The Conservation Commission on Thursday will meet to discuss construction of a 20-unit apartment building proposed for 77 and 79 Messenger Court. Robert Antonelli of Everett has filed plans showing the project would lie within a 100-foot buffer of wetlands. The commission must decide if the project complies with state environmental law and a city ordinance regarding wetlands. The meeting will be held at 7:45 p.m. in the mayor’s conference room at City Hall.