The U.S. Labor Department's Occupational Safety and Health Administration has cited a Chinatown-based construction company, saying it failed to protect its workers building new multi-family housing on the 900 block of Arch Street from falling or from hazardous conditions while working in a trench on June 10. In its citation, issued Nov. 9, OSHA proposed penalties of $72,511. OSHA said the company, Hua Da Construction, also located on the 900 block of Arch Street, had been cited for unsafe conditions in March and May. No one was immediately available to comment.