INJURED WAS INVOLVED IN A BI-ANNUAL MSHA INSPECTION IN THE BASEMENT OF THE PLANT PUMPHOUSE WHEN HE SLIPPED ON MUD TWISTING HIS KNEE. AS HE ATTEMPTED TO CATCH HIMSELF, HE ALSO STRAINED HIS SHOU LDER. DID NOT BECOME REPORTABLE UNTIL HE STARTEDMISSING WORK DUE TO SURGERY ON 12/21/01. HAS RETURNED TO WORK, BUT IS SCHEDULED FOR KNEE SURGERYON 1/18/02.