Biochemist concerned over possible emissions

‘‘It’s not going to be the same, batch on batch. It’s like cooking a cake. Sometimes it rises, sometimes it doesn’t. Therefore, they need monitoring.’’ Dr John Fullerton

A biochemist who specialises in human physiology has described a plan to build a pyrolysis plant in a residential area as ‘‘frightening’’.

The pyrolysis plant is proposed as a way to get rid of copper chrome arsenic (Cca)-treated vineyard posts stockpiled in Marlborough, by turning them into charcoal to be sold commercially.

Waste Transformation has lodged a resource consent application to build a pyrolysis plant beside the Bluegums Landfill on Taylor Pass Rd, on the southern edge of Blenheim.

But nearby resident Dr John Fullerton, who spent the last 40 years working in peer-reviewed biochemistry research, said the plant should not be located near homes.

‘‘I’m not a NIMBY [not in my backyard] by any means. If all they were doing was burning untreated timber, I would have nothing to say about it. Pyrolysis is a very useful technology,’’ Fullerton said.

‘‘But people don’t seem to understand why arsenic emissions are a problem. It’s not only people living here, it’s organic winegrowers too. They’re going to lose their certification. It’s frightening. It scares the living daylights out of me.’’

Waste Transformation chief executive Mike Henare said last year words such as ‘pyrolysis’ and ‘arsenic’, had stirred residents into a frenzy, but said the science was on his side.

Fullerton said he did not believe the company fully ‘‘understood the science’’.

Waste Transformation commissioned a study by Massey University to model the emissions from the plant. A summary of that study included in the resource consent said the plant would release on average 20 grams of arsenic into the air each day.

Henare said that rate was modelled using a worst-case scenario and was still ‘‘well below health and safety standards’’.

Fullerton said it was impossible to calculate an accurate rate level given the vast range of variables that could cause fluctuation in arsenic emission levels.

Those variables included temperature, pressure, the amount of CCA in the wood, and the size and density of each piece of wood.

Fullerton produced five peerreviewed scientific studies that showed pyrolysis of Cca-treated timber released ‘‘substantial’’ amounts of arsenic, at levels that were difficult to control.

‘‘It’s not going to be the same, batch on batch. It’s like cooking a cake. Sometimes it rises, sometimes it doesn’t. Therefore, they need monitoring. And it’s got to be daily or weekly,’’ Fullerton said. Henare said he had considered including a monitoring system in the proposal, but decided against it because the amount of arsenic in emissions was so low, and such a system would be ‘‘very expensive’’.

He said his system could control the variables that could affect arsenic emission levels, but would not go into detail, citing commercial sensitivity.

‘‘I can say, however, the main variables impacting arsenic emissions is operating temperature and volume of CCA. Our system is a batch process and described as controlled low-temperature pyrolysis. These design parameters are specifically used to lessen the variables of the process when dealing with difficult waste streams.’’

Fullerton suggested Waste Transformation consider a different location. ‘‘I would be less concerned if they put it on the coast, where the arsenic could all just blow out to sea.

‘‘Arsenic hangs about and builds up. And if you’re getting kilogram quantities pumped out each year, and it falls on your garden, it will be building up inside you.’’

Henare said the site beside the landfill was chosen because it already had infrastructure the plant could use, bringing down the cost of running the plant.

‘‘Transport is the biggest cost in waste, so the less distance it has to be moved, the better.’’

After Waste Transformation filed the application, the council asked for more information about arsenic emissions, including whether arsenic would be deposited into soil and plants, and suggested doing a health risk assessment. Henare confirmed on Friday he had responded to that request.

A council spokeswoman said the application was in the process of being publicly notified.