Hey all! been trying to figure out how to fix my pond/dam and all my google searches seem to come here,so I figured i'd join and ask.

I bought a piece of property in 2014 that had an acre and a half pond on it of which 90% (including the dam) is on my property.
It was an old shallow pond that was build in the early 1900's with a mule and slip, and then the previous owner built up the levee/dam with a trackhoe. Unfortunately beavers and the poor initial levee construction the levee couldn't hold up and breached. When he built it he didn't pack it and had almost no slope to it being about 6ft wide at the top, around 20ft at the bottom and around 12ft tall (Both sides) and was mostly sand with a bit of topsoil.
I intend on taking the levee out completely and starting over, essentially pushing it all over to the swampy area on the back of the levee and building up on top.
It has an active spring(~1000gph) feeding it and it is in a natural valley. When it "dried" I attempted to walk across the pond bed and found that it has about 4ft of quicksand like smelly nasty muck. If I can't walk across it without sinking, I know I can't get my D5 (narrow gauge 93J) in there to push it for a while, although it has been 90-100+ for the last month. I've pumped it down and am keeping it pumped to allow the upper areas to dry. I think if I can ever find a clay bottom I can push it out,but how do I find bottom?
due to the geography, I really can't enlarge it to speak of, but plan on deepening it since it only had 2-4ft of water and tons of lily pads.The soil is a Sacul Sandy Loam according to the USGS Web soil survey

I say all that to ask this" How do I get started on this project without getting my dozer stuck and how do I do it right so I don't have to worry a bout it?
I figure I'll have to wait until september to go in there but am itching to get to work on it

thanks