Just out of curiosity, why do you need a 2' or 3' drain? I would be willing to bet ten times the cost of the pipe you will never see it run full in your lifetime, I doubt you would ever see a 12 inch pipe copletely full. I used 6 inch PVC pipe for my overflow of less than an acre pond. In reality two 6" pipes will carry twice as much but if you doubled the diameter to 12 inches you can carry 4 times the water. Not to be critical but it seems you are spending a lot of extra cash for rain run off when you should really have adequate free board in your dam to carry a couple days rain anyway. Just my opinion, worth what you paid for it probably.
