Dam Failure - Any Suggestions?

[justinramani]

Good Afternoon,

As the title says - our dam is almost completely compromised. Its holding back about a 1 acre pond that is an average of 5-6 feed deep. The dam was installed before we purchased the property and it just couldnt handle all of the rain that we have had recently in NC. My wife and I dont really care for the pond, so my first idea is to drain the pond, grade down the dam and just install a culvert to deal with the spring that feeds the pond. As you can see from the picture its a pretty large washout that we are dealing with. Does anyone have any ideas that might help us get out of this situation? If the dam completely fails its going to wash out the only road that allows us access to our house.

Thanks in advance!!!

 

[AchingBack]

Quickly find a family of homeless beavers.

 

[Snobdds]

Go get some bentonite and patch that spill up. Then figure out a long term plan.

 

[dmccarty]

.... As you can see from the picture its a pretty large washout that we are dealing with. Does anyone have any ideas that might help us get out of this situation? If the dam completely fails its going to wash out the only road that allows us access to our house.

Thanks in advance!!!

Sounds like you need to drain the pond to get rid of at least some of the water to protect the dam and thus the road. You might have to rent a decent size pump and hoses to move the water out of the pond. I am not talking about some little itty bit pump, though that might work, but a pump on a trailer from a rental yard to get this done ASAP. The Corp of Engineers had to do this on a local lake where there was a drainage issue. They had to draw down the water on a part of the late where I think the drainage had clogged up and then build a new drainage.

Given that amount of rain we have had recently, and what we might get tonight, good luck!

Later,
Dan

 

[justinramani]

I just tried to locate a trailer mounted pump, but the closest I can find is over 60 miles away. Do yall think that the 4inch trash pump would work?

 

[newbury]

Good Afternoon,

As the title says - our dam is almost completely compromised. Its holding back about a 1 acre pond that is an average of 5-6 feed deep. The dam was installed before we purchased the property and it just couldnt handle all of the rain that we have had recently in NC. My wife and I dont really care for the pond, so my first idea is to drain the pond, grade down the dam and just install a culvert to deal with the spring that feeds the pond. As you can see from the picture its a pretty large washout that we are dealing with. Does anyone have any ideas that might help us get out of this situation? If the dam completely fails its going to wash out the only road that allows us access to our house.

Thanks in advance!!!

View attachment 483013

I'd cut a bigger hole in the dam to let it drain more before it failed catastrophically and washed out the road.

 

[Streetcar]

Start the 4" pump as soon as you can run it until pond is dry

Do not breach the dam as it will be hard to control the flow through the breach

 

[justinramani]

I thought about that. I'll go out tomorrow and dig out a trench for overflow. We wanted to let things settle down a little before we did that. Our neighbor upstream plugged his pond overflow, which is helping a little.

 

[Rustyiron]

If that's your road the water is running over, who ever built it did not put in (or size) the overflow properly. With a pond (and water) you need a plan "B" to handle too much flow for plan "A", your pipe.
Water should never flow over the berm/dam.

 

[oosik]

Doesn't your pond have an overflow? In any case a 4" trash pump at approximately 24K gallons/hour will take 65-70 hours of continuous pumping to completely drain your pond.

I'd be very careful about any type of overflow trench. Chances are the water will erode the trench and you might end up with a big gulley. Might be better to get some 6" plastic pipe & elbows and make a siphon over the dam. This will drain the pond without the chance of washing out the road.

 

[PILOON]

Don't know in your area but environment people can get very fussy about dams.
If you have any quantity of large rocks around I'd dump them downstream to control water flow as a minimum precaution.
In my area a person would be wide open to lawsuits for any downstream damage and the environment guys would force all kind of engineering studies prior to a repair.
If you do decide to drain be sure it is a controlled flow so as to prevent downstream damage.

 

[MossRoad]

How much of a drop is it from the pond to the other side of the road? You could siphon it out for cheap if its just a few inches lower. No pump needed.

 

[justinramani]

If that's your road the water is running over, who ever built it did not put in (or size) the overflow properly. With a pond (and water) you need a plan "B" to handle too much flow for plan "A", your pipe.
Water should never flow over the berm/dam.

