Vineyard posts a 'charcoal' grey area as council considers stockpile log
The wine industry should protect New Zealand's clean, green image by ditching chemically-treated vineyard posts, a Marlborough councillor says.
Marlborough has more than 12.5 million vineyard posts spread over 22,000 hectares, and nearly all of them are treated with copper, chromium and arsenic.
Thousands of posts are stockpiled around the region, and lingering traces of chemicals may be dangerous if vineyards are rezoned into residential areas.
The Marlborough District Council voted at their last full council meeting to help fund a hi-tech timber recycling plant to turn treated and untreated timber into charcoal.
The council's environment committee is also considering a proposal to make vineyards keep a record of where they stock the posts, and how large the stockpiles are.
Councillor Gerald Hope, also chairman of the Marlborough Research Centre, said although CCA-treated posts were the most cost-effective he wanted to see the wine industry use different materials, such as "environmentally benign" durable wood rather than treated timber.
"I think it would reflect well on New Zealand more widely," he said.
Already posts made from different strains of eucalyptus tree were being trialled in Marlborough to see how they would last, and they would be inspected this year to see how suitable they would be, Hope said.
Organically-certified Seresin Estate was already using natural timber vineyard posts, and winemaker Clive Dougall said while they were slightly more expensive the vineyard was happy with them.
"We are really, really excited to have an alternative to having metal posts or concrete posts, or plastic posts in the ground," he said.
"They are a straightforward substitution for the arsenic posts."
Replacing their broken CCA-treated posts with untreated posts allowed Seresin to keep exporting to the United States as an organic wine brand, Dougall said.
DEALING WITH CCA POSTS
Marlborough had more than 22,000 hectares of vineyards, with about 550 posts being used per hectare.
Thousands of CCA posts broke every year and had to be disposed of, and new posts which had not yet been used were also often stored at the vineyards for months or years.
Arsenic concentrations in the soil beneath stacks of new CCA vineyard posts were about five times higher than the National Environmental Soil Contaminant Standard, a report prepared for the council's environment committee said.
The risk to people working in the vicinity of dumped posts was relatively low.
"However if the areas of vineyard currently used for storing new and old timber posts were to change to a more sensitive land use scenario, such as residential, then the concentrations present would represent a significant risk to human health," the report said.
Treated timber could also pose a risk to local groundwater resources and surface water, depending on the geology of the area, the report said.
CCA treatment had been banned or restricted in Europe, Canada, and a number of other countries.
Hope said realistically even if the land was later used for housing the risk of illness due to CCA timber having been stored or used there was small. The danger was highest when workers were handling new posts.
The council would discuss identifying and recording the locations of "bulk post piles" at the next environment committee on March 16.
The pyrolysis timber recycling plant, to be created in partnership with company Waste Transformation Ltd, was estimated to cost the council $450,000.
The company would provide infrastructure, the plant, and equipment to the value of $1m, while the council would provide a site with car parking, utility connections and fencing.
Council solid waste manager Alec McNeil said the next step would be for Waste Transformation Ltd to apply to the council for a resource consent.
The charcoal product would be processed and sold locally as coal replacement or overseas as carbon black, used to make industrial products such as car tyres, bringing the council about $90,000 a year.
That figure would help fund the cost of the plant, and the end cost for the council was predicted to be only $14,700 a year.
Wine Marlborough general manager Marcus Pickens said he supported the plant, and the grapegrowing community supported environmentally-friendly alternatives to CCA posts.
However, the cost of alternative options and sources of supply had to be considered, he said.
- The Marlborough Express