An idea to renovate Joplin’s Memorial Hall as a convention center and perhaps add an arena that could cost up to $45 million was outlined Monday night for the City Council. A suggestion to study future uses for the hall was made by the city’s parks and recreation director, Chris Cotten; the assistant director, Scott Garrie; and director of the Joplin Convention and Visitors Bureau, Patrick Tuttle. The council took no action after the presentation.