It depends...
Here we have shale type ledge and water actually stays on top of it because it does not drain down. I have a
hay field that has a lot of ledge in it, and when we go from the crest of one ledge to the other...about 200 feet apart, the trucks make ruts even in the dead of summer! The reason is the water just lies there. If there is a drought, it will dry up naturally, but in a regular year, it just pools.
I do a lot of
land clearing and sometimes landowners throw a pond into a land clearing
project. Last year I had a project like that. The guy wanted a "water feature" about half way down an incredibly steep mountainside that was almost pure ledge. The original plan was to put in a single pond, but the grade was not working with me. The far side of the pond would have had to been 12 feet deep and solid ledge kept me at 3 feet! So in the end, I split the two ponds in half, and installed a high culvert with a gravel road between them, rocked and sloped for looks. This made two ponds, but kept the second pond from draining the first pond, backwards from where we wanted the outlet to flow.
So then I started digging the second pond. This was tough because the uphill side was steep, solid ledge and about 20 feet high. All I had was a 28 foot excavator so that was no good. I ended up down in the hole, and baling soil to the downhill (ish) side, and building it up, then going above that and baling the soil out again. I dislike moving the same dirt twice, but sometimes it must be done. But it was like you describe, on a steep hill, very rocky (boulders the size of a queen size bed), and lots of clay. I hit some springs which was shocking, but a few weeks ago I went back to see how the project had fared the winter, and the ponds looked good. They still need work, and I am not happy with one end of the second pond...it just looks unfinished, but at that point it was December, winter had set in, and the guy had spent
enough money. I'll go back eventually, but it was a good job and came out well enough.
.png)
1
