When approached to assess the restoration of the existing ventilation system at the Powell Street Station on the BART (Bay Area Rapid Transit System), we had to consider many factors including the condition of the equipment, changes to codes and regulations since the original design in the early seventies and the condition of the distribution systems including the presence of any harmful substances. Following the assessment we deemed it may be more effective and cost efficient to replace the system, so we then had to consider recommendations for new sizing criteria, specifications for new equipment and how new controls would be integrated into a modern mass transit network. This paper gives an overview of the key points in both processes, and explains how recommendations were made to maintain adequate station operations both now, and in the future.