Pond Boss Forums POND CONSTRUCTION Building a dam Dam Core Question

Is there a ratio of how wide the core needs to be relative to the width of the dam. After perusing a few of the threads here, I was surprised to see that a core can be as narrow as a couple of feet. For some reason I thought it would have to be 4' or so to be effective. What is the narrowest one can be and still work?

I am meeting with a pond builder to help me with my dam problems that I discussed in the dam seepage thread and I'd like to be able to have some options to discuss with him. Building a core 18' or so in width sure seems a lot more affordable than what I had in mind.

I would think the quality of fill material would determine some of it..

It might be in here:
http://www.in.nrcs.usda.gov/pdf%20files/PONDS.PDF

I would think a minimum 2 foot thickness of good, compacted clay would be adequate, but difficult to compact. The width of whatever is used to excavate and compact would probably be more than enough, if a dozer or trackloader is used.

This is a good question for Otto....

I thought Otto was the one I read that said that there is a small, narrow compactor that can be pulled through a dam core trench. And did I recently read here that someone was recommending the use of gypsum board (sheetrock) be added to the bottom of a pond to help seal it? I know this post reeks of pond leak desperation, but I swear that I read that here somewhere.

Your not crazy RH, both of those things have been discussed here at some time or another, and I think it was recently too.

I remember Otto talking about the narrow sheepsfoot roller too. His description was similar to what I have seen used with a trackhoe. It fits on the end where the bucket goes, and is moved around into places where its to steep or narrow for a regular sheepsfoot roller could go.

But for size of core, call Otto as already recommended. He should be in the resource section.


..Jim

Thanks fish, for a moment there I thought I might be losing my mind! It seems that I have seen a sheeps-foot on a track hoe somewhere before. I've called Otto, but that guy is tough to reach. Right now I need to head out and meet with a pond repair guy and hope that the news is not too bad. I'm in the last stages of building a new house and the budget is stretched to the limit, but the pond location is integral to the house such that a dry pond would really detract from the finished product.

There was another recommendation to someone by Zep in this thread.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=331178#Post331178

Again, thanks Fish. I just got the news that it would cost upwards of $18,000 to build a 10' wide core in my pond dam. That is certainly more than I want to/can spend now as I am in the final stages of building a new home. I had read on this site that some are building cores of only 2' wide; maybe Mike Otto again?

By my reckoning, it doesn't seem important how wide a a core is if it is impermeable. A cereal bowl is pretty thin and it holds milk. This concept was new to the pond builder who showed up to consult me this morning, but he found it intriguing. He felt that it should be at least 5' wide to allow for proper compaction. He didn't feel like the pond bottom was much of a problem, only the dam. I hope he is right. I'd hate to keep dumping large sums of money in a literal hole in the ground.

Also, he mentioned some sort of liquid pond sealer that I could try. He has never used it, but thought it might be a route for me to try first. Anyone know what this product is and has anyone had a positive outcome using it?

You know, it seems like Bill Cody ( --I think) mentioned a sealer not to long ago that was used in a trench that was going from a basement to a pond that was leaking. They used it, and was impressed it worked so good. Could have been in a very old thread I was reading too. Might PM him to see if I am thinking right.....

Couldn't you use a walk-behind vibrating compactor like you use for installing sidewalks and compacting the base? A lot of walking back-and-forth with only a few inches of lift at a time, but I don't see why it wouldn't work.

Most clay pond liners are 3', so I would guess you would want at least that, even for a core barrier.

Did you ever get a $ amount figured out to line the basin with clay, and is it cheaper?

Like you said, you don't want to keep throwing money into it on "may be's". So, if you can't afford to do it the recommended way, best to wait and save up till you can...meanwhile keep researching.

EDIt---oops. I don't know why I was thinking 3'. Looks like 18" or more for a clay liner.... Hopefully somebody will chime in and give a confirmation one way or the other.

Anybody have any experience with ESS-13? It is a non toxic pond sealer that can be dumped directly into the water.

http://www.seepagecontrol.com/how_it_works.html

I did get a price on lining the entire pond with 18' of heavy clay compacted to 12" and it came out to about the same price as coring the dam; $18000. I questioned whether it might be wise to put a plastic liner under the soil at the bottom of the pond. It seems that it would help slow down any water leakage without costing much to do it.

This won't help much, but kind of answers your question


http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=331024#Post331024

Well hell!

