I haven't read up on that in a while, but I thought the process of clearing had been started. Maybe even completed, or to certain extent.
It started in the 90's, but wasn't a major clean up. More like volunteer type of numbers. My mom who was with the AG at the time and went there as a group for the office to visit it.
1 issue was that 1 of the big bombs dropped messed up their underground water source. Think of it like jar of water, half fresh water and half salt water. And the 2 separate leaving the fresh water at the top and the salt water at the bottom. Then shake the jar. That is basically what happened with the force of the explosion. But with today's tech, maybe salt water to fresh water conversion is possible if only a small amount is needed. Like enough to run a prison and not a city.
Then due to having no buildings, the wind is very strong because there is nothing to block it. And add in all the dirt/dust.
A prison doesn't have to be in the middle of the Island, but more near the edge where there is less ordinance used. Then have a ferry service, but watch out fo da whales. So a prison is possible, but HI rather spend $12 billion on a rail.