Right. Leaving it alone is never an option for the government. “Meddle In Everything” is their motto.
Leaving the abandoned mine alone was likely not an option. I suspect the state’s Mine Inspector figured out it was a “ticking bomb” and asked the EPA to help, because it was way beyond his resources.
Making it more interesting is that they were afraid it would dump into a different creek, called Cement Creek, instead of where it actually dumped. This might have meant the worst of all possible worlds, a lot of liquid and *under pressure*. It might have already been leaking in that direction.
A lot of liquid implies more liquid is entering.
What it *could* have done is about anything. It might have fractured “up”, making all the ground above it dangerously unstable. It could collapse the walls in any direction. It could even burst “down” pumping all that waste into the water table.
A mining expert I knew described it as “the stick of dynamite in the latrine” scenario.