A drainage apparatus comprises a support device including a support segment defining a clamp path, a first clamp member and a second clamp member. At least the second clamp member is configured to be coupled to the support segment while being free to translate along the clamp path. The drainage apparatus further includes a wedge including a drive axis, a first edge and a second edge. The wedge is tapered along the drive axis between the first edge and the second edge, and the wedge is configured to be driven in a direction of the drive axis into a locked orientation of the support device.