Our Clients often ask about installing a waterfall and pond in a garden with no hill or elevation. I suggest strongly against trying to create your own hill behind your pond for the waterfall and usually try to suggest alternative water features that don’t require a hill. There are many ideas for water features that don’t require a high hill for the waterfall and will still be a strong focal point in your garden. Think about using one or a small group of ceramic pots with water bubbling out of them, or a basalt column water feature with the water either bubbling out of the top of the columns or shooting up in a geyser between them. These types of water features will be less prone to the problems you may experience trying to build up your own hill.

You might also consider creating a gently flowing stream with short drops instead of a high hill. Most homeowners can use the soil excavated from the pond to create a gently rising stream area to flow into the pond. This new area can be compacted more easily so it won’t sink later after the stream has been installed and it will seem more natural in a garden that doesn’t have any other elevation. Make sure that you plant densely around the stream after you install it for a very natural look.

If you have your heart set on a waterfall and just can’t imagine any other type of water feature consider this:
• You will need to bring in about twice the amount of soil that you will be excavating from the construction of the pond. There won’t be enough soil from digging the pond to create a large enough mass to make the hill behind the pond seem like it is natural and in scale with the pond. What a lot of people end up with is what I call the “mole hill” or a “mini-volcano” behind their pond which looks very contrived.
• As you excavate the pond, pile the soil near the pond where you are trying to create the hill.
• Every time you get about 6” of soil piled up, lightly wet it down and compact it using a rented gas powered compactor or if you must, using a manual plate compactor.
• Do not pile up all the soil into a hill and then try to compact it because you’ll only compact the very top and after you’ve built your whole waterfall it will continue to compact and sink over time and your waterfall will sink along with the soil and eventually not work properly.
• Plan on having additional inexpensive heavy fill soil delivered to your site and install that along with the excavated soil, compacting it every time you lay down 6” of soil. Do not use light planting soil for this part of the project. You need soil that will compact and hold up the heavy waterfall rock.
• You should end up with a hill that is wider and deeper than the pond in front of it. This larger hill will seem more natural in the garden.
• Now you can install your waterfall into your pond and after that is complete you can bring in additional light planting soil to build the hill out even a bit more for planting. Install some boulders on the hill to make it feel more natural and plant the whole space densely.
If this seems like more work than you’re ready for remember that Falling Water Designs can install your water feature for you.