Waimate Oxidation Ponds to Undergo Waste Removal

Work to desludge the Waimate oxidation ponds (also referred to as sewage ponds) is now underway, with the process set to improve the ponds’ long term life and performance.

The desludging project aims to remove in excess of 500 tonnes of sludge from the base of the two ponds, a cleaning process that hasn’t taken place since their construction some 20 years ago.

The project, which once complete will add a further 30 to 40 years of capacity to the McNamara Road site, was first identified last year, following a sludge survey carried out by independent contractors.

As part of the project brief, the vast majority of the sludge will be removed.

Waimate District Council Asset Group Manager Dan Mitchell said all residents in the area had been spoken to directly by Council, but warned the initial pumping of the waste may create some unpleasant odours “from time to time”.

“Some days may be worse than others depending on the direction of the wind, but (aside from that), there will be minimal disruption to residents as the work gets carried out,” Mitchell added.

“Typically though, there should be no adverse odours in excess of normal operations.”

The process will involve the initial removal of the material by a dredge on the pond, with the mix of water and sludge then pumped in to geotextile dewatering bags.

The 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 the solid dry waste in the bags is then disposed of.

The water that comes out of the bags will then be returned to the pond for further treatment through the wastewater treatment plant.

Work is scheduled to be complete by early April.