I have been reading the post on this forum for some time. First off, I would like to thank you for taking the time to post. I have learned a lot. I really had no intention of posting here. I thought I had a good handle on it. But, before I burn any more diesel and time, I would like your opinions.
I live in Wilson county TN. I knew I would hit rock as I have excavated in this area a lot. From the test holes I dug, I thought it would work. I hit rock where I expected. It was wider than I envisioned. I guess my question is, will a foot or 2 of good clay seal around it? I have a little sketch below to help you visualize the rock elevations. The big wide rock will be baseline for elevations.

Elevations
• Entrance run off is 4’ above baseline (big rock).
• The first rock step down pictured drops 6 to 8”.
• Planned shoreline / dam elevation was 2’ above baseline (big rock).
• Current soil grade at the base of the dam is 9’ below baseline (big rock).
• Rock elevation at the bottom of the dam core trench is 12’ below baseline (big rock). 3’+ clay dam coverage.
• I just dug test holes down the ravine. The rock was at least 3’ below current grade. I planned to bring that up anyway.

Proposed Fixes
• New shoreline 4’ above baseline (little less than entrance runoff.) I would be happy if it would hold at 2’ above rock.
• Peninsula
• Drastically reduce pond size.
• Scrap this project. I’m not sure I would be happy with that option. As stubborn as some say I am, I will probably try it anyway.

Your opinions are most appreciated.

Well I don't have an opinion or any help, but I do find it an interesting subject and hope someone like Otto can come along with some suggestions. At least my non-informative post will keep your thread from going off the main page before someone that can actually help sees it and comments.

Thank you Snrub. After getting over my initial over reaction, I think I have a solution. As long as I don't run out of clay, I think I'm good. Sometimes I have to just walk away and think things over.

By all means come back and let us know what you did. And then later let us know if it was successful.

You can mark this thread as one of your followed threads so you can locate it later. Otherwise your threads can become hard to find after quite a bit of time passes. Especially if you end up posting much. If you don't post much you can just click on your posts number and follow backwards till you find it. Just a tip to help you follow threads you are interested in.

I think 2 ft of good clay, properly compacted should do it. Of course, there are always a couple of small areas that just don't work out.

I hope Otto will chime in, way more experience, I know just enough about dam building to be dangerous, I think your biggest obstacle is do you have enough clean, rock free clay, available to you to actually get your 2ft + layer of clean, sealing, well packing clay to line or cover the rock with, if so I think it can be done.
If it were me, any rock exposed in the core trench I would clean off as best as I could and add copious amounts of bentonite.
I actually sealed off a little pond that was leaking in a similar situation, when digging down thru the dam the only water I found seeping was right down at the shelf rock layer. I cleaned the rock as best as I could and put a bunch of bentonite, plus a little more mixed into the dirt in the first several layers and packed it back full to the surface with the cleanest clay I had available and it seemed to work great, thats been 12 yrs ago and as far as I know its holding fine, the property was sold several years ago so I haven't had any feedback for a couple years but the original owner was a friend of mine and was tickled with he out come.

This is my initial incentive behind this project. See the videos below. It had rained the day before and the ground was saturated. This runoff was after a 2 hour light rain, no more than 3. The drainage area is not that large. I'm not really sure why there is so much runoff.

https://youtu.be/LmQzb6r7I7o
https://youtu.be/8nDvGA3t4VY