Rangersedge,
I just drained my pond down (I have a bottom drain) about 70". I did it over the course of several weeks using a 2" ball valve to control the flow. I have an 8" pipe through the dam. I may be overly cautious, but I was concerned about going too fast and having the saturated soils slide down with the decreasing water level. I did a fairly fast (.75"/Hr) draw down of about 18" a year ago and had a sandbar area that separates two sections erode when the water got down that far.
Don't know how big your pond is or how steep your banks are, but that 8" pipe is going to move a lot of water and with no means of throttling you may want to limit how far you drop the level.
I'm sure others can respond with experience, where I am supposing...
Good Luck; waiting for pictures.
