Tonic Construction employee Shaun Carter, 29, was driving his forward-tipping dumper to the top of the mound of waste soil, stone and rock when it became stuck on the edge.
As Carter jumped out of the vehicle, it overturned and struck him on the head. He died at the scene from severe head injuries.
According to a report by the Gazette and Herald, Carter was part of a team putting in roads, drainage and foundations on a David Wilson Homes construction site in Cirencester, Gloucester, when the accident happened in May 2016.
An excavator driver had removed part of the spoil heap some days earlier leaving a steep, almost vertical, side. The heap had not been made safe and an investigation by the Health and Safety Executive (HSE) found it was common for dumpers to climb spoil heaps without barriers to prevent over-running.
Tonic Construction pleaded guilty to breaching reg 2(1) of the Health and Safety at Work Act. It was fined and ordered to pay costs of £5,565.
HSE inspector Sue Adsett said: "Risks associated with the creation of spoil heaps had not been suitably and sufficiently assessed.
"Either the company should have decided on a safer method which avoided the need for the dumper to access spoil heaps (as they have done after the accident), or they should have introduced stricter management arrangements which would have included bunds at a safe distance from the edge."