So you read last week’s garden column and I’ve talked you into adding a water feature to your yard. Go for it!
This week, we’ll take a look at two different products you can use to construct a pond. But just remember, there are a few things you should check out before you dig that hole.
Make sure to follow any restrictions your town might have regarding water features. Some towns require a permit or even fencing if the water is over a certain depth.
If you have any underground utilities, be certain you know where they’re buried. When we lived in Illinois, I chopped up the whole neighborhood’s cable wire with the rototiller on several different occasions because our cable company never came and marked the line when I’d called.
If you or your neighbors have young children, remember that even a shallow pool of water can pose a threat. Consider postponing your plans or modifying them so that you eliminate any risk of drowning.
What size pond is right for the spot? If you wish to keep it small, you can use a preformed shell. Made of fiberglass or polyethylene, these shells offer several choices of shape and size. While the fiberglass version is more expensive, it is also more durable, lasting 10 to 30 years. The plastic shells are generally the type found at home improvement stores. The drawback is that the material may become brittle as it ages and is apt to break down with exposure to UV rays. This type should last three to 10 years. I have had good success with this less expensive, plastic type.
Whether plastic or fiberglass, the preformed shells generally have shelves for plants. Both types must be supported sufficiently so the pressure of the water will not warp them.
The other choice of pond material, without getting into concrete, is a flexible liner. Flexible liners come in many different sizes allowing you to be, well, more flexible in your design. PVC is the least expensive material choice and will last for about 10 years. EPDM (ethylene propylene diene monomer) is a more expensive option and will hold up much better than the vinyl. Whatever lining you choose, be sure it is specifically made for use in ponds so that it is free from chemicals that could harm fish or plants.
Whether you choose the preformed or the flexible liner, the installation procedure is much the same. Each should be located on a fairly level site, although it is possible to build a retaining wall on a sloping side. This should be done in advance, if required.
For a preformed pond, place the shell on top of the ground where you wish to locate it. Mark where the outer edges fall and start digging, taking care to follow measurements for any shelves. If you’re using a flexible liner, use string or a length of garden hose to form the desired shape. Then dig, making sure to include shelves for plants.
For either type of pond, dig two inches deeper than the measurements to allow for a layer of sand. Once the hole is roughed out, check for level and make sure any sharp objects are removed – rocks or roots can puncture the bottom of your pond. Then add the two-inch layer of sand and level once again.
If you’re using a shell, lower it into the hole and check for fit. Make sure every shelf is adequately supported and that the shell is level. Once you’re sure of the fit, you can fill the pool with water from a garden hose.
At this point, if you’re installing a flexible liner pond, before it is added you must line the hole with liner protection fabric. This fabric can be purchased where the liners are sold. Some people use thick layers of newspaper for this purpose instead.
When computing the size liner you’ll need, draw a rectangle around your pond’s outline and measure its length and width. Then, to both of those measurements add twice the pond’s depth plus two feet for extra material to extend beyond the pond’s edges.
Once you have the correct size liner, spread it out on a flat surface in the sun so it has a chance to soften. When you’re ready to install it, it’s a good idea to get a few friends to help. Make sure as you spread it out in the hole that you have extra material on every side of the pond. Then, weigh that extra fabric down with rocks.
As you fill the pond with water, smooth out as many of the wrinkles as possible. You won’t get them all. Then, before the pond is completely filled, set the edging in place, catching the liner underneath. Most people use boulders and rocks for this. Although bricks and other types of pavers may be used, usually these are affixed by mortar. This is not always the best idea in our cold climate, where frost is apt to heave them out of place, cracking the mortar.
Next week, we’ll talk about pumps and other equipment needed to complete your pond, as well as optional features like waterfalls and fountains.
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