Good move with Ronnie.
Here are a few helpful hints, now that you have decided your approach.
Budget 25% more than what you expect to spend, for a "safety net." In 30 years of doing this stuff, I have never found a situation where all pitfalls and pratfalls can be reasonably predicted, simply because some of the "problems" are buried or haven't been identified, yet. Budgeting another $2,000 minimizes the emotions of "surprises."
One acre of dirt, one foot deep, is 1,667 cubic yards of material. Otto has told me many, many times that with a bulldozer the equivalent of a Caterpillar D-6, he can move about 2,000 cubic yards per day, as long as the soil is dry. An excavator can move much more.
Where are you planning to put the excavated dirt? If you didn't discuss this with Ronnie, you should. Earthmovers almost always want to move the dirt the shortest distance possible. That may be he intends to pile it up nearby and build you a ski slope. You probably talked with him about it, but if not, you should.
Regarding the dam, what it sounds like to me is that he sees how major the dam renovation would be and has figured out that you guys can excavated and make the pond bigger by leaving the leaky dam virtually alone and allowing the "leak down" elevation to become the new "full" and improve the pond by deepening it.
If that's good with you, it will be good with him.
Last, I do think it's a good idea to go look at some of his finished projects so you can visualize something similar. Often, an earthmover's idea of "finished" isn't always your idea of "finished." Looking at some of his projects is educational and he shouldn't be offended. He should be proud to show off his work.
You are tactful, we can tell. Just tell him you want to look at some of his work so you can see what he does.
Thanks! I never thought of the ski slope!

What a great idea! Not sure how much use I would get out of it in Alabama but I am sure we can come up with something. Actually we have a portion of our property that is washed out and are planning to put the excess there if possible. Some of it will be used to sculpture the bank more and lessen the slope, it is quite steep now.
He has an excavator and a D-5. According to your figures on dirt removal, I think the 2 week time line is doable after the pond dries out. We are only going down 6-8'.
Yesterday Phil Carter who teaches the pond management course came over and found where the water is leaking out of the backside of the dam. The leak is about 10' long and you can actually see the water perking up through the soil. It was a bit hard to figure out at first because there is a natural wetland behind one section of the dam. Now that we know the approximate area of the leak we can try to identify it from the front once the pond is drained down.
Bob, thank you again for the advice.