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 Post subject: Gold Mine Leak
PostPosted: Sun Aug 09, 2015 10:34 pm 
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http://www.huffingtonpost.com/huff-wires/20150807/apfn-us--mine-waste-leak/

So, in spite of my lack of confidence in government agencies (not helped by the fact that EPA workers accidentally caused the release), I'm inclined to think that the water entering my municipal water system will be checked thoroughly and so I have nothing to worry about. I'm also thinking that the plume will pass by and become diluted quickly enough to make it unlikely to have any effect on ground water used for private wells and irrigation. Direct irrigation from the river (while the plume is present) might be another story though. What do you think Set?

So, a general question: Does it make sense to even attempt to remediate the polluted water from these old mines? More water (from natural sources) will continue to pass through the mine, and fill it up if it is blocked again. This would simply lead to further remediation/accidental releases in the future, as opposed to a steady trickle that gets quickly diluted. I suppose if you plug it up real good, mineral laden water will form crystals and over millenia create new veins of commercial deposits in the old mine tunnels, This would probably be a good thing I guess.


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 Post subject: Re: Gold Mine Leak
PostPosted: Mon Aug 10, 2015 5:47 pm 
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barisax wrote:
http://www.huffingtonpost.com/huff-wires/20150807/apfn-us--mine-waste-leak/

So, in spite of my lack of confidence in government agencies (not helped by the fact that EPA workers accidentally caused the release),


EPA contractors. Actual EPA employees are accountants, lawyers, and now and then a scientist. All remedial work is contracted out.

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I'm inclined to think that the water entering my municipal water system will be checked thoroughly and so I have nothing to worry about.


There's a list of potential contaminants public drinking water suppliers are required to test:

http://water.epa.gov/drink/contaminants/

They're also required to publish the test results, usually done by Web site nowadays.

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I'm also thinking that the plume will pass by and become diluted quickly enough to make it unlikely to have any effect on ground water used for private wells and irrigation. Direct irrigation from the river (while the plume is present) might be another story though. What do you think Set?


The contaminants of concern are heavy metals. I'd SWAG that most are present as particulates rather than dissolved, which would mean that filtration (including natural filtration through an aquifer) would take them out. I don't know if the rivers affected are losing or gaining (hydrologic term - a "losing" stream loses water to groundwater; i.e., it flows out of the stream bed into aquifers. A "gaining" stream has groundwater flowing into it). Given the climate, I'd guess they're gaining in the mountains and losing further downstream.

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So, a general question: Does it make sense to even attempt to remediate the polluted water from these old mines?


This has been an environmental dilemma for some time.

Metal mining generally works by (1) finding an ore deposit; (2) digging out the ore; (3) breaking it into itty-bitty pieces; (4) extracting the metal you're interested in by mechanical or chemical means.

Because of the way they're generated, heavy metal ores are usually sulfur compounds. (Gold, of course, usually isn't combined with anything but the surrounding rock is still usually sulfides so gold mining is still extracting a lot of sulfide ore.). When exposed to air and water, sulfides generate sulfur dioxide, which ends up as sulfuric acid. This happens naturally all the time; "gold rush" era miners went for the already oxidized ore at the top of a deposit. The EPA is not allowed to remediate anything natural; thus when investigating supposed water contamination from mining there would be considerable investigation to verify that there was man-made source. EPA contractors interview "old timers" in the area and ask (for example) "Did you ever catch fish in that stream?"; and look at historical geographic names (for example, is the stream in question named "Acid Creek" on old maps?).

Driving a mine into an ore outcrop is going to increase the amount of ore exposed to air somewhat; if natural water makes it into the mine it's going to come out acidic (there are exceptions, of course; ores around Leadville, Colorado were in carbonates and the mine drainages are alkaline). However, the amount of natural water - what percolates in from rainfall and snowmelt - coming out of most old mines is going to be minor; more than you would get from water washing over natural ore outcrops but still not very significant.

