Greening the Septic System

A guiding principle of permaculture, my preferred gardening method, is to avoid waste wherever possible. Of course the definition of 'waste' may be a point of contention, but in this instance we are defining waste as any unused outputs of the system. For example, the absorption trench receives the excess from the septic tank, which in turn takes the waste water from the toilet/showers/kitchen in the house (see diagram below). If this water wasn't used then it would fit the definition of waste, however there is a way we can use it...

Obviously it would be preferable not to use this water directly, water borne diseases still account for a lot of misery worldwide, so the plan is to ‘filter’ the water through living plants. Essentially plants will be planted in this area, such as comfrey, tree lucerne, pigeon pea, etc, which will take up this water and turn it into foliage. We can then cut this foliage for forage (tree lucerne leaves are approx ~22% protein with up to 81% digestibility) or for mulch. Either way we are capturing that water (and nutrients) that would otherwise be lost.

The plan to achieve this goal is to initially revegetate the absorption trench area with green manure plants (in this case we are using red & white clover, barrel medic, alfalfa and millet) to initially improve the soil, and to begin to break up the hardpan. We will then follow up with some deep rooted perennial ground covers such as comfrey and daikon radish, and finally plant out the canopy species such as tree lucerne. This is a fairly long term objective, as the tree lucerne seedlings won’t be planted until after the last frost 2010.

The video below outlines our initial steps...

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