Facebook is planning to start construction on a third data center in Prineville, Oregon. The company filed plans for a data center measuring about 62,000 sq ft with the city, the Associated Press reported.

The company preparing to start construction on a third data center at its site in the rural town while its second one is still under construction is a sign of rapid growth of its social network’s user base, which needs to be supported by an infrastructure of appropriate capacity.

Facebook spokesman Lee Weinstein told AP that plans for the third data center had been in place for some time.

“Facebook decides when and if to build additional structures as business needs dictate,” he said. “This building has always been on the drawing board.”

Facebook’s first data center in Prineville measures more than 300,000 sq ft, and it is building a second identical one at the site.

Since the social-network company built its first data center in Prineville, Apple has announced it would build one too, and there have been reports that a third company was considering the town as a data center site. Other companies with large data centers in the surrounding region include Microsoft, Google, Amazon, Dell and Yahoo!.

Pacific Power, the utility company serving Prineville, has been preparing to accommodate more data centers by upgrading its electrical substation there. It said in March it would accelerate the project to add 400MW of capacity to the substation, pushing the target completion date from June 2013 to January 2013.

Silicon Valley-based electrical engineering and construction company Cupertino Electric, which does a lot of data center work, has recently opened an office in Prineville, planning to serve its existing customers in the region (including Facebook) and new ones expected to build data centers there.

Other Facebook-owned data centers are located in Forest City, North Carolina and Lulea, Sweden. The company also leases data center space from commercial providers on the US east and west coasts.