It quit raining just long enough to go out and at least try it and see if it works, in 10 minutes I got 2 pennies , a quarter , a nail, a nickel and a 9 mm casing. I thought that wasnt bad for the first ten minutes in my front yard. On the way home I stopped at the local walmart and bought a garden trowel for .94 one of those little forks on a long prong I think its called a deweeder for the same price. In town today they had a semi tool sale so I went out there. They had a very cheap ice pick for .50 Then when I got home it wasnt raining and I went out armed with the ice pick and trowel. On the first sound I stuck the ice pick in the ground and bingo it stopped about an 1 1/2 inches , with the trowel I dug down and flipped out a pennies. Now I know from the experts that isnt much but for the first time in just trying it out I think I found the federal reserve bank myself. Cant wait for the rain to stop
So I dont know what you need to dig with really , but I think at first try I did pretty good with the ice pick