The Environmental Protection Agency is saying a mine waste pit in southwest Missouri doesn't appear to be filling, four years after the agency began dumping waste into it.
The Joplin Globe reports the mine, near Oronogo, closed in 1948. It eventually developed into a lake 200 feet deep in some places.
In 2012, the EPA said it would have no problem filling the pit, estimating it would hold about 4 million cubic yards of mine waste.
Mark Doolan, who is supervising the cleanup of the Oronogo-Duenweg Mining Belt Superfund site, said 2.5 million cubic yards of waste have been dumped into the pit but it shows no sign of filling.
Doolan thinks the pit might not be filling because it has several long, deep tunnels at its bottom.