14 June 2016
Councillors are to consider a proposal to apply for resource consents to upgrade Rotorua’s wastewater treatment plant and discharge to Lake Rotorua but continue exploring other discharge options.
The Strategy, Policy & Finance Committee will this week (Wednesday 15 June) be asked to recommend to the full Council to proceed with implementation of the preferred alternative to the land treatment system in Whakarewarewa Forest.
Approval is sought to lodge resource consent applications but to continue working with interested parties to investigate alternative discharge options, including the potential for re-use of recovered water (treated wastewater).
Council and CNI Iwi Holdings Ltd agreed to end forest spraying of treated wastewater by December 2019 considered and consulted on a variety of alternatives to come up with preferred options.
The forest system is no longer considered sustainable and a community-led Project Steering Committee was established in 2014 to consider alternatives, headed by an independent chair, with support and advice from experts and independently chaired cultural and technical sub-committees.
The steering committee is agreed on the need to upgrade Rotorua’s wastewater treatment plant but some members have voted against discharging to Puarenga Bay in Lake Rotorua.
Budget approved for the project in Council’s 2015-2025 Long-term Plan (LTP) is $18.6m. The estimated cost of the preferred plant upgrade and discharge to water at Puarenga Bay is $29m which would increase Council’s debt level over the period of the LTP but keep it within the debt cap.
The estimated cost of a plant upgrade and discharge to land away from the treatment plant via rapid infiltration beds is about $54m. This option would increase Council’s debt level by $36m over the LTP period and exceed the debt cap, affect Council’s debt rating and could lead to an increase in the cost of borrowing. This option would also likely increase the wastewater targeted rate by $74 per year per property and as additional time would be required to find a suitable site, it would not be possible to meet the December 2019 deadline.
The preferred discharge option is to discharge the highly treated wastewater to earth contact beds near the wastewater treatment plant in the Sanatorium Reserve. It would flow through the beds and cascade into an existing open channel, then flow overland into Lake Rotorua at Puarenga Bay.
This was considered by most steering committee members to be the preferred discharge option because it would:
Enable council to meet the deadline for being out of the forest;
Provide for the cultural treatment requirements;
Pose no public health risks due to the very low pathogen and virus levels that would be achieved through the upgraded treatment process;
Keep nutrient levels to the same level as the current system (treatment plus forest land treatment) so would pose no environmental risks.
The alternative to discharge at Puarenga Bay would be to pipe the treated wastewater from the plant to a location elsewhere in the catchment and discharge to rapid infiltration beds there. That would require about 20 hectares of land and increase the cost of the project by an estimated $25m.
Initial investigations have found no readily available land for this purpose.
Wastewater treatment in Rotorua
Rotorua currently has one of New Zealand’s best wastewater treatment systems for removal of nitrogen.
The current treatment plant contributes less than 5% of the total nitrogen discharge to Lake Rotorua from all land use within the catchment.
It has been the most successful initiative yet in reducing nitrogen going into Lake Rotorua
Upgrading the plant to a full – rather than partial as is currently the case – membrane bioreactor (MBR) process with additional phosphorous removal and ultraviolet disinfection (UV treatment) would produce recovered water (treated wastewater) of even higher quality.
The full MBR process plus UV treatment would provide double barrier health protection and reduce pathogens to a very low level, safe to return to the environment.
The upgrade would see both nitrogen and phosphorous levels reduced to as low as practicable.
Removal of the forest spray system would improve the quality of the Puarenga Stream catchment.
The upgrade would simplify and streamline the treatment process and the technology proposed is well proven.
Also on the agenda …
A new waste bylaw is proposed to support Rotorua Lakes Council’s new waste management direction which aims to increase recycling and reduce the amount of waste going to landfill.
The bylaw would replace Council’s existing Waste Collections and Sanitary Landfill bylaws (both 2012) and is part of a review of waste and recycling services which Council started in August 2014 and consulted on as part of the 2015-2025 Long-term Plan last May.
Policy for earthquake prone council buildings
Councillors will be asked to recommend Council adopt a proposed framework for decision-making regarding the level and timing of earthquake strengthening works on Council owned or leased buildings.
The framework will assist with assessment of buildings and improving any deemed earthquake prone.
The Strategy, Policy and Finance Committee will consider a recommendation that it recommend to Council to adopt the Annual Plan 2016/17.
If the recommendation is approved, it will go to the full Council at its next meeting, on 23 June 2016, for adoption and for Council to strike the rates for the new financial year.