Last summer, after a lot of pondering, we decided to build our little pond.
We built it small (an oval pond about 7 metres in length, 4 metres in width at the widest point) mainly because of space limitations - the pond is located in a 15-metre wide strip at the bottom of the property.
Water comes from one branch of the U-shaped gravel drain (which goes around the house at a depth of c. 1 metre), as well as from the overflow of the underground rainwater cistern fed from the roof gutters (will come back with details on this).
The terrain is mildly sloped, so we had to build a dam. The soil is heavy clay, hence we didn't need to use a membrane.
We hired a man with a small excavator, who had worked for us on other projects and had some (rather limited) experience with ponds. In fact, he told us about ponds he built for clients in the area which eventually did NOT hold water! I figured out that he had no theoretical foundations for how to go about building the pond, so the failures that he mentioned were probably due to both him and his client being clueless...
Luckily, he was (kind of) good at following instructions.
The machine was too light for achieving good compaction, so we used a small road roller to pack the bottom and the dam (sadly, I discovered I have no pictures of the roller at work!).
And now about the mistakes that in retrospect I realised we made:
- we could have made the pond twice as big (=longer pond) - the amount of water through the French drain and the gutters would have been more than enough !!
- I said earlier that the operator was okay at following instructions - yes, just okay, not great; despite my repeated insistence on a milder slope for the sides of the pond, we still ended up with sides that are a bit too steep
- because of the steep sides, we did a less than perfect job at compacting them - we had to rely on the light-weight excavator alone as the roller couldn't get onto the steep sides
- I underestimated the extent of settling of the dam. Six months after we built the pond, the dam settled about 20 centimetres below its original height. I don't think this was because of insufficient compaction - we were very thorough in compacting the dam as we built it (the roller went over it a dozen times for every 25-30 cm of earth that was added). As a consequence of settling, the dam is now 20 cm below the level of the back of the pond. This is slightly disturbing visually (back of the pond higher than the front). I will have to remedy this by adding a few inches of clay on top of the dam - I will do this with a wheelbarrow and shovel (I've already set aside some earth obtained from another excavation).
... So that's it for now.
Comments, critique, and suggestions will be appreciated !
Great pond and thanks for sharing! The steep sides stood out to me but you already addressed that. The other thing is personally I like ponds with more complex edges instead of a simple geometric shape. I like little shallow fingers, etc. These can provide habitat and just more overall complexity which tends to promote more biodiversity. But I do like the pond and I'm planning on making some similar ponds on my property and it is great to see what other people are doing on their land!
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