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JENNIFER EDER are a number of potential uses for it.’’
Council solid waste manager Alec Mcneil said his team had been monitoring the amount of wood-only loads dumped over the 2017-2018 financial year to date.
The viticulture industry had dumped 517 tonnes, or 22 per cent, while the construction industry dumped 160 tonnes of mostly treated wood from ‘‘house building sites’’, at 7 per cent of the total amount of wood dumped.
The vast majority of wood, treated and untreated, was dumped in mixed loads and sorted at the Waste Sorting Centre, and accounted for 1687 tonnes, or 71 per cent.
‘‘We get thousands of tonnes of wood in the general waste stream,’’ Mcneil said.
‘‘Most of it is coming from general economic activity. Treated timber is pervasive across the community. It’s not quite the scourge of plastic, but we’re producing a lot of treated wood waste, especially with the building boom here.
‘‘It’s in fencing, in trusses, in farming posts. All of that is treated timber by its very nature. It faces the same challenges associated with vineyard posts, as it has to stand up to the elements and that’s why it’s treated.’’
However, the viticulture industry’s contribution would be more than 22 per cent if the stockpiled posts were included, Mcneil said.
‘‘[The pyrolysis plant] is going to solve a problem for the vineyards, but they are not alone in needing it.’’
Vineyard posts and some types of wood used in construction were treated with a chemical compound called copper chrome arsenic, or CCA, to stop them rotting in the ground.
Bluegums Landfill was lined so any leachate from Cca-treated timber at the dump would run into a collection system rather than seep into the ground, Mcneil said. If all timber going to landfill was pyrolysed, it would extend the life of the Bluegums Landfill by about 13 years, Mcneil said.
‘‘But that’s not the only reason for doing it. There is a secondary use for the pyrolysed product, rather than just burying the wood in the ground. Wood doesn’t biodegrade that quickly, and treated timber is going to be there for quite a long time.’’
Waste Transformation Ltd intended to sell the charcoal to commercial buyers.
Residents who lived near the proposed site opposed the plant because they feared arsenic emissions from the plant would affect their health.
Neighbour and biochemist Dr John Fullarton said there was some pressure on the construction industry to consider alternatives to CCA treatment for wood, which had been banned in other countries.
‘‘The issue is often raised when you get bushfires in Australia that burn down domestic houses built with treated timber. The people are then told they’ve got toxic ash on their property, which can be problematic to get rid of. That’s an extreme example, but there are pressures out there to try using a different type of wood,’’ Fullarton said.
‘‘But CCA use goes back to the 1930s. It’s worked for years and years. There’s no risk to the public in using it for fencing or decking as the chemicals are bound to the wood, although you do get a bit of leaching into the ground.’’
If waste disposal companies started charging a fee for taking Cca-treated timber, that would motivate the industry to consider other options, such as heattreatment, he said.
‘‘Cost and commercial pressures would push people away from using it. If heat-treated wood could be made and sold cheaper, pyrolysis would be a great option for disposing of it, and we could cut down the amount of timber going to landfill significantly.’’ Should Market St, in Blenheim, become a car-free zone?
‘‘Trial it for six months, if it doesn’t work, change it back.’’