Two wastewater treatment plants in south Auckland will be expanded and upgraded in the next three years, in an effort to accommodate the growing population.
Last month at a community meeting at Glenbrook, Watercare revealed its plans for servicing the Clarks Beach, Waiuku and Glenbrook areas with an option to connect to Kingseat.
In a fresh statement, Watercare head of wastewater planning Andrew Deutschle said a lot of work has gone into a comprehensive assessment of the options over the past 12 months.
“We’re going to be investing more than $500m in a new wastewater servicing scheme for the south-west communities that benefits the Manukau Harbour and enables the area to grow.
“So, it was important to take the time to get it right,” Deutschle said.
Watercare looked at eight options, including three that involved a single wastewater treatment plant that would serve the wider area.
“But this option of upgrading and expanding our existing treatment plants at Clarks Beach and Waiuku takes advantage of the investment we’re already making to upgrade the Clarks Beach Wastewater Treatment Plant.
“[It] better aligns with updated population projections, which are slower than what was previously anticipated, and reflects the feedback we received from the local communities.”
A new conveyance pipeline would carry treated wastewater from the Waiuku plant to Clarks Beach, where it would be discharged via the new outfall that’s currently under construction.
The outfall and discharge were granted consent in 2018 and would serve the area over the long term.
An interim upgrade of the existing Waiuku Wastewater Treatment Plant would also be needed in the short-term to facilitate construction of the main plant, and maintain compliance with current consent standards, while construction took place.
Design work on this was expected to start shortly.
The upgrade of the Clarks Beach Wastewater Treatment Plant was already underway, along with the treated wastewater outfall.
The upgraded treatment plant and outfall would go into service next winter.
Deutschle said permanent storage for treated wastewater would be needed to ensure there was sufficient capacity to hold it until it could be discharged on the outgoing tides.
Once completed, the upgrades to the two treatment plans would lift the combined treatment capacity to serve a population of 20,000 initially.
“But, this level of detail will be ironed out in the design phase.”
Deutschle said their strategy allowed the projects to be conducted in a staged-approach, which spread the cost so, “that we’re not over-investing up front”.
Watercare said the exact timing for the permanent upgrades was dependent on design completion, landowner approvals and the relevant consents.
Design and consenting for the construction work would begin soon.
The construction phase was expected to take about three years.
LDR is local body journalism co-funded by RNZ and NZ On Air.