Published: 22 Jan 2020

A process to improve the long term performance of the Temuka Oxidation Ponds has started this week.

The approximately $500,000 project to desludge the pond has begun following pre-Christmas earthworks to enable the collection and dewatering of the material.

Timaru District Council Acting Group Manager Infrastructure, Erik Barnes said that the process was a lot more complicated than many people would realise.

“For a wastewater treatment plant the desludging process isn’t as simple as just backing a truck up to the pond and sucking the material out, like you would with a home septic tank,” he said.

“Getting the material out of the ponds is only the start of a process that can take more than a year to complete.”

Planning work for the project, including investigation of desludging options has been taking place since 2018. This process was chosen as an efficient and cost-effective way of undertaking the job.

The process begins with the removal of the material by a dredge on the pond, the mix of water and sludge removed by the dredge is pumped into special geotextile dewatering bags.

These bags are made from a special material that allows the water to escape while keeping the solids contained. Once full, the bags will be left on-site in a fenced area to slowly dewater before finally the solid dry waste in the bags is disposed of.

All the water that comes out of the bags is then returned to the pond to be further processed through the wastewater treatment plant at Seadown.

“While the initial pumping of the waste can stir the contents of the oxidation pond up a bit and make it smell a little more than usual in the short term, the desludging bags won’t cause any smell,” said Erik.

“This is a major piece of work that will allow us to renew the Temuka Oxidation Pond, increasing its capacity back to what it was when first commissioned.

“For Temuka residents this means that once the work is completed there should be no, or at least significantly fewer, times when the pool causes a smell over the town.”

Last updated: 24 Feb 2021