DIY drainage swale using a reverse hugelkultur

FullSizeRender (8)Last year we had our our back yard cleared of invasive brush in the fall and then planted with low mow grass in the spring (some conventional grass seed as well, which I regret).  Over the course of the summer I couldn’t resist and put in my first attempt at at hugelkultur to house the many tomato plants that had seeded themselves around the garden.

This year I decided to take down the hugelkultur and put in a larger garden bed in it’s place.  It’s the one part of our yard that gets full sun but unfortunately it also has a bit of an underground stream flowing through it that becomes a problem during rain storms.

We got some HUGE quotes from local landscaping companies to deal with the drainage. Um, no thanks, I don’t want to spend 16k to make my back yard pretty! I’d much rather keep our money and just have a stream!

But then I started thinking about using a swale.  I’m kind of obsessed with permaculture but actually incorporating it into our landscape is an ongoing challenge.  Basically a swale creates a holding tank for excess water that will then slowly release into the land below.  Conventional drainage just moves the water away to the side of the yard or whatever.  This allows you to still USE the water for the garden!

I had made a small swale as part of my hugelkultur last year but it didn’t quite do the job. I decided to expand it to cover almost a quarter of the 20×10 garden space.

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I dug a hole about 18inches deep.  Deeper would have been better but getting through the clay and rocks was a challenge.  The water quickly filled the area, delighting my kids but somewhat frustrating me!

I tried my best to keep it in line with the grade of the slope.  I want it to really hold the water rather than just funneling it away.

While digging I was sure to separate out the topsoil from the lower levels of clay. The best part though was dismantling the hugelkultur and finding tons of worm castings and nicely broke down compost!  When I put it up last year I had said, worst case scenario it will be a big compost pile and I can use the soil for my new garden.  Score!

I decided to fill the trench with rotting wood.  In the same way that a hugelkultur uses rotting wood like a sponge to hold water above ground, this should do the same under ground.  Well, I hope it does…  I looked it up again in Gaia’s Garden to make sure my line of reasoning made sense and it seems like it should work!

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I just can’t help myself.  I LOVE the idea of a closed system where you just use what you make and make the things you use.  I’m REALLY far from that reality but I do have lots of rotting wood so I figure it’s worth a shot!

After I filled the trench with rotting wood I had a chance to see how it performed before covering it fully.  After a full day of spring rains I could see that it was holding a lot of water but some was escaping out the side.  I decided to go with that and create an overflow drainage ditch that is higher than the rest of the ditch so the runoff will go where I want it to.  I also caved and just bought a drainage pipe to use in there. I couldn’t figure out how to keep it open enough to move the water while also having it be just shallow enough to just catch overflow?  Maybe one of you knows?

I then filled in the crevices with some smaller sticks to help keep space for air and water.  IMG_0003

I separated out the dirt, soil and compost to rough in what will be the garden beds.  The local tree guys fortuitously called to ask me if I wanted more wood chips the week before so I used those to cover the swale and the garden paths.  They had pine, which apparently isn’t so great for plants but I’m hoping it will be fine since I’m not planting directly over it.

A traditional swale would usually have a raised mound directly down slope from the ditch.  I’m not doing it that way though. Sometimes I like to just half follow directions and see how it goes.  And when I say sometimes I mean usually.  But anyway, I’m hopeful it will work!

Next I covered the swale with wood chips which will serve as the pathways for the garden.

I also put in the beds.  I used large rotting logs to create the boundaries of the bed on the lower level of the garden.  I kind of love dragging big rotting trees from the forest! My hope is that they will help create a barrier for weeds, store extra water and break down over the next few years to eventually add more biomass to the garden. I was lucky enough to find a whole pile of rotted wood that crumbled into soil as soon as I picked it up. I filled up several wheel barrows with this and mixed it in with the soil I saved from digging the swale.  Again, rotting wood from around the property serves as a great free recourse!  And don’t worry, there is still PLENTY of rotting wood out there to feed the forest floor!

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Now all I need is to put in a fence and add some extra compost and amendments to the soil.  I’m planning to break down a few more rotting trees to enrich the soil too. I hope it all works!

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5 thoughts on “DIY drainage swale using a reverse hugelkultur

    1. What do you think kept it from working in your yard? So far it’s held out pretty well with a few heavy spring rain storms. There is still pooling in other areas of the yard but the garden beds faired well…

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  1. Hi. Thank you for sharing your project. What I did for rain that overflowed my hugelkultur drain trenches, was to make “fishbone” trenches along the main trench and fill in with Florida sea shells (could be lava or pebbles, but I’m using local Florida material). It has really helped with water issues and avoids the pipe.

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