EPA + DOH reject Navy’s Red Hill corrosion study
In March, the U.S. EPA and Hawaiʻi Department of Health issued a joint letter to the U.S. Navy rejecting the Navy’s recent corrosion analysis report for the Red Hill tanks. This corrosion analysis took 10 steel liner samples from Tank 14, scanned them, and then estimated how thick the tanks were and identified where repairs were needed. The Navy’s corrosion analysis process resulted in a 40% error rate. 4 out of the 10 samples were inaccurate—both under and over estimating tank liner thickness, either missing areas that should be repaired, or identifying areas where tank repair was not actually needed. In addition, 40% of the time the Navy’s measurements were more inaccurate than the goal set for +/- 5% error, further highlighting the level of inaccuracy of the Navy’s current process. To top it all off, in the Navy’s report summary they ignored some of these inaccuracies and misinterpreted some of the corrosion test results.
“The Navy’s laboratory analysis did not or was not able to identify the thinnest portions of each plate which made a good portion of this destructive destiny exercise and analysis incomplete.” (page 3)
The regulatory agencies also took issue with how the Navy estimated the tank corrosion rate and believe the Navy is underestimating how quickly the tanks are deteriorating. 7 of 10 samples showed both low pH and high levels of chloride ions, which both accelerate the corrosion of steel. The regulators believe that only one of ten coupons have a low probability for corrosion, while four of the ten coupons indicate active corrosion.
“The Regulatory Agencies believe that there is greater concern for corrosion and the potential for increasing corrosion than the Results Report implies.” (page 6)
After rejecting the Navy’s report, the Navy has 60 days to meet with the EPA and DOH for a scoping meeting. The Navy will be required to determine how to better evaluate and improve their corrosion testing process so that it is more accurate and effective.