EMPLOYEE WAS TURNING THE WATER TRUCK AROUND AT THE END OF THE ROAD WHEN A COAL TRUCK CAME UP ON HIM WHILE EMPLOYEE WAS SIDEWAYS IN THE ROAD SO EMPLOYEE COASTED BACK TO GIVE THE TRUCK DRIVER MORE ROOM AND HIS BACK TIRES FELL OFF THE ROAD AND INTO A SUMP HOLE AREA AND ROLLED OVER ON IT'S SIDE.