Stop Polluting Manukau Harbour Society says the fight to keep the harbour clean continues. Photo: SUPPLIED
A group tasked with protecting the Manukau Harbour wants Watercare to look at a longer-term solution for supporting the population growth in rural south Auckland.
Stop Polluting the Manukau Harbour Society successfully fought Watercare's plans to build a wastewater treatment plant in Glenbrook, but now have concerns about an interim solution at the rural settlement of Clarks Beach.
Watercare plans to upgrade the Clarks Beach Wastewater Treatment Plant as a short-to-medium option to serve the growing population in Waiuku, Glenbrook Beach, Clarks Beach and Kingseat.
However, Stop Polluting Manukau Harbour Society said Watercare should opt for a longer-term solution instead.
"The Clarks Beach project is an upgrade that is expected to accommodate anticipated growth until 2030," society committee member Margaret Slack said.
"Our focus is on the long term."
The society, made up of local residents, recently won a fight against Watercare to pause a $400 million construction of a new wastewater treatment plant in Glenbrook, to replace three local plants.
Following recommendations from an independent panel of commissioners, Watercare withdrew the notice of requirement to designate land in Glenbrook for wastewater treatment purposes.
The panel found that the site was not adequate, and that Watercare already had the necessary consents to upgrade the nearby wastewater plant at Waiuku on industrial-zoned land next to the Glenbrook steel mill.
Slack said they supported Watercare's original proposal to upgrade Waiuku's wastewater treatment plant, with a plan to build a pipeline to convey the treated wastewater pipeline to the Tasman Sea.
She said in 2016, Watercare undertook a comprehensive analysis to identify the best practicable option for the plant location.
"[That] process identified the pipeline to the Tasman as the preferred option, but Watercare's preference for lower cost and ease of construction led to Watercare 'weighting' these 'requirements' to favour discharge into the Manukau Harbour.
"Our view is that reuse of the treated water and/or a pipe to the Tasman is feasible and will result in sensible economic outcomes."
Watercare said the upgrade of the Clarks Beach wastewater plant would ensure people in rural south Auckland were served, while they reassessed long term solutions.
Watercare chief strategy and planning officer Priyan Perera. Photo: Supplied / Watercare
Chief strategy and planning officer Priyan Perera said the plant currently treated wastewater from about 2500 people in Clarks Beach and Glenbrook.
"Our upgrade will allow it to treat wastewater from up to 6000 people, which is expected to cover growth through to 2030," Perera said.
"We're investing in sophisticated treatment technology - specifically, using a membrane aerated bioreactor - that's proven effective at enhancing the quality of the treated wastewater at smaller-scale rural plants."
While the plant was being upgraded, construction of an outfall pipe to carry treated wastewater from the plant to about 100 metres off the coast in the Waiku Channel would start.
Construction on the outfall was expected to begin later this year, taking about 18 months to complete.
"The treatment plant upgrade and outfall project will lift water quality in the Waiuku Channel, as the wastewater will be treated to a higher standard.
The Watercare site on Glenbrook Beach Road, marked for a wastewater treatment plant. Photo: SUPPLIED
"It will also be discharged on the outgoing tide, where it will be rapidly diluted and dispersed. It's a vast improvement on what's currently in place."
He said protecting and enhancing the Manukau Harbour was a top priority for them.
"We will continue to work closely with the community to find a sustainable, affordable, and appropriate solution that enables the area to grow."
He said both the Glenbrook site and existing Waiuku Wastewater Treatment Plant site would be re-examined, while they reassessed options for a regional southwest wastewater scheme.
The Clarks Beach Wastewater Treatment Plant upgrade and outfall project will cost $60m.
LDR is local body journalism co-funded by RNZ and NZ On Air.