Council highlights dangers of disposing treated wood

Christchurch City Council is asking residents to place all building material scraps, processed (either treated or machined) wood, off-cuts and residues such as sawdust and cold ash into their red rubbish bins, not their green organics or yellow recycling bins.

The request comes after analysis of the kerbside organics bin compost, which was shown to have high levels of metal compounds including copper, chromium and arsenic.

Machined wood can be treated with a range of preservatives to prolong its life as it is used for outdoor purposes, but it is difficult to identify whether the wood has or has not been treated to prolong its life from fungicides, pesticides, retard fire or to protect it from ultra violet light.

City Water and Waste Manager Mark Christison, says this is not only a problem for public health if the wood is burned, and for air pollution, but it also contaminates organic material put out for collection.

“It only takes a tiny amount of chemical residue in treated wood, cold ash or sawdust in one organics wheelie bin to contaminate a whole truck load of organic material, which may result in the material having to be sent for landfill,” he says.

When treated wood and its residues are placed in a green organics wheelie bin, there is a risk that high concentrations of chemicals can enter the food chain, whether they appear in home-made compost or in the Council’s own organics waste stream.

Mr Christison says it is important for residents to be mindful of this when disposing of building materials and particularly treated wood products.

“The message from the Council is to be safe - place all machined and treated wood, ash and sawdust in your red rubbish bin. These chemicals can be harmful if not disposed of in the correct way.”