Pond Boss Forums POND CONSTRUCTION Building a dam Slump in Dam

I have a 1 ac. pond thats 4 years old, and its got a slump in the dam near the drain tube.

The dams is about 70 yards across and the slump is about 25 yards of that.

The spillway is on the other side of the dam and just by eying it, it looks like the slump is lower than the spillway.

The pond holds water to the bottom of the drain tube but it apears that the drain tube is sinking.

What do I need to do to repair the slump and raise the drain tube to the proper water level.
Thanks for your input.

Welcome to the most informative site on ponds around Kenny!

Sure sounds like a tube is leaking. Do you have pics by chance?

Look in the resource section and find Mike Otto. He can give you more info than anyone here.

Any repair inf I offer would probably lead to more trouble.

You'll get some good info very soon.

Thanks Rainman

Hi Kenny,welcome to the forum.I tend to agree with Rainman,in that you have a leaky pipe.Please give us more info...haw big and long is the pipe?Trees and or vegetation on dan etc.The experts will probably need more info.If you dont get it resolved post back and Ill give you some really dumb advice

Pipe is 6" steel with a steel collar at mid dam, 110' pipe run.
Dam is sloped 3-1 water side & 4-1 dry side, with dam height 4' above the water level and about 10'to 12' across the top. Soil is clay with a top coat of top soil and k33 grass over the entire dam. The dam was built in the middle of a dry summer and it took about 12 months to fill up. The only vegetation is grass and cattails.

Ruh Roh!

A pond being built in a dry summer has cost me $20K and counting in repairs. There is no way to compact clay that is either too dry or too wet. We had to drain the pond and then had 6 feet of new clay added to the face of the dam in 6" lifts. Our clay was so dry when the thing was built that AFTER adding 6 extra feet, the weight of the earthmovers had compacted the dam's height 5 feet below our starting point (the top of the original dam was never disturbed). Contact your local NRCS agent and ask him to come check the integrity of your dam and to recommend what needs repaired AND who they think would be best to do the repairs. This service is free so make use of it.

I'm fairly sure the water is running along the bottom of the pipe. You can try to get the original builder to repair it. If he values his reputation (assuming it was good) he will repair it at his expense. RARELY will you get any builder to guarantee a lek free pond, but this sort of thing can be bad for his business.

Watch out you Texans---Kenny makes 3 new missourians this week!

K-man,
Welcome to the forum; glad you joined us.
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How do we know that your spillway pipe is dropping? What empirical measurement do you have? Do you have an existing, stable benchmark anywhere on or around the pond that can be used as a reference to the full pool mark? (like a dock, nail in a tree, or whatever) Use it to shoot an elevation to the bottom of the spillway pipe to see if it's elevation has changed.
You are saying that the dam is about 210 feet across, and there is a section of about 75 feet within this 210 feet that is falling in elevation...right? And, the spillway pipe is about in the middle of this 75 ft section...right?
Once again, how much of a difference in elevation in the top of the dam between the unchanged and depressed area? Also, can we shoot the elevation of the top of the dam all the way across and compare it to the benchmark to see if there has been any settling in the dam soils?
How tall is the dam? What compacting practice was employed during it's construction?
How was the spillway pipe installed and at what point during dam construction?
There is alot of input that can change the analysis of your situation. Rainman and TomG make reasonable assessments, but something as simple as settling might be in play. Maybe not any of this and somebody like Mike Otto (our resident dirt guru) will massage the entire picture and offer alternate advice.
We installed our spillway pipe after the entire dam was constructed. The track hoe was used to cut a ditch directly into the dam. I held the laser rod and called out the elevation as my dirt-guy carefully trimmed down to the exact depth to put the spillway pipe. We then backfilled as I power tamped the soil around the pipe, filling the ditch back in. Within 18 months, the entire ditch area had settled about 4" - 6" lower than the surrounding dam. It's the difference between soil compacted by a jumping jack, compared to soil compacted by a loaded rubber tired earthmover. We fill in the sunken area this past spring and all is well.

Welcome Kenny Lee you are going to love this place.

I can only offer the same as Tom G, Rainman, Brettski.

