*Survey station is placed on the centre line of the proposed heading. The theodolite is set up so that the optical axis is in the required grade plane.
* The grade plane is reduced to its equivalent angle & set in the theodolite, which is then brought to the bearing of the proposed heading.
* This point, which is constrained in both the vertical & horizontal planes, is then marked on the face & becomes the target for the MTL alignment laser.
* The theodolite is then reversed or plunged & pointed at the backsight position. The vertical angle here will be the opposite sign of the vertical angle for the heading.
* The theodolite laser thus marks the reference point on the backsight that must be occupied by the MTL. A 18 mm diameter drill bit is then collared on the laser spot & the drill is brought into the correct attitude by aligning a mark on the handle with the theodolite laser. A hole is drilled approx. 200 mm & flushed clear of cuttings.
* A length of PVC pipe (16 mm OD, 10mm ID) with the back end sealed, is inserted in the hole. This becomes the permanent housing for the MTL. The laser is turned on & inserted into the PVC pipe. A check is made to make sure that the MTL can be aligned to the target.
* The PVC pipe & laser are removed & the hole is 1/3 filled with chemical grout. The pipe & laser are reinserted so that the pipe is flush to the rock surface.
* As the grout cures, it may move the pipe slightly, so the laser and the laser dot should be resurveyed.
* The final bearing & dip as described by the MTL1 is calculated & recorded.
* The pipe is locked into position by the cured grout & is ready for subsequent use