ON 10/12/03, BETWEEN 3:00 & 11:30 P.M., EMPLOYEE WAS STACKING 100 LB. BAGS OF GROUND CALCIUM CARBONATE (LIMESTONE). HE AWOKE ON 10/13 WITH A PROTRUTION IN THE NAVEL AREA OF HIS STOMACH AND CAL LED HIS SUPERVISOR TO REPORT THE PROBLEM. EMPLOYEE STATES THAT HE DIDN'T STRAIN HIMSELF OR FEEL ANY PAIN ON 10/12. HE WAS SENT TO DOCTOR WHO DIAGNOSED AN UMBILICAL HERNIA.