Please see correction at the end of this article.
Rotorua Lakes Council has pleaded guilty to discharging a dangerous substance - with levels of bacteria equivalent to raw sewage - from the city's dump site and, in a diluted state, it may have later flowed into popular Rotorua waterways.
The council was warned repeatedly over eight years and was eventually charged by the Bay of Plenty Regional Council in 2017.
After a four-year court battle, the district council pleaded guilty and faces a maximum fine of $600,000.
Puarenga Stream, where penny divers swim for coins from tourists, was one of the waterways. It is described as having significant cultural values and also flows through the world-famous tourist attraction, Te Puia.
Details of the case can be revealed after the district council pleaded guilty in the Rotorua District Court in May to a charge under the Resource Management Act of discharging a contaminant, namely stormwater contaminated with leachate, on to or into land in circumstances where it may enter water.
Details were suppressed but that was lifted when the guilty plea was entered.
The leachate is described in court documents as having a faecal rate equivalent to raw sewage.
Contact with contaminated water can cause serious illnesses such as gastroenteritis, respiratory problems, skin rashes and other serious illnesses and cause serious environmental effects such as destroying fish life, the summary of facts said.
The summary outlines the environmental impacts on Tureporepo, Waihuahuakakahi and Puarenga Streams.
In 1998, the council was convicted of three similar offences and fined $24,000.
Under the district council's resource consent, it must ensure landfill leachate does not enter the stormwater treatment system and that the stormwater system is adequately maintained.
During inspections in November 1999, August 2006, August 2007 and May 2008, regional council officers found leachate discharging from the landfill face entering a stormwater pond that discharges into the Tureporepo Stream, the summary said.
In 2008, the regional council issued an abatement notice but it was later cancelled at the request of the district council.
The council tried different measures to improve the situation, including installing vertical pipes to improve drainage and constructing a leachate pond.
However, in November 2009, May 2010 and January 2011 the regional council found leachate had again broken through the landfill site and flowed into a stormwater pond that discharged into the Tureporepo Stream.
In August 2011 and again in May 2013, the regional council told the district council it needed plans to manage stormwater at the landfill site given increasing rainfall. The district council was also told to upgrade the leachate pump and reticulation system.
In August 2014, the council notified the regional council there had been a discharge of leachate from the landfill site to land where it entered water.
The summary said the discharge had been caused by high rainfall and a pipe that was too small.
The district council had earlier said it was going to upgrade the pipe but that had not happened, the summary said.
In February 2015, the regional council told the district council to stop discharging landfill leachate to land where it might enter the Tureporepo Stream. It issued an abatement notice and included a final prosecution warning.
The letter requested a report by March 2015 outlining what steps the district council would take to ensure no further discharges.
In response, the district council engaged Tonkin & Taylor to conduct a review of the risks at the landfill, which made several recommendations. However, none of those recommendations were implemented and the council instead went on to contract a waste management specialist company to manage the site.
The regional council met with the site operator in July 2016 to make them aware it was at the "end of its patience" and any further discharges would result in prosecution.
Shortly after taking over management, the site operator noticed leachate was breaking through and heading towards Tureporepo Stream.
The site operator engaged Tonkin & Taylor to find a solution and recommendations were made in November 2016.
On April 6, 2017, a regional council officer carried out an inspection of the landfill site and found leachate was illegally discharging in varying places, and in one area "at a high rate" into an open stormwater drain.
At the time of the inspection, site management staff and contractors were trying to address leachate discharge by pumping leachate from there to a point on the side of the landfill where it could flow to a leachate pond.
However, that pond was overflowing from two points and flowing into another pond which was in turn overflowing and discharging to a stormwater system. That system was then flowing into the Tureporepo Stream.
The officers also noticed a sudden increase in the volume of water flowing along the stormwater drain and into the stormwater pond. They walked upstream and found it was leachate that had broken out which had previously been contained by a bund. The bund had collapsed that afternoon.
