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“People just weren’t meant to be that far underground.”
August 2, 2011 9:26 AM   Subscribe

Venturing 9800 ft below the earth's surface at Kidd Creek mine
posted by exogenous (36 comments total) 19 users marked this as a favorite

 
Fascinating and a bit disturbing. Great post.
posted by Splunge at 9:39 AM on August 2, 2011


Very neat, thanks!
posted by hackwolf at 9:40 AM on August 2, 2011


Despite my claustrophobia kicking in from the about the first sentence a fascinating read. According to their operations page they're heading down to 10500 feet over the next few years. Incredible.
posted by ntrifle at 9:48 AM on August 2, 2011


I love the low-tech, 3D map.

What's really incredible is how not deep 9800 ft is. That's like the distance from your office to the nearest Starbucks. And in the other direction the story is the same. Just a few miles above the surface is unlivable too. Imagine your town is the bottom of this mine. The next town over is the surface of the Earth. The town after that is so high in the sky you can't breathe the air.

It's very thin skin we inhabit.
posted by DU at 9:55 AM on August 2, 2011 [8 favorites]


9,800 feet is almost two miles. That's far to me. And the only place Starbucks are that far apart is probably 9,800 feet below the surface of earth!

Neat post!
posted by punkfloyd at 10:01 AM on August 2, 2011 [1 favorite]


That's like the distance from your office to the nearest Starbucks.

I don't know where your office is, but here in San Francisco, I'll walk to a different Starbucks if the one I'm at has a long line. If there are 10 people waiting to order, it actually takes less time to walk to a different one.
posted by ryanrs at 10:05 AM on August 2, 2011


Coming up with immediately-identifiable, non-cliche and location-agnostic distance metrics isn't easy.
posted by DU at 10:09 AM on August 2, 2011 [5 favorites]


The difference between two NYC express subway stops?
posted by elizardbits at 10:11 AM on August 2, 2011


A good example of completely non-location-agnostic, thank you.
posted by DU at 10:17 AM on August 2, 2011 [3 favorites]


Just curious, at what air pressure does the human body stop functioning properly?
posted by blue_beetle at 10:23 AM on August 2, 2011


All I know is that it's a lot farther than digging to bedrock in Minecraft.

This was a fun and kind of scary, thanks. A liitle like reading Stephen King's The Mine.
posted by Room 641-A at 10:24 AM on August 2, 2011


Our first geology stop was where the blasting had exited the hard volcanic rocks and entered a layer of sedimentary rock called greywacke

This was at 9,000 feet down. The contact they looked at between the volcanics and sedimentary rock at this depth represents a location that was at one point the surface of the earth, which is now buried between your immediately-identifiable, non-cliche and location-agnostic distance metrics.

Neat post.
posted by Big_B at 10:28 AM on August 2, 2011 [1 favorite]


blue_beetle: You start to get oxygen toxicity at around 6.5 atmospheres of pressure, but can get nitrogen narcosis at 3 atmospheres. That's ~215 feet and ~100 feet underwater, respectively. I don't have time to do the math now, but given the relative density of air and water, I don't think you would approach three atmospheres before you hit the MoHo. Humans live much closer to the outer edge of our air density envelope than the inner edge, I think.
posted by hackwolf at 10:45 AM on August 2, 2011 [2 favorites]


Er, add one to those atmospheres for absolute pressure instead of relative pressure. Since, you know, we have one atmosphere at sea level by default.

At least until MegaMaid shows up...
posted by hackwolf at 10:49 AM on August 2, 2011


That was fascinating. Thanks!
posted by mudpuppie at 10:49 AM on August 2, 2011


Big_B: " The contact they looked at between the volcanics and sedimentary rock at this depth represents a location that was at one point the surface of the earth,"

Hell, in the Teton range, the rocks on the valley floor which match the tops of the peaks are down 24,000 feet. The peaks are 6,000 up - which makes a displacement at that fault of 30,000 feet (9144m for you metric folks)
posted by notsnot at 10:59 AM on August 2, 2011


My nine year old son loves geology. I am going to read this to him tonight.
posted by punkfloyd at 11:00 AM on August 2, 2011


Metafilter: I'll walk to a different Starbucks if the one I'm at has a long line.
posted by borkencode at 11:14 AM on August 2, 2011 [2 favorites]


I love the warning rail that's been defaced in this photo. Adds a lovely human touch to the whole journey.

