It is unlikely that wastewater engineers have job descriptions requiring media stand-ups, but in March infrastructure operations manager Simon Mason stepped up for his employer Queenstown Lakes District Council (QLDC) to explain the failure of its wastewater disposal field next to the Shotover River.
The field was meant to drain already-treated wastewater through gravel before entering the river. Instead, there had been pooling, spilling, visiting wildfowl - risking a plane crash from bird strike at the next-door airport - and abatement and infringement notices.
Mr Mason said there had been "no easy answer". Emergency action was necessary and, with no consent from the Otago Regional Council (ORC), the treated wastewater would now go straight into the river.
Four months on, he says he hopes, by October, to present advice about five short-listed alternate disposal options to a project steering group, then to councillors, leading to a resource consent application by next May.
Inevitably, there has been a barrage of media interest in a saga that features both sewage and the seemingly-pristine Shotover, which flows into Queenstown’s Kawarau River and the tourist draw-card Lake Wakatipu.
Stories featured Mr Mason saying, at the stand-up, that he would let his children swim in the Kawarau. One story claimed that a movie shoot had been abandoned over contaminant fears.
A key criticism from the community has been the length of time it took to close the field with no alternate solution ready. It has been five years since problems started.
A decision to consent the temporary change, or not, will be determined by the Environment Court, and an alternative disposal system will be implemented, but a bigger issue faces QLDC. Its wastewater infrastructure, not just at Shotover, is playing catch-up with a soaring population, projected to rise further, from 54,000 residents to perhaps 69,000 in the next ten years.
QLDC wastewater budgets have grown and changes are planned but more are pending about treatment plant locations, capacity, type and disposal methods.
To compound matters, there is the problem, not unique to Queenstown, that some wastewater goes to private systems outside the local council’s jurisdiction, plus any badly-managed farmland can release pollutants. It can be hard to prove culprits for water quality deterioration as waters mix.
Meanwhile, Mr Mason says he wishes people would also spare a thought for his team’s welfare, in the face of a media storm. It’s not glamorous work and they have suffered "the heat of fierce scrutiny and, at times, what could best be described as vitriol".
Managing large amounts of wastewater to protect people and the environment means firstly managing its treatment and secondly its disposal.
Earth Sciences New Zealand (formerly Niwa) says most treated wastewater from New Zealand’s 320 municipal wastewater treatment plants is discharged into either rivers, streams or on to land and QLDC is quick to point out that its disposal practices, and efforts to improve them, are typical.
It operates the Shotover plant in Queenstown plus three more at Wanaka, Cardrona and Hawea. Solid waste, separated from liquid through the treatment processes, is nearly all trucked to a Winton landfill. It’s not ideal - a 300km round trip with emissions and risk - and happens six days a week.
QLDC says it is reconsidering the drudge of its sludge-carting and whether an alternative could be "accelerated".
The remaining treated wastewater is disposed locally but the Shotover plant is the only one discharging to water. The other plants drain to land. Iwi object to discharges straight to water.
Like a toilet U-bend, the Shotover wastewater plant is out of sight unless sought out. It is tucked away next to Route 6, parallel to the Shotover’s delta adjoining the Kawarau River and just before the bridge to the suburb Shotover Country.
Prior to 2017, all wastewater arriving here from various suburbs went through an oxidation pond system - a basic treatment plant - and was then released into the Shotover River.
In 2017 a system called a Modified Ludzack-Ettinger (MLE) opened at the plant, alongside the ponds. MLEs use more infrastructure and energy to aerate wastewater in a way that enables micro-organisms to thrive and break down pollutants better, including dangerous pathogens and nutrients including nitrogen and phosphorous that can cause algal blooms and destroy river health.
Two-thirds of the wastewater was treated through the MLE and a third treated in the ponds, then the waters were mixed together - and still released into the river.
In 2019, the fated disposal field was added to the process’ tail end, after years of deliberations about changing the disposal method.
The treated wastewater was meant, additionally, to drain through buried crates and a shallow layer of gravel before entering the river but problems were identified from 2020. The field increasingly pooled and overspilled, causing the council to be slapped with enforcement notices by ORC.
The council stresses that treated water that did pass through the field was only marginally more pure. The field was not providing much "polishing" - an eyebrow-raising technical term for cleaning wastewater more after initial treatment.
Four years of investigations and efforts to make the field effective then failed. The field, and a mitigation plan to net it from birds, were both abandoned this March and the plant reverted to releasing its treated water directly into the Shotover, without ORC consent.
