Vincent Talbot, 47, from Lincoln, suffered serious leg injuries when he was crushed in the incident at Fleet Street, Holbeach, Lincolnshire on 9 March 2012.
He was trapped in the trench for 15 minutes before being extracted by the fire and rescue service and then airlifted to hospital.
His right ankle has been left permanently damaged, pointing 10 degrees off line. He was off work for more than a year and vowed never to work in a trench again.
An HSE investigation found insufficient measures were taken to protect those working in trench, and a series of safety errors had led to the collapse.
Principal contractor, Kier MG Ltd, was appointed by Lincolnshire County Council to install new storm drains.
The accident happened before Kier acquired May Gurney in 2013.
Kier MG Ltd subcontracted the installation work to John Henry & Sons (Civil Engineers) Ltd, who subsequently further sub-contracted the work to Lawless Civils Ltd.
Talbot was a self- employed contractor hired by Lawless Civils Ltd.
John Henry & Sons (Civil Engineers) Ltd, failed to inform Kier MG of the appointment of Lawless Civils Ltd.
Lawless were approved contractors of Kier MG but not approved for this type of specialist excavation work.
Lawless appointed a supervisor who had never supervised work, he did not have the relevant training and qualifications to do so.
After the accident John Henry & Sons (Civil Engineers) Ltd, backdated the method statement to give the impression that it was signed by the workers prior to the trench collapsing.
A three-metre long trench box shielded workers but the pipes being laid in the trench were six metres long, meaning workers weren’t protected over the length of the pipe.
Other trench support systems such as trench sheeting were not used, and the unsupported trench had water leaking into it.
The trench had been left open overnight and concrete was being used to bed the pipes in at the bottom of the trench, instead of pea gravel as specified by the client.
Water mixed with the concrete, making the pipe levelling process extremely difficult as the level of the pipe bed had to be continuously adjusted.
When Talbot was attempting to level a pipe section for a second time, the sides of the trench collapsed and trapped him.
Kier MG Ltd (formerly known as May Gurney Ltd) of Sandy, Bedfordshire, pleaded guilty to breaching the CDM regulations and were fined £1.5m and ordered to pay £23,327.83 costs.
John Henry & Sons (Civil Engineers) Ltd of, Cambridge denied the charge but was found guilty of a safety breach. They were fined £550,000 and ordered to pay £166,217.86.
Lawless Civils Ltd of Lincoln, pleaded guilty to safety breaches and were fined £40,500 and ordered to pay costs of £53,346.59.
John Edwards, Kier Group Safety, Health, Environment and Assurance Director said: “This incident happened in 2012 and before Kier acquired May Gurney in 2013.
“Since the acquisition, the safety performance of May Gurney has improved significantly, with the Accident Incidence Rate reducing from 736 to 226.
“Operating a safe and sustainable business is Kier’s number one priority. We have developed an industry-leading reputation for our rigorous approach to managing safety issues and for developing new approaches to safe working.
“We maintain our focus on the continuous improvement of safety standards.”
HSE inspector Martin Waring said: “This incident was foreseeable and avoidable and Mr Talbot’s injuries were the result of multiple failings by the duty holders, from the planning stage through to the execution of the project, resulting in the inevitable collapse of an unsupported trench. Sufficient trench support systems were not provided.
“Even while the excavation phase had begun, a catalogue of errors and omissions led to the injuries of Vincent Talbot.
“It is inevitable that at some time an unsupported trench will collapse, for this reason safe systems of work, should be in place in order to protect persons who work in trenches. We could easily have been dealing with a fatal incident.”