Addressing munitions in the sea: Lessons from the Hawaii undersea military munitions assessment

It has become necessary in many locations to understand the distribution and condition of munitions, most of which have been corroding in the saltwater environment, and to determine the effects of their internal components on the surrounding environment. In 2007, the United States Department of Defense (DOD) established a program to investigate munitions in the region south of Pearl Harbor, Oahu, Hawaii. The project, entitled the Hawaii Undersea Military Munitions Assessment (HUMMA) focused on DOD sea disposal site HI-05, an area characterized by water depths of 300 to 700 m. Archival research indicated that 16,000 M47A2 100-lb. mustard-filled bombs were likely to have been disposed in this region during October and November 1944. In 2009 and 2012, the UH Pisces submersibles (human-occupied vehicles, or HOVs) gave HUMMA researchers close enough proximity to image thousands of munitions at the centimeter scale and collect sediment, water and biota samples within 2 m of 39 chemical and conventional munitions and control sites. HUMMA produced an extremely large integrated data set, combining remotely sensed data with physical samples of sediments, biota and water, making it the most comprehensive deepwater investigation of sea-disposed munitions undertaken in U.S. waters.