South Canterbury

Image by Makalu from Pixabay 

A client from South Canterbury, 60km inland from Timaru in the South Island, approached us looking for a sustainable wastewater treatment system to complement the sustainable house he was building.

He wanted a system that would allow his wastewater to be used as a resource: water for irrigation and compost for the garden. He also wanted a system with few moving parts because of possible winter power outages.

This site is located in a rather dry place with hot summers and severe winters with snow on the ground. Here water for irrigation is often scarce. Our client reasoned his wastewater could be used to irrigate his garden. We agreed and saw the garden as a great way to recycle wastewater back into the environment.

The building site for this project was tricky with a seasonal water table that can rise to within 100mm of the ground surface. We believed we could put a design together using an Autoflow system that would cater to our clients needs.

Two years ago our client installed his Autoflow system. The Autoflow tanks were buried in the ground as it was a level site. A small pump was used to pump the wastewater from the last tank, the batch reactor, to the dispersion field. To create separation of the wastewater from the ground water, a raised mound was created from soil excavated from the house site. The dispersion field was buried in this mound and native grass planted to enable transpiration (plant take up) of the wastewater.

The South Canterbury finished Result

Two years on our client’s waste water system is running beautifully. The planted mound has become an attractive feature on the north side of the house. The grasses have grown vigorously from the daily doeses of wastewater they receive. The mound also serves as a wind break against the preailing north westerly. Our client has yet to dig out the compost from the vermi tank as his worms are thriving eating everything they are fed from the toilet and kitchen.