QLDC stresses that the plant has always discharged treated wastewater into the river and the percentage of wastewater that goes through the MLE plant has risen from two-thirds to 80% and could rise further as the MLE expands, improving the discharge’s quality.
Mr Mason says a "positive" relationship has been maintained with ORC. "They have been pragmatic with us."
However, campaigners stress that four years is a long time to know about a problem, not communicate fully about it nor agree a fix.
Queenstown Lakes Community Action spokeswoman Nikki Macfarlane says historical information she sought from council about its deliberations on the issue had indicated technical problems but not operational failure.
"There should be a process of reflection to avoid this kind of thing again. The public must have information, in a timely way, to understand problems and properly assess what is being proposed, particularly costs that could increase rates."
The council is clear about its proposed disposal options for the Shotover plant; three would dispose to land and two to water. The council’s budget for the project is $77.6m, but some options could exceed it.
The land options are all around the airport, majority-owned by QLDC. The treated water could be: dispersed within shallow trenches spread over 90ha; injected into shallow soakaway wells dotted across the area; or injected into deeper wells, using 30cm-wide bores, to join the groundwater 40m below.
The shallow or deep wells could cost around $75m but the trenches could cost up to $200m.
The cheapest water option, at up to $35m, would dig a channel from the treatment plant to the Kawarau River where there is a greater volume of water than in the Shotover. Dilution can be part of the solution and it would likely meet the proposed new national wastewater performance standards - that have been criticised by environmental campaigners for being low.
The other option is to construct a wetland, along the same route, out of sand or gravel. Plants would be selected to discourage birds and allow "polishing" to occur as the water travelled through the wetland to the river. It could cost up to $60m.
The rising tide of the region’s population, and the need for capacity to treat wastewater and manage its disposal safely for people and the planet, must be a thumping headache for decision-makers.
The council’s spatial plan strategises the importance of denser housing but development is already spreading like fingers into rural areas between the region’s mountain ranges and lakes, with plots snapped up by people wanting new-builds and a better life, while also, ironically, edging a sprawling Queenstown towards city status.
There must be more treatment plants and disposal methods, or longer pipes to bigger treatment plants with greater disposal capacity, or both, and levels of contaminants released to the environment must be constrained in the face of more wastewater.
Consequently, the Shotover plant’s MLE is expanding and Wanaka’s wastewater infrastructure is also being upgraded due to capacity issues.
The treatment plant for Hāwea, the rural settlement to the north of Wanaka, has reached capacity and is closing by around 2029. Wastewater will be piped to the Wanaka treatment plant.
QLDC is, conversely, designing a new wastewater treatment plant for the rural settlement at Kingston at the southern tip of Lake Wakatipu with the intent to serve a housing development called the Kingston Village and have capacity for the Kingston township.
A particular problem area, that QLDC calls the Te Tapuae Southern Corridor, is land south of the Kawarau River, on the eastern shores of Lake Wakatipu.
Farmland here, and in other places in the wider region, is being bought by financiers and developers for conversion to housing estates. They have attractive, rural names such as Hanley’s Farm but the reality is a sea of large black roofs rather than green paddocks and, under them, thousands of toilets.
Southern Corridor wastewater managed by QLDC is being piped to the Shotover treatment plant but there are issues. Piping is not cheap and local disposal not an option, the council says.
It is developing a "structure plan" to help guide growth in the area and consultation documents warn that "wastewater disposal to land is not suitable ... due to ground conditions".
Jack’s Point - a high-end estate in the corridor - is limiting development on its own 560ha to 840 residential lots and a golf course, operating its own wastewater treatment plant and disposing to dripper fields on farmland.
The estate’s resident association spokesman Clive Geddes says the objective is a "low footprint on the natural environment."
However, another estate is planned in adjacent paddocks. Consent for Homestead Bay - a whopping 2800 homes - is going through the fast-track consent process. Its application is vague about options for wastewater treatment and disposal, including possible use of QLDC’s system or a private system.
Ultimately, any treatment and disposal system, whether run by the state or privately, ends up in a shared environment and needs regulating. The more wastewater, the more regulatory responsibility to protect.
Mr Mason hits the nail on the head regarding the area’s issues from a financial perspective too, as incomers plan their dream homes and tourism continues: "Ensuring growth pays for growth will be paramount to keeping the cost of infrastructure provision affordable."