Found it. Its called Aqua Blok. Here's the thread.
http://forums.pondboss.com/ubbthreads.ph...true#Post326146

However, this looks like it fills a crack or hole. Probably not what you were thinking of needing.

With the high cost of coring the dam ($18K) or lining the entire pond (also $18K) and with both options coming with no guarantee and big maybe's; I'm now considering buying a liner. It will cost about the same as the work above, but at least it is warranted against leaking. Thoughts?

UV resistance? Going to cover the liner with soil?

How hard to patch? 1 hole = leaking pond.

Going to want to add a pier in the future? With a liner it has to be a floating one.

Muck will build up in every pond. Without a center drain in a lined pond, how will you clean it out?

Is that price material only, or all materials needed and installation?

To attempt to answer some of these questions:

25 year warranty on a RPE liner against UV and general breakdown;
I don't know how hard it is to patch, but since it is meant to be seamed, it must not be too difficult to patch. The cost of the liner will be $18-$20K.

I'm guessing I would pump it out to drain it as I would have to do with my current situation.

Yes, that is the price of the materials only and there are no further materials needed.

My wharf is already in place and that would be a problem to work around as it is pretty large with about 8 metal poles cemented into the pond. I'm not sure how I would work around them.

I don't have the best soil, sort of a clay/sand mixture so I am trying to come up with a solution that is a long term one. Water is also at a premium in the Austin area. My pond doesn't leak so badly that a hole in the liner automatically means a draining pond. I think my problem is primarily in the dam, but the pond repair people will give no assurances that coring the dam will solve my problem and that is after quoting an $18K repair price.

I'm really stuck on how to go about this and there isn't much in the way of help in my area. Just finding a dozer operator who works on pond is very difficult.

Check out this site: http://www.everything-ponds.com/large-pond-liners.html

Make sure that you use an underlayment if the warranty specifies that you need one to keep the warranty valid. Also, make sure the warranty doesn't need an approved installer.

Check on what it weighs and make sure you have the necessary equipment or manpower to move it and place it.

If you haven't done so already, try calling the Pond Boss Office and/or Otto's Dirt Service for a recommended pond guy in your area.

There area few guarantees in life, but you can minimize your risks.

Let me attest to how damned heavy that rubber stuff is. A good 18x20 liner for a garden pond is about 300 pounds of the thick material, it is still sitting by my shed waiting for a "team" effort. I cannot imagine dealing with 3000 pounds or more of the stuff at once, while trying to weld it among other things.

I would get some more quotes on re-coring the dam. Seems pretty darned expensive to me. Exorbitantly so. For that price you could dig a really narrow ditch, toss in some rebar and concrete, and call it a day. No roots, critters, or minor floods would wreck your day from that point onward. Of course concrete is pretty pricey these days too.

liquidgold, since you mentioned concrete let me explain what my latest idea is. One of my close friends is the top dog in the engineering department at the University of Texas and is one of the world's leading authorities on concrete.

I ran this idea by him last night. I am considering digging a 1' trench 10' deep down the length of the dam to a depth of 2' below natural grade to serve as my core. Then using a pump truck, pump fiber filled concrete (since I can't really use wire or steel) into the trench. To insure the concrete impermeability, I can use a gallon of sodium silicate in each load to waterproof the concrete. The pond level is now below natural grade, so wet soil in the dam causing the sides of the trench to collapse should not be a problem.

Cost wise, this is a much cheaper solution: a 10'X100'X1' = 1000 cubic feet of concrete or about 37 yards; $600 for the pump truck and whatever the excavation costs are to dig the trench. Right now concrete is $73/yard where I am located so that is about $2700 of concrete and if it works it is longterm solution.

Dr D ( my buddy the engineer) thinks this is an intriguing idea and his main concern is that the trench might be difficult to excavate 1' without the sides caving in. (I'm thinking that the soil compaction will take care of that.) Even if I had to go to 2' wide, it would still only be $5400 compared to over $8000 to buy clay not counting the $8000-$10,000 in machine and labor costs to core and compact the clay and pond.

What does this forum think of this idea, will it work?

FYI that is what they do with reservoirs around here. A local park has two hugemongous earth dams with a 10" or so concrete core running the length. I can see where it has cracked in places over the years of settling, but neither one of those dams leak. Expect it to crack, but I cannot think of a more effective "plug".