Here is what the landscape architect came up with. I'm thinking about backing off from 12in to 8in pipe (it's only a 3/4 acre pond, after all) and going to PVC or other plastic pipe rather than corrugated metal. It also just seems like overkill for the type of project I'm doing. The elevation of the bottom of the storm drain 110ft away is 25.83ft and the water level will be at 28ft so I can't probably do much more than 1% grade on the outfall.
I need something, for sure, but the design as it stands now is adding about $10k to my pond construction cost.
