Wednesday, November 4, 2015

The West Lake Landfill fire, another case of exaggeration?

I was on my way to work this morning when a story came on the air about the West Lake Landfill fire and the risk of radioactive pollution release as a result.  The story itself was trying to explain the risks were not as high as some people would like to believe, but I wanted to do some reading of my own, as well as looking at the chemistry of the problem for myself.

The West Lake Landfill is a landfill outside of St. Louis, Missouri that is in the hole left over from a former limestone quarry.  It was then over time filled with the assorted detritus of humanity including, at some point in the 1970’s, some radioactive crud mixed with dirt left over from the cold war.

About five years ago an underground “fire” started.  I am using fire in quotes because what is actually occurring is that the methane being produced by the decomposition of the biologic materials in the landfill is breaking down into carbon monoxide and hydrogen in a chemical reaction at an elevated temperature.  If it was near the surface where it would have ready supplies of oxygen it could flare up, much as a compost pile can ignite if left untended, but thankfully, for the most part the fire is far underground.

First let’s take a look at the radioactive crud that someone decided to dump in the facility.  After the cold war and the absurd buildup of uranium based weapons hence, there was a large amount of radioactive material that was leftover in barrels which was sold at a public sale (no I am not making this up).  The material was in four grades, the least concentrated being leached barium sulfate cake.  The leached barium sulfate cake was considered to be below the uranium concentration that could be efficiently leached further to get anything of value out of, and was eventually mixed with clay and dumped on site.

So now we have a bunch of uranium dumped on site, OMG!  We are all going to die!

No, hold the phone.  The concentration of the uranium in the material after leaching and mixing with topsoil (not to mention that it was then mixed with the normal waste being dumped on-site), the concentration of uranium left in the soil is about 150ppm.  This is only an order of magnitude about the concentration commonly found in granite, and some granite commonly have uranium concentrations as high as ~50 ppm. 

Now let’s look at the fire.  First thing is that calling it a fire is not really an accurate description.  Calling this a fire is as accurate as saying your rusting car is on fire.  There is an oxidation reaction occurring within the heap that is converting methane into hydrogen and carbon monoxide.  The elevated temperatures that it is creating down in the heap are in the area that they would be hot to the touch, but not likely to seriously burn you.

The likely source of the fire is actually the methane gas extraction, as if they pull too much vacuum on the methane extraction it will pull an excess of oxygen down into the heap and start a reaction.

So what do we do!  We have to do something!

Well, not really.  Disturbing the mass will introduce more oxygen and give more fuel to the smolder.  Over time the pile will eventually run out of fuel.  If the heap is properly capped we can also prevent the oxygen it needs to keep “burning” from getting down into the pile. 

But what if the “fire” reaches the radioactive waste!  Won’t that turn St. Louis into the next Chernobyl?

No.  It won’t.

The concentrations of radioactive materials are too low, the fire is actually moving in the wrong direction, and even if it did reach the area where the radioactive waste is stored, the fact the waste was mixed with soil and is not just straight garbage would likely prevent the fire from penetrating into that part of the heap.

But what if the fire reaches the surface?  Could it then burn across the surface and raise all kinds of havoc?

It will raise all kinds of havoc, although mostly from the burning of the plastic cover as has happened in the past. 

But what can we do to prevent this?


Simple, don’t be such wasteful slobs.  Recycle, reuse, and don’t buy disposable shit from Wal-Mart.  Stop having hordes of not-very-bright children. 

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