Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Methods to Refill Existing Empty Pond?

On Feb. 22, our neighborhood community pond(4 acres in size?) emptied when the 13-year-old metal control gate at the bottom of the 42" riser rusted through and blew out. A dam engineer is suggesting a siphon system as a long term fix, but the neighborhood needs to to explore all options as we have a budget limited by the dues we have collected through the years. My main question: Is there a plastic pipe option with a control gate that would fit inside the existing 42" pipe like a sleeve so we would not have to bore into our dam to install a siphon system, or entirely tear out the existing riser? The pond is fed by underground springs so the water source is there and not a problem. Our problem would be to coffer dam away the water while fixing the system. So, my main question is: Does such a plastic sleeve system that would fit inside a 42" pipe exist? If it does, is it feasible to think a contractor could fit it together inside the existing metal pipe? If such a system is not possible, what is more feasible; to replace the existing riser system with aluminum, or is the siphon system simply the best solution all the way around? Thanks for any suggestions.

Welcome to PBF Clint,

I'm not a pro but I don't think you need to bore into you dam to install a siphon. My understanding is installing a siphon is probably one of the least invasive ways to install a drain.

Again, I'm not a pro. Hopefully, someone with more experience will chime in.

Bill D.

I just lined my old galvanized 6.25" well casing in a similar way by putting a 4" pvc liner in and grouting the annular space between them. It didnt even have to be dry to do it; the grout sets under water.

I sure would think about something similar here, but you've got a very different situation in many repects.

Can you provide a diagram of the whole system from inlet to outlet?

I don't see how to add a drawing here, but I can describe it: We had a 42" steel riser pipe with a trash catcher on top going down into what I think is a concrete pad (it's under spring water and mud). Attached to that riser was a control valve wheel controlling a very thin steel gate that must have been inside that concrete pad at the bottom of the riser (likely 15 feet under water). It blew out and we have the twisted, thin remains of the gate.

The riser rested in a 42" culvert running under the earth dam and emptying into a natural creek. From the outlet end of the pipe to the riser end is maybe 60 feet? The riser rested probably 25-30 feet "offshore." The control valve was never operated once the pond filled 13 years ago, and I doubt it ever could have been as the wheel was up in the air maybe 10 feet above the surface of the pond so even a man standing up in a boat could not reach it.

I forget without looking if there was a ladder on the riser, but still, a person would have to exit a boat to get onto the ladder.

The pond is naturally spring-fed for maybe 60 gallons a minute (pure guess), so when the pond was built 13 years ago, I guess when the pond was ready for filling, they adjusted the opening of the control gate until they saw that the lake was staying at an acceptable level (maybe 6 vertical feet from the top of the dam.

The level of the pond never changed in any heavy rain and there is no flow of surface water into it; just the occasional flow from a grassed lot when there was a very heavy rain. Water never flowed into the trash catcher.

Another source told me that a plastic sleeve inside the metal riser would not work because concrete will not stick to the plastic, but I could wrap it in roofing tar paper and the concrete may stick to that. One contractor we are talking to says a siphon system would have to be bored into the pond.

I haven't seen any designs on anything. We are waiting for a young, skinny guy to crawl into the culvert with a strong flashlight, yardstick, and cell camera to get a good look at where the water is coming into the culvert now in order to assess if the culvert and riser is anywhere close to a clean break.

Ideally, I guess we would like to use the siphon system so there is nothing mechanical to fail in the future, but one contractor is talking about boring to install it. I don't know enough to question why we can't use the existing culvert to run through the dam. If someone here can explain why we can't, I would appreciate it.

Your jurisdiction may have various things to say on water level control .. mainly to be engineered for different height inlets with different flow rates. I don't know a lot about that stuff, but I see it when I see these large risers with large pipes.

It seems like a control valve is unnecessary, simplifying things a bit.

It's a bit unclear to me how exactly the riser is connected to the lateral pipe and where the failure was. This is pretty important.

Did I miss something here... how do you know the pond is empty? How big is pond? Why do you need to rid of what's left? Is there unwanted species ?

I am not sure how the riser is connected to the lateral pipe as it is under water. We are waiting for a young volunteer to crawl into the 43" pipe to video, photograph and measure the break. From the outside, there is mud and a pool of water that means we can't get a good look from the outside so we are going to see what we can see from the outside. I imagine it is pretty simple; a control gate welded into the bottom of the riser that was inserted into the lateral pipe that looks like it rests in a concrete box (now under mud too). Crawling into the pipe is "easy"; there is about a 4" across stream of spring water flowing through it all the time that the volunteer will straddle.

As to how we know the pond is empty in the other comment, we can see it. It is a community pond that I think the developers dug in order to do something with the continuously flowing underground springs. The 13-year old flow control gate simply rusted through and failed, emptying the pond. There were no invasive species of fish or plants.

I keep hearing that a siphon system is the best replacement. Can you put that in the lateral pipe at the bottom of the pond rather than drilling into the pond wall?

Take lots of pictures!

I wouldn't presume a siphon is the best option even when starting from scratch. They have their advantages, but disadvantages too. Contractors around here (raleigh, nc) don't like them at all.

You're not starting from scratch however, and removing or abandoning your current system is no easy task. I think you're right to be looking for a simpler fix.

In studying various drainage systems for my own pond, this is the best drawing and explanation of a bottom withdrawal/siphon system I have found on the interwebs:

http://www.georgialandsales.com/pdf/PondSiphonSystem.pdf

This would probably be the least invasive to the dam as it does not need to penetrate much of the core. Just shallow digging with a backhoe. Install it then plug the existing drain pipe with concrete? Perhaps no need for a coffer dam.

Thanks everyone for the replies. To update, we've decided to go with the siphon system the engineer we've consulted and at least two of the contractors we will contact have suggested. The young, skinny guy who volunteered to crawl into the lateral pipe is relieved he won't have to take photos of the damage to the old system. The engineer convinced us that a sleeve wasn't practical, and replacing the current mechanical system would fail at some point in the future. I've noted that some contractors don't like the siphon. We will fill the old system with concrete and hope the siphon system works the way it should. I appreciate the help with ideas!

My recommendation is this:
Don't let budget get in the way of doing this "right"...whatever that is. Anything less is likely a bandaid.
When that water control system was designed, there was a reason. If you can contact the original designer of the system, or your engineer understands it, I'd look at the best way to fix it.
A siphon might work, but will it handle the volume of water that comes during high flow?
Will the elevation of water during a flood event compromise the lowest point of the dam? If any of this is a concern, I'd sure look at other options. If you use an engineer and follow his recommendations, and use a reputable, bonded contractor, you have confidence...and recourse.