Pond Boss Forums POND CONSTRUCTION Building a dam Outlet pipe question

We've been working to renovate an old pond...about an acre. We breached the dam and excavated the silt and are now ready to repair the dam and set a new outlet pipe.

I met with an engineer yesterday who suggested we not replace the outlet pipe in the trench we dug to drain the pond. He wants us to put a new pipe through the dam horizontally at the desired water height and then put in a 45 and run the pipe down the back of the dam above ground. He felt we'd have a much stronger dam and wouldn't have to deal with a seep collar. He's proposing a 10" PVC pipe.

I'm indifferent on the issue. It's not really an aesthetic issue where it sits, so that's not a problem. I would worry a little about ice, but maybe that's not a big deal. Just haven't seen many ponds done this way.

Is this a bad idea?

I like the ability to drain or lower water levels a pipe thru the dam gives you.
You wouldn't have had to breach the dam if one had been there before.
If done properly it won't be a problem.

What he's referring to is siphon system I believe. I think they're great. If you do a search for threads about siphons you'll find plenty of information about it.

Good luck!

The idea is not bad. Any time there is a way to make a dam stronger-safer it has to be considered. You just about have to listen to the engineer he saw the site and probably got paid.

Otto

The size of the pipe should be relative to the size of your watershed.
It doesn't sound like you're describing a siphon, just a straight pipe thru the top of the dam @ water level & down the back.
Is the engineer signing off on the dam repair?

You're right, it's not a siphon, it's a straight outlet pipe. The engineer isn't "signing off" on the repair...just offering his advice.

You mentioned lowering the water level. What are the reasons for this? We have two ponds, one about an acre and the other about 1/2 acre. I'm thinking if I needed to lower the water for vegetation it wouldn't take too long to pump out a couple of feet. Hopefully if we do this renovation right, we're able to catch the sediment at the head of the pond where we can easily clean it later without draining the whole pond. Plus it drains off CRP land and shouldn't silt too bad at this point.

Having said all that, I really want to do this right the first time...not too interested in starting this process over in five years.

I would still think you would need a seep collar. If you live where a flood is possible the water level may exceed the height of the pipe and go through the dam around the pipe. Do you also have an emergency spillway that is higher than the pipe?

Have you considered a siphon? For a little more money I think you'd get a lot more value.

I agree with James; I would still want anti-seep collars.

I don't know guys, the pressure is just not there, at water level, to require a collar.
I suppose if you don't mind pumping it could serve the same purpose as a drain pipe.
I think though if I wasn't going to utilize a pipe for draining I would do as GW suggests & go with a siphon. It would serve the same purpose as your at level drain pipe except it would be removing bad water rather than your best water as your current setup would.

OK Ric and GW, I like the idea of a siphon. That really would hit two birds with one stone. I've scanned a few threads and think I get the basic idea. Could be a great solution.

Two questions. One, If my pond is going to be around 12' deep, how deep should the intake be...or rather, how far off the bottom so it isn't likely to get plugged? Two, I don't think my contractor has dealt with a siphon before...who is the best resource for making sure we do this right?

I think you could work with these folks: http://www.ponddampiping.com/

You could also probably figure out how to build one based on the threads and photos on the forum. It's really pretty simple in practice.

Treeplanter

GW is right you and your contractor can do this with the info off the forum. Actually you will enjoy doing the work and the magic of the siphon will be very interesting. JUST DON'T ASK WHO FIGURED IT OUT IN THE FIRST PLACE.

Otto

Since Otto asked, the siphon was invented in 1879 by Benito di Siphoni, the head of the Papal Air Force. It was originally used for relief tubes for the pilots of the Vatican's Hot Air Observation Balloons.

Glad I DIDN'T ask.

Treeplanter

I needed to get back with you before you get corrupted, We have a few people that will tell you a story and think its funny,(AND SOMETIMES THEY ARE)

The pipe needs to be 3or 4 feet off the bottom, you can also tie it down away from the bank pointed toward the middle of the pond.

As far help you can get hold of me almost any time at
940-736-5333 cell
or 800-882-3478 home office

I will be glad to walk you or your contractor threw the process.

Otto

Now THAT'S friendly!

Otto,

Wow, that's above and beyond. I really appreciate the offer. We'll give it a go and will call you if we run into problems.

This forum is an outstanding resource...thanks for making it possible.

Couldn't have said it better myself.

A siphon will be a lot cheaper for you, too. You should be able to use 4" pipe rather than 10".

Siphons are cool to watch, but keep away from the business end. They can be dangerous.