DANG near blew the porch off the side of me house... :0*/
'Way back my dad was the reeve of the R.M. A job he took upon himself [as far as I knew he had no official training] was to dynamite beaver dams where they were flooding the R.M.'s roads. He'd leave one of us kids at each edge of the valley, +/- 3/8 of a mile away. He punched a hole in the dam with a fence post and put the charge [I think it was about 6 sticks in a juice can] into the hole. A kid at the nearby truck would honk to signal us on top to stop traffic. Wait a minute or so, until he was sure no traffic was coming down the hill, then he'd lite the fuse, make his way to the truck and drive out of the valley. The resulting hole in the dam was probably +15 feet wide and I'd guess 6 or 8 feet deep.... very impressive in our impressionable minds! The beaver would have it rebuilt in 2 or 3 days, so the process got repeated every week or two.
He was also allowed [less red tape back then] to purchase dynamite for personal use, so he got some to blast big rocks that were interfering with field work. One such rock was out in the middle of the quarter, but there was an old rickety wooden granary, +/- 80 yards away. We dug a hole under one edge...I'm sure the charge was considerably less than the beaver dam ones... he covered the charge/hole with a rock probably 1'X1'X6" [ostensibly it would "force the blast downward"] ... and anyway, who were us kids to question?
We hustled to take cover (?) in the granary. When the dust settled, the "cover" rock was about 40 yards past the granary... and the big rock had jiggled a bit. With a bit more digging we were able to get it out with chains and a couple of tractors. Nuthin' to it when you know what yer doin'!!