River Levee Goes Boom

Some domestic ‘spolodie:

[youtube=http://www.youtube.com/watch?v=hZErCTZS0Nk]

Last night, the Corps of Engineers set off a chain of charges on a levee retaining the Mississippi River at Bird’s Point, Missouri.  This activated long standing flood control measures which allow waters to flow down a “flood way” towards the town of New Madrid, Missouri.  Sort of a “give the river more room and it won’t flood as bad” technique.

Word is houses some twenty to twenty-five miles away, including Hickman, Kentucky, were rattled by the blast.

More here.

7 thoughts on “River Levee Goes Boom”

  1. The NBC affiliate in Paducah, Ky (WPSD) mentioned feeling (rattled windows) the blast at their TV studio. My rough calculation puts it about 30 miles from the blast site.

  2. Earth moving explosives tend to be lower velocity explosives, designed more to “push” than “cut”, for instance, ANFO and similar charges. That lower rate of burn produces a lower frequency “boom” that travels further.

  3. Would the water saturated soil prevalent across the region affect how far the shock wave traveled?

    1. I honestly don’t know. I’m an infantryman, not a demolitions expert. Generally, I’d suspect it would, as denser materials would transmit the wave further, but that’s just a WAG.

  4. Brad, as an Engineer (Civil Engineer and professional Engineer) waterlogged soil is actually less dense than dry soil. Specific Gravity (SG) is a relative density and usually is based on water which has a specific gravity of 1 (there are other systems for lighter materials but they are not seen very often). Most soil has a SG of 2.5-3. Waterlogged soil, therefore will be have a composite SG of less than that of dry soil because the water tends to push soil particles apart.

    Dry soil tends to transmit the shock further than waterlogged soil as the water is far more elastic and tends to cushion the shock somewhat. Water will not transmit the shock nearly as far as rock or soil. I’ve been around when fairly light charges were set off when blasting rock that I felt strongly, and for breaching charges for a small dam, at about the same distance, when I did not feel it at all.

    I don’t have my blaster’s manual handy, and my memory is rusty on military grade explosives, but as I recall C-4 has a burn rate of around 8km per second, and ANFO is some where around 5-6km per second. From a blasting view point, the difference in effect is very small as the distances involved are also very small. If the holes are about 30′ deep for example, the burn will take about 1.1 milliseconds with C-4, and 1.8 milliseconds with ANFO (at 5km/second). The reason ANFO is used so much for blasting is it is cheap and easily made onsite (most commercial blasters have a manufacturer’s license because ANFO is mixed in the truck on site and is dropped in the hole as it’s made). There are more esoteric explosives that have applications where ANFO is not suitable (such as wet conditions). ANFO was probably not used to blow the levees.

    While from a blastign standpoint there isn’t much difference between C-4 and ANFO, there is a massive difference between ANFO and Black Powder, which is used on occasion for blasting. I’d have to locate my Blaster’s Manual to go into the details as I can’t remember the applications where Black Powder is preferable.

    As I said, I’m rusty on my burn rates so don’t my feet to the fire on that. The magnitudes should be fairly close, however.

    1. This should shed some light on the subject.

      “Army Corps crews by Wednesday were laying the groundwork for the explosives, a liquid mix of sodium perchlorate — often used to make ammunition — and aluminum powder. Crews then pump the slurry into pipes embedded into the levee in 1,000-foot lengths — each separated by 60-foot gaps — and accessible through manhole-like holes known as “fuse plugs” that are cut into the embankment, said Jim Lloyd, the corps’ operations leader in Memphis.

      The corps would use blasting caps with C-4 plastic explosives to set off the slurry, fracturing the levee’s top end enough that it would weaken, allowing the river to bust through it.”

      I pulled that out of this article: http://www.chicagobreakingnews.com/news/local/chibrknews-army-corps-prepares-to-blast-levee-to-save-cairo-20110428,0,7697808.story

    2. Trevor, that’s consistent with stuff I remember. Sodium perchlorate/AL slurries have a pretty high yield and is cheaper than other water resistant explosives. It’s harder to set off, though, thus the C-4 booster charges. ANFO is good stuff because it’s easy to make, and easy to set off as it is cap sensitive itself.

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