I asked because a less experienced individual was quoting me with a jd450y rental. Not too keen on his pond building skills. I will probably pass.
If you try to build and compact with a dozer alone the dam will probably leak, at least for a couple of years, even if it's pure clay.
At least have heavy wheeled equipment, such as a large heavy tractor with loaded bucket to drive over and compact each layer. That's what we did with my second pond, and its dam seeped a little but stopped leaking after about 10 months.
Mine's about the size and depth the OP mentioned, and it took three days with a Case 650K dozer and large Case backhoe, with the dozer operating full time and the backhoe as needed. Two operators.
We used the backhoe also to distribute the stockpiled topsoil to the back of the dam at the end, then spread it with the dozer. It's been two years now, and the backside of the dam has great grass, thanks to the deep topsoil layer.
