The small pond was dug in a conventional manner, leaving 12 inch ledges for plants, to a depth of 3 feet. Anything over 24 inches will not freeze and fish can hibernate by staying at the bottom over the winter months. The hole was lined with 45 mil EPDM rubber. You may have noticed the rubber hanging from the roof of what was left of the Oklahoma City Federal Building. EPDM is that same material, but made nontoxic for fish. But the large pond was constructed very differently...

The large pond is made of "gunite", air-sprayed concrete, with fiber reinforcement added to the concrete mix. This picture shows the start of the gunite process, stretching the 4 inch hose from the gunite pump some 75 feet to the hole in the backyard.
Here Floyd Bair is attaching the hose to the gunite pump. It will put both air and concrete into the hose line.
Little did john know what a long, but fun, day this would be. The Bair Company took fourteen mixing trucks of concrete (42 yards) and 13 hours of spraying concrete to finish the pond walls. This work cost john $6000 and was well worth it!
Gunite is amazing in that it requires only Kraft paper lined with chicken wire to spray against. For extra smooth or graceful curves, 1/4 inch masonite was also used as a form. Once a little of the gunite has set up, it makes it's own form!  
Note the rebar on 9 inch centers and the white drains on the bottom of the pond. These three drains were placed in the bottom of the pond with 2 inch flexible hoses attached. They have pressure-relief valves to allow rain water under the concrete to come into the pond. This prevents the pond from floating or cracking from underground pressure. Also, note the black 4 inch pipe running along the bottom. It will go to an external settling tank and be part of a surface strainer system. There is another one just out of sight on the right.
Gunite is starting to flow out the hose now.
Within 1/2 hour you could stand on the concrete, so workers shaped and smoothed the concrete very quickly after it was sprayed.
Spraying more gunite. Afterwards the area behind this wall gets filled with gravel and compacted dirt and makes the base for the large waterfall. A 4 inch PVC pipe was put down before the gravel and dirt to allow a way to provide for expansion of electrical or other plumbing later on. Empty landscape electrical and sprinker system tubing was also laid under the pond before the gunite was sprayed.
The shallow portion of the pond (24 inches deep) was done for two reasons, 1) the power lines for the house ran underneath this area, and 2) this made a great place for a lily pond area. Since koi really can do a number on plants, john figured he would fence the front off and keep this area just for plants.

john washed the inside of the pond with vinegar to neutralize the surface lime and with muratic acid to remove excess concrete from drains, etc. He then spent two days rolling 60 gallons of a rubberized surface compound (HLM 5000, Liquid Cold-Applied Waterproofing Membrane) on the inside of the pond.

If you look very closely you can see groves at the top level of the concrete. These are overflows to direct excess water. Also, not visible here, are four plastic inlets along the sides to provide additional aeration for koi during hot periods.

Note how when water hits the dried rubber at the bottom, it turns a tan-gray color. These pillars are sunk into the ground 3 feet below the pond. They are not going anywhere. A large rock stepping stone have since been mounted on the top of each pillar. The water depth is 5 feet at this point. So far no one has gone for an unexpected swim with the fish.  

Supports for the five stepping stones were made by spraying the gunite into waxed cardboard construction tubes, in this case, 20 inches in diameter.

A view of the steps from the deck and the beginning of the garden beyond. You can see the black pipe (capped with a temporary white cap) at the bottom right. This will be cut off just at water level to become a whirlpool to skim leaves, etc. from the surface of the pond.

Later, john filled the pond with a garden hose for three days. He has since moved 60 tons of rock to edge the pond, walkways and to build waterfalls.


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