Feds want to bury Johnston Island's radioactive matter
By Jan TenBruggencate
Advertiser Science Writer
A federal agency hopes to entomb nearly 60,000 cubic yards of radioactive material on Johnston Island.
The burial and covering of the contaminated coral and construction debris has been proposed as the best of multiple disposal options by the Defense Environmental Restoration Program.
Officials with the program will hold public hearings in Hawai'i this month on its proposals. The hearings will be preceded by a one-hour meeting during which technicians will discuss the plan.
Sessions are March 13 at the Lihu'e Public Library on Kaua'i, March 15 at the Kahului Community Center on Maui, and March 18 at the Pu'u'eo Community Center in Hilo on the Big Island. Times for the Neighbor Island events are 5 to 6 p.m. and 6 to 8 p.m. The Honolulu sessions are 5 to 6 p.m. and 7 to 9 p.m. March 20 at Washington Middle School.
Johnston Atoll, 700 miles southwest of Honolulu, was the site of two aborted nuclear test missile launches in 1962. The destruction of the missiles left Johnston Island, the largest land mass within the atoll, contaminated by plutonium oxide and americium, a radioactive breakdown product of plutonium.
The cleanup of the radioactive contamination has been going on for the past 40 years, resulting in four piles of contaminated material:
- Nearly 60,000 cubic yards of coral with an average radiation concentration of 200 picocuries per gram — a level of radioactivity that under Environmental Protection Agency regulations must be sealed from exposure to the environment.
- 156,000 cubic yards of coral contaminated at an average of 7.7 picocuries per gram — below the level requiring special treatment.
- 240 tons of metal and 260 cubic yards of concrete debris, whose radioactivity is assumed but untested.
The Defense Threat Reduction Agency proposes using an existing excavation within the Radiological Control Area, the region directly contaminated by the missile blasts. It would dump in the metal and concrete debris first, followed by the higher-level contaminated coral. It would be capped with a 2-foot layer of coral soil.
The area would then be subject to land-use restrictions and regular monitoring for up to five years.
"This combined option provides an approach that protects human health and the environment commensurate with the radiological risk, and offers cost-effectiveness and practicality for this remote location," the agency said.
Other alternatives include different landfilling options, shipping material off the atoll, encasing it in concrete, and vitrification — essentially, turning it into glass before burying it.
The EPA set a radioactivity level of 40 picocuries per gram as an acceptable risk level for the atoll, but the Defense Threat Reduction Agency selected a technique that allowed it to achieve 13.5 picocuries per gram as the standard islandwide.
The radiation risk for people on the island for one year at this level, the agency said, is slightly less than the radiation dose an airline passenger receives flying coast to coast.
A May 2000 survey "verified that plutonium oxide is not soluble in the Johnston Atoll environment and that groundwater has not moved radioactive contamination from the Radiological Control Area to other parts of the island."
Of 113 core samples taken around the island, all but five showed contamination levels lower than 13.5 picocuries per gram, and four of those five were below the surface.
The fish in the lagoon are edible and contain no more radioactivity than fish sold in Mainland U.S. markets, the agency said.
