Cyclone Gabrielle: What’s happening with Hawke’s Bay silt? Contractor says it can be repurposed

Brendon Mallia, managing director of Composting New Zealand clears silt in Pakowhai. Photo / Paul Taylor

A contractor working in Hawke’s Bay says it will take time and processing but the piles of silt and wood debris left behind by Cyclone Gabrielle can be used for composting and earthworks.

Brendon Mallia, managing director of Composting New Zealand LTD, came to Hawke’s Bay from Kapiti Coast after Cyclone Gabrielle to help with the cleanup.

Mallia said Hawke’s Bay had handled a disaster of this scale better than some other regions would have, helped by the fact that Napier and Hastings have a tidy landfill run well by experienced staff.

“If you go to my part of the world on Kapiti Coast, we rely on a silly little transfer station and then our rubbish is an hour and a half cart all the way to Bonny Glen,” Mallia said.

“If you imagine having this situation on the Kapiti Coast, an hour and a half, and they can only cope with so many trucks on a daily basis, we would be buggered.”

He said a lot of his work involved taking silt, logs and wood debris and repurposing it and he had been advising businesses how to process silt into a usable product, based on his decades of experience in the Wellington region.

Mallia said mixing carbon, or organic matter, in the silt will break it down into a useable product.

“You basically end up with a very good topsoil.”

He said even contaminated silt like that found at Awatoto could be repurposed, using organic material.

“It’s like the KFC recipe, you need to put a lot of herbs and spices into it. Mix it all up and either cook it, process it, whatever you want to do, you can turn it from something that is not useful into something that is useful,” he said.

“There is always a solution to these problems, but sometimes it takes a bit of time.”

He said silt was being stockpiled in the meantime and while he couldn’t say what the councils’ plans for it were he understood there were some ideas for what to use it for.

He said logs and wet wood debris could be mulched and effectively repurposed into compost with sand and silt.

“You put it in with silt and sand and it naturally decomposes. When it decomposes, it becomes a compost,” he said.

“You mulch that material, you pull it into that stockpile of sands and silts, and you have a reasonably good soil structure.”

He said the administration team from local councils deserved recognition for their hard work and how efficient their response has been during the clean-up and recovery efforts.

“Putting good environmental policy in place in the past has helped big time,” he said.

“I can honestly say they have worked overtime, well and truly outside of their hours of normal work.”