Closed Invercargill landfill poses future risk to environment
Tuesday, 24 December 2019
A closed landfill near the New River Estuary in Invercargill may be at future risk from extreme weather events resulting from climate change, a city council senior staffer warns.
The risks to the environment posed by closed landfills have been highlighted in other parts of the country where they have been disturbed by flooded rivers.
Invercargill City Council works and services manager Cameron McIntosh says the closed Bond St landfill was used for about 70 years until its closure in 2004.
For a long time it was the only solid waste facility in the area and there were no restrictions on what could be dumped at the site.
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The closed site, which has a 60cm cover on top, covers land which was reclaimed and has since been redeveloped, extending from Victoria Avenue to the current Bond St site.
McIntosh says it does not present an immediate risk in relation to extreme weather events, given it is covered.
However, extreme weather events resulting from climate change may present a risk to the closed landfill in future years, given its location on the edge of the estuary.
The effects of sea level rise on the site have not been evaluated and will require further work.
Strengthening work for the stopbanks around the estuary is planned and this may be an opportunity for further work to protect the closed landfill, he says.
The closed Bond St landfill is one of two consented landfills the council administers - the other being the closed landfill at Suir Street, Bluff, with both requiring annual reporting to Environment Southland.
Testing on both continues to show a decreasing trend of contaminant concentrations, McIntosh says.
Other old landfill sites abandoned in previous generations are not always well recorded and are too small to require a consent.
Others are occasionally discovered, including one at Ocean Beach, Bluff, which was uncovered in a storm.
With asbestos identified at the site, Environment Southland is seeking tenders on a project to carry out an investigation and assessment of remedial options.
McIntosh says he welcomes a plan by the Ministry for the Environment to identify former landfills so plans can be made on how to manage them in future.
Southland District Council water and waste manager Ian Evans says he is aware of about 70 closed landfill sites in various locations across the Southland district, some on council sites and others privately owned, but not including farm landfills.
Historically the sites are close to towns and relatively small, he says.
The closed landfills have been covered and capped and in some instances planted with trees or leased out for grazing.
Though no active monitoring is undertaken, staff or contractors visit the sites occasionally.
In order to manage any future issues the district council will retain ownership of the sites and manage risk accordingly, Evans says.
Gore District Council transport manager Peter Standring says there are also historical landfill sites in its district.
Not all records of the sites are reliable, but those known to exist have been capped and either planted with trees, used as playing fields or grazed.
The council does not do ongoing monitoring but staff occasionally visit the sites and the council regularly liaises with Environment Southland on the issue.
Environment Southland senior pollution prevention officer Leonie Grace says the responsibility for monitoring the closed landfill sites lies with the relevant councils where they are located.
Most of the closed landfills Environment Southland is aware of are associated with rural townships.
There are likely to be some private or industrial landfills Environment Southland does not know about, she says.
Transfer stations often operate over closed landfills.