Crunch time looms on Gisborne's wastewater

Wetlands trial shows great progress but questions remain unanswered.

Wetlands trial shows great progress but questions remain unanswered.

Gisborne wastewater treatment plant. File picture

REDUCING the amount of land needed for a wetlands system is one of the major challenges facing Gisborne District Council as it moves towards a crunch decision on how the city’s wastewater will be dealt with, a decision that must be made by the end of this year.

The wastewater management committee was told the wetlands trial, that will save the district millions, is proceeding well.

But a decision on whether it can be used has to be made by December when the council must apply for the renewal of its consent to use the outfall pipe.

Committee chairman Bill Burdett said it was important the committee — which has dealt with the issue for the past three years — made a recommendation to the council although not all of them might be there after next month’s election.

Council strategic planning manager David Wilson said a recommendation was due from the wastewater technical advisory group in November.

Mr Wilson was giving an update on the trial of the wetlands system, which he said was going well.

If the council was not able to use the wetlands the alternative would be an lamella clarifier — a system used widely throughout the world. The clarifier removes the solids and produces an organic sludge high in nutrients, which can be used as a soil conditioner. It is small and would fit in at Banks Street.

No indication of costs

He declined to give any indication to the committee of the potential costs of either system.

“We are not going to give you costs while we are trying to refine them.”

Asked what area of land would be needed for a wetland, he estimated it to be between 50 and 60 hectares but staff were trying to reduce that.

Turanganui iwi representative Ronald Nepe said that was about the size of Gisborne Park golf course. Mr Wilson said as a comparison, the airport occupied 90 hectares.

Amber Dunn said the wetlands did not need to be in one continuous area. It could cover several sites.

Mr Wilson said one of the issues with cost was how far the wastewater would have to be pumped. It could be between four and eight kilometres.

He acknowledged that the land within that distance from the Banks street sites potentially included good cropping land.

It was encouraging that the plants in the wetlands trial had come through the winter well.

Winter a difficult time

Winter was the most testing time because reduced sunlight and storms could have an effect on the ability of the plants to remove viruses.

The trial determined how successful the wetlands were at removing viruses. Viruses coming through were at very low numbers.

Amber Dunn pointed out this had not been a normal winter. It was drier and warmer than usual.

Mr Wilson said the water quality of the trials was above the level for bathing.

“You could swim in it,” he said.

It was intended to have parts of the wetlands area open for recreation but the main treatment area would have to be fenced off because the water would not be fully treated at that stage.

Roger Haisman said previous testing showed that up to 96 percent of the human DNA had been removed from the water by the biological trickling plant.

The purpose of the wastewater management committee was simply to make sure the conditions of the resource consent for the pipeline were met.

Mr Burdett said the committee had worked well in the past three years and he praised iwi representatives and committee members for their contribution.

REDUCING the amount of land needed for a wetlands system is one of the major challenges facing Gisborne District Council as it moves towards a crunch decision on how the city’s wastewater will be dealt with, a decision that must be made by the end of this year.

The wastewater management committee was told the wetlands trial, that will save the district millions, is proceeding well.

But a decision on whether it can be used has to be made by December when the council must apply for the renewal of its consent to use the outfall pipe.

Committee chairman Bill Burdett said it was important the committee — which has dealt with the issue for the past three years — made a recommendation to the council although not all of them might be there after next month’s election.

Council strategic planning manager David Wilson said a recommendation was due from the wastewater technical advisory group in November.

Mr Wilson was giving an update on the trial of the wetlands system, which he said was going well.

If the council was not able to use the wetlands the alternative would be an lamella clarifier — a system used widely throughout the world. The clarifier removes the solids and produces an organic sludge high in nutrients, which can be used as a soil conditioner. It is small and would fit in at Banks Street.

No indication of costs

He declined to give any indication to the committee of the potential costs of either system.

“We are not going to give you costs while we are trying to refine them.”

Asked what area of land would be needed for a wetland, he estimated it to be between 50 and 60 hectares but staff were trying to reduce that.

Turanganui iwi representative Ronald Nepe said that was about the size of Gisborne Park golf course. Mr Wilson said as a comparison, the airport occupied 90 hectares.

Amber Dunn said the wetlands did not need to be in one continuous area. It could cover several sites.

Mr Wilson said one of the issues with cost was how far the wastewater would have to be pumped. It could be between four and eight kilometres.

He acknowledged that the land within that distance from the Banks street sites potentially included good cropping land.

It was encouraging that the plants in the wetlands trial had come through the winter well.

Winter a difficult time

Winter was the most testing time because reduced sunlight and storms could have an effect on the ability of the plants to remove viruses.

The trial determined how successful the wetlands were at removing viruses. Viruses coming through were at very low numbers.

Amber Dunn pointed out this had not been a normal winter. It was drier and warmer than usual.

Mr Wilson said the water quality of the trials was above the level for bathing.

“You could swim in it,” he said.

It was intended to have parts of the wetlands area open for recreation but the main treatment area would have to be fenced off because the water would not be fully treated at that stage.

Roger Haisman said previous testing showed that up to 96 percent of the human DNA had been removed from the water by the biological trickling plant.

The purpose of the wastewater management committee was simply to make sure the conditions of the resource consent for the pipeline were met.

Mr Burdett said the committee had worked well in the past three years and he praised iwi representatives and committee members for their contribution.

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