To end the current thought over the removal of material through the addition of vacuum to a waterjet soil dislodging system, here is a short segment that shows us uncovering some inert mines. As it was part of a Humanitarian Demining Effort we had to make the system as inexpensive and simple as possible.
The pump therefore is one that you can buy at the local hardware store – operating at about 2 gpm and 1,000 psi and we have used a simple Shop Vac to provide the suction. The rest of the parts also came from the store, apart from the very small fractional hp electric motors that we used to turn the head and traverse the head over the ground. The excavation unit was, as you can see, mounted on a camera tripod. The idea being that if the mine reacted then the part destroyed would be so simple and inexpensive that it could be replaced within a few minutes for relatively little money.
Video of a small unit being used to uncover inert mines and other objects.
Mines are relatively sensitive things and so we had to be sure that the very low thrusts that the jet would exert in disaggregating the soil would not set the mine off. This required a combination of pressure, jet size and rotation speed considerations. The effectiveness of the combination selected is shown by the pebble sticking out of the side of the excavation which is not disturbed, although with only a little finger pressure it could be lifted out of the side wall.
We would then cut the mine apart, through the fuze, using an abrasive laden jet and in another post I will show the pictures of how we cut detonators apart and other sensitive explosive-laden materials, without their reaction, as well as showing pictures of what happens when we got a waterjet to ignite explosive.
