When a Ferry Dock is deleted, an area of cells remains that possess Contraband Dangers for the original Ferry Object (a Saw and a Screwdriver). These cells can be built over, but their Contraband Dangers remain. Furthermore, a Room designation cannot be placed on the afflicted cells.
Through the Intelligence menu, I have confirmed that Prisoners have the ability to steal contraband from these afflicted cells even if they have been built over with a foundation.
Through the Intelligence menu, I have confirmed that Prisoners have the ability to steal contraband from these afflicted cells even if they have been built over with a foundation.