No, this is the dam that is upstream of our road. If the dam goes - our road won't be able to handle the surge. I'm guessing that a 1 acre pond is about 3 million gallons of water....

 

[justinramani]

How much of a drop is it from the pond to the other side of the road? You could siphon it out for cheap if its just a few inches lower. No pump needed.

It ranges form about 2 feet in some areas to as much as 15+ feet in other areas.

 

[justinramani]

Doesn't your pond have an overflow? In any case a 4" trash pump at approximately 24K gallons/hour will take 65-70 hours of continuous pumping to completely drain your pond.

I'd be very careful about any type of overflow trench. Chances are the water will erode the trench and you might end up with a big gulley. Might be better to get some 6" plastic pipe & elbows and make a siphon over the dam. This will drain the pond without the chance of washing out the road.

I saw a video showing people using the 4 inch black pipe to create a siphon. Will that work too?

 

[MossRoad]

As long as there is just a slight drop in elevation the siphon will work. The more drop, the faster it'll run.

There's lots of videos about siphons and just how fast they work.

Try and get the outlet as far below the height of the pond surface as possible. As long as you don't have to go over a hill that's more than about 30' high, it will work if there's only an tiny difference(like even a fraction of an inch) from the surface of the water being drained to the opening of the outlet tube (the height has something to do with the barometric height of the liquid... if it gets too high, gas bubbles get pulled out of the liquid, form a bubble in the high spot in the pipe and break the siphon effect).

 

[roadhunter]

Start siphoning the pond off to lower the level and install Rip rap/cloth on other side of the road below a large culvert(s) that crosses under the road should be the first project IMO. You should be able to use collapsible pipe for siphoning. I've had them siphon after turning pumps off on many occasions. Withe the drainage system in place you could dump more water with additional hoses or a rental trash pump. Once the water in the pond is lowered you can install a proper overflow device of your choice and repair the dam. Then when you are finished you should be able to control the water level as well as protect your road.

 

[hosspuller]

I have a dam too. Your overflow is missing or has been blocked. I also say get a siphon going Now to reduce pressure on the dam. Do not dig a trench. You'll not have any control. 4 inch pipe will flow water but remember the area of a pipe increases by the square of the diameter. A 6 inch pipe has 28 inches of area while a 4 inch pipe has only 12.5 of area. A 10 inch pipe has 78 inches of area. Two 4 inch pipes still doesn't equal a single 6 inch pipe.

A simple siphon can be built using a plug, a length of flex pipe. lay the flex pipe over the dam. Plug the lower end. Fill the pipe with water and hold the uphill end under the surface. as deep as you want the level to be without sucking debris. When you remove the plug on the lower end, water will flow. any time you wish to stop the siphon just raise the suction end to the air. You won't be able to get a plug into the lower end against the water flow.

 

[Streetcar]

Start siphoning the pond off to lower the level and install Rip rap/cloth on other side of the road below a large culvert(s) that crosses under the road should be the first project IMO. You should be able to use collapsible pipe for siphoning. I've had them siphon after turning pumps off on many occasions. Withe the drainage system in place you could dump more water with additional hoses or a rental trash pump. Once the water in the pond is lowered you can install a proper overflow device of your choice and repair the dam. Then when you are finished you should be able to control the water level as well as protect your road.

The pond side of the siphon must resist the suction forces. The downhill side can be a collapsible pipe

 

[LD1]

No, this is the dam that is upstream of our road. If the dam goes - our road won't be able to handle the surge. I'm guessing that a 1 acre pond is about 3 million gallons of water....

An acre pond ~5' average depth is only about half the water you think. About 1.6M gallons.

A 100' roll of 6" solid drain tile is ~$100. That would flow alot of water. About what a 4" trash pump would but would consume no power.

If the water is close enough to where the discharge is gonna be, you can cut that 100' roll in half and have two siphons going. At ~25000 gph each, and two of them going....should be able to lower the water level about a foot every 6 hours.

The only issue with plastic tile is that it floats. SO you will need to do something to hold the end under the water.

I have seen several others suggest/ask, but never seen a response. What does the pond have currently, for overflow protection?