Historic landfill sites across Nelson Tasman at risk of sea level rise

Sunday, 7 July 2019

The Atawhai closed landfill site covers 49.6 hectares across parts of The Wood, Founders Park, Miyazu Gardens and Neale Park. The Boulder Bank and state highway offer some protection from sea surge and climate change.

Almost 20 historic landfill sites in the Tasman district are at risk of being exposed by storm surges and sea level rise.

Information from local councils show there are 20 closed landfills across Nelson and Tasman, 18 of which are located on the coastline or near rivers and estuaries.

A Local Government New Zealand (LGNZ) report on council infrastructure exposed to sea level rise found five of the closed landfills would be exposed by a 0.5-metre sea level rise and 18 would be exposed by a 1-metre sea level rise.

The report showed predictions for the rate of sea level rise varied considerably, with NASA scientists predicting between a 30 centimetre and 1.3 metre increase by 2100 and NIWA between 40 centimetres and roughly 1 metre.

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The Fox Glacier Township Landfill in South Westland was torn open when the Fox River breached its banks during a huge rainstorm in late March, which forced the swollen river through about 40 metres of bush, causing the land under the old site to erode.

Tasman District Council community relations manager Chris Choat said there were 19 closed landfills within the Tasman District and eight of those were on the coast.

They included the Richmond Resource Recovery Centre, Robinson Rd in Mariri, Aporo Rd in Tasman, Kina Beach Rd, Old Wharf Rd in Motueka, Lodder Lane in Riwaka, Pah Point near Kaiteriteri and Rototai in Takaka.

Volunteers on the West Coast continue to clean up rubbish from an old landfill in the Fox River.

A further nine closed landfill sites were located on river flats and near estuaries, including Appleby, Cobb Valley, Murchison, Ngatimoti, Kaiteriteri, Tasman Highway, Tapawera, St Arnaud and Waiwhero.

Choat said a management plan for the closed landfill sites required visual inspections be undertaken every two years to identify damage to the landfill cap, subsidence or erosion along with other issues.

While the plan covered monitoring for groundwater, surface water, leachate and landfill gas, it did not explicitly account for climate change or sea level rise.

But Choat said since the plan was completed in 2011, environmental risks had been recognised and further steps had been taken at some of the sites to preserve their integrity.

The former landfill site at the Richmond Resource Recovery Centre had coastal protection for the last 30 years and additional rock was placed in early 2017 to repair and improve existing rock protection around the centre and the Great Taste Trail, which runs around the perimeter.

Volunteers, DOC and council staff face a huge job cleaning up beaches strewn with rubbish from an old dump near Fox Glacier township.

The site had suffered from erosion of rock and gravel before 2017, but the council had no knowledge of waste material being exposed.

At the Rototai closed landfill site in Takaka, rock protection was installed at the southern end in 2000, with additional rock work in the northern end completed last month to reduce the risk of erosion.

'We have not identified any loss of waste material from this site in the last 15 years, but the edge of the site was not well protected and the new rock work is to reduce the risk of erosion in a large flood event.'

Choat said further risk of erosion and inundation at some of the closed landfill sites would be reassessed this year, along with an increase in maintenance and inspections.

Any capital works would be considered during the development of the Long Term Plan 2021-2032.

Clay has been used to cap the old Tasman Kina landfill site.

The only active landfill in the region, the York Valley landfill in Nelson, was jointly managed by the Nelson and Tasman councils. It was more than 3 kilometres from the coastline and was not at risk of a 3-metre sea level rise.

In Nelson, the only closed landfill was the Atawhai closed landfill which was first opened in 1942 and closed in 1987 and covered approximately 49.6 hectares bordering Queen Elizabeth II Drive.

Nelson City Council infrastructure group manager Alec Louverdis said the scenario Westland District Council faced with the Fox Glacier historic landfill was very different to the situation at Atawhai, which wasn't at risk of being washed out by a river in flood.

While it was close to the ocean, it was protected from storm surge firstly by the Boulder Bank and then the state highway.

'We've had serious floods in the region and that whole closed landfill has experienced no issues.

'Even in Cyclones Gita and Fehi, there were no implications to the Atawhai landfill, in fact none of those areas were exposed.'

He said the council was investigating how susceptible the landfill was to climate change and sea level rise.

'It's an ongoing piece of work, not just for us but for everyone in New Zealand and everyone around the world.'

Following the erosion of the landfill at Fox River, Forest & Bird conservation ambassador Dr Gerry McSweeney said a national discussion was needed to address the issue of historic landfills.

'It is a question of getting the Ministry for the Environment, who should have a register of all of these, and district councils and regional councils to be going through all this really thoroughly and working out which ones will be exposed to hazards and what we have to do before the events such as happened at Fox Glacier happen again.'