That is the combined hashrate of 15 workers, so, if I had to guess then that is a pretty decently sized farm (and I honestly hope they are able to use biogas to fuel it as that would be truly awesome).  30 to 34 Mh/s for one GTX 1070 and you can work up from there how many cards they are having to run to support the total hashrate.

I don't see why it would be "impossible", as the workers could actually be several different rigs.

Ok, maybe "decently sized" is an understatement, as that would be around 580 GTX 1070's.