Longer use of the dumpster is cheaper than taking the garbage elsewhere

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Extending the life of Dunedin’s Green Island landfill would be at least 33% cheaper than trucking waste to an out-of-borough landfill, according to an economic assessment by Dunedin City Council.

The council has applied to extend permits for the Green Island landfill for up to seven years before the new Smoot Hill landfill opens in 2028-29.

In October, the valid approvals for the “Green Island” landfill expire.

An economic assessment included in the Green Island expansion application, carried out by consultants GHD, outlined a “strong case” for continued use of the Green Island landfill.

“Additional landfill capacity is needed,” GHD’s assessment states.

“The most cost-effective solution that minimizes emissions, road wear, congestion, job losses and specific environmental impacts in Dunedin is to allow resource use to continue operating the Green Island site beyond October 2023 and for the void to be expanded.

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“This will provide sufficient capacity to accommodate delays in commissioning the Smooth Hill site.”

According to the assessment, Council has already looked into truck waste from Dunedin.

The nearest regional landfill, the AB Lime site in Vinton, requires a trip of approximately 400 km from Green Island.

Off-site disposal can cost upwards of $150 per ton, but would need to be around $100 per ton to be financially competitive with the long-term solution of a landfill at Smoot Hill.

The Green Island Landfill site would “by far compare best” in terms of costs to the Smoot Hill site due to the significantly lower permit extension cost for the Green Island Landfill compared to construction costs for the Smoot Hill site.

“Given that the Green Island site is more cost-effective than the Smooth Hill site, it is likely to be at least 33% more cost-effective than the out-of-district option,” it said.

In addition, there were other costs associated with off-site disposal compared to local disposal.

There would be more carbon emissions, it is said.

One truck that transports waste to AB Lime 100 times a year emits about 75 tons of carbon a year.

Given that 35,000 tonnes of municipal waste needs to be disposed of each year, this would likely mean that 1,000 trucks carrying 35 tonnes each would make the journey each year, creating around 750 tonnes of carbon emissions per year.

In addition, the trucks will impose significantly higher costs on the road network in terms of wear and tear, the assessment said.

1,000 trucks will also create traffic jams on the route.

In addition, the closure of the Dunedin landfill in favor of the Southland landfill would result in the loss of seven or eight jobs in the city, the assessment said.

A further environmental impact assessment, carried out by consultants Boffa Miskell, says the council has also previously considered creating a waste-to-energy facility for the city.

“However, this was not preferred because of the high capital costs, the need to secure large sources of combustible waste, the incineration of waste that is not acceptable to mana whenua and the ongoing need to dispose of ash (20%) from waste inputs to landfill.”

The Otago Regional Council has approved an application to expand the Green Island Landfill, but it has been put on hold pending further information from the City Council.