Parminder Singh, Manjinder Singh and Tarjinder Singh were dumping rubbish in a field in Trysull, near Wolverhampton, when they were disturbed in August last year.
Parminder panicked and drove off with Tarjinder - known by his nickname Lola - unsecured in the back of the van with no seats and the back door open.
The sudden movement caused Tarjinder to lose balance, fall out of the back of the Mercedes Sprinter and suffer a serious head injury as he landed in the road.
Parminder drove off, leaving Tarjinder seriously injured in the road as thunderstorms struck across the region.
Emergency services were called at around 11pm and the 49-year-old was found on Furnace Grange Road around 300 metres away from the junction with Ebstree Road. He was taken to hospital but died nine days later.
Parminder, 38 and of Arthur Street in Blakenhall, went on to admit causing death by careless driving and depositing controlled waste without a permit.
He has now been sentenced to eight months’ in prison, suspended for 18 months, 20 days community rehabilitation and given an electronic tag with orders to be at home between the hours of 7pm to 7am.
He was also disqualified from driving for two years, with a requirement to pass an extended retest, by a judge at Stafford Crown Court on Thursday.
Manjinder Singh, 34, of Lane Road, Lanesfield, was fined £1,600 for depositing controlled waste, which he had admitted belonged to him, without a permit.
Pc James Addison, from the Staffordshire and West Midlands Serious Collision Investigation Unit, said: “This was a tragic loss of life following the criminal activity of those involved in this incident. Had they not been dumping rubbish illegally this incident would not have occurred.
“By failing to ensure that Tarjinder was secure in the vehicle when he drove away, Parminder’s driving caused the victim to fall from the vehicle as it sped away.
"I extend my sympathies to the family of Tarjinder, who have been left devastated by the loss of their loved one in such avoidable circumstances.”