PITTSBURGH — The Coast Guard is responding to a report of a sheen on the Monogahela River following a vessel and barge grounding Tuesday. Watchstanders at Coast Guard Sector Ohio Valley received a call from Braddock Lock and Dam at approximately 4:30 p.m. and reported an oil sheen in the vicinity of a grounded barge. The uninspected towing vessel Carrie Mays was down bound with 14 empty barges at...