Published: August 29th, 2012 at 10:10 pm ET
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Title: Hurricane Isaac’s Eye Wall Expected to Barrel ‘Right Over’ Louisiana Sinkhole
Source: ABC News
Author: Christina Ng
Date: Aug 29, 2012
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Greg Hancock, a professor of geology at the College of William and Mary, said it’s hard to predict how the hurricane could affect the sinkhole.
“The fact that we’re going to get more rain doesn’t necessarily mean that there will be a great collapse of the sinkhole,” Hancock told ABCNews.com today, but said it was possible that “getting additional water into the sidewalls of this sinkhole could lead to a collapse in the sidewalls.”
Hancock likened the situtation to building a sandcastle on the beach.
“The last thing we want is for the sand to be really wet,” he said. “The more water gets added to the sand, the less stable it is.”
“There’s no reason why this sinkhole shouldn’t continue to grow, but I don’t know if it’ll have anything to do with how much rain they get,” Hancock said. “I’d want to keep an eye on it, but I don’t think there’s a reason to think that there’s going to be significant growth to this associated with the hurricane.”
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Published: August 29th, 2012 at 10:10 pm ET
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sending...
The last I heard…it was
>>>"…really wet…<<<
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really really really wet!
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Oh..lol.!
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As of 3 AM local, there has still been only an inch of rain total at the sinkhole from Isaac. By comparison, areas in the Mississippi delta and near Biloxi have received over a foot of rain. New Orleans has received about eight inches.
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"The expanding sinkhole is now approximately 427 feet deep, less than 300 feet from the top of Texas Brine's salt cavern that stretches down another 2,800 feet in the Napoleonville Salt Dome. Officials say they expect the sinkhole to continue growing."
It is 727 approx. feet to the top of the salt cavern.
I seriously doubt rain water would reach the cavern.
http://www.examiner.com/article/louisiana-sinkhole-saltier-the-deeper-it-gets?cid=rss
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Heart, I find things too ambiguous to draw that reassurance about the rainwater, although you could well be right. I have no direct knowledge of what is going on but as a curious observer:
1. The water-filled hole is now 427 feet deep. It started out as wooded land. Where did the water come from? Was it there just under the surface all along, and if so, might there be more such water in the remaining 300 feet above the TB salt cavern – is there any reason to believe that 300 foot buffer is solid rock?
2. The salinity apparently increases with depth. This suggests that the bottom of the hole may be solid (but rapidly dissolving) salt, rather than rock. If so, the 300 foot buffer might well be shrinking.
3. TB's salt cavern could take various forms. I don't think we've been given details. One possible form is that it is surrounded on all sides by salt rather than rock, making it potentially soluble in any direction. "The authorities" talk about a "failed cavern", which could mean almost anything.
4. Rainwater could go wherever the existing sinkhole water could go, which is of course a matter of speculation, but somehow it has gone from 0 to 427 feet deep recently. Did water go "down" 427 feet (from what source?) or has a pre-existing water pocket just become visible? Is the depth still increasing? If so, why and how quickly?… on and on.
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1…umm..I'l have to look back..I believe caprock..limestone.between top of dome and surface.
The drilling was venting through the aquifer..so perhaps the water from the aquifer is entering the cavern(s).
2. I agree.
3.True..salt domes also have fault situations around them.
4. I think water… salt..and chems…are coming up.
Bubbles= methane.
My question… natural or stored?
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Thanks, Heart. Re 1 – I suppose even if it is solid rock, there may be old drilled shafts, capped or otherwise that water might find. (Can you tell I'm still obsessing on that Louisiana salt dome disaster from 1980?)
Re the methane, good question. I wonder if "they" actually know what is down there with any precision or if brute-force trial-and-error is the main methodology. No way to tell from my vantage-point, but based on "oopsies" of the past I don't think "they" are brain-surgeons. Drill, baby, drill. Oops. Cap, baby, cap.
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The 330' of caprock is quite fractured towards the the bottom, but does extend all the way to the top of the salt dome. It couldn't form much of an open, air-filled cave if that's what you're thinking. If anything, the fracture space would be filled with brine (heavier than fresh water). I would think the operator also had the well filled with brine before plugging it. Fresh water wouldn't normally run 'down' into either brine-filled space, so 'sinkhole' probably isn't the best term for what's happening here.
The 'sinkhole' is in the bayou – the water/mud level is about where it always is depending on the tide. The sinkhole looks more like liquifaction or cratering caused by brine gushing OUT of a fracture in the caprock or maybe the side of the salt dome.
Salt caverns are known to continue building pressure *after* they are sealed. Texas Brine seems to have sealed the well properly, but the cavern itself may have fractured. It was constructed based on older, inaccurate salt dome flank location. A Dec. 2010 seismic survey shows the cavern is much closer to the west flank than previously thought. Diagram on Pg. 31 of this 111 Pg. PDF:
http://ucmwww.dnr.state.la.us/ucmsearch/UCMRedir.aspx?url=http%3a%2f%2fdnrucm%2fucm%2fgroups%2fconservation%2fdocuments%2fooc%2f4284979.pdf
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