BASELINE ENVIRONMENTAL DATA COLLECTION

Dr. Mike Field and Dr. Curt Storlazzi from the US Geological Survey’s (USGS) Pacific Science Center are continuing their collaboration with NPS-SRC and USAR researchers to analyze data from oceanographic and waterquality monitoring instruments placed on and near Arizona. NPS researchers and USGS scientists calibrated and deployed a SonTek wave height/current meter and a YSI multiparameter probe on Arizona in November 2002. These instruments have internal memory and batteries and can be left in situ for up to 60 days, recording data multiple times an hour. The instruments are retrieved and downloaded, then recalibrated and deployed every 60 days by USAR staff. The data are sent to the SRC in Santa Fe, New Mexico, and the USGS in Santa Cruz, California, for compilation and on-going analysis. These instruments continue to collect baseline data including wave and current patterns around the vessel, and basic environmental parameters, such as pH, temperature, salinity, dissolved oxygen, oxygen reduction potential and conductivity. The goal is at least a two-year database to discern environmental variable patterns within Pearl Harbor.

The SonTek instrument was left in place approximately 25 m off Arizona’s port bow for a one-year period, from November 21, 2002 to November 20, 2003 (Figure 6). On November 20, 2003, NPS staff relocated the instrument to 25 m off Arizona’s starboard bow, where it will collect comparative data for another year. The YSI instrument was deployed on January 30, 2003 on Arizona’s main deck, amidships, just aft of the Memorial (Figure 7). It has so far collected data for a one-year period, with the exception of four months during summer 2003 due to equipment malfunction. This instrument will be left in its current location at least through summer 2004 to make up for lost data. Data from both instruments will then be synthesized by USGS and NPS scientists to determine potential effect environmental variables have on Arizona’s corrosion rates.

Figure 6. SonTek Triton current/wave meter off Arizona’s port bow.

Figure 7. NPS researcher recovering YSI multi-parameter sonde.

FINITE ELEMENT MODEL (FEM) DEVELOPMENT

The NPS-SRC and USAR are collaborating with Dr. Tim Foecke and Dr. Li Ma at NIST to develop a Finite Element Model (FEM) of Arizona to characterize hull deterioration. A FEM allows manipulation of multiple variables, such as corrosion rate and hull thickness, to  analyze loads and stresses on hull structure for prediction of probable collapse rate, nature and sequence and consequent impact on structures containing fuel oil. The FEM provides a fundamental tool to evaluate consequences of proposed management alternatives involving structural intervention or preservation strategies. Initial FEM development is focusing on modeling the Arizona hull structure in its as-built original state for a 60-ft. cross-section, amidships from frame 75 to 90 (Figure 8). This preliminary model is a necessary step to refining and testing methodologies for development of the overall model required for predicting current structural strength and, when combined with corrosion rates and other variables, will provide predictability required for evaluating timing, necessity and long-range consequences of management actions.

Figure 8. 60-foot midships cross-section of USS Arizona modelled for Finite Element Analysis.

The next development stage will focus on incorporating structural effects of the blast and fire that sank the vessel. The final stage of FEM development will incorporate external and internal corrosion and thickness measurements. Collection of additional data and completion of this model will provide the foundation for determining most effective management alternatives, including fuel removal, containment or intervention in natural processes affecting the hull and the time scale for continued structural alterations that may require corrective action.

This work has been conducted by NIST over the course of FY02 and FY03 and will continue in FY04, as funding allows. FEM development requires significant and on-going interaction between NIST and NPS-SRC and a dynamic relationship between the two agencies. Analytical avenues evolve as additional data are collected and as the work is refined. This is pioneering research, and there is currently no standardized approach or protocol. NIST and NPS-SRC are working collaboratively to develop an integrated, multidisciplinary approach to long-term preservation research and ensure that on-going research, analysis and results complement other aspects of this project, which may require testing and revising engineering analysis techniques. Much refinement and many changes will have to be made to standard engineering practices for application to USS Arizona. There is currently no standardized methodology for addressing problems of the nature represented in this research.