First does the dam leak? Can you see any water running out the back of the dam along the pipe?
Has the pond ever been completely full?
You really need to measure the elevation like Brettski said to make sure exactly what you have. All dams settle some. But the dam has to be higher than the spillway,PERIOD. It may look a lot worse than it really is, At least lets hope so.
Otto

I'm going this weekend and I'll take some pics. of the slump.
I don't know for sure what the height of the dam is, but roughly measured the depth on the water side when dry to the bottom of the seep tube to be 24 feet.
I had the builder flag the water level and the maximum water level (spillway height) so i could build my dock. The dock sould be 1 foot over the spillway height, but its about 4 feet above the water line.
I was not there when the seep tube went in, the builder told me they assembled it on site 110 feet of pipe with a steel collar in the middle, he also said that he soaked the ground around the pipe to get good compaction.
All the work was done with a D8T Cat.
If water is leaking down the side of the sip tube and causing the slump, what do I have to do to fix it?

An easy and pretty accurate way to check the low spots on the dam is to lay a level on it's side, close one eye (I skip this step, I only have one good eye ), and look across the top of the level to see how big the differances are.

Sounds like you're saying pipe & all has setteled 3ft ???

Kennylee

If the slump is caused by water leaking around the pipe you will have to dig the pipe out and re set it. that is not really as big a job as it sounds but the important part will be the installation. The dirt will need to be compacted from under the pipe to the top of the dam.

First measure the elevations to make sure it is as bad as you think. I have a hard time seeing a dam settle as much as you are thinking and it not breaching. Keep us posted

Otto

The next time the water is flowing trough the pipe, chek the areas between the dam and the out flow of the pipe for any abnomally wet or soft, spongy areas too.

If this thing has sunk nearly as much as you think, the dam will have to be washing out from the inside and would be catastrophic if it failed all at once rather than being topped and eroding away quickly.

How tall was the dam? Your average depth and acerage again??

I'm going up tomarrow, I have my camera,laser level and 100' tape, i'm going to take pics and measure the slump, check for damp soft spots on the back of the dam.
I will post the info sunday or monday when I get back.
Thanks for all the support you guy's have been giving.
There was a steady rain all day tue. so the pond should be full to the bottom of the seep tube.

Back from the country, took some pics and some rough measurements with the laser level (batteries must have been low very weak line), also inspected the back of the dam for leaks, and all looked good.

The creek below the dam where the drain pipe drains, was a rusty residue.

I don't think there is a leak, I think it has settled and this being the thickest part of the dam, it has settled more than the rest of the dam.

I drew a rough sketch of the problems and some of the measurements I got, and will be getting the pics I took posted as soon as my dumb self can get them from the camera to the computor and in to a post,lol.

Well i'm having problems posting the sketch too.

http://www.flickr.com/photos/18003071@N02/2941761299.jpg

This is the back side it's shows the slump better than the front side due to cattails on the front. The crude picture I drew has some of the measurements on it. I've put a call in to the builder and am waiting for his call.
It looks to me that the dam has settled along with the drain pipe, and from the measurements I think the pipe sould be at the height of the slump and the dam needs to be raised and leveled to the height of the rest of the dam. any ideas or coments would sure be welcome.

Your pipe should be set at least 1 1/2 x pipe dia. to 2 x pipe dia. below the emergency spillway elevation.
Dam needs to be higher than emergency spillway elevation.

Not near as worried when you said the dam was not leaking. It looks like adding a little dirt will not be a problem.

Otto

As I said earlyer the seep tube is about 4 foot under the intended water line, and the slump is 20 inches under the spillway and my question is;

What is the best way to raise the water line back to the intended level?

Do I have to have the seep tube dug out and reset, or can I fill the seep tube with concrete and put a siphon system in at the current level of the slump and level the dam off?

Can you add a piece of pipe to the existing seep tube to get it back up where it needs to be.
YES. you can fill the seep tube with concrete, and put a siphon system in.

The picture you posted looked like you had a wide grade on the side. In an emergency you could get the dirt from that area and but it on top of the dam. The best thing would be have some dirt hauled in put in place and compacted.
Otto