Restraints influencing the choice of an alignement are increasing stronger and the road engineer may be led to cross a deposit of different waste materials from human origin. he may also find it after alignment has been chosen.

The engineer is faced with unusual difficulties when he must cross what geotechnicians describe willingly as "lower dustbib".

The quality of this article is to provide both a general framework of study of these particular deposite and a more detailed framework of technicla problems and questions related to inviromental protection.