Rotorua Wastewater Treatment Plant. Photo / Rotorua Lakes Council
Rotorua Wastewater Treatment Plant. Photo / Rotorua Lakes Council
Work has started on a $60 million upgrade of the Rotorua Wastewater Treatment Plant.
The upgrades to the 49-year-old plant are to meet higher projected population demand and to ensure the city’s wastewater is managed in an environmentally sustainable and culturally appropriate way, Rotorua Lakes Council said in a statementtoday.
Rotorua Mayor Tania Tapsell said the upgrade would preserve and protect the region’s lakes for present and future generations which was the vision of the Rotorua Te Arawa Lakes Programme.
“Although our current treatment plant is still among the best in the country and treats recovered water to a very high standard, future-proofing is needed to maintain these high treatment standards and meet projected increased demand,” Tapsell said.
The plant currently processes 19.7 million litres of wastewater daily which includes sewage, industrial wastewater, contaminated groundwater, stormwater and sediment.
The council said the upgrade would enable the plant to treat an average of 25.3 million litres per day with the ability to process 72 million litres during peak inflow periods.
The upgraded treatment process will continue to remove large amounts of nitrogen and phosphorus and disinfect the treated water before discharging it to Whakarewarewa Forest through an irrigation system ahead of entering the lake at Puarenga Bay at Sulphur Point.
3D design of the upgrades to the Rotorua Wastewater Treatment Plant. Photo / Rotorua Lakes Council
Rotorua Lakes Council Infrastructure and Environmental Solutions deputy chief executive, Stavros Michael, said the short to medium-term discharge solution involved upgrading the treatment plant and the continued use of the forest irrigation system for discharge of wai tātari [recovered water] – with operational improvements – while the council and mana whenua worked towards a long-term, new discharge point solution.
“Stage one site works are planned over three years with a comprehensive testing phase undertaken and switching plant processing from old to new seeing the project complete in 2027,” Michael said.
“The upgrade will continue treating wastewater to an extremely high standard, removing pollutants like nitrogen and phosphorus and disinfecting bacteria like E. Coli. The recovered water will continue to meet our water quality targets, sustainability goals and most importantly, future-proofing of our district’s wastewater operations capacity.”
The contract for the work went to open tender and was awarded to Trility in October with site works starting in January 2023.
After the plant’s upgrade, Trility will operate, maintain and renew the wastewater’s networks over the next 10 years.
Trility general manager solutions, Matt Dawson, said they were honoured to build on the mahi tahi (partnership) with Rotorua Lakes Council and be entrusted with the upgrade of the Rotorua Wastewater Treatment Plant.
“We acknowledge the mahi of our partners; Fulton Hogan, Stantec and McKay, who, together with council will work towards a successful project for the Rotorua community.”
Upgrades include:
New inlet screening systems.
Modification of existing ‘Bardenpho’ unit to improve phosphorus and nitrogen removal,
Installation of new membrane reactor units to further clean wastewater and remove nutrients,
Ultraviolet treatment to remove all remaining pathogens and
Addition of wastewater storage capacity to prevent spills from large in-flows that are typically caused by stormwater entering the sewer system.
