[Rockhounds] Mosul Dam on Shaky (well, soluble) Ground

[Margaret Malm]

Another example, although much smaller. -- In the SW corner of Utah, near
St. George, they built a dam, just above the Virgin River east of St.
George, to impound water and make a recreational lake (Quail Lake). Built in
a formation, and on a fault) with lots of Selenite. Oked by at least one
prominent local geologist. One cofferdam had been leaking about ever since
it had been built, as was obvious from the constant stream ov water running
down in to the Virgin. About 15 years ago or so, just before Christmas, the
cofferdam went out, sending a huge flood down into the Virgin river and on
downstream to St. George, where homes in a rather posh subdivision near the
river were flooded.  Did they learn their lesson?  No!! it was rebuilt --
Over many protests. Because St. George had just spent a million bucks to
build a water purification plant (to remove the gypsum from the water in the
reservoir to make it potable after having soaked up the gypsum for some
years.) They said that the oriinal dam just hadn't been built right. So
there it sits. They did put in a pump to dry up the streambed so the leak is
no longer obvious. But it is most likely still there. And they have just
finished greatly enlarging their water treatment plant.

Margaret

-----Original Message-----
From: rockhounds-bounces at lists.drizzle.com
[mailto:rockhounds-bounces at lists.drizzle.com] On Behalf Of Gary Brown
Sent: Tuesday, October 30, 2007 8:29 AM
To: 'Rockhounds at drizzle.com: A mailing list for rock and gem collectors'
Subject: [Rockhounds] Mosul Dam on Shaky (well, soluble) Ground

Didn't the engineers of the Mosul Dam in Iraq ever take geology?  They built
a big chunk of the beast on top of gypsum beds.  500,000 will drown if it
breaks.  It reminds me of a dam on the south eastern margin of the black
hills.  Yup.  Built over the Spearfish.

GcB

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