Why is there a loading rate for a raised bed?
The OBC require that the mantle area for a raised bed or a filter bed be designed for a specified loading rate. The OBC sets a loading rate to prevent effluent break out from the sides of the leaching bed or mantle area where difficult soil conditions exist. It has been the experience of enforcement agencies that the construction of raised beds and filter beds under such conditions may require that the mantle area be extended for more than the 15 metre minimum.
