Negotiations over ponds
RACHAEL KELLY Only 10 per cent of the sludge in Gore’s oxidation ponds has been removed and the Gore District Council is in negotiations with the contractor it engaged to carry out the work.
Removal of the sludge in the ponds was scheduled to begin in November 2016 by North Islandbased company Hydracare, after the contract for the work was awarded in September 2015.
Work at the ponds has now stopped, but council chief executive Stephen Parry and Gore District mayor Tracy Hicks said in an emailed response to questions from Newslink that the council and Hydracare are in negotiations and it would be ‘‘inappropriate to comment at this time’’.
Hydracare has also declined to comment.
The project was expected to take about five months, but the council said on Monday that only 205 tonnes of dry sludge had been removed from the ponds.
The project budget was $2.6 million and $478,175 has been spent to date.
The sludge is removed in a liquid (slurry) form using a dredge. It is then processed through a primary dewatering unit that creates approximately 20 per cent sludge, which looks like wet soil. This sludge is disposed at the landfill.
The volume of Gore’s two oxidation ponds is about 240,000m3.
That is the equivalent of four Olympic sized swimming pools, council said in a press release in November 2016.
At that time council project manager Sam Bunting said ‘‘the main pond is presently at about 30 per cent capacity, which is when they lose their ability to start to treat the wastewater.
‘‘Consequently there is a greater risk of odour issues and a decline in the quality of our discharge to the Mataura River.’’
It was the first time in 46 years the oxidation ponds had been scheduled to be cleaned out.
Removal of the sludge was predicted to increase the capacity of the ponds and improve wastewater treatment.
Desludging work has stopped at the Gore District Council’s oxidation ponds.