concrete collar
The concrete collar is a key component of your pond as it acts as a reference point for the entire build

Ironically, many are unable to see the importance of it and the "do I really need one" question pops up quite often on consults

The collar is the first step in building a proper pond and it's one that shouldn't be skipped

Remember, it can be looked upon as the foundation of your pond much like a house needs a foundation to be structurally sound
What is a Concrete Collar
In the simplest terms a collar is a concrete ring around the circumference of the pond which provides stable base support for the rock. Without this support, rock can sink, tilt and even fall over into the pond. Waterfalls in particular, require a larger pad with footings below the frost line in order to stand the test of time. The waterfall pad is best integrated into the collar and all completed in 1 pour
stone collapse
 stone slanting
No collar was installed here and you can see the rock is about to tip right into the pond
This is perhaps the worst "stone work" I have seen by a landscaper. Not only is not supported and severely slanted, the stone quality is poor
Other functions of the collar
Besides maintaining stable rock work, the collar has many other key benefits. First, it defines the size of the pond. When your building larger ponds it can be very easy to lose sight of "a hose" or marker paint which defines the edge of your pond. Add the odd cave in, and your measurements and design will be altered dramatically

Another important benefit is that the collar establishes level. On the typical DIY pond, you will often see 5 inches of liner on one side, and the pond about to overflow on the other. Aesthetically this looks terrible and being level is a 101 concept

I remember one pond we built we found a large stone. It was interfering with the shape of the shell and needed to be removed. Without the collar in this instance, the whole side wall would have crumbled in. On more than 1 consult, insistence to install a collar has met with resistance. On one particular instance, the client did not heed my warnings. The following Spring I returned to see a collar had be installed. Laughingly, the client said "you were right". There had been several collapses and everything had to be rectified. Remember it requires work to reduce work

To summarize, the concrete collar provides a stable base for your stone, it defines the size of the pond, it sets level for the build and stops soil from caving in





pond excavation
The collar has been dug out and is ready for the concrete to be poured
   
This photo illustrates the difference in grade that often exists. At the close end we dug down 1.5 feet, the far end only 1/2 foot
 
Rebar is essential to strengthen the collar. It is optimally placed in the lower third of the concrete for best structural strength
 
Concrete should be allowed to cure slowly. It should be sprayed down lightly with water a couple times a day. Quick Set and overly wet mixes are structurally weaker
 
The collar is complete and now the excavation and plumbing work can be installed


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Last Modified: October 29, 2009
Created: December 2007