Pond Boss Forums POND CONSTRUCTION Building a dam rebuilding a dam

I just ran across this forum while I was researching for information on rebuilding my pond's dam. I recently bought a 2 acre piece of property that had been neglected for about 20 to 30 years. I have a 1/8 acre pond in the property that is fed by a large drainage ditch. There is about 20 or so acres that feeds the pond through storm runoff. During a good rain, the drainage ditch can turn into a pretty fast whitewater.

My problem is that the dam washed out during hurricane Isabel two years ago and needs to be rebuilt. The pond is around 6 feet deep max, and was dug out adjacent to the drainage ditch I described earlier. The dam must span about 8 feet.

I am looking for advice on where to get information, or help, or experience. Any ideas?

Bump.

I am guessing that the lack of responses here is because we need some more info. Pictures would be great. Or can you ask a more specific question? It would be too obvious to just tell you to put in a good core and build it back.

An 8 ft. wide dam is pretty short. I am assuming that you stopped up a natural "draw" of some kind. For a dam to hold, it would have to be good soils on each side. If those assumptions are true, I would get a dozer in and core it; then fill the opening with good sandy loams that contain around 50% clay. It will have to be well packed at each stage. Next, I would make sure that it had a place for excess water to escape, around a side, over natural ground. Make sure the dam isn't the lowest spot. Moisture content of the fill material is also important so it will pack.

Mike Otto has been writing about dams and pond building in PB magazine for over a year. I would study back issues until I had a pretty good understanding of soils and dams.

Oops, you're right, more information would be helpful. Thanks for bumping this message. My wife is going to take some pictures with her digital camera. I will do a repost with more information. I have been taking advice from a local guy who can figure out almost anything, but may not know everything he thinks he knows. I also don't know the right questions yet.

Dave has made a correct assumption, I am filling in a natural draw. I am currently considering moving the dam building to a narrower portion of the draw and coring the area (I learned about coring yesterday from Dave's reply). I intend to do some studying before wasting too much effort. I am close to the back edge of my property and do not know how deep (front to back) I can make the dam.

My materials I am currently using are cinderblocks for structure, and a mixture of dirt that may not have the proper proportions of clay and silt. Is there a way of determining where my leak is coming from? I have tried putting in a piece of plastic (please don't laugh) where I think the problem is.

I subscribed to the Pond Boss Magazine yesterday. I am looking forward to the first issue.

Dribble Creek,

A couple of comments:

1) Be sure you allow for the slope on the dam...at least 3 to 1. Don't get too close to the property line where you can not have an adequate slope.

2) Leaks are a real problem. If your dam is leaking you can most likely find water seeping from the foot of the dam where it is leaking. The leak itself may be much higher in the dam but it generally is in that vicinity. If the leak is from the pond bottom, you may never be able to find the leak without completely draining. Some folks have tried adding dye to the suspected area to help see where the water exits. It's a difficult problem, often requiring rather expensive mitigation techniques.

I'm not sure I understand what the cinderblock "structure" is for. Did your dam totally wash out or do you have a leak?

Yes....... It washed out, my son and I rebuilt it to partial height with cinderblocks and dirt from dried out portions of the pond, and it has a leak. The dam isn't done yet but we have had plenty of rain lately to test it. The current height should have held. We will take pictures tomorrow and show you the situation.

Ummm, I do have a mess to deal with. I bought the property recently and the original owner built the dam with old metal electrical boxes, organic material, and other "junk".

I have a lot of old rusty electrical boxes if anyone needs any.

Your leak will be around the cinderblocks or other additives. There should be no foreign matter, including rocks, in the dam. Rocks in a dam are a real no-no. I would tear out everything and replace it with loam; no silt added. The dam soil will have to be well packed at each stage. Dam builders often use a sheepsfoot roller to properly compact the newly added soils. Rocks, cinder blocks, electrical boxes and other stuff like that is most likely the reason the original dam failed.

That's what I thought you might say based on your last post. I was under the mistaken impression that the dam required some solid structure. I like your answer better, it makes more sense. Here are some pictures of the situation I am talking about.


The dirt inbetween the cinderblocks is still damp.

The next picture is a view toward the pond.



I am considering starting over on the dam in a narrower location for an easier job and less vegetation. The following picture shows my planned new location for the dam.



The next two pictures are an indication that the pond really is worth saving.




I am going to clean up the site, core the new area, try some of the soil that holds water, and pack it down in layers. Before I get started, is the 3:1 slope that I need 3 in the vertical and 1 in the horizontal or the other way around?

I'll let you know how it turns out.

3:1 - 3 feet horizontally for every 1 foot vertical drop.

Can you build a new dam just below the old one?

Dear Dribble,

Thought I would weigh in here…

If you want a nice pond that you can stock, fish, swim...etc - my suggestion is you hire a local pond builder to come out and give you an estimate to fix your pond. In my opinion - It will probably cost you up to a few of thousand (maybe less) to hire a guy with the right equipment to drain it, dig it out, properly core a dam and clear out some trees. In the precess you can make it a little bigger too. This is assuming you have the correct soil profile. A good builder can tell you all of this. Additionally, save yourself some money and put in an earthen spillway and forget about it. A pond that size could easily be finished in less than a week. It shouldnt cost anything for a someone to come look. Perhaps a little $ for soil tests.

In the end you will be amazed at what a day or two and a dozer can accomplish.

There is NO substitute for the right equipment to perform the right job. However, it’s going to cost you a little up front to get-er-done.

Spend a little and have a nice pond. Get a bid in writing. Then Go for it.

My 2 cents.



Gator

Hey guys, thanks for all of the information and the tips. Yes, I can build a dam right behind the old one. I think I have room.

That is a good piece of advice on the contractor, I will of course get an estimate before starting. I have the name of a good one in North Carolina that has been suggested by the PB magazine.

I have learned an amazing amount in the last couple of days.