The vastly smaller project that is the subject of this post is the construction of wicking beds with the recycling of used 200 litre oil drums. The principle is basically that of a self watering pot, whereby a water reserve is created in the bottom of the barrel and the soil 'wicks' the moisture up to the plants, or the plants send their roots down into the reserve.
Construction is a messy process and one needs to be very thorough about it to remove all traces of residual hydrocarbons to avoid soil contamination. Firstly the drums are cut in half with an angle grinder, drainage holes drilled around the girth and sharp edges and burrs ground off. Cleaning is done with a rinse of petrol and a good wiping out, followed by a blast with a high pressure water cleaner and an off the shelf, biodegradable detergent. This all needs to be done somewhere you can either trap the runoff and dispose of it properly, or where the chemicals can be biodegraded over time and away from water and food sources.
The rest is pretty simple: Fill up the halved drums with a locally quarried drainage gravel to within 20mm of the drainage holes with a small PVC pipe for checking water levels and topping up when needed. I've yet to get around to the next step, which is laying down a couple of layers of old shade cloth, filling up the drums with a good soil/compost mix and planting them out. We also have another four drums to cut in half, clean and install to complete the array.
You'll note I've also fitted a ring of 5mm garden edging to the top as a safety measure. This will also keep mini greenhouses held in place for colder or wetter times. Part of the soil mix will also be a handful of biochar (very pure charcoal used as a soil amendment) to help microbial activity along. Future posts will detail a few of the methods I'm using to make this new 'black gold.' So these drums that once contained hydrocarbons will soon contain this form of recalcitrant carbon that can resist decay for 10,000 years
The finished design will have five rows of four these beds accessed with recycled brick steps and sandstone masonry tailings running down either side. All-in-all a colourful mini monument to how our thirst for fossil fuels can be inverted to a hunger for good, locally produced, organic, healthy food.