Or am I just overthinking this? It seems many people with embankment ponds simply create a dam and flood native ground leaving plenty of brush/timber/native topsoil that is not removed and/or compacted underneath.
Thanks for any help.
This may work perfectly well in some areas. Around this part of Ohio, we have many different soils/dirt types. There are vast areas with sand and gravel deposits, some areas with nothing but solid clay, and then areas with everything in between. A good pond guy will know what you have and what is best. However, it's good for you to know this to, so somebody doesn't give you a line of bull and end up with troubles later.
Hello,
What I don't comprehend is; by leaving some standing timber at the bottom or a few islands... Is that a potential source of leakage (through the roots if they penetrate your clay layer into a more porous soil)?
Yes, depending on soil type. Usually the safest bet is to remove and add structure after compacted. You don't want leaking troubles at the very bottom of the pond.
Also when leaving an island (with trees) either just above or below final water level... Should the clay pond bottom be disked into the island topsoil and compacted to prevent sandwiching layers or leaking at that point(like the process to add soil to the top of a dam)?
You would want the pond bottom to be clay and have it come up to the shoreline of the island. This would seal off any leaks that may be under the island, but the surface of the island has to be above water. If the the water goes above the island, I would think you want to seal the whole island surface, then add whatever(topsoil, plants, etc) to the island after sealing.
