Saturday, 26 January 2013

Ponds Part 2 - Technical aspects

Wow this took a while, I apologise for the delay, but sometimes life just gets in the way. So without further ado, here is part 2 of the pond series.

The benefits of incorporating a water feature like a pond have been detailed in the last post about this topic. In this post I would like to outline how we went about to design and "build" our pond.

On our 1 acre site a good 20% was swamp or wetland. This part had been left completely to itself with bulrushes and cattails growing up to 6 feet high. Frogs resident in this wetland formed a background of noise in the spring time, but there was no visible water....until you stepped into the thicket of rushes and you realised that you sank past your ankles.
Pic 1 The morning of the dig, facing West April 2011

We had each always wanted a pond, and this part of the property looked perfect. We started designing a rough outline and thought about how deep we wanted to make it. Winters here can be really cold and in order to stock the pond with any fish at all it should be at least 6 feet or better 8 feet deep to allow room for survival.

Edge is an important aspect in Permaculture as any edge in nature is always the most biodiverse area in a system. You want to increase your edge, or lengthen your bank, as much as possible and this helps determine the population of fish you can stock, the variety and quantity of edge plants etc etc. Edge can be greatly increased by adding curves and features to the design of a pond so in this respect, a round pond is the worst thing you could do.

We decided to have a random kidney type shape.

The ground on our site is full of blue clay. Once you get to a couple of feet deep that is all you get. Clay is perfect to dig a pond that is able to retain its water without a liner. Therefore we planned not to use a liner but have a natural sealed bottom. We also planned on having ducks in the pond at a later stage and ducks can aid the sealing of the bottom with their poop.

So after all this planning it was time to make a phone call to a contractor that lives just up the road from us. After all, I did not want to shovel the size of my pond by hand.

A short word about contractors for earth moving. Running an excavator or Bulldozer is one thing, but operating an excavator or bulldozer properly and efficiently is another. A pond to some is just a hole in the ground filled with water, and to others there are a lot of factors to consider.
Our earth mover, Tom Egers, is one of those artists with an excavator. Once in the machine it is hard to tell where man ends and machine begins. Tom had built many ponds in his life and offered valuable advice on how we can build our pond and be able to enjoy it for a long time.

The first negative news that Tom relayed to us was that a depth of 8 feet could be hard to achieve. Apparently dirt falls at a 1:1 ratio. Which means for every foot depth you need to go out by one foot. unfortunately we would be getting quite close to the property line and making the walls steeper would result in earth sliding down until that 1:1 ratio is reached. Meaning our pond would "run" into our neighbours property with time.

We settled on a depth of 6 feet and have to trust in global warming for fish to yes.

We knew that the ground is packed clay on most parts of our property, but it can always happen that you hit layers of sand, or even rock. If you are not sure what to expect, dig a test trench. You can do that with a shovel and several hours of work. It may seem like a pain in the back, but it can save you from disappointment.

Digging a pond will bring up a LOT of dirt. It is advisable to plan ahead for all the excess dirt that will be created in the process. You can either have it hauled away or use it. Hauling dirt away from you property is costly, you will have to pay the truck and driver, using it is a better solution. Our pond is situated at a low point on our property and the drop off is rather steep. I had therefore planned to use the dirt to even out the drop off into a slope that can be used for growing food or trees and have a gentle transition into the pond. At this point it should be noted that in order to grow food or trees topsoil is of utmost importance. Generally earthmovers will scrap of the topsoil and put it aside before commencing with the actual excavation. Make sure they know to do this before you let them on your property. This topsoil can then be spread over the parts where you want to establish your vegetation. Good topsoil is worth it's weight in gold, so don't waste it.

Once all these decisions had been made, and all the planning was done, it was time to get down to business.

Oh, I might have to mention another thing. We got an estimate on the cost from our earthmover. This is something that is very important. But, it is always hard to estimate exactly how much time is needed to finish the work and estimates mean nothing if the earthmover does not have a good idea about how long it will take him/her to complete the job. Tom Egers is well known in our community and one thing that we have heard from many other people is that the estimates he gives his customers are never too low. Meaning, you will never pay more than what you are planning with. In my opinion this is a very very important aspect. I have been cheated in the past and that does not only leave a bitter taste in your mouth, but also can severely upset your financial planning. Make sure that the estimates you get are accurate. This means to go out and get some opinions about the people that will be working for you. Maybe talk to other customers of theirs in the past. Tell the earthmover to give you a "maximum cost". I rather calculate with a higher cost and then have money left over than the other way around. Once the digging starts you will not be able to stop it. Or better: you don't want to stop it.

So, now we can begin. Dirt ahoy.
Pic 2: Making the borders

Once the digging has started there is little for you to do. Our earthmover did insist that at least one of us is present at any given time, as he might have to make some amendments during the work and that is pretty much all you are there for.
Pic 3 Showing the scale, Nils is 6 ft tall. We can't stand here anymore....

After everything was done, the only thing we still had to do is built the dam for our overflow. We used some of the clay that was unearthed during the excavation and so far the dam has held and the overflow is working perfectly.

When designing an overflow it is important to try to slow the water down to prevent erosion. Making the overflow too narrow and too steep will cause the water to rush over in a large rain event and take with it a little bit of earth and soil every time. After a while the overflow will break down. It does pay to grow some plants with good fine root structures right on top of the overflow and possible cover the top with some stones.

Pic 4: North-East view of our summer pond and densely growing slope

So I hope to have given you some ideas on how to design your pond and maybe this year you will decide to incorporate such a multi functional and beautiful piece of landscaping into your own site.
Since it is mid winter (the coldest day of the year with -40C with the windchill) as I am writing this I will now lace up my skates and enjoy some of that good Canadian culture....on my private skating rink. 

Pic. 5 Fun

Yet another function of a pond in your backyard.


  1. Very nice pond. What are the dimensions of it?

    1. Thank you. The dimension are approximately 80'x45' the depth is 6' at the deepest point.

  2. Thanks that's a really decent size. We are looking at putting a large pond onto our land in Bulgaria. I have been looking high and low for examples. Yours is by far the best I've seen to what we want. Will be hard work because it'll all be done by hand... gulp..