A sawmill’s decade-long environmental journey reaches another milestone this month as work starts on new drying kilns powered by sawdust.

Cutting down trees sounds more like an environmental problem, but the team at Kaituna Sawmill, northwest of Blenheim, are dedicated to making the timber business as sustainable and eco-friendly as possible.

General manager Tracy Goss says forestry produces a highly renewable material, and his sawmill does it with minimal waste and an ever-shrinking carbon footprint.

Ever since the sawmill started measuring emissions about a decade ago, the team has been on a mission reduce them.

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OneFortyOne, which owns the sawmill and multiple forestry blocks in Marlborough, Nelson and Tasman, as well as South Australia, has committed $11 million dollars to the Kaituna Sawmill for a three-year project starting this month, for new equipment that will increase how much timber can be dried and treated onsite.

Goss says the investment is the first major one from OneFortyOne since it bought the sawmill in 2018.

Kaituna Sawmill’s capacity has grown 40 per cent in the last two years, and they added eight staff to the team of nearly 90, to manage more logs after the Timberlink sawmill in Blenheim closed in 2020.

Demand for timber just keeps getting stronger, amid international shipping disruption and the domestic construction boom, causing a materials shortage and a jump in the price of lumber.

About 70 per cent of the sawmill’s timber is sold domestically, a switch from pre-Covid when it was about 75 per cent exported.

“We just can’t supply enough, domestically ... we are already working extra days,” Goss says.

However, there’s plenty of room to expand the sawmill. It processes between 150,000 and 200,000 logs a year, but has resource consent to process up to 500,000.

OneFortyOne manages about 80,000 hectares of certified sustainable plantation forests in Marlborough, Nelson and Tasman.

Each growing tree captures huge amounts of carbon over their roughly 30-year lifespan, until they are felled and start the journey from log to lumber. Every harvested tree is replanted.

Truck and trailers bring raw logs to the sawmill, where a loader picks them up with a mechanical claw and deposits them onto a conveyer belt, and the bark is stripped, destined to be sold as garden mulch and bark.

Grader Elliot Papps sits at the controls watching the logs arrive, and decides by sight what size boards to cut from each log, sending it to the right saw. It requires intense focus, and he takes three breaks a day.

But as part of the $11m project, a Transverse High Grader (THG) will be installed in January 2023 to make that decision instead of graders like Papps.

The scanning software “sees” the log with cameras, assesses the log’s weight, density and size, identifies any knots, twists or bark pockets in the wood, and analyses the best boards to cut from each log.

“And that will be much more accurate using this technology, it will be making decisions based on the log’s geometric profile,” Goss says.

Where a worker spent an average of 42 seconds per log, the THG scanner makes decisions in a fraction of the time. The worker instead oversees the scanner, and looks for ways to “optimise the cut”.

“By purchasing new equipment, we will be able to extract greater value from each log, meaning more local timber can be produced for New Zealand’s housing market.”

All the leftover chips and pieces are turned into sawdust, but they produce more sawdust than they can use – in fact about 3000 extra tonnes per year.

Once the timber is cut, it is stacked into loads destined for the Continuous Drying Kiln, on a track that slowly moves the timber through the kiln over roughly a minute.

Three new kilns will be installed, one in June and two more later in the year, which will allow the mill to bypass a step of the process that used to mean trucking timber to Christchurch for drying and treating.

That will take 20 trucks off the roads each month, and reduce the sawmill’s annual emissions by 9 per cent, Goss says.

That will be on top of its 46 per cent reduction in greenhouse gas emissions in the last decade, mainly thanks to the state-of-the-art Polytechnik energy centre installed in 2016.

Instead of burning waste oil to power the kiln, the sawmill now burns its own wet sawdust and uses the steam to power the kilns.

“We were burning about $500,000 in waste oil a year, so it’s a reduction in cost as well as in footprint.

“And we get 100 per cent out of our lumber now, the maximum efficiency we can.”

OneFortyOne supports environmental projects outside the sawmill too, partnering with the Cawthron Institute to research sediment in waterways from forestry harvesting, and partnering with the Marlborough Falcon Conservation Trust to rescue any kārearea nests or chicks found in forestry blocks, as well as supporting research on climate change and firefighting.

The sawmill was also named winner of the forestry section of the Cawthron Marlborough Environment Awards last year, with judges lauding the continuous improvement model, and hoping other businesses would be inspired to start a similar journey.

Climate Change Minister James Shaw, visiting the site following the award, commended the efficiency of the operation, and the “quite astonishing technology” allowing maximum waste capture onsite.

Kaikōura MP Stuart Smith says alongside the environmental benefits, there are also benefits for the regional economy, with the $11m project creating four new jobs, and increasing the amount of timber available for the domestic construction industry. “It is the ultimate in sustainability.”

And with so much sawdust stacked at the site, which will likely increase as they produce more timber, Goss says he is keen to help other industries make their own transition to cleaner sources of energy.

“Our chip and excess sawdust represent real opportunities. We are always interested in collaborating to achieve value and reduce waste.”