How much Crushed Rock?
Trenches are generally dug about 600mm deep and require approximately 500mm of crushed rock and then 100mm of soil on top. 50mm of crushed rock goes in the bottom of the trench, then the pipe, then another 450mm of crushed rock on top of the pipe. To calculate how much you need simply multiply the length by width of trench by the desired depth of material. The width of the trench will be about 25mm wider than the width of your bucket. Note: it is important that all dimension used are in metres. There are a variety of crushed rock types and sizes available. Talk to your garden supplies. 12mm scoria was used for this project.
