In order to clean the pond, we dig a canal first. © Alexis Rowell
How do you do keep the trees and plants on a permaculture farm watered given global warming? Alexis and Blanche got busy with a digger to make a rainwater storage facility and a natural swimming pool.
We’re going to need to store a lot of rainwater at La Grande Raisandière (The Big Raise), our permaculture farm in the Perche region of France. In permaculture one is supposed to design out the fossil fuels, animal energy and physical effort as much as possible so as to produce more with less. So instead of using costly tap water which is cleaned and pumped, we want to use rainwater for watering our forest garden as summers become drier due to man-made climate change. The water in our pond also enhances biodiversity and attracts species such as frogs and swallows, which will eat insects that attack our crops. Plus, of course, if the pond is deep enough and clean enough, we can swim in it!
When we bought La Grande Raisandière, our one pond, although beautiful, was mostly full of mud. Our neighbour Louis said it had never been cleaned in his lifetime so that takes us back to the Second World War. Plenty of fish live in it though: hundreds of roach, a small, silvery, freshwater fish who do synchronised swimming sequences to Olympic standards! So we decided to clean out and deepen the pond, whilst protecting as many fish as possible.
First of all, we had to find out how far down we could go without piercing the clay layer which holds the water in the pond. It turns out that we have “limon” soil (decomposed organic matter) from 0cm to 70cm and then clay from 70cm to 3m60, so that gives us plenty of margin for error. We’ll spare you the story of how we excavated the test holes, but it’s here if you’re interested.
Since one of our aims was to create a natural swimming pool, I contacted some specialist companies, but they only wanted to create closed loop, fake-natural swimming pools they can control (which means no trees around them shedding nasty, dirty leaves) and they wanted silly money (tens of thousands of euros).
A word about fossil fuels. Our aim is to create a permaculture farm which uses no fossil fuels and which therefore doesn’t contribute to manmade climate chaos. But in the design phase we’re having to make some compromises. Even the great Sepp Holzer, an Austrian and one of Europe’s foremost permaculture farmers, uses a digger from time to time. (See here for how he seals ponds by using a digger to mimic the vibration of pigs wallowing in mud!!!)
Stage 1: Digging out the evacuation canal
Being trainee maker-farmers, we decided to deepen and clean the pond ourselves—with the help of a diesel-powered digger, digger operator Jean-Michel and a tractor-lorry operated by Mehdi. Total price: €4,800—not cheap but a fraction of what the natural swimming pool experts wanted.
First of all, we deepened the overflow canal to create a storage facility for the water and the fish. That took a day and a half of mechanical digging. At 3pm on day two we opened the barrage between the pond and the canal and watched the water slosh in.
Stage 2: Moving the water and the fish
The fish were a bit reluctant to move at first, but they mostly got the message when it became clear that the pond was emptying fast. That evening, I spent two hours running around with a children’s fishing net trying to save any stranded fish!
Stage 3: Dredging the pond
Once the pond water and fish had been transferred to the canal, Jean-Michel began dredging the pond. The mud was a metre thick in places so, as the photos show, there was a lot to remove.
Stage 4: Spreading the mud
This is 50+ years of decomposed leaves and twigs so it’s fabulous compost. The pond should now take three times as much water, but with the canal we will eventually have 6-10 times as much water as we originally had.
To complete the swimming pool, we continued the line and depth of the canal into the pond so we now have a 50m Olympic laps pool!
Stage 5: Filling the pond with rainwater
The gutters on the main house already direct the rainwater they catch into the pond via underground pipes. We’ve now installed guttering on the outhouse so that even more rainwater is diverted into the pond.
Stage 6: An additional source of fresh water
We have one other possible source of fresh water: our concreted-over well apparently goes down to an underground river, so I’m looking into whether we can use a solar pump to bring up water from it.
Our neighbours have offered us oxygenating plants from their pond which will help to filter the water.
So let’s see what our various sources of fresh water and the oxygenating plants do to the quality of the water. Now all we need is rain. Lots of it. Time to learn a rain dance!!!
See the previous columns of the maker-farmers
More on La Grande Raisandière website