Prosecutor Stephen Mooney said: "Mr Phillips' perception was that this work needed to be done quickly and cheaply but not safely. He was completely ambivalent to the use of safety measures and so he walked away."
Passing sentence at Bristol Crown Court on 22 March, Mr Justice Dingemans said: "As a result of the completely inadequate steps of the defendant to safeguard [Clements'] safety the hole collapsed completely burying him.
"A particularly sad feature of this case is that Ryan Clements saw his father buried. I am sure there was plain and obvious risk of death from the collapse of the side of the trench."
Crawford's legal representative, Richard Smith, said the incident was "out of character with the way he would normally do his work, which was usually of a high standard".