Linky
posted by ZaneJ. at 11:16 AM on August 2, 2011


notsnot, the highest mountain in the Tetons is Grand Teton (13,770 feet (4,200 m)).

Here is a link to a 4.3 km deep mine.
posted by dances_with_sneetches at 11:16 AM on August 2, 2011


Neat! Thanks for posting this...
posted by ph00dz at 11:23 AM on August 2, 2011


Just curious, at what air pressure does the human body stop functioning properly?

I've always been told that 20,000 feet is basically the limit without oxygen, although with conditioning, it's possible to go higher than that. There have been people who have climbed Everest (almost 30k feet) and K2 without bottled oxygen, for instance.
posted by Kadin2048 at 11:34 AM on August 2, 2011


Oh, and for maximum air pressure, then it's a bit more complex. Oxygen actually becomes toxic once it reaches a certain partial pressure, so you need to breathe increasingly dilute mixes as the pressure goes up. The only situation where I think this is generally encountered is in SCUBA diving.

Normal room air becomes toxic at around 230 ft of water which is just under 100 psi. Beyond that you need to start mixing helium or some other nonreactive gas into the mixture to lower the partial pressure of oxygen. The deepest open-circuit SCUBA dive is apparently 1083 feet, or 468 psi. Supposedly there are some other physiological limits besides oxygen toxicity that you run into beyond that.

But you'd have to go a lot deeper than current mines to run into any of those limits. According to this paper (PDF), it would be only at around 6,000m down that you'd have to worry about decompression, 16,000m for nitrogen narcosis, and 22,000m for oxygen toxicity.

Of course, that assumes the mine is at normal atmospheric pressure for its depth, which might not be the case. I could easily imagine a mine that deep having to be pressurized like a caisson in order to prevent water or toxic gas entry, not to mention just to circulate fresh air for breathing.
posted by Kadin2048 at 11:48 AM on August 2, 2011 [2 favorites]


Beware of creepers.
posted by empath at 11:51 AM on August 2, 2011 [1 favorite]


The depiction of the heat underground reminded me of Jules Verne's Journey to the Center of the Earth.

The Kidd mine is partially cooled by using cold winter air to make huge quantities of ice in the winter, which is then used to cool air for the mine during more temperate months.
posted by exogenous at 11:51 AM on August 2, 2011


The mine linked to by dances_with_sneeches appears to be the deepest a person could go below the land surface of the earth. However, there have been several human descents to the bottom of the Mariana Trench in the Pacific Ocean, the deepest to 10,916 m (35,814 ft), in a diving rig.

On the natural side of things, the deepest cave descent has gone down to 7,188 feet. Note, however, that this is surface-to-bottom, not below sea level. (Same at Kidd Creek mine, which is at surface elevation of 917 feet. So the descent to 9800 feet is really to 8883 below sea level).
posted by beagle at 12:32 PM on August 2, 2011


notsnot, the highest mountain in the Tetons is Grand Teton (13,770 feet (4,200 m)).

...but the surrounding ground level they rise from is about 7000 feet, so the vertical rise is about 7000 feet to the highest peak.
posted by ROU_Xenophobe at 12:48 PM on August 2, 2011


As someone who once spent an entire summer digging a hole in our backyard and probably got at most seven feet down, I'm blown away.

Does anybody know:

- Is there anything special about the geology there that lets them dig so deep, or could you dig this hole most anywhere?

- What are the valuable things down there that make it worth all the digging?
posted by benito.strauss at 1:31 PM on August 2, 2011


What are the valuable things down there that make it worth all the digging?

Wikipedia says, "The mine produces copper, zinc, and several other metals."
posted by exhilaration at 1:50 PM on August 2, 2011


You think that's scary? Just wait till you discover what they used before elevators became commonplace in mines. (Video in German here, though you don't really need to understand the language to watch it)
posted by ymgve at 2:06 PM on August 2, 2011 [2 favorites]


- Is there anything special about the geology there that lets them dig so deep, or could you dig this hole most anywhere?

