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posted by Snow on Thursday December 29 2016, @09:24PM   Printer-friendly
from the unnatural-disaster dept.

Shortly after the dam went into use, Nadhir al-Ansari, a consulting engineer, made an inspection for the Ministry of Water Resources. “I was shocked,” he told me. Sinkholes were forming around the dam, and pools of water had begun bubbling up on the banks downstream. “You could see the cracks, you could see the fractures underground,” Ansari said. The water travelling around the dam, known as “seepage,” is normal in limited amounts, but the gypsum makes it potentially catastrophic. “When I took my report back to Baghdad, the chief engineer was furious—he was more than furious. But it was too late. The dam was already finished.”

The dam was built in an area that contains a high amount of water-soluble gypsum. The pressure from the dam's water is causing this gypsum to dissolve, leaving behind voids in the ground beneath the dam. Workers and engineers have been working to fill the voids with 'grout' - a cement mixture:

Inside the gallery, the engineers are engaged in what amounts to an endless struggle against nature. Using antiquated pumps as large as truck engines, they drive enormous quantities of liquid cement into the earth. Since the dam opened, in 1984, engineers working in the gallery have pumped close to a hundred thousand tons of grout—an average of ten tons a day—into the voids below.

[...]When ISIS fighters took the dam, in 2014, they drove away the overwhelming majority of the dam’s workers, and also captured the main grout-manufacturing plant in Mosul. Much of the dam’s equipment was destroyed, some by ISIS and some by American air strikes. The grouting came to a standstill—but the passage of water underneath the dam did not.

http://www.newyorker.com/magazine/2017/01/02/a-bigger-problem-than-isis

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  • (Score: 3, Interesting) by zocalo on Friday December 30 2016, @11:06AM

    by zocalo (302) on Friday December 30 2016, @11:06AM (#447364)
    Yeah, I got that part, and the history aspect was interesting in both articles too. AFAICT though they appear to be maintaining the reservior more or less at capacity, which is probably necessary for efficiency of the power generation role (longer drop for the water, more energy through the turbines), but not so much for irrigation which I suspect could still be sufficient at much lower levels. If they can drop the level by (say) 50% and still maintain the necessary supplies for agriculture and consumption, but lose the ability to supply electrical power to Daesh held Mosul, then why not? A lower level would also reduce the pressure on the gypsum base, making maintenance less of an uphill battle too, and might even enable at least part of a controlled emergency release if a failure were deemed imminent, reducing the impact further. Or maybe the have dropped the level, and the article doesn't cover that detail.

    The only theory I have is that they fill the reservior during the spring melt, and then more or less drain it completely over the course of the summer, and keeping in mind that you need to maintain a base level as well, or the water becomes unfit for consumption, which might mean they rely on the maximum capacity each year. That's a pretty important detail if so, so it seems odd that it's not actually contained within the article, as to would be the fact that if that were the case then late summer/autumn, when the water level would be at its annual low, would also make a major annual maintenance window. The article seems well researched and written, but it also seems to have so pretty major omissions they should have been able to close, and it's that which is making me question whether they might be giving it a bit of a slant.
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