Expedia has long-term plan to greatly expand new campus

Expedia is working on a long-range master plan to expand allowed development on the travel giant’s new 41-acre waterfront campus to as much as 1.9 million square feet, an official said Thursday.

That would be almost half again as much as the 1.3 million square feet the city had approved for Amgen, the site’s former owner, and nearly three times the total of buildings now on the site.

The Bellevue-based company announced in the spring it had bought the former Amgen campus on the Seattle waterfront for $229 million and planned to move its headquarters by the end of 2018. The company at the time said it plans to have more than 4,500 employees there.

The campus now has six buildings and a parking…