On an existing pond would you drain the pond down prior to doing this or just get wet and muddy putting it in?
Depending on what you rely on for water to fill the pond, it could be both.
While it wasn't too grass friendly, last pond I did was with a tri-axle dump truck and an excavator (track hoe). Excavator dug the rip=rap out of the dump truck and placed it on the pond bank, both in and out of the water, depending on what pond and the water level in that pond.
