Wetland the preferred option

Wastewater Committee grapples with treatment options and urges council to focus on affordable options for community consultation.

Wastewater Committee grapples with treatment options and urges council to focus on affordable options for community consultation.

Gisborne wastewater treatment plant. File picture

THE Wastewater Management Committee has settled on a wetland as its preferred primary recommendation for a further upgrade of the city’s sewage disposal system, and has urged the District Council to put affordable options out for community consultation.

The committee this week rejected three options for public consultation put forward by the council’s project team and instead went with proposals that originated from the community-based Wastewater Options Review Group (WORG).

WORG, established in December 2016 to investigate the best option to treat Gisborne’s wastewater, believes a combination of wetlands, high-rate algal ponds and habitat wetland would achieve all the technical goals required to treat city sewage.

The committee’s three new recommendations to go forward to the August council meeting were all based on a wetland proposal and the top two do not include a second biological trickling filter plant (BTF).

The rejected options put forward by the council project team included additional clarification and UV disinfection to the existing BTF plant in Banks Street at a cost of $23.5 million, a second BTF plant, clarification and UV disinfection at $34.5 million and a wetland proposal at $39.1 million.

The project team’s report said further cost analyses were under way in “whole of life costs and the impact on ratepayers”. That information will be tabled when Future Tairawhiti workshops the options next week.

Cost estimates for a wetland were based on the assumption that it could be located within 2.5 kilometres of the Banks Street treatment plant.

The report to the Wastewater Management Committee states the “do nothing further” option was not considered reasonable to take into a public consultation process.

“Doing nothing would be completely at odds with the resource consent in terms of cultural aspects, water quality standards and a progression towards the removal of treated domestic waste from the marine outfall.

“Doing nothing would be in breach of the resource consent conditions.

“Retaining the current treatment standards would mean Gisborne’s level of wastewater treatment would remain below par nationally.”

Yet the options originally put to the Wastewater Management Committee yesterday by the project team included “defaulting” on the resource consent for the city’s wastewater and continuing to discharge treated sewage into Poverty Bay through the outfall pipe.

“All the options include a discharge into the sea component because of the quite unique situation in Gisborne with usually low flows of water in streams and rivers in the city,” the committee was told.

“That makes it really difficult to discharge to waterways so the only option is a discharge into the sea.”

Wastewater Management Committee chairman Bill Burdett said there was lengthy discussion around both options but in the end the committee stayed with the original WTAG recommendations for public consultation.

“That does not mean to say the council will accept those recommendations before we get to the full council meeting, where final decisions will be made on which options are included in long-term plan consultation on August 17.”

Future Tairawhiti will discuss the consultation options further next week.

“Future Tairawhiti will make their own recommendations to the council, then the council will decide what options are put out for public consultation,” Mr Burdett said.

“It is the most contentious issue the council has ever had to deal with.

“When you combine it with the ‘Drain Wise’ project to upgrade the city stormwater system, the costs are horrendous.

“The Wastewater Management Committee hopes that common sense will prevail when it comes to an affordable set of options for the community to consider.”

The three committee’s three options were detailed in order of preference:

1. Use the existing BTF, add a clarification stage with solids handling, install additional redundancy measures, UV treatment and a 12 hectare polishing wetland, with continued investigation into alternative use and disposal (AUD) options and ultimately no more discharge of treated wastewater to sea. Also, that the new consent, or consent variation, would be for 10 years only, allowing for demonstration of the council’s commitment to the AUD process.

2. An amended option that includes use of the existing BTF, adding a clarification stage with solids handling, installing additional redundancy measures, UV treatment, a 12 hectare polishing wetland, wood chip denitrifying wetland and disposal to the outfall. Continued investigation into AUD options and ultimately no more discharge of treated wastewater to sea, and the new consent, or consent variation, would be for 10 years only, allowing for demonstration of the councils commitment to the AUD process.

3. To add an additional BTF to the existing plant, add a clarification stage with solids handling, install additional redundancy measures, UV treatment, a 12 hectare polishing wetland, wood chip denitrifying wetland and disposal to the outfall with continued investigation into AUD options and ultimately no more discharge of treated waste water to sea.

Also that the new consent, or consent variation, would be for 10 years only, allowing for demonstration of Councils commitment to the AUD process.

THE Wastewater Management Committee has settled on a wetland as its preferred primary recommendation for a further upgrade of the city’s sewage disposal system, and has urged the District Council to put affordable options out for community consultation.

The committee this week rejected three options for public consultation put forward by the council’s project team and instead went with proposals that originated from the community-based Wastewater Options Review Group (WORG).

WORG, established in December 2016 to investigate the best option to treat Gisborne’s wastewater, believes a combination of wetlands, high-rate algal ponds and habitat wetland would achieve all the technical goals required to treat city sewage.

