Facebook is again expanding a data center it is building in the Omaha suburbs. The social media giant said Wednesday that it will spend an additional $400 million to add another 1 million square feet to the data center that is partly operational southwest of Omaha in Sarpy County. The company estimates that it will spend nearly $1.5 billion total on the project that will now expand from Papillion into Springfield and include 3.6 million square feet. When the project is completed in 2024, Facebook said the data center will employ roughly 300 people. The area already includes data centers for Google, Yahoo, Travelers Insurance and Fidelity Investments.