It will be 264,000 sq ft and costs $243mn. It's also going to include renovation of the historic Fire Station #30 (which will become a 25,000 sq ft community room). In an article about the building, CurbedSF writes: "The PSB was ordered after the current home of the SFPD Command Center at The Hall of Justice was deemed unsafe in the event of a large earthquake. Money for the new PSB was secured through the Earthquake Safety and Emergency Bond of 2010 and it is being designed to very strict standards in hopes of surviving even the mightiest of quakes. In addition the structure is seeking LEED Gold certification, with occupancy expected ready in March 2014." The idea is that police and fire can continue to operate after an earthquake - the building is supposed to be functional for up to a few days even when everything else is falling apart!
The official site for the project is at http://buildsfpsb.com/