Workers are pushing boulders into the pit. They say it will take two days to complete the task, after the nearly 20 years it took to get there. It was that long ago that radioactivity was discovered on tree stump leaves at the dump site. That led to testing, and it was found that ground water was contaminated.
After that, the site was excavated, ridding it of the toxic waste dumped as far back as 1960.
The pit has now been declared clean, and will be filled with fresh dirt. The waste that was there was put there legally between 1960 and 1970.
"On the outside it looked like a remarkably good approach," said soil expert Dan Richter. "They were very aggressive about a problem that there was a great deal of uncertainty about."
The ground water contamination still exists and will require further testing.