Reddit poster vaguenonetheless provided no details of this boot-cleaning contraption, but it's safe to say this is an industrial facility, not something a guy rigged up between his garden and the back door:

Being obsessed with boot-cleaning contraptions, I poked around on the internet to find the source, but couldn't. The closest thing I found was this walk-through Boot Star II cleaning machine:

Both of these machines seem designed more for hygienic purposes than blasting off mud or gore. Incredibly, one commenter on the original thread reveals the following:

"I saw a similar one of those on a platium/gold/silver mine some years ago, it was to recover 'precious metals' from the boots acquired on labs, foundry or other areas of the mine and originally was not provided to help the workers get clean shoes."

If that's true, I'm curious to see what the collection system looks like.