Mr Libeskind, who designed the Jewish Museum in Berlin, would like to keep much of the gaping hole left at the World Trade Center site for space for an eventual memorial.
States Works began temporary repairs at 07:00 BST by filling the hole in the road with rubble taken from the site of the recently demolished Les Beaucamps School building.
Rather than a handful of men working in close confines about 90m underground, at a site like Tower there are some of the largest earth movers in the UK digging a hole 180m on the surface.