When you have settled on a design and have drawn a plan for it, a couple of things to think about concerning construction. Build your pond just like a small swimming pool, with 3/8” rebar installed in a grid pattern 10” O.C. maximum, with no vinyl liner (it’s a waste of time and money, and is going to get holes in it anyway). Contact “Dig Alert” or whatever they are called in your area to locate any underground utilities and their pipes and things before you start excavation. Do not forget to do this! When excavating, create a shallow area for the waterfall to be placed inside. The waterfall should be constructed inside the pond basin in this shallow area, which amounts to a large shelf inside the pond. In this way, the pond can never lose water because it is all contained inside the pond basin even if the watefall leaks. After your pond is excavated, dig a trench for the intake pipe (2” minimum diameter), then refill trenches with clean fill that is free of any rocks to prevent pipe damage over time.
Set a form for the pond edge perfectly level all around the perimeter except in the area of the waterfall. Use a contractor’s transit level to do the pond edge. This way when the pond is filled up completely, the concrete edges do not show and ground cover and other plants can grow over the pond edges, giving as natural a look as possible. If there is a waterfall on a hill that is flowing into the pond, then a flat but slightly sloping extension of the pond must be added to the area where the falls will be to catch all of the water and return it to the pond. The edges of this “catch basin” must be raised 6”-8” to keep runoff from getting in and pond water from splashing and running out. You are ready to set your steel in a grid pattern. Steel may be set as close as 6” o.c. or as much as 12” o.c. Form steel tightly to the ground. Later, install dobies (small blocks of concrete with tie wire protruding out) under the steel grid in enough places to lift it off the ground. When you pour the concrete, the steel will be totally imbedded in it. Use no more than 40 grade 3/8” rebar, because it is strong and very easy to shape and bend for free-form ponds. The finished concrete should be at least 4” thick. Use loop ties and a tying tool, available at masonry suppliers, to tie the rebar together.
When pouring concrete for the pond, if it’s over one cubic yard, get a cement truck and concrete pump to do the job. Otherwise mix it by hand in a wheel barrow or two, or in a small mixer if you have one. You’d be amazed how many small ponds I have built with a couple of wheel barrows, shovels, mixing hoe, trowels, and just a few workers. After mixing the concrete by hand, lay out the mix as smoothly as possible with a metal float and apply two coats of Foundation Thoroseal. The best concrete mix to use if it works for your climate is a seven sack mix. You may want to consider shotcrete if it’s available in your area. This is pump mix concrete shot out of a large hose under pressure; considerably more than with a regular concrete pump. The shotcrete allows concrete to be applied to higher verticle surfaces without dropping off. Gunnite is certainly another option for applying cement to the pond, and may be necessay where you have large amounts of vertical walls to apply cement to. Concerning the application of the concrete or gunnite: it is probably worth it to go ahead and pay extra and find quality finishers to trowel on the material professionally.
Some people need to know how well the water features hold up in cold weather, and the short answer is to investigate on your own how that issue is handled by masonry, pool, and concrete contractors in your area. Whatever applies to their finished structures is going to apply to these water features that we’re doing. Whatever a home owner must do to winterize their swimming pools in cold climates will have to be duplicated for a waterfall.
Electrical Circuits for Water Features
While you are working on the different phases of the pond, you should be working with the electrical part of the project, too. This should be done by licensed, qualified personnel only. As far as your power source for your project, an existing exterior receptacle is the easiest, most convenient point of attachment. An interior receptacle will also work: simply drill a hole the size of a threaded pipe adaptor out the back of the junction box from the inside of the house, through the exterior wall covering, and attach the conduit to the J-box . Even better is taking the circuit from the main panel box of the house. If you need 220 service for the pump, you must have room in the panel for a new breaker and then create an access to the panel for the new circuit.
When you run a circuit out to the site of the water feature from your power source, whether above or below ground, use 3/4” conduit minimum. Make sure the receptacle for the pump ends up within the reach of the pump’s power cord, but still hidden from view, behind the waterfall or plants. To shield the pump’s power cord from rain or sprinklers, install a waterproof cover by Intermatic. Using 3/4” or 1” conduit, and stranded, 12 or 10 gauge wire makes wire pulling much easier, especially when there are numerous turns in the conduit and long runs to pull through. Pull an extra hot wire or two for future lighting or auxillary circuits while you’re at it; it will make things easier for you. Underground conduit must be schedule 40 pvc plastic pipe installed to the depth specified for your area in the code (usually 18” minimum). Above ground should be galvinized EMT conduit and fittings or per applicable code. If the pump is running continuously, no timer is required; you may want install a switch only. Otherwise a basic Intermatic mechanical timer is all you need for the simplest and most reliable operation.
The water feature should be properly grounded for maximum safety. In addition to the normal grounding to the main panel via metal conduit or grounding wire inside plastic conduit, a solid copper wire, # 8 minimum must lead from a clamp on the rebar grid in the concrete pond shell to the exterior ground terminal on the pump itself. Check local codes and confer with your building inspector to confirm this point. All of the previous information on the electrical installations is not meant to replace careful study of, and compliance with your local area’s electrical codes. The information is a general guide pertaining to water features only and is not represented by me as being all-inclusive. I disclaim any responsibility for any problems you might have in this regard.