We have several tractors up to 80 HP with FEL's as well as a ten foot wheeled scraper and I wouldn't even try a project like this, we have had a dozer come in to do all of our ponds and install the overflow pipe. It is more complicated than you would think and even with professionals doing the work, we had two levies blow out during an extremely heavy rain a couple of months after being built and the guy came back and fixed them.
You might check with your local Soil Conservation Service extension office to see if you can get some help with the project.