However, getting water out of working mines was often a major expense. One frequent solution was driving a tunnel deep under all the mines in an area - perhaps as a cooperative venture by several mine owners - and using it as a drain. The famous Argo Tunnel, visible from Idaho Springs Colorado as you pass by on I-70, was one of these. When the mines were abandoned, the unmaintained drainage tunnels could plug up until something happened to release accumulated water.

It's not clear from the media reports exactly what happened in this release. Some of the stories mention "holding ponds" but others imply the water was inside a mine. The repeated mentions of "sludge" suggests tailings holding ponds, but it could be the reports are wrong.

At any rate, here's what I could find looking for the history of the area and remedial efforts:

http://pubs.usgs.gov/pp/1651/downloads/ ... _chapF.pdf

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More water (from natural sources) will continue to pass through the mine, and fill it up if it is blocked again. This would simply lead to further remediation/accidental releases in the future, as opposed to a steady trickle that gets quickly diluted. I suppose if you plug it up real good, mineral laden water will form crystals and over millenia create new veins of commercial deposits in the old mine tunnels, This would probably be a good thing I guess.


Again, it isn't quite clear what was going on; I haven't had time to read every media report. It seems from the USGS link above that the plan for this particular mine - identified as the "Gold King" in the media - was "hydrologic controls" plus "active treatment". "Hydrologic controls" suggests (again, my SWAG) doing some contouring to keep mine tailings from washing into a creek; "active treatment" is presumably something to raise pH and maybe precipitate metals.

As a final note - as should be obvious from the water color - most of the stuff released is various iron oxides, hydroxides, and oxyhydroxides. Spectacular but harmless.


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 Post subject: Re: Gold Mine Leak
PostPosted: Mon Aug 10, 2015 11:36 pm 
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That pdf you posted reminds me that these "pristine" mountain streams aren't as pristine as people think they are. Come to think of it, that Argo mill tunnel water was flowing right into the river that goes through Golden Colorado...home of Coors brewing company... Still, it beats the Cuyahoga river.

Thanks for clarifying about the contractors. That was my assumption, but from what I know of the oil industry, the big operators usually shoulder the burden of their contractor's mistakes. I think it's funny how quickly people are jumping on the EPA for fault, and questioning their assessments of the magnitude of the release. Usually, when the EPA makes such assessments that are critical of industry, they are taken as gospel (and rebuttals from industry are met with skepticism).


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 Post subject: Re: Gold Mine Leak
PostPosted: Tue Aug 11, 2015 12:11 am 
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The Argo Tunnel collapsed sometime in the 1940s and was never repaired because all gold mining was suspended by the government during WWII as unessential. Now and then a "slug" of water comes out of the tunnel, presumably because some internal dam has failed. Routine drainage is handled by a treatment system. I have no idea if the treatment plant could handle another "slug" event but I assume capacity information is out there somewhere.


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 Post subject: Re: Gold Mine Leak
PostPosted: Tue Aug 11, 2015 12:49 pm 
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EPA press release. Apparently investigation team removed some collapsed rock that was holding up shoring that was holding back dammed water.

http://www2.epa.gov/region8/gold-king-m ... y-response


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 Post subject: Re: Gold Mine Leak
PostPosted: Tue Aug 11, 2015 5:43 pm 
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 Post subject: Re: Gold Mine Leak
PostPosted: Tue Aug 11, 2015 7:35 pm 
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Probably looks really pretty at sunset.


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 Post subject: Re: Gold Mine Leak
PostPosted: Tue Aug 11, 2015 10:56 pm 
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The river is a little murky with a slight mustard tint today. Not very dramatic anymore. I was out of town when things went down.

I did see a pickup drive down my street towing a small flatbed trailer completely packed with cases of bottled water, like it was the zombie apocalypse or something.

I'm good with light beer and coffee. The coffee goes through a filter anyways.


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 Post subject: Re: Gold Mine Leak
PostPosted: Wed Aug 12, 2015 1:03 am 
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I liked the kayakers.

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 Post subject: Re: Gold Mine Leak
PostPosted: Wed Aug 12, 2015 1:42 pm 
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A Facebook friend who's an environmental geologist in Montana informs me that in the trade an accident like this is called "rolling trout".


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