The 21-year-old has represented England at youth level and can operate as a centre back or right back.
The young defender has had some excellent performances for Everton's reserves this season and is nearing a future appearance in David Moyes's first team.
For the moment, O'Hanlon looks set to join the Second Division promotion-chasers on a month's loan, with the Wiltshire-based side currently in a the last play-off position.
