While EE was walking on the backside of the belt storage unit near 10 LML, EE walked RT foot into a unseen hole due to excessive fine dust. EE continued walking stepping with the LT Foot into another unseen hole causing the EE to feel pain in the lower back restrictions: no lifting, carrying over 20 lbs, no pushing/pulling over 20 lbs, no climbing, no stooping, no crouching.