The federal safety authority is yet to release a statement on the decision but has made a preliminary report of the accident available.
According to the report, 87-year-old Samuel Vignoli died on July 3 at the Maple Creek preparation plant in Washington, Pennsylvania, when the skid loader he was riding while mowing an embankment slid into an impoundment.
MSHA said the reason the mower slid down the embankment was unknown.
“The victim appeared to be mowing the embankment in a vertical direction between nine to 11 feet in length from the level road on top of the impoundment's breast down toward the body of water,” MSHA said.
The report stated that Vignoli was a contractor at the mine who had been performing the work for 23 days.
Vignoli’s body was recovered but the machine is still in the impoundment's waters.
MSHA has classified the death as drowning.
The Maple Creek preparation plant is operated by Maple Creek Mining and owned by Robert Murray.
MSHA can back charge fatalities following preliminary reviews of accidents when appropriate.