I need to replace the drain pipe in a pond about 3/4 of an acre and I have a question about the new drain pipe. The old pipe is damaged beond repair and is at the bottom of 10ft embankment and I don't have the money at this time to dig the embankment up to repair the pipe. I don't have a need now or in the forseable future to dain the pond completly. I plan to abandon the old pipe and install a new pipe. I will dig a trench 3ft deep and put the pipe in the trench. I'll put a 5 or so degree slope on the pipe so it will be a straight run through the embankment. This will give 2ft of water above the pipe. I'll attach a riser pipe to the drain pipe. My question is what type/material of pipe should I use for the 6" drain pipe, PVC (Polyvinyl Cloride), Corrugated HDPE (high density polyetheylene) or cast iron. If I use corrugated pipe should it be single or double wall, if PVC should it be solid wall or foam core and what SCH 40, 80. I would prefer not to use cast iron unless its necessary. Is there any specification for the pipe to look for. The embankment is 12 - 15ft wide. The winters around here can get down to 5F for a week at a time but the oulet of the pipe will be under a 1ft of dirt. Also with this shallow of a depth does one need to use an antiseep collar. If it matters the old drain pipe was clay and lasted for 40-50 years. Its a long post but I am new to owning a pond and hope to get some advice from people who installed drain pipe in there pond. Any other advice would be appreciated.

Thanks in advance,