was found intact on the hull by NPS archeologists in 1983.
Every 2 months for 1 year, the NPS staff will send the instrument data to Curt, who will analyze the data to gain a better understanding of the harbor's environment and what controls it. This information, in turn, will be used to more accurately predict the life expectancy of the USS Arizona's hull and fuel bunkers. USGS researchers, along with NPS staff, hope to establish a cooperative program to continue this scientific effort on behalf of one of the Nation's most hallowed grounds and a potent symbol of our history.
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