I know I could hire a welder to lengthen this pipe but I'm wondering if a pvc solution might be doable. I want to raise the water level of my pond at least 2 feet-possibly 3. Anyone try this?

David in Oklahoma.

This is the solution I have used, but it is not cheap.

https://www.agridrain.com/shop/c85/water...rol-structures/

The advantage is that you can raise the level gradually over years allowing emergent plants to adapt.

To do this in one of our ponds i bought a rubber coupler (that overflow pipe is 8 inch cast iron) to connect the pipe to a piece of PVC. That short piece of PVC then slipped into a 22 degree PVC elbow ($95 delivered) and then a final piece of PVC was slipped into the top of the elbow cut to the length needed to raise the water to the desired level. I had a scrap piece of 8 inch schedule 40 PVC so i did not have to buy that. The coupler (bought on Amazon) and the elbow (bought from PVC Pipe Supplies.....google PVC 22 degree elbow in the appropriate diameter and that company will likely pop up) cost a total of about $120.

The beauty of the slip in elbow is that you can raise the water in the spring by just slipping the PVC into the top of the elbow (watertight with no glue needed) and then if you wish to kill/freeze some shore weeds in the winter just pull it back out and do a winter "drawdown".

Works great and not expensive. I could have purchased a cheaper coupler but decided to go with better quality. Your overflow pipe looks nearly horizontal so maybe a 45 degree elbow would be better. This is a very easy improvement to make. Nobody local carried the 8 inch PVC elbow i needed....not even the professional plumbing places.

That is a very, very cool device. Thanks for the link.

David

It looks in the pic like your pipe might be cut back at an angle on the downward side. If so, you would of course need to square it off somehow (sawzall) before adding a rubber coupling.

Bassmaster61, what you described is sort of what i had envisioned but wasn't sure whether or not my idea was sound. One thing that concerns me is that my steel pipe has a 1-2" "hood" covering a the top part of the opening (hard to describe. My understanding is this has something to do with reducing turbulence/air while draining. I have no engineering background and am not sure how important this is, and whether or not an "extension" pipe should have a similar opening. Thoughts?

Thank you for you input.

David

I would use a flashboard riser system like RAH linked to. That gives you the most flexibility and the easiest to use. If you go with a vertical tube/pipe, you will have to put an anti-vortex device on it.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=283820

FYI - I actually have a hood over both of my flashboard boxes to help with preventing a vortex in very big floods. This is not a cover for the box, but is above the box itself.

I wonder if my overflow doesn't get the "vortex" effect because it is only vertical....and not perfectly vertical....for about 1 foot? The pipe is slightly tilted out toward the pond and then the water hits that 22 degree elbow pretty quick before spilling into a pipe that is only slanted about 15 degrees and then through the dam. This is in a 60+ year old 1.6 acre pond and I suspect there is even one more elbow buried deep in the dam before it drains away.

Does the vortex only form for longer vertical drops? Clearly I am not an engineer. Although I am familiar with the vortex concept as I remember drinking some Miller Light out of their "vortex" bottle that allowed you to drink faster.

Other than that my vortex experience is limited. BM61

When a pipe goes down hill and is unobstructed, the water in the pipe begins to pull water when it fills up with water (like a siphon). When the increased water speed pulls water from the pond surface faster than it can flow back in, air is pulled into the pipe decreasing maximum flow. Blocking the path of the air with a "hood" or reducing the vortex with an anti-vortex device prevents this. If you watch a bathtub empty, you can see how a vortex sucks air down into a drain before it empties.

I did something similar to what you want to do this spring. My cast iron drain pipe sits in the water vertically and is 8" in diameter. I wanted to add a foot or two more and I used a 8" pvc section that I sanded and notched the bottom to fit inside the drain pipe and tapped it in with a mallet.

In your case, you might try getting a 90 degree pvc elbow and doing the same thing. It should work.