Landfill - background information

30 days of rain accumulation meant the landfill site was already fully saturated when the extreme weather event of 6 April 2017 occurred and caused a leachate overflow. This was the weather event that caused the flooding of Edgecumbe as well as surface flooding and multiple treefalls and slips across the Rotorua District and wider Bay of Plenty.

Some leachate overflowed onto land at the Rotorua landfill, instead of going through the installed wastewater system.

The level of rainfall that occurred was well above the expected design capacity of the landfill’s stormwater management system and led to some stormwater that was partially contaminated with leachate to break through and flow to land. It had the potential to find its way into the Tūreporepo stream, although there is no evidence of adverse effects in the stream.

Capping and sealing of the former open tip face was completed in 2018. Work towards this was already underway at the time of the April 2017 incident.

Bay of Plenty Regional Council (BOPRC) laid six charges against Rotorua Lakes Council (RLC), each carrying a maximum fine of $600,000 – a potential total liability of $3.6million.

The challenge against four charges relating to green waste was of a technical nature and ultimately resulted in two being dismissed by the Court of Appeal and two being withdrawn.

RLC defended the other two charges on the basis of mitigating factors including that the landfill was already in the process of being capped and sealed – which was known to BOPRC – and that the severe weather experienced prior to and on 6 April 2017 was well out of its control and beyond the landfill’s capacity.

On that basis, RLC considered the charges unreasonable and the potential penalties to be a significant cost liability for ratepayers.

Ultimately, the Crown withdrew one remaining charge when RLC agreed to plead guilty to one count to bring the matter to a close.

RLC has to date incurred $480,463 in legal costs and $215,193 in technical engineering advice.

The Council is the owner of the site and the consent holder for the site and remains primarily responsible for consent compliance.

The length of time reflects the legal and technical complexities of the case. The case included a procedural decision that was appealed to the High Court and Court of Appeal, before progressing to the Environment Court for decision.

A restorative justice process was also undertaken prior to the sentencing hearing which occurred over two days in October 2021. (see HERE on RLC’s website)

Environment Judge Jeff Smith reserved his decision at that time and delivered his decision on 19 November 2021.

RLC has made significant investment into the landfill to ensure the protection of the environment, and public health and safety.

The work to cap and seal the historic landfill was completed in 2018.

There was no evidence of adverse environmental effects . However, the incident has been acknowledged by Council and an apology has been extended, without reservation, to mana whenua. Council accepts that it failed to meet its own expectations during the landfill transition and that it let down mana whenua and its neighbours.

The facility has been capped, sealed and grassed.

A leachate monitoring and management plan is in place.

Improvements at the landfill site have included creating new temporary leachate ponds and new bunding.

The site is checked daily for leachate compliance and when rain is forecast. Waste Management checks the ponds carefully to ensure they have sufficient capacity to divert stormwater away from the leachate ponds.

Council will continue to look for improvements wherever possible.

There has been no repeat of what occurred on 6 April 2017, including during the significant rainfall at the end of April 2018 - which resulted in widespread flooding in Rotorua and a state of emergency being declared in the Rotorua suburb of Ngongotaha.

Further work that will happen at the site includes planting of trees covering up to 3 hectares of land adjacent to the capped landfills and removal of vegetation from the old landfill cells.

Council commissioned a report on the landfill in 2015 which made a number of recommendations to address historic issues at the site. The work recommended would itself have posed a risk and would have seen the site still an open face tip. Council determined that the best way to protect the environment and public health and safety was to cap and seal the landfill and that decision was made in 2016.

The same year Council contracted Waste Management to take over the day-to-day management of the site and to progress work to cap and seal the landfill. Work to progress that started in 2016 and capping and sealing was completed in 2018.

The work to cap and seal the landfill was a significant investment, requiring extensive engineering and earthworks.

That work took some months to complete and the weather events of March and April 2017 occurred before the work had been completed.

When waste decomposes (especially organic waste) it produces gas and liquid. Leachate is the liquid produced in the landfill as a result of the breakdown of waste.

At the landfill site, the leachate is captured and directed into the wastewater system and fully treated at the Rotorua wastewater treatment plant.

Rainfall can enter into landfills naturally, which has the potential to flood and overwhelm leachate management systems. For that reason, it is important to manage stormwater so that where possible it is diverted away from leachate, and also to ensure that leachate management systems have enough capacity to not be overwhelmed.

In this case, stormwater entered the landfill. The mixed stormwater and leachate then overwhelmed and broke through the leachate system.