Septic Tank


Not a very exciting topic, but it sure took a large amount of unintended effort. When the property was purchased, we had no idea that somewhere that was destined to be connected to the NBN was not connected to sewerage. The next surprise was that there would be no riser or connection to the tanks for emptying — you would have to dig almost four feet to expose the lids, which would happen every four years, yet nobody had the courage to put in a riser or discontinue the silly practise of refilling the hole. (Multiple times as the house was built in 1992).

And so it came to pass... One day in the mail the Onkaparinga council requested the occupant expose the septic tank lids prior to emptying. If this was not done, and there was a leak, or similar terrible event, then you would be charged, however, if you did expose the tanks, no further harm would befall you and there would be no charge — all this was part of the annual rates. Okay, so where is this tank? The drawing that we eventually obtained from the council appeared to have been drawn in a hurry, perhaps by the plumber's child, or to the council's liking. They could not tell exactly where this 30,000 litre tank was, but it was about 1,5 metres below the surface. It was also in the back garden. (The plot is almost 1000 square metres, so not that helpful. After witnessing the efforts of the graffitti artists working for the NBN a few months later to try and direct those who came after them on where to dig or lay fibre optics, there does not seem to be decent GIS for McLaren Vale).

After speaking to someone who made a living out of hunting for septic tanks before he retired, it was suggested that the two concrete castings would be a good starting location for the archeological dig. He previously offered to build risers, but the owners often declined due to expense. He simply refilled the hole with soft sand temporarily saving them $200 (admittedly not as deep down).

The septic adventures are split up into the archeological dig, with a breather waiting for the council to empty the tank. They notified me when I was overseas, so there was a reprieve to expose the lids as my wife was not going to take on the dig. She was as surprised as I was that we owned a septic tank. After the tanks were emptied, the futility of having inspection holes with 150mm pipes became obvious, as the pumping truck pipes were not ever going to fit down those holes. I decided that I was never going to repeat the dig, or pass on this disservice onto someone else, so a riser would be installed. Without going too much into the dead-ends about what can or cannot be done, we continue...

After the exposure, the hole had to be widened to make way for a riser as no information could be extracted from anyone as to the load capacity, where to buy precast risers, tank diameter for fitment, etc.

And so the mausoleum was started. If nothing else, it might make a good wine cellar or burial chamber. Perhaps this is how the pyramids were started?

Marker for septic tank location

Photo taken shortly after purchasing the house. The weeds were taking over as the lady who sold the house was in her 70s and in no condition to work in the garden. We said we would dig it all over once we had bought it, and have a vegetable garden. The concrete markers happened to slip into the photo by accident.

About 90° to the left, with the markers on the left of the photo.

Digging over the back garden

The weeds were dug in, and mulch was put over the top. Once it rained a bit and the ground was a bit softer, the soil was turned again. I noticed different soil between the markers but never gave it another thought. It is actually visible in the original high resolution photo before reducing this to 400 pixels for posting.

The start of the dig

A good place to start the dig, as was done many times before (since 1992).

So there you are

The septic tank had been reached before too long. Indeed, about 1,5 metres down. We were told to expose two lids, so we did. Not sure what to do about the unstable bank or what sort of liability there would be, but the person who was tasked with the lid opening and tank emptying was very pleasant. A ladder was provided and the job was done within an hour. The pipes were washed off with a garden hose, lids replaced, and the large mechanical dung beetle truck headed off with its load of crap. We now had four years to set about building a riser, or to make something that would not fall down (or collapse into a pit of guana).

Septic tank lids exposed

Part 1

The riser construction took a while and was interleaved with other projects. It was never part of any renovation plan, however, it had to be done. There are a number of photos, so to make the downloads less tedious, the construction was split into two parts.

The first part is here.

Part 2

The second part is here.