Wellsford wetland trial

The design involves the construction of two new wetland systems

Watercare resource consent planner Ban Najim Aldin at the oxidation pond in Wellsford.


Watercare has been granted a resource consent to trial a wetlands wastewater system in Wellsford.

The current wastewater plant, which is on a tributary of the Hoteo River, on State Highway 1, just south of the Wellsford Golf Club, has been operating without consent since 1999. It is the last non-complying wastewater plant in Auckland.

The two-year trial will involve the creation of two 40m x 40m ponds, which will help process waste from 1800 properties in Wellsford and Te Hana.

The ponds will have a rock base that will help remove nitrogen from the water and eventually a UV system to remove pathogens.

Watercare resource consent planner Ban Najim Aldin is confident the new wetlands will improve the quality of the effluent to the Hoteo.

“The new ponds will also be covered to prevent bird waste from contaminating the processed water and will be elevated to address concerns that the current ponds, which are low-lying, are susceptible to flood waters,” Najim Aldin says.

Rock base isn’t normally used in wetlands in New Zealand because of the expense of importing it. However, Watercare has found sources of the material in both New Zealand and Australia. Najim says if the system proves successful, Watercare will look at implementing it at other plants.

“The current wetlands are making effluent quality worse and will be decommissioned. During the trial, water that goes through the new wetlands will be tested before it goes back through the plant to ensure it is safe to discharge.”

Watercare looked at a number of options prior to choosing the trial, including the construction of an entirely new plant, but dismissed that option on the basis of cost.

The Wellsford plant operates under temporary conditions, but this will become invalid in five years.

“We need to make a decision on a final system before that deadline and to cater for a growing population.”

Rodney Local Board member Colin Smith is angry that Watercare has chosen to do that trial rather than invest in a full overhaul of Wellsford’s infrastructure.

Mr Smith says consultation on the idea was poor and the result is a feeble attempt to provide for Wellsford.

“Watercare consulted with Wellsford once six years ago and then we saw the same plan again last year that had previously been rejected,” Mr Smith says.

“There is waste coming up into people’s bath tubs here because the infrastructure built in the 1960s is stretched and they want to put in a new wetlands system. How stupid is that?”

Mr Smith says problems occur when large amounts of stormwater and wastewater meet in the network.

However, Watercare infrastructure and environmental planning manager Mark Bourne says Wellsford infrastructure is adequate for the current population.

“It is illegal to have wastewater and stormwater connected by the same pipe so any overflow for this reason is due to illegal plumbing or cracks in the pipes,” Mr Bourne says.

“We do regular checks of our assets but if anyone comes across an issue before we do, they should contact us immediately.”

Mr Bourne says that if growth forecasts for Wellsford are accurate, then its main systems will need to be upgraded.

“All new subdivisions will have their own pipes installed, but areas where it meets the main system may need upgrading to increase capacity.

“We haven’t set out any timeframes for this upgrade, but we will assess this and make sure required works happen ahead of the growth. The wetlands are a separate issue aimed at improving the environment, as well as catering for growth.”

Watercare will set-up a liaison group early next year and the wetlands trial is due to start in the second half of the year.


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