water assurance: sewage treatment

It is very important to ensure that natural reserves of underground water do not become polluted.  The Norfolk Island water assurance scheme was built to protect this valuable resource.  It is located opposite the Waste Management Centre, on airport land.

The water assurance plant treats all the sewage from about 50% of the island’s population but only collects from about 10% of the land area.  The parts of the island which are connected to the water assurance scheme are from the school. Down through Burnt Pine to the Waste Management Centre, along much of New Cascade Rd and so includes most of the large tourist accommodations.  In addition, when septic systems are pumped out anywhere on the island, the effluent also goes to the sewage plant.

The sewage is treated in a secondary treatment plant.  The first step is primary treatment where the sewage is sieved through a grid and then the suspended solids settle to the bottom of a settling pond.  In the secondary treatment, the liquid is trickled over rocks in a big pond.  The rocks are covered in bacterial sludge which digests the sewage, removing lots of the nutrients.  The water that is left is pumped to an outfall into the sea on the west coast near Headstone.

A secondary treatment pond