The committee’s three new recommendations to go forward to the August council meeting were all based on a wetland proposal and the top two do not include a second biological trickling filter plant (BTF).

The rejected options put forward by the council project team included additional clarification and UV disinfection to the existing BTF plant in Banks Street at a cost of $23.5 million, a second BTF plant, clarification and UV disinfection at $34.5 million and a wetland proposal at $39.1 million.

The project team’s report said further cost analyses were under way in “whole of life costs and the impact on ratepayers”. That information will be tabled when Future Tairawhiti workshops the options next week.

Cost estimates for a wetland were based on the assumption that it could be located within 2.5 kilometres of the Banks Street treatment plant.

The report to the Wastewater Management Committee states the “do nothing further” option was not considered reasonable to take into a public consultation process.

“Doing nothing would be completely at odds with the resource consent in terms of cultural aspects, water quality standards and a progression towards the removal of treated domestic waste from the marine outfall.

“Doing nothing would be in breach of the resource consent conditions.

“Retaining the current treatment standards would mean Gisborne’s level of wastewater treatment would remain below par nationally.”

Yet the options originally put to the Wastewater Management Committee yesterday by the project team included “defaulting” on the resource consent for the city’s wastewater and continuing to discharge treated sewage into Poverty Bay through the outfall pipe.

“All the options include a discharge into the sea component because of the quite unique situation in Gisborne with usually low flows of water in streams and rivers in the city,” the committee was told.

“That makes it really difficult to discharge to waterways so the only option is a discharge into the sea.”

Wastewater Management Committee chairman Bill Burdett said there was lengthy discussion around both options but in the end the committee stayed with the original WTAG recommendations for public consultation.

“That does not mean to say the council will accept those recommendations before we get to the full council meeting, where final decisions will be made on which options are included in long-term plan consultation on August 17.”

Future Tairawhiti will discuss the consultation options further next week.

“Future Tairawhiti will make their own recommendations to the council, then the council will decide what options are put out for public consultation,” Mr Burdett said.

“It is the most contentious issue the council has ever had to deal with.

“When you combine it with the ‘Drain Wise’ project to upgrade the city stormwater system, the costs are horrendous.

“The Wastewater Management Committee hopes that common sense will prevail when it comes to an affordable set of options for the community to consider.”

The three committee’s three options were detailed in order of preference:

1. Use the existing BTF, add a clarification stage with solids handling, install additional redundancy measures, UV treatment and a 12 hectare polishing wetland, with continued investigation into alternative use and disposal (AUD) options and ultimately no more discharge of treated wastewater to sea. Also, that the new consent, or consent variation, would be for 10 years only, allowing for demonstration of the council’s commitment to the AUD process.

2. An amended option that includes use of the existing BTF, adding a clarification stage with solids handling, installing additional redundancy measures, UV treatment, a 12 hectare polishing wetland, wood chip denitrifying wetland and disposal to the outfall. Continued investigation into AUD options and ultimately no more discharge of treated wastewater to sea, and the new consent, or consent variation, would be for 10 years only, allowing for demonstration of the councils commitment to the AUD process.

3. To add an additional BTF to the existing plant, add a clarification stage with solids handling, install additional redundancy measures, UV treatment, a 12 hectare polishing wetland, wood chip denitrifying wetland and disposal to the outfall with continued investigation into AUD options and ultimately no more discharge of treated waste water to sea.

Also that the new consent, or consent variation, would be for 10 years only, allowing for demonstration of Councils commitment to the AUD process.

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Bruce - 2 months ago
This is crazy. The stuff coming out the end of the pipe is almost 100 percent human DNA-free. Spend the money on where the real problem is, raw sewage overflows into our rivers.

winston moreton - 2 months ago
Bruce, check out Cr Dowsing's fb page and see how easy it is to capture new councillors. Huge spend-up (years of rate burden) coming our way while raw sewage pours into rivers from source to estuary. Farms and houses. The Minister of the Environment Nick Smith is starting to come round too, so maybe we can expect some government money to flow beyond new toilets for tourists.

Shannon Dowsing - 2 months ago
I would like to clarify that we do not propose high-rate algal ponds or a habitat wetland. The wetland type is a surface flow wetland with a dense read construction. This is known as a polishing wetland and is much more affordable than the processes researched in the wetland trial.
While Bruce is correct that the water coming out of the outfall is 96% free of human DNA that is simply not the only measure to validate the cleanliness. Over a tonne and a half of suspended solids are carried out in the wastewater daily and there is no treatment for pathogens and virus. Both of these need to be addressed in our consent.
Winston, I'm not caught up because I am a new councillor, I believe in the need to do better. DrainWise and the wastewater upgrade are only two of our challenges and will be this council's largest investment. I am conscious of cost, as a member of finance and audit it is one of my roles to monitor financial performance. I would not support an option that is beyond the affordability of the community.

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