The fill is not levelled, as such, but spread to make it level. A subtle distinction, I know. Presumably it is dumped by truck or some such first.

régaler - Etaler un matériau en couche uniforme sur une surface déterminé
[Dico-TP, by the same people as Dicobat]

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Note added at 4 hrs (2007-03-12 17:14:16 GMT)
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Also:
régalage - Action consistant à étaler un matériau déversé en vrac en une couche uniforme ou à répandre directement, en épaisseur régulière, un matériau de chaussée traité ou non.
Le matériau ainsi répandu sur une surface ou dans un encaissement est régalé au moyen d'un engin approprié (décapeuse ou bouteur).
[Dicobat]

The key words here are "déversé en vrac" : it has to be spread before it can be levelled. Levelling only applies to something that has been spread beforehand or is being spread simultaneously. It would also involve a "niveleuse" (grader) in preference to a scraper or bulldozer which will only approximate levelling.

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Note added at 4 hrs (2007-03-12 17:17:22 GMT)
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Sorry, an explanation of "turn it round" : it depends how you translate "remblai", which can be the fill used to make something, or the thing made with that fill, such as a road or an embankment. If you translate "remblai" as "embankment", say, then it is not spread (though it could be levelled, supposing it preexisted), and you would have to introduce the notion of the fill (of which the embankment is made) being spread (then levelled - though actually it is NOT levelled since it is convex - to allow water to run off, presumably).