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Monday, January 16, 2017

America's Mosul Dams

https://en.wikipedia.org/wiki/
List_of_dams_and_reservoirs_in_United_States
Unless you are a dam engineer or dam(n) historian, dams are pretty boring news. In Norman Smith's classic treatise on dams - History of Dams - that received this great review when it came out decades ago, we learn that dams are some of the oldest structures on the planet dating back 5,000 years.

Dams are paradoxes, both loved and hated, serving as symbols of peace, and weapons of war. The latest news about the Mosul Dam, the fourth largest dam in the Middle East and located in Iraq, provides a good example. Like the vast majority of dams, the Mosul Dam had the typical mission of "controlling" water resources for agriculture and flood prevention.

The problem with Mosul Dam was the site geology got in the way of a good engineering project. The bedrock is gypsum, which is 100 times more soluble than limestone, leading to sinkholes and caves, not good things to try to pile a bunch of water near or store water on top of in large quantities. Of course, geotechnical engineers rarely let "geology" get in the way. All it will take is money and grout - and a lot of both.

But now with the human geography of the Middle East shifting with the advent of "populist" Springs, the control of nature, and the structures built to exert control, become targets to win. In this New Yorker article, Mosul Dam is considered a "bigger problem than ISIS". And this Al Jazeera article promotes the collapse of Mosul Dam would be "worse than a nuclear bomb." Even the Canadians are concerned as discussed in this CBC article and video where millions of Iraqis are at risk of flooding if the dam foundation were to collapse without its daily "injection" of the magic grout keeping the gypsum foundation from disintegrating.

America's love affair with dams has lead to something like 75,000 scattered across the US by the US Army Corps of Engineers, the federal Bureau of Reclamation, energy companies, and states that have the foresight to invest in water on their own like Wyoming.  As Norman Smith discussed, many of the proposed dams met their mission. Others, however, were not so lucky and failed, either by washing away, or were "leakers" meaning they never held water, or they barely held water. In at least one case outside the US, Smith describes the untimely demise of a dam design engineer when a king discovered that all of the water in his newly constructed dam leaked under the dam.

In the US, perhaps the most famous dam failure is the St. Francis Dam in California. The history and forensic engineering analysis of this catastrophic failure where a dam "tipped"over due to "hubric" overfilling is well documented by J. David Rogers in his incredible bookarticle, and presentation.

And then there are the dams like the Mosul Dam where the foundation of either the reservoir, dam abutments, or both, lead to the failure of the dam mission. Anchor Dam located in north central Wyoming is infamous for "leaking". I grew up in Wyoming and knew some of the contractors to the federal Bureau of Reclamation who constructed parts of the dam. Yet even with all of the information collected by the Bureau of Reclamation geologists and engineers, lots of myths and misinformation were shared with the public by prominent academic and government scientists. The misinformation lead to my paper to dispel some of the confusion regarding why the dam served as a money pit for so long (and continues to do so today).

One of my graduate students revisited the Tumalo Dam located in central Oregon. The dam was constructed over 100 years ago yet never held water due to sinkholes, presumably due to pirating of water by tubes and fractures in the volcanic rocks. Here is a video of someone from the area describing the turbid history. And here is the graduate student thesis exploring converting the "failed" dam site to managed aquifer storage and recovery.


But what about a dam that might rival Mosul Dam if it ultimately failed? Baker Dam in Washington state might fit this bill. Like the Tumalo Dam, the Baker Dam is almost 100 years old. And like the Tumalo Dam, much of the dam construction information was not documented, or in the case of Baker Dam, lost forever when a landslide destroyed the powerhouse where the documents were stored. Unlike Anchor and Tumalo dams, leakage occurred along the abutments following the initial filling of the reservoir, in part because no grout curtain was installed.

Seepage investigations indicate the possibility of the Baker Dam "failure". Concrete, Washington with a population of about 1,000, rests below Baker Dam, so while its failure would probably not rival a nuclear bomb in terms of lost life, the lost hydropower would likely be sorely missed in nearby Seattle.
* * * 
Law and order exist for the purpose of establishing justice and when they fail in this purpose they become the dangerously structured dams that block the flow of social progress. 
~Martin Luther King, Jr.

4 comments:

  1. Back in the 89s (I think) there was a lot of concern about the failure of the dam above Prineville. However, I seem to recall that the Corp was going to do some work to make it safer and more stable. Do you know anything more about its current status? Went through Prineville in Sept. Scary to see that town, landscape, and reservoir, and consider consequences of failure.

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    1. Update and correction of original reply

      See OREGON GEOLOGY, VOLUME 69, NUMBER 1, FALL 2009 that describes the "failing" Ochoco Dam located six miles east of the city of Prineville. Another oldie but goodie, the dam was completed in 1920 for irrigation and flood control as part of the United States Bureau of Reclamation (USBR) Crooked River Project.

      "Since its completion, the dam has suffered from persistent seepage problems beneath the right abutment (north side). Deteriorating site conditions since construction resulted in the temporary emptying of the reservoir in 1993. Water storage resumed in 1995 after modifications to increase bank stability and decrease seepage along the right abutment had been completed....Operational problems at the Ochoco Reservoir dam site are intimately linked to site geology. Quaternary landslide deposits line both margins of Ochoco Reservoir and form the foundations upon which the dam structure is built."

      "The construction site was chosen where landslide deposits formed the greatest topographic restriction in the valley. The left abutment (south side) of the dam is constructed upon rock-fall and debris flow deposits derived from the 3.56 Ma Basalt of Combs Flat of the Deschutes Formation. These deposits originate from over steepened, tension-cracked cliff-faces in the basalt that calve and topple or rotate listrically along fractured columnar joint margins. The right abutment of the dam is founded upon landslide deposits composed of intermixed rhyolite and tuffaceous siltstone derived from tension-cracked, southerly dipping, cliff-forming outcrops of the Rhyolite of Ochoco Reservoir and underlying sedimentary rocks interpreted as caldera moat-fill. Persistent seepage beneath the right abutment is linked to sinkholes developed in poorly sorted landslide deposits that have variable permeability and material strength."

      http://www.oregongeology.org/pubs/og/OGv69n01-CrookedRivercaldera.pdf

      Another example of geology getting in the way of a good engineering project!

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    2. Thanks so much! The emptying and "fixing" was earlier than I'd remembered. Was thinking about a decade ago.

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