In the late 1970s, radioactive material from atomic weapons tests done 30 years prior was dumped into a 100-metre wide bomb crater and then covered with concrete.
It was the site of the largest nuclear clean-up in United States history.
The Marshall Island's Red Cross Secretary-General Jack Niedenthal said the site is still highly radioactive and locals want the waste gone.
"No one would ever tolerate this in their back yard. There's a very serious situation up there, but we just can't seem to get anyone to pay attention to it."