Former South Carolina offensive lineman Jonathan Alston signed a three-year contract Monday with the Washington Redskins.

Alston, who was not drafted, participated in this past weekend’s rookie minicamp in Ashburn, Va., and will report May 16 for the team’s voluntary workouts.

“You have to go out there and prove yourself,” said Alston, a 6-foot-5, 302-pound lineman from Goose Creek.

The Redskins have a mandatory minicamp beginning June 16, and the team’s training camp starts in late July.

Alston’s agent, Philip Wickstrom, would not disclose the contract’s terms, but the NFL’s standard rookie free-agent contracts pay about $230,000 per season. NFL contracts are not guaranteed.

Alston, 22, was the Gamecocks’ starting right guard during the past two seasons after spending his first two as Travelle Wharton’s backup at left tackle.

Alston said he likely will play tackle for Washington, which needs depth at the position after Jon Jansen, the Redskins’ starting right tackle, missed the 2004 season with a ruptured Achilles tendon.