How to Construct a Concrete Pond
Estmating the materils
>Excavating
To drain or not to drain
Placing the forms
Working with Concrete
Pouring the Floor
Setting
Fountains and Spouts
The amount of work you will have to do depends upon the texture of the soil in which you sink your pond. If the soil is firm enough for an excavation to hold shape-a heavy clay, perhaps-you will need to build only one form, the inside one, to hold the concrete. The faces of the excavation can serve as the outer form.
If tile soil is crumbly, possibly with a lot of sand or gravel in it, you will have to build both inside and outside forms. In either case, it will be wise for you to lay planks along the edges of the excavation as you dig so they will hold up cleanly under your weight.
The length, width, and shape of the pond are up to you, but ideal conditions for growing water-lilies-ideal for their well-being and for your convenience-call for a water depth of 2 feet. This allows about a foot for the containers of soil in which the lilies will be rooted and a foot of water to cover the crowns of the plants. A pond this deep will allow flowers and plants to grow comfortably, and yet it is not so deep as to make the business of climbing in and out of it to plant, to rearrange flowers, or to clean, a difficult or awkward job.
Add another 2 inches to the height of the walls, because ponds look best when the water level is about 2 inches short of the brimming point. Allow up to an inch of side wall to extend above ground level so as to keep surface water from draining in during rainstorms.
Save the sod when you make the excavation. Set it out of the way and give it a good watering now and then. It will be handy for patching up or for edging the pond when you are finished.
For a pond 2 feet deep, excavate to a depth of 3 feet. Six inches of that extra foot are to be filled with hard-tamped cinders, gravel, or fine crushed stone. The other six, of course, will be the layer of concrete which forms the pond floor. An ideal thickness for walls is also six inches.
When you get the excavation down 2 feet or so, take pains as you progress to keep the floor as level as possible. Slight irregularities in an off-level pond bottom are easily covered over by the concrete. A big irregularity is another matter, indeed.
An excavation made too deep, and then corrected to the desired depth by refilling with tamped earth, is dangerous business. Replaced earth, no matter how hard it is tamped, is not as solid as it was originally. Thus, a concrete pond built into a half-true, half-refilled excavation, sets upon a half-soft, half-hard foundation.
Water weighs more than 62 pounds to the cubic foot. In an 8-by-10 foot pond, 2 feet deep, the water mass weighs nearly 5 tons-enough weight to break a pond shell in two as easily as you would crack a yardstick over your knee.
A check peg is as good a device as I know for assuring a level excavation.
A few feet away from the pond site, where it will be out of the way, drive a stout stake into the ground and mark some arbitrary point upon it, say a point a foot above ground level. That will be your check point.
Now drive a long stake into each comer of the excavation. Run a string level, or a straight board with a carpenter's level secured to it, from your check point to each of the corner stakes and mark each stake accordingly. Now your excavation is marked in all its corners with points which are level with each other, and you can measure downward from these points to establish a truly level excavation.
From this point forward, you move in one of three ways, depending upon the type of drainage arrangement you prefer for your pond or whether, indeed, you want any at all. Whatever arrangement you decide upon must be provided for now, and, if pipe lines are to be used, they must be placed before any concrete is poured.