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Building Natural Rock Waterfalls

Laying the Rocks in Your Cascade Design


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Stones from left to right: 1st spillway, 2nd spillway, capstone.

David Beaulieu

On Page 3 we considered rock selection for building natural rock waterfalls. I conclude this article with a look at laying the rocks and working with the tubing that carries water from the pond to the top of the natural rock waterfall.

Invert the flower pot and thread your tubing through the hole in its bottom. Place the pot on the ground (still inverted) at the center of what will be the rock waterfall structure. How far in back of the pond should this be? Well, that depends on the depth of your rocks. You'll want the rocks that face the pond to abut it; if possible, they should even overhang the pond slightly. So if the rocks you'll be using there are 8" in depth (i.e., front to back), the front side of the pot should be about 8" back from the edge of the pond.

How long should the tubing be? Where on the ground should it rest? Well, as far as length goes, I would advise against trying to get a perfect measurement right away and then cutting. Instead, leave yourself with a length that is longer than what you'll need, and trim later as necessary. This will make your job a lot easier! As to where to run it along the ground, choose either the left or the right side of the pond and rock waterfall. As a cosmetic touch at the end of the project, you can go back and hide it with stones and/or mulch.

Typically, when building rock walls, it's a good idea to stagger the seams. Of course, these will be very small rock walls, so it's not a structural concern here. Still, try to do some staggering, if only because it looks better.

As already mentioned in speaking of rock selection, after my first course of rocks in the front, I layed 1 long flat rock spanning them all. Because this rock's function is to form an overhang, it's a key piece in your cascade design. Using it as a shelf, you'll place your first spillway rock (see below) on it, in such a way that the spillway rock overhangs the pond even further.

Continue laying the 4 walls, until you've reached the height you desire. Once you're done encasing the pot with the 4 walls, you need to place 2 longer stones across the top (either front-to-back or left-to-right) to span the walls. Pull up the tubing to gain more length, if necessary, and gently sandwich the tubing in between these 2 longer rocks to hold it in place.

Begin trying to position your first spillway rock on top of your shelf rock. It should jut out over the pond even further than does the shelf rock (ideally, the tip would line up over the middle of the pond, although this is difficult to achieve). Elevate the first spillway rock in the back, to achieve better water run-off. You can elevate this or any rock in the wall by using shims (small flat stones).

Bend the end of the tubing down towards the pond and place one or more capstones over it. It is under here that the waterfall's "spout" will rest, so to speak. By "capstone" I mean a stone that will partially hide the tubing and/or gently press it down against the second spillway rock (as yet uninstalled). Make sure most of the capstone's weight rests on the rocks between which the tubing is sandwiched (or on shims), so that the tubing doesn't become flattened. You'll have to play with the level of the spout, as you begin to fit in the second spillway rock.

Begin trying to position your second spillway rock on top of your first spillway rock (see photo, above right, in which the second spillway rock is the rock which the gush of water is striking). Again, elevate the rock in the back using a shim, to achieve a steeper pitch. One way to think of the placement of the 2 spillway rocks is that they're like 2 shingles on a roof. They're both on a slant, and the top one overlaps the bottom one, forming a continuous chute down which the water can pour.

The position of the end of the tubing that forms the spout can now be determined more precisely, as you size it up on the surface of the second spillway rock. Again, pull to lengthen or shorten your tubing, as necessary.

You're ready to fill the pond with water, plug in the pump's cord, and test the flow of your natural rock waterfall. No doubt, you'll have to make several adjustments before you get everything right. The objective is to get the water to fall as close as possible to the middle of the pond, so that you can minimize water-loss from the splashing that will incur. Note, however, that there's some compromise involved with your cascade design: greater height equals greater visual impact, but greater height also equals greater water-loss (as the splashes will be more violent). Another consideration on height: keep your natural rock waterfall in proportion with the pond. A general rule of thumb would be, the smaller the pond, the shorter the rock waterfall.

When undertaking projects such as building natural rock waterfalls, always keep home safety tips in mind.

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