Description Blue Ballast Rubble 50mm is commonly used for large drainage/soakage pits, however can also be used in your garden for paths or driveways. Stone sizes are roughly 50mm in diameter. Also available in 30kg bags. Key Features of Blue Ballast: Used for drainage or soakage pits Used as a path or driveways Aproximately 50mm Rubble Delivery: Rubble and metals are sold by the tonne, and are available online or in-store. Delivery across Adelaide starting from just $35.