To get approval for the house we had to get a Land Capability Assessment (LCA) done – a survey done by an engineer including soil samples to determine what type of water treatment is required, and what the water distribution field should look like – size and method.
The engineer who did our LCA determined that a standard septic system would not be adequate for our circumstances and that we would need a secondary treatment system. He evaluated an Aerated Water Treatment System (AWTS) versus a Low Pressure Effluent Distribution System (LPED) and concluded that an LPED was most appropriate for us as we were offgrid. To an extent, he was correct – while all the aerated systems claim to be very low power, in an offgrid context, they are not – a 60W blower running 24 hours uses around 1.5kWhr. And they need maintenance every three months, chemicals etc. So on the surface an LPED seemed reasonable – lower maintenance, lower power.
Turned out to be a big problem, as no one installs LPEDs in our area. Like no one – too hard to install, too hard to design. We were stuck.
Luckily our neighbour has just built an offgrid house and he installed a sand filter as the secondary treatment option with a standard water distribution system. This feeds the outflow of the septic tank into a really large sand bed (think swimming pool size) which houses additional microbes to munch up the waste before distribution. Very low maintenance, low power. Perfect.
We checked with the engineer and council and they were happy for us to go down this path. Unfortunately, the EPA now need to approve the use of every sand filter, so an extra layer of bureaucracy, but the permit eventually came through. We used the same contractors as the neighbours – Valley Septic. (I believe they are spending heaps at the moment trying to get certified so that their standard designs don’t have to do this).
They have been brilliant – really easy to deal with, good relations with the council, approval couldn’t have gone better, nor could the installation.
The system was installed this week, in a day. We met them on site at 6:45am to sign off the installation location and discuss where the soil they dug up was going to go. The defendable space on the entire south side of the house where the system was going was a mess – a really large tree stump still in the uneven ground, and lots of buried roots.
We had intended to get our ground works contractors in before they arrived but the weather had been too wet, and Valley Septics told us not to bother. They removed the stump themselves, and landscaped a clay bank at the back of the shed for us creating a gentle slope instead of a drop off and covered it all with topsoil. I guess they had to put the clay and topsoil somewhere, but they put it exactly where we needed it. And marked out all the ground that has stuff buried in it so we don’t damage anything with heavy equipment. Cost well under $20k.
They’ve saved us thousands on earthworks and done a great job from start to finish. Brilliant. Couldn’t be happier.
Can’t wait to use it!!!!
Off Grid Living - Building the Dream 