We got a bid yesterday on someone putting in a pond for us. 34 grand! Yikes! Too much for us so we want to do it ourselves. The pond we want is to be about 40 by 60 feet and 3 feet deep. I have a Case 580 CK backhoe and a Yanmar YM2310 that will be used for the excavation. I'm sure I will have plenty of questions but the first one is whether to use bentonite or a rubber liner. I don't know if plastic liners are available. My wife wants to do the liner installation if we go that way. Like me she has no idea what is involved with putting a liner in. Actually, that's not true. I have seen pictures of a rubber liner being laid down and the seams being glued or heat sealed. But that's all I know. Any advice is greatly appreciated.
Thanks,
Eric
What type of soil do you have? A liner is freakishly expensive, and there is always the possibility that it will tear or leak for some unpredictable reason. Bentonite helps sometimes, in some soil types, if it's applied thick enough, and worked into the soil properly. There are a lot of things that can go wrong with Bentonite for it to not work, and most of the time, it was never the correct material to use.
In ponds with fish, almost 90 percent of their life is spent in the top 4 feet of the water. When figuring out how deep to go, you have to know how much will evaporate in the Summer to be sure you have at least 4 feet of water. The other issue with shallow water is oxygen in the water for the fish. You will need to create oxygen if the water is shallow with a water fall, or an air bubbler. And if it gets really hot where you live, the fish will need deeper water to stay cool.
If the pond is just for animals to drink out of, or for something to look at, 3 feet might be OK, but if you lose 2 feet from evaporation, it might be not be so nice to look at unless you have a constant source of water to add to it.
About ten years ago, here in East Texas, we had a very hot summer with almost no rain. My big pond dropped 8 feet. It was 14 feet deep on the deep side, six feet deep on the shallow side. My fish survived, but it was pretty scary to see it down so far. Since then, I added 2 feet to my dam to increase the amount of water I can lose to evaporation. My small pond was just 6 feet deep at it's deepest, and most of it was 4 feet deep. It just about totally dried up when I drove my backhoe into it and dug a big, deep hole. I called it the swimming pool, because that's sort of what it looked like when I dug it The small amount of water left in my pond went into that hole, along with hundreds of fingerlings that where still alive. All my mature fish died, included over 60 catfish that where in the ten pound range. They all died on the same day, when there was about a foot of water left in the pond. There wasn't any oxygen left in the water for them, and the water temps where too high. I never saw so many vultures before!!!
Digging the pond with your backhoe is very doable. My small pond is 3/4 of an acre, and I dug it with my backhoe. Most of the work was hauling the dirt out of there one yard at a time. The farther I moved the dirt, the longer it took. I spent several months doing this, and figured 4 feet was deep enough, along with that lower area of 6 feet. When the pond dried up, I dug it down another two feet, plus the swimming pool. That was a good month of moving dirt just outside the pond, and piling it up right next to the pond. It took me another two years to finally get all that dirt hauled off to another area, where most of it is still there. I use what I need, when I need it, but it's been there over a decade, and probably will still be there ten years from now.
My big pond is all red clay, and the very best soil for a pond. My small pond started out with red clay, but then I hit a grey clay that was super hard, and fortunately, water proof too, but it's not like the red clay. You cannot compact it after you dig it, it just dries up and flakes off. When left alone in the ground, it's been great.
Before buying a liner, it might be worthwhile to dig a test hole to see how well it holds water. Dig something like a 20x20 hole six to 8 feet deep, and leave it for a year to see what happens. Does it fill up with runoff? How long does it stay full of water? Then look at your land and see if you can increase how much water goes into it. I built up my roads on my land so they catch rain water and diverts it to my ponds.
