Fonterra silos repaired but no definitive cause found
Fonterra is putting a positive spin on the milk silo collapse at its Edendale plant in Southland, saying it has been repaired in half the time expected.
The Edendale plant was damaged last month, when it was estimated it could take six weeks to remedy the damage, but the work was done in three weeks.
The cause of the collapse continues to occupy the minds of investigators, who have also discovered cracks in the welding of four other silos - three more at Edendale and one at Clandeboye near Timaru.
Robert Spurway, Fonterra's chief operating officer global operations, said several factors in combination contributed to the collapse.
"The most significant was the cracking of the weld between the silo and the skirt which it sits on.
"As a precaution, we undertook inspections around the country on silos of a similar age and design. While the majority of our silos are unaffected, minor cracking was identified in the welds at a small number of silos at Edendale and on one silo at our Clandeboye site," Spurway said.
The welds had all been replaced and all work signed off by independent contractors "so that we can be confident that our silos are structurally sound".
The cause of the cracking was still being investigated.
"Silos face different pressures depending on a wide range of factors such as ground vibration, wind and exposure to the elements and these factors are being considered.
"We have fitted strain gauges to the repaired silos at Edendale to provide us with real-time data on the various pressures these silos experience," Spurway said.
A Fonterra spokesman said the co-operative would not reveal the cost of the operation and associated remedial action. For example, some milk which was destined for Edendale has had to be trucked north to other plants for processing.
He said Fonterra normally moved milk around the country to the places where it was wanted in order to make a particular product, and therefore diverting the milk from Edendale was not an issue.
Poor performing Christchurch company Mercer Group designed and built all five of the silos, as well as a number of others. Fonterra has more than 1000 throughout the country.
The silo investigation at Edendale will determine if Mercer faces any "material outcome".
Fonterra said it had been working with WorkSafe and the University of Auckland, and sharing what it had learned with other manufacturers and industries.
* Audio courtesy of RNZ