Roughly mark out an area large enough to accept the frame. Clear away any loose or flaky material within this area to leave a sound surface for the new mortar bed.
The level of the frame can be set with a straight edge from nearby finish if available or by string lines set to finish level, temporarily shim the frame to judge the depth of the mortar bed.
Position the frame on the mortar bed in its previously established location and carefully insert the cover. If the cover is to be locked the previously removed bolts should now be inserted, do not fully tighten at this stage.
Tamp down until the top of the cover and frame sits 2 to 3 mm below the finish floor line on all sides.
Check that the cover sits in the frame without rocking and that the top of the cover and frame are level, making any necessary adjustments to achieve a good fit.
Lay the paving in the cover on a 20 mm to 30 mm bed, this can be sharp sand, or for areas more frequently accessed or subject to heavier loadings a screed / mortar bed is recommended.
Gaps between the blocks must be fully filled with a proprietary grout to prevent movement.
Note: Unbound permeable paving grit does not provide a stable bed or fill between blocks within a steel cover and should not be used.