IC to provide a method statement on how they are going to carry the backfilling on top of the concrete slab protection and avoid any breaking of the slab.
IC can also reduce the sand cover on top of the pipe to 150 mm and cast the slab 150 mm above the sand cover and still maintain the 300mm of sub base material wherein first layer of 150 mm can be proof rolled only and the second layer can be properly compacted and tested to avoid any defects at a later stage 
