Posted on: Friday, October 18, 2002

Story of atoll's radioactive past about to be closed

By Jan TenBruggencate
Advertiser Science Writer

For further information More information on the Johnston Atoll landfill is available on the Web at www.dtra.mil/news/nw_index.html.

Defense Department crews have buried radioactive material within an existing excavation on Johnston Island and are awaiting radiation tests before sealing the landfill.

They hope the action will mark the final chapter in the military's toxic relationship with one of the world's most isolated atolls, located 717 nautical miles southwest of Honolulu. The Army is closing the Johnston Atoll Chemical Agent Disposal System now that the nerve gas and blistering agent munitions once stored on the island have been destroyed.

It has been four decades since a series of nuclear rocket failures drenched the island in radioactive contaminants.

Ironically, Johnston has been a national wildlife refuge since 1926. It is a nesting ground for threatened green sea turtles and more than a dozen species of sea birds and migratory birds, and its waters are home to 300 species of fish.

The Navy took over the atoll in 1934, and the Air Force subsequently assumed control in 1948. The site was used for high-altitude nuclear tests in the 1950s and 1960s before it was maintained as a storage and disposal site for chemical weapons until 2000.

On June 20, 1962, Starfish, a Thor missile with a nuclear warhead, was blown up directly over Johnston when it failed one minute after launch. Metal parts and debris fell back onto the island. A month later, on July 25, a launch dubbed Bluegill Prime was destroyed on the launch pad, scattering radioactive material.

Neither explosion was a nuclear detonation, but the radioactive material in the warheads was widely distributed. Divers picked up the debris they found on the lagoon floor and the contaminated runway was torn up and piled near the launch site. Some material was hauled down a ramp made of contaminated coral, loaded into landing craft, and taken out to the channel to be dumped in the deep ocean. Special equipment was used to identify and collect particularly "hot" particles and separate them for special treatment.

After a series of studies and public hearings in Hawai'i earlier this year, the Defense Threat Reduction Agency concluded that the best alternative was simply to bury the most radioactive material and cover it with coral debris of relatively low radioactivity. That work started this summer and is nearly complete.

"The contaminated metal and concrete debris, and coral that did not meet the cleanup standard, were buried in the Radiological Control Area under a cap of clean coral soil that is a minimum of 2 feet thick," said Cindy McGovern, public affairs specialist for the Defense Threat Reduction Agency, which is overseeing the cleanup.

She said the agency is now conducting a radiological survey to be sure the site meets requirements set by the Environmental Protection Agency.

An estimated 45,000 cubic meters of now-buried coral has an average radioactivity of 200 picocuries per gram. Under EPA rules, material with that level of contamination must be sealed from exposure to the environment. The 240 tons of radioactive metal and 200 cubic meters of concrete debris has not been tested, but they are assumed to be contaminated.

All that material was covered with a 2-foot-thick cap of coral that has a far lower level of radioactivity — an average of 7.7 picocuries per gram. That level does not require special treatment under EPA rules.

The EPA set the Johnston Atoll cleanup standard at a radioactivity level of 13.5 picocuries per gram. At that level, the radiation risk for people on the island for one year is slightly less than the radiation dose an airline passenger receives flying coast to coast, federal officials said. Some types of home smoke detectors contain materials with levels of radioactivity several times higher.

The anticipated human exposure from the rocket explosion debris on Johnston is considered to be a fraction of the "average annual radiation dose to the U.S. public from all sources (natural and man-made)," according to a fact sheet on the project prepared by the Defense Threat Reduction Agency.

The contaminated landfill will be compacted and its surface shaped to shed rainwater, although tests suggest radioactive materials are not soluble in Johnston's coral soils, and are not leaching into the waters at the atoll.

Once the project is complete, the Defense Threat Reduction Agency intends to regularly monitor the landfill site for five years.

"If any radiological contamination is found after landfill monitoring is completed, the contamination will be evaluated by the DTRA health physics staff and appropriate action taken," McGovern said.

"We are confident that the EPA-recommended cleanup standard will have been met atoll-wide," she said.

The Maui-based Earth Foundation said yesterday it continues to be skeptical of the safety of the landfill method, and feels the radioactive material should be removed from the atoll and hauled to an approved nuclear waste storage site like the one at Yucca Mountain, Nev.

"The problem is plutonium has a half life of 24,000 years and is life-threatening for that entire time. There are places on the mainland that are better-equipped to contain radioactive nuclear waste than an atoll vulnerable to hurricanes and erosion from the ocean," said a statement from the group.

One issue brought up during public hearings in March is the level of threat from erosion due to hurricanes or tsunamis.

The Defense Threat Reduction Agency's corrective measures study, published in June, assumes that the seawall surrounding Johnston eventually will fail, and calculated the threat to the environment if the radioactive landfill is washed into the lagoon.

It concluded that the amount of radioactivity added to the material already in the ocean would increase the radioactivity threat by only about 1 percent — a level it decided was so low that it does not justify the expense of maintaining the seawall.

Biological studies prepared by the military for Johnston suggest the threat from radioactivity to wildlife is very low. The Hawaiian monk seal, which occasionally visits the atoll, would potentially accumulate the most radioacivity, by eating fish that feed around the most radioactive sediments in the lagoon.

Even if a seal fed year-round only on bottom-feeding fish from the most contaminated area of the lagoon, it would reach just 10 percent of the radiation exposure limit set by the International Atomic Energy Commission, said the corrective measures study.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.