EE WAS DISCONNECTING A WELDER FROM A PICKUP AS TWO EMPLOYEES WERE SHOVELING ON TOP OF THE HOPPER. DURING THEIR SHOVELING A 4"" X 8"" ROCK ROLLED DOWN AND STRUCK EE ON THE LEG. HE WAS TRANSPORTED TO THE ER WHERE A LACERATION WAS MADE TO DRAIN THE CONTUSION. THE EE WAS HOSPITALIZED OVERNIGHT AND RELEASED ON 3-17-2000. HE REMAINS OFF WORK UNTIL 3/23 AT WHICH TIME HE WILL BE RE-EXAMINED