Picture taken 2012
This is what Dave and I have been doing in our spare time - moving the 15-20 cms of silt which came down with the last flood. It's a combination of our neighbour's driveways (on the hill above) plus some of the back-fill we used building the retaining wall in the picture. It's rather unremarkable, simplistic and dare I say even tedious of all the tasks we do here...pick, shovel, load, cart and dump - yet it's a very important job too. Like the ants, termites and plethora of other insects which use the earth during their life cycles, we all have something in common: dirt is everywhere we live.
Our concrete driveway in the background
We can cover it in concrete or with gardens but soil is almost always on the move. It's part of the natural ecology. Rather than employ large machines to religiously deal with it for us however, we gladly embrace the working of the soil as part of our living ecology. For every load of dirt we shift, we get paid for in muscle mass. Traversing every footstep with monotony, we can see where dirt is best employed too. If a path is too steep or a hole in the ground too dangerous, our feet will tell us and so we move dirt where it's needed around the property
At present, it's behind the house, where we are building more buffer space for the surcharge of the building. It wasn't until the January floods (2011) we had to consider what impact the force of heavy rain could do to our house. Not only did it drench the soil to levels not experienced for over 30 years (causing it to compact tighter when it dried) but also the force of the amount of rain falling, put extra pressure on the house pad. It all resulted in the soil lowering.
Our house is in pretty good shape considering, but we've decided not to sit on our hands either. Ants wouldn't! We see them all the time after a storm, building their defences back up, raising the level of the entry hole to withstand the next big rain event. Likewise, we take the silt which got dumped on the cut side of our house, and move it to the fill side; expanding the dirt at the base of the house pad outwards. We will then plant it out with gardens too, but for now we are working on the edge.
After 3 days work
The edge of our batter is going to be a drystone retaining wall. Man these are wonderful things to build! When you've had to compact the road-base footings of a constructed block wall, with nothing more than the top of a heavy mallet (ouch, me back!) you will understand the pure joy of laying a drystone retaining wall, because the footings ARE the stones. All you need to do is expose the natural compacted layer of soil and start laying them down. Yes it can be fiddly at times, trying to find the pieces which match, but once you get going you seem to find them by intuition.
Still more rocks to lay
We've stepped the stones back (angle of repose) increasing the interlocking capacity to withstand the pressure of the soil behind it. That's why it's important to fill in every gap with chinks of stones, so that as a whole unit (large and small) every rock can interlock and buffer the surcharge. For those wondering, surcharge is just the term used to measure the weight above a retaining wall. It's how Engineers come up with the recommendations of minimum retaining wall heights, before Council certification is required. For our Lockyer Shire in Queensland, we can build a retaining wall without certification up to one metre high. Our drystone retaining wall is going to be well under that. Other Council regulations can affect whether you need certification, so be sure to check with the Planning Departing in your local Shire, before embarking on your own wall building project.
Back fill with smaller rocks ~ add organic matter ~ then plant!
But really every opportunity you can give the earth to reclaim it's vegetative cover, is a step towards preventing soil moving in the first place. The only real exception to that rule is floods! Not a great deal can stop a force of water, best practice is just to get out of it's way and clean up afterwards. If you're considering working your own piece of land, take some advice from a human earth mover, check out what your local ant colony is up to. See how they build their paths across a slope rather than up or down. Wish we had paid them more attention before we concreted part of our driveway. I'm sure if we did, we wouldn't have allowed a building company to decide how our land would be accessed or cut.
But you live and you learn and hopefully make more informed decisions in the future. While ants don't exactly come with engineering degrees, they certainly know a thing or two about the natural elements. We like our ants here. At times we've had to poison them (regrettably) when they've built a massive mound near accessing our cars or footpaths. I don't mind living with ants so long as they don't bight me on the way to the car! Thankfully, where we had to poison them in the past they have not returned to build there, so we no longer poison. We still see them habitating other parts of the garden and on our bush-walks around the area. Ants and termites are important to the echidna's diet in this area, and we see those occasionally in our garden too.
When you think about it, earth is something we all need in some capacity, even if it's just to give our feet something to stand upon. I couldn't see myself doing anything more enjoyable for New Years than playing with dirt.