23 yards
32
about 71 cubic metres of gravel i think
That's not enough information. You need to know the width of the trench, and how much volume 1 ton of gravel is equivalent to.
You would need about 13 cu yards or about 15 tons.
Nor sure how pee gravel is packed, but you need enough for 64 cubic feet.
Approximately 24.7 cubic yards or 31.7 tons of gravel.
You will need 65.93 cubic yards or 84.6 tons of gravel.
You will need about 463 cubic yards (around 594 tons) of gravel for this area.
You'll need about 28.704 cubic yards (37 tons) of gravel.
You will need 20 cubic yards or 25.7 tons of gravel.
1
To fill it all the way to the top you'll need 18,502.4 gallons of water.