There is a truck mounted tool for excavation that uses pneumatic pressure in conjunction with suction to remove dirt from around gas pipelines and such. Anyone know the name of it, and if there are small versions to be rented?
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.
It involves a pressure washer and a vacuum truck like they use to clean street catch basins. They blast the heck out of the soil with the pressure washer and suck the dirt and water out with the vacuum.
Most are capable of both air pressure or water pressure. Greg, I tried the heavy duty shop vac method, it works, but very slowly. I am trying to remove several yards of dirt from a tight crawlspace (my own) so I can fit under there to do some work on the ah..er...plumbing. The dirt is mostly loose powder and some small rocks.
I think you are going to wind up doing the " bucket and shovel" method! I have used the shop vac once to do some minor excavation around an inground pool where there was a plumbing issue.. it worked, and took time , but then again it was a small hole..