Whether or not you find my "computations" convincing, are you claiming that someone has found a way to "decomission" strip mines?

How about "decommissioning" the atmosphere?

The pH of the ocean is rapidly falling and coral reefs rapidly disappearing.   What are the plans for "decommissioning" the vanished reefs?

The Rhone glacier in Valais, Switzerland, is rapidly shrinking.   What are the plans for decommissioning the Rhone River, which originates from it?

If you are French, whether or not you know it, you are extremely lucky to have lots of nuclear plants.   Your country has the finest electrical generations system on the planet.

It is not true by the way that any coal plant, IGCC or otherwise, can be decommissioned at the same health standard applied to nuclear plants.   Simply because no one looks at the matter, doesn't mean that it is a non-issue.