Part 4 of 8: Excavation

There are many ways to construct a pond, but we recommend using a fish-friendly flexible pond liner. You may also consider a pre-formed pond insert, a concrete pond or an above ground pond. This section is limited to ponds built using flexible liners. We feature flexible, durable, affordable EPDM pond liners from PondKing.

Once you’ve selected your site, use a garden hose or rope to lay out the shape of your pond. Move it around and look at different shapes. Play with it until you are satisfied, and then view it from inside your house and from different spots around the yard. When you’re comfortable with your design, use spray paint to mark the outline, take the hose away and look at the shape for a day or two. Make sure you like its placement from inside and outside. For rectangular or square ponds, use string, stakes and a carpenter's square for your layout. There is no right or wrong way to design a pond … the choice is yours.

After finalizing the location and shape of your pond, the next step is to position your waterfall and skimmer box. To maximize enjoyment of your garden pond, place the waterfall/filter unit facing the area from which you will view your pond most frequently. The skimmer is placed at the opposite end of the pond for optimal circulation and filtration.

Before planning your waterfall, you may want to visit natural waterfalls or look at photos to get a general idea how water flows around and over the rocks. The design of your waterfall will depend on topography, pump and pipe size, length of water flow from pump to falls, pond size and, possibly, other site-specific factors. While it is tempting to make a very tall waterfall, in reality a 2-foot drop will produce a very satisfactory effect both visually and audibly. Keep the elements of your water feature in scale. If your pond is just 4x6-feet, for example, you don't want a large, three foot wide waterfall.

The waterfall/filter unit should be placed on level, stable ground and above the water level of the pond. If you are working on a slope, you have the option of placing the waterfall/filter uphill from the pond and creating a series of cascading waterfalls. Even on a level site, it's a good design strategy to place the falls six to eight feet from the pond to create a short stream to the pond. The waterfall unit must be leveled from front to back and from side to side. If it is not leveled the water will not flow properly, and your waterfall may leak. The skimmer box should be placed at the opposite edge of the pond. Click here for more information on building your waterfall.

Before you start digging, you will need to decide if you are going to build your pond with straight vertical edges or with a shallow shelf area to hold aquatic bog plants. If you live in an area with predators such as raccoons, or even housecats, you might consider a pond without a shelf. This will keep out most land predators.

Bog and marginal pond plants improve the beauty of your pond and the shallow area created by a shelf makes it easier to view your pond fish as they come up to the shelf area for feeding. The pond's sides should slope slightly inward from top to bottom at about a 75 degree angle. Check the pond's depth during excavation by using a yard stick or tape measure. If the pool edging will be sod, cut the sod in 10-inch sections and roll it back from the excavation approximately 24 inches. Wet the sod if it shows signs of drying.

Once you’ve settled on a design and positioned your waterfall unit and skimmer, you are ready to start digging. If you choose to have a shelf you should dig the entire pond down to the level of the shelf (usually one foot) Then use spray paint to mark the area in which you want the shelf to remain and dig out the pond another 6 to 12 inches where you could place another shelf. Dig out the deep end of the pond and slope the bottom so debris will settle in one area. Excavate a niche for the skimmer box to ensure that water flows in at the proper water level. Check the instructions provided with your EcoSkimmer for exact depth and placement instructions.

Aquatic plants play a very important role in the life of your water garden and provisions should be made for them during excavation. Unsightly plant pots may be eliminated by digging planting pockets into the shelves and filling them with soil and organic cat litter after the liner is in place. We recommend digging several planting pockets.

Place the excess dirt near the waterfall location to be used to construct a berm around your filter unit. On a level site, with an average size pond of 11x16-feet, the amount of soil needed to surround the biological filter and create a berm is just about equal to the amount of soil excavated from the pond. To further enhance or enlarge the berm, you may need to add a little more soil, large boulders or other features.

Place a straight 2x4-inch board on edge across the excavated area and check the level of the pond's rim with a carpenter's level. Remove or add soil where needed until the entire pond edge is level. This step is essential, because the liner will be clearly visible where the edge is uneven.

Complete the final shaping and double check all depth and leveling measurements again. Be sure no rocks or tree roots protrude from the pond sides and bottom. Smooth out the entire pond with a rake and line the bottom of the excavation with about and inch of damp sand to cushion and protect the liner. Install an underlayment to provide additional protection. We sell a non-woven fabric made specifically for this use. This material provides tear and puncture protection for your liner, plus it helps stabilize the soil and prevent erosion.

The next step is to install the pond liner.