A unplanned roof fall occured in the #2 entry on the #2 section, in the #2 entry 500' from active face. Fall measured 20' L. X 20' W. X 5' Thick. No Eq. or injuries. Roof Fall did not affect ventilation and or passage of persons. The fall will not be rehab. Area was developed 9/10/10. Roof support consisted of resin roof bolts. Federal and State agencies notified immediately.