"The worker remained trapped in the conveyor for several hours until emergency services were able to free the remains of his arm, which was later amputated in hospital,'' said Jean Martin of the Government's labour group.
A labour group investigation found the accident could have been avoided if the company had put in place adequate machine guarding, carried out regular hazard checks, and put in place safe operating procedures for using the machinery.
"This worker experienced injury and trauma that no person should ever be subjected too,'' said Ms Martin.
Canterbury Greenwaste Processors and Mr Kepple were charged under Section 6 of the Health and Safety in Employment Act for failing to take all practicable steps to ensure workplace safety.
"The (labour group) has a nationwide compliance project underway to reduce the unacceptably high level of fatal and serious harm injuries associated with the unsafe use of machinery.
"We expect all employers to take the minimum steps required to prevent harm to their employee - particularly where exposed machinery is concerned. Unfortunately, (the labour group's) investigation into the incident found that Greenwaste and one of its directors had failed to do so,'' she said.
Greenwaste Processors Ltd could not be reached for comment.