Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Deteriorating overflow pipe

Hey folks, new guy here.
I just moved into a property with an awesome 6 acre pond, fed by at least 5+ underground springs. I've been told the pond was built back in the 1950's and the deep side with a hillside dam is around 50 ft deep.
There is an overflow pipe (18" (maybe 20?) galvanized) and it sits about 30-40ft from shore. I think it's a bit unique in that it runs straight down, and then come out 90 degrees outside of the dam wall. The overflow feeds a small creak, which hits the river about 1/4" mile away. The flow is always steady, probably a few gallons a second.
The issue is that I don't know the condition of the pipe, other than the top is rusting and and I can break small chips off with my fingers. I feel like I'm sitting on a time-bomb, a log (beavers) or loose boat floats into it from a strong wind.

I'm thinking an option may be to create a new overflow, built into a low corner of the dam, and possibly filling the old overflow pipe with concrete, but it's just an idea. I really need to a professional to get some advice, but not sure where to begin. One friend today suggested I need to talk to a civil engineer. Is that the best place to start?

Suggestions/Advice?

Thanks!

Welcome to the forum John
I also have a 6 acre pond in Texas tho. I only have a spillway with 2 24� corrugated plastic pipes dumping in to a forage pond. That has worked for me so far but not knowing how much flow you might have in a rain event I would not venture to give an opinion on it but the smart folks should be along to point you in the right direction. Again welcome.
I like your thinking but that�s me

I�d check with Solitude Lake managment and see if they can help or point you in the right direction.

JohnR...that "low spot" in the corner of your dam is, in all likelihood, your emergency spillway in case a huge rain event occurs that the primary drain can't handle. You will need to lower your pond level and build a coffer dam to get in and repair the old corrugated steel drain. Concrete is not going to seal the pipe, plus the chemicals in the concrete will speed rusting. Chances are high that water will flow outside and alongside the dam's through pipe, and eventually, it can cause total dam failure. BTW, lowering the water level for a while is almost always a benefit.


I sent you a PM

Thanks Rainman,

I had no idea what a 'coffer dam' was - but do now, thanks to YouTube . https://www.youtube.com/watch?v=tVHV5NVCGOU

Building a coffer dam would be an interesting project. Imagine i'd have to drain half the pond or more to get it to a level where the plates could be used to wall it off.

Another challenge is that the creek that was created from the drainage pipe - runs through a county park and into a river nearby. Not sure they would be keen on me flooding their park I could probably get their interest though if they could visualize what would happen if the pipe had a catastrophic failure and it all drained at once. The river could easily handle the overflow.

Attached a picture to give an idea of what it looks like. The left side is shallow, and you can tell i have some water-plant issues on that end, plus a spring-fed swamp that the beavers have created. Odd thing is that we didn't have hardly any plant growth issues until about 10-12 years ago, about the same time the beavers set up shop. The right side, I've been told, was 50 ft deep when it was built in the 50's. The other side of the dam is a pretty steep hillside that goes down into a wooded valley.

Looks like a beautiful place with a nice dock and LOTS of trees. Although trees on the dam is not recommended. Do you have any vehicle access to the dam?

You said the pipes are galvanized - are they the corrugated "culvert" style tubes? If so they have done well to last 50 years. Perhaps post photos of the water entrance and exit? And measure the height of the vertical pipe - inside and outside.

During a dry spell when there is no water going into the pipe at the surface, there should be none coming out below the pond.

Its good that a dam failure wouldn't be a risk to life/property. Its probably unlikely anyway. More likely to develop holes at the 90 degree joint and leak profusely until the pond is nearly gone. Best start a fund for what could be an expensive repair.

I'll try and get pictures of the pipes. Yes, they are corrugated.

We don't have a dry spell that affect the water levels, the pond stays level year round, unless we have a lot of rain and the drain gets slightly clogged, then it may rise a few inches. For the past 30 years, can't remember it being lower than maybe an inch, if that.
As I mentioned above, there are at least 4-5 underground springs, probably more. I only know of the ones we swim over

I'm in south-central VA.

#lovinpondlife

Stepped outside for a few minutes. Love working from home.


Skinny one, but not the only one today