Three days after a worker died at the Lafarge Canada asphalt production plant on Moodie Drive, the company will be in court today on safety and health charges related to a fatality last year at another Ottawa site.   The company was charged last month by the provincial Ministry of Labour with two infractions under the Occupational Health and Safety Act in connection with the May 3, 2005, death of Andre Potvin of Gatineau. The 60-year-old man died after falling into a cement-making mixture in a hopper at the company’s Star Top Road plant.  The court appearance comes as the company deals with the death of Kent Walker, 61, who fell more than six metres Monday to the bottom of a storage container at the Moodie Drive site between West Hunt Club and Fallowfield roads.  The ministry is still investigating that incident.