A quarry owner claims criminals have caused more than £41,000 worth of damage to his equipment.
Barry Dring is offering an £8,500 reward for information leading to the arrest and conviction of the person or people responsible for committing the damage at Butts Quarry in Ashover.
Mr Dring said fine sand was put into the engines of three machines which are used to carry out maintenance at the site.
The 50-year-old – who bought the quarry last July – said he believes the crime was committed sometime over the Christmas period.
He told the Derbyshire Times: “We were servicing the machines earlier this month after the Christmas break and they went bang.
“Fine sand was put into the machines’ engines.
“It appears whoever did this knew what they were doing.
“I feel sick about it.
“I’ve worked hard since the age of 18.
“Why do this to me?”
The quarry is used as a popular motorcross track.
One motorcross website describes it as having a ‘hilly, exciting, natural terrain’.
Mr Dring added: “This is a massive setback for my business because the machines were used to carry out important maintenance duties on the site.
“I won’t be ruined by it, though.
“I’m currently liaising with insurance companies so hopefully they will be able to help out.”
Mr Dring said he has also informed Derbyshire police about the incident.
He added: “I’ve got an £8,500 cash reward on offer for information leading to the arrest and conviction of the person or people responsible for doing what they did.
“If you think you can help, please call me on 07976810978.
“Any information received will be treated in strict confidence.
“I hope whoever did this will be found and justice will be served.”
Witnesses to the crime or anyone with information about it can also call police on 101 or Crimestoppers on 0800 555 111.