The SRC partnership with NIST represents a significant cost savings to the current project because NIST is providing matching funds in the form of laboratory analyses, supervisory personnel, equipment, administrative support and infrastructure, all of which would have otherwise been levied against available Legacy funds. A senior metallurgist at NIST is supervising the analytical work conducted under this agreement, which will be completed using their computers, software and other equipment. The senior NIST researcher draws from experience with other historic vessels including Titanic and with structural failure of steel, as with the World Trade Center structural analysis. In addition, NIST will perform necessary metallurgical and metallographic sample analyses and consulting beyond the scope of this agreement with no additional charge to the project. To develop and refine such a protocol as required for historical vessels could be prohibitively expensive if it had to incorporate specific contract changes with a private firm charging hourly rates for engineers and equipment access. The success of this research endeavor solidly rests on the on-going collaboration between NIST and NPS-SRC.

OIL AND MICROBIOLOGICAL ANALYSIS

The NPS-SRC and USAR are collecting oil, sediment, water and concretion samples from Arizona for analysis by Dr. Pam Morris at the Medical University of South Carolina (MUSC) in support of on-going research at the site. MUSC scientists are currently developing innovative research that examines the role of microorganisms in fuel oil degradation and the aerobic biodegradation potential of microorganisms associated with the battleship’s hull. In addition, collaborative research is focusing on using environmental degradation of oil trapped within different areas of Arizona’s hull to determine relative dating of each oil cache through determining the length of time each oil release has been in contact with seawater. This approach should provide inferential indicators about the state of deterioration and structural changes of oil bunkers that are presently inaccessible.

MUSC researchers are analyzing oil samples using mass spectrometer biomarkers, gas chromatograph analyses and other methods (Figure 9). Results of analyses may differentiate individual oil bunkers, as well as differentiate age of oil (relative to sea water exposure) in cabin overheads and being released from various locations around the battleship, which has important implications for structural analysis. They are also analyzing environmental samples (water, sediment and concretion) to identify and describe and the nature of microbiological communities present and characterize their role in the overall corrosion process affecting Arizona’s hull and structural integrity and develop predictions about long-term changes in the structure and environmental impact of continual or episodic oil release. Continued characterization of microbial communities active in the sediment may provide a mitigative action for oil being released into the environment. The residence time of leaked oil in the environment and the nature of its degradation provide site-specific information on long-term impact of the present loss rate, as well as a potential increase or episodic release.

Figure 9. Gas chromatograph traces of USS Arizona oil samples representative for two different locations. The top oil sample shows significant weathering of the oil, most noticeably depletion of n-alkanes in comparison to the bottom sample.

During 2003, a graduate student in MUSC’s Molecular and Cellular Biology and Pathobiology Program in the Marine Biomedicine and Environmental Sciences Department, Ms. Amanda Graham, completed a Master’s thesis entitled The USS Arizona and Bunker C Fuel Oil: An Environmental Study. Research for this study was conducted in partnership with NPS-SRC and supported in part with Legacy funds. The thesis research, using samples provided by SRC, focused on a preliminary environmental assessment of the oil leaking from the USS Arizona and determining if aerobic microbial degradation processes are influencing oil composition. The hypothesis of this study is that oil leaking from different areas of the ship has different chemical profiles and chemical composition and is degradable by aerobic microbial communities in surrounding sediments. Graham characterized the oil leaking from different areas of USS Arizona as well as the oil contamination in sediments surrounding the ship and established fuel oil biomarkers present in oil leaking from the ship and in the surrounding sediments. She also researched aerobic degradation and how these processes affect the fuel oil biomarkers. This study contributes to environmental and conservation management issues regarding the USS Arizona and the prediction of potential environmental impact to the surrounding area if a larger release of oil occurs (Graham 2003).

