Every aspect of our operations is dependent on and impacts the natural environment so we have a responsibility to protect and enhance it.
In the past year, we have made significant strides in creating value within our natural environment and moving forward in our resource recovery journey.
We began the first year of our vegetation project in the Hūnua Ranges, planting more than 86,500 native trees and shrubs in the catchment surrounding some of our most important water sources. This came about with the purchase of forestry rights to a 1,900-hectare commercial pine forest in the ranges. We have worked with Auckland Council to amend that forestry right so that commercial forestry operations will end decades earlier than they otherwise would have. This means no more pines will be planted on the land, and the site will be progressively regenerated with native trees and plants over the next 30 years.
By regenerating the land with native trees, we will significantly reduce the slips in our catchment area. This will protect the water quality of the supply lakes and, ultimately, Auckland’s water sources for decades to come.
In the same vein of protecting our water sources, we commissioned a new water treatment plant for Warkworth, with water supplied from a secure underground aquifer, instead of the at-risk Mahurangi River.
The new plant is a substantial investment and will double capacity and cater for growth in this fast-growing region. The supply is more sustainable as the bore provides a guaranteed supply, unlike the river, which ran low in previous years.
On the wastewater side, we commissioned the first set of ‘containerised plants’ to service local communities in Warkworth, Owhanake and Clarks Beach while the existing facilities are going through significant upgrades, due to be completed in a few years’ time. The containerised plants use the sophisticated membrane bioreactor technology (MBR) to treat wastewater and are a sustainable solution since they can be disconnected and moved to another location when we are finished.
Using resources effectively and reducing our environmental footprint is a continued focus for us and innovation plays a key role in realising this objective. We undertook several technology trials at our Māngere Wastewater Treatment Plant. These included a mini reactor growing anammox bacteria that can be used in our biological treatment process to reduce the use of oxygen and carbon, and short cutting nitrogen removal in the aeration process and thereby reducing the energy required. We achieved the targets we set for phase 1 of our energy efficiency and neutrality programme – saving 8GWh of energy through various process improvements across our treatment processes.
We are on a similar journey at our Rosedale Wastewater Treatment Plant where we are building a thermal hydrolysis facility that will be completed in 2022. This will allow us to sterilise the biosolids from the treatment process and create fertiliser that can be used for beneficial purposes.
We installed our first solar array at the Pukekohe Wastewater Treatment Plant. The 122kW ground-mounted array consists of 400 solar panels and is the first renewable energy project of its kind to be completed by Watercare. The panels help power a pump station, which sends wastewater piped from surrounding districts to the treatment plant, located approximately one kilometre away. The panels can generate about 170 megawatt hours of electricity per year, saving up to $20,000 annually.
Two further solar facilities have been installed at Wellsford Wastewater Treatment Plant and Redoubt Road Reservoir, Manukau. The Redoubt Road Reservoir will also feature a Tesla battery pack, so that the solar energy generated can be stored for use at night-time, and is expected to see a 75% reduction in grid use.
Weather patterns are a big variable in the consistent delivery of our services. A change in the load on our digesters at Māngere Wastewater Treatment Plant in the summer months caused an odour issue in the surrounding areas. Our team investigated and implemented controls to address the issue and we kept our customers and the community informed of the situation. We plan to add diagnostic meters to our digesters to alert us to load changes in the future.
We are also encouraging Aucklanders to use water wisely this year in case the dry weather that is affecting much of New Zealand continues.
The Hūnua and Waitākere ranges – where Watercare has nine water storage dams – received 34% and 44% less rainfall than normal respectively for the January to June period. As a consequence, the city’s total water storage was 59.2% at the end of June 2019, which was 25% less than normal for that time of year.
The prolonged dry weather is also having an impact on demand. Some of Auckland’s fringe suburbs as well as rural areas to the north have houses with rain tanks rather than municipal supply. These residents rely on water tanker operators to fill their tanks when they run dry and as a result, demand from water tanker filling stations has risen sharply.
We are closely monitoring the dry weather situation and we are carefully balancing our water sources by maximising production from our river and aquifer sources to reduce demand on our dams. We are considering the best options for meeting future demand as well as the best timing for any additional water sources.
Our aim is to achieve energy neutrality at our Rosedale and Māngere wastewater treatment plants, which are large energy users, by the end of 2025. This is a part of our large-scale climate change mitigation programme and will enable our operations at these plants to be self-sufficient.
Phase 1 of our energy programme was to achieve 8GWh of energy savings across Watercare by the end of 2018. We did this successfully by bringing together our people and their knowledge: a cross-functional team of process specialists, onsite engineers and the teams on the ground who believed in our mission, utilised their varied expertise and skills sets, identified opportunities and reported on progress.
Our approach was to optimise our processes to use less energy by improving the control strategies and replacing end-of-life equipment with more energy efficient alternatives. We also installed solar and battery technology at three sites and identified opportunities at treatment plants and pumping stations that consumed the most energy and were most likely to realise large cost and energy savings.