Including a larger shot of the property to better explain the layout and what I have put together so far. I have house and the grey block is my workshop. We are on city water and I would supplement the pond if it got too low or too hot.
Great call on google maps, there are several decent sized ponds in the immediate area which is a good indicator.
The sandstone junk had the consistency of crushed concrete. The backhoe got through it surprisingly well. I didn’t get deep enough to get passed it, but the little hole did not retain water in last nights storm. That layer is basically a drain.
To the crease (green dotted line) from the high end of the back side of my property (top right corner) I have about 4 feet. The back of my house is about 6 feet higher than the lowest point. Unfortunately, there are no springs on the property.
I do plan on building the u-shaped dam you referenced. Great call out on the distance/depth… Im 25 feet off my property line and 10 foot of the fence I had put in (red line is prop boundary, purple is the fence). I think the contractor should be able to get through that sandstone layer, but who knows what lies beneath. Might have to push the fence back. The 1 foot of clay lining is a helpful reference point as well. I appreciate the response!