It's called day lighting , potholing or Hydro Vacing.
Most major area's have a company that does this either on their own or as part of an excavation company. I see the utilities around here using them more than backhoes now to open up their underground installed services.
One of the bigger companies in North America is called Badger Daylighting. Doing a search on Hydrovac brings up lots of companies.
I think that United Rentals also rents small units you can tow behind you but you have to find a place to dump the spoils as all the dirt/mud will not fit back into the hole.
