Gunnedah Shire Council is pushing ahead with design plans to upgrade the town’s ageing sewerage system – a project which could cost almost $24 million.
Meanwhile, new options are being sought to dispose of the treated effluent after it was revealed the existing Gunnible North farm where wastewater is sold, may no longer wish to continue the arrangement.
Gunnedah councillors were told the existing sewerage filtration infrastructure is nearing the end of its useful life and would require replacement in the next 10-15 years.
Gunnedah Shire Council manager of water services Michael Ludlow said the decades-old ‘trickle filter’ technology currently in operation at the sewerage plant has been superseded and a more modern approach is required.
“(These) filters have been around for years and have done a great job for us,” Mr Ludlow said.
“But it’s old technology, and it doesn’t cut the mustard with the EPA (Environmental Protection Agency).
“I think the last trickle filter that went in in NSW was 1992.”
Instead, councillors agreed to begin preliminary design and investigations associated with a new Intermittent Decanted Extended Aeration (IDEA) process plant.
This design – which council has initially budgeted $580,000 in approved funds for the 2025-26 financial year – will allow council to pursue grant funding for the design and construction of a new plant.
While this is happening, council will explore other options to dispose of the treated effluent such as for use by nearby farms and in dust suppression in the mining industry.
Under existing arrangements, Gunnedah’s treated sewerage travels along a 10-15km pipeline on the Namoi River to the farm Gunnible North which is operated by IAI Australia.
The Effluent Reuse Scheme was established in 1998 and is the preferred avenue for wastewater disposal as existing infrastructure is already in place and council receives payment for the water discharged.
But in recent times, there has been less certainty about continuation of the agreement with Gunnible North.
“When we first went in it was locally owned, but it has been sold twice since then,” Mr Ludlow said.
He said the new operators do not have the same “personal investment” as the original owners and that was reflected in the payment negotiations.
“We did a pretty good job and increased the money they’re paying but they wanted some concessions which we agreed to,” Mr Ludlow added, but he did not divulge what those concessions were.
Gunnible North’s acceptance of the treated wastewater negates council’s need to discharge treated wastewater into the Namoi River which would incur a significant surcharge from the EPA.
Hypothetically, if the wastewater taps were turned off at Gunnible North, this would leave council with nowhere to pump the treated water except back into the Namoi River.
This would result in council’s EPA licensing fee increasing from $3650 per year to more than $60,000.
Other options considered by council in previous years such as pumping the treated wastewater onto playing fields were considered cost-prohibitive due to the high level of water treatment required.
Gunnedah Shire Council manager water services, Michael Ludlow.
Mr Ludlow explained the Gunnedah’s IDEA plant upgrade would provide the foundation for additional water treatment options, should the Gunnible North effluent arrangements discontinue.
“We’re going to put all the infrastructure in place in case that agreement fell over,” Mr Ludlow said.
“They only need to give us 12 months’ notice.
“We have to have a plan B.”
Councillor Robert Hoddle successfully sought an amendment to council’s plans, that in addition to design for an IDEA plant which was considered a necessity, that it also investigate alternative options to Gunnible North for effluent discharge.
He suggested the treated wastewater should be offered to farms in the Gunnedah area first and was aware of several in the area which were eager to learn more about the process.
“I believe that water needs to stay here,” Cr Hoddle said.
“There are five large farms here that would like to know more … to have the discussion.”
The councillor and local citrus farmer understood local government areas such as Tamworth and Armidale use sewerage for its own irrigation and asked if Gunnedah council could do the same.
It was agreed that Gunnedah Shire Council would simultaneously pursue both the design for the IDEA plant and alternative options for the wastewater disposal.
The council resolution said an investigation would be undertaken into other uses of surplus water that would benefit the community, including:
a. What method other councils use to dispose of wastewater and how efficiently their schemes are working. Especially Armidale, Tamworth, Narrabri.
b. Determine what interest there is from local farmers to take the water for irrigation.
c. Determine if the coal industry is interested in taking the water for washing coal and dust suppression.
In Brief – Gunnedah Sewerage Treatment Plant was originally constructed in 1938 and has undergone numerous upgrades.
It was augmented in 1968 when a parallel trickling filter process stream was added.
In 2018, the Gunnedah STP Stage 3 upgrade was completed, which included installation of a new inlet works, anaerobic digester and sludge dewatering facilities plus decommissioning of redundant assets.
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