The summary stated that a sample taken from the April 6, 2017, discharge of leachate onto land had elevated conductivity, chloride, ammoniacal-nitrogen and an extremely high faecal coliform concentration, namely 21,000,000 cfu/100ml.
The high faecal coliform result is equivalent to the concentration found in raw sewage. While it is likely the leachate was diluted as it passed through stormwater pond B and after mixing in the receiving stream, there remains the concern that this concentrated toxicant source could have had an adverse impact on the Tureporepo Stream, the summary said.
When regional council officers asked the site operator's staff what their understanding of the leachate system was, they said they had been shown it when they started work at the site in July 2016 but were not contracted to operate it and did not have a good understanding of it.
Site staff said there was no handover between the district council's previous landfill manager and the site operator. Instead, two other staff from the district council explained how the leachate system worked. There were also no formal instructions about how the valves for the leachate system worked.
The summary said the impact of high faecal contamination on the Puarenga catchment was "of concern to human health".
The landfill is now closed as an active landfill and refuse taken there now goes to a transfer station and is transported off site.
Since April 6, 2017, the district council and the site operator have made a number of
improvements to the way they manage stormwater at the landfill, the summary said.
The Rotorua Daily Post asked the district council a series of questions relating to the case, including why it took just under four years to plead guilty, why it didn't fix the problem despite being warned by the regional council several times over a period of eight years and whether it had warned anyone impacted by the discharging of leachate that it could be dangerous?
The council was also asked why none of the recommendations in the Tonkin & Taylor report were implemented and if any staff had faced disciplinary action.
In a written statement via the council's communications team, council chief executive officer Geoff Williams said it couldn't provide more comment until sentencing on October 11.
Williams said the regional council brought six charges against the district council in 2017 alleging various breaches in March and April 2017.
He said the charges followed the heaviest period of rainfall on record in the Whakarewarewa catchment area in the 30 days prior.
Four charges were subsequently dismissed and a fifth was dismissed when the district council pleaded guilty to the sixth charge.
What is leachate?
Leachate is the liquid that drains or 'leaches' from a landfill.
Leachate can have elevated concentrations of contaminants, such as ammoniacal-nitrogen, heavy metals, pathogens, and organic compounds.
How the system is meant to work
All stormwater discharged from an area of the landfill site is intended to be captured and
directed to a stormwater pond, where it is treated for suspended solids and then discharged into the Tureporepo Stream.
The stormwater captured at the landfill site and discharged into the surrounding tributary streams is to be free of leachate.
All leachate is to be captured by the landfill site's underlying leachate liner and reticulation system and then pumped into district council's wastewater pipeline system.
Correction & Clarification
An earlier version of this article published on Thursday 2 September 2021, stated that Rotorua Lakes Council admitted it discharged a dangerous substance – with levels of bacteria equivalent to raw sewage – from the city's dump which later flowed into popular Rotorua waterways.
For clarity, Rotorua Lakes Council pleaded guilty to discharging stormwater contaminated with leachate onto land in circumstances it may enter water. While the leachate was tested and had levels of bacteria equivalent to raw sewage, that testing was at a point before it entered the stormwater pond within the landfill itself. The discharge followed prolonged and abnormal rainfall. Stormwater contaminated with this leachate did enter the Tureporepo Stream, albeit in diluted form. While leachate poses potential harmful environmental effects on surrounding waterways, the Summary of Facts did not explicitly state that there had been adverse environmental effects from this discharge in any waterways.
The article also stated that "the substance flowed into Tureporepo and Waihuahuakakahi streams and into Puarenga stream". The Summary of Facts did not state leachate had entered the Waihuahuakakahi or Puarenga streams as a result of the April2017 event, but that leachate entered the Tureporepo Stream. The Summary of Facts did make reference to both the Tureporepo and Waihuahuakakahi Streams being located in the western and southern areas of the Puarenga Stream catchment, and the environmental effects of leachate in these waterways was also set out in some detail.