The construction of tunnels leads to substantial alterations of the surrounding rock, which can be critical concerning safety aspects. We use different mobile methods to assess the hydromechanical properties of an excavation damaged zone (EDZ) in a claystone. We show that long-term exposure and dehydration preserve a notable fracture permeability and significantly increase strength and stiffness. The methods are suitable for on-site monitoring without any further disturbance of the rock.