I'm trying to dig a trench for the electrical cable for a shed/office I'm building in my back garden. This is about 7 m long and should be 0.5 m deep. My soil seems to be about 5 cm of soil/turf and then soil which is full of gravel, stones and building waste like bricks, etc. What is the best way to approach this?
I tried first just making cuts into the soil using a spade to make a narrow slot. That didn't work once I got to the stones.
I also tried using an SDS drill with a 600 mm long chisel bit, but that tends to jam in between the stones and gravel, so I spent a lot of time trying to dislodge it from the ground.
The third technique was with the pressure washer and wet vac, to blast away the soil and suck up the water and smaller stones. This seems to be doing something, but it is painstakingly slow. Since the slot is quite narrow it's pretty difficult to pull up the stones and gravel.
Is there some other piece of equipment I should consider using, or some other technique?
Best Answer
You got a bad roll of the dice. Very good ideas and attempts that would work in more normal soil conditions. The problem is, if you continue then you will likely undermine the soil because that small rock will fall into the hole from the sides. That will be very difficult to back fill properly and over time it will settle and form a slight ditch / depression.
At this point I think I would call it on the attempt to minimize the work and / effect on the yard and just dig a proper ditch. It could still be narrow-ish, the width of a shovel. This will give you the space you need to backfill in layers compacting as you go and in the end (years from now) it will pay off in spades.