The two construction companies have both been fined £1.4m after a worker’s foot was trapped in a rotating screw, leading to the amputation of three toes.
The accident occurred on 5 March 2015, at United Utilities’ waste water treatment works on Eaton Lane, Tarporley.
Costain and Galliford Try Building were part of a joint venture which acted as principal contractor on a project to upgrade the infrastructure on site.
An investigation by the Health & Safety Executive found that both companies had failed to properly plan and manage the commissioning work.
The companies were this week found guilty at Liverpool Crown Court of breaching Section 3 (1) of the Health and Safety at Work Act 1974. They were fined £1.4m each, with a total of £101,046.20 costs.
Speaking after the case, HSE inspector David Argument said: “This injury was easily preventable. The commissioning work should have been properly planned and managed.
“Employers should make sure they properly assess and apply effective control measures to minimise the risk posed by dangerous parts of machinery.”