Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? New pond owner, new forum member - Questions......

Hi, there -

I've been reading a lot on all of the forums here the past several weeks in anticipation of becoming a pond owner. We closed last night, and now own a property with a 50 year old, 4 1/2 acre pond. (Forums, and all of you, have been a big help - thanks alot!........)

Guess I'll start with a few question here:

1) The pond has a vertical drain (I'll guess 16-20") in one corner, and the previous owner told me that several years ago it had developed a leak (a hole around the pipe) that went 6-8' into the ground. He said they filled it in with gravel and sand, and that the repair worked.

2) One area of the approx. 200' dam has what appears to be burrows, with a couple of vent holes, that I'm guessing are from muskrats. It's not a huge area - I'd guess the digging appears to be confined to a 3' x 3' area.

I am picking up 6 - 50# bags of sodium bentonite from a well driller today.

The pond has evaporated so that the drain is now exposed and I can get to it.

I'm going to try and trap, or shoot, the rats. I'd like to dig down into the burrows, and seal that area from any possibility of more burrows being dug there in the future.

Questions:

- I don't know if the drain has developed any further problems (I'll see it again this weekend...), but, if it has any problems, is there use for the sodium bentonite in repairing it?

- I'd like to dig a hole into the burrows in the dam and seal it. Is there use for the sodium bentonite here? Also, should I be thinking hydraulic cement?

Like I said, I'm picking up 6 50# bags of the sodium bentonite, and it's free. Since the pond has a a foot, or so, under the dam, would the bentonite be of use in the exposed bottom at this point?

Sorry for the long-winded post, and thanks in advance for any suggestions.

Buck Lee

Hello Buck, first off congratulations on becoming a pond owner. Second welcome to Pond Boss. Hang on for expert opinions.

Welcome Buck.

I have never known of sand and gravel actually stopping a leak. I could be wrong but...

I know nothing about hydraulic cement but have used bentonite unsuccessfully enough to respond. I think that it should work if you find a specific hole to use it on. That assumes that the leak/hole is not under a whole lot of pressure.

Buck,

Is the vertical tube supposed to be functioning as your principal spillway?

If it is, then the dam has been living on borrowed time if the principle spillway has been plugged. This would force all the overflow through the secondary spillway (which is usually an earthen, flat bottomed trench around the outside of the dam. The secondary spillway is normally vegetated with a sod forming grass, and is meant to be used only in conditions of 25+ year rainfall events. If the normal trickle of water that needs to go through the dam is routed through the emergency spillway, over several months it will start eroding the spillway from the bottom edge up, and eventually into the dam itself. Then when a heavy rain comes along, the increased flow can eat through the dam and cause it to fail.

If that vertical tube is supposed to be your principle spillway, then you had better try to fix it (if you can lower the water level enough), or plug it and construct another principle spillway that wouldn't vertically drop down so far. That way you might be able to work above the current water level. In either event, you'll want to find a reputable contractor that has had experience in installing these pipes. Proper placement and compaction around the tubes is very critical.

If you've got access to field stone, you might want to cover the face of your dam and below with that, after you get the burrows fixed. Rocks will help deter the rats you don't get (and you'll never get them all).

Bill

Buck, welcome to the forum and congrats on the new purchase!

What is below your damn as far as other property and structures? 4.5 acres of water is not really something you want to experiment with unless you have a VERY good idea of what you are doing. The only way sand and gravel could seal out water is if it was used as a filler for concrete.

I don't mean to be glib, it is just that your description of the dam condition sounds like you could be sitting on a powder keg if a big rain comes.

What part of Indiana are you in? Dave Sefton is an outstanding pond builder near Effingham, Illinois and could give you oustanding direction on how to proceed.

As Bill suggested, your dam may be on borrowed time and we would feel terrible if it gave way on you. There are main spillways that can be installed, such as a siphon system, for a reasonable amount of money.

A word of caution about the muskrat tunnels....if you go digging in them, you will find they are probably much more extensive than you think. Also, digging in the wrong place could creat a dam breach and the whole pond could be empty in as little as a few minutes.

Again, from your description, this does not sound like an issue that can wait and a pro should be brought in for it.

Best of luck and I pray every fear I have is wrong!

Thanks for all the pointers...

We spent this week out there, and I had some better, though uneducated, looks at things: The muskrats appear to have abandoned these dens, for now, so I'll take your advice, Bill, and cover the dam in that area with some stone.

The drain is still exposed, and doesn't look washed out around the pipe.

Finally, thanks for your advice on calling Dave Sefton. I figure that some expert advice now will save me some major grief later, and I plan on calling him. My sister-in-law lives in the same town as Dave......

Thanks again, everyone.