ST. LOUIS (AP) - Crews have completed the most critical phase of removing bedrock that threatened barges along a crucial stretch of the drought-starved Mississippi River in southern Illinois. The work by contractors hired by the U.S. Army Corps of Engineers has staved off the shipping industry's fears that the treacherous channel could close to traffic. Using excavators and explosives, workers added two vital feet of depth to the channel about 130 miles south of St. Louis.