My folks used dynamite to fix a flooded basement.
The downstairs toilet would occasionally bubble sewage. We did a perk test out front where you pour some water in a hole and see how long it takes to drain. It didn't. A problem, because septic tanks are designed to spill into the drain field and seep into the earth. Otherwise, stuff backs up and heads to the basement toilet. Not the stuff you're looking for...
So a new system and a new front yard. It was Summer break and free labor was at hand; my Mom, Mike, me, our stepfather Joe and his other sons Bruce and Hugh.
We set to it. Shovels and picks and buckets. Trenches were dug in a modified palmate pattern. At the end of each day you couldn't tell Pharaoh from slave.
Two feet down, however, the ground was still impervious. A heavy rain could send it all right back up into our basement. The three foot level was the same.
Joe and my Mom consulted and came up with the big idea: dig a real deep hole at the low end and let all the, ahem, water drain to there. Hard pan couldn't go down forever.
The hole was about four foot a side and as it got deeper we built a gantry to winch up the buckets of muck.
Bucket after bucket... Thirty miserable feet later we were still in clay, shaky aluminum ladder to the bottom and each load heavier than the last. This boot-sucking crap had to end somewhere!
And then Joe thought: dynamite.
It would punch right through through the hard pan! Loosen it up, anyway. We had already broken one shovel.
Naturally we had a box of dynamite on hand. We wired a few sticks on the bottom of the hole and tossed down some branches and stuff to "deflect" the force. We pulled up the ladder and cleared the area. I was stationed on the road out front to stop any traffic. Joe checked on everyone, yelled Fire in the Hole! and threw the switch.
I was about forty feet away, watching for cars. There was a nice bang, somewhat muffled and dust fountained out of the hole. Then within a breath, the road convulsed and I was tossed to the ground.
Today you'd hear dozens of car alarms go off, but this was Suburbia in the Sixties and a quieter time (well, not on that particular day).
The blast had no appreciable impact on the clay. Just as smooth as we had left it but covered in debris. We wearily called it good and filled the well with loose dirt and gravel.
The basement toilet seemed to work okay for the next twenty years and then the sewer came to the neighborhood.