Photo: Terry Kerby/ Hawaii Undersea Research Lab
A University of Hawaii deep-diving submersible examines munitions discarded five miles south of the entrance to Pearl Harbor. UH and Army scientists spent 15 days earlier this month mapping the location of munitions dumped in the ocean at a deep-sea disposal site off Oahu.
Army analyzes data from offshore dump
Sonar finds that old munitions lie in “long trails” off Waianae
By Gregg K. Kakesako
POSTED: 01:30 a.m. HST, Apr 05, 2009
Army officials hope to have the results in about six months of tests on water and sediment samples collected during a 17-day, $3 million investigation at a military munitions disposal site five miles south of Pearl Harbor. “We were extremely pleased with the results of the survey effort,” said Tad Davis, deputy assistant secretary for Army Environment, Safety and Occupational Health. “We think we learned a tremendous amount of the technology and what it can do for us … the samples have been sent out to determine if there are trace elements of explosive materials or chemical warfare materials.”
Earlier this month, the University of Hawaii’s two deep-diving submersibles found “several thousand munitions” at depths of 1,500 feet over 240 square miles, Davis said. By comparison, Davis pointed out that the Empire State Building in New York City is 1,400 feet tall.
However, scientists failed to uncover a large cache of munitions.
UH principal investigator Dr. Margo Edwards said: “When we analyzed the sonar data, we saw long trails of reflective targets that we suspected were munitions discarded from a ship as it steamed forward. We were thrilled when the submersibles confirmed this hypothesis. The fact that munitions were discovered in trails, rather than a large pile, makes sense given how ships were navigated at the end of World War II and the fact that ships roll less when they steam into the seas.”
The water and sediment samples collected by the Hawaii Undersea Research Laboratory’s three-man submersibles, Pisces IV and V, will be sent to the Army’s Edgewood Chemical Biological Center and UH and mainland laboratories for analysis of metal content, explosive compounds and chemical agents. Fish and shrimp samples are also being analyzed. The Army believes 16,000 M47-A2 bombs containing 598 tons of mustard gas were dumped in the area, now dubbed Hawaii-05, on Oct. 1, 1944. Each chemical bomb weighs 100 pounds and is nearly 32 inches long. The practice of ocean dumping was banned in 1972. Davis said the Army also will decide over the next six months whether to make onsite inspections of the two other suspected deep-water chemical munitions dumpsites.
Between 1932 and 1944, chemical weapons such as blister agents lewisite and mustard gas and blood agents hydrogen cyanide and cyanogen chloride were discarded in waters off Oahu. The largest dump is reported to be in an area 10 miles west of the Waianae Coast.
University scientists and students also will use the sonar data to map the area and pinpoint the location where munitions were found.
The Pentagon has determined that besides Hawaii, there were 19 chemical weapons sea disposal sites — in the Atlantic Ocean, the Gulf of Mexico, off the coast of Alaska and two instances in the Mississippi, near Louisiana.
The Army has said that it does not plan to remove any of the chemical weapons because there is no data to indicate that they pose a threat to human health or the environment.
Davis said the deep-sea survey is also drawing on the experience and methodology used in another long-term project on the Waianae Coast, where the military already has spent $2.2 million to determine the effects of the dumping of 2,000 World War II-era conventional weapons on the sediment, shellfish, limu and fish near Ordnance Reef. The term “conventional” refers to munitions that are not nuclear, biological or chemical.
At Waianae, the Army’s goal is to clear the water from the shoreline to 120 feet offshore.