On occasion, our two big water tanks at the very top of Milkwood Farm overflow. What to do with the intermittent extra water? It’s too precious to just drain away. Time to design a water catchment and planting plan to make the most of it.
Since solving this problem is both necessary and interesting, we decided to develop an intern project around it. The brief: design, implement and plant a system that makes use of intermittent excess water, shelters the intern camp and shed, and provides a useful yield. Go, you fabulous interns!
The water tanks in place, with the western slope below them in a particularly wet year (read: grass) January 2011.
Stepping back a bit, a word about our water tanks. At Milkwood, we’ve chosen to collect all the rainwater we need for our home via a big shed at the top of our ridge. The very big shed roof is connected to two very big stainless steel water tanks, and hence all the drinking water we need for the farm is gravity fed. You can read more about it here.
And so our interns Claire, Adam, Sabina, Jurgen, Olivier and Ashley set to work designing a system to make use of the occasional gift of excess water. The design brief included a short timeframe (4 days from start to end), and the use of what materials and plant stock we already had available on-farm.
It was decided to catch and use the runoff by creating and implementing a series of small swales which spilled one into the other, stepping down the western slope of our ridge.
These swales have rubble spillways to enable the runoff water to spill gently from one swale down to the next when the first one is full.
The plantings on the swales are firstly hardy pioneer species (mostly acacias), in order to get some biomass and microbiological action happening on this rather barren, exposed and rocky slope. Once these plantings are up and happy, we’ll introduce some other plantings inbetween.
Where the tank overflow meets the beginning of this swale system. The surrounding rockwork will help spread and slow the flow of water.
From this overflow influx, the water runs out along the first swale, before spilling gently into the next, and the next
It was great luck that as this project was just being completed, down came the rain, conveniently overflowing the tanks and testing the whole system. It was great to see everything working as it should!
The later plan is to create a sloping guild of useful, extremely hardy tree species, planted along these same swales. Perhaps something like Olives, Chestnuts and Paulonias. We’ll have to do some trials and see what works best, as this slope is west facing and gets a lot of hot summer sun.
All the swales are also planted with lomandra, a very hardy and useful plant whose roots will help hold things together in between the available water. And the end result will hopefully be a beautiful, sloping area, full of the promise of shade and possibilities.
A necessary task that needed to be dealt with to prevent future erosion and a great little design project, all in one. Cheers, all!
Many thanks to our great interns Ashley, Olivier, Adam, Claire, Jurgen and Sabina for their efforts in implementing this necessary feature of Milkwood. Thanks also to Adam, Olivier and Claire for the pictures.
Our next internship program is currently open for applications. More info here.
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Sunday, 23 October 2011
Top tank overflow: design + implementation « Milkwood: permaculture farming and living
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