I am looking at buying a piece of property to move my business to. It has a large ditch down one side. Under the frontage road is a 6 foot wide by 4 foot high sqaure drain. Fill dirt is not a problem, but I have no idea how much the pipe sections will be. I am thinking at least a 60 inch pipe, I don't know what the corp of engineers would require ethier ( concrete, plastic, metal). I would appreciate any comments on approx price of the pipes. The whole distance is about 150 feet, but I don't need all the space right now, so I may do about a 3rd at a time over a couple of years.