Abandoned Mine Leads to Sinkhole in Subdivision 1

[TigerGuy]

https://www.kotatv.com/2021/11/10/l...study-shows-all-153-houses-are-uninhabitable/

Time for another lively discussion: Where does the fault lie?

Homeowners have been evicted from their residences, due to an abandoned underground mine opening up right under their neighborhood. I don't have all the details, but I am familiar with the area where this is taking place. Allegations include the mine not being properly closed, engineers designing over the mine, title companies that didn't do proper research on the property history, building officials granting building permits, the list goes on and on.

The reporter says in the attached story that the mine turned the land over to the county or state with the stipulation that it only be used for grazing.

Your thoughts? Go!

 

[waross]

The original mine may have been an open pit. Information that I have found is not definitive but it is possible that at least part of the mine was open pit.
If so, material was brought in to back fill the pit.
If that was the case, then it may be sinkholes developing in unsuitable fill. That is fill that easily carried into lower aquifers by water percolation. (Is that the correct word?)
Grouting may not help if the overburden is subject to developing sink holes.
I am waiting for the results of the ongoing drilling before forming an opinion on what actually happened.
Now is speculation.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[1503-44]

Either way, the turnover conditions will normally carry significant weight, as long as all other existing laws were followed.

 

[spsalso]

I did a search for "hideaway hills black hawk sd" and found lotsa information.

Appears the big physical problem is mine tunnels about 15'-20' down. The legal problem appears to be that the county owned the land and knew about the mine tunnels and allowed the construction of houses on top. And there's a lawsuit against the county.

There's apparently many millions of dollars available to compensate the house owners.

So the term "slam dunk" comes to mind.



spsalso

 

[DrZoidberWoop]

We tried to pitch expandable concrete backfill for mines as a carbon sequestration and fiber-optic-based monitoring research project. There are many products for expansion curing; the simplest is powdered aluminum + water, which is not a good option because Al is a main ingredient in many explosives. The energy company, which I won't name, wanted nothing to do with the general concept, at all. Their hands were already tied by the EPA and they had no interest in anything that could put them under the gun for affecting, or perhaps further affecting, groundwater. They wouldn't even buy into using coal-ash as a component of the backfill because they were waiting for the EPA to make a ruling whether to classify it as toxic, or not. That was a pretty brutal meeting. Lawyers rule that world.

 

[waross]

Appears the big physical problem is mine tunnels about 15'-20' down.

Not to contradict, because you found it on the net.
"15'-20' down" does not correlate with reports of the depths of the sinkholes.
(This is not sarcasm nor a personal attack spsalso, it is more a comment on the credibility of "I found it on the net".)
After my own google search I am waiting for the results of the ongoing drilling.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[spsalso]

I based my 15'-20' on this:

Link

and this:

Link

It is certainly true I didn't spend much time on this.


spsalso

 

[waross]

We tried to pitch expandable concrete backfill for mines as a carbon sequestration

That comment takes me back a few years to a comment made by "Little George".
During his time in office "W" announced that his administration was moving forward with plans to sequester coal.
My immediate thought was;
"Great idea. You can probably sequester the coal in abandoned coal mines."
That said, I imagine that an abandoned gypsum mine may work just as well.

Various websites.

And as I say, we’re in a period of transition
here in America, from a time where
......
and a time when
we can sequester coal.

I still wonder why he didn't show up for that medical exam.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[waross]

Thanks for sharing those links spsalso.
I hope that that cutaway drawing is accurate and not an artist's conception.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[spsalso]

Well, the cutaway drawing kinda agrees with the photograph.




spsalso

 

[Roga50]

Interesting site with underground pictures of the mine and the map the cavers developed.

https://www.pahasapagrotto.org/hideaway-mine.html

There even appears to be an old car under there?

 

[spsalso]

Sure wouldn't have hurt if they'd explained the difference between the sandy-with-weeds overlay and the water-looking-blue overlay. Right now, it looks like an underground beach. Won't need sunscreen, though.

It IS neat how they did the exploration, though!


spsalso

 

[zeusfaber]

There's a link to a larger copy of the map - complete with a key on the "Maps" page of their website.

 

[ACtrafficengr]

If they are 15-20 feet down, and the tunnels and galleries aren't too high, I wonder if it would be cheaper to collapse them with explosives and backfill on top. The land would probably still be unbuildable because of uneven settlement, but at least it would stop most of the sinkholes.

We had problems this fall with an abandoned wooden aqueduct that finally collapsed. Who knows what lurks beneath our feet?

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. -

http://xkcd.com/319/

 

[1503-44]

That will take care of the problem houses built on top too.