South Dakota sink holes

lunkerslayer

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Christopher Pelczarski is a caver, and he’s seen a lot of underground passageways. But he’s never seen anything like the abandoned gypsum mine that was exposed by sinkholes this week in Black Hawk.
For one thing, he never expected to find a car down there.
“There was one place where there is actually literally a car coming out of a hole from the surface, an old car. It’s like a 1951 Ford,” Pelczarski said. “Yeah, it’s half sticking out of the ceiling, basically.”


He figures there used to be a scrapyard or garbage dump on the surface, and the car somehow sank down from there.
There are two sinkholes as large as 40 feet wide in the yards of a residential neighborhood of Black Hawk, just north of Rapid City. Local officials have evacuated at least a dozen homes.


Pelczarski is a member of a caving club called the Paha Sapa Grotto. Club members volunteered to explore the mine and use their expertise to measure and map it. Their efforts will help authorities pinpoint danger spots.


The cavers mapped 2,300 linear feet of passages, Pelczarski said. There were additional tunnels they couldn’t access because they were flooded or collapsed. Some of the tunnels were big – 12 feet high and 40 feet wide.


The ceiling at one place in the mine was 30 feet above their heads, indicating a potentially thin surface above.


“Being experienced at traveling underground, we were cautious to go in,” Pelczarski said, “but we recognized somebody needed to do this, and we’re the ones that have expertise in that area.”


Besides the car, the cavers also found old mining equipment.

“There are places you can see old rail-car tracks from the mining operation,” Pelczarski said. “There’s wood that’s just to the point where it looks like a piece of wood, but then you step on it and it just mushes like paper pulp.”


The mine apparently dates to the early 1900s. It’s unknown whether the neighborhood developers knew what was underground.








f2385ece19_Black Hawk sinkhole (1).jpg
 


Traxion

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Heard about this a few weeks ago. Guessing will be a huge lawsuit against the developers.

Something along the lines of 75 million I think. Developers, county, state, are all involved. State had mining permits on it. County did too and part of the application for the development included a note that test holes should be done. It's going to be messy, but if the burden of proof is known or should have known I think they have a solid case. The old timers in the area all knew it was there.
 

sl1000794

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Every housing project we built in CA required a soils report that would have included soils borings that would have found these sinkholes.
 

Traxion

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The note in the development application apparently stated there may have been a mine and test holes should be done. But, it was also noted no obvious depressions or issues were noted at the time.

Western SD at the county level= stone age/wild west/no regulation. At least in comparison to anything in California. Pretty close to a free for all out here. And we have plenty of geological issues, most notably fatty clays and expansive soils, that would benefit from soil testing and boring. But it adds cost and is "over regulation" according to most. I've seen tons of issues related to this but people don't seem to want to fork out the $$$$.
 


Davey Crockett

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We have a lot of them here in western ND. Old underground coal mines that have swallowed 4 wheel drive tractors.
 


fireone

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We have a lot of them here in western ND. Old underground coal mines that have swallowed 4 wheel drive tractors.
I've heard of that but never seen them. Are they mapped too? I knew of a guy in NM that had a dog drop in when quail hunting. Quite a project to get his dog back.
 

Davey Crockett

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Yes, They are mapped and the state bids out contracts for the reclamation projects. There is a federal tax on the coal coming out of the ground and funding for this year is 2.8 Million.


https://billingsgazette.com/news/st...cle_8487817b-7a82-52af-b499-b60c15abf318.html


https://psc.nd.gov/docs/amlarticles/ndakota.pdf[/URL]

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https://psc.nd.gov/docs/amlarticles/ndakota.pdf

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The PSC link won't post as a clickit but it's loaded with information and pictures.
 

dean nelson

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The old Wilton mine is easy to spot due to all the sinkholes.

Screenshot_20200605-212438.jpg
 
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Kurtr

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I know about 11 years ago when I was working up there 1000s of yards of flowable full was being pumped into those old mines so they didn’t collapse
 


Davey Crockett

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Amazing how they had the foresight to tax coal for environment clean up issues but not oil. That's shady and greasy.
 

Davey Crockett

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I know about 11 years ago when I was working up there 1000s of yards of flowable full was being pumped into those old mines so they didn’t collapse


Was there a drill rig on site or just a borehole and a grout pump ? I threw in a bid one year and missed it by a country mile and never looked back. I've never seen it done.
 

Kurtr

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Was there a drill rig on site or just a borehole and a grout pump ? I threw in a bid one year and missed it by a country mile and never looked back. I've never seen it done.

they bored two holes one for the grout pump and the other they used to see the fill come out of to know they are full
 

dean nelson

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Still seems so weird to me when I see these pics and realize this is Wilton! You couldn't pay me enough to go underground in North Dakota with how alluvial our soils are!

1668743796391.png1668743796391.png
 


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