If the resource is there and it is valuable enough, you can dig anywhere. As long as you can make money doing it.

- What are the valuable things down there that make it worth all the digging?

As noted above copper, zinc, and other metals. I don't have any personal knowledge of this mine, but from googling it appears to be a massive sulfide mine. Basically they are mining metals that were precipitated out of hydrothermal waters. At some point someone found the surface deposit at this location, and they just kept mining the "plume" (not really a mobile plume now probably) down through the depths.
posted by Big_B at 4:35 PM on August 2, 2011


They dig too greedily and too deep.
posted by Vindaloo at 5:20 PM on August 2, 2011


ymgve, that is both like genius and dangerous as hell.
posted by uni verse at 6:29 PM on August 2, 2011


"The mine is the deepest base metal mine in the world. The maximum depth of almost 10,000 feet (3,000 m) and its northerly latitude mean that the bottom of the mine is the closest accessible point to the centre of the Earth. Although some South African mines, such as TauTau are deeper, the greater equatorial radius of the earth mean that they are further from the centre." -- from the wiki article
posted by warbaby at 7:57 PM on August 2, 2011


On deep mines - South Africa has mines that go down around 4km or 13,000ft. There are two main issues for humans operating at these depths: 1. Heat. There's a big industry in mine air-conditioning. Most mines in Australia have either airshafts or kilometres of plastic tubing running from the surface attached to enormous fans that pump cool air down into the mine. 2. The dangers of rockbursts, rockfalls, cave-ins etc, which kill thousands of miners around the world each year.

- Is there anything special about the geology there that lets them dig so deep, or could you dig this hole most anywhere?


Aside from the economics of the orebody, what determines the depth of a mine is the stability of the rock and the "seismicity" that you encounter at depth which very much has to do with what sort of rocks you're dealing with.

The deeper you go, the more pressure or stress there is from the earth on all sides of the shafts, declines and stopes, meaning more rock fracturing, more seismicity, more instability, more danger etc.

That's why the air pressure conversation above made me chuckle - it's not the air pressure that's the problem, it's the rock pressure. When you're 1km underground that's 1km worth of rocks pressing in on you from every direction.

Here in Australia, our deepest mines are around 1800m deep and at these depths managing ground conditions is a very, very big concern. The rocks we have here are inherently less stable than the rocks in South Africa (vast oversimplification that would make geologists wince, but I'm running with it) so that means we have the same ground control issues at less than half the depth of the really deep South African mines, or so I've been told.

Eventually, even if you've still got economically extractable minerals (and don't forget you've got to haul 'em all the way up to the surface as well, which takes time and money), the stress of mining at depth makes mining effectively impossible, although new ground control techniques keep pushing that maximum depth out and out.

- What are the valuable things down there that make it worth all the digging?

Metals make the world go round. Copper, gold, coal, nickel, tin, diamonds, rare earths ... everything you consume, touch, use, look at, enjoy has some part that came from mining. It is fundamental to modern civilisation.

And as BigB notes, once you're into a mine, even if you're getting really deep, it's usually cheaper to keep going with that mine if geology allows than to close it down, find a new deposit, set up a new mine and related infrastructure, and start digging again.

Another issue is that mines are developed where the minerals are but these days, especially in mature mining areas such as the United States and Australia, the high grade and easy-to-find minerals have all been tapped out.

So that means new deposits are generally either deeper under cover or are lower grade and less economic, so it makes sense to keep going with good deposits as long as possible.
posted by jasperella at 9:47 PM on August 2, 2011 [1 favorite]


I went on a field trip to Kidd Creek during university and it was awesome! I think we went on a very similar tour. I am claustrophobic, but I was surprised how wide the stopes are, I never felt claustrophobic at all. I also remember it being really windy becaue of the ventilation, which helped.

The best part was driving around underground in the back of an open jeep - it was pitch black and bumpy and fast, and things kept hitting us on the head. With the huge hissing pneumatic doors, it was like a super-realistic Disney ride.

It was such a unique experience, highly recommended if you ever happen to be in Sudbury.
posted by piper4 at 10:52 PM on August 2, 2011


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