One of 26 Hungarian-built Ganz Mavag trains which are being scrapped and buried at Wellington's Southern Landfill.

Fifty old Wellington commuter train carriages contaminated with asbestos are being buried at the city's dump because it is the cheapest disposal option.

The move to scrap the Ganz Mavag trains comes after a deal struck to sell the carriages to a South African buyer fell through last year.

Six of the units sitting at railway sidings north of Upper Hutt Station were moved earlier this year after attracting trespassers, vandalism and graffiti.

KEVIN STENT/STUFF One of fifty old Wellington commuter train carriages with asbestos in its walls makes its way up Taranaki Street on its way to the city dump for burial.

On Tuesday, contractors began transporting the carriages by truck to Wellington's Southern Landfill where they will be scrapped.

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Metlink rail operations manager Angus Gabara said the bogies, motors and other recoverable scrap would be separated from the units, but there was asbestos in anti-drum coatings inside the walls of the trains.

GWRC/SUPPLIED One of the 50 old Wellington commuter train carriages arrives at its final station - the Southern Landfill.

Each carriage is about 20 metres long and weighs about 25 tonnes.

"The cost of removing the coatings to salvage the scrap is too expensive. Asbestos is contained in the anti-drum coating and will remain undisturbed during the dismantling and transport to the Southern Landfill," Gabara said.

The carriages will then be crushed and buried. "Burying the carriages is the least expensive and safest way to dispose of the carriages because of the asbestos issue."

GWRC/SUPPLIED Contractors began delivering the Ganz Mavag carriages to the dump on Tuesday.

Wellington City Council (WCC) infrastructure and sustainability portfolio leader Iona Pannett voiced concerns about putting the "enormous amount" of scrap in the ground, especially given the council was trying to stop the dump's expansion.

"I'm not very happy about 50 trains going in to our landfill and we have to be very careful about the asbestos," Pannett said.

Council spokesman Richard MacLean said excavators with 'demolition jaws' were making quick work of the carriages.

MAARTEN HOLL/STUFF Wellington's old Ganz Mavag trains have been little more than a canvas for graffiti artists of late.

"The cut-up materials are being buried in a specially-designed and isolated part of the landfill that is set aside for the disposal of asbestos."

MacLean said there would be no problems with leaching because not much rainwater could get in under the landfill cap.

Gabara said Metlink had been trying to sell the old carriages for reuse for years. Initially they were sold to a South African buyer, who took a first lot of 16 units (32 cars) to be reused in service in Africa.

ROSS GIBLIN/STUFF The last of Wellington's Ganz Mavag trains made its final trip between Wellington and Melling in May 2016.

But the deal for the remaining 26 units officially fell through in late 2017.

Greater Wellington Regional Council spokesman Stephen Heath said the South African firm knew the carriages contained asbestos, but believed the deal failed because it could not cover the "substantial shipping costs".

The operation is expected to take a month, while one carriage has been gifted to Christchurch's National Railway Museum.

SUPPLIED Some Ganz Mavag trains were shipped off to South Africa in 2014.

The Ganz Mavags carried more than 67 million passengers during their time in the Wellington region.

TIME PASSAGES

1979 to 1982: 44 two-car Ganz Mavag units are built in Budapest, Hungary.

June 1982: The first Ganz Mavag runs in on Wellington's commuter train lines.

March 1983: All Ganz Mavag units are in service, but they never run on the Johnsonville line because they do not fit the rails and cannot brake hard enough.

May 27 2006: the last Ganz Mavag trains runs on the 2.17pm return service to Melling.

2013: 42 units are sold to a South African buyer (16 are shipped across in 2014).