Pond Boss Forums POND CONSTRUCTION Building a dam 12 acre lake damage via flash flood

I am fortunate to say i still have a lake.
thanks to heavy clay/rock mix soil used on our dam.

While out of town, we recieved a very large amount of rain couple days ago. came back today and noticed my lake down 3 ft.

This corrigated metal culvert around 30", is connected to a larger horizontal culvert pipe.
the horizonatal pipe has been starting to rust out the past year.
We were in the process of designing a concrete spillway, but this happened 1st.

I have a emergency spillway, that worked. but the clay/dirt around this pipe must have gotten washed out from a leak.( im guessing) Now we are going to siphon down 4-5 ft in order to let this dry out so we can replan and give us some time in case it rains again.

Its still pretty unstable, so i place some plastic/rocks over where the water is entering to this hole. it stopped it from washing out even more, and is just draining at the moment.

if this drys out soon, could i pack more heavy clay into this to seal it off. ?

thanks
Don

That looks scary. You may want to take bags of concrete and make a dam in front of this pipe to keep the waves from lapping and taking more dirt out until you are able to fix this. Good luck.

Unfortunately I think you're either going to have to fill the pipe with concrete, drop the water and dig in another one, or drop the water and replace that one.

If left in place, I'd be constantly worried about the same thing happening, only worse.....

I took some more photos this morning.
after laying some plastic to keep it from being washed out. Tomorrow, i should have everything here to make a 8" siphon drain, we want to take this down another 4-5 feet.

It might take awhile to get it down. But it supposed to rain some more this week.

Thanks for the suggestions, everyone is appreiciated. I may use some of the suggested things
Thank you

I'm not an expert, but I agree with kenc

If that was my dam and it looked like that I would be actively
Repairing it not taking pics

If you get a significant amount of rain a small hole can become
A full breach pretty quick, and that's not a small hole

You did good so far, it could have been a lot worse. A siphon can move a lot more water than an overflow pipe like you have. You'll be suprised how much water it'll flow.

That is a beautiful pond. Hope you get it resolved soon.

looks like you have it some what under control, good luck...

Updates..

I had trouble finding 8" or larger pvc pipe quickly. So we went with 6" Sewer pipe(cheap thin wall)
we hooked it all up, and started it up, part of the pipe collapsed ( sucked together)
It was still siphoning, but maybe around 60% the flow.

Next day i orderd SDR-35 heavy pipe 6" and set it all up.
it worked great. both siphons were working.

I couldnt believe how much water those 2 6" siphons were taking out.

Lake is about 5ft down, and still going. we had a excavator guy come in that has experiance repairing dams and building them. we are going to plug the pipe with concrete, then compact clay with a mini excavator ( compactor attachment)

Next is the spillway design and estimates. I cant go back to these ,in the dam drain pipes.
between beavers,heavy rains and misc debris floating into it , its to risky...

i Will have pics up of my siphon system and how bad of shape the culvert pipe was it. It was a dissaster just waiting to happen.

Thanks for the updates! Glad that you averted a disaster. You running heavy wall on the suction side and thinwall on the discharge side?

I actually had the drain partially collapse on the back side.
it seems like it may have been an air pocket or somthing ?

there is 1 6" thin wall Sewer drain siphon and 1 6" Heavy.

we removed the riser and it just fell over. it was done very poorly. around the riser they used topsoil and it was not welded or fastened by any means to the horizontal pipe.

soon as we get some dry weather here, im gonna get this filled in properly.

thanks
Don

Whoo Boy! You're lucky that the whole dam didn't get cut thru!

I'm far from a expert but I was thinking the same thing.After reading how the culvert was put in along with other peoples horror stories chances are you avoided a BIG disaster.