Complex sentence: Stage 2 in expansion began with planning for a new multipurpose building which will house two gymnasiums as a practice facility, located near the baseball diamond and across the driveway from the soccer practice field.
Split into simpler sentences: Stage 2 in expansion is under planning for a new Multipurpose building which will house two gymnasiums as a practice facility. The building is set to be located near the baseball diamond and across the driveway from the soccer practice field.