Wastewater is back again on this council agenda. It’s that important I wanted to write something separate from the what’s going on in council piece.
Our Wastewater Treatment Plant currently gets rid of 96% of sediment but there are still large amounts of bugs present in the final product. The 4% left over makes the final product cloudy, which causes issues when trying to get the bugs out.
The staff recommended option is to investigate the feasibility of a wetlands. GDC has been running a very successful wetlands trial. In the trial, the cloudy 4% is removed by plants and the bugs that were present die from exposure. Wetlands has the possibility of being scalable depending on where it goes which is good for population growth.
To establish a wetlands will cost $12-$15m. However, it will need to have significant infrastructure in order to get the wastewater from the treatment plant to the wetlands which comes at a significant cost to council and ratepayers. The extra costs are an estimated $26-$49m on top of the cost to establish a wetlands. This is a one off infrastructure cost. The only ongoing costs would be establishing more wetlands and the upkeep of the pipe going out there.
There are possible pathways to bring that cost down but investigation into those options require community consultation and a lot of work. Which is why I support the investigation into the feasibility of the wetlands project.
If we decide to not do that then there is a possible mechanical option for treating the final product. With mechanical treatment we have to get rid of the cloudiness in order for the bugs to be killed. The cloudy sediment will stop any UV treatment from killing in bugs in the water. We have to clean the final product with a clarifier, which comes at a cost of $28.5m, in order to be able to UV treat the wastewater, which comes at a cost of $800k. Something that is not factored in is the cost of discharging through the marine outfall pipe and also the cost of disposing the sludge created which is collected and disposed in a separate process from the other 96%. We are limited on scalability options with mechanical treatment. If our population was to grow then we would need to more land near the treatment plant, another clarifier and another UV filter all at a cost.
There is no ‘do nothing’ option. Council are required to make a decision at this council meeting otherwise we will be in breach of our consent conditions. This will lead to fines, which is wasted ratepayer dollars and we would still have to do something. Even council has to follow it’s own consent conditions.