Closed landfills pose medium risk to towns

Water contamination, direct surface exposure and gas accumulation identified as risks.

Water contamination, direct surface exposure and gas accumulation identified as risks.

File picture

NINE closed landfills near rural towns have only a medium level of risk of contamination, Gisborne District Council’s environmental planning and regulations committee was told.

The committee was considering a report outlining the preliminary site investigations of small closed landfills at Tikitiki, Tokomaru Bay, Tolaga Bay, Patutahi,Te Araroa, Te Puia, Te Karaka, Whatatutu, and Matawai.

Water and coastal resources team leader Denis Crone said the council had always known there were a lot of these sites.

There were three forms of risk identified: contamination of groundwater and surface water; direct surface exposure (and there were photos in his report of bits of metal and other rubbish poking up); and gas accumulation.

The report asked for authority to do some further investigation for those dumps posing a medium risk.

Acting director for environmental services and protection Lois Easton said the work was part of the investigation into contaminated sites the council is responsible for. The council manages all former landfills as contaminated sites.

“The work involves a preliminary risk evaluation that looks at human health and environmental risks based on available information.”

County and council engineers' records, historical aerial photography, previous site investigations, water quality data and interviews with ex-county and council employees were used to determine high to low-level risks at each site.

“For older landfills like these the risks are mainly environmental.”

The recommendation to the Committee was for further investigation of the 10 landfills, and if required, to develop remediation plans to reduce the potential for direct contact risk and gas accumulation.

Further investigation of the risk to groundwater at Te Araroa, Tolaga, and Patutahi landfills and surface water at Tikitiki and Patutahi landfills were recommended as next steps.

“This additional work may identify the need for resource consents or remedial work such as further capping.”

Application to be submitted in September

An application to Ministry for the Environment contaminated sites fund would be submitted in September.

Ms Easton said the council had already assessed the former landfills in the Waikanae Creek as high risk through this method, and the council had received $84,500 from the Ministry for the Environment’s Contaminated Land Remediation Fund to investigate the levels and sources of contamination.

“This is the first stage in working out what we can do to address the problem,” she said.

“We also have another 18 sites to evaluate and will report back to the committee in the future on these.”

It’s likely that remedial work on at least some of the sites will be required to be included in the next Long Term Plan in addition to remedial work alongside Paokahu landfill.

Acting committee chair Amber Dunn asked what was meant by a statement in the report that the former Waipiro Bay landfill had been disestablished. She was told it had been completely eroded by the sea.

The committee adopted the recommendations.



NINE closed landfills near rural towns have only a medium level of risk of contamination, Gisborne District Council’s environmental planning and regulations committee was told.

The committee was considering a report outlining the preliminary site investigations of small closed landfills at Tikitiki, Tokomaru Bay, Tolaga Bay, Patutahi,Te Araroa, Te Puia, Te Karaka, Whatatutu, and Matawai.

Water and coastal resources team leader Denis Crone said the council had always known there were a lot of these sites.

There were three forms of risk identified: contamination of groundwater and surface water; direct surface exposure (and there were photos in his report of bits of metal and other rubbish poking up); and gas accumulation.

The report asked for authority to do some further investigation for those dumps posing a medium risk.

Acting director for environmental services and protection Lois Easton said the work was part of the investigation into contaminated sites the council is responsible for. The council manages all former landfills as contaminated sites.

“The work involves a preliminary risk evaluation that looks at human health and environmental risks based on available information.”

County and council engineers' records, historical aerial photography, previous site investigations, water quality data and interviews with ex-county and council employees were used to determine high to low-level risks at each site.

“For older landfills like these the risks are mainly environmental.”

The recommendation to the Committee was for further investigation of the 10 landfills, and if required, to develop remediation plans to reduce the potential for direct contact risk and gas accumulation.

Further investigation of the risk to groundwater at Te Araroa, Tolaga, and Patutahi landfills and surface water at Tikitiki and Patutahi landfills were recommended as next steps.

“This additional work may identify the need for resource consents or remedial work such as further capping.”

Application to be submitted in September

An application to Ministry for the Environment contaminated sites fund would be submitted in September.

Ms Easton said the council had already assessed the former landfills in the Waikanae Creek as high risk through this method, and the council had received $84,500 from the Ministry for the Environment’s Contaminated Land Remediation Fund to investigate the levels and sources of contamination.

“This is the first stage in working out what we can do to address the problem,” she said.

“We also have another 18 sites to evaluate and will report back to the committee in the future on these.”

It’s likely that remedial work on at least some of the sites will be required to be included in the next Long Term Plan in addition to remedial work alongside Paokahu landfill.

Acting committee chair Amber Dunn asked what was meant by a statement in the report that the former Waipiro Bay landfill had been disestablished. She was told it had been completely eroded by the sea.

The committee adopted the recommendations.



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