Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Washed out spillway

Guys I need some advice on how to repair a washed out spillway. I recently purchased a house which has about a half an acre to an acre pond on it. I noticed several days ago that the spillway had water coming out from under the bottom of it in the back on the left side. A very minimal amount of water but I could also hear it running under the spillway so I knew it had hollowed out a canal under spillway. Well fast forward to today and now with all the rain we've had the water has washed out under the side of the spillway and the dam, where the concrete meets the dirt. Really it has washed under the concrete. It appears to have been a thin layer of concrete where it washed. I busted open the top of the concrete so I could see inside and survey the damage. It didn't wash out the actual spillway but the side of it where the it rolls up to the dirt. In the hole you can see where the spillway concrete is solid and deep. So basically you've got a concrete wall on one side and dirt wall on the other. Currently I'm draining the pond so I can work on the problem. My plan is to build a bulkhead on the side where the damage is and repour the concrete, I also threw some concrete chunks in the wash out area to try and stop it from eroding any worse until I can work on it. I guess my question is, is this the correct course of action to take or should I add clay? I've never owned a pond so I have no experience in this type of repair. I'm going to attach photos so yu guys can see what I'm talking about. Thanks to all whom reply.

Forgot to mention the size of the hole of about 2 foot deep by 2 foot wide.

I can't seem to figure out how to uplaod pictures. If someone could tell me how I'll upload them. thanks

nevermind I think it worked

Welcome to PondBoss BBK. Sorry for your troubles, but that is what brings a lot of us here to begin with.

At this point, it's hard saying what to do. There could be a lot of variables to this. You might take a few more pics of the situation, longer views, or more overall views. I think clay would be the way I would go about stopping it, even if it was for a temporary fix. You will have to pack it in tightly in every nook and cranny. Then work the rest up in packed layeys. I mean really pack it!! Do you know of any pond builders in your area to get a consult from?

Is this spillway the only place water exits the pond? Or do you have a regular overflow pipe?

Do you have much in the way of fish in the pond that is worth saving? It might be a good reason to start all over, if it comes to that. Not what you would hope for as new owner, but it's not the end of the world either. Could give you an excuse to get the pond EXACTLY the way you want it.

You are taking the right first step in lowering the level or draining. You're close to losing the whole works. While working on this, you might consider installing a siphon system in a hurry. Get the pressure off so you can determine the best solution.

Thanks for the replies guys. This spillway is the only place in the pond that the water exits. As far as the fish in the pond, it is currently stocked. I think I probably need a drain or overflow pipe in this pond somewhere but installing that will have to wait until I can get some extra dollars. At this point I'm only interested in trying to save what I have. This pond is over 10 years old and hasn't had any problems until now. I'm hoping that I'll be able to repair the spillway and atleast have a few years to save up some dollars before having to redo the entire drain system. If I can get the water level low enough to work on it wouldn't just filling the wash out with concrete stop the leak? I understand I'll need to make a bulkhead in front of the problem and dig a footing a back pour the concrete. I'll try and get more pictures...

That's why a regular overflow pipe would be good. For only ten years old, that's too soon to have this problem.



It might be cheaper that trying to repair this the proper way, and it will be better suited for the job. Could then fix this spillway up temporary and keep an eye on it when it is used in the worse of times. Then fix up later when funds allow.



Others will have to make suggestions here.

I have seen a few folks put heavy plastic sheeting or a liner down. It goes from down in the water and up and over the spillway, sealing way past the area where the soil meets the concrete and in between. It might be a temporary fix.



As Dave said, you want to get that water level pumped down and keep it down till you have it fixed. You are skirting close to a real disaster.

Thanks for the reply. In order to install a regualr overflow pipe wouldn't I have to completly drain my pond? How far down (deep) in the side of the dam should the pipe be buried. Wouldn't digging into the dam just further weaken an already stressed structure? Could someone point me towards some type of reading on installing a overflow pipe. Also as far as draining the pond basically I've been allowing it to slowly drain out of the area of the spillway which it washed out but once it gets down below that I'll need to drain more to allow the problem area to be exposed. I've seen you guys talking about a siphon system. Is there anything on this forum that shows a how to on that.


I'm thinking that getting the water level low enough to build a bulkhead and repair the spillway should fix the problem but I'm intrested in the overflow pipe and seeing if I can do both and have this thing fixed for good.

Forgive e if these questions are stupid but this is my first pond and or dealing with this type of situation. Thanks

Go this site and check out their diagrams of pipes. There is one for regular overflow and another for siphons. That will give you an idea of what they are and how they are built. In the archives, there is a post on installing a siphon drain. Its in the common Q&A section under siphons..... let me know if you cant find it.

http://www.ponddampiping.com/

Edit-Your questions are NOT stupid. Don't ever be afraid to ask.

Thanks that link and the Q&A was very helpful. I'm gonna build a make shift siphon and get this water level down low enough to fix this thing proper.

Any suggestions on how far away from the spillway I should install the overflow pipe?

If you go the pipe route you will have to live with lowering your full pool level from what it is today. Do you really want to do that? From just what you have shown us I would not be so quick to determine you need a pipe. Does your pond flow constantly over the concrete spillway due to a large water shed or spring or does it just flow out after a rain event and then level to the top of the concrete? What does the area look like below the dam i.e. the spillway outlet? How does the water once it flows out the spillway leave your property etc...? I personally would consider just cutting a cut off trench across the spillway and call out a concrete truck and fill it up along with the hole that has already developed assuming it not a bottomless pit under that area. You really don't need to drain the pond down any lower to fix this. It appears to me that the water just found a path under the concrete and it cut enough soil out over time then it finally collapsed. You’re going to have to fix the concrete even if you install a pipe.