In addition to laboratory analysis, NPS-SRC researchers collected additional oil samples and bacterial samples during November 2003 fieldwork for continuing analysis at MUSC (Figure 10). These samples are currently being cultured and their DNA extracted for identification.

Figure 10. Microbial colonies on oil in cabin overhead sampled in November 2003. National Geographic photo by Emory Kristoff and Keith Moorehead.

In addition to analysis of oil and microbes, NPS researchers measured the amount of oil escaping from the ship at several locations. This was done to quantify the leakage rate for long-term monitoring to see whether specific location oil leakage is stable or increasing. The device used for quantitative monitoring is a customdesigned oil catchment device (OCD) provided by USIA, a corporate partner. Based on qualitative observations, the primary escape point during the 1980s was a single hatch on the port side of Barbette No. 3. This point was measured in 1998 and a rate of 1.0–1.5 quarts per 24 hours was established. Since 2000, at least two additional leak points have been observed. In November 2003, NPS archeologists measured oil escaping from two primary leak points—one of which was the hatch on the starboard side of Barbette No. 3 that was measured in 1998 (Figure 11). The other was a hatch on the starboard side of Barbette No. 4. Slightly less than 1.0 quart was recorded in a 24 hour period from the hatch adjacent to Barbette No. 3, which means there has been no net increase in oil release at this point since first measured in 1998; in fact, somewhat less was recorded in 2003 than in 1998. The hatch to starboard of Barbette No. 4 had 1.3 quarts recorded during each of two 24-hour collection periods. These points will be monitored periodically, as will any new release points.

Figure 11. Oil catchment device deployed on hatch to starboard of Barbette No. 4.

INTERIOR INVESTIGATIONS

In November 2003, VideoRay ROV interior investigation of Arizona continued. The goals of interior investigation are to search for access to lower decks where oil bunkers are located, visually characterize variations of interior corrosion, and to collect environmental samples and measurements to quantify interior corrosion. November fieldwork focused on the latter task. The VideoRay was equipped with a YSI multiparameter sonde to measure pH, temperature, salinity, dissolved oxygen, oxygen reduction potential and conductivity (Figure 12); and a GMC corrosion potential (Ecorr) probe to collect corrosion measurements necessary for characterizing interior corrosion processes. Investigations were focused on second deck cabins accessible via open portholes and inside Barbette No. 3. Baseline measurements were collected outside each open porthole, and then a separate file was collected inside each cabin at various locations along vertical profiles. All VideoRay operations were recorded, and video time code was used to collate ROV location to specific measurements from both the YSI and GMC instruments. The VideoRay did not have the ability to carry both instruments simultaneously, so we first completed the YSI survey then conducted the GMC recording of the same interior spaces.

Figure 12. VideoRay ROV equipped with YSI sonde entering porthole on Arizona’s second deck.

In general, we found that most parameters recorded with the YSI sonde were nearly the same inside the ship, at least on the second deck level, as outside: pH was 8.0–8.1, temperature about 80–81º F, salinity approximately 33.5 parts per thousand (ppt). Dissolved oxygen (DO), however, dropped dramatically upon entering the ship. Outside, DO levels were about 86–88% saturation; typical levels inside were around 65–68%, and in some instances dropped considerably lower than this. One of the more interesting observations is that interior cabin water is stratified by a subtle thermocline of about 0.5ºF—DO levels, however, change significantly across this thermocline, from nearly 70% saturation above to about 50% saturation below the thermocline. This indicates very little water movement within interior cabins, even with open portholes. Researchers are looking into what effect this has on overall interior corrosion rates and affect on microbial colonies.

GMC corrosion potential measurements are still undergoing analysis. Preliminary findings indicate that interior values are 10–18 millivolts (mV) more positive than baseline readings outside each cabin. This could indicate a slightly higher corrosion rate, however there are many variables at play here, and a thorough analysis of the data is necessary before drawing any conclusions.

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