Long wall mining

homeinwestIL · Feb 22, 2005

My mother and aunts are facing the prospect of having a long wall coal mine go in under some farmland that they now own--my grandparents' old farm--in southern Illinois. The situation was that a coal company had bought up mineral rights years ago (mostly in the 60s I believe) but recently gave all their rights to the county to avoid paying taxes on them. The county decided then to sell (or lease) those rights to another coal company who is now making serious plans to open a mine in the area. The farmers in the area are obviously irked that the county didn't offer the mineral rights back to the surface owners to avoid potentially damaging mining activity in the area. Has anyone had experience with long wall mining? How damaging is this to the surface? I understand there is more subsidence with this type of mining than with traditional techniques. My mother and aunts are concerned that this subsidence will turn their most productive bottom land into marsh and make much of the rest of the land unusable for production. I expect it can destroy houses and barns too. I presume there are federal and state regulations on these activities. Any information would be appreciated. All of this makes me very thankful that I own the mineral rights under my own land.

Birdhunter1 · Feb 23, 2005

I don't know what it does on the surface but I know when the shields move all 800' above falls in behind the shields at the long wall miner as everything moves. Very COOL to watch.

By chance is this mine property over around Saline County/Raleigh/Harco/Galatia area? That is the only long wall machine I know of in So. IL, I hae seen this one in operation just a few feet in front of my face. I had an industrial electorincs course a few years ago in Community college and we toured the (use to be called Curr-McGee) mine near Galatia which is all underground. We got to see the entire operation, they have a long wall and a continuous miner over there, both were cool. The mantrip vehicles were cool too, I want one.

I may be able to find out from some guys I work with that live in the area I described and find out what happens on the surface but I imagine it gets roughened up a bit, to say the least.

goodoleboy · Feb 23, 2005

Im not sure what long wall mining is but my Inlaws live on some land that was mined in the 50's and there are sinkholes 300ft wide and about 125ft deep. Not really much you can with the area if it gets a sink hole. They found some whole trucks, bulldozers etc. down their it actually runied the water well beucase of the gas and oil that leaked out of the machines over the years.

For all i know I could be on top of mined ground. It would be cool to find a map of mined areas and go for a hike (if it was safe).

OkeeDon · Feb 23, 2005

I didn't know what long wall mining is, so I did a Google search and did some reading, just because I was curious. It appears that the ground above the mine can settle 4' or more as the mine moves on. Apparently, the difference between long wall mining, and room-and-pillar traditional mining, is that both will have roof collapses and surface subsidence, but with long wall mining it's predictable (it IS going to happen, and right now!) while with traditional mining, no one can predict when the pillars will collapse and the surface subside. The randomness of traditional mine collapse is apparently what causes sinkholes.

Reference was made on one site to development; they said, after the surface has subsided over the long wall process, the land can be safely developed with buildings, while no one can predict what will hapen with buildings over a traditional mine. Apparently, for this reason, the mining companies have some sort of insurance or fund for buildings over a traditional mine, while they don't have such for a long wall mine. This seems to infer that they don't do long wall mining under existing buildings, but they didn't really say that, and I didn't read enough different sites to get any corroboration.

It's an interesting subject (providing you're not directly affected), and thanks for bringing it up so I could learn something.

LKGuy · Feb 23, 2005

I used to inspect the surface effects of a longwall mining operation in SE Ohio. The amount of damage that may occur to the surface is dependent on many factors such as: depth of coal being mined, type of rock formations that exist between the coal and the surface, the width of each pannel being mined, and the thickness of the coal seam. Typically, the deeper the coal, the less surface subsidence is seen. The opereation I inspected was mining coal 250 to 350 feet below the surface. To visualize how a longwall mine looks after the coal is removed, imagine a hammock. The two ends are supported but the middle sags. In a longwall mine, the two ends are where the coal is brought out so it is room and pillar mining and it is not totally mined out (usually, but it can be in really agressive mines). Now to visualize the surface effects of longwall mining, at the support ends of the mines (hammock) where the sag is greatest, cracks can open up because the ground is being streached. But in the middle of the sag the ground is being compressed. To surface structures such as houses, this can cause foundations to shift. I have watched surface cracks open up and then close, streams go dry and then reappear, telephone lines streatch as tight as banjo strings as poles shift, ponds empty or just shift so that water starts to flow over the embankments. The coal company tried to be good to surface owners but they could only do so much. Ahead of the mine they would offer to buy people out, or support the house so the house could ride out the ground shift. The main thing the coal company could do little about was when a stream, spring or well was destroyed by the mining. You can't bring surface water that is flowing into a crack back to the ground, you can't make a rock formation hold water when it becomes highly fractured, and you can't make ground water drinkable again if the quality is messed up. Only nature can over a long, long time. I would spend a lot of time talking to your State Agency that regulates mining and also contact the Office of Surface Mines (OSM). They are the federal agency that enforces the Surface Mining Control and Reclamation Act (SMCRA) that regulates mining in the US. A lot depends on the coal company. I was lucky, the coal company I regulated whet above and beyond what the law required, while other coal companies at the time were doing nothing but trying to do as little as possible. Good luck.

Birdhunter1 · Feb 24, 2005

The mine in question, the one that I toured (which I believe is the same mine), was about 750'-800' below the surface when I was there 4 years ago. I dated a girl a year ago who's dad worked at that mine and they were about the same distance below the surface then.
The seem they are mining is BIG to say the least.

I just reread the original post and realized the mine he is aksing about is not a mine in currently in operation.
Is this the mine with a power plant on the surface that is going in near Nashville, IL you are talking about?

homeinwestIL · Feb 24, 2005

The proposed mine that I am talking about is in Montgomery County. I think they are at the early planning stages--probably three or four years from production.

Birdhunter1 · Feb 27, 2005

Not familiar with the area. From what I have read in other areas of the internet it does disturb the top depending on how close to the surface the mine is.