SPRAIN LEFT FOOT ONE WEEK MODIFIED DUTY. EE WAS ATTEMPTING TO DISLODGE PLUG OF ROCK IN A TRANSFER CHUTE CLIMBING UP AND DOWN A PORTABLE LADDER SEVERAL TIMES (APPROX 2 HRS). EE WAS WEARING RUBB ER BOOTS WITH WET SOCKS, WHICH PROBABLY CONTRIBUTED TO THE INJURY. DRY FOOT WEAR SHOULD HAVE BEEN WORN. TRAINING ON PROPER CLIMBING TECHNIQUES HAD BEEN GIVEN ON DEC 17, 1999. NO RULE BROKEN.